1 /*
2 * Copyright (c) 1997, 2018, 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/vmError.hpp"
111 #if INCLUDE_ALL_GCS
112 #include "gc/cms/concurrentMarkSweepThread.hpp"
113 #include "gc/g1/concurrentMarkThread.inline.hpp"
114 #include "gc/parallel/pcTasks.hpp"
115 #endif // INCLUDE_ALL_GCS
116 #if INCLUDE_JVMCI
117 #include "jvmci/jvmciCompiler.hpp"
118 #include "jvmci/jvmciRuntime.hpp"
119 #include "logging/logHandle.hpp"
120 #endif
121 #ifdef COMPILER1
122 #include "c1/c1_Compiler.hpp"
123 #endif
124 #ifdef COMPILER2
125 #include "opto/c2compiler.hpp"
126 #include "opto/idealGraphPrinter.hpp"
127 #endif
128 #if INCLUDE_RTM_OPT
129 #include "runtime/rtmLocking.hpp"
130 #endif
131
132 // Initialization after module runtime initialization
133 void universe_post_module_init(); // must happen after call_initPhase2
134
135 #ifdef DTRACE_ENABLED
136
137 // Only bother with this argument setup if dtrace is available
138
139 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
140 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
141
142 #define DTRACE_THREAD_PROBE(probe, javathread) \
143 { \
144 ResourceMark rm(this); \
145 int len = 0; \
146 const char* name = (javathread)->get_thread_name(); \
147 len = strlen(name); \
148 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
149 (char *) name, len, \
150 java_lang_Thread::thread_id((javathread)->threadObj()), \
151 (uintptr_t) (javathread)->osthread()->thread_id(), \
152 java_lang_Thread::is_daemon((javathread)->threadObj())); \
153 }
154
155 #else // ndef DTRACE_ENABLED
156
157 #define DTRACE_THREAD_PROBE(probe, javathread)
158
159 #endif // ndef DTRACE_ENABLED
160
161 #ifndef USE_LIBRARY_BASED_TLS_ONLY
162 // Current thread is maintained as a thread-local variable
163 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
164 #endif
165 // Class hierarchy
166 // - Thread
167 // - VMThread
168 // - WatcherThread
169 // - ConcurrentMarkSweepThread
170 // - JavaThread
171 // - CompilerThread
172
173 // ======= Thread ========
174 // Support for forcing alignment of thread objects for biased locking
175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
176 if (UseBiasedLocking) {
177 const int alignment = markOopDesc::biased_lock_alignment;
178 size_t aligned_size = size + (alignment - sizeof(intptr_t));
179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
180 : AllocateHeap(aligned_size, flags, CURRENT_PC,
181 AllocFailStrategy::RETURN_NULL);
182 void* aligned_addr = align_up(real_malloc_addr, alignment);
183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
185 "JavaThread alignment code overflowed allocated storage");
186 if (aligned_addr != real_malloc_addr) {
187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
188 p2i(real_malloc_addr),
189 p2i(aligned_addr));
190 }
191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
192 return aligned_addr;
193 } else {
194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
196 }
197 }
198
199 void Thread::operator delete(void* p) {
200 if (UseBiasedLocking) {
201 FreeHeap(((Thread*) p)->_real_malloc_address);
202 } else {
203 FreeHeap(p);
204 }
205 }
206
207 void JavaThread::smr_delete() {
208 if (_on_thread_list) {
209 ThreadsSMRSupport::smr_delete(this);
210 } else {
211 delete this;
212 }
213 }
214
215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
216 // JavaThread
217
218
219 Thread::Thread() {
220 // stack and get_thread
221 set_stack_base(NULL);
222 set_stack_size(0);
223 set_self_raw_id(0);
224 set_lgrp_id(-1);
225 DEBUG_ONLY(clear_suspendible_thread();)
226
227 // allocated data structures
228 set_osthread(NULL);
229 set_resource_area(new (mtThread)ResourceArea());
230 DEBUG_ONLY(_current_resource_mark = NULL;)
231 set_handle_area(new (mtThread) HandleArea(NULL));
232 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
233 set_active_handles(NULL);
234 set_free_handle_block(NULL);
235 set_last_handle_mark(NULL);
236
237 // This initial value ==> never claimed.
238 _oops_do_parity = 0;
239 _threads_hazard_ptr = NULL;
240 _nested_threads_hazard_ptr = NULL;
241 _nested_threads_hazard_ptr_cnt = 0;
242
243 // the handle mark links itself to last_handle_mark
244 new HandleMark(this);
245
246 // plain initialization
247 debug_only(_owned_locks = NULL;)
248 debug_only(_allow_allocation_count = 0;)
249 NOT_PRODUCT(_allow_safepoint_count = 0;)
250 NOT_PRODUCT(_skip_gcalot = false;)
251 _jvmti_env_iteration_count = 0;
252 set_allocated_bytes(0);
253 _vm_operation_started_count = 0;
254 _vm_operation_completed_count = 0;
255 _current_pending_monitor = NULL;
256 _current_pending_monitor_is_from_java = true;
257 _current_waiting_monitor = NULL;
258 _num_nested_signal = 0;
259 omFreeList = NULL;
260 omFreeCount = 0;
261 omFreeProvision = 32;
262 omInUseList = NULL;
263 omInUseCount = 0;
264
265 #ifdef ASSERT
266 _visited_for_critical_count = false;
267 #endif
268
269 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
270 Monitor::_safepoint_check_sometimes);
271 _suspend_flags = 0;
272
273 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
274 _hashStateX = os::random();
275 _hashStateY = 842502087;
276 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
277 _hashStateW = 273326509;
278
279 _OnTrap = 0;
280 _schedctl = NULL;
281 _Stalled = 0;
282 _TypeTag = 0x2BAD;
283
284 // Many of the following fields are effectively final - immutable
285 // Note that nascent threads can't use the Native Monitor-Mutex
286 // construct until the _MutexEvent is initialized ...
287 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
288 // we might instead use a stack of ParkEvents that we could provision on-demand.
289 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
290 // and ::Release()
291 _ParkEvent = ParkEvent::Allocate(this);
292 _SleepEvent = ParkEvent::Allocate(this);
293 _MutexEvent = ParkEvent::Allocate(this);
294 _MuxEvent = ParkEvent::Allocate(this);
295
296 #ifdef CHECK_UNHANDLED_OOPS
297 if (CheckUnhandledOops) {
298 _unhandled_oops = new UnhandledOops(this);
299 }
300 #endif // CHECK_UNHANDLED_OOPS
301 #ifdef ASSERT
302 if (UseBiasedLocking) {
303 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
304 assert(this == _real_malloc_address ||
305 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
306 "bug in forced alignment of thread objects");
307 }
308 #endif // ASSERT
309 }
310
311 void Thread::initialize_thread_current() {
312 #ifndef USE_LIBRARY_BASED_TLS_ONLY
313 assert(_thr_current == NULL, "Thread::current already initialized");
314 _thr_current = this;
315 #endif
316 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
317 ThreadLocalStorage::set_thread(this);
318 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
319 }
320
321 void Thread::clear_thread_current() {
322 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
323 #ifndef USE_LIBRARY_BASED_TLS_ONLY
324 _thr_current = NULL;
325 #endif
326 ThreadLocalStorage::set_thread(NULL);
327 }
328
329 void Thread::record_stack_base_and_size() {
330 set_stack_base(os::current_stack_base());
331 set_stack_size(os::current_stack_size());
332 // CR 7190089: on Solaris, primordial thread's stack is adjusted
333 // in initialize_thread(). Without the adjustment, stack size is
334 // incorrect if stack is set to unlimited (ulimit -s unlimited).
335 // So far, only Solaris has real implementation of initialize_thread().
336 //
337 // set up any platform-specific state.
338 os::initialize_thread(this);
339
340 // Set stack limits after thread is initialized.
341 if (is_Java_thread()) {
342 ((JavaThread*) this)->set_stack_overflow_limit();
343 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
344 }
345 #if INCLUDE_NMT
346 // record thread's native stack, stack grows downward
347 MemTracker::record_thread_stack(stack_end(), stack_size());
348 #endif // INCLUDE_NMT
349 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
350 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
351 os::current_thread_id(), p2i(stack_base() - stack_size()),
352 p2i(stack_base()), stack_size()/1024);
353 }
354
355
356 Thread::~Thread() {
357 EVENT_THREAD_DESTRUCT(this);
358
359 // stack_base can be NULL if the thread is never started or exited before
360 // record_stack_base_and_size called. Although, we would like to ensure
361 // that all started threads do call record_stack_base_and_size(), there is
362 // not proper way to enforce that.
363 #if INCLUDE_NMT
364 if (_stack_base != NULL) {
365 MemTracker::release_thread_stack(stack_end(), stack_size());
366 #ifdef ASSERT
367 set_stack_base(NULL);
368 #endif
369 }
370 #endif // INCLUDE_NMT
371
372 // deallocate data structures
373 delete resource_area();
374 // since the handle marks are using the handle area, we have to deallocated the root
375 // handle mark before deallocating the thread's handle area,
376 assert(last_handle_mark() != NULL, "check we have an element");
377 delete last_handle_mark();
378 assert(last_handle_mark() == NULL, "check we have reached the end");
379
380 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
381 // We NULL out the fields for good hygiene.
382 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
383 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
384 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
385 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
386
387 delete handle_area();
388 delete metadata_handles();
389
390 // SR_handler uses this as a termination indicator -
391 // needs to happen before os::free_thread()
392 delete _SR_lock;
393 _SR_lock = NULL;
394
395 // osthread() can be NULL, if creation of thread failed.
396 if (osthread() != NULL) os::free_thread(osthread());
397
398 // clear Thread::current if thread is deleting itself.
399 // Needed to ensure JNI correctly detects non-attached threads.
400 if (this == Thread::current()) {
401 clear_thread_current();
402 }
403
404 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
405 }
406
407 // NOTE: dummy function for assertion purpose.
408 void Thread::run() {
409 ShouldNotReachHere();
410 }
411
412 #ifdef ASSERT
413 // A JavaThread is considered "dangling" if it is not the current
414 // thread, has been added the Threads list, the system is not at a
415 // safepoint and the Thread is not "protected".
416 //
417 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
418 assert(!thread->is_Java_thread() || Thread::current() == thread ||
419 !((JavaThread *) thread)->on_thread_list() ||
420 SafepointSynchronize::is_at_safepoint() ||
421 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
422 "possibility of dangling Thread pointer");
423 }
424 #endif
425
426 ThreadPriority Thread::get_priority(const Thread* const thread) {
427 ThreadPriority priority;
428 // Can return an error!
429 (void)os::get_priority(thread, priority);
430 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
431 return priority;
432 }
433
434 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
435 debug_only(check_for_dangling_thread_pointer(thread);)
436 // Can return an error!
437 (void)os::set_priority(thread, priority);
438 }
439
440
441 void Thread::start(Thread* thread) {
442 // Start is different from resume in that its safety is guaranteed by context or
443 // being called from a Java method synchronized on the Thread object.
444 if (!DisableStartThread) {
445 if (thread->is_Java_thread()) {
446 // Initialize the thread state to RUNNABLE before starting this thread.
447 // Can not set it after the thread started because we do not know the
448 // exact thread state at that time. It could be in MONITOR_WAIT or
449 // in SLEEPING or some other state.
450 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
451 java_lang_Thread::RUNNABLE);
452 }
453 os::start_thread(thread);
454 }
455 }
456
457 // Enqueue a VM_Operation to do the job for us - sometime later
458 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
459 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
460 VMThread::execute(vm_stop);
461 }
462
463
464 // Check if an external suspend request has completed (or has been
465 // cancelled). Returns true if the thread is externally suspended and
466 // false otherwise.
467 //
468 // The bits parameter returns information about the code path through
469 // the routine. Useful for debugging:
470 //
471 // set in is_ext_suspend_completed():
472 // 0x00000001 - routine was entered
473 // 0x00000010 - routine return false at end
474 // 0x00000100 - thread exited (return false)
475 // 0x00000200 - suspend request cancelled (return false)
476 // 0x00000400 - thread suspended (return true)
477 // 0x00001000 - thread is in a suspend equivalent state (return true)
478 // 0x00002000 - thread is native and walkable (return true)
479 // 0x00004000 - thread is native_trans and walkable (needed retry)
480 //
481 // set in wait_for_ext_suspend_completion():
482 // 0x00010000 - routine was entered
483 // 0x00020000 - suspend request cancelled before loop (return false)
484 // 0x00040000 - thread suspended before loop (return true)
485 // 0x00080000 - suspend request cancelled in loop (return false)
486 // 0x00100000 - thread suspended in loop (return true)
487 // 0x00200000 - suspend not completed during retry loop (return false)
488
489 // Helper class for tracing suspend wait debug bits.
490 //
491 // 0x00000100 indicates that the target thread exited before it could
492 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
493 // 0x00080000 each indicate a cancelled suspend request so they don't
494 // count as wait failures either.
495 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
496
497 class TraceSuspendDebugBits : public StackObj {
498 private:
499 JavaThread * jt;
500 bool is_wait;
501 bool called_by_wait; // meaningful when !is_wait
502 uint32_t * bits;
503
504 public:
505 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
506 uint32_t *_bits) {
507 jt = _jt;
508 is_wait = _is_wait;
509 called_by_wait = _called_by_wait;
510 bits = _bits;
511 }
512
513 ~TraceSuspendDebugBits() {
514 if (!is_wait) {
515 #if 1
516 // By default, don't trace bits for is_ext_suspend_completed() calls.
517 // That trace is very chatty.
518 return;
519 #else
520 if (!called_by_wait) {
521 // If tracing for is_ext_suspend_completed() is enabled, then only
522 // trace calls to it from wait_for_ext_suspend_completion()
523 return;
524 }
525 #endif
526 }
527
528 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
529 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
530 MutexLocker ml(Threads_lock); // needed for get_thread_name()
531 ResourceMark rm;
532
533 tty->print_cr(
534 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
535 jt->get_thread_name(), *bits);
536
537 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
538 }
539 }
540 }
541 };
542 #undef DEBUG_FALSE_BITS
543
544
545 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
546 uint32_t *bits) {
547 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
548
549 bool did_trans_retry = false; // only do thread_in_native_trans retry once
550 bool do_trans_retry; // flag to force the retry
551
552 *bits |= 0x00000001;
553
554 do {
555 do_trans_retry = false;
556
557 if (is_exiting()) {
558 // Thread is in the process of exiting. This is always checked
559 // first to reduce the risk of dereferencing a freed JavaThread.
560 *bits |= 0x00000100;
561 return false;
562 }
563
564 if (!is_external_suspend()) {
565 // Suspend request is cancelled. This is always checked before
566 // is_ext_suspended() to reduce the risk of a rogue resume
567 // confusing the thread that made the suspend request.
568 *bits |= 0x00000200;
569 return false;
570 }
571
572 if (is_ext_suspended()) {
573 // thread is suspended
574 *bits |= 0x00000400;
575 return true;
576 }
577
578 // Now that we no longer do hard suspends of threads running
579 // native code, the target thread can be changing thread state
580 // while we are in this routine:
581 //
582 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
583 //
584 // We save a copy of the thread state as observed at this moment
585 // and make our decision about suspend completeness based on the
586 // copy. This closes the race where the thread state is seen as
587 // _thread_in_native_trans in the if-thread_blocked check, but is
588 // seen as _thread_blocked in if-thread_in_native_trans check.
