1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/workgroup.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "interpreter/linkResolver.hpp"
41 #include "interpreter/oopMapCache.hpp"
42 #include "jvmtifiles/jvmtiEnv.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logConfiguration.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/handshake.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/prefetch.inline.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/safepointMechanism.inline.hpp"
82 #include "runtime/sharedRuntime.hpp"
83 #include "runtime/statSampler.hpp"
84 #include "runtime/stubRoutines.hpp"
85 #include "runtime/sweeper.hpp"
86 #include "runtime/task.hpp"
87 #include "runtime/thread.inline.hpp"
88 #include "runtime/threadCritical.hpp"
89 #include "runtime/threadSMR.inline.hpp"
90 #include "runtime/timer.hpp"
91 #include "runtime/timerTrace.hpp"
92 #include "runtime/vframe.hpp"
93 #include "runtime/vframeArray.hpp"
94 #include "runtime/vframe_hp.hpp"
95 #include "runtime/vmThread.hpp"
96 #include "runtime/vm_operations.hpp"
97 #include "runtime/vm_version.hpp"
98 #include "services/attachListener.hpp"
99 #include "services/management.hpp"
100 #include "services/memTracker.hpp"
101 #include "services/threadService.hpp"
102 #include "trace/traceMacros.hpp"
103 #include "trace/tracing.hpp"
104 #include "utilities/align.hpp"
105 #include "utilities/defaultStream.hpp"
106 #include "utilities/dtrace.hpp"
107 #include "utilities/events.hpp"
108 #include "utilities/macros.hpp"
109 #include "utilities/preserveException.hpp"
110 #include "utilities/resourceHash.hpp"
111 #include "utilities/vmError.hpp"
112 #if INCLUDE_ALL_GCS
113 #include "gc/cms/concurrentMarkSweepThread.hpp"
114 #include "gc/g1/concurrentMarkThread.inline.hpp"
115 #include "gc/parallel/pcTasks.hpp"
116 #endif // INCLUDE_ALL_GCS
117 #if INCLUDE_JVMCI
118 #include "jvmci/jvmciCompiler.hpp"
119 #include "jvmci/jvmciRuntime.hpp"
120 #include "logging/logHandle.hpp"
121 #endif
122 #ifdef COMPILER1
123 #include "c1/c1_Compiler.hpp"
124 #endif
125 #ifdef COMPILER2
126 #include "opto/c2compiler.hpp"
127 #include "opto/idealGraphPrinter.hpp"
128 #endif
129 #if INCLUDE_RTM_OPT
130 #include "runtime/rtmLocking.hpp"
131 #endif
132
133 // Initialization after module runtime initialization
134 void universe_post_module_init(); // must happen after call_initPhase2
135
136 #ifdef DTRACE_ENABLED
137
138 // Only bother with this argument setup if dtrace is available
139
140 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
141 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
142
143 #define DTRACE_THREAD_PROBE(probe, javathread) \
144 { \
145 ResourceMark rm(this); \
146 int len = 0; \
147 const char* name = (javathread)->get_thread_name(); \
148 len = strlen(name); \
149 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
150 (char *) name, len, \
151 java_lang_Thread::thread_id((javathread)->threadObj()), \
152 (uintptr_t) (javathread)->osthread()->thread_id(), \
153 java_lang_Thread::is_daemon((javathread)->threadObj())); \
154 }
155
156 #else // ndef DTRACE_ENABLED
157
158 #define DTRACE_THREAD_PROBE(probe, javathread)
159
160 #endif // ndef DTRACE_ENABLED
161
162 #ifndef USE_LIBRARY_BASED_TLS_ONLY
163 // Current thread is maintained as a thread-local variable
164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
165 #endif
166 // Class hierarchy
167 // - Thread
168 // - VMThread
169 // - WatcherThread
170 // - ConcurrentMarkSweepThread
171 // - JavaThread
172 // - CompilerThread
173
174 // ======= Thread ========
175 // Support for forcing alignment of thread objects for biased locking
176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
177 if (UseBiasedLocking) {
178 const int alignment = markOopDesc::biased_lock_alignment;
179 size_t aligned_size = size + (alignment - sizeof(intptr_t));
180 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
181 : AllocateHeap(aligned_size, flags, CURRENT_PC,
182 AllocFailStrategy::RETURN_NULL);
183 void* aligned_addr = align_up(real_malloc_addr, alignment);
184 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
185 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
186 "JavaThread alignment code overflowed allocated storage");
187 if (aligned_addr != real_malloc_addr) {
188 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
189 p2i(real_malloc_addr),
190 p2i(aligned_addr));
191 }
192 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
193 return aligned_addr;
194 } else {
195 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
196 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
197 }
198 }
199
200 void Thread::operator delete(void* p) {
201 if (UseBiasedLocking) {
202 FreeHeap(((Thread*) p)->_real_malloc_address);
203 } else {
204 FreeHeap(p);
205 }
206 }
207
208 void JavaThread::smr_delete() {
209 if (_on_thread_list) {
210 Threads::smr_delete(this);
211 } else {
212 delete this;
213 }
214 }
215
216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
217 // JavaThread
218
219
220 Thread::Thread() {
221 // stack and get_thread
222 set_stack_base(NULL);
223 set_stack_size(0);
224 set_self_raw_id(0);
225 set_lgrp_id(-1);
226 DEBUG_ONLY(clear_suspendible_thread();)
227
228 // allocated data structures
229 set_osthread(NULL);
230 set_resource_area(new (mtThread)ResourceArea());
231 DEBUG_ONLY(_current_resource_mark = NULL;)
232 set_handle_area(new (mtThread) HandleArea(NULL));
233 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
234 set_active_handles(NULL);
235 set_free_handle_block(NULL);
236 set_last_handle_mark(NULL);
237
238 // This initial value ==> never claimed.
239 _oops_do_parity = 0;
240 _threads_hazard_ptr = NULL;
241 _nested_threads_hazard_ptr = NULL;
242 _nested_threads_hazard_ptr_cnt = 0;
243
244 // the handle mark links itself to last_handle_mark
245 new HandleMark(this);
246
247 // plain initialization
248 debug_only(_owned_locks = NULL;)
249 debug_only(_allow_allocation_count = 0;)
250 NOT_PRODUCT(_allow_safepoint_count = 0;)
251 NOT_PRODUCT(_skip_gcalot = false;)
252 _jvmti_env_iteration_count = 0;
253 set_allocated_bytes(0);
254 _vm_operation_started_count = 0;
255 _vm_operation_completed_count = 0;
256 _current_pending_monitor = NULL;
257 _current_pending_monitor_is_from_java = true;
258 _current_waiting_monitor = NULL;
259 _num_nested_signal = 0;
260 omFreeList = NULL;
261 omFreeCount = 0;
262 omFreeProvision = 32;
263 omInUseList = NULL;
264 omInUseCount = 0;
265
266 #ifdef ASSERT
267 _visited_for_critical_count = false;
268 #endif
269
270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
271 Monitor::_safepoint_check_sometimes);
272 _suspend_flags = 0;
273
274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
275 _hashStateX = os::random();
276 _hashStateY = 842502087;
277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
278 _hashStateW = 273326509;
279
280 _OnTrap = 0;
281 _schedctl = NULL;
282 _Stalled = 0;
283 _TypeTag = 0x2BAD;
284
285 // Many of the following fields are effectively final - immutable
286 // Note that nascent threads can't use the Native Monitor-Mutex
287 // construct until the _MutexEvent is initialized ...
288 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
289 // we might instead use a stack of ParkEvents that we could provision on-demand.
290 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
291 // and ::Release()
292 _ParkEvent = ParkEvent::Allocate(this);
293 _SleepEvent = ParkEvent::Allocate(this);
294 _MutexEvent = ParkEvent::Allocate(this);
295 _MuxEvent = ParkEvent::Allocate(this);
296
297 #ifdef CHECK_UNHANDLED_OOPS
298 if (CheckUnhandledOops) {
299 _unhandled_oops = new UnhandledOops(this);
300 }
301 #endif // CHECK_UNHANDLED_OOPS
302 #ifdef ASSERT
303 if (UseBiasedLocking) {
304 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
307 "bug in forced alignment of thread objects");
308 }
309 #endif // ASSERT
310 }
311
312 void Thread::initialize_thread_current() {
313 #ifndef USE_LIBRARY_BASED_TLS_ONLY
314 assert(_thr_current == NULL, "Thread::current already initialized");
315 _thr_current = this;
316 #endif
317 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
318 ThreadLocalStorage::set_thread(this);
319 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
320 }
321
322 void Thread::clear_thread_current() {
323 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
325 _thr_current = NULL;
326 #endif
327 ThreadLocalStorage::set_thread(NULL);
328 }
329
330 void Thread::record_stack_base_and_size() {
331 set_stack_base(os::current_stack_base());
332 set_stack_size(os::current_stack_size());
333 // CR 7190089: on Solaris, primordial thread's stack is adjusted
334 // in initialize_thread(). Without the adjustment, stack size is
335 // incorrect if stack is set to unlimited (ulimit -s unlimited).
336 // So far, only Solaris has real implementation of initialize_thread().
337 //
338 // set up any platform-specific state.
339 os::initialize_thread(this);
340
341 // Set stack limits after thread is initialized.
342 if (is_Java_thread()) {
343 ((JavaThread*) this)->set_stack_overflow_limit();
344 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
345 }
346 #if INCLUDE_NMT
347 // record thread's native stack, stack grows downward
348 MemTracker::record_thread_stack(stack_end(), stack_size());
349 #endif // INCLUDE_NMT
350 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
351 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
352 os::current_thread_id(), p2i(stack_base() - stack_size()),
353 p2i(stack_base()), stack_size()/1024);
354 }
355
356
357 Thread::~Thread() {
358 EVENT_THREAD_DESTRUCT(this);
359
360 // stack_base can be NULL if the thread is never started or exited before
361 // record_stack_base_and_size called. Although, we would like to ensure
362 // that all started threads do call record_stack_base_and_size(), there is
363 // not proper way to enforce that.
364 #if INCLUDE_NMT
365 if (_stack_base != NULL) {
366 MemTracker::release_thread_stack(stack_end(), stack_size());
367 #ifdef ASSERT
368 set_stack_base(NULL);
369 #endif
370 }
371 #endif // INCLUDE_NMT
372
373 // deallocate data structures
374 delete resource_area();
375 // since the handle marks are using the handle area, we have to deallocated the root
376 // handle mark before deallocating the thread's handle area,
377 assert(last_handle_mark() != NULL, "check we have an element");
378 delete last_handle_mark();
379 assert(last_handle_mark() == NULL, "check we have reached the end");
380
381 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
382 // We NULL out the fields for good hygiene.
383 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
384 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
385 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
386 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
387
388 delete handle_area();
389 delete metadata_handles();
390
391 // SR_handler uses this as a termination indicator -
392 // needs to happen before os::free_thread()
393 delete _SR_lock;
394 _SR_lock = NULL;
395
396 // osthread() can be NULL, if creation of thread failed.
397 if (osthread() != NULL) os::free_thread(osthread());
398
399 // clear Thread::current if thread is deleting itself.
400 // Needed to ensure JNI correctly detects non-attached threads.
401 if (this == Thread::current()) {
402 clear_thread_current();
403 }
404
405 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
406 }
407
408 // NOTE: dummy function for assertion purpose.
409 void Thread::run() {
410 ShouldNotReachHere();
411 }
412
413 #ifdef ASSERT
414 // A JavaThread is considered "dangling" if it is not the current
415 // thread, has been added the Threads list, the system is not at a
416 // safepoint and the Thread is not "protected".
417 //
418 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
419 assert(!thread->is_Java_thread() || Thread::current() == thread ||
420 !((JavaThread *) thread)->on_thread_list() ||
421 SafepointSynchronize::is_at_safepoint() ||
422 Threads::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
423 "possibility of dangling Thread pointer");
424 }
425 #endif
426
427 ThreadPriority Thread::get_priority(const Thread* const thread) {
428 ThreadPriority priority;
429 // Can return an error!
430 (void)os::get_priority(thread, priority);
431 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
432 return priority;
433 }
434
435 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
436 debug_only(check_for_dangling_thread_pointer(thread);)
437 // Can return an error!
438 (void)os::set_priority(thread, priority);
439 }
440
441
442 void Thread::start(Thread* thread) {
443 // Start is different from resume in that its safety is guaranteed by context or
444 // being called from a Java method synchronized on the Thread object.
445 if (!DisableStartThread) {
446 if (thread->is_Java_thread()) {
447 // Initialize the thread state to RUNNABLE before starting this thread.
448 // Can not set it after the thread started because we do not know the
449 // exact thread state at that time. It could be in MONITOR_WAIT or
450 // in SLEEPING or some other state.
451 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
452 java_lang_Thread::RUNNABLE);
453 }
454 os::start_thread(thread);
455 }
456 }
457
458 // Enqueue a VM_Operation to do the job for us - sometime later
459 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
460 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
461 VMThread::execute(vm_stop);
462 }
463
464
465 // Check if an external suspend request has completed (or has been
466 // cancelled). Returns true if the thread is externally suspended and
467 // false otherwise.
468 //
469 // The bits parameter returns information about the code path through
470 // the routine. Useful for debugging:
471 //
472 // set in is_ext_suspend_completed():
473 // 0x00000001 - routine was entered
474 // 0x00000010 - routine return false at end
475 // 0x00000100 - thread exited (return false)
476 // 0x00000200 - suspend request cancelled (return false)
477 // 0x00000400 - thread suspended (return true)
478 // 0x00001000 - thread is in a suspend equivalent state (return true)
479 // 0x00002000 - thread is native and walkable (return true)
480 // 0x00004000 - thread is native_trans and walkable (needed retry)
481 //
482 // set in wait_for_ext_suspend_completion():
483 // 0x00010000 - routine was entered
484 // 0x00020000 - suspend request cancelled before loop (return false)
485 // 0x00040000 - thread suspended before loop (return true)
486 // 0x00080000 - suspend request cancelled in loop (return false)
487 // 0x00100000 - thread suspended in loop (return true)
488 // 0x00200000 - suspend not completed during retry loop (return false)
489
490 // Helper class for tracing suspend wait debug bits.
491 //
492 // 0x00000100 indicates that the target thread exited before it could
493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
494 // 0x00080000 each indicate a cancelled suspend request so they don't
495 // count as wait failures either.
496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
497
498 class TraceSuspendDebugBits : public StackObj {
499 private:
500 JavaThread * jt;
501 bool is_wait;
502 bool called_by_wait; // meaningful when !is_wait
503 uint32_t * bits;
504
505 public:
506 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
507 uint32_t *_bits) {
508 jt = _jt;
509 is_wait = _is_wait;
510 called_by_wait = _called_by_wait;
511 bits = _bits;
512 }
513
514 ~TraceSuspendDebugBits() {
515 if (!is_wait) {
516 #if 1
517 // By default, don't trace bits for is_ext_suspend_completed() calls.
518 // That trace is very chatty.
519 return;
520 #else
521 if (!called_by_wait) {
522 // If tracing for is_ext_suspend_completed() is enabled, then only
523 // trace calls to it from wait_for_ext_suspend_completion()
524 return;
525 }
526 #endif
527 }
528
529 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
530 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
531 MutexLocker ml(Threads_lock); // needed for get_thread_name()
532 ResourceMark rm;
533
534 tty->print_cr(
535 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
536 jt->get_thread_name(), *bits);
537
538 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
539 }
540 }
541 }
542 };
543 #undef DEBUG_FALSE_BITS
544
545
546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
547 uint32_t *bits) {
548 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
549
550 bool did_trans_retry = false; // only do thread_in_native_trans retry once
551 bool do_trans_retry; // flag to force the retry
552
553 *bits |= 0x00000001;
554
555 do {
556 do_trans_retry = false;
557
558 if (is_exiting()) {
559 // Thread is in the process of exiting. This is always checked
560 // first to reduce the risk of dereferencing a freed JavaThread.
561 *bits |= 0x00000100;
562 return false;
563 }
564
565 if (!is_external_suspend()) {
566 // Suspend request is cancelled. This is always checked before
567 // is_ext_suspended() to reduce the risk of a rogue resume
568 // confusing the thread that made the suspend request.
569 *bits |= 0x00000200;
570 return false;
571 }
572
573 if (is_ext_suspended()) {
574 // thread is suspended
575 *bits |= 0x00000400;
576 return true;
577 }
578
579 // Now that we no longer do hard suspends of threads running
580 // native code, the target thread can be changing thread state
581 // while we are in this routine:
582 //
583 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
584 //
585 // We save a copy of the thread state as observed at this moment
586 // and make our decision about suspend completeness based on the
587 // copy. This closes the race where the thread state is seen as
588 // _thread_in_native_trans in the if-thread_blocked check, but is
589 // seen as _thread_blocked in if-thread_in_native_trans check.
590 JavaThreadState save_state = thread_state();
591
592 if (save_state == _thread_blocked && is_suspend_equivalent()) {
593 // If the thread's state is _thread_blocked and this blocking
594 // condition is known to be equivalent to a suspend, then we can
595 // consider the thread to be externally suspended. This means that
596 // the code that sets _thread_blocked has been modified to do
597 // self-suspension if the blocking condition releases. We also
598 // used to check for CONDVAR_WAIT here, but that is now covered by
599 // the _thread_blocked with self-suspension check.
600 //
601 // Return true since we wouldn't be here unless there was still an
602 // external suspend request.
603 *bits |= 0x00001000;
604 return true;
605 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
606 // Threads running native code will self-suspend on native==>VM/Java
607 // transitions. If its stack is walkable (should always be the case
608 // unless this function is called before the actual java_suspend()
609 // call), then the wait is done.
610 *bits |= 0x00002000;
611 return true;
612 } else if (!called_by_wait && !did_trans_retry &&
613 save_state == _thread_in_native_trans &&
614 frame_anchor()->walkable()) {
615 // The thread is transitioning from thread_in_native to another
616 // thread state. check_safepoint_and_suspend_for_native_trans()
617 // will force the thread to self-suspend. If it hasn't gotten
618 // there yet we may have caught the thread in-between the native
619 // code check above and the self-suspend. Lucky us. If we were
620 // called by wait_for_ext_suspend_completion(), then it
621 // will be doing the retries so we don't have to.
622 //
623 // Since we use the saved thread state in the if-statement above,
624 // there is a chance that the thread has already transitioned to
625 // _thread_blocked by the time we get here. In that case, we will
626 // make a single unnecessary pass through the logic below. This
627 // doesn't hurt anything since we still do the trans retry.
628
629 *bits |= 0x00004000;
630
631 // Once the thread leaves thread_in_native_trans for another
632 // thread state, we break out of this retry loop. We shouldn't
633 // need this flag to prevent us from getting back here, but
634 // sometimes paranoia is good.
635 did_trans_retry = true;
636
637 // We wait for the thread to transition to a more usable state.
638 for (int i = 1; i <= SuspendRetryCount; i++) {
639 // We used to do an "os::yield_all(i)" call here with the intention
640 // that yielding would increase on each retry. However, the parameter
641 // is ignored on Linux which means the yield didn't scale up. Waiting
642 // on the SR_lock below provides a much more predictable scale up for
643 // the delay. It also provides a simple/direct point to check for any
644 // safepoint requests from the VMThread
645
646 // temporarily drops SR_lock while doing wait with safepoint check
647 // (if we're a JavaThread - the WatcherThread can also call this)
648 // and increase delay with each retry
649 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
650
651 // check the actual thread state instead of what we saved above
652 if (thread_state() != _thread_in_native_trans) {
653 // the thread has transitioned to another thread state so
654 // try all the checks (except this one) one more time.
655 do_trans_retry = true;
656 break;
657 }
658 } // end retry loop
659
660
661 }
662 } while (do_trans_retry);
663
664 *bits |= 0x00000010;
665 return false;
666 }
667
668 // Wait for an external suspend request to complete (or be cancelled).
669 // Returns true if the thread is externally suspended and false otherwise.
670 //
671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
672 uint32_t *bits) {
673 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
674 false /* !called_by_wait */, bits);
675
676 // local flag copies to minimize SR_lock hold time
677 bool is_suspended;
678 bool pending;
679 uint32_t reset_bits;
680
681 // set a marker so is_ext_suspend_completed() knows we are the caller
682 *bits |= 0x00010000;
683
684 // We use reset_bits to reinitialize the bits value at the top of
685 // each retry loop. This allows the caller to make use of any
686 // unused bits for their own marking purposes.
687 reset_bits = *bits;
688
689 {
690 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
691 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
692 delay, bits);
693 pending = is_external_suspend();
694 }
695 // must release SR_lock to allow suspension to complete
696
697 if (!pending) {
698 // A cancelled suspend request is the only false return from
699 // is_ext_suspend_completed() that keeps us from entering the
700 // retry loop.
701 *bits |= 0x00020000;
702 return false;
703 }
704
705 if (is_suspended) {
706 *bits |= 0x00040000;
707 return true;
708 }
709
710 for (int i = 1; i <= retries; i++) {
711 *bits = reset_bits; // reinit to only track last retry
712
713 // We used to do an "os::yield_all(i)" call here with the intention
714 // that yielding would increase on each retry. However, the parameter
715 // is ignored on Linux which means the yield didn't scale up. Waiting
716 // on the SR_lock below provides a much more predictable scale up for
717 // the delay. It also provides a simple/direct point to check for any
718 // safepoint requests from the VMThread
719
720 {
721 MutexLocker ml(SR_lock());
722 // wait with safepoint check (if we're a JavaThread - the WatcherThread
723 // can also call this) and increase delay with each retry
724 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
725
726 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
727 delay, bits);
728
729 // It is possible for the external suspend request to be cancelled
730 // (by a resume) before the actual suspend operation is completed.
731 // Refresh our local copy to see if we still need to wait.
732 pending = is_external_suspend();
733 }
734
735 if (!pending) {
736 // A cancelled suspend request is the only false return from
737 // is_ext_suspend_completed() that keeps us from staying in the
738 // retry loop.
739 *bits |= 0x00080000;
740 return false;
741 }
742
743 if (is_suspended) {
744 *bits |= 0x00100000;
745 return true;
746 }
747 } // end retry loop
748
749 // thread did not suspend after all our retries
750 *bits |= 0x00200000;
751 return false;
752 }
753
754 // Called from API entry points which perform stack walking. If the
755 // associated JavaThread is the current thread, then wait_for_suspend
756 // is not used. Otherwise, it determines if we should wait for the
757 // "other" thread to complete external suspension. (NOTE: in future
758 // releases the suspension mechanism should be reimplemented so this
759 // is not necessary.)
760 //
761 bool
762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
763 if (this != JavaThread::current()) {
764 // "other" threads require special handling.
765 if (wait_for_suspend) {
766 // We are allowed to wait for the external suspend to complete
767 // so give the other thread a chance to get suspended.
768 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
769 SuspendRetryDelay, bits)) {
770 // Didn't make it so let the caller know.
771 return false;
772 }
773 }
774 // We aren't allowed to wait for the external suspend to complete
775 // so if the other thread isn't externally suspended we need to
776 // let the caller know.
777 else if (!is_ext_suspend_completed_with_lock(bits)) {
778 return false;
779 }
780 }
781
782 return true;
783 }
784
785 #ifndef PRODUCT
786 void JavaThread::record_jump(address target, address instr, const char* file,
787 int line) {
788
789 // This should not need to be atomic as the only way for simultaneous
790 // updates is via interrupts. Even then this should be rare or non-existent
791 // and we don't care that much anyway.
792
793 int index = _jmp_ring_index;
794 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
795 _jmp_ring[index]._target = (intptr_t) target;
796 _jmp_ring[index]._instruction = (intptr_t) instr;
797 _jmp_ring[index]._file = file;
798 _jmp_ring[index]._line = line;
799 }
800 #endif // PRODUCT
801
802 void Thread::interrupt(Thread* thread) {
803 debug_only(check_for_dangling_thread_pointer(thread);)
804 os::interrupt(thread);
805 }
806
807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
808 debug_only(check_for_dangling_thread_pointer(thread);)
809 // Note: If clear_interrupted==false, this simply fetches and
810 // returns the value of the field osthread()->interrupted().
811 return os::is_interrupted(thread, clear_interrupted);
812 }
813
814
815 // GC Support
816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
817 int thread_parity = _oops_do_parity;
818 if (thread_parity != strong_roots_parity) {
819 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
820 if (res == thread_parity) {
821 return true;
822 } else {
823 guarantee(res == strong_roots_parity, "Or else what?");
824 return false;
825 }
826 }
827 return false;
828 }
829
830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
831 active_handles()->oops_do(f);
832 // Do oop for ThreadShadow
833 f->do_oop((oop*)&_pending_exception);
834 handle_area()->oops_do(f);
835
836 if (MonitorInUseLists) {
837 // When using thread local monitor lists, we scan them here,
838 // and the remaining global monitors in ObjectSynchronizer::oops_do().
839 ObjectSynchronizer::thread_local_used_oops_do(this, f);
840 }
841 }
842
843 void Thread::metadata_handles_do(void f(Metadata*)) {
844 // Only walk the Handles in Thread.
845 if (metadata_handles() != NULL) {
846 for (int i = 0; i< metadata_handles()->length(); i++) {
847 f(metadata_handles()->at(i));
848 }
849 }
850 }
851
852 void Thread::print_on(outputStream* st) const {
853 // get_priority assumes osthread initialized
854 if (osthread() != NULL) {
855 int os_prio;
856 if (os::get_native_priority(this, &os_prio) == OS_OK) {
857 st->print("os_prio=%d ", os_prio);
858 }
859 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
860 ext().print_on(st);
861 osthread()->print_on(st);
862 }
863 if (_threads_hazard_ptr != NULL) {
864 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
865 }
866 if (_nested_threads_hazard_ptr != NULL) {
867 print_nested_threads_hazard_ptrs_on(st);
868 }
869 st->print(" ");
870 debug_only(if (WizardMode) print_owned_locks_on(st);)
871 }
872
873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
874 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
875
876 if (EnableThreadSMRStatistics) {
877 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
878 }
879 st->print(", _nested_threads_hazard_ptrs=");
880 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
881 node = node->next()) {
882 if (node != _nested_threads_hazard_ptr) {
883 // First node does not need a comma-space separator.
884 st->print(", ");
885 }
886 st->print(INTPTR_FORMAT, p2i(node->t_list()));
887 }
888 }
889
890 // Thread::print_on_error() is called by fatal error handler. Don't use
891 // any lock or allocate memory.
892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
893 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
894
895 if (is_VM_thread()) { st->print("VMThread"); }
896 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
897 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
898 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
899 else { st->print("Thread"); }
900
901 if (is_Named_thread()) {
902 st->print(" \"%s\"", name());
903 }
904
905 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
906 p2i(stack_end()), p2i(stack_base()));
907
908 if (osthread()) {
909 st->print(" [id=%d]", osthread()->thread_id());
910 }
911
912 if (_threads_hazard_ptr != NULL) {
913 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
914 }
915 if (_nested_threads_hazard_ptr != NULL) {
916 print_nested_threads_hazard_ptrs_on(st);
917 }
918 }
919
920 void Thread::print_value_on(outputStream* st) const {
921 if (is_Named_thread()) {
922 st->print(" \"%s\" ", name());
923 }
924 st->print(INTPTR_FORMAT, p2i(this)); // print address
925 }
926
927 #ifdef ASSERT
928 void Thread::print_owned_locks_on(outputStream* st) const {
929 Monitor *cur = _owned_locks;
930 if (cur == NULL) {
931 st->print(" (no locks) ");
932 } else {
933 st->print_cr(" Locks owned:");
934 while (cur) {
935 cur->print_on(st);
936 cur = cur->next();
937 }
938 }
939 }
940
941 static int ref_use_count = 0;
942
943 bool Thread::owns_locks_but_compiled_lock() const {
944 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
945 if (cur != Compile_lock) return true;
946 }
947 return false;
948 }
949
950
951 #endif
952
953 #ifndef PRODUCT
954
955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
957 // no threads which allow_vm_block's are held
958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
959 // Check if current thread is allowed to block at a safepoint
960 if (!(_allow_safepoint_count == 0)) {
961 fatal("Possible safepoint reached by thread that does not allow it");
962 }
963 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
964 fatal("LEAF method calling lock?");
965 }
966
967 #ifdef ASSERT
968 if (potential_vm_operation && is_Java_thread()
969 && !Universe::is_bootstrapping()) {
970 // Make sure we do not hold any locks that the VM thread also uses.
971 // This could potentially lead to deadlocks
972 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
973 // Threads_lock is special, since the safepoint synchronization will not start before this is
974 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
975 // since it is used to transfer control between JavaThreads and the VMThread
976 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
977 if ((cur->allow_vm_block() &&
978 cur != Threads_lock &&
979 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
980 cur != VMOperationRequest_lock &&
981 cur != VMOperationQueue_lock) ||
982 cur->rank() == Mutex::special) {
983 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
984 }
985 }
986 }
987
988 if (GCALotAtAllSafepoints) {
989 // We could enter a safepoint here and thus have a gc
990 InterfaceSupport::check_gc_alot();
991 }
992 #endif
993 }
994 #endif
995
996 bool Thread::is_in_stack(address adr) const {
997 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
998 address end = os::current_stack_pointer();
999 // Allow non Java threads to call this without stack_base
1000 if (_stack_base == NULL) return true;
1001 if (stack_base() >= adr && adr >= end) return true;
1002
1003 return false;
1004 }
1005
1006 bool Thread::is_in_usable_stack(address adr) const {
1007 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1008 size_t usable_stack_size = _stack_size - stack_guard_size;
1009
1010 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1011 }
1012
1013
1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1016 // used for compilation in the future. If that change is made, the need for these methods
1017 // should be revisited, and they should be removed if possible.
1018
1019 bool Thread::is_lock_owned(address adr) const {
1020 return on_local_stack(adr);
1021 }
1022
1023 bool Thread::set_as_starting_thread() {
1024 // NOTE: this must be called inside the main thread.
1025 return os::create_main_thread((JavaThread*)this);
1026 }
1027
1028 static void initialize_class(Symbol* class_name, TRAPS) {
1029 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1030 InstanceKlass::cast(klass)->initialize(CHECK);
1031 }
1032
1033
1034 // Creates the initial ThreadGroup
1035 static Handle create_initial_thread_group(TRAPS) {
1036 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1037 InstanceKlass* ik = InstanceKlass::cast(k);
1038
1039 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1040 {
1041 JavaValue result(T_VOID);
1042 JavaCalls::call_special(&result,
1043 system_instance,
1044 ik,
1045 vmSymbols::object_initializer_name(),
1046 vmSymbols::void_method_signature(),
1047 CHECK_NH);
1048 }
1049 Universe::set_system_thread_group(system_instance());
1050
1051 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1052 {
1053 JavaValue result(T_VOID);
1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055 JavaCalls::call_special(&result,
1056 main_instance,
1057 ik,
1058 vmSymbols::object_initializer_name(),
1059 vmSymbols::threadgroup_string_void_signature(),
1060 system_instance,
1061 string,
1062 CHECK_NH);
1063 }
1064 return main_instance;
1065 }
1066
1067 // Creates the initial Thread
1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1069 TRAPS) {
1070 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1071 InstanceKlass* ik = InstanceKlass::cast(k);
1072 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1073
1074 java_lang_Thread::set_thread(thread_oop(), thread);
1075 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076 thread->set_threadObj(thread_oop());
1077
1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079
1080 JavaValue result(T_VOID);
1081 JavaCalls::call_special(&result, thread_oop,
1082 ik,
1083 vmSymbols::object_initializer_name(),
1084 vmSymbols::threadgroup_string_void_signature(),
1085 thread_group,
1086 string,
1087 CHECK_NULL);
1088 return thread_oop();
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098 fieldDescriptor fd;
1099 bool found = k != NULL &&
1100 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101 vmSymbols::string_signature(), &fd);
1102 if (found) {
1103 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104 if (name_oop == NULL) {
1105 return NULL;
1106 }
1107 const char* name = java_lang_String::as_utf8_string(name_oop,
1108 java_runtime_name,
1109 sizeof(java_runtime_name));
1110 return name;
1111 } else {
1112 return NULL;
1113 }
1114 }
1115
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120 fieldDescriptor fd;
1121 bool found = k != NULL &&
1122 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123 vmSymbols::string_signature(), &fd);
1124 if (found) {
1125 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126 if (name_oop == NULL) {
1127 return NULL;
1128 }
1129 const char* name = java_lang_String::as_utf8_string(name_oop,
1130 java_runtime_version,
1131 sizeof(java_runtime_version));
1132 return name;
1133 } else {
1134 return NULL;
1135 }
1136 }
1137
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142 if (klass != NULL) {
1143 JavaValue result(T_VOID);
1144 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145 vmSymbols::void_method_signature(),
1146 CHECK);
1147 }
1148 }
1149
1150 static void reset_vm_info_property(TRAPS) {
1151 // the vm info string
1152 ResourceMark rm(THREAD);
1153 const char *vm_info = VM_Version::vm_info_string();
1154
1155 // java.lang.System class
1156 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1157
1158 // setProperty arguments
1159 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1160 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1161
1162 // return value
1163 JavaValue r(T_OBJECT);
1164
1165 // public static String setProperty(String key, String value);
1166 JavaCalls::call_static(&r,
1167 klass,
1168 vmSymbols::setProperty_name(),
1169 vmSymbols::string_string_string_signature(),
1170 key_str,
1171 value_str,
1172 CHECK);
1173 }
1174
1175
1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1177 bool daemon, TRAPS) {
1178 assert(thread_group.not_null(), "thread group should be specified");
1179 assert(threadObj() == NULL, "should only create Java thread object once");
1180
1181 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1182 InstanceKlass* ik = InstanceKlass::cast(k);
1183 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1184
1185 java_lang_Thread::set_thread(thread_oop(), this);
1186 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1187 set_threadObj(thread_oop());
1188
1189 JavaValue result(T_VOID);
1190 if (thread_name != NULL) {
1191 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1192 // Thread gets assigned specified name and null target
1193 JavaCalls::call_special(&result,
1194 thread_oop,
1195 ik,
1196 vmSymbols::object_initializer_name(),
1197 vmSymbols::threadgroup_string_void_signature(),
1198 thread_group, // Argument 1
1199 name, // Argument 2
1200 THREAD);
1201 } else {
1202 // Thread gets assigned name "Thread-nnn" and null target
1203 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1204 JavaCalls::call_special(&result,
1205 thread_oop,
1206 ik,
1207 vmSymbols::object_initializer_name(),
1208 vmSymbols::threadgroup_runnable_void_signature(),
1209 thread_group, // Argument 1
1210 Handle(), // Argument 2
1211 THREAD);
1212 }
1213
1214
1215 if (daemon) {
1216 java_lang_Thread::set_daemon(thread_oop());
1217 }
1218
1219 if (HAS_PENDING_EXCEPTION) {
1220 return;
1221 }
1222
1223 Klass* group = SystemDictionary::ThreadGroup_klass();
1224 Handle threadObj(THREAD, this->threadObj());
1225
1226 JavaCalls::call_special(&result,
1227 thread_group,
1228 group,
1229 vmSymbols::add_method_name(),
1230 vmSymbols::thread_void_signature(),
1231 threadObj, // Arg 1
1232 THREAD);
1233 }
1234
1235 // NamedThread -- non-JavaThread subclasses with multiple
1236 // uniquely named instances should derive from this.
1237 NamedThread::NamedThread() : Thread() {
1238 _name = NULL;
1239 _processed_thread = NULL;
1240 _gc_id = GCId::undefined();
1241 }
1242
1243 NamedThread::~NamedThread() {
1244 if (_name != NULL) {
1245 FREE_C_HEAP_ARRAY(char, _name);
1246 _name = NULL;
1247 }
1248 }
1249
1250 void NamedThread::set_name(const char* format, ...) {
1251 guarantee(_name == NULL, "Only get to set name once.");
1252 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1253 guarantee(_name != NULL, "alloc failure");
1254 va_list ap;
1255 va_start(ap, format);
1256 jio_vsnprintf(_name, max_name_len, format, ap);
1257 va_end(ap);
1258 }
1259
1260 void NamedThread::initialize_named_thread() {
1261 set_native_thread_name(name());
1262 }
1263
1264 void NamedThread::print_on(outputStream* st) const {
1265 st->print("\"%s\" ", name());
1266 Thread::print_on(st);
1267 st->cr();
1268 }
1269
1270
1271 // ======= WatcherThread ========
1272
1273 // The watcher thread exists to simulate timer interrupts. It should
1274 // be replaced by an abstraction over whatever native support for
1275 // timer interrupts exists on the platform.
1276
1277 WatcherThread* WatcherThread::_watcher_thread = NULL;
1278 bool WatcherThread::_startable = false;
1279 volatile bool WatcherThread::_should_terminate = false;
1280
1281 WatcherThread::WatcherThread() : Thread() {
1282 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1283 if (os::create_thread(this, os::watcher_thread)) {
1284 _watcher_thread = this;
1285
1286 // Set the watcher thread to the highest OS priority which should not be
1287 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1288 // is created. The only normal thread using this priority is the reference
1289 // handler thread, which runs for very short intervals only.
1290 // If the VMThread's priority is not lower than the WatcherThread profiling
1291 // will be inaccurate.
1292 os::set_priority(this, MaxPriority);
1293 if (!DisableStartThread) {
1294 os::start_thread(this);
1295 }
1296 }
1297 }
1298
1299 int WatcherThread::sleep() const {
1300 // The WatcherThread does not participate in the safepoint protocol
1301 // for the PeriodicTask_lock because it is not a JavaThread.
1302 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1303
1304 if (_should_terminate) {
1305 // check for termination before we do any housekeeping or wait
1306 return 0; // we did not sleep.
1307 }
1308
1309 // remaining will be zero if there are no tasks,
1310 // causing the WatcherThread to sleep until a task is
1311 // enrolled
1312 int remaining = PeriodicTask::time_to_wait();
1313 int time_slept = 0;
1314
1315 // we expect this to timeout - we only ever get unparked when
1316 // we should terminate or when a new task has been enrolled
1317 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1318
1319 jlong time_before_loop = os::javaTimeNanos();
1320
1321 while (true) {
1322 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1323 remaining);
1324 jlong now = os::javaTimeNanos();
1325
1326 if (remaining == 0) {
1327 // if we didn't have any tasks we could have waited for a long time
1328 // consider the time_slept zero and reset time_before_loop
1329 time_slept = 0;
1330 time_before_loop = now;
1331 } else {
1332 // need to recalculate since we might have new tasks in _tasks
1333 time_slept = (int) ((now - time_before_loop) / 1000000);
1334 }
1335
1336 // Change to task list or spurious wakeup of some kind
1337 if (timedout || _should_terminate) {
1338 break;
1339 }
1340
1341 remaining = PeriodicTask::time_to_wait();
1342 if (remaining == 0) {
1343 // Last task was just disenrolled so loop around and wait until
1344 // another task gets enrolled
1345 continue;
1346 }
1347
1348 remaining -= time_slept;
1349 if (remaining <= 0) {
1350 break;
1351 }
1352 }
1353
1354 return time_slept;
1355 }
1356
1357 void WatcherThread::run() {
1358 assert(this == watcher_thread(), "just checking");
1359
1360 this->record_stack_base_and_size();
1361 this->set_native_thread_name(this->name());
1362 this->set_active_handles(JNIHandleBlock::allocate_block());
1363 while (true) {
1364 assert(watcher_thread() == Thread::current(), "thread consistency check");
1365 assert(watcher_thread() == this, "thread consistency check");
1366
1367 // Calculate how long it'll be until the next PeriodicTask work
1368 // should be done, and sleep that amount of time.
1369 int time_waited = sleep();
1370
1371 if (VMError::is_error_reported()) {
1372 // A fatal error has happened, the error handler(VMError::report_and_die)
1373 // should abort JVM after creating an error log file. However in some
1374 // rare cases, the error handler itself might deadlock. Here periodically
1375 // check for error reporting timeouts, and if it happens, just proceed to
1376 // abort the VM.
1377
1378 // This code is in WatcherThread because WatcherThread wakes up
1379 // periodically so the fatal error handler doesn't need to do anything;
1380 // also because the WatcherThread is less likely to crash than other
1381 // threads.
1382
1383 for (;;) {
1384 // Note: we use naked sleep in this loop because we want to avoid using
1385 // any kind of VM infrastructure which may be broken at this point.
1386 if (VMError::check_timeout()) {
1387 // We hit error reporting timeout. Error reporting was interrupted and
1388 // will be wrapping things up now (closing files etc). Give it some more
1389 // time, then quit the VM.
1390 os::naked_short_sleep(200);
1391 // Print a message to stderr.
1392 fdStream err(defaultStream::output_fd());
1393 err.print_raw_cr("# [ timer expired, abort... ]");
1394 // skip atexit/vm_exit/vm_abort hooks
1395 os::die();
1396 }
1397
1398 // Wait a second, then recheck for timeout.
1399 os::naked_short_sleep(999);
1400 }
1401 }
1402
1403 if (_should_terminate) {
1404 // check for termination before posting the next tick
1405 break;
1406 }
1407
1408 PeriodicTask::real_time_tick(time_waited);
1409 }
1410
1411 // Signal that it is terminated
1412 {
1413 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1414 _watcher_thread = NULL;
1415 Terminator_lock->notify();
1416 }
1417 }
1418
1419 void WatcherThread::start() {
1420 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1421
1422 if (watcher_thread() == NULL && _startable) {
1423 _should_terminate = false;
1424 // Create the single instance of WatcherThread
1425 new WatcherThread();
1426 }
1427 }
1428
1429 void WatcherThread::make_startable() {
1430 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1431 _startable = true;
1432 }
1433
1434 void WatcherThread::stop() {
1435 {
1436 // Follow normal safepoint aware lock enter protocol since the
1437 // WatcherThread is stopped by another JavaThread.
1438 MutexLocker ml(PeriodicTask_lock);
1439 _should_terminate = true;
1440
1441 WatcherThread* watcher = watcher_thread();
1442 if (watcher != NULL) {
1443 // unpark the WatcherThread so it can see that it should terminate
1444 watcher->unpark();
1445 }
1446 }
1447
1448 MutexLocker mu(Terminator_lock);
1449
1450 while (watcher_thread() != NULL) {
1451 // This wait should make safepoint checks, wait without a timeout,
1452 // and wait as a suspend-equivalent condition.
1453 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1454 Mutex::_as_suspend_equivalent_flag);
1455 }
1456 }
1457
1458 void WatcherThread::unpark() {
1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460 PeriodicTask_lock->notify();
1461 }
1462
1463 void WatcherThread::print_on(outputStream* st) const {
1464 st->print("\"%s\" ", name());
1465 Thread::print_on(st);
1466 st->cr();
1467 }
1468
1469 // ======= JavaThread ========
1470
1471 #if INCLUDE_JVMCI
1472
1473 jlong* JavaThread::_jvmci_old_thread_counters;
1474
1475 bool jvmci_counters_include(JavaThread* thread) {
1476 oop threadObj = thread->threadObj();
1477 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481 if (JVMCICounterSize > 0) {
1482 MutexLocker tl(Threads_lock);
1483 JavaThreadIteratorWithHandle jtiwh;
1484 for (int i = 0; i < array->length(); i++) {
1485 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1486 }
1487 for (; JavaThread *tp = jtiwh.next(); ) {
1488 if (jvmci_counters_include(tp)) {
1489 for (int i = 0; i < array->length(); i++) {
1490 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1491 }
1492 }
1493 }
1494 }
1495 }
1496
1497 #endif // INCLUDE_JVMCI
1498
1499 // A JavaThread is a normal Java thread
1500
1501 void JavaThread::initialize() {
1502 // Initialize fields
1503
1504 set_saved_exception_pc(NULL);
1505 set_threadObj(NULL);
1506 _anchor.clear();
1507 set_entry_point(NULL);
1508 set_jni_functions(jni_functions());
1509 set_callee_target(NULL);
1510 set_vm_result(NULL);
1511 set_vm_result_2(NULL);
1512 set_vframe_array_head(NULL);
1513 set_vframe_array_last(NULL);
1514 set_deferred_locals(NULL);
1515 set_deopt_mark(NULL);
1516 set_deopt_compiled_method(NULL);
1517 clear_must_deopt_id();
1518 set_monitor_chunks(NULL);
1519 set_next(NULL);
1520 _on_thread_list = false;
1521 set_thread_state(_thread_new);
1522 _terminated = _not_terminated;
1523 _privileged_stack_top = NULL;
1524 _array_for_gc = NULL;
1525 _suspend_equivalent = false;
1526 _in_deopt_handler = 0;
1527 _doing_unsafe_access = false;
1528 _stack_guard_state = stack_guard_unused;
1529 #if INCLUDE_JVMCI
1530 _pending_monitorenter = false;
1531 _pending_deoptimization = -1;
1532 _pending_failed_speculation = NULL;
1533 _pending_transfer_to_interpreter = false;
1534 _adjusting_comp_level = false;
1535 _jvmci._alternate_call_target = NULL;
1536 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1537 if (JVMCICounterSize > 0) {
1538 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1539 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1540 } else {
1541 _jvmci_counters = NULL;
1542 }
1543 #endif // INCLUDE_JVMCI
1544 _reserved_stack_activation = NULL; // stack base not known yet
1545 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1546 _exception_pc = 0;
1547 _exception_handler_pc = 0;
1548 _is_method_handle_return = 0;
1549 _jvmti_thread_state= NULL;
1550 _should_post_on_exceptions_flag = JNI_FALSE;
1551 _jvmti_get_loaded_classes_closure = NULL;
1552 _interp_only_mode = 0;
1553 _special_runtime_exit_condition = _no_async_condition;
1554 _pending_async_exception = NULL;
1555 _thread_stat = NULL;
1556 _thread_stat = new ThreadStatistics();
1557 _blocked_on_compilation = false;
1558 _jni_active_critical = 0;
1559 _pending_jni_exception_check_fn = NULL;
1560 _do_not_unlock_if_synchronized = false;
1561 _cached_monitor_info = NULL;
1562 _parker = Parker::Allocate(this);
1563
1564 #ifndef PRODUCT
1565 _jmp_ring_index = 0;
1566 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1567 record_jump(NULL, NULL, NULL, 0);
1568 }
1569 #endif // PRODUCT
1570
1571 // Setup safepoint state info for this thread
1572 ThreadSafepointState::create(this);
1573
1574 debug_only(_java_call_counter = 0);
1575
1576 // JVMTI PopFrame support
1577 _popframe_condition = popframe_inactive;
1578 _popframe_preserved_args = NULL;
1579 _popframe_preserved_args_size = 0;
1580 _frames_to_pop_failed_realloc = 0;
1581
1582 if (SafepointMechanism::uses_thread_local_poll()) {
1583 SafepointMechanism::initialize_header(this);
1584 }
1585
1586 pd_initialize();
1587 }
1588
1589 #if INCLUDE_ALL_GCS
1590 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1591 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1592 #endif // INCLUDE_ALL_GCS
1593
1594 JavaThread::JavaThread(bool is_attaching_via_jni) :
1595 Thread()
1596 #if INCLUDE_ALL_GCS
1597 , _satb_mark_queue(&_satb_mark_queue_set),
1598 _dirty_card_queue(&_dirty_card_queue_set)
1599 #endif // INCLUDE_ALL_GCS
1600 {
1601 initialize();
1602 if (is_attaching_via_jni) {
1603 _jni_attach_state = _attaching_via_jni;
1604 } else {
1605 _jni_attach_state = _not_attaching_via_jni;
1606 }
1607 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1608 }
1609
1610 bool JavaThread::reguard_stack(address cur_sp) {
1611 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1612 && _stack_guard_state != stack_guard_reserved_disabled) {
1613 return true; // Stack already guarded or guard pages not needed.