589 JavaThreadState save_state = thread_state();
590
591 if (save_state == _thread_blocked && is_suspend_equivalent()) {
592 // If the thread's state is _thread_blocked and this blocking
593 // condition is known to be equivalent to a suspend, then we can
594 // consider the thread to be externally suspended. This means that
595 // the code that sets _thread_blocked has been modified to do
596 // self-suspension if the blocking condition releases. We also
597 // used to check for CONDVAR_WAIT here, but that is now covered by
598 // the _thread_blocked with self-suspension check.
599 //
600 // Return true since we wouldn't be here unless there was still an
601 // external suspend request.
602 *bits |= 0x00001000;
603 return true;
604 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
605 // Threads running native code will self-suspend on native==>VM/Java
606 // transitions. If its stack is walkable (should always be the case
607 // unless this function is called before the actual java_suspend()
608 // call), then the wait is done.
609 *bits |= 0x00002000;
610 return true;
611 } else if (!called_by_wait && !did_trans_retry &&
612 save_state == _thread_in_native_trans &&
613 frame_anchor()->walkable()) {
614 // The thread is transitioning from thread_in_native to another
615 // thread state. check_safepoint_and_suspend_for_native_trans()
616 // will force the thread to self-suspend. If it hasn't gotten
617 // there yet we may have caught the thread in-between the native
618 // code check above and the self-suspend. Lucky us. If we were
619 // called by wait_for_ext_suspend_completion(), then it
620 // will be doing the retries so we don't have to.
621 //
622 // Since we use the saved thread state in the if-statement above,
623 // there is a chance that the thread has already transitioned to
624 // _thread_blocked by the time we get here. In that case, we will
625 // make a single unnecessary pass through the logic below. This
626 // doesn't hurt anything since we still do the trans retry.
627
628 *bits |= 0x00004000;
629
630 // Once the thread leaves thread_in_native_trans for another
631 // thread state, we break out of this retry loop. We shouldn't
632 // need this flag to prevent us from getting back here, but
633 // sometimes paranoia is good.
634 did_trans_retry = true;
635
636 // We wait for the thread to transition to a more usable state.
637 for (int i = 1; i <= SuspendRetryCount; i++) {
638 // We used to do an "os::yield_all(i)" call here with the intention
639 // that yielding would increase on each retry. However, the parameter
640 // is ignored on Linux which means the yield didn't scale up. Waiting
641 // on the SR_lock below provides a much more predictable scale up for
642 // the delay. It also provides a simple/direct point to check for any
643 // safepoint requests from the VMThread
644
645 // temporarily drops SR_lock while doing wait with safepoint check
646 // (if we're a JavaThread - the WatcherThread can also call this)
647 // and increase delay with each retry
648 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
649
650 // check the actual thread state instead of what we saved above
651 if (thread_state() != _thread_in_native_trans) {
652 // the thread has transitioned to another thread state so
653 // try all the checks (except this one) one more time.
654 do_trans_retry = true;
655 break;
656 }
657 } // end retry loop
658
659
660 }
661 } while (do_trans_retry);
662
663 *bits |= 0x00000010;
664 return false;
665 }
666
667 // Wait for an external suspend request to complete (or be cancelled).
668 // Returns true if the thread is externally suspended and false otherwise.
669 //
670 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
671 uint32_t *bits) {
672 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
673 false /* !called_by_wait */, bits);
674
675 // local flag copies to minimize SR_lock hold time
676 bool is_suspended;
677 bool pending;
678 uint32_t reset_bits;
679
680 // set a marker so is_ext_suspend_completed() knows we are the caller
681 *bits |= 0x00010000;
682
683 // We use reset_bits to reinitialize the bits value at the top of
684 // each retry loop. This allows the caller to make use of any
685 // unused bits for their own marking purposes.
686 reset_bits = *bits;
687
688 {
689 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
690 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
691 delay, bits);
692 pending = is_external_suspend();
693 }
694 // must release SR_lock to allow suspension to complete
695
696 if (!pending) {
697 // A cancelled suspend request is the only false return from
698 // is_ext_suspend_completed() that keeps us from entering the
699 // retry loop.
700 *bits |= 0x00020000;
701 return false;
702 }
703
704 if (is_suspended) {
705 *bits |= 0x00040000;
706 return true;
707 }
708
709 for (int i = 1; i <= retries; i++) {
710 *bits = reset_bits; // reinit to only track last retry
711
712 // We used to do an "os::yield_all(i)" call here with the intention
713 // that yielding would increase on each retry. However, the parameter
714 // is ignored on Linux which means the yield didn't scale up. Waiting
715 // on the SR_lock below provides a much more predictable scale up for
716 // the delay. It also provides a simple/direct point to check for any
717 // safepoint requests from the VMThread
718
719 {
720 MutexLocker ml(SR_lock());
721 // wait with safepoint check (if we're a JavaThread - the WatcherThread
722 // can also call this) and increase delay with each retry
723 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
724
725 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
726 delay, bits);
727
728 // It is possible for the external suspend request to be cancelled
729 // (by a resume) before the actual suspend operation is completed.
730 // Refresh our local copy to see if we still need to wait.
731 pending = is_external_suspend();
732 }
733
734 if (!pending) {
735 // A cancelled suspend request is the only false return from
736 // is_ext_suspend_completed() that keeps us from staying in the
737 // retry loop.
738 *bits |= 0x00080000;
739 return false;
740 }
741
742 if (is_suspended) {
743 *bits |= 0x00100000;
744 return true;
745 }
746 } // end retry loop
747
748 // thread did not suspend after all our retries
749 *bits |= 0x00200000;
750 return false;
751 }
752
753 // Called from API entry points which perform stack walking. If the
754 // associated JavaThread is the current thread, then wait_for_suspend
755 // is not used. Otherwise, it determines if we should wait for the
756 // "other" thread to complete external suspension. (NOTE: in future
757 // releases the suspension mechanism should be reimplemented so this
758 // is not necessary.)
759 //
760 bool
761 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
762 if (this != JavaThread::current()) {
763 // "other" threads require special handling.
764 if (wait_for_suspend) {
765 // We are allowed to wait for the external suspend to complete
766 // so give the other thread a chance to get suspended.
767 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
768 SuspendRetryDelay, bits)) {
769 // Didn't make it so let the caller know.
770 return false;
771 }
772 }
773 // We aren't allowed to wait for the external suspend to complete
774 // so if the other thread isn't externally suspended we need to
775 // let the caller know.
776 else if (!is_ext_suspend_completed_with_lock(bits)) {
777 return false;
778 }
779 }
780
781 return true;
782 }
783
784 #ifndef PRODUCT
785 void JavaThread::record_jump(address target, address instr, const char* file,
786 int line) {
787
788 // This should not need to be atomic as the only way for simultaneous
789 // updates is via interrupts. Even then this should be rare or non-existent
790 // and we don't care that much anyway.
791
792 int index = _jmp_ring_index;
793 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
794 _jmp_ring[index]._target = (intptr_t) target;
795 _jmp_ring[index]._instruction = (intptr_t) instr;
796 _jmp_ring[index]._file = file;
797 _jmp_ring[index]._line = line;
798 }
799 #endif // PRODUCT
800
801 void Thread::interrupt(Thread* thread) {
802 debug_only(check_for_dangling_thread_pointer(thread);)
803 os::interrupt(thread);
804 }
805
806 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
807 debug_only(check_for_dangling_thread_pointer(thread);)
808 // Note: If clear_interrupted==false, this simply fetches and
809 // returns the value of the field osthread()->interrupted().
810 return os::is_interrupted(thread, clear_interrupted);
811 }
812
813
814 // GC Support
815 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
816 int thread_parity = _oops_do_parity;
817 if (thread_parity != strong_roots_parity) {
818 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
819 if (res == thread_parity) {
820 return true;
821 } else {
822 guarantee(res == strong_roots_parity, "Or else what?");
823 return false;
824 }
825 }
826 return false;
827 }
828
829 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
830 active_handles()->oops_do(f);
831 // Do oop for ThreadShadow
832 f->do_oop((oop*)&_pending_exception);
833 handle_area()->oops_do(f);
834
835 if (MonitorInUseLists) {
836 // When using thread local monitor lists, we scan them here,
837 // and the remaining global monitors in ObjectSynchronizer::oops_do().
838 ObjectSynchronizer::thread_local_used_oops_do(this, f);
839 }
840 }
841
842 void Thread::metadata_handles_do(void f(Metadata*)) {
843 // Only walk the Handles in Thread.
844 if (metadata_handles() != NULL) {
845 for (int i = 0; i< metadata_handles()->length(); i++) {
846 f(metadata_handles()->at(i));
847 }
848 }
849 }
850
851 void Thread::print_on(outputStream* st) const {
852 // get_priority assumes osthread initialized
853 if (osthread() != NULL) {
854 int os_prio;
855 if (os::get_native_priority(this, &os_prio) == OS_OK) {
856 st->print("os_prio=%d ", os_prio);
857 }
858 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
859 ext().print_on(st);
860 osthread()->print_on(st);
861 }
862 if (_threads_hazard_ptr != NULL) {
863 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
864 }
865 if (_nested_threads_hazard_ptr != NULL) {
866 print_nested_threads_hazard_ptrs_on(st);
867 }
868 st->print(" ");
869 debug_only(if (WizardMode) print_owned_locks_on(st);)
870 }
871
872 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
873 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
874
875 if (EnableThreadSMRStatistics) {
876 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
877 }
878 st->print(", _nested_threads_hazard_ptrs=");
879 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
880 node = node->next()) {
881 if (node != _nested_threads_hazard_ptr) {
882 // First node does not need a comma-space separator.
883 st->print(", ");
884 }
885 st->print(INTPTR_FORMAT, p2i(node->t_list()));
886 }
887 }
888
889 // Thread::print_on_error() is called by fatal error handler. Don't use
890 // any lock or allocate memory.
891 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
892 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
893
894 if (is_VM_thread()) { st->print("VMThread"); }
895 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
896 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
897 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
898 else { st->print("Thread"); }
899
900 if (is_Named_thread()) {
901 st->print(" \"%s\"", name());
902 }
903
904 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
905 p2i(stack_end()), p2i(stack_base()));
906
907 if (osthread()) {
908 st->print(" [id=%d]", osthread()->thread_id());
909 }
910
911 if (_threads_hazard_ptr != NULL) {
912 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
913 }
914 if (_nested_threads_hazard_ptr != NULL) {
915 print_nested_threads_hazard_ptrs_on(st);
916 }
917 }
918
919 void Thread::print_value_on(outputStream* st) const {
920 if (is_Named_thread()) {
921 st->print(" \"%s\" ", name());
922 }
923 st->print(INTPTR_FORMAT, p2i(this)); // print address
924 }
925
926 #ifdef ASSERT
927 void Thread::print_owned_locks_on(outputStream* st) const {
928 Monitor *cur = _owned_locks;
929 if (cur == NULL) {
930 st->print(" (no locks) ");
931 } else {
932 st->print_cr(" Locks owned:");
933 while (cur) {
934 cur->print_on(st);
935 cur = cur->next();
936 }
937 }
938 }
939
940 static int ref_use_count = 0;
941
942 bool Thread::owns_locks_but_compiled_lock() const {
943 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
944 if (cur != Compile_lock) return true;
945 }
946 return false;
947 }
948
949
950 #endif
951
952 #ifndef PRODUCT
953
954 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
955 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
956 // no threads which allow_vm_block's are held
957 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
958 // Check if current thread is allowed to block at a safepoint
959 if (!(_allow_safepoint_count == 0)) {
960 fatal("Possible safepoint reached by thread that does not allow it");
961 }
962 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
963 fatal("LEAF method calling lock?");
964 }
965
966 #ifdef ASSERT
967 if (potential_vm_operation && is_Java_thread()
968 && !Universe::is_bootstrapping()) {
969 // Make sure we do not hold any locks that the VM thread also uses.
970 // This could potentially lead to deadlocks
971 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
972 // Threads_lock is special, since the safepoint synchronization will not start before this is
973 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
974 // since it is used to transfer control between JavaThreads and the VMThread
975 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
976 if ((cur->allow_vm_block() &&
977 cur != Threads_lock &&
978 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
979 cur != VMOperationRequest_lock &&
980 cur != VMOperationQueue_lock) ||
981 cur->rank() == Mutex::special) {
982 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
983 }
984 }
985 }
986
987 if (GCALotAtAllSafepoints) {
988 // We could enter a safepoint here and thus have a gc
989 InterfaceSupport::check_gc_alot();
990 }
991 #endif
992 }
993 #endif
994
995 bool Thread::is_in_stack(address adr) const {
996 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
997 address end = os::current_stack_pointer();
998 // Allow non Java threads to call this without stack_base
999 if (_stack_base == NULL) return true;
1000 if (stack_base() >= adr && adr >= end) return true;
1001
1002 return false;
1003 }
1004
1005 bool Thread::is_in_usable_stack(address adr) const {
1006 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1007 size_t usable_stack_size = _stack_size - stack_guard_size;
1008
1009 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1010 }
1011
1012
1013 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1014 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1015 // used for compilation in the future. If that change is made, the need for these methods
1016 // should be revisited, and they should be removed if possible.
1017
1018 bool Thread::is_lock_owned(address adr) const {
1019 return on_local_stack(adr);
1020 }
1021
1022 bool Thread::set_as_starting_thread() {
1023 // NOTE: this must be called inside the main thread.
1024 return os::create_main_thread((JavaThread*)this);
1025 }
1026
1027 static void initialize_class(Symbol* class_name, TRAPS) {
1028 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1029 InstanceKlass::cast(klass)->initialize(CHECK);
1030 }
1031
1032
1033 // Creates the initial ThreadGroup
1034 static Handle create_initial_thread_group(TRAPS) {
1035 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1036 InstanceKlass* ik = InstanceKlass::cast(k);
1037
1038 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1039 {
1040 JavaValue result(T_VOID);
1041 JavaCalls::call_special(&result,
1042 system_instance,
1043 ik,
1044 vmSymbols::object_initializer_name(),
1045 vmSymbols::void_method_signature(),
1046 CHECK_NH);
1047 }
1048 Universe::set_system_thread_group(system_instance());
1049
1050 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1051 {
1052 JavaValue result(T_VOID);
1053 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1054 JavaCalls::call_special(&result,
1055 main_instance,
1056 ik,
1057 vmSymbols::object_initializer_name(),
1058 vmSymbols::threadgroup_string_void_signature(),
1059 system_instance,
1060 string,
1061 CHECK_NH);
1062 }
1063 return main_instance;
1064 }
1065
1066 // Creates the initial Thread
1067 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1068 TRAPS) {
1069 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1070 InstanceKlass* ik = InstanceKlass::cast(k);
1071 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1072
1073 java_lang_Thread::set_thread(thread_oop(), thread);
1074 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1075 thread->set_threadObj(thread_oop());
1076
1077 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1078
1079 JavaValue result(T_VOID);
1080 JavaCalls::call_special(&result, thread_oop,
1081 ik,
1082 vmSymbols::object_initializer_name(),
1083 vmSymbols::threadgroup_string_void_signature(),
1084 thread_group,
1085 string,
1086 CHECK_NULL);
1087 return thread_oop();
1088 }
1089
1090 char java_runtime_name[128] = "";
1091 char java_runtime_version[128] = "";
1092
1093 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1094 static const char* get_java_runtime_name(TRAPS) {
1095 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1096 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1097 fieldDescriptor fd;
1098 bool found = k != NULL &&
1099 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1100 vmSymbols::string_signature(), &fd);
1101 if (found) {
1102 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1103 if (name_oop == NULL) {
1104 return NULL;
1105 }
1106 const char* name = java_lang_String::as_utf8_string(name_oop,
1107 java_runtime_name,
1108 sizeof(java_runtime_name));
1109 return name;
1110 } else {
1111 return NULL;
1112 }
1113 }
1114
1115 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1116 static const char* get_java_runtime_version(TRAPS) {
1117 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1118 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1119 fieldDescriptor fd;
1120 bool found = k != NULL &&
1121 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1122 vmSymbols::string_signature(), &fd);
1123 if (found) {
1124 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1125 if (name_oop == NULL) {
1126 return NULL;
1127 }
1128 const char* name = java_lang_String::as_utf8_string(name_oop,
1129 java_runtime_version,
1130 sizeof(java_runtime_version));
1131 return name;
1132 } else {
1133 return NULL;
1134 }
1135 }
1136
1137 // General purpose hook into Java code, run once when the VM is initialized.
1138 // The Java library method itself may be changed independently from the VM.
1139 static void call_postVMInitHook(TRAPS) {
1140 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1141 if (klass != NULL) {
1142 JavaValue result(T_VOID);
1143 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1144 vmSymbols::void_method_signature(),
1145 CHECK);
1146 }
1147 }
1148
1149 static void reset_vm_info_property(TRAPS) {
1150 // the vm info string
1151 ResourceMark rm(THREAD);
1152 const char *vm_info = VM_Version::vm_info_string();
1153
1154 // java.lang.System class
1155 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1156
1157 // setProperty arguments
1158 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1159 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1160
1161 // return value
1162 JavaValue r(T_OBJECT);
1163
1164 // public static String setProperty(String key, String value);
1165 JavaCalls::call_static(&r,
1166 klass,
1167 vmSymbols::setProperty_name(),
1168 vmSymbols::string_string_string_signature(),
1169 key_str,
1170 value_str,
1171 CHECK);
1172 }
1173
1174
1175 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1176 bool daemon, TRAPS) {
1177 assert(thread_group.not_null(), "thread group should be specified");
1178 assert(threadObj() == NULL, "should only create Java thread object once");
1179
1180 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1181 InstanceKlass* ik = InstanceKlass::cast(k);
1182 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1183
1184 java_lang_Thread::set_thread(thread_oop(), this);
1185 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1186 set_threadObj(thread_oop());
1187
1188 JavaValue result(T_VOID);
1189 if (thread_name != NULL) {
1190 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1191 // Thread gets assigned specified name and null target
1192 JavaCalls::call_special(&result,
1193 thread_oop,
1194 ik,
1195 vmSymbols::object_initializer_name(),
1196 vmSymbols::threadgroup_string_void_signature(),
1197 thread_group, // Argument 1
1198 name, // Argument 2
1199 THREAD);
1200 } else {
1201 // Thread gets assigned name "Thread-nnn" and null target
1202 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1203 JavaCalls::call_special(&result,
1204 thread_oop,
1205 ik,
1206 vmSymbols::object_initializer_name(),
1207 vmSymbols::threadgroup_runnable_void_signature(),
1208 thread_group, // Argument 1
1209 Handle(), // Argument 2
1210 THREAD);
1211 }
1212
1213
1214 if (daemon) {
1215 java_lang_Thread::set_daemon(thread_oop());
1216 }
1217
1218 if (HAS_PENDING_EXCEPTION) {
1219 return;
1220 }
1221
1222 Klass* group = SystemDictionary::ThreadGroup_klass();
1223 Handle threadObj(THREAD, this->threadObj());
1224
1225 JavaCalls::call_special(&result,
1226 thread_group,
1227 group,
1228 vmSymbols::add_method_name(),
1229 vmSymbols::thread_void_signature(),
1230 threadObj, // Arg 1
1231 THREAD);
1232 }
1233
1234 // NamedThread -- non-JavaThread subclasses with multiple
1235 // uniquely named instances should derive from this.
1236 NamedThread::NamedThread() : Thread() {
1237 _name = NULL;
1238 _processed_thread = NULL;
1239 _gc_id = GCId::undefined();
1240 }
1241
1242 NamedThread::~NamedThread() {
1243 if (_name != NULL) {
1244 FREE_C_HEAP_ARRAY(char, _name);
1245 _name = NULL;
1246 }
1247 }
1248
1249 void NamedThread::set_name(const char* format, ...) {
1250 guarantee(_name == NULL, "Only get to set name once.");
1251 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1252 guarantee(_name != NULL, "alloc failure");
1253 va_list ap;
1254 va_start(ap, format);
1255 jio_vsnprintf(_name, max_name_len, format, ap);
1256 va_end(ap);
1257 }
1258
1259 void NamedThread::initialize_named_thread() {
1260 set_native_thread_name(name());
1261 }
1262
1263 void NamedThread::print_on(outputStream* st) const {
1264 st->print("\"%s\" ", name());
1265 Thread::print_on(st);
1266 st->cr();
1267 }
1268
1269
1270 // ======= WatcherThread ========
1271
1272 // The watcher thread exists to simulate timer interrupts. It should
1273 // be replaced by an abstraction over whatever native support for
1274 // timer interrupts exists on the platform.
1275
1276 WatcherThread* WatcherThread::_watcher_thread = NULL;
1277 bool WatcherThread::_startable = false;
1278 volatile bool WatcherThread::_should_terminate = false;
1279
1280 WatcherThread::WatcherThread() : Thread() {
1281 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1282 if (os::create_thread(this, os::watcher_thread)) {
1283 _watcher_thread = this;
1284
1285 // Set the watcher thread to the highest OS priority which should not be
1286 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1287 // is created. The only normal thread using this priority is the reference
1288 // handler thread, which runs for very short intervals only.
1289 // If the VMThread's priority is not lower than the WatcherThread profiling
1290 // will be inaccurate.
1291 os::set_priority(this, MaxPriority);
1292 if (!DisableStartThread) {
1293 os::start_thread(this);
1294 }
1295 }
1296 }
1297
1298 int WatcherThread::sleep() const {
1299 // The WatcherThread does not participate in the safepoint protocol
1300 // for the PeriodicTask_lock because it is not a JavaThread.
1301 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1302
1303 if (_should_terminate) {
1304 // check for termination before we do any housekeeping or wait
1305 return 0; // we did not sleep.
1306 }
1307
1308 // remaining will be zero if there are no tasks,
1309 // causing the WatcherThread to sleep until a task is
1310 // enrolled
1311 int remaining = PeriodicTask::time_to_wait();
1312 int time_slept = 0;
1313
1314 // we expect this to timeout - we only ever get unparked when
1315 // we should terminate or when a new task has been enrolled
1316 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1317
1318 jlong time_before_loop = os::javaTimeNanos();
1319
1320 while (true) {
1321 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1322 remaining);
1323 jlong now = os::javaTimeNanos();
1324
1325 if (remaining == 0) {
1326 // if we didn't have any tasks we could have waited for a long time
1327 // consider the time_slept zero and reset time_before_loop
1328 time_slept = 0;
1329 time_before_loop = now;
1330 } else {
1331 // need to recalculate since we might have new tasks in _tasks
1332 time_slept = (int) ((now - time_before_loop) / 1000000);
1333 }
1334
1335 // Change to task list or spurious wakeup of some kind
1336 if (timedout || _should_terminate) {
1337 break;
1338 }
1339
1340 remaining = PeriodicTask::time_to_wait();
1341 if (remaining == 0) {
1342 // Last task was just disenrolled so loop around and wait until
1343 // another task gets enrolled
1344 continue;
1345 }
1346
1347 remaining -= time_slept;
1348 if (remaining <= 0) {
1349 break;
1350 }
1351 }
1352
1353 return time_slept;
1354 }
1355
1356 void WatcherThread::run() {
1357 assert(this == watcher_thread(), "just checking");
1358
1359 this->record_stack_base_and_size();
1360 this->set_native_thread_name(this->name());
1361 this->set_active_handles(JNIHandleBlock::allocate_block());
1362 while (true) {
1363 assert(watcher_thread() == Thread::current(), "thread consistency check");
1364 assert(watcher_thread() == this, "thread consistency check");
1365
1366 // Calculate how long it'll be until the next PeriodicTask work
1367 // should be done, and sleep that amount of time.
1368 int time_waited = sleep();
1369
1370 if (VMError::is_error_reported()) {
1371 // A fatal error has happened, the error handler(VMError::report_and_die)
1372 // should abort JVM after creating an error log file. However in some
1373 // rare cases, the error handler itself might deadlock. Here periodically
1374 // check for error reporting timeouts, and if it happens, just proceed to
1375 // abort the VM.
1376
1377 // This code is in WatcherThread because WatcherThread wakes up
1378 // periodically so the fatal error handler doesn't need to do anything;
1379 // also because the WatcherThread is less likely to crash than other
1380 // threads.
1381
1382 for (;;) {
1383 // Note: we use naked sleep in this loop because we want to avoid using
1384 // any kind of VM infrastructure which may be broken at this point.
1385 if (VMError::check_timeout()) {
1386 // We hit error reporting timeout. Error reporting was interrupted and
1387 // will be wrapping things up now (closing files etc). Give it some more
1388 // time, then quit the VM.
1389 os::naked_short_sleep(200);
1390 // Print a message to stderr.
1391 fdStream err(defaultStream::output_fd());
1392 err.print_raw_cr("# [ timer expired, abort... ]");
1393 // skip atexit/vm_exit/vm_abort hooks
1394 os::die();
1395 }
1396
1397 // Wait a second, then recheck for timeout.
1398 os::naked_short_sleep(999);
1399 }
1400 }
1401
1402 if (_should_terminate) {
1403 // check for termination before posting the next tick
1404 break;
1405 }
1406
1407 PeriodicTask::real_time_tick(time_waited);
1408 }
1409
1410 // Signal that it is terminated
1411 {
1412 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1413 _watcher_thread = NULL;
1414 Terminator_lock->notify();
1415 }
1416 }
1417
1418 void WatcherThread::start() {
1419 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1420
1421 if (watcher_thread() == NULL && _startable) {
1422 _should_terminate = false;
1423 // Create the single instance of WatcherThread
1424 new WatcherThread();
1425 }
1426 }
1427
1428 void WatcherThread::make_startable() {
1429 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1430 _startable = true;
1431 }
1432
1433 void WatcherThread::stop() {
1434 {
1435 // Follow normal safepoint aware lock enter protocol since the
1436 // WatcherThread is stopped by another JavaThread.
1437 MutexLocker ml(PeriodicTask_lock);
1438 _should_terminate = true;
1439
1440 WatcherThread* watcher = watcher_thread();
1441 if (watcher != NULL) {
1442 // unpark the WatcherThread so it can see that it should terminate
1443 watcher->unpark();
1444 }
1445 }
1446
1447 MutexLocker mu(Terminator_lock);
1448
1449 while (watcher_thread() != NULL) {
1450 // This wait should make safepoint checks, wait without a timeout,
1451 // and wait as a suspend-equivalent condition.
1452 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1453 Mutex::_as_suspend_equivalent_flag);
1454 }
1455 }
1456
1457 void WatcherThread::unpark() {
1458 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1459 PeriodicTask_lock->notify();
1460 }
1461
1462 void WatcherThread::print_on(outputStream* st) const {
1463 st->print("\"%s\" ", name());
1464 Thread::print_on(st);
1465 st->cr();
1466 }
1467
1468 // ======= JavaThread ========
1469
1470 #if INCLUDE_JVMCI
1471
1472 jlong* JavaThread::_jvmci_old_thread_counters;
1473
1474 bool jvmci_counters_include(JavaThread* thread) {
1475 oop threadObj = thread->threadObj();
1476 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1477 }
1478
1479 void JavaThread::collect_counters(typeArrayOop array) {
1480 if (JVMCICounterSize > 0) {
1481 MutexLocker tl(Threads_lock);
1482 JavaThreadIteratorWithHandle jtiwh;
1483 for (int i = 0; i < array->length(); i++) {
1484 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1485 }
1486 for (; JavaThread *tp = jtiwh.next(); ) {
1487 if (jvmci_counters_include(tp)) {
1488 for (int i = 0; i < array->length(); i++) {
1489 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1490 }
1491 }
1492 }
1493 }
1494 }
1495
1496 #endif // INCLUDE_JVMCI
1497
1498 // A JavaThread is a normal Java thread
1499
1500 void JavaThread::initialize() {
1501 // Initialize fields
1502
1503 set_saved_exception_pc(NULL);
1504 set_threadObj(NULL);
1505 _anchor.clear();
1506 set_entry_point(NULL);
1507 set_jni_functions(jni_functions());
1508 set_callee_target(NULL);
1509 set_vm_result(NULL);
1510 set_vm_result_2(NULL);
1511 set_vframe_array_head(NULL);
1512 set_vframe_array_last(NULL);
1513 set_deferred_locals(NULL);
1514 set_deopt_mark(NULL);
1515 set_deopt_compiled_method(NULL);
1516 clear_must_deopt_id();
1517 set_monitor_chunks(NULL);
1518 set_next(NULL);
1519 _on_thread_list = false;
1520 set_thread_state(_thread_new);
1521 _terminated = _not_terminated;
1522 _privileged_stack_top = NULL;
1523 _array_for_gc = NULL;
1524 _suspend_equivalent = false;
1525 _in_deopt_handler = 0;
1526 _doing_unsafe_access = false;
1527 _stack_guard_state = stack_guard_unused;
1528 #if INCLUDE_JVMCI
1529 _pending_monitorenter = false;
1530 _pending_deoptimization = -1;
1531 _pending_failed_speculation = NULL;
1532 _pending_transfer_to_interpreter = false;
1533 _adjusting_comp_level = false;
1534 _jvmci._alternate_call_target = NULL;
1535 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1536 if (JVMCICounterSize > 0) {
1537 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1538 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1539 } else {
1540 _jvmci_counters = NULL;
1541 }
1542 #endif // INCLUDE_JVMCI
1543 _reserved_stack_activation = NULL; // stack base not known yet
1544 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1545 _exception_pc = 0;
1546 _exception_handler_pc = 0;
1547 _is_method_handle_return = 0;
1548 _jvmti_thread_state= NULL;
1549 _should_post_on_exceptions_flag = JNI_FALSE;
1550 _jvmti_get_loaded_classes_closure = NULL;
1551 _interp_only_mode = 0;
1552 _special_runtime_exit_condition = _no_async_condition;
1553 _pending_async_exception = NULL;
1554 _thread_stat = NULL;
1555 _thread_stat = new ThreadStatistics();
1556 _blocked_on_compilation = false;
1557 _jni_active_critical = 0;
1558 _pending_jni_exception_check_fn = NULL;
1559 _do_not_unlock_if_synchronized = false;
1560 _cached_monitor_info = NULL;
1561 _parker = Parker::Allocate(this);
1562
1563 #ifndef PRODUCT
1564 _jmp_ring_index = 0;
1565 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1566 record_jump(NULL, NULL, NULL, 0);
1567 }
1568 #endif // PRODUCT
1569
1570 // Setup safepoint state info for this thread
1571 ThreadSafepointState::create(this);
1572
1573 debug_only(_java_call_counter = 0);
1574
1575 // JVMTI PopFrame support
1576 _popframe_condition = popframe_inactive;
1577 _popframe_preserved_args = NULL;
1578 _popframe_preserved_args_size = 0;
1579 _frames_to_pop_failed_realloc = 0;
1580
1581 if (SafepointMechanism::uses_thread_local_poll()) {
1582 SafepointMechanism::initialize_header(this);
1583 }
1584
1585 pd_initialize();
1586 }
1587
1588 #if INCLUDE_ALL_GCS
1589 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1590 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1591 #endif // INCLUDE_ALL_GCS
1592
1593 JavaThread::JavaThread(bool is_attaching_via_jni) :
1594 Thread()
1595 #if INCLUDE_ALL_GCS
1596 , _satb_mark_queue(&_satb_mark_queue_set),
1597 _dirty_card_queue(&_dirty_card_queue_set)
1598 #endif // INCLUDE_ALL_GCS
1599 {
1600 initialize();
1601 if (is_attaching_via_jni) {
1602 _jni_attach_state = _attaching_via_jni;
1603 } else {
1604 _jni_attach_state = _not_attaching_via_jni;
1605 }
1606 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1607 }
1608
1609 bool JavaThread::reguard_stack(address cur_sp) {
1610 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1611 && _stack_guard_state != stack_guard_reserved_disabled) {
1612 return true; // Stack already guarded or guard pages not needed.