1614 }
1615
1616 if (register_stack_overflow()) {
1617 // For those architectures which have separate register and
1618 // memory stacks, we must check the register stack to see if
1619 // it has overflowed.
1620 return false;
1621 }
1622
1623 // Java code never executes within the yellow zone: the latter is only
1624 // there to provoke an exception during stack banging. If java code
1625 // is executing there, either StackShadowPages should be larger, or
1626 // some exception code in c1, c2 or the interpreter isn't unwinding
1627 // when it should.
1628 guarantee(cur_sp > stack_reserved_zone_base(),
1629 "not enough space to reguard - increase StackShadowPages");
1630 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1631 enable_stack_yellow_reserved_zone();
1632 if (reserved_stack_activation() != stack_base()) {
1633 set_reserved_stack_activation(stack_base());
1634 }
1635 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1636 set_reserved_stack_activation(stack_base());
1637 enable_stack_reserved_zone();
1638 }
1639 return true;
1640 }
1641
1642 bool JavaThread::reguard_stack(void) {
1643 return reguard_stack(os::current_stack_pointer());
1644 }
1645
1646
1647 void JavaThread::block_if_vm_exited() {
1648 if (_terminated == _vm_exited) {
1649 // _vm_exited is set at safepoint, and Threads_lock is never released
1650 // we will block here forever
1651 Threads_lock->lock_without_safepoint_check();
1652 ShouldNotReachHere();
1653 }
1654 }
1655
1656
1657 // Remove this ifdef when C1 is ported to the compiler interface.
1658 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1659 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1660
1661 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1662 Thread()
1663 #if INCLUDE_ALL_GCS
1664 , _satb_mark_queue(&_satb_mark_queue_set),
1665 _dirty_card_queue(&_dirty_card_queue_set)
1666 #endif // INCLUDE_ALL_GCS
1667 {
1668 initialize();
1669 _jni_attach_state = _not_attaching_via_jni;
1670 set_entry_point(entry_point);
1671 // Create the native thread itself.
1672 // %note runtime_23
1673 os::ThreadType thr_type = os::java_thread;
1674 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1675 os::java_thread;
1676 os::create_thread(this, thr_type, stack_sz);
1677 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1678 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1679 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1680 // the exception consists of creating the exception object & initializing it, initialization
1681 // will leave the VM via a JavaCall and then all locks must be unlocked).
1682 //
1683 // The thread is still suspended when we reach here. Thread must be explicit started
1684 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1685 // by calling Threads:add. The reason why this is not done here, is because the thread
1686 // object must be fully initialized (take a look at JVM_Start)
1687 }
1688
1689 JavaThread::~JavaThread() {
1690
1691 // JSR166 -- return the parker to the free list
1692 Parker::Release(_parker);
1693 _parker = NULL;
1694
1695 // Free any remaining previous UnrollBlock
1696 vframeArray* old_array = vframe_array_last();
1697
1698 if (old_array != NULL) {
1699 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1700 old_array->set_unroll_block(NULL);
1701 delete old_info;
1702 delete old_array;
1703 }
1704
1705 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1706 if (deferred != NULL) {
1707 // This can only happen if thread is destroyed before deoptimization occurs.
1708 assert(deferred->length() != 0, "empty array!");
1709 do {
1710 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1711 deferred->remove_at(0);
1712 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1713 delete dlv;
1714 } while (deferred->length() != 0);
1715 delete deferred;
1716 }
1717
1718 // All Java related clean up happens in exit
1719 ThreadSafepointState::destroy(this);
1720 if (_thread_stat != NULL) delete _thread_stat;
1721
1722 #if INCLUDE_JVMCI
1723 if (JVMCICounterSize > 0) {
1724 if (jvmci_counters_include(this)) {
1725 for (int i = 0; i < JVMCICounterSize; i++) {
1726 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1727 }
1728 }
1729 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1730 }
1731 #endif // INCLUDE_JVMCI
1732 }
1733
1734
1735 // The first routine called by a new Java thread
1736 void JavaThread::run() {
1737 // initialize thread-local alloc buffer related fields
1738 this->initialize_tlab();
1739
1740 // used to test validity of stack trace backs
1741 this->record_base_of_stack_pointer();
1742
1743 // Record real stack base and size.
1744 this->record_stack_base_and_size();
1745
1746 this->create_stack_guard_pages();
1747
1748 this->cache_global_variables();
1749
1750 // Thread is now sufficient initialized to be handled by the safepoint code as being
1751 // in the VM. Change thread state from _thread_new to _thread_in_vm
1752 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1753
1754 assert(JavaThread::current() == this, "sanity check");
1755 assert(!Thread::current()->owns_locks(), "sanity check");
1756
1757 DTRACE_THREAD_PROBE(start, this);
1758
1759 // This operation might block. We call that after all safepoint checks for a new thread has
1760 // been completed.
1761 this->set_active_handles(JNIHandleBlock::allocate_block());
1762
1763 if (JvmtiExport::should_post_thread_life()) {
1764 JvmtiExport::post_thread_start(this);
1765 }
1766
1767 EventThreadStart event;
1768 if (event.should_commit()) {
1769 event.set_thread(THREAD_TRACE_ID(this));
1770 event.commit();
1771 }
1772
1773 // We call another function to do the rest so we are sure that the stack addresses used
1774 // from there will be lower than the stack base just computed
1775 thread_main_inner();
1776
1777 // Note, thread is no longer valid at this point!
1778 }
1779
1780
1781 void JavaThread::thread_main_inner() {
1782 assert(JavaThread::current() == this, "sanity check");
1783 assert(this->threadObj() != NULL, "just checking");
1784
1785 // Execute thread entry point unless this thread has a pending exception
1786 // or has been stopped before starting.
1787 // Note: Due to JVM_StopThread we can have pending exceptions already!
1788 if (!this->has_pending_exception() &&
1789 !java_lang_Thread::is_stillborn(this->threadObj())) {
1790 {
1791 ResourceMark rm(this);
1792 this->set_native_thread_name(this->get_thread_name());
1793 }
1794 HandleMark hm(this);
1795 this->entry_point()(this, this);
1796 }
1797
1798 DTRACE_THREAD_PROBE(stop, this);
1799
1800 this->exit(false);
1801 this->smr_delete();
1802 }
1803
1804
1805 static void ensure_join(JavaThread* thread) {
1806 // We do not need to grab the Threads_lock, since we are operating on ourself.
1807 Handle threadObj(thread, thread->threadObj());
1808 assert(threadObj.not_null(), "java thread object must exist");
1809 ObjectLocker lock(threadObj, thread);
1810 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1811 thread->clear_pending_exception();
1812 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1813 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1814 // Clear the native thread instance - this makes isAlive return false and allows the join()
1815 // to complete once we've done the notify_all below
1816 java_lang_Thread::set_thread(threadObj(), NULL);
1817 lock.notify_all(thread);
1818 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1819 thread->clear_pending_exception();
1820 }
1821
1822
1823 // For any new cleanup additions, please check to see if they need to be applied to
1824 // cleanup_failed_attach_current_thread as well.
1825 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1826 assert(this == JavaThread::current(), "thread consistency check");
1827
1828 elapsedTimer _timer_exit_phase1;
1829 elapsedTimer _timer_exit_phase2;
1830 elapsedTimer _timer_exit_phase3;
1831 elapsedTimer _timer_exit_phase4;
1832
1833 if (log_is_enabled(Debug, os, thread, timer)) {
1834 _timer_exit_phase1.start();
1835 }
1836
1837 HandleMark hm(this);
1838 Handle uncaught_exception(this, this->pending_exception());
1839 this->clear_pending_exception();
1840 Handle threadObj(this, this->threadObj());
1841 assert(threadObj.not_null(), "Java thread object should be created");
1842
1843 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1844 {
1845 EXCEPTION_MARK;
1846
1847 CLEAR_PENDING_EXCEPTION;
1848 }
1849 if (!destroy_vm) {
1850 if (uncaught_exception.not_null()) {
1851 EXCEPTION_MARK;
1852 // Call method Thread.dispatchUncaughtException().
1853 Klass* thread_klass = SystemDictionary::Thread_klass();
1854 JavaValue result(T_VOID);
1855 JavaCalls::call_virtual(&result,
1856 threadObj, thread_klass,
1857 vmSymbols::dispatchUncaughtException_name(),
1858 vmSymbols::throwable_void_signature(),
1859 uncaught_exception,
1860 THREAD);
1861 if (HAS_PENDING_EXCEPTION) {
1862 ResourceMark rm(this);
1863 jio_fprintf(defaultStream::error_stream(),
1864 "\nException: %s thrown from the UncaughtExceptionHandler"
1865 " in thread \"%s\"\n",
1866 pending_exception()->klass()->external_name(),
1867 get_thread_name());
1868 CLEAR_PENDING_EXCEPTION;
1869 }
1870 }
1871
1872 // Called before the java thread exit since we want to read info
1873 // from java_lang_Thread object
1874 EventThreadEnd event;
1875 if (event.should_commit()) {
1876 event.set_thread(THREAD_TRACE_ID(this));
1877 event.commit();
1878 }
1879
1880 // Call after last event on thread
1881 EVENT_THREAD_EXIT(this);
1882
1883 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1884 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1885 // is deprecated anyhow.
1886 if (!is_Compiler_thread()) {
1887 int count = 3;
1888 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1889 EXCEPTION_MARK;
1890 JavaValue result(T_VOID);
1891 Klass* thread_klass = SystemDictionary::Thread_klass();
1892 JavaCalls::call_virtual(&result,
1893 threadObj, thread_klass,
1894 vmSymbols::exit_method_name(),
1895 vmSymbols::void_method_signature(),
1896 THREAD);
1897 CLEAR_PENDING_EXCEPTION;
1898 }
1899 }
1900 // notify JVMTI
1901 if (JvmtiExport::should_post_thread_life()) {
1902 JvmtiExport::post_thread_end(this);
1903 }
1904
1905 // We have notified the agents that we are exiting, before we go on,
1906 // we must check for a pending external suspend request and honor it
1907 // in order to not surprise the thread that made the suspend request.
1908 while (true) {
1909 {
1910 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1911 if (!is_external_suspend()) {
1912 set_terminated(_thread_exiting);
1913 ThreadService::current_thread_exiting(this);
1914 break;
1915 }
1916 // Implied else:
1917 // Things get a little tricky here. We have a pending external
1918 // suspend request, but we are holding the SR_lock so we
1919 // can't just self-suspend. So we temporarily drop the lock
1920 // and then self-suspend.
1921 }
1922
1923 ThreadBlockInVM tbivm(this);
1924 java_suspend_self();
1925
1926 // We're done with this suspend request, but we have to loop around
1927 // and check again. Eventually we will get SR_lock without a pending
1928 // external suspend request and will be able to mark ourselves as
1929 // exiting.
1930 }
1931 // no more external suspends are allowed at this point
1932 } else {
1933 // before_exit() has already posted JVMTI THREAD_END events
1934 }
1935
1936 if (log_is_enabled(Debug, os, thread, timer)) {
1937 _timer_exit_phase1.stop();
1938 _timer_exit_phase2.start();
1939 }
1940 // Notify waiters on thread object. This has to be done after exit() is called
1941 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1942 // group should have the destroyed bit set before waiters are notified).
1943 ensure_join(this);
1944 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1945
1946 if (log_is_enabled(Debug, os, thread, timer)) {
1947 _timer_exit_phase2.stop();
1948 _timer_exit_phase3.start();
1949 }
1950 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1951 // held by this thread must be released. The spec does not distinguish
1952 // between JNI-acquired and regular Java monitors. We can only see
1953 // regular Java monitors here if monitor enter-exit matching is broken.
1954 //
1955 // Optionally release any monitors for regular JavaThread exits. This
1956 // is provided as a work around for any bugs in monitor enter-exit
1957 // matching. This can be expensive so it is not enabled by default.
1958 //
1959 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1960 // ObjectSynchronizer::release_monitors_owned_by_thread().
1961 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1962 // Sanity check even though JNI DetachCurrentThread() would have
1963 // returned JNI_ERR if there was a Java frame. JavaThread exit
1964 // should be done executing Java code by the time we get here.
1965 assert(!this->has_last_Java_frame(),
1966 "should not have a Java frame when detaching or exiting");
1967 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1968 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1969 }
1970
1971 // These things needs to be done while we are still a Java Thread. Make sure that thread
1972 // is in a consistent state, in case GC happens
1973 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1974
1975 if (active_handles() != NULL) {
1976 JNIHandleBlock* block = active_handles();
1977 set_active_handles(NULL);
1978 JNIHandleBlock::release_block(block);
1979 }
1980
1981 if (free_handle_block() != NULL) {
1982 JNIHandleBlock* block = free_handle_block();
1983 set_free_handle_block(NULL);
1984 JNIHandleBlock::release_block(block);
1985 }
1986
1987 // These have to be removed while this is still a valid thread.
1988 remove_stack_guard_pages();
1989
1990 if (UseTLAB) {
1991 tlab().make_parsable(true); // retire TLAB
1992 }
1993
1994 if (JvmtiEnv::environments_might_exist()) {
1995 JvmtiExport::cleanup_thread(this);
1996 }
1997
1998 // We must flush any deferred card marks before removing a thread from
1999 // the list of active threads.
2000 Universe::heap()->flush_deferred_store_barrier(this);
2001 assert(deferred_card_mark().is_empty(), "Should have been flushed");
2002
2003 #if INCLUDE_ALL_GCS
2004 // We must flush the G1-related buffers before removing a thread
2005 // from the list of active threads. We must do this after any deferred
2006 // card marks have been flushed (above) so that any entries that are
2007 // added to the thread's dirty card queue as a result are not lost.
2008 if (UseG1GC) {
2009 flush_barrier_queues();
2010 }
2011 #endif // INCLUDE_ALL_GCS
2012
2013 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2014 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2015 os::current_thread_id());
2016
2017 if (log_is_enabled(Debug, os, thread, timer)) {
2018 _timer_exit_phase3.stop();
2019 _timer_exit_phase4.start();
2020 }
2021 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2022 Threads::remove(this);
2023
2024 if (log_is_enabled(Debug, os, thread, timer)) {
2025 _timer_exit_phase4.stop();
2026 ResourceMark rm(this);
2027 log_debug(os, thread, timer)("name='%s'"
2028 ", exit-phase1=" JLONG_FORMAT
2029 ", exit-phase2=" JLONG_FORMAT
2030 ", exit-phase3=" JLONG_FORMAT
2031 ", exit-phase4=" JLONG_FORMAT,
2032 get_thread_name(),
2033 _timer_exit_phase1.milliseconds(),
2034 _timer_exit_phase2.milliseconds(),
2035 _timer_exit_phase3.milliseconds(),
2036 _timer_exit_phase4.milliseconds());
2037 }
2038 }
2039
2040 #if INCLUDE_ALL_GCS
2041 // Flush G1-related queues.
2042 void JavaThread::flush_barrier_queues() {
2043 satb_mark_queue().flush();
2044 dirty_card_queue().flush();
2045 }
2046
2047 void JavaThread::initialize_queues() {
2048 assert(!SafepointSynchronize::is_at_safepoint(),
2049 "we should not be at a safepoint");
2050
2051 SATBMarkQueue& satb_queue = satb_mark_queue();
2052 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2053 // The SATB queue should have been constructed with its active
2054 // field set to false.
2055 assert(!satb_queue.is_active(), "SATB queue should not be active");
2056 assert(satb_queue.is_empty(), "SATB queue should be empty");
2057 // If we are creating the thread during a marking cycle, we should
2058 // set the active field of the SATB queue to true.
2059 if (satb_queue_set.is_active()) {
2060 satb_queue.set_active(true);
2061 }
2062
2063 DirtyCardQueue& dirty_queue = dirty_card_queue();
2064 // The dirty card queue should have been constructed with its
2065 // active field set to true.
2066 assert(dirty_queue.is_active(), "dirty card queue should be active");
2067 }
2068 #endif // INCLUDE_ALL_GCS
2069
2070 void JavaThread::cleanup_failed_attach_current_thread() {
2071 if (active_handles() != NULL) {
2072 JNIHandleBlock* block = active_handles();
2073 set_active_handles(NULL);
2074 JNIHandleBlock::release_block(block);
2075 }
2076
2077 if (free_handle_block() != NULL) {
2078 JNIHandleBlock* block = free_handle_block();
2079 set_free_handle_block(NULL);
2080 JNIHandleBlock::release_block(block);
2081 }
2082
2083 // These have to be removed while this is still a valid thread.
2084 remove_stack_guard_pages();
2085
2086 if (UseTLAB) {
2087 tlab().make_parsable(true); // retire TLAB, if any
2088 }
2089
2090 #if INCLUDE_ALL_GCS
2091 if (UseG1GC) {
2092 flush_barrier_queues();
2093 }
2094 #endif // INCLUDE_ALL_GCS
2095
2096 Threads::remove(this);
2097 this->smr_delete();
2098 }
2099
2100
2101
2102
2103 JavaThread* JavaThread::active() {
2104 Thread* thread = Thread::current();
2105 if (thread->is_Java_thread()) {
2106 return (JavaThread*) thread;
2107 } else {
2108 assert(thread->is_VM_thread(), "this must be a vm thread");
2109 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2110 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2111 assert(ret->is_Java_thread(), "must be a Java thread");
2112 return ret;
2113 }
2114 }
2115
2116 bool JavaThread::is_lock_owned(address adr) const {
2117 if (Thread::is_lock_owned(adr)) return true;
2118
2119 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2120 if (chunk->contains(adr)) return true;
2121 }
2122
2123 return false;
2124 }
2125
2126
2127 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2128 chunk->set_next(monitor_chunks());
2129 set_monitor_chunks(chunk);
2130 }
2131
2132 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2133 guarantee(monitor_chunks() != NULL, "must be non empty");
2134 if (monitor_chunks() == chunk) {
2135 set_monitor_chunks(chunk->next());
2136 } else {
2137 MonitorChunk* prev = monitor_chunks();
2138 while (prev->next() != chunk) prev = prev->next();
2139 prev->set_next(chunk->next());
2140 }
2141 }
2142
2143 // JVM support.
2144
2145 // Note: this function shouldn't block if it's called in
2146 // _thread_in_native_trans state (such as from
2147 // check_special_condition_for_native_trans()).
2148 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2149
2150 if (has_last_Java_frame() && has_async_condition()) {
2151 // If we are at a polling page safepoint (not a poll return)
2152 // then we must defer async exception because live registers
2153 // will be clobbered by the exception path. Poll return is
2154 // ok because the call we a returning from already collides
2155 // with exception handling registers and so there is no issue.
2156 // (The exception handling path kills call result registers but
2157 // this is ok since the exception kills the result anyway).
2158
2159 if (is_at_poll_safepoint()) {
2160 // if the code we are returning to has deoptimized we must defer
2161 // the exception otherwise live registers get clobbered on the
2162 // exception path before deoptimization is able to retrieve them.
2163 //
2164 RegisterMap map(this, false);
2165 frame caller_fr = last_frame().sender(&map);
2166 assert(caller_fr.is_compiled_frame(), "what?");
2167 if (caller_fr.is_deoptimized_frame()) {
2168 log_info(exceptions)("deferred async exception at compiled safepoint");
2169 return;
2170 }
2171 }
2172 }
2173
2174 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2175 if (condition == _no_async_condition) {
2176 // Conditions have changed since has_special_runtime_exit_condition()
2177 // was called:
2178 // - if we were here only because of an external suspend request,
2179 // then that was taken care of above (or cancelled) so we are done
2180 // - if we were here because of another async request, then it has
2181 // been cleared between the has_special_runtime_exit_condition()
2182 // and now so again we are done
2183 return;
2184 }
2185
2186 // Check for pending async. exception
2187 if (_pending_async_exception != NULL) {
2188 // Only overwrite an already pending exception, if it is not a threadDeath.
2189 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2190
2191 // We cannot call Exceptions::_throw(...) here because we cannot block
2192 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2193
2194 LogTarget(Info, exceptions) lt;
2195 if (lt.is_enabled()) {
2196 ResourceMark rm;
2197 LogStream ls(lt);
2198 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2199 if (has_last_Java_frame()) {
2200 frame f = last_frame();
2201 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2202 }
2203 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2204 }
2205 _pending_async_exception = NULL;
2206 clear_has_async_exception();
2207 }
2208 }
2209
2210 if (check_unsafe_error &&
2211 condition == _async_unsafe_access_error && !has_pending_exception()) {
2212 condition = _no_async_condition; // done
2213 switch (thread_state()) {
2214 case _thread_in_vm: {
2215 JavaThread* THREAD = this;
2216 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2217 }
2218 case _thread_in_native: {
2219 ThreadInVMfromNative tiv(this);
2220 JavaThread* THREAD = this;
2221 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2222 }
2223 case _thread_in_Java: {
2224 ThreadInVMfromJava tiv(this);
2225 JavaThread* THREAD = this;
2226 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2227 }
2228 default:
2229 ShouldNotReachHere();
2230 }
2231 }
2232
2233 assert(condition == _no_async_condition || has_pending_exception() ||
2234 (!check_unsafe_error && condition == _async_unsafe_access_error),
2235 "must have handled the async condition, if no exception");
2236 }
2237
2238 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2239 //
2240 // Check for pending external suspend. Internal suspend requests do
2241 // not use handle_special_runtime_exit_condition().
2242 // If JNIEnv proxies are allowed, don't self-suspend if the target
2243 // thread is not the current thread. In older versions of jdbx, jdbx
2244 // threads could call into the VM with another thread's JNIEnv so we
2245 // can be here operating on behalf of a suspended thread (4432884).
2246 bool do_self_suspend = is_external_suspend_with_lock();
2247 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2248 //
2249 // Because thread is external suspended the safepoint code will count
2250 // thread as at a safepoint. This can be odd because we can be here
2251 // as _thread_in_Java which would normally transition to _thread_blocked
2252 // at a safepoint. We would like to mark the thread as _thread_blocked
2253 // before calling java_suspend_self like all other callers of it but
2254 // we must then observe proper safepoint protocol. (We can't leave
2255 // _thread_blocked with a safepoint in progress). However we can be
2256 // here as _thread_in_native_trans so we can't use a normal transition
2257 // constructor/destructor pair because they assert on that type of
2258 // transition. We could do something like:
2259 //
2260 // JavaThreadState state = thread_state();
2261 // set_thread_state(_thread_in_vm);
2262 // {
2263 // ThreadBlockInVM tbivm(this);
2264 // java_suspend_self()
2265 // }
2266 // set_thread_state(_thread_in_vm_trans);
2267 // if (safepoint) block;
2268 // set_thread_state(state);
2269 //
2270 // but that is pretty messy. Instead we just go with the way the
2271 // code has worked before and note that this is the only path to
2272 // java_suspend_self that doesn't put the thread in _thread_blocked
2273 // mode.
2274
2275 frame_anchor()->make_walkable(this);
2276 java_suspend_self();
2277
2278 // We might be here for reasons in addition to the self-suspend request
2279 // so check for other async requests.
2280 }
2281
2282 if (check_asyncs) {
2283 check_and_handle_async_exceptions();
2284 }
2285 #if INCLUDE_TRACE
2286 if (is_trace_suspend()) {
2287 TRACE_SUSPEND_THREAD(this);
2288 }
2289 #endif
2290 }
2291
2292 void JavaThread::send_thread_stop(oop java_throwable) {
2293 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2294 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2295 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2296
2297 // Do not throw asynchronous exceptions against the compiler thread
2298 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2299 if (!can_call_java()) return;
2300
2301 {
2302 // Actually throw the Throwable against the target Thread - however
2303 // only if there is no thread death exception installed already.
2304 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2305 // If the topmost frame is a runtime stub, then we are calling into
2306 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2307 // must deoptimize the caller before continuing, as the compiled exception handler table
2308 // may not be valid
2309 if (has_last_Java_frame()) {
2310 frame f = last_frame();
2311 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2312 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2313 RegisterMap reg_map(this, UseBiasedLocking);
2314 frame compiled_frame = f.sender(®_map);
2315 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2316 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2317 }
2318 }
2319 }
2320
2321 // Set async. pending exception in thread.