1613 }
1614
1615 if (register_stack_overflow()) {
1616 // For those architectures which have separate register and
1617 // memory stacks, we must check the register stack to see if
1618 // it has overflowed.
1619 return false;
1620 }
1621
1622 // Java code never executes within the yellow zone: the latter is only
1623 // there to provoke an exception during stack banging. If java code
1624 // is executing there, either StackShadowPages should be larger, or
1625 // some exception code in c1, c2 or the interpreter isn't unwinding
1626 // when it should.
1627 guarantee(cur_sp > stack_reserved_zone_base(),
1628 "not enough space to reguard - increase StackShadowPages");
1629 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1630 enable_stack_yellow_reserved_zone();
1631 if (reserved_stack_activation() != stack_base()) {
1632 set_reserved_stack_activation(stack_base());
1633 }
1634 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1635 set_reserved_stack_activation(stack_base());
1636 enable_stack_reserved_zone();
1637 }
1638 return true;
1639 }
1640
1641 bool JavaThread::reguard_stack(void) {
1642 return reguard_stack(os::current_stack_pointer());
1643 }
1644
1645
1646 void JavaThread::block_if_vm_exited() {
1647 if (_terminated == _vm_exited) {
1648 // _vm_exited is set at safepoint, and Threads_lock is never released
1649 // we will block here forever
1650 Threads_lock->lock_without_safepoint_check();
1651 ShouldNotReachHere();
1652 }
1653 }
1654
1655
1656 // Remove this ifdef when C1 is ported to the compiler interface.
1657 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1658 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1659
1660 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1661 Thread()
1662 #if INCLUDE_ALL_GCS
1663 , _satb_mark_queue(&_satb_mark_queue_set),
1664 _dirty_card_queue(&_dirty_card_queue_set)
1665 #endif // INCLUDE_ALL_GCS
1666 {
1667 initialize();
1668 _jni_attach_state = _not_attaching_via_jni;
1669 set_entry_point(entry_point);
1670 // Create the native thread itself.
1671 // %note runtime_23
1672 os::ThreadType thr_type = os::java_thread;
1673 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1674 os::java_thread;
1675 os::create_thread(this, thr_type, stack_sz);
1676 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1677 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1678 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1679 // the exception consists of creating the exception object & initializing it, initialization
1680 // will leave the VM via a JavaCall and then all locks must be unlocked).
1681 //
1682 // The thread is still suspended when we reach here. Thread must be explicit started
1683 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1684 // by calling Threads:add. The reason why this is not done here, is because the thread
1685 // object must be fully initialized (take a look at JVM_Start)
1686 }
1687
1688 JavaThread::~JavaThread() {
1689
1690 // JSR166 -- return the parker to the free list
1691 Parker::Release(_parker);
1692 _parker = NULL;
1693
1694 // Free any remaining previous UnrollBlock
1695 vframeArray* old_array = vframe_array_last();
1696
1697 if (old_array != NULL) {
1698 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1699 old_array->set_unroll_block(NULL);
1700 delete old_info;
1701 delete old_array;
1702 }
1703
1704 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1705 if (deferred != NULL) {
1706 // This can only happen if thread is destroyed before deoptimization occurs.
1707 assert(deferred->length() != 0, "empty array!");
1708 do {
1709 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1710 deferred->remove_at(0);
1711 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1712 delete dlv;
1713 } while (deferred->length() != 0);
1714 delete deferred;
1715 }
1716
1717 // All Java related clean up happens in exit
1718 ThreadSafepointState::destroy(this);
1719 if (_thread_stat != NULL) delete _thread_stat;
1720
1721 #if INCLUDE_JVMCI
1722 if (JVMCICounterSize > 0) {
1723 if (jvmci_counters_include(this)) {
1724 for (int i = 0; i < JVMCICounterSize; i++) {
1725 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1726 }
1727 }
1728 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1729 }
1730 #endif // INCLUDE_JVMCI
1731 }
1732
1733
1734 // The first routine called by a new Java thread
1735 void JavaThread::run() {
1736 // initialize thread-local alloc buffer related fields
1737 this->initialize_tlab();
1738
1739 // used to test validity of stack trace backs
1740 this->record_base_of_stack_pointer();
1741
1742 // Record real stack base and size.
1743 this->record_stack_base_and_size();
1744
1745 this->create_stack_guard_pages();
1746
1747 this->cache_global_variables();
1748
1749 // Thread is now sufficient initialized to be handled by the safepoint code as being
1750 // in the VM. Change thread state from _thread_new to _thread_in_vm
1751 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1752
1753 assert(JavaThread::current() == this, "sanity check");
1754 assert(!Thread::current()->owns_locks(), "sanity check");
1755
1756 DTRACE_THREAD_PROBE(start, this);
1757
1758 // This operation might block. We call that after all safepoint checks for a new thread has
1759 // been completed.
1760 this->set_active_handles(JNIHandleBlock::allocate_block());
1761
1762 if (JvmtiExport::should_post_thread_life()) {
1763 JvmtiExport::post_thread_start(this);
1764 }
1765
1766 EventThreadStart event;
1767 if (event.should_commit()) {
1768 event.set_thread(THREAD_TRACE_ID(this));
1769 event.commit();
1770 }
1771
1772 // We call another function to do the rest so we are sure that the stack addresses used
1773 // from there will be lower than the stack base just computed
1774 thread_main_inner();
1775
1776 // Note, thread is no longer valid at this point!
1777 }
1778
1779
1780 void JavaThread::thread_main_inner() {
1781 assert(JavaThread::current() == this, "sanity check");
1782 assert(this->threadObj() != NULL, "just checking");
1783
1784 // Execute thread entry point unless this thread has a pending exception
1785 // or has been stopped before starting.
1786 // Note: Due to JVM_StopThread we can have pending exceptions already!
1787 if (!this->has_pending_exception() &&
1788 !java_lang_Thread::is_stillborn(this->threadObj())) {
1789 {
1790 ResourceMark rm(this);
1791 this->set_native_thread_name(this->get_thread_name());
1792 }
1793 HandleMark hm(this);
1794 this->entry_point()(this, this);
1795 }
1796
1797 DTRACE_THREAD_PROBE(stop, this);
1798
1799 this->exit(false);
1800 this->smr_delete();
1801 }
1802
1803
1804 static void ensure_join(JavaThread* thread) {
1805 // We do not need to grab the Threads_lock, since we are operating on ourself.
1806 Handle threadObj(thread, thread->threadObj());
1807 assert(threadObj.not_null(), "java thread object must exist");
1808 ObjectLocker lock(threadObj, thread);
1809 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1810 thread->clear_pending_exception();
1811 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1812 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1813 // Clear the native thread instance - this makes isAlive return false and allows the join()
1814 // to complete once we've done the notify_all below
1815 java_lang_Thread::set_thread(threadObj(), NULL);
1816 lock.notify_all(thread);
1817 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1818 thread->clear_pending_exception();
1819 }
1820
1821
1822 // For any new cleanup additions, please check to see if they need to be applied to
1823 // cleanup_failed_attach_current_thread as well.
1824 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1825 assert(this == JavaThread::current(), "thread consistency check");
1826
1827 elapsedTimer _timer_exit_phase1;
1828 elapsedTimer _timer_exit_phase2;
1829 elapsedTimer _timer_exit_phase3;
1830 elapsedTimer _timer_exit_phase4;
1831
1832 if (log_is_enabled(Debug, os, thread, timer)) {
1833 _timer_exit_phase1.start();
1834 }
1835
1836 HandleMark hm(this);
1837 Handle uncaught_exception(this, this->pending_exception());
1838 this->clear_pending_exception();
1839 Handle threadObj(this, this->threadObj());
1840 assert(threadObj.not_null(), "Java thread object should be created");
1841
1842 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1843 {
1844 EXCEPTION_MARK;
1845
1846 CLEAR_PENDING_EXCEPTION;
1847 }
1848 if (!destroy_vm) {
1849 if (uncaught_exception.not_null()) {
1850 EXCEPTION_MARK;
1851 // Call method Thread.dispatchUncaughtException().
1852 Klass* thread_klass = SystemDictionary::Thread_klass();
1853 JavaValue result(T_VOID);
1854 JavaCalls::call_virtual(&result,
1855 threadObj, thread_klass,
1856 vmSymbols::dispatchUncaughtException_name(),
1857 vmSymbols::throwable_void_signature(),
1858 uncaught_exception,
1859 THREAD);
1860 if (HAS_PENDING_EXCEPTION) {
1861 ResourceMark rm(this);
1862 jio_fprintf(defaultStream::error_stream(),
1863 "\nException: %s thrown from the UncaughtExceptionHandler"
1864 " in thread \"%s\"\n",
1865 pending_exception()->klass()->external_name(),
1866 get_thread_name());
1867 CLEAR_PENDING_EXCEPTION;
1868 }
1869 }
1870
1871 // Called before the java thread exit since we want to read info
1872 // from java_lang_Thread object
1873 EventThreadEnd event;
1874 if (event.should_commit()) {
1875 event.set_thread(THREAD_TRACE_ID(this));
1876 event.commit();
1877 }
1878
1879 // Call after last event on thread
1880 EVENT_THREAD_EXIT(this);
1881
1882 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1883 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1884 // is deprecated anyhow.
1885 if (!is_Compiler_thread()) {
1886 int count = 3;
1887 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1888 EXCEPTION_MARK;
1889 JavaValue result(T_VOID);
1890 Klass* thread_klass = SystemDictionary::Thread_klass();
1891 JavaCalls::call_virtual(&result,
1892 threadObj, thread_klass,
1893 vmSymbols::exit_method_name(),
1894 vmSymbols::void_method_signature(),
1895 THREAD);
1896 CLEAR_PENDING_EXCEPTION;
1897 }
1898 }
1899 // notify JVMTI
1900 if (JvmtiExport::should_post_thread_life()) {
1901 JvmtiExport::post_thread_end(this);
1902 }
1903
1904 // We have notified the agents that we are exiting, before we go on,
1905 // we must check for a pending external suspend request and honor it
1906 // in order to not surprise the thread that made the suspend request.
1907 while (true) {
1908 {
1909 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1910 if (!is_external_suspend()) {
1911 set_terminated(_thread_exiting);
1912 ThreadService::current_thread_exiting(this);
1913 break;
1914 }
1915 // Implied else:
1916 // Things get a little tricky here. We have a pending external
1917 // suspend request, but we are holding the SR_lock so we
1918 // can't just self-suspend. So we temporarily drop the lock
1919 // and then self-suspend.
1920 }
1921
1922 ThreadBlockInVM tbivm(this);
1923 java_suspend_self();
1924
1925 // We're done with this suspend request, but we have to loop around
1926 // and check again. Eventually we will get SR_lock without a pending
1927 // external suspend request and will be able to mark ourselves as
1928 // exiting.
1929 }
1930 // no more external suspends are allowed at this point
1931 } else {
1932 // before_exit() has already posted JVMTI THREAD_END events
1933 }
1934
1935 if (log_is_enabled(Debug, os, thread, timer)) {
1936 _timer_exit_phase1.stop();
1937 _timer_exit_phase2.start();
1938 }
1939 // Notify waiters on thread object. This has to be done after exit() is called
1940 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1941 // group should have the destroyed bit set before waiters are notified).
1942 ensure_join(this);
1943 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1944
1945 if (log_is_enabled(Debug, os, thread, timer)) {
1946 _timer_exit_phase2.stop();
1947 _timer_exit_phase3.start();
1948 }
1949 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1950 // held by this thread must be released. The spec does not distinguish
1951 // between JNI-acquired and regular Java monitors. We can only see
1952 // regular Java monitors here if monitor enter-exit matching is broken.
1953 //
1954 // Optionally release any monitors for regular JavaThread exits. This
1955 // is provided as a work around for any bugs in monitor enter-exit
1956 // matching. This can be expensive so it is not enabled by default.
1957 //
1958 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1959 // ObjectSynchronizer::release_monitors_owned_by_thread().
1960 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1961 // Sanity check even though JNI DetachCurrentThread() would have
1962 // returned JNI_ERR if there was a Java frame. JavaThread exit
1963 // should be done executing Java code by the time we get here.
1964 assert(!this->has_last_Java_frame(),
1965 "should not have a Java frame when detaching or exiting");
1966 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1967 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1968 }
1969
1970 // These things needs to be done while we are still a Java Thread. Make sure that thread
1971 // is in a consistent state, in case GC happens
1972 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1973
1974 if (active_handles() != NULL) {
1975 JNIHandleBlock* block = active_handles();
1976 set_active_handles(NULL);
1977 JNIHandleBlock::release_block(block);
1978 }
1979
1980 if (free_handle_block() != NULL) {
1981 JNIHandleBlock* block = free_handle_block();
1982 set_free_handle_block(NULL);
1983 JNIHandleBlock::release_block(block);
1984 }
1985
1986 // These have to be removed while this is still a valid thread.
1987 remove_stack_guard_pages();
1988
1989 if (UseTLAB) {
1990 tlab().make_parsable(true); // retire TLAB
1991 }
1992
1993 if (JvmtiEnv::environments_might_exist()) {
1994 JvmtiExport::cleanup_thread(this);
1995 }
1996
1997 // We must flush any deferred card marks and other various GC barrier
1998 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1999 // before removing a thread from the list of active threads.