2322 set_pending_async_exception(java_throwable);
2323
2324 if (log_is_enabled(Info, exceptions)) {
2325 ResourceMark rm;
2326 log_info(exceptions)("Pending Async. exception installed of type: %s",
2327 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2328 }
2329 // for AbortVMOnException flag
2330 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2331 }
2332 }
2333
2334
2335 // Interrupt thread so it will wake up from a potential wait()
2336 Thread::interrupt(this);
2337 }
2338
2339 // External suspension mechanism.
2340 //
2341 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2342 // to any VM_locks and it is at a transition
2343 // Self-suspension will happen on the transition out of the vm.
2344 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2345 //
2346 // Guarantees on return:
2347 // + Target thread will not execute any new bytecode (that's why we need to
2348 // force a safepoint)
2349 // + Target thread will not enter any new monitors
2350 //
2351 void JavaThread::java_suspend() {
2352 ThreadsListHandle tlh;
2353 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2354 return;
2355 }
2356
2357 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2358 if (!is_external_suspend()) {
2359 // a racing resume has cancelled us; bail out now
2360 return;
2361 }
2362
2363 // suspend is done
2364 uint32_t debug_bits = 0;
2365 // Warning: is_ext_suspend_completed() may temporarily drop the
2366 // SR_lock to allow the thread to reach a stable thread state if
2367 // it is currently in a transient thread state.
2368 if (is_ext_suspend_completed(false /* !called_by_wait */,
2369 SuspendRetryDelay, &debug_bits)) {
2370 return;
2371 }
2372 }
2373
2374 VM_ThreadSuspend vm_suspend;
2375 VMThread::execute(&vm_suspend);
2376 }
2377
2378 // Part II of external suspension.
2379 // A JavaThread self suspends when it detects a pending external suspend
2380 // request. This is usually on transitions. It is also done in places
2381 // where continuing to the next transition would surprise the caller,
2382 // e.g., monitor entry.
2383 //
2384 // Returns the number of times that the thread self-suspended.
2385 //
2386 // Note: DO NOT call java_suspend_self() when you just want to block current
2387 // thread. java_suspend_self() is the second stage of cooperative
2388 // suspension for external suspend requests and should only be used
2389 // to complete an external suspend request.
2390 //
2391 int JavaThread::java_suspend_self() {
2392 int ret = 0;
2393
2394 // we are in the process of exiting so don't suspend
2395 if (is_exiting()) {
2396 clear_external_suspend();
2397 return ret;
2398 }
2399
2400 assert(_anchor.walkable() ||
2401 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2402 "must have walkable stack");
2403
2404 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2405
2406 assert(!this->is_ext_suspended(),
2407 "a thread trying to self-suspend should not already be suspended");
2408
2409 if (this->is_suspend_equivalent()) {
2410 // If we are self-suspending as a result of the lifting of a
2411 // suspend equivalent condition, then the suspend_equivalent
2412 // flag is not cleared until we set the ext_suspended flag so
2413 // that wait_for_ext_suspend_completion() returns consistent
2414 // results.
2415 this->clear_suspend_equivalent();
2416 }
2417
2418 // A racing resume may have cancelled us before we grabbed SR_lock
2419 // above. Or another external suspend request could be waiting for us
2420 // by the time we return from SR_lock()->wait(). The thread
2421 // that requested the suspension may already be trying to walk our
2422 // stack and if we return now, we can change the stack out from under
2423 // it. This would be a "bad thing (TM)" and cause the stack walker
2424 // to crash. We stay self-suspended until there are no more pending
2425 // external suspend requests.
2426 while (is_external_suspend()) {
2427 ret++;
2428 this->set_ext_suspended();
2429
2430 // _ext_suspended flag is cleared by java_resume()
2431 while (is_ext_suspended()) {
2432 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2433 }
2434 }
2435
2436 return ret;
2437 }
2438
2439 #ifdef ASSERT
2440 // verify the JavaThread has not yet been published in the Threads::list, and
2441 // hence doesn't need protection from concurrent access at this stage
2442 void JavaThread::verify_not_published() {
2443 ThreadsListHandle tlh;
2444 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2445 }
2446 #endif
2447
2448 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2449 // progress or when _suspend_flags is non-zero.
2450 // Current thread needs to self-suspend if there is a suspend request and/or
2451 // block if a safepoint is in progress.
2452 // Async exception ISN'T checked.
2453 // Note only the ThreadInVMfromNative transition can call this function
2454 // directly and when thread state is _thread_in_native_trans
2455 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2456 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2457
2458 JavaThread *curJT = JavaThread::current();
2459 bool do_self_suspend = thread->is_external_suspend();
2460
2461 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2462
2463 // If JNIEnv proxies are allowed, don't self-suspend if the target
2464 // thread is not the current thread. In older versions of jdbx, jdbx
2465 // threads could call into the VM with another thread's JNIEnv so we
2466 // can be here operating on behalf of a suspended thread (4432884).
2467 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2468 JavaThreadState state = thread->thread_state();
2469
2470 // We mark this thread_blocked state as a suspend-equivalent so
2471 // that a caller to is_ext_suspend_completed() won't be confused.
2472 // The suspend-equivalent state is cleared by java_suspend_self().
2473 thread->set_suspend_equivalent();
2474
2475 // If the safepoint code sees the _thread_in_native_trans state, it will
2476 // wait until the thread changes to other thread state. There is no
2477 // guarantee on how soon we can obtain the SR_lock and complete the
2478 // self-suspend request. It would be a bad idea to let safepoint wait for
2479 // too long. Temporarily change the state to _thread_blocked to
2480 // let the VM thread know that this thread is ready for GC. The problem
2481 // of changing thread state is that safepoint could happen just after
2482 // java_suspend_self() returns after being resumed, and VM thread will
2483 // see the _thread_blocked state. We must check for safepoint
2484 // after restoring the state and make sure we won't leave while a safepoint
2485 // is in progress.
2486 thread->set_thread_state(_thread_blocked);
2487 thread->java_suspend_self();
2488 thread->set_thread_state(state);
2489
2490 InterfaceSupport::serialize_thread_state_with_handler(thread);
2491 }
2492
2493 SafepointMechanism::block_if_requested(curJT);
2494
2495 if (thread->is_deopt_suspend()) {
2496 thread->clear_deopt_suspend();
2497 RegisterMap map(thread, false);
2498 frame f = thread->last_frame();
2499 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2500 f = f.sender(&map);
2501 }
2502 if (f.id() == thread->must_deopt_id()) {
2503 thread->clear_must_deopt_id();
2504 f.deoptimize(thread);
2505 } else {
2506 fatal("missed deoptimization!");
2507 }
2508 }
2509 #if INCLUDE_TRACE
2510 if (thread->is_trace_suspend()) {
2511 TRACE_SUSPEND_THREAD(thread);
2512 }
2513 #endif
2514 }
2515
2516 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2517 // progress or when _suspend_flags is non-zero.
2518 // Current thread needs to self-suspend if there is a suspend request and/or
2519 // block if a safepoint is in progress.
2520 // Also check for pending async exception (not including unsafe access error).
2521 // Note only the native==>VM/Java barriers can call this function and when
2522 // thread state is _thread_in_native_trans.
2523 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2524 check_safepoint_and_suspend_for_native_trans(thread);
2525
2526 if (thread->has_async_exception()) {
2527 // We are in _thread_in_native_trans state, don't handle unsafe
2528 // access error since that may block.
2529 thread->check_and_handle_async_exceptions(false);
2530 }
2531 }
2532
2533 // This is a variant of the normal
2534 // check_special_condition_for_native_trans with slightly different
2535 // semantics for use by critical native wrappers. It does all the
2536 // normal checks but also performs the transition back into
2537 // thread_in_Java state. This is required so that critical natives
2538 // can potentially block and perform a GC if they are the last thread
2539 // exiting the GCLocker.
2540 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2541 check_special_condition_for_native_trans(thread);
2542
2543 // Finish the transition
2544 thread->set_thread_state(_thread_in_Java);
2545
2546 if (thread->do_critical_native_unlock()) {
2547 ThreadInVMfromJavaNoAsyncException tiv(thread);
2548 GCLocker::unlock_critical(thread);
2549 thread->clear_critical_native_unlock();
2550 }
2551 }
2552
2553 // We need to guarantee the Threads_lock here, since resumes are not
2554 // allowed during safepoint synchronization
2555 // Can only resume from an external suspension
2556 void JavaThread::java_resume() {
2557 assert_locked_or_safepoint(Threads_lock);
2558
2559 // Sanity check: thread is gone, has started exiting or the thread
2560 // was not externally suspended.
2561 ThreadsListHandle tlh;
2562 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2563 return;
2564 }
2565
2566 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2567
2568 clear_external_suspend();
2569
2570 if (is_ext_suspended()) {
2571 clear_ext_suspended();
2572 SR_lock()->notify_all();
2573 }
2574 }
2575
2576 size_t JavaThread::_stack_red_zone_size = 0;
2577 size_t JavaThread::_stack_yellow_zone_size = 0;
2578 size_t JavaThread::_stack_reserved_zone_size = 0;
2579 size_t JavaThread::_stack_shadow_zone_size = 0;
2580
2581 void JavaThread::create_stack_guard_pages() {
2582 if (!os::uses_stack_guard_pages() ||
2583 _stack_guard_state != stack_guard_unused ||
2584 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2585 log_info(os, thread)("Stack guard page creation for thread "
2586 UINTX_FORMAT " disabled", os::current_thread_id());
2587 return;
2588 }
2589 address low_addr = stack_end();
2590 size_t len = stack_guard_zone_size();
2591
2592 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2593 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2594
2595 int must_commit = os::must_commit_stack_guard_pages();
2596 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2597
2598 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2599 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2600 return;
2601 }
2602
2603 if (os::guard_memory((char *) low_addr, len)) {
2604 _stack_guard_state = stack_guard_enabled;
2605 } else {
2606 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2607 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2608 if (os::uncommit_memory((char *) low_addr, len)) {
2609 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2610 }
2611 return;
2612 }
2613
2614 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2615 PTR_FORMAT "-" PTR_FORMAT ".",
2616 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2617 }
2618
2619 void JavaThread::remove_stack_guard_pages() {
2620 assert(Thread::current() == this, "from different thread");
2621 if (_stack_guard_state == stack_guard_unused) return;
2622 address low_addr = stack_end();
2623 size_t len = stack_guard_zone_size();
2624
2625 if (os::must_commit_stack_guard_pages()) {
2626 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2627 _stack_guard_state = stack_guard_unused;
2628 } else {
2629 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2630 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2631 return;
2632 }
2633 } else {
2634 if (_stack_guard_state == stack_guard_unused) return;
2635 if (os::unguard_memory((char *) low_addr, len)) {
2636 _stack_guard_state = stack_guard_unused;
2637 } else {
2638 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2639 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2640 return;
2641 }
2642 }
2643
2644 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2645 PTR_FORMAT "-" PTR_FORMAT ".",
2646 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2647 }
2648
2649 void JavaThread::enable_stack_reserved_zone() {
2650 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2651 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2652
2653 // The base notation is from the stack's point of view, growing downward.
2654 // We need to adjust it to work correctly with guard_memory()
2655 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2656
2657 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2658 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2659
2660 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2661 _stack_guard_state = stack_guard_enabled;
2662 } else {
2663 warning("Attempt to guard stack reserved zone failed.");
2664 }
2665 enable_register_stack_guard();
2666 }
2667
2668 void JavaThread::disable_stack_reserved_zone() {
2669 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2670 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2671
2672 // Simply return if called for a thread that does not use guard pages.
2673 if (_stack_guard_state == stack_guard_unused) return;
2674
2675 // The base notation is from the stack's point of view, growing downward.
2676 // We need to adjust it to work correctly with guard_memory()
2677 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2678
2679 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2680 _stack_guard_state = stack_guard_reserved_disabled;
2681 } else {
2682 warning("Attempt to unguard stack reserved zone failed.");
2683 }
2684 disable_register_stack_guard();
2685 }
2686
2687 void JavaThread::enable_stack_yellow_reserved_zone() {
2688 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2689 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2690
2691 // The base notation is from the stacks point of view, growing downward.
2692 // We need to adjust it to work correctly with guard_memory()
2693 address base = stack_red_zone_base();
2694
2695 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2696 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2697
2698 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2699 _stack_guard_state = stack_guard_enabled;
2700 } else {
2701 warning("Attempt to guard stack yellow zone failed.");
2702 }
2703 enable_register_stack_guard();
2704 }
2705
2706 void JavaThread::disable_stack_yellow_reserved_zone() {
2707 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2708 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2709
2710 // Simply return if called for a thread that does not use guard pages.
2711 if (_stack_guard_state == stack_guard_unused) return;
2712
2713 // The base notation is from the stacks point of view, growing downward.
2714 // We need to adjust it to work correctly with guard_memory()
2715 address base = stack_red_zone_base();
2716
2717 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2718 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2719 } else {
2720 warning("Attempt to unguard stack yellow zone failed.");
2721 }
2722 disable_register_stack_guard();
2723 }
2724
2725 void JavaThread::enable_stack_red_zone() {
2726 // The base notation is from the stacks point of view, growing downward.
2727 // We need to adjust it to work correctly with guard_memory()
2728 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2729 address base = stack_red_zone_base() - stack_red_zone_size();
2730
2731 guarantee(base < stack_base(), "Error calculating stack red zone");
2732 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2733
2734 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2735 warning("Attempt to guard stack red zone failed.");
2736 }
2737 }
2738
2739 void JavaThread::disable_stack_red_zone() {
2740 // The base notation is from the stacks point of view, growing downward.
2741 // We need to adjust it to work correctly with guard_memory()
2742 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2743 address base = stack_red_zone_base() - stack_red_zone_size();
2744 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2745 warning("Attempt to unguard stack red zone failed.");
2746 }
2747 }
2748
2749 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2750 // ignore is there is no stack
2751 if (!has_last_Java_frame()) return;
2752 // traverse the stack frames. Starts from top frame.
2753 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2754 frame* fr = fst.current();
2755 f(fr, fst.register_map());
2756 }
2757 }
2758
2759
2760 #ifndef PRODUCT
2761 // Deoptimization
2762 // Function for testing deoptimization
2763 void JavaThread::deoptimize() {
2764 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2765 StackFrameStream fst(this, UseBiasedLocking);
2766 bool deopt = false; // Dump stack only if a deopt actually happens.
2767 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2768 // Iterate over all frames in the thread and deoptimize
2769 for (; !fst.is_done(); fst.next()) {
2770 if (fst.current()->can_be_deoptimized()) {
2771
2772 if (only_at) {
2773 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2774 // consists of comma or carriage return separated numbers so
2775 // search for the current bci in that string.
2776 address pc = fst.current()->pc();
2777 nmethod* nm = (nmethod*) fst.current()->cb();
2778 ScopeDesc* sd = nm->scope_desc_at(pc);
2779 char buffer[8];
2780 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2781 size_t len = strlen(buffer);
2782 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2783 while (found != NULL) {
2784 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2785 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2786 // Check that the bci found is bracketed by terminators.
2787 break;
2788 }
2789 found = strstr(found + 1, buffer);
2790 }
2791 if (!found) {
2792 continue;
2793 }
2794 }
2795
2796 if (DebugDeoptimization && !deopt) {
2797 deopt = true; // One-time only print before deopt
2798 tty->print_cr("[BEFORE Deoptimization]");
2799 trace_frames();
2800 trace_stack();
2801 }
2802 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2803 }
2804 }
2805
2806 if (DebugDeoptimization && deopt) {
2807 tty->print_cr("[AFTER Deoptimization]");
2808 trace_frames();
2809 }
2810 }
2811
2812
2813 // Make zombies
2814 void JavaThread::make_zombies() {
2815 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2816 if (fst.current()->can_be_deoptimized()) {
2817 // it is a Java nmethod
2818 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2819 nm->make_not_entrant();
2820 }
2821 }
2822 }
2823 #endif // PRODUCT
2824
2825
2826 void JavaThread::deoptimized_wrt_marked_nmethods() {
2827 if (!has_last_Java_frame()) return;
2828 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2829 StackFrameStream fst(this, UseBiasedLocking);
2830 for (; !fst.is_done(); fst.next()) {
2831 if (fst.current()->should_be_deoptimized()) {
2832 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2833 }
2834 }
2835 }
2836
2837
2838 // If the caller is a NamedThread, then remember, in the current scope,
2839 // the given JavaThread in its _processed_thread field.
2840 class RememberProcessedThread: public StackObj {
2841 NamedThread* _cur_thr;
2842 public:
2843 RememberProcessedThread(JavaThread* jthr) {
2844 Thread* thread = Thread::current();
2845 if (thread->is_Named_thread()) {
2846 _cur_thr = (NamedThread *)thread;
2847 _cur_thr->set_processed_thread(jthr);
2848 } else {
2849 _cur_thr = NULL;
2850 }
2851 }
2852
2853 ~RememberProcessedThread() {
2854 if (_cur_thr) {
2855 _cur_thr->set_processed_thread(NULL);
2856 }
2857 }
2858 };
2859
2860 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2861 // Verify that the deferred card marks have been flushed.
2862 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2863
2864 // Traverse the GCHandles
2865 Thread::oops_do(f, cf);
2866
2867 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2868
2869 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2870 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2871
2872 if (has_last_Java_frame()) {
2873 // Record JavaThread to GC thread
2874 RememberProcessedThread rpt(this);
2875
2876 // Traverse the privileged stack
2877 if (_privileged_stack_top != NULL) {
2878 _privileged_stack_top->oops_do(f);
2879 }
2880
2881 // traverse the registered growable array
2882 if (_array_for_gc != NULL) {
2883 for (int index = 0; index < _array_for_gc->length(); index++) {
2884 f->do_oop(_array_for_gc->adr_at(index));
2885 }
2886 }
2887
2888 // Traverse the monitor chunks
2889 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2890 chunk->oops_do(f);
2891 }
2892
2893 // Traverse the execution stack
2894 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2895 fst.current()->oops_do(f, cf, fst.register_map());
2896 }
2897 }
2898
2899 // callee_target is never live across a gc point so NULL it here should
2900 // it still contain a methdOop.
2901
2902 set_callee_target(NULL);
2903
2904 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2905 // If we have deferred set_locals there might be oops waiting to be
2906 // written
2907 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2908 if (list != NULL) {
2909 for (int i = 0; i < list->length(); i++) {
2910 list->at(i)->oops_do(f);
2911 }
2912 }
2913
2914 // Traverse instance variables at the end since the GC may be moving things
2915 // around using this function
2916 f->do_oop((oop*) &_threadObj);
2917 f->do_oop((oop*) &_vm_result);
2918 f->do_oop((oop*) &_exception_oop);
2919 f->do_oop((oop*) &_pending_async_exception);
2920
2921 if (jvmti_thread_state() != NULL) {
2922 jvmti_thread_state()->oops_do(f);
2923 }
2924 }
2925
2926 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2927 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2928 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2929
2930 if (has_last_Java_frame()) {
2931 // Traverse the execution stack
2932 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2933 fst.current()->nmethods_do(cf);
2934 }
2935 }
2936 }
2937
2938 void JavaThread::metadata_do(void f(Metadata*)) {
2939 if (has_last_Java_frame()) {
2940 // Traverse the execution stack to call f() on the methods in the stack
2941 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2942 fst.current()->metadata_do(f);
2943 }
2944 } else if (is_Compiler_thread()) {
2945 // need to walk ciMetadata in current compile tasks to keep alive.
2946 CompilerThread* ct = (CompilerThread*)this;
2947 if (ct->env() != NULL) {
2948 ct->env()->metadata_do(f);
2949 }
2950 if (ct->task() != NULL) {
2951 ct->task()->metadata_do(f);
2952 }
2953 }
2954 }
2955
2956 // Printing
2957 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2958 switch (_thread_state) {
2959 case _thread_uninitialized: return "_thread_uninitialized";
2960 case _thread_new: return "_thread_new";
2961 case _thread_new_trans: return "_thread_new_trans";
2962 case _thread_in_native: return "_thread_in_native";
2963 case _thread_in_native_trans: return "_thread_in_native_trans";
2964 case _thread_in_vm: return "_thread_in_vm";
2965 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2966 case _thread_in_Java: return "_thread_in_Java";
2967 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2968 case _thread_blocked: return "_thread_blocked";
2969 case _thread_blocked_trans: return "_thread_blocked_trans";
2970 default: return "unknown thread state";
2971 }
2972 }
2973
2974 #ifndef PRODUCT
2975 void JavaThread::print_thread_state_on(outputStream *st) const {
2976 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2977 };
2978 void JavaThread::print_thread_state() const {
2979 print_thread_state_on(tty);
2980 }
2981 #endif // PRODUCT
2982
2983 // Called by Threads::print() for VM_PrintThreads operation
2984 void JavaThread::print_on(outputStream *st) const {
2985 st->print_raw("\"");
2986 st->print_raw(get_thread_name());
2987 st->print_raw("\" ");
2988 oop thread_oop = threadObj();
2989 if (thread_oop != NULL) {
2990 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2991 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2992 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2993 }
2994 Thread::print_on(st);
2995 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2996 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2997 if (thread_oop != NULL) {
2998 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2999 }
3000 #ifndef PRODUCT
3001 print_thread_state_on(st);
3002 _safepoint_state->print_on(st);
3003 #endif // PRODUCT
3004 if (is_Compiler_thread()) {
3005 CompilerThread* ct = (CompilerThread*)this;
3006 if (ct->task() != NULL) {
3007 st->print(" Compiling: ");
3008 ct->task()->print(st, NULL, true, false);
3009 } else {
3010 st->print(" No compile task");
3011 }
3012 st->cr();
3013 }
3014 }
3015
3016 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3017 st->print("%s", get_thread_name_string(buf, buflen));
3018 }
3019
3020 // Called by fatal error handler. The difference between this and
3021 // JavaThread::print() is that we can't grab lock or allocate memory.
3022 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3023 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3024 oop thread_obj = threadObj();
3025 if (thread_obj != NULL) {
3026 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3027 }
3028 st->print(" [");
3029 st->print("%s", _get_thread_state_name(_thread_state));
3030 if (osthread()) {
3031 st->print(", id=%d", osthread()->thread_id());
3032 }
3033 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3034 p2i(stack_end()), p2i(stack_base()));
3035 st->print("]");
3036
3037 if (_threads_hazard_ptr != NULL) {
3038 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3039 }
3040 if (_nested_threads_hazard_ptr != NULL) {
3041 print_nested_threads_hazard_ptrs_on(st);
3042 }
3043 return;
3044 }
3045
3046 // Verification
3047
3048 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3049
3050 void JavaThread::verify() {
3051 // Verify oops in the thread.
3052 oops_do(&VerifyOopClosure::verify_oop, NULL);
3053
3054 // Verify the stack frames.
3055 frames_do(frame_verify);
3056 }
3057
3058 // CR 6300358 (sub-CR 2137150)
3059 // Most callers of this method assume that it can't return NULL but a
3060 // thread may not have a name whilst it is in the process of attaching to
3061 // the VM - see CR 6412693, and there are places where a JavaThread can be
3062 // seen prior to having it's threadObj set (eg JNI attaching threads and
3063 // if vm exit occurs during initialization). These cases can all be accounted
3064 // for such that this method never returns NULL.
3065 const char* JavaThread::get_thread_name() const {
3066 #ifdef ASSERT
3067 // early safepoints can hit while current thread does not yet have TLS
3068 if (!SafepointSynchronize::is_at_safepoint()) {
3069 Thread *cur = Thread::current();
3070 if (!(cur->is_Java_thread() && cur == this)) {
3071 // Current JavaThreads are allowed to get their own name without
3072 // the Threads_lock.