2000 BarrierSet::barrier_set()->flush_deferred_barriers(this);
2001
2002 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2003 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2004 os::current_thread_id());
2005
2006 if (log_is_enabled(Debug, os, thread, timer)) {
2007 _timer_exit_phase3.stop();
2008 _timer_exit_phase4.start();
2009 }
2010 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2011 Threads::remove(this);
2012
2013 if (log_is_enabled(Debug, os, thread, timer)) {
2014 _timer_exit_phase4.stop();
2015 ResourceMark rm(this);
2016 log_debug(os, thread, timer)("name='%s'"
2017 ", exit-phase1=" JLONG_FORMAT
2018 ", exit-phase2=" JLONG_FORMAT
2019 ", exit-phase3=" JLONG_FORMAT
2020 ", exit-phase4=" JLONG_FORMAT,
2021 get_thread_name(),
2022 _timer_exit_phase1.milliseconds(),
2023 _timer_exit_phase2.milliseconds(),
2024 _timer_exit_phase3.milliseconds(),
2025 _timer_exit_phase4.milliseconds());
2026 }
2027 }
2028
2029 #if INCLUDE_ALL_GCS
2030 void JavaThread::initialize_queues() {
2031 assert(!SafepointSynchronize::is_at_safepoint(),
2032 "we should not be at a safepoint");
2033
2034 SATBMarkQueue& satb_queue = satb_mark_queue();
2035 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2036 // The SATB queue should have been constructed with its active
2037 // field set to false.
2038 assert(!satb_queue.is_active(), "SATB queue should not be active");
2039 assert(satb_queue.is_empty(), "SATB queue should be empty");
2040 // If we are creating the thread during a marking cycle, we should
2041 // set the active field of the SATB queue to true.
2042 if (satb_queue_set.is_active()) {
2043 satb_queue.set_active(true);
2044 }
2045
2046 DirtyCardQueue& dirty_queue = dirty_card_queue();
2047 // The dirty card queue should have been constructed with its
2048 // active field set to true.
2049 assert(dirty_queue.is_active(), "dirty card queue should be active");
2050 }
2051 #endif // INCLUDE_ALL_GCS
2052
2053 void JavaThread::cleanup_failed_attach_current_thread() {
2054 if (active_handles() != NULL) {
2055 JNIHandleBlock* block = active_handles();
2056 set_active_handles(NULL);
2057 JNIHandleBlock::release_block(block);
2058 }
2059
2060 if (free_handle_block() != NULL) {
2061 JNIHandleBlock* block = free_handle_block();
2062 set_free_handle_block(NULL);
2063 JNIHandleBlock::release_block(block);
2064 }
2065
2066 // These have to be removed while this is still a valid thread.
2067 remove_stack_guard_pages();
2068
2069 if (UseTLAB) {
2070 tlab().make_parsable(true); // retire TLAB, if any
2071 }
2072
2073 BarrierSet::barrier_set()->flush_deferred_barriers(this);
2074
2075 Threads::remove(this);
2076 this->smr_delete();
2077 }
2078
2079
2080
2081
2082 JavaThread* JavaThread::active() {
2083 Thread* thread = Thread::current();
2084 if (thread->is_Java_thread()) {
2085 return (JavaThread*) thread;
2086 } else {
2087 assert(thread->is_VM_thread(), "this must be a vm thread");
2088 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2089 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2090 assert(ret->is_Java_thread(), "must be a Java thread");
2091 return ret;
2092 }
2093 }
2094
2095 bool JavaThread::is_lock_owned(address adr) const {
2096 if (Thread::is_lock_owned(adr)) return true;
2097
2098 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2099 if (chunk->contains(adr)) return true;
2100 }
2101
2102 return false;
2103 }
2104
2105
2106 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2107 chunk->set_next(monitor_chunks());
2108 set_monitor_chunks(chunk);
2109 }
2110
2111 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2112 guarantee(monitor_chunks() != NULL, "must be non empty");
2113 if (monitor_chunks() == chunk) {
2114 set_monitor_chunks(chunk->next());
2115 } else {
2116 MonitorChunk* prev = monitor_chunks();
2117 while (prev->next() != chunk) prev = prev->next();
2118 prev->set_next(chunk->next());
2119 }
2120 }
2121
2122 // JVM support.
2123
2124 // Note: this function shouldn't block if it's called in
2125 // _thread_in_native_trans state (such as from
2126 // check_special_condition_for_native_trans()).
2127 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2128
2129 if (has_last_Java_frame() && has_async_condition()) {
2130 // If we are at a polling page safepoint (not a poll return)
2131 // then we must defer async exception because live registers
2132 // will be clobbered by the exception path. Poll return is
2133 // ok because the call we a returning from already collides
2134 // with exception handling registers and so there is no issue.
2135 // (The exception handling path kills call result registers but
2136 // this is ok since the exception kills the result anyway).
2137
2138 if (is_at_poll_safepoint()) {
2139 // if the code we are returning to has deoptimized we must defer
2140 // the exception otherwise live registers get clobbered on the
2141 // exception path before deoptimization is able to retrieve them.
2142 //
2143 RegisterMap map(this, false);
2144 frame caller_fr = last_frame().sender(&map);
2145 assert(caller_fr.is_compiled_frame(), "what?");
2146 if (caller_fr.is_deoptimized_frame()) {
2147 log_info(exceptions)("deferred async exception at compiled safepoint");
2148 return;
2149 }
2150 }
2151 }
2152
2153 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2154 if (condition == _no_async_condition) {
2155 // Conditions have changed since has_special_runtime_exit_condition()
2156 // was called:
2157 // - if we were here only because of an external suspend request,
2158 // then that was taken care of above (or cancelled) so we are done
2159 // - if we were here because of another async request, then it has
2160 // been cleared between the has_special_runtime_exit_condition()
2161 // and now so again we are done
2162 return;
2163 }
2164
2165 // Check for pending async. exception
2166 if (_pending_async_exception != NULL) {
2167 // Only overwrite an already pending exception, if it is not a threadDeath.
2168 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2169
2170 // We cannot call Exceptions::_throw(...) here because we cannot block
2171 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2172
2173 LogTarget(Info, exceptions) lt;
2174 if (lt.is_enabled()) {
2175 ResourceMark rm;
2176 LogStream ls(lt);
2177 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2178 if (has_last_Java_frame()) {
2179 frame f = last_frame();
2180 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2181 }
2182 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2183 }
2184 _pending_async_exception = NULL;
2185 clear_has_async_exception();
2186 }
2187 }
2188
2189 if (check_unsafe_error &&
2190 condition == _async_unsafe_access_error && !has_pending_exception()) {
2191 condition = _no_async_condition; // done
2192 switch (thread_state()) {
2193 case _thread_in_vm: {
2194 JavaThread* THREAD = this;
2195 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2196 }
2197 case _thread_in_native: {
2198 ThreadInVMfromNative tiv(this);
2199 JavaThread* THREAD = this;
2200 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2201 }
2202 case _thread_in_Java: {
2203 ThreadInVMfromJava tiv(this);
2204 JavaThread* THREAD = this;
2205 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2206 }
2207 default:
2208 ShouldNotReachHere();
2209 }
2210 }
2211
2212 assert(condition == _no_async_condition || has_pending_exception() ||
2213 (!check_unsafe_error && condition == _async_unsafe_access_error),
2214 "must have handled the async condition, if no exception");
2215 }
2216
2217 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2218 //
2219 // Check for pending external suspend. Internal suspend requests do
2220 // not use handle_special_runtime_exit_condition().
2221 // If JNIEnv proxies are allowed, don't self-suspend if the target
2222 // thread is not the current thread. In older versions of jdbx, jdbx
2223 // threads could call into the VM with another thread's JNIEnv so we
2224 // can be here operating on behalf of a suspended thread (4432884).
2225 bool do_self_suspend = is_external_suspend_with_lock();
2226 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2227 //
2228 // Because thread is external suspended the safepoint code will count
2229 // thread as at a safepoint. This can be odd because we can be here
2230 // as _thread_in_Java which would normally transition to _thread_blocked
2231 // at a safepoint. We would like to mark the thread as _thread_blocked
2232 // before calling java_suspend_self like all other callers of it but
2233 // we must then observe proper safepoint protocol. (We can't leave
2234 // _thread_blocked with a safepoint in progress). However we can be
2235 // here as _thread_in_native_trans so we can't use a normal transition
2236 // constructor/destructor pair because they assert on that type of
2237 // transition. We could do something like:
2238 //
2239 // JavaThreadState state = thread_state();
2240 // set_thread_state(_thread_in_vm);
2241 // {
2242 // ThreadBlockInVM tbivm(this);
2243 // java_suspend_self()
2244 // }
2245 // set_thread_state(_thread_in_vm_trans);
2246 // if (safepoint) block;
2247 // set_thread_state(state);
2248 //
2249 // but that is pretty messy. Instead we just go with the way the
2250 // code has worked before and note that this is the only path to
2251 // java_suspend_self that doesn't put the thread in _thread_blocked
2252 // mode.
2253
2254 frame_anchor()->make_walkable(this);
2255 java_suspend_self();
2256
2257 // We might be here for reasons in addition to the self-suspend request
2258 // so check for other async requests.
2259 }
2260
2261 if (check_asyncs) {
2262 check_and_handle_async_exceptions();
2263 }
2264 #if INCLUDE_TRACE
2265 if (is_trace_suspend()) {
2266 TRACE_SUSPEND_THREAD(this);
2267 }
2268 #endif
2269 }
2270
2271 void JavaThread::send_thread_stop(oop java_throwable) {
2272 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2273 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2274 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2275
2276 // Do not throw asynchronous exceptions against the compiler thread
2277 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2278 if (!can_call_java()) return;
2279
2280 {
2281 // Actually throw the Throwable against the target Thread - however
2282 // only if there is no thread death exception installed already.
2283 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2284 // If the topmost frame is a runtime stub, then we are calling into
2285 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2286 // must deoptimize the caller before continuing, as the compiled exception handler table
2287 // may not be valid
2288 if (has_last_Java_frame()) {
2289 frame f = last_frame();
2290 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2291 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2292 RegisterMap reg_map(this, UseBiasedLocking);
2293 frame compiled_frame = f.sender(®_map);
2294 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2295 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2296 }
2297 }
2298 }
2299
2300 // Set async. pending exception in thread.
2301 set_pending_async_exception(java_throwable);
2302
2303 if (log_is_enabled(Info, exceptions)) {
2304 ResourceMark rm;
2305 log_info(exceptions)("Pending Async. exception installed of type: %s",
2306 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2307 }
2308 // for AbortVMOnException flag
2309 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2310 }
2311 }
2312
2313
2314 // Interrupt thread so it will wake up from a potential wait()
2315 Thread::interrupt(this);
2316 }
2317
2318 // External suspension mechanism.
2319 //
2320 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2321 // to any VM_locks and it is at a transition
2322 // Self-suspension will happen on the transition out of the vm.
2323 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2324 //
2325 // Guarantees on return:
2326 // + Target thread will not execute any new bytecode (that's why we need to
2327 // force a safepoint)
2328 // + Target thread will not enter any new monitors
2329 //
2330 void JavaThread::java_suspend() {
2331 ThreadsListHandle tlh;
2332 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2333 return;
2334 }
2335
2336 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2337 if (!is_external_suspend()) {
2338 // a racing resume has cancelled us; bail out now
2339 return;
2340 }
2341
2342 // suspend is done
2343 uint32_t debug_bits = 0;
2344 // Warning: is_ext_suspend_completed() may temporarily drop the
2345 // SR_lock to allow the thread to reach a stable thread state if
2346 // it is currently in a transient thread state.
2347 if (is_ext_suspend_completed(false /* !called_by_wait */,
2348 SuspendRetryDelay, &debug_bits)) {
2349 return;
2350 }
2351 }
2352
2353 VM_ThreadSuspend vm_suspend;
2354 VMThread::execute(&vm_suspend);
2355 }
2356
2357 // Part II of external suspension.
2358 // A JavaThread self suspends when it detects a pending external suspend
2359 // request. This is usually on transitions. It is also done in places
2360 // where continuing to the next transition would surprise the caller,
2361 // e.g., monitor entry.
2362 //
2363 // Returns the number of times that the thread self-suspended.
2364 //
2365 // Note: DO NOT call java_suspend_self() when you just want to block current
2366 // thread. java_suspend_self() is the second stage of cooperative
2367 // suspension for external suspend requests and should only be used
2368 // to complete an external suspend request.
2369 //
2370 int JavaThread::java_suspend_self() {
2371 int ret = 0;
2372
2373 // we are in the process of exiting so don't suspend
2374 if (is_exiting()) {
2375 clear_external_suspend();
2376 return ret;
2377 }
2378
2379 assert(_anchor.walkable() ||
2380 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2381 "must have walkable stack");
2382
2383 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2384
2385 assert(!this->is_ext_suspended(),
2386 "a thread trying to self-suspend should not already be suspended");
2387
2388 if (this->is_suspend_equivalent()) {
2389 // If we are self-suspending as a result of the lifting of a
2390 // suspend equivalent condition, then the suspend_equivalent
2391 // flag is not cleared until we set the ext_suspended flag so
2392 // that wait_for_ext_suspend_completion() returns consistent
2393 // results.
2394 this->clear_suspend_equivalent();
2395 }
2396
2397 // A racing resume may have cancelled us before we grabbed SR_lock
2398 // above. Or another external suspend request could be waiting for us
2399 // by the time we return from SR_lock()->wait(). The thread
2400 // that requested the suspension may already be trying to walk our
2401 // stack and if we return now, we can change the stack out from under
2402 // it. This would be a "bad thing (TM)" and cause the stack walker
2403 // to crash. We stay self-suspended until there are no more pending
2404 // external suspend requests.
2405 while (is_external_suspend()) {
2406 ret++;
2407 this->set_ext_suspended();
2408
2409 // _ext_suspended flag is cleared by java_resume()
2410 while (is_ext_suspended()) {
2411 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2412 }
2413 }
2414
2415 return ret;
2416 }
2417
2418 #ifdef ASSERT
2419 // verify the JavaThread has not yet been published in the Threads::list, and
2420 // hence doesn't need protection from concurrent access at this stage
2421 void JavaThread::verify_not_published() {
2422 ThreadsListHandle tlh;
2423 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2424 }
2425 #endif
2426
2427 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2428 // progress or when _suspend_flags is non-zero.
2429 // Current thread needs to self-suspend if there is a suspend request and/or
2430 // block if a safepoint is in progress.
2431 // Async exception ISN'T checked.
2432 // Note only the ThreadInVMfromNative transition can call this function
2433 // directly and when thread state is _thread_in_native_trans
2434 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2435 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2436
2437 JavaThread *curJT = JavaThread::current();
2438 bool do_self_suspend = thread->is_external_suspend();
2439
2440 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2441
2442 // If JNIEnv proxies are allowed, don't self-suspend if the target
2443 // thread is not the current thread. In older versions of jdbx, jdbx
2444 // threads could call into the VM with another thread's JNIEnv so we
2445 // can be here operating on behalf of a suspended thread (4432884).