3073 assert_locked_or_safepoint(Threads_lock);
3074 }
3075 }
3076 #endif // ASSERT
3077 return get_thread_name_string();
3078 }
3079
3080 // Returns a non-NULL representation of this thread's name, or a suitable
3081 // descriptive string if there is no set name
3082 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3083 const char* name_str;
3084 oop thread_obj = threadObj();
3085 if (thread_obj != NULL) {
3086 oop name = java_lang_Thread::name(thread_obj);
3087 if (name != NULL) {
3088 if (buf == NULL) {
3089 name_str = java_lang_String::as_utf8_string(name);
3090 } else {
3091 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3092 }
3093 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3094 name_str = "<no-name - thread is attaching>";
3095 } else {
3096 name_str = Thread::name();
3097 }
3098 } else {
3099 name_str = Thread::name();
3100 }
3101 assert(name_str != NULL, "unexpected NULL thread name");
3102 return name_str;
3103 }
3104
3105
3106 const char* JavaThread::get_threadgroup_name() const {
3107 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3108 oop thread_obj = threadObj();
3109 if (thread_obj != NULL) {
3110 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3111 if (thread_group != NULL) {
3112 // ThreadGroup.name can be null
3113 return java_lang_ThreadGroup::name(thread_group);
3114 }
3115 }
3116 return NULL;
3117 }
3118
3119 const char* JavaThread::get_parent_name() const {
3120 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3121 oop thread_obj = threadObj();
3122 if (thread_obj != NULL) {
3123 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3124 if (thread_group != NULL) {
3125 oop parent = java_lang_ThreadGroup::parent(thread_group);
3126 if (parent != NULL) {
3127 // ThreadGroup.name can be null
3128 return java_lang_ThreadGroup::name(parent);
3129 }
3130 }
3131 }
3132 return NULL;
3133 }
3134
3135 ThreadPriority JavaThread::java_priority() const {
3136 oop thr_oop = threadObj();
3137 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3138 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3139 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3140 return priority;
3141 }
3142
3143 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3144
3145 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3146 // Link Java Thread object <-> C++ Thread
3147
3148 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3149 // and put it into a new Handle. The Handle "thread_oop" can then
3150 // be used to pass the C++ thread object to other methods.
3151
3152 // Set the Java level thread object (jthread) field of the
3153 // new thread (a JavaThread *) to C++ thread object using the
3154 // "thread_oop" handle.
3155
3156 // Set the thread field (a JavaThread *) of the
3157 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3158
3159 Handle thread_oop(Thread::current(),
3160 JNIHandles::resolve_non_null(jni_thread));
3161 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3162 "must be initialized");
3163 set_threadObj(thread_oop());
3164 java_lang_Thread::set_thread(thread_oop(), this);
3165
3166 if (prio == NoPriority) {
3167 prio = java_lang_Thread::priority(thread_oop());
3168 assert(prio != NoPriority, "A valid priority should be present");
3169 }
3170
3171 // Push the Java priority down to the native thread; needs Threads_lock
3172 Thread::set_priority(this, prio);
3173
3174 prepare_ext();
3175
3176 // Add the new thread to the Threads list and set it in motion.
3177 // We must have threads lock in order to call Threads::add.
3178 // It is crucial that we do not block before the thread is
3179 // added to the Threads list for if a GC happens, then the java_thread oop
3180 // will not be visited by GC.
3181 Threads::add(this);
3182 }
3183
3184 oop JavaThread::current_park_blocker() {
3185 // Support for JSR-166 locks
3186 oop thread_oop = threadObj();
3187 if (thread_oop != NULL &&
3188 JDK_Version::current().supports_thread_park_blocker()) {
3189 return java_lang_Thread::park_blocker(thread_oop);
3190 }
3191 return NULL;
3192 }
3193
3194
3195 void JavaThread::print_stack_on(outputStream* st) {
3196 if (!has_last_Java_frame()) return;
3197 ResourceMark rm;
3198 HandleMark hm;
3199
3200 RegisterMap reg_map(this);
3201 vframe* start_vf = last_java_vframe(®_map);
3202 int count = 0;
3203 for (vframe* f = start_vf; f; f = f->sender()) {
3204 if (f->is_java_frame()) {
3205 javaVFrame* jvf = javaVFrame::cast(f);
3206 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3207
3208 // Print out lock information
3209 if (JavaMonitorsInStackTrace) {
3210 jvf->print_lock_info_on(st, count);
3211 }
3212 } else {
3213 // Ignore non-Java frames
3214 }
3215
3216 // Bail-out case for too deep stacks
3217 count++;
3218 if (MaxJavaStackTraceDepth == count) return;
3219 }
3220 }
3221
3222
3223 // JVMTI PopFrame support
3224 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3225 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3226 if (in_bytes(size_in_bytes) != 0) {
3227 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3228 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3229 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3230 }
3231 }
3232
3233 void* JavaThread::popframe_preserved_args() {
3234 return _popframe_preserved_args;
3235 }
3236
3237 ByteSize JavaThread::popframe_preserved_args_size() {
3238 return in_ByteSize(_popframe_preserved_args_size);
3239 }
3240
3241 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3242 int sz = in_bytes(popframe_preserved_args_size());
3243 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3244 return in_WordSize(sz / wordSize);
3245 }
3246
3247 void JavaThread::popframe_free_preserved_args() {
3248 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3249 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3250 _popframe_preserved_args = NULL;
3251 _popframe_preserved_args_size = 0;
3252 }
3253
3254 #ifndef PRODUCT
3255
3256 void JavaThread::trace_frames() {
3257 tty->print_cr("[Describe stack]");
3258 int frame_no = 1;
3259 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3260 tty->print(" %d. ", frame_no++);
3261 fst.current()->print_value_on(tty, this);
3262 tty->cr();
3263 }
3264 }
3265
3266 class PrintAndVerifyOopClosure: public OopClosure {
3267 protected:
3268 template <class T> inline void do_oop_work(T* p) {
3269 oop obj = oopDesc::load_decode_heap_oop(p);
3270 if (obj == NULL) return;
3271 tty->print(INTPTR_FORMAT ": ", p2i(p));
3272 if (oopDesc::is_oop_or_null(obj)) {
3273 if (obj->is_objArray()) {
3274 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3275 } else {
3276 obj->print();
3277 }
3278 } else {
3279 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3280 }
3281 tty->cr();
3282 }
3283 public:
3284 virtual void do_oop(oop* p) { do_oop_work(p); }
3285 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3286 };
3287
3288
3289 static void oops_print(frame* f, const RegisterMap *map) {
3290 PrintAndVerifyOopClosure print;
3291 f->print_value();
3292 f->oops_do(&print, NULL, (RegisterMap*)map);
3293 }
3294
3295 // Print our all the locations that contain oops and whether they are
3296 // valid or not. This useful when trying to find the oldest frame
3297 // where an oop has gone bad since the frame walk is from youngest to
3298 // oldest.
3299 void JavaThread::trace_oops() {
3300 tty->print_cr("[Trace oops]");
3301 frames_do(oops_print);
3302 }
3303
3304
3305 #ifdef ASSERT
3306 // Print or validate the layout of stack frames
3307 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3308 ResourceMark rm;
3309 PRESERVE_EXCEPTION_MARK;
3310 FrameValues values;
3311 int frame_no = 0;
3312 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3313 fst.current()->describe(values, ++frame_no);
3314 if (depth == frame_no) break;
3315 }
3316 if (validate_only) {
3317 values.validate();
3318 } else {
3319 tty->print_cr("[Describe stack layout]");
3320 values.print(this);
3321 }
3322 }
3323 #endif
3324
3325 void JavaThread::trace_stack_from(vframe* start_vf) {
3326 ResourceMark rm;
3327 int vframe_no = 1;
3328 for (vframe* f = start_vf; f; f = f->sender()) {
3329 if (f->is_java_frame()) {
3330 javaVFrame::cast(f)->print_activation(vframe_no++);
3331 } else {
3332 f->print();
3333 }
3334 if (vframe_no > StackPrintLimit) {
3335 tty->print_cr("...<more frames>...");
3336 return;
3337 }
3338 }
3339 }
3340
3341
3342 void JavaThread::trace_stack() {
3343 if (!has_last_Java_frame()) return;
3344 ResourceMark rm;
3345 HandleMark hm;
3346 RegisterMap reg_map(this);
3347 trace_stack_from(last_java_vframe(®_map));
3348 }
3349
3350
3351 #endif // PRODUCT
3352
3353
3354 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3355 assert(reg_map != NULL, "a map must be given");
3356 frame f = last_frame();
3357 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3358 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3359 }
3360 return NULL;
3361 }
3362
3363
3364 Klass* JavaThread::security_get_caller_class(int depth) {
3365 vframeStream vfst(this);
3366 vfst.security_get_caller_frame(depth);
3367 if (!vfst.at_end()) {
3368 return vfst.method()->method_holder();
3369 }
3370 return NULL;
3371 }
3372
3373 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3374 assert(thread->is_Compiler_thread(), "must be compiler thread");
3375 CompileBroker::compiler_thread_loop();
3376 }
3377
3378 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3379 NMethodSweeper::sweeper_loop();
3380 }
3381
3382 // Create a CompilerThread
3383 CompilerThread::CompilerThread(CompileQueue* queue,
3384 CompilerCounters* counters)
3385 : JavaThread(&compiler_thread_entry) {
3386 _env = NULL;
3387 _log = NULL;
3388 _task = NULL;
3389 _queue = queue;
3390 _counters = counters;
3391 _buffer_blob = NULL;
3392 _compiler = NULL;
3393
3394 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3395 resource_area()->bias_to(mtCompiler);
3396
3397 #ifndef PRODUCT
3398 _ideal_graph_printer = NULL;
3399 #endif
3400 }
3401
3402 bool CompilerThread::can_call_java() const {
3403 return _compiler != NULL && _compiler->is_jvmci();
3404 }
3405
3406 // Create sweeper thread
3407 CodeCacheSweeperThread::CodeCacheSweeperThread()
3408 : JavaThread(&sweeper_thread_entry) {
3409 _scanned_compiled_method = NULL;
3410 }
3411
3412 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3413 JavaThread::oops_do(f, cf);
3414 if (_scanned_compiled_method != NULL && cf != NULL) {
3415 // Safepoints can occur when the sweeper is scanning an nmethod so
3416 // process it here to make sure it isn't unloaded in the middle of
3417 // a scan.
3418 cf->do_code_blob(_scanned_compiled_method);
3419 }
3420 }
3421
3422 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3423 JavaThread::nmethods_do(cf);
3424 if (_scanned_compiled_method != NULL && cf != NULL) {
3425 // Safepoints can occur when the sweeper is scanning an nmethod so
3426 // process it here to make sure it isn't unloaded in the middle of
3427 // a scan.
3428 cf->do_code_blob(_scanned_compiled_method);
3429 }
3430 }
3431
3432
3433 // ======= Threads ========
3434
3435 // The Threads class links together all active threads, and provides
3436 // operations over all threads. It is protected by the Threads_lock,
3437 // which is also used in other global contexts like safepointing.
3438 // ThreadsListHandles are used to safely perform operations on one
3439 // or more threads without the risk of the thread exiting during the
3440 // operation.
3441 //
3442 // Note: The Threads_lock is currently more widely used than we
3443 // would like. We are actively migrating Threads_lock uses to other
3444 // mechanisms in order to reduce Threads_lock contention.
3445
3446 JavaThread* Threads::_thread_list = NULL;
3447 int Threads::_number_of_threads = 0;
3448 int Threads::_number_of_non_daemon_threads = 0;
3449 int Threads::_return_code = 0;
3450 int Threads::_thread_claim_parity = 0;
3451 size_t JavaThread::_stack_size_at_create = 0;
3452 // Safe Memory Reclamation (SMR) support:
3453 Monitor* Threads::_smr_delete_lock =
3454 new Monitor(Monitor::special, "smr_delete_lock",
3455 false /* allow_vm_block */,
3456 Monitor::_safepoint_check_never);
3457 // The '_cnt', '_max' and '_times" fields are enabled via
3458 // -XX:+EnableThreadSMRStatistics:
3459
3460 // # of parallel threads in _smr_delete_lock->wait().
3461 // Impl note: Hard to imagine > 64K waiting threads so this could be 16-bit,
3462 // but there is no nice 16-bit _FORMAT support.
3463 uint Threads::_smr_delete_lock_wait_cnt = 0;
3464
3465 // Max # of parallel threads in _smr_delete_lock->wait().
3466 // Impl note: See _smr_delete_lock_wait_cnt note.
3467 uint Threads::_smr_delete_lock_wait_max = 0;
3468
3469 // Flag to indicate when an _smr_delete_lock->notify() is needed.
3470 // Impl note: See _smr_delete_lock_wait_cnt note.
3471 volatile uint Threads::_smr_delete_notify = 0;
3472
3473 // # of threads deleted over VM lifetime.
3474 // Impl note: Atomically incremented over VM lifetime so use unsigned for more
3475 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3476 // isn't available everywhere (or is it?).
3477 volatile uint Threads::_smr_deleted_thread_cnt = 0;
3478
3479 // Max time in millis to delete a thread.
3480 // Impl note: 16-bit might be too small on an overloaded machine. Use
3481 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a
3482 // loop for correctness.
3483 volatile uint Threads::_smr_deleted_thread_time_max = 0;
3484
3485 // Cumulative time in millis to delete threads.
3486 // Impl note: Atomically added to over VM lifetime so use unsigned for more
3487 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3488 // isn't available everywhere (or is it?).
3489 volatile uint Threads::_smr_deleted_thread_times = 0;
3490
3491 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0);
3492
3493 // # of ThreadsLists allocated over VM lifetime.
3494 // Impl note: We allocate a new ThreadsList for every thread create and
3495 // every thread delete so we need a bigger type than the
3496 // _smr_deleted_thread_cnt field.
3497 uint64_t Threads::_smr_java_thread_list_alloc_cnt = 1;
3498
3499 // # of ThreadsLists freed over VM lifetime.
3500 // Impl note: See _smr_java_thread_list_alloc_cnt note.
3501 uint64_t Threads::_smr_java_thread_list_free_cnt = 0;
3502
3503 // Max size ThreadsList allocated.
3504 // Impl note: Max # of threads alive at one time should fit in unsigned 32-bit.
3505 uint Threads::_smr_java_thread_list_max = 0;
3506
3507 // Max # of nested ThreadsLists for a thread.
3508 // Impl note: Hard to imagine > 64K nested ThreadsLists so this could be
3509 // 16-bit, but there is no nice 16-bit _FORMAT support.
3510 uint Threads::_smr_nested_thread_list_max = 0;
3511
3512 // # of ThreadsListHandles deleted over VM lifetime.
3513 // Impl note: Atomically incremented over VM lifetime so use unsigned for
3514 // more range. There will be fewer ThreadsListHandles than threads so
3515 // unsigned 32-bit should be fine.
3516 volatile uint Threads::_smr_tlh_cnt = 0;
3517
3518 // Max time in millis to delete a ThreadsListHandle.
3519 // Impl note: 16-bit might be too small on an overloaded machine. Use
3520 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a
3521 // loop for correctness.
3522 volatile uint Threads::_smr_tlh_time_max = 0;
3523
3524 // Cumulative time in millis to delete ThreadsListHandles.
3525 // Impl note: Atomically added to over VM lifetime so use unsigned for more
3526 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3527 // isn't available everywhere (or is it?).
3528 volatile uint Threads::_smr_tlh_times = 0;
3529
3530 ThreadsList* Threads::_smr_to_delete_list = NULL;
3531
3532 // # of parallel ThreadsLists on the to-delete list.
3533 // Impl note: Hard to imagine > 64K ThreadsLists needing to be deleted so
3534 // this could be 16-bit, but there is no nice 16-bit _FORMAT support.
3535 uint Threads::_smr_to_delete_list_cnt = 0;
3536
3537 // Max # of parallel ThreadsLists on the to-delete list.
3538 // Impl note: See _smr_to_delete_list_cnt note.
3539 uint Threads::_smr_to_delete_list_max = 0;
3540
3541 #ifdef ASSERT
3542 bool Threads::_vm_complete = false;
3543 #endif
3544
3545 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3546 Prefetch::read((void*)addr, prefetch_interval);
3547 return *addr;
3548 }
3549
3550 // Possibly the ugliest for loop the world has seen. C++ does not allow
3551 // multiple types in the declaration section of the for loop. In this case
3552 // we are only dealing with pointers and hence can cast them. It looks ugly
3553 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3554 #define DO_JAVA_THREADS(LIST, X) \
3555 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3556 *MACRO_list = (JavaThread*)(LIST), \
3557 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3558 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3559 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3560 MACRO_current_p != MACRO_end; \
3561 MACRO_current_p++, \
3562 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3563
3564 inline ThreadsList* Threads::get_smr_java_thread_list() {
3565 return (ThreadsList*)OrderAccess::load_acquire(&_smr_java_thread_list);
3566 }
3567
3568 // All JavaThreads
3569 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X)
3570
3571 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3572 void Threads::threads_do(ThreadClosure* tc) {
3573 assert_locked_or_safepoint(Threads_lock);
3574 // ALL_JAVA_THREADS iterates through all JavaThreads
3575 ALL_JAVA_THREADS(p) {
3576 tc->do_thread(p);
3577 }
3578 // Someday we could have a table or list of all non-JavaThreads.
3579 // For now, just manually iterate through them.
3580 tc->do_thread(VMThread::vm_thread());
3581 Universe::heap()->gc_threads_do(tc);
3582 WatcherThread *wt = WatcherThread::watcher_thread();
3583 // Strictly speaking, the following NULL check isn't sufficient to make sure
3584 // the data for WatcherThread is still valid upon being examined. However,
3585 // considering that WatchThread terminates when the VM is on the way to
3586 // exit at safepoint, the chance of the above is extremely small. The right
3587 // way to prevent termination of WatcherThread would be to acquire
3588 // Terminator_lock, but we can't do that without violating the lock rank
3589 // checking in some cases.
3590 if (wt != NULL) {
3591 tc->do_thread(wt);
3592 }
3593
3594 // If CompilerThreads ever become non-JavaThreads, add them here
3595 }
3596
3597 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3598 int cp = Threads::thread_claim_parity();
3599 ALL_JAVA_THREADS(p) {
3600 if (p->claim_oops_do(is_par, cp)) {
3601 tc->do_thread(p);
3602 }
3603 }
3604 VMThread* vmt = VMThread::vm_thread();
3605 if (vmt->claim_oops_do(is_par, cp)) {
3606 tc->do_thread(vmt);
3607 }
3608 }
3609
3610 // The system initialization in the library has three phases.
3611 //
3612 // Phase 1: java.lang.System class initialization
3613 // java.lang.System is a primordial class loaded and initialized
3614 // by the VM early during startup. java.lang.System.<clinit>
3615 // only does registerNatives and keeps the rest of the class
3616 // initialization work later until thread initialization completes.
3617 //
3618 // System.initPhase1 initializes the system properties, the static
3619 // fields in, out, and err. Set up java signal handlers, OS-specific
3620 // system settings, and thread group of the main thread.
3621 static void call_initPhase1(TRAPS) {
3622 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3623 JavaValue result(T_VOID);
3624 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3625 vmSymbols::void_method_signature(), CHECK);
3626 }
3627
3628 // Phase 2. Module system initialization
3629 // This will initialize the module system. Only java.base classes
3630 // can be loaded until phase 2 completes.
3631 //
3632 // Call System.initPhase2 after the compiler initialization and jsr292
3633 // classes get initialized because module initialization runs a lot of java
3634 // code, that for performance reasons, should be compiled. Also, this will
3635 // enable the startup code to use lambda and other language features in this
3636 // phase and onward.
3637 //
3638 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3639 static void call_initPhase2(TRAPS) {
3640 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3641
3642 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3643
3644 JavaValue result(T_INT);
3645 JavaCallArguments args;
3646 args.push_int(DisplayVMOutputToStderr);
3647 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3648 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3649 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3650 if (result.get_jint() != JNI_OK) {
3651 vm_exit_during_initialization(); // no message or exception
3652 }
3653
3654 universe_post_module_init();
3655 }
3656
3657 // Phase 3. final setup - set security manager, system class loader and TCCL
3658 //
3659 // This will instantiate and set the security manager, set the system class
3660 // loader as well as the thread context class loader. The security manager
3661 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3662 // other modules or the application's classpath.
3663 static void call_initPhase3(TRAPS) {
3664 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3665 JavaValue result(T_VOID);
3666 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3667 vmSymbols::void_method_signature(), CHECK);
3668 }
3669
3670 // Safe Memory Reclamation (SMR) support:
3671 //
3672
3673 // Acquire a stable ThreadsList.
3674 //
3675 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) {
3676 assert(self != NULL, "sanity check");
3677 // acquire_stable_list_nested_path() will grab the Threads_lock
3678 // so let's make sure the ThreadsListHandle is in a safe place.
3679 // ThreadsListSetter cannot make this check on this code path.
3680 debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3681
3682 if (self->get_threads_hazard_ptr() == NULL) {
3683 // The typical case is first.
3684 return acquire_stable_list_fast_path(self);
3685 }
3686
3687 // The nested case is rare.
3688 return acquire_stable_list_nested_path(self);
3689 }
3690
3691 // Fast path (and lock free) way to acquire a stable ThreadsList.
3692 //
3693 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) {
3694 assert(self != NULL, "sanity check");
3695 assert(self->get_threads_hazard_ptr() == NULL, "sanity check");
3696 assert(self->get_nested_threads_hazard_ptr() == NULL,
3697 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
3698
3699 ThreadsList* threads;
3700
3701 // Stable recording of a hazard ptr for SMR. This code does not use
3702 // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr
3703 // fields is racy relative to code that uses those fields with locks.
3704 // OrderAccess and Atomic functions are used to deal with those races.
3705 //
3706 while (true) {
3707 threads = get_smr_java_thread_list();
3708
3709 // Publish a tagged hazard ptr to denote that the hazard ptr is not
3710 // yet verified as being stable. Due to the fence after the hazard
3711 // ptr write, it will be sequentially consistent w.r.t. the
3712 // sequentially consistent writes of the ThreadsList, even on
3713 // non-multiple copy atomic machines where stores can be observed
3714 // in different order from different observer threads.
3715 ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads);
3716 self->set_threads_hazard_ptr(unverified_threads);
3717
3718 // If _smr_java_thread_list has changed, we have lost a race with
3719 // Threads::add() or Threads::remove() and have to try again.
3720 if (get_smr_java_thread_list() != threads) {
3721 continue;
3722 }
3723
3724 // We try to remove the tag which will verify the hazard ptr as
3725 // being stable. This exchange can race with a scanning thread
3726 // which might invalidate the tagged hazard ptr to keep it from
3727 // being followed to access JavaThread ptrs. If we lose the race,
3728 // we simply retry. If we win the race, then the stable hazard
3729 // ptr is officially published.
3730 if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) {
3731 break;
3732 }
3733 }
3734
3735 // A stable hazard ptr has been published letting other threads know
3736 // that the ThreadsList and the JavaThreads reachable from this list
3737 // are protected and hence they should not be deleted until everyone
3738 // agrees it is safe to do so.
3739
3740 return threads;
3741 }
3742
3743 // Acquire a nested stable ThreadsList; this is rare so it uses
3744 // Threads_lock.
3745 //
3746 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) {
3747 assert(self != NULL, "sanity check");
3748 assert(self->get_threads_hazard_ptr() != NULL,
3749 "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr");
3750
3751 // The thread already has a hazard ptr (ThreadsList ref) so we need
3752 // to create a nested ThreadsListHandle with the current ThreadsList
3753 // since it might be different than our current hazard ptr. The need
3754 // for a nested ThreadsListHandle is rare so we do this while holding
3755 // the Threads_lock so we don't race with the scanning code; the code
3756 // is so much simpler this way.
3757
3758 NestedThreadsList* node;
3759 {
3760 // Only grab the Threads_lock if we don't already own it.
3761 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3762 node = new NestedThreadsList(get_smr_java_thread_list());
3763 // We insert at the front of the list to match up with the delete
3764 // in release_stable_list().