2446 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2447 JavaThreadState state = thread->thread_state();
2448
2449 // We mark this thread_blocked state as a suspend-equivalent so
2450 // that a caller to is_ext_suspend_completed() won't be confused.
2451 // The suspend-equivalent state is cleared by java_suspend_self().
2452 thread->set_suspend_equivalent();
2453
2454 // If the safepoint code sees the _thread_in_native_trans state, it will
2455 // wait until the thread changes to other thread state. There is no
2456 // guarantee on how soon we can obtain the SR_lock and complete the
2457 // self-suspend request. It would be a bad idea to let safepoint wait for
2458 // too long. Temporarily change the state to _thread_blocked to
2459 // let the VM thread know that this thread is ready for GC. The problem
2460 // of changing thread state is that safepoint could happen just after
2461 // java_suspend_self() returns after being resumed, and VM thread will
2462 // see the _thread_blocked state. We must check for safepoint
2463 // after restoring the state and make sure we won't leave while a safepoint
2464 // is in progress.
2465 thread->set_thread_state(_thread_blocked);
2466 thread->java_suspend_self();
2467 thread->set_thread_state(state);
2468
2469 InterfaceSupport::serialize_thread_state_with_handler(thread);
2470 }
2471
2472 SafepointMechanism::block_if_requested(curJT);
2473
2474 if (thread->is_deopt_suspend()) {
2475 thread->clear_deopt_suspend();
2476 RegisterMap map(thread, false);
2477 frame f = thread->last_frame();
2478 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2479 f = f.sender(&map);
2480 }
2481 if (f.id() == thread->must_deopt_id()) {
2482 thread->clear_must_deopt_id();
2483 f.deoptimize(thread);
2484 } else {
2485 fatal("missed deoptimization!");
2486 }
2487 }
2488 #if INCLUDE_TRACE
2489 if (thread->is_trace_suspend()) {
2490 TRACE_SUSPEND_THREAD(thread);
2491 }
2492 #endif
2493 }
2494
2495 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2496 // progress or when _suspend_flags is non-zero.
2497 // Current thread needs to self-suspend if there is a suspend request and/or
2498 // block if a safepoint is in progress.
2499 // Also check for pending async exception (not including unsafe access error).
2500 // Note only the native==>VM/Java barriers can call this function and when
2501 // thread state is _thread_in_native_trans.
2502 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2503 check_safepoint_and_suspend_for_native_trans(thread);
2504
2505 if (thread->has_async_exception()) {
2506 // We are in _thread_in_native_trans state, don't handle unsafe
2507 // access error since that may block.
2508 thread->check_and_handle_async_exceptions(false);
2509 }
2510 }
2511
2512 // This is a variant of the normal
2513 // check_special_condition_for_native_trans with slightly different
2514 // semantics for use by critical native wrappers. It does all the
2515 // normal checks but also performs the transition back into
2516 // thread_in_Java state. This is required so that critical natives
2517 // can potentially block and perform a GC if they are the last thread
2518 // exiting the GCLocker.
2519 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2520 check_special_condition_for_native_trans(thread);
2521
2522 // Finish the transition
2523 thread->set_thread_state(_thread_in_Java);
2524
2525 if (thread->do_critical_native_unlock()) {
2526 ThreadInVMfromJavaNoAsyncException tiv(thread);
2527 GCLocker::unlock_critical(thread);
2528 thread->clear_critical_native_unlock();
2529 }
2530 }
2531
2532 // We need to guarantee the Threads_lock here, since resumes are not
2533 // allowed during safepoint synchronization
2534 // Can only resume from an external suspension
2535 void JavaThread::java_resume() {
2536 assert_locked_or_safepoint(Threads_lock);
2537
2538 // Sanity check: thread is gone, has started exiting or the thread
2539 // was not externally suspended.
2540 ThreadsListHandle tlh;
2541 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2542 return;
2543 }
2544
2545 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2546
2547 clear_external_suspend();
2548
2549 if (is_ext_suspended()) {
2550 clear_ext_suspended();
2551 SR_lock()->notify_all();
2552 }
2553 }
2554
2555 size_t JavaThread::_stack_red_zone_size = 0;
2556 size_t JavaThread::_stack_yellow_zone_size = 0;
2557 size_t JavaThread::_stack_reserved_zone_size = 0;
2558 size_t JavaThread::_stack_shadow_zone_size = 0;
2559
2560 void JavaThread::create_stack_guard_pages() {
2561 if (!os::uses_stack_guard_pages() ||
2562 _stack_guard_state != stack_guard_unused ||
2563 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2564 log_info(os, thread)("Stack guard page creation for thread "
2565 UINTX_FORMAT " disabled", os::current_thread_id());
2566 return;
2567 }
2568 address low_addr = stack_end();
2569 size_t len = stack_guard_zone_size();
2570
2571 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2572 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2573
2574 int must_commit = os::must_commit_stack_guard_pages();
2575 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2576
2577 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2578 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2579 return;
2580 }
2581
2582 if (os::guard_memory((char *) low_addr, len)) {
2583 _stack_guard_state = stack_guard_enabled;
2584 } else {
2585 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2586 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2587 if (os::uncommit_memory((char *) low_addr, len)) {
2588 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2589 }
2590 return;
2591 }
2592
2593 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2594 PTR_FORMAT "-" PTR_FORMAT ".",
2595 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2596 }
2597
2598 void JavaThread::remove_stack_guard_pages() {
2599 assert(Thread::current() == this, "from different thread");
2600 if (_stack_guard_state == stack_guard_unused) return;
2601 address low_addr = stack_end();
2602 size_t len = stack_guard_zone_size();
2603
2604 if (os::must_commit_stack_guard_pages()) {
2605 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2606 _stack_guard_state = stack_guard_unused;
2607 } else {
2608 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2609 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2610 return;
2611 }
2612 } else {
2613 if (_stack_guard_state == stack_guard_unused) return;
2614 if (os::unguard_memory((char *) low_addr, len)) {
2615 _stack_guard_state = stack_guard_unused;
2616 } else {
2617 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2618 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2619 return;
2620 }
2621 }
2622
2623 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2624 PTR_FORMAT "-" PTR_FORMAT ".",
2625 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2626 }
2627
2628 void JavaThread::enable_stack_reserved_zone() {
2629 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2630 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2631
2632 // The base notation is from the stack's point of view, growing downward.
2633 // We need to adjust it to work correctly with guard_memory()
2634 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2635
2636 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2637 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2638
2639 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2640 _stack_guard_state = stack_guard_enabled;
2641 } else {
2642 warning("Attempt to guard stack reserved zone failed.");
2643 }
2644 enable_register_stack_guard();
2645 }
2646
2647 void JavaThread::disable_stack_reserved_zone() {
2648 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2649 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2650
2651 // Simply return if called for a thread that does not use guard pages.
2652 if (_stack_guard_state == stack_guard_unused) return;
2653
2654 // The base notation is from the stack's point of view, growing downward.
2655 // We need to adjust it to work correctly with guard_memory()
2656 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2657
2658 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2659 _stack_guard_state = stack_guard_reserved_disabled;
2660 } else {
2661 warning("Attempt to unguard stack reserved zone failed.");
2662 }
2663 disable_register_stack_guard();
2664 }
2665
2666 void JavaThread::enable_stack_yellow_reserved_zone() {
2667 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2668 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2669
2670 // The base notation is from the stacks point of view, growing downward.
2671 // We need to adjust it to work correctly with guard_memory()
2672 address base = stack_red_zone_base();
2673
2674 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2675 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2676
2677 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2678 _stack_guard_state = stack_guard_enabled;
2679 } else {
2680 warning("Attempt to guard stack yellow zone failed.");
2681 }
2682 enable_register_stack_guard();
2683 }
2684
2685 void JavaThread::disable_stack_yellow_reserved_zone() {
2686 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2687 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2688
2689 // Simply return if called for a thread that does not use guard pages.
2690 if (_stack_guard_state == stack_guard_unused) return;
2691
2692 // The base notation is from the stacks point of view, growing downward.
2693 // We need to adjust it to work correctly with guard_memory()
2694 address base = stack_red_zone_base();
2695
2696 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2697 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2698 } else {
2699 warning("Attempt to unguard stack yellow zone failed.");
2700 }
2701 disable_register_stack_guard();
2702 }
2703
2704 void JavaThread::enable_stack_red_zone() {
2705 // The base notation is from the stacks point of view, growing downward.
2706 // We need to adjust it to work correctly with guard_memory()
2707 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2708 address base = stack_red_zone_base() - stack_red_zone_size();
2709
2710 guarantee(base < stack_base(), "Error calculating stack red zone");
2711 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2712
2713 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2714 warning("Attempt to guard stack red zone failed.");
2715 }
2716 }
2717
2718 void JavaThread::disable_stack_red_zone() {
2719 // The base notation is from the stacks point of view, growing downward.
2720 // We need to adjust it to work correctly with guard_memory()
2721 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2722 address base = stack_red_zone_base() - stack_red_zone_size();
2723 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2724 warning("Attempt to unguard stack red zone failed.");
2725 }
2726 }
2727
2728 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2729 // ignore is there is no stack
2730 if (!has_last_Java_frame()) return;
2731 // traverse the stack frames. Starts from top frame.
2732 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2733 frame* fr = fst.current();
2734 f(fr, fst.register_map());
2735 }
2736 }
2737
2738
2739 #ifndef PRODUCT
2740 // Deoptimization
2741 // Function for testing deoptimization
2742 void JavaThread::deoptimize() {
2743 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2744 StackFrameStream fst(this, UseBiasedLocking);
2745 bool deopt = false; // Dump stack only if a deopt actually happens.
2746 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2747 // Iterate over all frames in the thread and deoptimize
2748 for (; !fst.is_done(); fst.next()) {
2749 if (fst.current()->can_be_deoptimized()) {
2750
2751 if (only_at) {
2752 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2753 // consists of comma or carriage return separated numbers so
2754 // search for the current bci in that string.
2755 address pc = fst.current()->pc();
2756 nmethod* nm = (nmethod*) fst.current()->cb();
2757 ScopeDesc* sd = nm->scope_desc_at(pc);
2758 char buffer[8];
2759 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2760 size_t len = strlen(buffer);
2761 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2762 while (found != NULL) {
2763 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2764 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2765 // Check that the bci found is bracketed by terminators.
2766 break;
2767 }
2768 found = strstr(found + 1, buffer);
2769 }
2770 if (!found) {
2771 continue;
2772 }
2773 }
2774
2775 if (DebugDeoptimization && !deopt) {
2776 deopt = true; // One-time only print before deopt
2777 tty->print_cr("[BEFORE Deoptimization]");
2778 trace_frames();
2779 trace_stack();
2780 }
2781 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2782 }
2783 }
2784
2785 if (DebugDeoptimization && deopt) {
2786 tty->print_cr("[AFTER Deoptimization]");
2787 trace_frames();
2788 }
2789 }
2790
2791
2792 // Make zombies
2793 void JavaThread::make_zombies() {
2794 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2795 if (fst.current()->can_be_deoptimized()) {
2796 // it is a Java nmethod
2797 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2798 nm->make_not_entrant();
2799 }
2800 }
2801 }
2802 #endif // PRODUCT
2803
2804
2805 void JavaThread::deoptimized_wrt_marked_nmethods() {
2806 if (!has_last_Java_frame()) return;
2807 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2808 StackFrameStream fst(this, UseBiasedLocking);
2809 for (; !fst.is_done(); fst.next()) {
2810 if (fst.current()->should_be_deoptimized()) {
2811 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2812 }
2813 }
2814 }
2815
2816
2817 // If the caller is a NamedThread, then remember, in the current scope,
2818 // the given JavaThread in its _processed_thread field.
2819 class RememberProcessedThread: public StackObj {
2820 NamedThread* _cur_thr;
2821 public:
2822 RememberProcessedThread(JavaThread* jthr) {
2823 Thread* thread = Thread::current();
2824 if (thread->is_Named_thread()) {
2825 _cur_thr = (NamedThread *)thread;
2826 _cur_thr->set_processed_thread(jthr);
2827 } else {
2828 _cur_thr = NULL;
2829 }
2830 }
2831
2832 ~RememberProcessedThread() {
2833 if (_cur_thr) {
2834 _cur_thr->set_processed_thread(NULL);
2835 }
2836 }
2837 };
2838
2839 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2840 // Verify that the deferred card marks have been flushed.
2841 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2842
2843 // Traverse the GCHandles
2844 Thread::oops_do(f, cf);
2845
2846 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2847
2848 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2849 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2850
2851 if (has_last_Java_frame()) {
2852 // Record JavaThread to GC thread
2853 RememberProcessedThread rpt(this);
2854
2855 // Traverse the privileged stack
2856 if (_privileged_stack_top != NULL) {
2857 _privileged_stack_top->oops_do(f);
2858 }
2859
2860 // traverse the registered growable array
2861 if (_array_for_gc != NULL) {
2862 for (int index = 0; index < _array_for_gc->length(); index++) {
2863 f->do_oop(_array_for_gc->adr_at(index));
2864 }
2865 }
2866
2867 // Traverse the monitor chunks
2868 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2869 chunk->oops_do(f);
2870 }
2871
2872 // Traverse the execution stack
2873 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2874 fst.current()->oops_do(f, cf, fst.register_map());
2875 }
2876 }
2877
2878 // callee_target is never live across a gc point so NULL it here should
2879 // it still contain a methdOop.
2880
2881 set_callee_target(NULL);
2882
2883 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2884 // If we have deferred set_locals there might be oops waiting to be
2885 // written
2886 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2887 if (list != NULL) {
2888 for (int i = 0; i < list->length(); i++) {
2889 list->at(i)->oops_do(f);
2890 }
2891 }
2892
2893 // Traverse instance variables at the end since the GC may be moving things
2894 // around using this function
2895 f->do_oop((oop*) &_threadObj);
2896 f->do_oop((oop*) &_vm_result);
2897 f->do_oop((oop*) &_exception_oop);
2898 f->do_oop((oop*) &_pending_async_exception);
2899
2900 if (jvmti_thread_state() != NULL) {
2901 jvmti_thread_state()->oops_do(f);
2902 }
2903 }
2904
2905 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2906 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2907 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2908
2909 if (has_last_Java_frame()) {
2910 // Traverse the execution stack
2911 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2912 fst.current()->nmethods_do(cf);
2913 }
2914 }
2915 }
2916
2917 void JavaThread::metadata_do(void f(Metadata*)) {
2918 if (has_last_Java_frame()) {
2919 // Traverse the execution stack to call f() on the methods in the stack
2920 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2921 fst.current()->metadata_do(f);
2922 }
2923 } else if (is_Compiler_thread()) {
2924 // need to walk ciMetadata in current compile tasks to keep alive.
2925 CompilerThread* ct = (CompilerThread*)this;
2926 if (ct->env() != NULL) {
2927 ct->env()->metadata_do(f);
2928 }
2929 CompileTask* task = ct->task();
2930 if (task != NULL) {
2931 task->metadata_do(f);
2932 }
2933 }
2934 }
2935
2936 // Printing
2937 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2938 switch (_thread_state) {
2939 case _thread_uninitialized: return "_thread_uninitialized";
2940 case _thread_new: return "_thread_new";
2941 case _thread_new_trans: return "_thread_new_trans";
2942 case _thread_in_native: return "_thread_in_native";
2943 case _thread_in_native_trans: return "_thread_in_native_trans";
2944 case _thread_in_vm: return "_thread_in_vm";
2945 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2946 case _thread_in_Java: return "_thread_in_Java";
2947 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2948 case _thread_blocked: return "_thread_blocked";
2949 case _thread_blocked_trans: return "_thread_blocked_trans";
2950 default: return "unknown thread state";
2951 }
2952 }
2953
2954 #ifndef PRODUCT
2955 void JavaThread::print_thread_state_on(outputStream *st) const {
2956 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2957 };
2958 void JavaThread::print_thread_state() const {
2959 print_thread_state_on(tty);
2960 }
2961 #endif // PRODUCT
2962
2963 // Called by Threads::print() for VM_PrintThreads operation
2964 void JavaThread::print_on(outputStream *st) const {
2965 st->print_raw("\"");
2966 st->print_raw(get_thread_name());
2967 st->print_raw("\" ");
2968 oop thread_oop = threadObj();
2969 if (thread_oop != NULL) {
2970 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2971 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2972 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2973 }
2974 Thread::print_on(st);
2975 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2976 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2977 if (thread_oop != NULL) {
2978 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2979 }
2980 #ifndef PRODUCT
2981 print_thread_state_on(st);
2982 _safepoint_state->print_on(st);
2983 #endif // PRODUCT
2984 if (is_Compiler_thread()) {
2985 CompileTask *task = ((CompilerThread*)this)->task();
2986 if (task != NULL) {
2987 st->print(" Compiling: ");
2988 task->print(st, NULL, true, false);
2989 } else {
2990 st->print(" No compile task");
2991 }
2992 st->cr();
2993 }
2994 }
2995
2996 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2997 st->print("%s", get_thread_name_string(buf, buflen));
2998 }
2999
3000 // Called by fatal error handler. The difference between this and
3001 // JavaThread::print() is that we can't grab lock or allocate memory.
3002 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3003 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3004 oop thread_obj = threadObj();
3005 if (thread_obj != NULL) {
3006 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3007 }
3008 st->print(" [");
3009 st->print("%s", _get_thread_state_name(_thread_state));
3010 if (osthread()) {
3011 st->print(", id=%d", osthread()->thread_id());
3012 }
3013 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3014 p2i(stack_end()), p2i(stack_base()));
3015 st->print("]");
3016
3017 if (_threads_hazard_ptr != NULL) {
3018 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3019 }
3020 if (_nested_threads_hazard_ptr != NULL) {
3021 print_nested_threads_hazard_ptrs_on(st);
3022 }
3023 return;
3024 }
3025
3026 // Verification
3027
3028 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3029
3030 void JavaThread::verify() {
3031 // Verify oops in the thread.
3032 oops_do(&VerifyOopClosure::verify_oop, NULL);
3033
3034 // Verify the stack frames.
3035 frames_do(frame_verify);
3036 }
3037
3038 // CR 6300358 (sub-CR 2137150)
3039 // Most callers of this method assume that it can't return NULL but a
3040 // thread may not have a name whilst it is in the process of attaching to
3041 // the VM - see CR 6412693, and there are places where a JavaThread can be
3042 // seen prior to having it's threadObj set (eg JNI attaching threads and
3043 // if vm exit occurs during initialization). These cases can all be accounted
3044 // for such that this method never returns NULL.
3045 const char* JavaThread::get_thread_name() const {
3046 #ifdef ASSERT
3047 // early safepoints can hit while current thread does not yet have TLS
3048 if (!SafepointSynchronize::is_at_safepoint()) {
3049 Thread *cur = Thread::current();
3050 if (!(cur->is_Java_thread() && cur == this)) {
3051 // Current JavaThreads are allowed to get their own name without
3052 // the Threads_lock.
3053 assert_locked_or_safepoint(Threads_lock);
3054 }
3055 }
3056 #endif // ASSERT
3057 return get_thread_name_string();
3058 }
3059
3060 // Returns a non-NULL representation of this thread's name, or a suitable
3061 // descriptive string if there is no set name
3062 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3063 const char* name_str;
3064 oop thread_obj = threadObj();
3065 if (thread_obj != NULL) {
3066 oop name = java_lang_Thread::name(thread_obj);
3067 if (name != NULL) {
3068 if (buf == NULL) {
3069 name_str = java_lang_String::as_utf8_string(name);
3070 } else {
3071 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3072 }
3073 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3074 name_str = "<no-name - thread is attaching>";
3075 } else {
3076 name_str = Thread::name();
3077 }
3078 } else {
3079 name_str = Thread::name();
3080 }
3081 assert(name_str != NULL, "unexpected NULL thread name");
3082 return name_str;
3083 }
3084
3085
3086 const char* JavaThread::get_threadgroup_name() const {
3087 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3088 oop thread_obj = threadObj();
3089 if (thread_obj != NULL) {
3090 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3091 if (thread_group != NULL) {
3092 // ThreadGroup.name can be null
3093 return java_lang_ThreadGroup::name(thread_group);
3094 }
3095 }
3096 return NULL;
3097 }
3098
3099 const char* JavaThread::get_parent_name() const {
3100 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3101 oop thread_obj = threadObj();
3102 if (thread_obj != NULL) {
3103 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3104 if (thread_group != NULL) {
3105 oop parent = java_lang_ThreadGroup::parent(thread_group);
3106 if (parent != NULL) {
3107 // ThreadGroup.name can be null
3108 return java_lang_ThreadGroup::name(parent);
3109 }
3110 }
3111 }
3112 return NULL;
3113 }
3114
3115 ThreadPriority JavaThread::java_priority() const {
3116 oop thr_oop = threadObj();
3117 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3118 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3119 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3120 return priority;
3121 }
3122
3123 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3124
3125 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3126 // Link Java Thread object <-> C++ Thread
3127
3128 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3129 // and put it into a new Handle. The Handle "thread_oop" can then
3130 // be used to pass the C++ thread object to other methods.
3131
3132 // Set the Java level thread object (jthread) field of the
3133 // new thread (a JavaThread *) to C++ thread object using the
3134 // "thread_oop" handle.
3135
3136 // Set the thread field (a JavaThread *) of the
3137 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3138
3139 Handle thread_oop(Thread::current(),
3140 JNIHandles::resolve_non_null(jni_thread));
3141 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3142 "must be initialized");
3143 set_threadObj(thread_oop());
3144 java_lang_Thread::set_thread(thread_oop(), this);
3145
3146 if (prio == NoPriority) {
3147 prio = java_lang_Thread::priority(thread_oop());
3148 assert(prio != NoPriority, "A valid priority should be present");
3149 }
3150
3151 // Push the Java priority down to the native thread; needs Threads_lock
3152 Thread::set_priority(this, prio);
3153
3154 prepare_ext();
3155
3156 // Add the new thread to the Threads list and set it in motion.
3157 // We must have threads lock in order to call Threads::add.
3158 // It is crucial that we do not block before the thread is
3159 // added to the Threads list for if a GC happens, then the java_thread oop
3160 // will not be visited by GC.
3161 Threads::add(this);
3162 }
3163
3164 oop JavaThread::current_park_blocker() {
3165 // Support for JSR-166 locks
3166 oop thread_oop = threadObj();
3167 if (thread_oop != NULL &&
3168 JDK_Version::current().supports_thread_park_blocker()) {
3169 return java_lang_Thread::park_blocker(thread_oop);
3170 }
3171 return NULL;
3172 }
3173
3174
3175 void JavaThread::print_stack_on(outputStream* st) {
3176 if (!has_last_Java_frame()) return;
3177 ResourceMark rm;
3178 HandleMark hm;
3179
3180 RegisterMap reg_map(this);
3181 vframe* start_vf = last_java_vframe(®_map);
3182 int count = 0;
3183 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3184 if (f->is_java_frame()) {
3185 javaVFrame* jvf = javaVFrame::cast(f);
3186 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3187
3188 // Print out lock information
3189 if (JavaMonitorsInStackTrace) {
3190 jvf->print_lock_info_on(st, count);
3191 }
3192 } else {
3193 // Ignore non-Java frames
3194 }
3195
3196 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3197 count++;
3198 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3199 }
3200 }
3201
3202
3203 // JVMTI PopFrame support
3204 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3205 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3206 if (in_bytes(size_in_bytes) != 0) {
3207 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3208 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3209 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3210 }
3211 }
3212
3213 void* JavaThread::popframe_preserved_args() {
3214 return _popframe_preserved_args;
3215 }
3216
3217 ByteSize JavaThread::popframe_preserved_args_size() {
3218 return in_ByteSize(_popframe_preserved_args_size);
3219 }
3220
3221 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3222 int sz = in_bytes(popframe_preserved_args_size());
3223 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3224 return in_WordSize(sz / wordSize);
3225 }
3226
3227 void JavaThread::popframe_free_preserved_args() {
3228 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3229 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3230 _popframe_preserved_args = NULL;
3231 _popframe_preserved_args_size = 0;
3232 }
3233
3234 #ifndef PRODUCT
3235
3236 void JavaThread::trace_frames() {
3237 tty->print_cr("[Describe stack]");
3238 int frame_no = 1;
3239 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3240 tty->print(" %d. ", frame_no++);
3241 fst.current()->print_value_on(tty, this);
3242 tty->cr();
3243 }
3244 }
3245
3246 class PrintAndVerifyOopClosure: public OopClosure {
3247 protected:
3248 template <class T> inline void do_oop_work(T* p) {
3249 oop obj = oopDesc::load_decode_heap_oop(p);
3250 if (obj == NULL) return;
3251 tty->print(INTPTR_FORMAT ": ", p2i(p));
3252 if (oopDesc::is_oop_or_null(obj)) {
3253 if (obj->is_objArray()) {
3254 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3255 } else {
3256 obj->print();
3257 }
3258 } else {
3259 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3260 }
3261 tty->cr();
3262 }
3263 public:
3264 virtual void do_oop(oop* p) { do_oop_work(p); }
3265 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3266 };
3267
3268
3269 static void oops_print(frame* f, const RegisterMap *map) {
3270 PrintAndVerifyOopClosure print;
3271 f->print_value();
3272 f->oops_do(&print, NULL, (RegisterMap*)map);
3273 }
3274
3275 // Print our all the locations that contain oops and whether they are
3276 // valid or not. This useful when trying to find the oldest frame
3277 // where an oop has gone bad since the frame walk is from youngest to
3278 // oldest.
3279 void JavaThread::trace_oops() {
3280 tty->print_cr("[Trace oops]");
3281 frames_do(oops_print);
3282 }
3283
3284
3285 #ifdef ASSERT
3286 // Print or validate the layout of stack frames
3287 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3288 ResourceMark rm;
3289 PRESERVE_EXCEPTION_MARK;
3290 FrameValues values;
3291 int frame_no = 0;
3292 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3293 fst.current()->describe(values, ++frame_no);
3294 if (depth == frame_no) break;
3295 }
3296 if (validate_only) {
3297 values.validate();
3298 } else {
3299 tty->print_cr("[Describe stack layout]");
3300 values.print(this);
3301 }
3302 }
3303 #endif
3304
3305 void JavaThread::trace_stack_from(vframe* start_vf) {
3306 ResourceMark rm;
3307 int vframe_no = 1;
3308 for (vframe* f = start_vf; f; f = f->sender()) {
3309 if (f->is_java_frame()) {
3310 javaVFrame::cast(f)->print_activation(vframe_no++);
3311 } else {
3312 f->print();
3313 }
3314 if (vframe_no > StackPrintLimit) {
3315 tty->print_cr("...<more frames>...");
3316 return;
3317 }
3318 }
3319 }
3320
3321
3322 void JavaThread::trace_stack() {
3323 if (!has_last_Java_frame()) return;
3324 ResourceMark rm;
3325 HandleMark hm;
3326 RegisterMap reg_map(this);
3327 trace_stack_from(last_java_vframe(®_map));
3328 }
3329
3330
3331 #endif // PRODUCT
3332
3333
3334 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3335 assert(reg_map != NULL, "a map must be given");
3336 frame f = last_frame();
3337 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3338 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3339 }
3340 return NULL;
3341 }
3342
3343
3344 Klass* JavaThread::security_get_caller_class(int depth) {
3345 vframeStream vfst(this);
3346 vfst.security_get_caller_frame(depth);
3347 if (!vfst.at_end()) {
3348 return vfst.method()->method_holder();
3349 }
3350 return NULL;
3351 }
3352
3353 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3354 assert(thread->is_Compiler_thread(), "must be compiler thread");
3355 CompileBroker::compiler_thread_loop();
3356 }
3357
3358 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3359 NMethodSweeper::sweeper_loop();
3360 }
3361
3362 // Create a CompilerThread
3363 CompilerThread::CompilerThread(CompileQueue* queue,
3364 CompilerCounters* counters)
3365 : JavaThread(&compiler_thread_entry) {
3366 _env = NULL;
3367 _log = NULL;
3368 _task = NULL;
3369 _queue = queue;
3370 _counters = counters;
3371 _buffer_blob = NULL;
3372 _compiler = NULL;
3373
3374 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3375 resource_area()->bias_to(mtCompiler);
3376
3377 #ifndef PRODUCT
3378 _ideal_graph_printer = NULL;
3379 #endif
3380 }
3381
3382 bool CompilerThread::can_call_java() const {
3383 return _compiler != NULL && _compiler->is_jvmci();
3384 }
3385
3386 // Create sweeper thread
3387 CodeCacheSweeperThread::CodeCacheSweeperThread()
3388 : JavaThread(&sweeper_thread_entry) {
3389 _scanned_compiled_method = NULL;
3390 }
3391
3392 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3393 JavaThread::oops_do(f, cf);
3394 if (_scanned_compiled_method != NULL && cf != NULL) {
3395 // Safepoints can occur when the sweeper is scanning an nmethod so
3396 // process it here to make sure it isn't unloaded in the middle of
3397 // a scan.
3398 cf->do_code_blob(_scanned_compiled_method);
3399 }
3400 }
3401
3402 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3403 JavaThread::nmethods_do(cf);
3404 if (_scanned_compiled_method != NULL && cf != NULL) {
3405 // Safepoints can occur when the sweeper is scanning an nmethod so
3406 // process it here to make sure it isn't unloaded in the middle of
3407 // a scan.
3408 cf->do_code_blob(_scanned_compiled_method);
3409 }
3410 }
3411
3412
3413 // ======= Threads ========
3414
3415 // The Threads class links together all active threads, and provides
3416 // operations over all threads. It is protected by the Threads_lock,
3417 // which is also used in other global contexts like safepointing.
3418 // ThreadsListHandles are used to safely perform operations on one
3419 // or more threads without the risk of the thread exiting during the
3420 // operation.
3421 //
3422 // Note: The Threads_lock is currently more widely used than we
3423 // would like. We are actively migrating Threads_lock uses to other
3424 // mechanisms in order to reduce Threads_lock contention.