3765 node->set_next(self->get_nested_threads_hazard_ptr());
3766 self->set_nested_threads_hazard_ptr(node);
3767 if (EnableThreadSMRStatistics) {
3768 self->inc_nested_threads_hazard_ptr_cnt();
3769 if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) {
3770 _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt();
3771 }
3772 }
3773 }
3774 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::acquire_stable_list: add NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list()));
3775
3776 return node->t_list();
3777 }
3778
3779 inline void Threads::add_smr_deleted_thread_times(uint add_value) {
3780 Atomic::add(add_value, &_smr_deleted_thread_times);
3781 }
3782
3783 inline void Threads::inc_smr_deleted_thread_cnt() {
3784 Atomic::inc(&_smr_deleted_thread_cnt);
3785 }
3786
3787 // Release a stable ThreadsList.
3788 //
3789 void Threads::release_stable_list(Thread *self) {
3790 assert(self != NULL, "sanity check");
3791 // release_stable_list_nested_path() will grab the Threads_lock
3792 // so let's make sure the ThreadsListHandle is in a safe place.
3793 debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3794
3795 if (self->get_nested_threads_hazard_ptr() == NULL) {
3796 // The typical case is first.
3797 release_stable_list_fast_path(self);
3798 return;
3799 }
3800
3801 // The nested case is rare.
3802 release_stable_list_nested_path(self);
3803 }
3804
3805 // Fast path way to release a stable ThreadsList. The release portion
3806 // is lock-free, but the wake up portion is not.
3807 //
3808 void Threads::release_stable_list_fast_path(Thread *self) {
3809 assert(self != NULL, "sanity check");
3810 assert(self->get_threads_hazard_ptr() != NULL, "sanity check");
3811 assert(self->get_nested_threads_hazard_ptr() == NULL,
3812 "cannot have a nested hazard ptr when releasing a regular hazard ptr");
3813
3814 // After releasing the hazard ptr, other threads may go ahead and
3815 // free up some memory temporarily used by a ThreadsList snapshot.
3816 self->set_threads_hazard_ptr(NULL);
3817
3818 // We use double-check locking to reduce traffic on the system
3819 // wide smr_delete_lock.
3820 if (Threads::smr_delete_notify()) {
3821 // An exiting thread might be waiting in smr_delete(); we need to
3822 // check with smr_delete_lock to be sure.
3823 release_stable_list_wake_up((char *) "regular hazard ptr");
3824 }
3825 }
3826
3827 // Release a nested stable ThreadsList; this is rare so it uses
3828 // Threads_lock.
3829 //
3830 void Threads::release_stable_list_nested_path(Thread *self) {
3831 assert(self != NULL, "sanity check");
3832 assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check");
3833 assert(self->get_threads_hazard_ptr() != NULL,
3834 "must have a regular hazard ptr to have nested hazard ptrs");
3835
3836 // We have a nested ThreadsListHandle so we have to release it first.
3837 // The need for a nested ThreadsListHandle is rare so we do this while
3838 // holding the Threads_lock so we don't race with the scanning code;
3839 // the code is so much simpler this way.
3840
3841 NestedThreadsList *node;
3842 {
3843 // Only grab the Threads_lock if we don't already own it.
3844 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3845 // We remove from the front of the list to match up with the insert
3846 // in acquire_stable_list().
3847 node = self->get_nested_threads_hazard_ptr();
3848 self->set_nested_threads_hazard_ptr(node->next());
3849 if (EnableThreadSMRStatistics) {
3850 self->dec_nested_threads_hazard_ptr_cnt();
3851 }
3852 }
3853
3854 // An exiting thread might be waiting in smr_delete(); we need to
3855 // check with smr_delete_lock to be sure.
3856 release_stable_list_wake_up((char *) "nested hazard ptr");
3857
3858 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list: delete NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list()));
3859
3860 delete node;
3861 }
3862
3863 // Wake up portion of the release stable ThreadsList protocol;
3864 // uses the smr_delete_lock().
3865 //
3866 void Threads::release_stable_list_wake_up(char *log_str) {
3867 assert(log_str != NULL, "sanity check");
3868
3869 // Note: smr_delete_lock is held in smr_delete() for the entire
3870 // hazard ptr search so that we do not lose this notify() if
3871 // the exiting thread has to wait. That code path also holds
3872 // Threads_lock (which was grabbed before smr_delete_lock) so that
3873 // threads_do() can be called. This means the system can't start a
3874 // safepoint which means this thread can't take too long to get to
3875 // a safepoint because of being blocked on smr_delete_lock.
3876 //
3877 MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag);
3878 if (Threads::smr_delete_notify()) {
3879 // Notify any exiting JavaThreads that are waiting in smr_delete()
3880 // that we've released a ThreadsList.
3881 ml.notify_all();
3882 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str);
3883 }
3884 }
3885
3886 inline void Threads::update_smr_deleted_thread_time_max(uint new_value) {
3887 while (true) {
3888 uint cur_value = _smr_deleted_thread_time_max;
3889 if (new_value <= cur_value) {
3890 // No need to update max value so we're done.
3891 break;
3892 }
3893 if (Atomic::cmpxchg(new_value, &_smr_deleted_thread_time_max, cur_value) == cur_value) {
3894 // Updated max value so we're done. Otherwise try it all again.
3895 break;
3896 }
3897 }
3898 }
3899
3900 inline ThreadsList* Threads::xchg_smr_java_thread_list(ThreadsList* new_list) {
3901 return (ThreadsList*)Atomic::xchg(new_list, &_smr_java_thread_list);
3902 }
3903
3904 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3905 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3906
3907 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3908 create_vm_init_libraries();
3909 }
3910
3911 initialize_class(vmSymbols::java_lang_String(), CHECK);
3912
3913 // Inject CompactStrings value after the static initializers for String ran.
3914 java_lang_String::set_compact_strings(CompactStrings);
3915
3916 // Initialize java_lang.System (needed before creating the thread)
3917 initialize_class(vmSymbols::java_lang_System(), CHECK);
3918 // The VM creates & returns objects of this class. Make sure it's initialized.
3919 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3920 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3921 Handle thread_group = create_initial_thread_group(CHECK);
3922 Universe::set_main_thread_group(thread_group());
3923 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3924 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3925 main_thread->set_threadObj(thread_object);
3926 // Set thread status to running since main thread has
3927 // been started and running.
3928 java_lang_Thread::set_thread_status(thread_object,
3929 java_lang_Thread::RUNNABLE);
3930
3931 // The VM creates objects of this class.
3932 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3933
3934 // The VM preresolves methods to these classes. Make sure that they get initialized
3935 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3936 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3937
3938 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3939 call_initPhase1(CHECK);
3940
3941 // get the Java runtime name after java.lang.System is initialized
3942 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3943 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3944
3945 // an instance of OutOfMemory exception has been allocated earlier
3946 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3947 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3948 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3949 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3950 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3951 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3952 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3953 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3954 }
3955
3956 void Threads::initialize_jsr292_core_classes(TRAPS) {
3957 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3958
3959 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3960 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3961 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3962 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3963 }
3964
3965 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3966 extern void JDK_Version_init();
3967
3968 // Preinitialize version info.
3969 VM_Version::early_initialize();
3970
3971 // Check version
3972 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3973
3974 // Initialize library-based TLS
3975 ThreadLocalStorage::init();
3976
3977 // Initialize the output stream module
3978 ostream_init();
3979
3980 // Process java launcher properties.
3981 Arguments::process_sun_java_launcher_properties(args);
3982
3983 // Initialize the os module
3984 os::init();
3985
3986 // Record VM creation timing statistics
3987 TraceVmCreationTime create_vm_timer;
3988 create_vm_timer.start();
3989
3990 // Initialize system properties.
3991 Arguments::init_system_properties();
3992
3993 // So that JDK version can be used as a discriminator when parsing arguments
3994 JDK_Version_init();
3995
3996 // Update/Initialize System properties after JDK version number is known
3997 Arguments::init_version_specific_system_properties();
3998
3999 // Make sure to initialize log configuration *before* parsing arguments
4000 LogConfiguration::initialize(create_vm_timer.begin_time());
4001
4002 // Parse arguments
4003 // Note: this internally calls os::init_container_support()
4004 jint parse_result = Arguments::parse(args);
4005 if (parse_result != JNI_OK) return parse_result;
4006
4007 os::init_before_ergo();
4008
4009 jint ergo_result = Arguments::apply_ergo();
4010 if (ergo_result != JNI_OK) return ergo_result;
4011
4012 // Final check of all ranges after ergonomics which may change values.
4013 if (!CommandLineFlagRangeList::check_ranges()) {
4014 return JNI_EINVAL;
4015 }
4016
4017 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
4018 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
4019 if (!constraint_result) {
4020 return JNI_EINVAL;
4021 }
4022
4023 CommandLineFlagWriteableList::mark_startup();
4024
4025 if (PauseAtStartup) {
4026 os::pause();
4027 }
4028
4029 HOTSPOT_VM_INIT_BEGIN();
4030
4031 // Timing (must come after argument parsing)
4032 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
4033
4034 // Initialize the os module after parsing the args
4035 jint os_init_2_result = os::init_2();
4036 if (os_init_2_result != JNI_OK) return os_init_2_result;
4037
4038 SafepointMechanism::initialize();
4039
4040 jint adjust_after_os_result = Arguments::adjust_after_os();
4041 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
4042
4043 // Initialize output stream logging
4044 ostream_init_log();
4045
4046 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
4047 // Must be before create_vm_init_agents()
4048 if (Arguments::init_libraries_at_startup()) {
4049 convert_vm_init_libraries_to_agents();
4050 }
4051
4052 // Launch -agentlib/-agentpath and converted -Xrun agents
4053 if (Arguments::init_agents_at_startup()) {
4054 create_vm_init_agents();
4055 }
4056
4057 // Initialize Threads state
4058 _thread_list = NULL;
4059 _number_of_threads = 0;
4060 _number_of_non_daemon_threads = 0;
4061
4062 // Initialize global data structures and create system classes in heap
4063 vm_init_globals();
4064
4065 #if INCLUDE_JVMCI
4066 if (JVMCICounterSize > 0) {
4067 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
4068 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
4069 } else {
4070 JavaThread::_jvmci_old_thread_counters = NULL;
4071 }
4072 #endif // INCLUDE_JVMCI
4073
4074 // Attach the main thread to this os thread
4075 JavaThread* main_thread = new JavaThread();
4076 main_thread->set_thread_state(_thread_in_vm);
4077 main_thread->initialize_thread_current();
4078 // must do this before set_active_handles
4079 main_thread->record_stack_base_and_size();
4080 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
4081
4082 if (!main_thread->set_as_starting_thread()) {
4083 vm_shutdown_during_initialization(
4084 "Failed necessary internal allocation. Out of swap space");
4085 main_thread->smr_delete();
4086 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4087 return JNI_ENOMEM;
4088 }
4089
4090 // Enable guard page *after* os::create_main_thread(), otherwise it would
4091 // crash Linux VM, see notes in os_linux.cpp.
4092 main_thread->create_stack_guard_pages();
4093
4094 // Initialize Java-Level synchronization subsystem
4095 ObjectMonitor::Initialize();
4096
4097 // Initialize global modules
4098 jint status = init_globals();
4099 if (status != JNI_OK) {
4100 main_thread->smr_delete();
4101 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4102 return status;
4103 }
4104
4105 if (TRACE_INITIALIZE() != JNI_OK) {
4106 vm_exit_during_initialization("Failed to initialize tracing backend");
4107 }
4108
4109 // Should be done after the heap is fully created
4110 main_thread->cache_global_variables();
4111
4112 HandleMark hm;
4113
4114 { MutexLocker mu(Threads_lock);
4115 Threads::add(main_thread);
4116 }
4117
4118 // Any JVMTI raw monitors entered in onload will transition into
4119 // real raw monitor. VM is setup enough here for raw monitor enter.
4120 JvmtiExport::transition_pending_onload_raw_monitors();
4121
4122 // Create the VMThread
4123 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
4124
4125 VMThread::create();
4126 Thread* vmthread = VMThread::vm_thread();
4127
4128 if (!os::create_thread(vmthread, os::vm_thread)) {
4129 vm_exit_during_initialization("Cannot create VM thread. "
4130 "Out of system resources.");
4131 }
4132
4133 // Wait for the VM thread to become ready, and VMThread::run to initialize
4134 // Monitors can have spurious returns, must always check another state flag
4135 {
4136 MutexLocker ml(Notify_lock);
4137 os::start_thread(vmthread);
4138 while (vmthread->active_handles() == NULL) {
4139 Notify_lock->wait();
4140 }
4141 }
4142 }
4143
4144 assert(Universe::is_fully_initialized(), "not initialized");
4145 if (VerifyDuringStartup) {
4146 // Make sure we're starting with a clean slate.
4147 VM_Verify verify_op;
4148 VMThread::execute(&verify_op);
4149 }
4150
4151 Thread* THREAD = Thread::current();
4152
4153 // Always call even when there are not JVMTI environments yet, since environments
4154 // may be attached late and JVMTI must track phases of VM execution
4155 JvmtiExport::enter_early_start_phase();
4156
4157 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4158 JvmtiExport::post_early_vm_start();
4159
4160 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
4161
4162 // We need this for ClassDataSharing - the initial vm.info property is set
4163 // with the default value of CDS "sharing" which may be reset through
4164 // command line options.
4165 reset_vm_info_property(CHECK_JNI_ERR);
4166
4167 quicken_jni_functions();
4168
4169 // No more stub generation allowed after that point.
4170 StubCodeDesc::freeze();
4171
4172 // Set flag that basic initialization has completed. Used by exceptions and various
4173 // debug stuff, that does not work until all basic classes have been initialized.
4174 set_init_completed();
4175
4176 LogConfiguration::post_initialize();
4177 Metaspace::post_initialize();
4178
4179 HOTSPOT_VM_INIT_END();
4180
4181 // record VM initialization completion time
4182 #if INCLUDE_MANAGEMENT
4183 Management::record_vm_init_completed();
4184 #endif // INCLUDE_MANAGEMENT
4185
4186 // Signal Dispatcher needs to be started before VMInit event is posted
4187 os::signal_init(CHECK_JNI_ERR);
4188
4189 // Start Attach Listener if +StartAttachListener or it can't be started lazily
4190 if (!DisableAttachMechanism) {
4191 AttachListener::vm_start();
4192 if (StartAttachListener || AttachListener::init_at_startup()) {
4193 AttachListener::init();
4194 }
4195 }
4196
4197 // Launch -Xrun agents
4198 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4199 // back-end can launch with -Xdebug -Xrunjdwp.
4200 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4201 create_vm_init_libraries();
4202 }
4203
4204 if (CleanChunkPoolAsync) {
4205 Chunk::start_chunk_pool_cleaner_task();
4206 }
4207
4208 // initialize compiler(s)
4209 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4210 CompileBroker::compilation_init(CHECK_JNI_ERR);
4211 #endif
4212
4213 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4214 // It is done after compilers are initialized, because otherwise compilations of
4215 // signature polymorphic MH intrinsics can be missed
4216 // (see SystemDictionary::find_method_handle_intrinsic).
4217 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4218
4219 // This will initialize the module system. Only java.base classes can be
4220 // loaded until phase 2 completes
4221 call_initPhase2(CHECK_JNI_ERR);
4222
4223 // Always call even when there are not JVMTI environments yet, since environments
4224 // may be attached late and JVMTI must track phases of VM execution
4225 JvmtiExport::enter_start_phase();
4226
4227 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4228 JvmtiExport::post_vm_start();
4229
4230 // Final system initialization including security manager and system class loader
4231 call_initPhase3(CHECK_JNI_ERR);
4232
4233 // cache the system and platform class loaders
4234 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4235
4236 #if INCLUDE_JVMCI
4237 if (EnableJVMCI) {
4238 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
4239 // The JVMCI Java initialization code will read this flag and
4240 // do the printing if it's set.
4241 bool init = JVMCIPrintProperties;
4242
4243 if (!init) {
4244 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4245 // compilations via JVMCI will not actually block until JVMCI is initialized.
4246 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4247 }
4248
4249 if (init) {
4250 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
4251 }
4252 }
4253 #endif
4254
4255 // Always call even when there are not JVMTI environments yet, since environments
4256 // may be attached late and JVMTI must track phases of VM execution
4257 JvmtiExport::enter_live_phase();
4258
4259 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4260 JvmtiExport::post_vm_initialized();
4261
4262 if (TRACE_START() != JNI_OK) {
4263 vm_exit_during_initialization("Failed to start tracing backend.");
4264 }
4265
4266 #if INCLUDE_MANAGEMENT
4267 Management::initialize(THREAD);
4268
4269 if (HAS_PENDING_EXCEPTION) {
4270 // management agent fails to start possibly due to
4271 // configuration problem and is responsible for printing
4272 // stack trace if appropriate. Simply exit VM.
4273 vm_exit(1);
4274 }
4275 #endif // INCLUDE_MANAGEMENT
4276
4277 if (MemProfiling) MemProfiler::engage();
4278 StatSampler::engage();
4279 if (CheckJNICalls) JniPeriodicChecker::engage();
4280
4281 BiasedLocking::init();
4282
4283 #if INCLUDE_RTM_OPT
4284 RTMLockingCounters::init();
4285 #endif
4286
4287 if (JDK_Version::current().post_vm_init_hook_enabled()) {
4288 call_postVMInitHook(THREAD);
4289 // The Java side of PostVMInitHook.run must deal with all
4290 // exceptions and provide means of diagnosis.
4291 if (HAS_PENDING_EXCEPTION) {
4292 CLEAR_PENDING_EXCEPTION;
4293 }
4294 }
4295
4296 {
4297 MutexLocker ml(PeriodicTask_lock);
4298 // Make sure the WatcherThread can be started by WatcherThread::start()
4299 // or by dynamic enrollment.
4300 WatcherThread::make_startable();
4301 // Start up the WatcherThread if there are any periodic tasks
4302 // NOTE: All PeriodicTasks should be registered by now. If they
4303 // aren't, late joiners might appear to start slowly (we might
4304 // take a while to process their first tick).
4305 if (PeriodicTask::num_tasks() > 0) {
4306 WatcherThread::start();
4307 }
4308 }
4309
4310 create_vm_timer.end();
4311 #ifdef ASSERT
4312 _vm_complete = true;
4313 #endif
4314
4315 if (DumpSharedSpaces) {
4316 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4317 ShouldNotReachHere();
4318 }
4319
4320 return JNI_OK;
4321 }
4322
4323 // type for the Agent_OnLoad and JVM_OnLoad entry points
4324 extern "C" {
4325 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4326 }
4327 // Find a command line agent library and return its entry point for
4328 // -agentlib: -agentpath: -Xrun
4329 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4330 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4331 const char *on_load_symbols[],
4332 size_t num_symbol_entries) {
4333 OnLoadEntry_t on_load_entry = NULL;
4334 void *library = NULL;
4335
4336 if (!agent->valid()) {
4337 char buffer[JVM_MAXPATHLEN];
4338 char ebuf[1024] = "";
4339 const char *name = agent->name();
4340 const char *msg = "Could not find agent library ";
4341
4342 // First check to see if agent is statically linked into executable
4343 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4344 library = agent->os_lib();
4345 } else if (agent->is_absolute_path()) {
4346 library = os::dll_load(name, ebuf, sizeof ebuf);
4347 if (library == NULL) {
4348 const char *sub_msg = " in absolute path, with error: ";
4349 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4350 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4351 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4352 // If we can't find the agent, exit.
4353 vm_exit_during_initialization(buf, NULL);
4354 FREE_C_HEAP_ARRAY(char, buf);
4355 }
4356 } else {
4357 // Try to load the agent from the standard dll directory
4358 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4359 name)) {
4360 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4361 }
4362 if (library == NULL) { // Try the library path directory.
4363 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4364 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4365 }
4366 if (library == NULL) {
4367 const char *sub_msg = " on the library path, with error: ";
4368 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4369 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4370 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4371 // If we can't find the agent, exit.
4372 vm_exit_during_initialization(buf, NULL);
4373 FREE_C_HEAP_ARRAY(char, buf);
4374 }
4375 }
4376 }
4377 agent->set_os_lib(library);
4378 agent->set_valid();
4379 }
4380
4381 // Find the OnLoad function.
4382 on_load_entry =
4383 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4384 false,
4385 on_load_symbols,
4386 num_symbol_entries));
4387 return on_load_entry;
4388 }
4389
4390 // Find the JVM_OnLoad entry point
4391 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4392 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4393 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4394 }
4395
4396 // Find the Agent_OnLoad entry point
4397 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4398 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4399 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4400 }
4401
4402 // For backwards compatibility with -Xrun
4403 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4404 // treated like -agentpath:
4405 // Must be called before agent libraries are created
4406 void Threads::convert_vm_init_libraries_to_agents() {
4407 AgentLibrary* agent;
4408 AgentLibrary* next;
4409
4410 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4411 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4412 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4413
4414 // If there is an JVM_OnLoad function it will get called later,
4415 // otherwise see if there is an Agent_OnLoad
4416 if (on_load_entry == NULL) {
4417 on_load_entry = lookup_agent_on_load(agent);
4418 if (on_load_entry != NULL) {
4419 // switch it to the agent list -- so that Agent_OnLoad will be called,
4420 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4421 Arguments::convert_library_to_agent(agent);
4422 } else {
4423 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4424 }
4425 }
4426 }
4427 }
4428
4429 // Create agents for -agentlib: -agentpath: and converted -Xrun
4430 // Invokes Agent_OnLoad
4431 // Called very early -- before JavaThreads exist
4432 void Threads::create_vm_init_agents() {
4433 extern struct JavaVM_ main_vm;
4434 AgentLibrary* agent;
4435
4436 JvmtiExport::enter_onload_phase();
4437
4438 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4439 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4440
4441 if (on_load_entry != NULL) {
4442 // Invoke the Agent_OnLoad function
4443 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4444 if (err != JNI_OK) {
4445 vm_exit_during_initialization("agent library failed to init", agent->name());
4446 }
4447 } else {
4448 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4449 }
4450 }
4451 JvmtiExport::enter_primordial_phase();
4452 }
4453
4454 extern "C" {
4455 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4456 }
4457
4458 void Threads::shutdown_vm_agents() {
4459 // Send any Agent_OnUnload notifications
4460 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4461 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4462 extern struct JavaVM_ main_vm;
4463 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4464
4465 // Find the Agent_OnUnload function.
4466 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4467 os::find_agent_function(agent,
4468 false,
4469 on_unload_symbols,
4470 num_symbol_entries));
4471
4472 // Invoke the Agent_OnUnload function
4473 if (unload_entry != NULL) {
4474 JavaThread* thread = JavaThread::current();
4475 ThreadToNativeFromVM ttn(thread);
4476 HandleMark hm(thread);
4477 (*unload_entry)(&main_vm);
4478 }
4479 }
4480 }
4481
4482 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4483 // Invokes JVM_OnLoad
4484 void Threads::create_vm_init_libraries() {
4485 extern struct JavaVM_ main_vm;
4486 AgentLibrary* agent;
4487
4488 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4489 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4490
4491 if (on_load_entry != NULL) {
4492 // Invoke the JVM_OnLoad function
4493 JavaThread* thread = JavaThread::current();
4494 ThreadToNativeFromVM ttn(thread);
4495 HandleMark hm(thread);
4496 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4497 if (err != JNI_OK) {
4498 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4499 }
4500 } else {
4501 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4502 }
4503 }
4504 }
4505
4506
4507 // Last thread running calls java.lang.Shutdown.shutdown()
4508 void JavaThread::invoke_shutdown_hooks() {
4509 HandleMark hm(this);
4510
4511 // We could get here with a pending exception, if so clear it now.
4512 if (this->has_pending_exception()) {
4513 this->clear_pending_exception();
4514 }
4515
4516 EXCEPTION_MARK;
4517 Klass* shutdown_klass =
4518 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4519 THREAD);
4520 if (shutdown_klass != NULL) {
4521 // SystemDictionary::resolve_or_null will return null if there was
4522 // an exception. If we cannot load the Shutdown class, just don't
4523 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4524 // and finalizers (if runFinalizersOnExit is set) won't be run.
4525 // Note that if a shutdown hook was registered or runFinalizersOnExit
4526 // was called, the Shutdown class would have already been loaded
4527 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4528 JavaValue result(T_VOID);
4529 JavaCalls::call_static(&result,
4530 shutdown_klass,
4531 vmSymbols::shutdown_method_name(),
4532 vmSymbols::void_method_signature(),
4533 THREAD);
4534 }
4535 CLEAR_PENDING_EXCEPTION;
4536 }
4537
4538 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4539 // the program falls off the end of main(). Another VM exit path is through
4540 // vm_exit() when the program calls System.exit() to return a value or when
4541 // there is a serious error in VM. The two shutdown paths are not exactly
4542 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4543 // and VM_Exit op at VM level.
4544 //
4545 // Shutdown sequence:
4546 // + Shutdown native memory tracking if it is on
4547 // + Wait until we are the last non-daemon thread to execute
4548 // <-- every thing is still working at this moment -->
4549 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4550 // shutdown hooks, run finalizers if finalization-on-exit
4551 // + Call before_exit(), prepare for VM exit
4552 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4553 // currently the only user of this mechanism is File.deleteOnExit())
4554 // > stop StatSampler, watcher thread, CMS threads,
4555 // post thread end and vm death events to JVMTI,
4556 // stop signal thread
4557 // + Call JavaThread::exit(), it will:
4558 // > release JNI handle blocks, remove stack guard pages
4559 // > remove this thread from Threads list
4560 // <-- no more Java code from this thread after this point -->
4561 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4562 // the compiler threads at safepoint
4563 // <-- do not use anything that could get blocked by Safepoint -->
4564 // + Disable tracing at JNI/JVM barriers
4565 // + Set _vm_exited flag for threads that are still running native code
4566 // + Delete this thread
4567 // + Call exit_globals()
4568 // > deletes tty
4569 // > deletes PerfMemory resources
4570 // + Return to caller
4571
4572 bool Threads::destroy_vm() {
4573 JavaThread* thread = JavaThread::current();
4574
4575 #ifdef ASSERT
4576 _vm_complete = false;
4577 #endif
4578 // Wait until we are the last non-daemon thread to execute
4579 { MutexLocker nu(Threads_lock);
4580 while (Threads::number_of_non_daemon_threads() > 1)
4581 // This wait should make safepoint checks, wait without a timeout,
4582 // and wait as a suspend-equivalent condition.
4583 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4584 Mutex::_as_suspend_equivalent_flag);
4585 }
4586
4587 // Hang forever on exit if we are reporting an error.
4588 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4589 os::infinite_sleep();
4590 }
4591 os::wait_for_keypress_at_exit();
4592
4593 // run Java level shutdown hooks
4594 thread->invoke_shutdown_hooks();
4595
4596 before_exit(thread);
4597
4598 thread->exit(true);
4599
4600 // Stop VM thread.
4601 {
4602 // 4945125 The vm thread comes to a safepoint during exit.
4603 // GC vm_operations can get caught at the safepoint, and the
4604 // heap is unparseable if they are caught. Grab the Heap_lock
4605 // to prevent this. The GC vm_operations will not be able to
4606 // queue until after the vm thread is dead. After this point,
4607 // we'll never emerge out of the safepoint before the VM exits.
4608
4609 MutexLocker ml(Heap_lock);
4610
4611 VMThread::wait_for_vm_thread_exit();
4612 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4613 VMThread::destroy();
4614 }
4615
4616 // clean up ideal graph printers
4617 #if defined(COMPILER2) && !defined(PRODUCT)
4618 IdealGraphPrinter::clean_up();
4619 #endif
4620
4621 // Now, all Java threads are gone except daemon threads. Daemon threads
4622 // running Java code or in VM are stopped by the Safepoint. However,
4623 // daemon threads executing native code are still running. But they
4624 // will be stopped at native=>Java/VM barriers. Note that we can't
4625 // simply kill or suspend them, as it is inherently deadlock-prone.
4626
4627 VM_Exit::set_vm_exited();
4628
4629 notify_vm_shutdown();
4630
4631 // We are after VM_Exit::set_vm_exited() so we can't call
4632 // thread->smr_delete() or we will block on the Threads_lock.
4633 // Deleting the shutdown thread here is safe because another
4634 // JavaThread cannot have an active ThreadsListHandle for
4635 // this JavaThread.
4636 delete thread;
4637
4638 #if INCLUDE_JVMCI
4639 if (JVMCICounterSize > 0) {
4640 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4641 }
4642 #endif
4643
4644 // exit_globals() will delete tty
4645 exit_globals();
4646
4647 LogConfiguration::finalize();
4648
4649 return true;
4650 }
4651
4652
4653 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4654 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4655 return is_supported_jni_version(version);
4656 }
4657
4658
4659 jboolean Threads::is_supported_jni_version(jint version) {
4660 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4661 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4662 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4663 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4664 if (version == JNI_VERSION_9) return JNI_TRUE;
4665 if (version == JNI_VERSION_10) return JNI_TRUE;
4666 return JNI_FALSE;
4667 }
4668
4669 // Hash table of pointers found by a scan. Used for collecting hazard
4670 // pointers (ThreadsList references). Also used for collecting JavaThreads
4671 // that are indirectly referenced by hazard ptrs. An instance of this
4672 // class only contains one type of pointer.
4673 //
4674 class ThreadScanHashtable : public CHeapObj<mtThread> {
4675 private:
4676 static bool ptr_equals(void * const& s1, void * const& s2) {
4677 return s1 == s2;
4678 }
4679
4680 static unsigned int ptr_hash(void * const& s1) {
4681 // 2654435761 = 2^32 * Phi (golden ratio)
4682 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
4683 }
4684
4685 int _table_size;
4686 // ResourceHashtable SIZE is specified at compile time so our
4687 // dynamic _table_size is unused for now; 1031 is the first prime
4688 // after 1024.
4689 typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash,
4690 &ThreadScanHashtable::ptr_equals, 1031,
4691 ResourceObj::C_HEAP, mtThread> PtrTable;
4692 PtrTable * _ptrs;
4693
4694 public:
4695 // ResourceHashtable is passed to various functions and populated in
4696 // different places so we allocate it using C_HEAP to make it immune
4697 // from any ResourceMarks that happen to be in the code paths.
4698 ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {}
4699
4700 ~ThreadScanHashtable() { delete _ptrs; }
4701
4702 bool has_entry(void *pointer) {
4703 int *val_ptr = _ptrs->get(pointer);
4704 return val_ptr != NULL && *val_ptr == 1;
4705 }
4706
4707 void add_entry(void *pointer) {
4708 _ptrs->put(pointer, 1);
4709 }
4710 };
4711
4712 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4713 // (ThreadsList references) into a hash table. This closure handles part 2
4714 // of the dance - adding all the JavaThreads referenced by the hazard
4715 // pointer (ThreadsList reference) to the hash table.
4716 //
4717 class AddThreadHazardPointerThreadClosure : public ThreadClosure {
4718 private:
4719 ThreadScanHashtable *_table;
4720
4721 public:
4722 AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {}
4723
4724 virtual void do_thread(Thread *thread) {
4725 if (!_table->has_entry((void*)thread)) {
4726 // The same JavaThread might be on more than one ThreadsList or
4727 // more than one thread might be using the same ThreadsList. In
4728 // either case, we only need a single entry for a JavaThread.
4729 _table->add_entry((void*)thread);
4730 }
4731 }
4732 };
4733
4734 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4735 // (ThreadsList references) into a hash table. This closure handles part 1
4736 // of the dance - hazard ptr chain walking and dispatch to another
4737 // closure.
4738 //
4739 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure {
4740 private:
4741 ThreadScanHashtable *_table;
4742 public:
4743 ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {}
4744
4745 virtual void do_thread(Thread *thread) {
4746 assert_locked_or_safepoint(Threads_lock);
4747
4748 if (thread == NULL) return;
4749
4750 // This code races with Threads::acquire_stable_list() which is
4751 // lock-free so we have to handle some special situations.
4752 //
4753 ThreadsList *current_list = NULL;
4754 while (true) {
4755 current_list = thread->get_threads_hazard_ptr();
4756 // No hazard ptr so nothing more to do.
4757 if (current_list == NULL) {
4758 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4759 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4760 return;
4761 }
4762
4763 // If the hazard ptr is verified as stable (since it is not tagged),
4764 // then it is safe to use.
4765 if (!Thread::is_hazard_ptr_tagged(current_list)) break;
4766
4767 // The hazard ptr is tagged as not yet verified as being stable
4768 // so we are racing with acquire_stable_list(). This exchange
4769 // attempts to invalidate the hazard ptr. If we win the race,
4770 // then we can ignore this unstable hazard ptr and the other
4771 // thread will retry the attempt to publish a stable hazard ptr.
4772 // If we lose the race, then we retry our attempt to look at the
4773 // hazard ptr.
4774 if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return;
4775 }
4776
4777 // The current JavaThread has a hazard ptr (ThreadsList reference)
4778 // which might be _smr_java_thread_list or it might be an older
4779 // ThreadsList that has been removed but not freed. In either case,
4780 // the hazard ptr is protecting all the JavaThreads on that
4781 // ThreadsList.
4782 AddThreadHazardPointerThreadClosure add_cl(_table);
4783 current_list->threads_do(&add_cl);
4784
4785 // Any NestedThreadsLists are also protecting JavaThreads so
4786 // gather those also; the ThreadsLists may be different.
4787 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4788 node != NULL; node = node->next()) {
4789 node->t_list()->threads_do(&add_cl);
4790 }
4791 }
4792 };
4793
4794 // Closure to print JavaThreads that have a hazard ptr (ThreadsList
4795 // reference) that contains an indirect reference to a specific JavaThread.
4796 //
4797 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure {
4798 private:
4799 JavaThread *_thread;
4800 public:
4801 ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {}
4802
4803 virtual void do_thread(Thread *thread) {
4804 assert_locked_or_safepoint(Threads_lock);
4805
4806 if (thread == NULL) return;
4807 ThreadsList *current_list = thread->get_threads_hazard_ptr();
4808 if (current_list == NULL) {
4809 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4810 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4811 return;
4812 }
4813 // If the hazard ptr is unverified, then ignore it.
4814 if (Thread::is_hazard_ptr_tagged(current_list)) return;
4815
4816 // The current JavaThread has a hazard ptr (ThreadsList reference)
4817 // which might be _smr_java_thread_list or it might be an older
4818 // ThreadsList that has been removed but not freed. In either case,
4819 // the hazard ptr is protecting all the JavaThreads on that
4820 // ThreadsList, but we only care about matching a specific JavaThread.
4821 DO_JAVA_THREADS(current_list, p) {
4822 if (p == _thread) {
4823 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread));
4824 break;
4825 }
4826 }
4827
4828 // Any NestedThreadsLists are also protecting JavaThreads so
4829 // check those also; the ThreadsLists may be different.
4830 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4831 node != NULL; node = node->next()) {
4832 DO_JAVA_THREADS(node->t_list(), p) {
4833 if (p == _thread) {
4834 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a nested hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread));
4835 return;
4836 }
4837 }
4838 }
4839 }
4840 };
4841
4842 // Return true if the specified JavaThread is protected by a hazard
4843 // pointer (ThreadsList reference). Otherwise, returns false.
4844 //
4845 bool Threads::is_a_protected_JavaThread(JavaThread *thread) {
4846 assert_locked_or_safepoint(Threads_lock);
4847
4848 // Hash table size should be first power of two higher than twice
4849 // the length of the Threads list.
4850 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4851 hash_table_size--;
4852 hash_table_size |= hash_table_size >> 1;
4853 hash_table_size |= hash_table_size >> 2;
4854 hash_table_size |= hash_table_size >> 4;
4855 hash_table_size |= hash_table_size >> 8;
4856 hash_table_size |= hash_table_size >> 16;
4857 hash_table_size++;
4858
4859 // Gather a hash table of the JavaThreads indirectly referenced by
4860 // hazard ptrs.
4861 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4862 ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table);
4863 Threads::threads_do(&scan_cl);
4864
4865 bool thread_is_protected = false;
4866 if (scan_table->has_entry((void*)thread)) {
4867 thread_is_protected = true;
4868 }
4869 delete scan_table;
4870 return thread_is_protected;
4871 }
4872
4873 // Safely delete a JavaThread when it is no longer in use by a
4874 // ThreadsListHandle.
4875 //
4876 void Threads::smr_delete(JavaThread *thread) {
4877 assert(!Threads_lock->owned_by_self(), "sanity");
4878
4879 bool has_logged_once = false;
4880 elapsedTimer timer;
4881 if (EnableThreadSMRStatistics) {
4882 timer.start();
4883 }
4884
4885 while (true) {
4886 {
4887 // No safepoint check because this JavaThread is not on the
4888 // Threads list.
4889 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
4890 // Cannot use a MonitorLockerEx helper here because we have
4891 // to drop the Threads_lock first if we wait.
4892 Threads::smr_delete_lock()->lock_without_safepoint_check();
4893 // Set the smr_delete_notify flag after we grab smr_delete_lock
4894 // and before we scan hazard ptrs because we're doing
4895 // double-check locking in release_stable_list().
4896 Threads::set_smr_delete_notify();
4897
4898 if (!is_a_protected_JavaThread(thread)) {
4899 // This is the common case.
4900 Threads::clear_smr_delete_notify();
4901 Threads::smr_delete_lock()->unlock();
4902 break;
4903 }
4904 if (!has_logged_once) {
4905 has_logged_once = true;
4906 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread));
4907 if (log_is_enabled(Debug, os, thread)) {
4908 ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread);
4909 Threads::threads_do(&scan_cl);
4910 }
4911 }
4912 } // We have to drop the Threads_lock to wait or delete the thread
4913
4914 if (EnableThreadSMRStatistics) {
4915 _smr_delete_lock_wait_cnt++;
4916 if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) {
4917 _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt;
4918 }
4919 }
4920 // Wait for a release_stable_list() call before we check again. No
4921 // safepoint check, no timeout, and not as suspend equivalent flag
4922 // because this JavaThread is not on the Threads list.
4923 Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0,
4924 !Mutex::_as_suspend_equivalent_flag);
4925 if (EnableThreadSMRStatistics) {
4926 _smr_delete_lock_wait_cnt--;
4927 }
4928
4929 Threads::clear_smr_delete_notify();
4930 Threads::smr_delete_lock()->unlock();
4931 // Retry the whole scenario.
4932 }
4933
4934 if (ThreadLocalHandshakes) {
4935 // The thread is about to be deleted so cancel any handshake.
4936 thread->cancel_handshake();
4937 }
4938
4939 delete thread;
4940 if (EnableThreadSMRStatistics) {
4941 timer.stop();
4942 uint millis = (uint)timer.milliseconds();
4943 Threads::inc_smr_deleted_thread_cnt();
4944 Threads::add_smr_deleted_thread_times(millis);
4945 Threads::update_smr_deleted_thread_time_max(millis);
4946 }
4947
4948 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread));
4949 }
4950
4951 bool Threads::smr_delete_notify() {
4952 // Use load_acquire() in order to see any updates to _smr_delete_notify
4953 // earlier than when smr_delete_lock is grabbed.
4954 return (OrderAccess::load_acquire(&_smr_delete_notify) != 0);
4955 }
4956
4957 // set_smr_delete_notify() and clear_smr_delete_notify() are called
4958 // under the protection of the smr_delete_lock, but we also use an
4959 // Atomic operation to ensure the memory update is seen earlier than
4960 // when the smr_delete_lock is dropped.
4961 //
4962 void Threads::set_smr_delete_notify() {
4963 Atomic::inc(&_smr_delete_notify);
4964 }
4965
4966 void Threads::clear_smr_delete_notify() {
4967 Atomic::dec(&_smr_delete_notify);
4968 }
4969
4970 // Closure to gather hazard ptrs (ThreadsList references) into a hash table.
4971 //
4972 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure {
4973 private:
4974 ThreadScanHashtable *_table;
4975 public:
4976 ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {}
4977
4978 virtual void do_thread(Thread* thread) {
4979 assert_locked_or_safepoint(Threads_lock);
4980
4981 if (thread == NULL) return;
4982 ThreadsList *threads = thread->get_threads_hazard_ptr();
4983 if (threads == NULL) {
4984 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4985 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4986 return;
4987 }
4988 // In this closure we always ignore the tag that might mark this
4989 // hazard ptr as not yet verified. If we happen to catch an
4990 // unverified hazard ptr that is subsequently discarded (not
4991 // published), then the only side effect is that we might keep a
4992 // to-be-deleted ThreadsList alive a little longer.
4993 threads = Thread::untag_hazard_ptr(threads);
4994 if (!_table->has_entry((void*)threads)) {
4995 _table->add_entry((void*)threads);
4996 }
4997
4998 // Any NestedThreadsLists are also protecting JavaThreads so
4999 // gather those also; the ThreadsLists may be different.
5000 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
5001 node != NULL; node = node->next()) {
5002 threads = node->t_list();
5003 if (!_table->has_entry((void*)threads)) {
5004 _table->add_entry((void*)threads);
5005 }
5006 }
5007 }
5008 };
5009
5010 // Safely free a ThreadsList after a Threads::add() or Threads::remove().
5011 // The specified ThreadsList may not get deleted during this call if it
5012 // is still in-use (referenced by a hazard ptr). Other ThreadsLists
5013 // in the chain may get deleted by this call if they are no longer in-use.
5014 void Threads::smr_free_list(ThreadsList* threads) {
5015 assert_locked_or_safepoint(Threads_lock);
5016
5017 threads->set_next_list(_smr_to_delete_list);
5018 _smr_to_delete_list = threads;
5019 if (EnableThreadSMRStatistics) {
5020 _smr_to_delete_list_cnt++;
5021 if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) {
5022 _smr_to_delete_list_max = _smr_to_delete_list_cnt;
5023 }
5024 }
5025
5026 // Hash table size should be first power of two higher than twice the length of the ThreadsList
5027 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
5028 hash_table_size--;
5029 hash_table_size |= hash_table_size >> 1;
5030 hash_table_size |= hash_table_size >> 2;
5031 hash_table_size |= hash_table_size >> 4;
5032 hash_table_size |= hash_table_size >> 8;
5033 hash_table_size |= hash_table_size >> 16;
5034 hash_table_size++;
5035
5036 // Gather a hash table of the current hazard ptrs:
5037 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
5038 ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table);
5039 Threads::threads_do(&scan_cl);
5040
5041 // Walk through the linked list of pending freeable ThreadsLists
5042 // and free the ones that are not referenced from hazard ptrs.
5043 ThreadsList* current = _smr_to_delete_list;
5044 ThreadsList* prev = NULL;
5045 ThreadsList* next = NULL;
5046 bool threads_is_freed = false;
5047 while (current != NULL) {
5048 next = current->next_list();
5049 if (!scan_table->has_entry((void*)current)) {
5050 // This ThreadsList is not referenced by a hazard ptr.
5051 if (prev != NULL) {
5052 prev->set_next_list(next);
5053 }
5054 if (_smr_to_delete_list == current) {
5055 _smr_to_delete_list = next;
5056 }
5057
5058 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current));
5059 if (current == threads) threads_is_freed = true;
5060 delete current;
5061 if (EnableThreadSMRStatistics) {
5062 _smr_java_thread_list_free_cnt++;
5063 _smr_to_delete_list_cnt--;
5064 }
5065 } else {
5066 prev = current;
5067 }
5068 current = next;
5069 }
5070
5071 if (!threads_is_freed) {
5072 // Only report "is not freed" on the original call to
5073 // smr_free_list() for this ThreadsList.
5074 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads));
5075 }
5076
5077 delete scan_table;
5078 }
5079
5080 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a
5081 // new copy of the specified ThreadsList with the specified JavaThread
5082 // removed.
5083 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) {
5084 assert(list->_length > 0, "sanity");
5085
5086 uint i = 0;
5087 DO_JAVA_THREADS(list, current) {
5088 if (current == java_thread) {
5089 break;
5090 }
5091 i++;
5092 }
5093 assert(i < list->_length, "did not find JavaThread on the list");
5094 const uint index = i;
5095 const uint new_length = list->_length - 1;
5096 const uint head_length = index;
5097 const uint tail_length = (new_length >= index) ? (new_length - index) : 0;
5098 ThreadsList *const new_list = new ThreadsList(new_length);
5099
5100 if (head_length > 0) {
5101 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5102 }
5103 if (tail_length > 0) {
5104 Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length);
5105 }
5106
5107 return new_list;
5108 }
5109
5110 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a
5111 // new copy of the specified ThreadsList with the specified JavaThread
5112 // appended to the end.
5113 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) {
5114 const uint index = list->_length;
5115 const uint new_length = index + 1;
5116 const uint head_length = index;
5117 ThreadsList *const new_list = new ThreadsList(new_length);
5118
5119 if (head_length > 0) {
5120 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5121 }
5122 *(JavaThread**)(new_list->_threads + index) = java_thread;
5123
5124 return new_list;
5125 }
5126
5127 int ThreadsList::find_index_of_JavaThread(JavaThread *target) {
5128 if (target == NULL) {
5129 return -1;
5130 }
5131 for (uint i = 0; i < length(); i++) {
5132 if (target == thread_at(i)) {
5133 return (int)i;
5134 }
5135 }
5136 return -1;
5137 }
5138
5139 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const {
5140 DO_JAVA_THREADS(this, thread) {
5141 oop tobj = thread->threadObj();
5142 // Ignore the thread if it hasn't run yet, has exited
5143 // or is starting to exit.
5144 if (tobj != NULL && !thread->is_exiting() &&
5145 java_tid == java_lang_Thread::thread_id(tobj)) {
5146 // found a match
5147 return thread;
5148 }
5149 }
5150 return NULL;
5151 }
5152
5153 bool ThreadsList::includes(const JavaThread * const p) const {
5154 if (p == NULL) {
5155 return false;
5156 }
5157 DO_JAVA_THREADS(this, q) {
5158 if (q == p) {
5159 return true;
5160 }
5161 }
5162 return false;
5163 }
5164
5165 void Threads::add(JavaThread* p, bool force_daemon) {
5166 // The threads lock must be owned at this point
5167 assert_locked_or_safepoint(Threads_lock);
5168
5169 // See the comment for this method in thread.hpp for its purpose and
5170 // why it is called here.
5171 p->initialize_queues();
5172 p->set_next(_thread_list);
5173 _thread_list = p;
5174
5175 // Once a JavaThread is added to the Threads list, smr_delete() has
5176 // to be used to delete it. Otherwise we can just delete it directly.
5177 p->set_on_thread_list();
5178
5179 _number_of_threads++;
5180 oop threadObj = p->threadObj();
5181 bool daemon = true;
5182 // Bootstrapping problem: threadObj can be null for initial
5183 // JavaThread (or for threads attached via JNI)
5184 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
5185 _number_of_non_daemon_threads++;
5186 daemon = false;
5187 }
5188
5189 ThreadService::add_thread(p, daemon);
5190
5191 // Maintain fast thread list
5192 ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p);
5193 if (EnableThreadSMRStatistics) {
5194 _smr_java_thread_list_alloc_cnt++;
5195 if (new_list->length() > _smr_java_thread_list_max) {
5196 _smr_java_thread_list_max = new_list->length();
5197 }
5198 }
5199 // Initial _smr_java_thread_list will not generate a "Threads::add" mesg.
5200 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5201
5202 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5203 smr_free_list(old_list);
5204
5205 // Possible GC point.
5206 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
5207 }
5208
5209 void Threads::remove(JavaThread* p) {
5210
5211 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
5212 ObjectSynchronizer::omFlush(p);
5213
5214 // Extra scope needed for Thread_lock, so we can check
5215 // that we do not remove thread without safepoint code notice
5216 { MutexLocker ml(Threads_lock);
5217
5218 assert(get_smr_java_thread_list()->includes(p), "p must be present");
5219
5220 // Maintain fast thread list
5221 ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p);
5222 if (EnableThreadSMRStatistics) {
5223 _smr_java_thread_list_alloc_cnt++;
5224 // This list is smaller so no need to check for a "longest" update.
5225 }
5226
5227 // Final _smr_java_thread_list will not generate a "Threads::remove" mesg.
5228 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5229
5230 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5231 smr_free_list(old_list);
5232
5233 JavaThread* current = _thread_list;
5234 JavaThread* prev = NULL;
5235
5236 while (current != p) {
5237 prev = current;
5238 current = current->next();
5239 }
5240
5241 if (prev) {
5242 prev->set_next(current->next());
5243 } else {
5244 _thread_list = p->next();
5245 }
5246
5247 _number_of_threads--;
5248 oop threadObj = p->threadObj();
5249 bool daemon = true;
5250 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
5251 _number_of_non_daemon_threads--;
5252 daemon = false;
5253
5254 // Only one thread left, do a notify on the Threads_lock so a thread waiting
5255 // on destroy_vm will wake up.
5256 if (number_of_non_daemon_threads() == 1) {
5257 Threads_lock->notify_all();
5258 }
5259 }
5260 ThreadService::remove_thread(p, daemon);
5261
5262 // Make sure that safepoint code disregard this thread. This is needed since
5263 // the thread might mess around with locks after this point. This can cause it
5264 // to do callbacks into the safepoint code. However, the safepoint code is not aware
5265 // of this thread since it is removed from the queue.
5266 p->set_terminated_value();
5267 } // unlock Threads_lock
5268
5269 // Since Events::log uses a lock, we grab it outside the Threads_lock
5270 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
5271 }
5272
5273 // Operations on the Threads list for GC. These are not explicitly locked,
5274 // but the garbage collector must provide a safe context for them to run.
5275 // In particular, these things should never be called when the Threads_lock
5276 // is held by some other thread. (Note: the Safepoint abstraction also
5277 // uses the Threads_lock to guarantee this property. It also makes sure that
5278 // all threads gets blocked when exiting or starting).
5279
5280 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
5281 ALL_JAVA_THREADS(p) {
5282 p->oops_do(f, cf);
5283 }
5284 VMThread::vm_thread()->oops_do(f, cf);
5285 }
5286
5287 void Threads::change_thread_claim_parity() {
5288 // Set the new claim parity.
5289 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
5290 "Not in range.");
5291 _thread_claim_parity++;
5292 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
5293 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
5294 "Not in range.");
5295 }
5296
5297 #ifdef ASSERT
5298 void Threads::assert_all_threads_claimed() {
5299 ALL_JAVA_THREADS(p) {
5300 const int thread_parity = p->oops_do_parity();
5301 assert((thread_parity == _thread_claim_parity),
5302 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
5303 }
5304 VMThread* vmt = VMThread::vm_thread();
5305 const int thread_parity = vmt->oops_do_parity();
5306 assert((thread_parity == _thread_claim_parity),
5307 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
5308 }
5309 #endif // ASSERT
5310
5311 class ParallelOopsDoThreadClosure : public ThreadClosure {
5312 private:
5313 OopClosure* _f;
5314 CodeBlobClosure* _cf;
5315 public:
5316 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
5317 void do_thread(Thread* t) {
5318 t->oops_do(_f, _cf);
5319 }
5320 };
5321
5322 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
5323 ParallelOopsDoThreadClosure tc(f, cf);
5324 possibly_parallel_threads_do(is_par, &tc);
5325 }
5326
5327 #if INCLUDE_ALL_GCS
5328 // Used by ParallelScavenge
5329 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
5330 ALL_JAVA_THREADS(p) {
5331 q->enqueue(new ThreadRootsTask(p));
5332 }
5333 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
5334 }
5335
5336 // Used by Parallel Old
5337 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
5338 ALL_JAVA_THREADS(p) {
5339 q->enqueue(new ThreadRootsMarkingTask(p));
5340 }
5341 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
5342 }
5343 #endif // INCLUDE_ALL_GCS
5344
5345 void Threads::nmethods_do(CodeBlobClosure* cf) {
5346 ALL_JAVA_THREADS(p) {
5347 // This is used by the code cache sweeper to mark nmethods that are active
5348 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
5349 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
5350 if(!p->is_Code_cache_sweeper_thread()) {
5351 p->nmethods_do(cf);
5352 }
5353 }
5354 }
5355
5356 void Threads::metadata_do(void f(Metadata*)) {
5357 ALL_JAVA_THREADS(p) {
5358 p->metadata_do(f);
5359 }
5360 }
5361
5362 class ThreadHandlesClosure : public ThreadClosure {
5363 void (*_f)(Metadata*);
5364 public:
5365 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
5366 virtual void do_thread(Thread* thread) {
5367 thread->metadata_handles_do(_f);
5368 }
5369 };
5370
5371 void Threads::metadata_handles_do(void f(Metadata*)) {
5372 // Only walk the Handles in Thread.
5373 ThreadHandlesClosure handles_closure(f);
5374 threads_do(&handles_closure);
5375 }
5376
5377 void Threads::deoptimized_wrt_marked_nmethods() {
5378 ALL_JAVA_THREADS(p) {
5379 p->deoptimized_wrt_marked_nmethods();
5380 }
5381 }
5382
5383
5384 // Get count Java threads that are waiting to enter the specified monitor.
5385 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
5386 int count,
5387 address monitor) {
5388 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
5389
5390 int i = 0;
5391 DO_JAVA_THREADS(t_list, p) {
5392 if (!p->can_call_java()) continue;
5393
5394 address pending = (address)p->current_pending_monitor();
5395 if (pending == monitor) { // found a match
5396 if (i < count) result->append(p); // save the first count matches
5397 i++;
5398 }
5399 }
5400
5401 return result;
5402 }
5403
5404
5405 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
5406 address owner) {
5407 // NULL owner means not locked so we can skip the search
5408 if (owner == NULL) return NULL;
5409
5410 DO_JAVA_THREADS(t_list, p) {
5411 // first, see if owner is the address of a Java thread
5412 if (owner == (address)p) return p;
5413 }
5414
5415 // Cannot assert on lack of success here since this function may be
5416 // used by code that is trying to report useful problem information
5417 // like deadlock detection.
5418 if (UseHeavyMonitors) return NULL;
5419
5420 // If we didn't find a matching Java thread and we didn't force use of
5421 // heavyweight monitors, then the owner is the stack address of the
5422 // Lock Word in the owning Java thread's stack.
5423 //
5424 JavaThread* the_owner = NULL;
5425 DO_JAVA_THREADS(t_list, q) {
5426 if (q->is_lock_owned(owner)) {
5427 the_owner = q;
5428 break;
5429 }
5430 }
5431
5432 // cannot assert on lack of success here; see above comment
5433 return the_owner;
5434 }
5435
5436 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
5437 void Threads::print_on(outputStream* st, bool print_stacks,
5438 bool internal_format, bool print_concurrent_locks) {
5439 char buf[32];
5440 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
5441
5442 st->print_cr("Full thread dump %s (%s %s):",
5443 Abstract_VM_Version::vm_name(),
5444 Abstract_VM_Version::vm_release(),
5445 Abstract_VM_Version::vm_info_string());
5446 st->cr();
5447
5448 #if INCLUDE_SERVICES
5449 // Dump concurrent locks
5450 ConcurrentLocksDump concurrent_locks;
5451 if (print_concurrent_locks) {
5452 concurrent_locks.dump_at_safepoint();
5453 }
5454 #endif // INCLUDE_SERVICES
5455
5456 print_smr_info_on(st);
5457 st->cr();
5458
5459 ALL_JAVA_THREADS(p) {
5460 ResourceMark rm;
5461 p->print_on(st);
5462 if (print_stacks) {
5463 if (internal_format) {
5464 p->trace_stack();
5465 } else {
5466 p->print_stack_on(st);
5467 }
5468 }
5469 st->cr();
5470 #if INCLUDE_SERVICES
5471 if (print_concurrent_locks) {
5472 concurrent_locks.print_locks_on(p, st);
5473 }
5474 #endif // INCLUDE_SERVICES
5475 }
5476
5477 VMThread::vm_thread()->print_on(st);
5478 st->cr();
5479 Universe::heap()->print_gc_threads_on(st);
5480 WatcherThread* wt = WatcherThread::watcher_thread();
5481 if (wt != NULL) {
5482 wt->print_on(st);
5483 st->cr();
5484 }
5485
5486 st->flush();
5487 }
5488
5489 // Log Threads class SMR info.
5490 void Threads::log_smr_statistics() {
5491 LogTarget(Info, thread, smr) log;
5492 if (log.is_enabled()) {
5493 LogStream out(log);
5494 print_smr_info_on(&out);
5495 }
5496 }
5497
5498 // Print Threads class SMR info.
5499 void Threads::print_smr_info_on(outputStream* st) {
5500 // Only grab the Threads_lock if we don't already own it
5501 // and if we are not reporting an error.
5502 MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock);
5503
5504 st->print_cr("Threads class SMR info:");
5505 st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, "
5506 "elements={", p2i(_smr_java_thread_list),
5507 _smr_java_thread_list->length());
5508 print_smr_info_elements_on(st, _smr_java_thread_list);
5509 st->print_cr("}");
5510 if (_smr_to_delete_list != NULL) {
5511 st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, "
5512 "elements={", p2i(_smr_to_delete_list),
5513 _smr_to_delete_list->length());
5514 print_smr_info_elements_on(st, _smr_to_delete_list);
5515 st->print_cr("}");
5516 for (ThreadsList *t_list = _smr_to_delete_list->next_list();
5517 t_list != NULL; t_list = t_list->next_list()) {
5518 st->print("next-> " INTPTR_FORMAT ", length=%u, "
5519 "elements={", p2i(t_list), t_list->length());
5520 print_smr_info_elements_on(st, t_list);
5521 st->print_cr("}");
5522 }
5523 }
5524 if (!EnableThreadSMRStatistics) {
5525 return;
5526 }
5527 st->print_cr("_smr_java_thread_list_alloc_cnt=" UINT64_FORMAT ","
5528 "_smr_java_thread_list_free_cnt=" UINT64_FORMAT ","
5529 "_smr_java_thread_list_max=%u, "
5530 "_smr_nested_thread_list_max=%u",
5531 _smr_java_thread_list_alloc_cnt,
5532 _smr_java_thread_list_free_cnt,
5533 _smr_java_thread_list_max,
5534 _smr_nested_thread_list_max);
5535 if (_smr_tlh_cnt > 0) {
5536 st->print_cr("_smr_tlh_cnt=%u"
5537 ", _smr_tlh_times=%u"
5538 ", avg_smr_tlh_time=%0.2f"
5539 ", _smr_tlh_time_max=%u",
5540 _smr_tlh_cnt, _smr_tlh_times,
5541 ((double) _smr_tlh_times / _smr_tlh_cnt),
5542 _smr_tlh_time_max);
5543 }
5544 if (_smr_deleted_thread_cnt > 0) {
5545 st->print_cr("_smr_deleted_thread_cnt=%u"
5546 ", _smr_deleted_thread_times=%u"
5547 ", avg_smr_deleted_thread_time=%0.2f"
5548 ", _smr_deleted_thread_time_max=%u",
5549 _smr_deleted_thread_cnt, _smr_deleted_thread_times,
5550 ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt),
5551 _smr_deleted_thread_time_max);
5552 }
5553 st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u",
5554 _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max);
5555 st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u",
5556 _smr_to_delete_list_cnt, _smr_to_delete_list_max);
5557 }
5558
5559 // Print ThreadsList elements (4 per line).
5560 void Threads::print_smr_info_elements_on(outputStream* st,
5561 ThreadsList* t_list) {
5562 uint cnt = 0;
5563 JavaThreadIterator jti(t_list);
5564 for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) {
5565 st->print(INTPTR_FORMAT, p2i(jt));
5566 if (cnt < t_list->length() - 1) {
5567 // Separate with comma or comma-space except for the last one.
5568 if (((cnt + 1) % 4) == 0) {
5569 // Four INTPTR_FORMAT fit on an 80 column line so end the
5570 // current line with just a comma.
5571 st->print_cr(",");
5572 } else {
5573 // Not the last one on the current line so use comma-space:
5574 st->print(", ");
5575 }
5576 } else {
5577 // Last one so just end the current line.
5578 st->cr();
5579 }
5580 cnt++;
5581 }
5582 }
5583
5584 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
5585 int buflen, bool* found_current) {
5586 if (this_thread != NULL) {
5587 bool is_current = (current == this_thread);
5588 *found_current = *found_current || is_current;
5589 st->print("%s", is_current ? "=>" : " ");
5590
5591 st->print(PTR_FORMAT, p2i(this_thread));
5592 st->print(" ");
5593 this_thread->print_on_error(st, buf, buflen);
5594 st->cr();
5595 }
5596 }
5597
5598 class PrintOnErrorClosure : public ThreadClosure {
5599 outputStream* _st;
5600 Thread* _current;
5601 char* _buf;
5602 int _buflen;
5603 bool* _found_current;
5604 public:
5605 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
5606 int buflen, bool* found_current) :
5607 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
5608
5609 virtual void do_thread(Thread* thread) {
5610 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
5611 }
5612 };
5613
5614 // Threads::print_on_error() is called by fatal error handler. It's possible
5615 // that VM is not at safepoint and/or current thread is inside signal handler.
5616 // Don't print stack trace, as the stack may not be walkable. Don't allocate
5617 // memory (even in resource area), it might deadlock the error handler.
5618 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
5619 int buflen) {
5620 print_smr_info_on(st);
5621 st->cr();
5622
5623 bool found_current = false;
5624 st->print_cr("Java Threads: ( => current thread )");
5625 ALL_JAVA_THREADS(thread) {
5626 print_on_error(thread, st, current, buf, buflen, &found_current);
5627 }
5628 st->cr();
5629
5630 st->print_cr("Other Threads:");
5631 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
5632 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
5633
5634 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
5635 Universe::heap()->gc_threads_do(&print_closure);
5636
5637 if (!found_current) {
5638 st->cr();
5639 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
5640 current->print_on_error(st, buf, buflen);
5641 st->cr();
5642 }
5643 st->cr();
5644
5645 st->print_cr("Threads with active compile tasks:");
5646 print_threads_compiling(st, buf, buflen);
5647 }
5648
5649 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
5650 ALL_JAVA_THREADS(thread) {
5651 if (thread->is_Compiler_thread()) {
5652 CompilerThread* ct = (CompilerThread*) thread;
5653 if (ct->task() != NULL) {
5654 thread->print_name_on_error(st, buf, buflen);
5655 ct->task()->print(st, NULL, true, true);
5656 }
5657 }
5658 }
5659 }
5660
5661
5662 // Internal SpinLock and Mutex
5663 // Based on ParkEvent
5664
5665 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
5666 //
5667 // We employ SpinLocks _only for low-contention, fixed-length
5668 // short-duration critical sections where we're concerned
5669 // about native mutex_t or HotSpot Mutex:: latency.
5670 // The mux construct provides a spin-then-block mutual exclusion
5671 // mechanism.
5672 //
5673 // Testing has shown that contention on the ListLock guarding gFreeList
5674 // is common. If we implement ListLock as a simple SpinLock it's common
5675 // for the JVM to devolve to yielding with little progress. This is true
5676 // despite the fact that the critical sections protected by ListLock are
5677 // extremely short.
5678 //
5679 // TODO-FIXME: ListLock should be of type SpinLock.
5680 // We should make this a 1st-class type, integrated into the lock
5681 // hierarchy as leaf-locks. Critically, the SpinLock structure
5682 // should have sufficient padding to avoid false-sharing and excessive
5683 // cache-coherency traffic.
5684
5685
5686 typedef volatile int SpinLockT;
5687
5688 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
5689 if (Atomic::cmpxchg (1, adr, 0) == 0) {
5690 return; // normal fast-path return
5691 }
5692
5693 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
5694 TEVENT(SpinAcquire - ctx);
5695 int ctr = 0;
5696 int Yields = 0;
5697 for (;;) {
5698 while (*adr != 0) {
5699 ++ctr;
5700 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
5701 if (Yields > 5) {
5702 os::naked_short_sleep(1);
5703 } else {
5704 os::naked_yield();
5705 ++Yields;
5706 }
5707 } else {
5708 SpinPause();
5709 }
5710 }
5711 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
5712 }
5713 }
5714
5715 void Thread::SpinRelease(volatile int * adr) {
5716 assert(*adr != 0, "invariant");
5717 OrderAccess::fence(); // guarantee at least release consistency.
5718 // Roach-motel semantics.
5719 // It's safe if subsequent LDs and STs float "up" into the critical section,
5720 // but prior LDs and STs within the critical section can't be allowed
5721 // to reorder or float past the ST that releases the lock.
5722 // Loads and stores in the critical section - which appear in program
5723 // order before the store that releases the lock - must also appear
5724 // before the store that releases the lock in memory visibility order.
5725 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
5726 // the ST of 0 into the lock-word which releases the lock, so fence
5727 // more than covers this on all platforms.
5728 *adr = 0;
5729 }
5730
5731 // muxAcquire and muxRelease:
5732 //
5733 // * muxAcquire and muxRelease support a single-word lock-word construct.
5734 // The LSB of the word is set IFF the lock is held.
5735 // The remainder of the word points to the head of a singly-linked list
5736 // of threads blocked on the lock.
5737 //
5738 // * The current implementation of muxAcquire-muxRelease uses its own
5739 // dedicated Thread._MuxEvent instance. If we're interested in
5740 // minimizing the peak number of extant ParkEvent instances then
5741 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5742 // as certain invariants were satisfied. Specifically, care would need
5743 // to be taken with regards to consuming unpark() "permits".
5744 // A safe rule of thumb is that a thread would never call muxAcquire()
5745 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5746 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
5747 // consume an unpark() permit intended for monitorenter, for instance.
5748 // One way around this would be to widen the restricted-range semaphore
5749 // implemented in park(). Another alternative would be to provide
5750 // multiple instances of the PlatformEvent() for each thread. One
5751 // instance would be dedicated to muxAcquire-muxRelease, for instance.
5752 //
5753 // * Usage:
5754 // -- Only as leaf locks
5755 // -- for short-term locking only as muxAcquire does not perform
5756 // thread state transitions.
5757 //
5758 // Alternatives:
5759 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
5760 // but with parking or spin-then-park instead of pure spinning.
5761 // * Use Taura-Oyama-Yonenzawa locks.
5762 // * It's possible to construct a 1-0 lock if we encode the lockword as
5763 // (List,LockByte). Acquire will CAS the full lockword while Release
5764 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
5765 // acquiring threads use timers (ParkTimed) to detect and recover from
5766 // the stranding window. Thread/Node structures must be aligned on 256-byte
5767 // boundaries by using placement-new.
5768 // * Augment MCS with advisory back-link fields maintained with CAS().
5769 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5770 // The validity of the backlinks must be ratified before we trust the value.
5771 // If the backlinks are invalid the exiting thread must back-track through the
5772 // the forward links, which are always trustworthy.
5773 // * Add a successor indication. The LockWord is currently encoded as
5774 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
5775 // to provide the usual futile-wakeup optimization.
5776 // See RTStt for details.
5777 // * Consider schedctl.sc_nopreempt to cover the critical section.
5778 //
5779
5780
5781 const intptr_t LOCKBIT = 1;
5782
5783 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5784 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5785 if (w == 0) return;
5786 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5787 return;
5788 }
5789
5790 TEVENT(muxAcquire - Contention);
5791 ParkEvent * const Self = Thread::current()->_MuxEvent;
5792 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5793 for (;;) {
5794 int its = (os::is_MP() ? 100 : 0) + 1;
5795
5796 // Optional spin phase: spin-then-park strategy
5797 while (--its >= 0) {
5798 w = *Lock;
5799 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5800 return;
5801 }
5802 }
5803
5804 Self->reset();
5805 Self->OnList = intptr_t(Lock);
5806 // The following fence() isn't _strictly necessary as the subsequent
5807 // CAS() both serializes execution and ratifies the fetched *Lock value.
5808 OrderAccess::fence();
5809 for (;;) {
5810 w = *Lock;
5811 if ((w & LOCKBIT) == 0) {
5812 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5813 Self->OnList = 0; // hygiene - allows stronger asserts
5814 return;
5815 }
5816 continue; // Interference -- *Lock changed -- Just retry
5817 }
5818 assert(w & LOCKBIT, "invariant");
5819 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5820 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5821 }
5822
5823 while (Self->OnList != 0) {
5824 Self->park();
5825 }
5826 }
5827 }
5828
5829 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5830 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5831 if (w == 0) return;
5832 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5833 return;
5834 }
5835
5836 TEVENT(muxAcquire - Contention);
5837 ParkEvent * ReleaseAfter = NULL;
5838 if (ev == NULL) {
5839 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5840 }
5841 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5842 for (;;) {
5843 guarantee(ev->OnList == 0, "invariant");
5844 int its = (os::is_MP() ? 100 : 0) + 1;
5845
5846 // Optional spin phase: spin-then-park strategy
5847 while (--its >= 0) {
5848 w = *Lock;
5849 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5850 if (ReleaseAfter != NULL) {
5851 ParkEvent::Release(ReleaseAfter);
5852 }
5853 return;
5854 }
5855 }
5856
5857 ev->reset();
5858 ev->OnList = intptr_t(Lock);
5859 // The following fence() isn't _strictly necessary as the subsequent
5860 // CAS() both serializes execution and ratifies the fetched *Lock value.
5861 OrderAccess::fence();
5862 for (;;) {
5863 w = *Lock;
5864 if ((w & LOCKBIT) == 0) {
5865 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5866 ev->OnList = 0;
5867 // We call ::Release while holding the outer lock, thus
5868 // artificially lengthening the critical section.
5869 // Consider deferring the ::Release() until the subsequent unlock(),
5870 // after we've dropped the outer lock.
5871 if (ReleaseAfter != NULL) {
5872 ParkEvent::Release(ReleaseAfter);
5873 }
5874 return;
5875 }
5876 continue; // Interference -- *Lock changed -- Just retry
5877 }
5878 assert(w & LOCKBIT, "invariant");
5879 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5880 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5881 }
5882
5883 while (ev->OnList != 0) {
5884 ev->park();
5885 }
5886 }
5887 }
5888
5889 // Release() must extract a successor from the list and then wake that thread.
5890 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5891 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5892 // Release() would :
5893 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5894 // (B) Extract a successor from the private list "in-hand"
5895 // (C) attempt to CAS() the residual back into *Lock over null.
5896 // If there were any newly arrived threads and the CAS() would fail.
5897 // In that case Release() would detach the RATs, re-merge the list in-hand
5898 // with the RATs and repeat as needed. Alternately, Release() might
5899 // detach and extract a successor, but then pass the residual list to the wakee.
5900 // The wakee would be responsible for reattaching and remerging before it
5901 // competed for the lock.
5902 //
5903 // Both "pop" and DMR are immune from ABA corruption -- there can be
5904 // multiple concurrent pushers, but only one popper or detacher.
5905 // This implementation pops from the head of the list. This is unfair,
5906 // but tends to provide excellent throughput as hot threads remain hot.
5907 // (We wake recently run threads first).
5908 //
5909 // All paths through muxRelease() will execute a CAS.
5910 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5911 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5912 // executed within the critical section are complete and globally visible before the
5913 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5914 void Thread::muxRelease(volatile intptr_t * Lock) {
5915 for (;;) {
5916 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5917 assert(w & LOCKBIT, "invariant");
5918 if (w == LOCKBIT) return;
5919 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5920 assert(List != NULL, "invariant");
5921 assert(List->OnList == intptr_t(Lock), "invariant");
5922 ParkEvent * const nxt = List->ListNext;
5923 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5924
5925 // The following CAS() releases the lock and pops the head element.
5926 // The CAS() also ratifies the previously fetched lock-word value.
5927 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5928 continue;
5929 }
5930 List->OnList = 0;
5931 OrderAccess::fence();
5932 List->unpark();
5933 return;
5934 }
5935 }
5936
5937
5938 void Threads::verify() {
5939 ALL_JAVA_THREADS(p) {
5940 p->verify();
5941 }
5942 VMThread* thread = VMThread::vm_thread();
5943 if (thread != NULL) thread->verify();
5944 }