3425
3426 JavaThread* Threads::_thread_list = NULL;
3427 int Threads::_number_of_threads = 0;
3428 int Threads::_number_of_non_daemon_threads = 0;
3429 int Threads::_return_code = 0;
3430 int Threads::_thread_claim_parity = 0;
3431 size_t JavaThread::_stack_size_at_create = 0;
3432
3433 #ifdef ASSERT
3434 bool Threads::_vm_complete = false;
3435 #endif
3436
3437 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3438 Prefetch::read((void*)addr, prefetch_interval);
3439 return *addr;
3440 }
3441
3442 // Possibly the ugliest for loop the world has seen. C++ does not allow
3443 // multiple types in the declaration section of the for loop. In this case
3444 // we are only dealing with pointers and hence can cast them. It looks ugly
3445 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3446 #define DO_JAVA_THREADS(LIST, X) \
3447 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3448 *MACRO_list = (JavaThread*)(LIST), \
3449 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3450 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3451 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3452 MACRO_current_p != MACRO_end; \
3453 MACRO_current_p++, \
3454 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3455
3456 // All JavaThreads
3457 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3458
3459 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3460 void Threads::threads_do(ThreadClosure* tc) {
3461 assert_locked_or_safepoint(Threads_lock);
3462 // ALL_JAVA_THREADS iterates through all JavaThreads
3463 ALL_JAVA_THREADS(p) {
3464 tc->do_thread(p);
3465 }
3466 // Someday we could have a table or list of all non-JavaThreads.
3467 // For now, just manually iterate through them.
3468 tc->do_thread(VMThread::vm_thread());
3469 Universe::heap()->gc_threads_do(tc);
3470 WatcherThread *wt = WatcherThread::watcher_thread();
3471 // Strictly speaking, the following NULL check isn't sufficient to make sure
3472 // the data for WatcherThread is still valid upon being examined. However,
3473 // considering that WatchThread terminates when the VM is on the way to
3474 // exit at safepoint, the chance of the above is extremely small. The right
3475 // way to prevent termination of WatcherThread would be to acquire
3476 // Terminator_lock, but we can't do that without violating the lock rank
3477 // checking in some cases.
3478 if (wt != NULL) {
3479 tc->do_thread(wt);
3480 }
3481
3482 // If CompilerThreads ever become non-JavaThreads, add them here
3483 }
3484
3485 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3486 int cp = Threads::thread_claim_parity();
3487 ALL_JAVA_THREADS(p) {
3488 if (p->claim_oops_do(is_par, cp)) {
3489 tc->do_thread(p);
3490 }
3491 }
3492 VMThread* vmt = VMThread::vm_thread();
3493 if (vmt->claim_oops_do(is_par, cp)) {
3494 tc->do_thread(vmt);
3495 }
3496 }
3497
3498 // The system initialization in the library has three phases.
3499 //
3500 // Phase 1: java.lang.System class initialization
3501 // java.lang.System is a primordial class loaded and initialized
3502 // by the VM early during startup. java.lang.System.<clinit>
3503 // only does registerNatives and keeps the rest of the class
3504 // initialization work later until thread initialization completes.
3505 //
3506 // System.initPhase1 initializes the system properties, the static
3507 // fields in, out, and err. Set up java signal handlers, OS-specific
3508 // system settings, and thread group of the main thread.
3509 static void call_initPhase1(TRAPS) {
3510 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3511 JavaValue result(T_VOID);
3512 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3513 vmSymbols::void_method_signature(), CHECK);
3514 }
3515
3516 // Phase 2. Module system initialization
3517 // This will initialize the module system. Only java.base classes
3518 // can be loaded until phase 2 completes.
3519 //
3520 // Call System.initPhase2 after the compiler initialization and jsr292
3521 // classes get initialized because module initialization runs a lot of java
3522 // code, that for performance reasons, should be compiled. Also, this will
3523 // enable the startup code to use lambda and other language features in this
3524 // phase and onward.
3525 //
3526 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3527 static void call_initPhase2(TRAPS) {
3528 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3529
3530 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3531
3532 JavaValue result(T_INT);
3533 JavaCallArguments args;
3534 args.push_int(DisplayVMOutputToStderr);
3535 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3536 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3537 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3538 if (result.get_jint() != JNI_OK) {
3539 vm_exit_during_initialization(); // no message or exception
3540 }
3541
3542 universe_post_module_init();
3543 }
3544
3545 // Phase 3. final setup - set security manager, system class loader and TCCL
3546 //
3547 // This will instantiate and set the security manager, set the system class
3548 // loader as well as the thread context class loader. The security manager
3549 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3550 // other modules or the application's classpath.
3551 static void call_initPhase3(TRAPS) {
3552 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3553 JavaValue result(T_VOID);
3554 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3555 vmSymbols::void_method_signature(), CHECK);
3556 }
3557
3558 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3559 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3560
3561 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3562 create_vm_init_libraries();
3563 }
3564
3565 initialize_class(vmSymbols::java_lang_String(), CHECK);
3566
3567 // Inject CompactStrings value after the static initializers for String ran.
3568 java_lang_String::set_compact_strings(CompactStrings);
3569
3570 // Initialize java_lang.System (needed before creating the thread)
3571 initialize_class(vmSymbols::java_lang_System(), CHECK);
3572 // The VM creates & returns objects of this class. Make sure it's initialized.
3573 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3574 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3575 Handle thread_group = create_initial_thread_group(CHECK);
3576 Universe::set_main_thread_group(thread_group());
3577 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3578 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3579 main_thread->set_threadObj(thread_object);
3580 // Set thread status to running since main thread has
3581 // been started and running.
3582 java_lang_Thread::set_thread_status(thread_object,
3583 java_lang_Thread::RUNNABLE);
3584
3585 // The VM creates objects of this class.
3586 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3587
3588 // The VM preresolves methods to these classes. Make sure that they get initialized
3589 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3590 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3591
3592 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3593 call_initPhase1(CHECK);
3594
3595 // get the Java runtime name after java.lang.System is initialized
3596 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3597 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3598
3599 // an instance of OutOfMemory exception has been allocated earlier
3600 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3601 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3602 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3603 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3604 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3605 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3606 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3607 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3608 }
3609
3610 void Threads::initialize_jsr292_core_classes(TRAPS) {
3611 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3612
3613 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3614 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3615 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3616 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3617 }
3618
3619 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3620 extern void JDK_Version_init();
3621
3622 // Preinitialize version info.
3623 VM_Version::early_initialize();
3624
3625 // Check version
3626 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3627
3628 // Initialize library-based TLS
3629 ThreadLocalStorage::init();
3630
3631 // Initialize the output stream module
3632 ostream_init();
3633
3634 // Process java launcher properties.
3635 Arguments::process_sun_java_launcher_properties(args);
3636
3637 // Initialize the os module
3638 os::init();
3639
3640 // Record VM creation timing statistics
3641 TraceVmCreationTime create_vm_timer;
3642 create_vm_timer.start();
3643
3644 // Initialize system properties.
3645 Arguments::init_system_properties();
3646
3647 // So that JDK version can be used as a discriminator when parsing arguments
3648 JDK_Version_init();
3649
3650 // Update/Initialize System properties after JDK version number is known
3651 Arguments::init_version_specific_system_properties();
3652
3653 // Make sure to initialize log configuration *before* parsing arguments
3654 LogConfiguration::initialize(create_vm_timer.begin_time());
3655
3656 // Parse arguments
3657 // Note: this internally calls os::init_container_support()
3658 jint parse_result = Arguments::parse(args);
3659 if (parse_result != JNI_OK) return parse_result;
3660
3661 os::init_before_ergo();
3662
3663 jint ergo_result = Arguments::apply_ergo();
3664 if (ergo_result != JNI_OK) return ergo_result;
3665
3666 // Final check of all ranges after ergonomics which may change values.
3667 if (!CommandLineFlagRangeList::check_ranges()) {
3668 return JNI_EINVAL;
3669 }
3670
3671 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3672 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3673 if (!constraint_result) {
3674 return JNI_EINVAL;
3675 }
3676
3677 CommandLineFlagWriteableList::mark_startup();
3678
3679 if (PauseAtStartup) {
3680 os::pause();
3681 }
3682
3683 HOTSPOT_VM_INIT_BEGIN();
3684
3685 // Timing (must come after argument parsing)
3686 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3687
3688 // Initialize the os module after parsing the args
3689 jint os_init_2_result = os::init_2();
3690 if (os_init_2_result != JNI_OK) return os_init_2_result;
3691
3692 SafepointMechanism::initialize();
3693
3694 jint adjust_after_os_result = Arguments::adjust_after_os();
3695 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3696
3697 // Initialize output stream logging
3698 ostream_init_log();
3699
3700 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3701 // Must be before create_vm_init_agents()
3702 if (Arguments::init_libraries_at_startup()) {
3703 convert_vm_init_libraries_to_agents();
3704 }
3705
3706 // Launch -agentlib/-agentpath and converted -Xrun agents
3707 if (Arguments::init_agents_at_startup()) {
3708 create_vm_init_agents();
3709 }
3710
3711 // Initialize Threads state
3712 _thread_list = NULL;
3713 _number_of_threads = 0;
3714 _number_of_non_daemon_threads = 0;
3715
3716 // Initialize global data structures and create system classes in heap
3717 vm_init_globals();
3718
3719 #if INCLUDE_JVMCI
3720 if (JVMCICounterSize > 0) {
3721 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3722 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3723 } else {
3724 JavaThread::_jvmci_old_thread_counters = NULL;
3725 }
3726 #endif // INCLUDE_JVMCI
3727
3728 // Attach the main thread to this os thread
3729 JavaThread* main_thread = new JavaThread();
3730 main_thread->set_thread_state(_thread_in_vm);
3731 main_thread->initialize_thread_current();
3732 // must do this before set_active_handles
3733 main_thread->record_stack_base_and_size();
3734 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3735
3736 if (!main_thread->set_as_starting_thread()) {
3737 vm_shutdown_during_initialization(
3738 "Failed necessary internal allocation. Out of swap space");
3739 main_thread->smr_delete();
3740 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3741 return JNI_ENOMEM;
3742 }
3743
3744 // Enable guard page *after* os::create_main_thread(), otherwise it would
3745 // crash Linux VM, see notes in os_linux.cpp.
3746 main_thread->create_stack_guard_pages();
3747
3748 // Initialize Java-Level synchronization subsystem
3749 ObjectMonitor::Initialize();
3750
3751 // Initialize global modules
3752 jint status = init_globals();
3753 if (status != JNI_OK) {
3754 main_thread->smr_delete();
3755 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3756 return status;
3757 }
3758
3759 if (TRACE_INITIALIZE() != JNI_OK) {
3760 vm_exit_during_initialization("Failed to initialize tracing backend");
3761 }
3762
3763 // Should be done after the heap is fully created
3764 main_thread->cache_global_variables();
3765
3766 HandleMark hm;
3767
3768 { MutexLocker mu(Threads_lock);
3769 Threads::add(main_thread);
3770 }
3771
3772 // Any JVMTI raw monitors entered in onload will transition into
3773 // real raw monitor. VM is setup enough here for raw monitor enter.
3774 JvmtiExport::transition_pending_onload_raw_monitors();
3775
3776 // Create the VMThread
3777 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3778
3779 VMThread::create();
3780 Thread* vmthread = VMThread::vm_thread();
3781
3782 if (!os::create_thread(vmthread, os::vm_thread)) {
3783 vm_exit_during_initialization("Cannot create VM thread. "
3784 "Out of system resources.");
3785 }
3786
3787 // Wait for the VM thread to become ready, and VMThread::run to initialize
3788 // Monitors can have spurious returns, must always check another state flag
3789 {
3790 MutexLocker ml(Notify_lock);
3791 os::start_thread(vmthread);
3792 while (vmthread->active_handles() == NULL) {
3793 Notify_lock->wait();
3794 }
3795 }
3796 }
3797
3798 assert(Universe::is_fully_initialized(), "not initialized");
3799 if (VerifyDuringStartup) {
3800 // Make sure we're starting with a clean slate.
3801 VM_Verify verify_op;
3802 VMThread::execute(&verify_op);
3803 }
3804
3805 Thread* THREAD = Thread::current();
3806
3807 // Always call even when there are not JVMTI environments yet, since environments
3808 // may be attached late and JVMTI must track phases of VM execution
3809 JvmtiExport::enter_early_start_phase();
3810
3811 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3812 JvmtiExport::post_early_vm_start();
3813
3814 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3815
3816 // We need this for ClassDataSharing - the initial vm.info property is set
3817 // with the default value of CDS "sharing" which may be reset through
3818 // command line options.
3819 reset_vm_info_property(CHECK_JNI_ERR);
3820
3821 quicken_jni_functions();
3822
3823 // No more stub generation allowed after that point.
3824 StubCodeDesc::freeze();
3825
3826 // Set flag that basic initialization has completed. Used by exceptions and various
3827 // debug stuff, that does not work until all basic classes have been initialized.
3828 set_init_completed();
3829
3830 LogConfiguration::post_initialize();
3831 Metaspace::post_initialize();
3832
3833 HOTSPOT_VM_INIT_END();
3834
3835 // record VM initialization completion time
3836 #if INCLUDE_MANAGEMENT
3837 Management::record_vm_init_completed();
3838 #endif // INCLUDE_MANAGEMENT
3839
3840 // Signal Dispatcher needs to be started before VMInit event is posted
3841 os::signal_init(CHECK_JNI_ERR);
3842
3843 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3844 if (!DisableAttachMechanism) {
3845 AttachListener::vm_start();
3846 if (StartAttachListener || AttachListener::init_at_startup()) {
3847 AttachListener::init();
3848 }
3849 }
3850
3851 // Launch -Xrun agents
3852 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3853 // back-end can launch with -Xdebug -Xrunjdwp.
3854 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3855 create_vm_init_libraries();
3856 }
3857
3858 if (CleanChunkPoolAsync) {
3859 Chunk::start_chunk_pool_cleaner_task();
3860 }
3861
3862 // initialize compiler(s)
3863 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3864 CompileBroker::compilation_init(CHECK_JNI_ERR);
3865 #endif
3866
3867 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3868 // It is done after compilers are initialized, because otherwise compilations of
3869 // signature polymorphic MH intrinsics can be missed
3870 // (see SystemDictionary::find_method_handle_intrinsic).
3871 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3872
3873 // This will initialize the module system. Only java.base classes can be
3874 // loaded until phase 2 completes
3875 call_initPhase2(CHECK_JNI_ERR);
3876
3877 // Always call even when there are not JVMTI environments yet, since environments
3878 // may be attached late and JVMTI must track phases of VM execution
3879 JvmtiExport::enter_start_phase();
3880
3881 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3882 JvmtiExport::post_vm_start();
3883
3884 // Final system initialization including security manager and system class loader
3885 call_initPhase3(CHECK_JNI_ERR);
3886
3887 // cache the system and platform class loaders
3888 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3889
3890 #if INCLUDE_JVMCI
3891 if (EnableJVMCI) {
3892 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3893 // The JVMCI Java initialization code will read this flag and
3894 // do the printing if it's set.
3895 bool init = JVMCIPrintProperties;
3896
3897 if (!init) {
3898 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3899 // compilations via JVMCI will not actually block until JVMCI is initialized.
3900 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3901 }
3902
3903 if (init) {
3904 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3905 }
3906 }
3907 #endif
3908
3909 // Always call even when there are not JVMTI environments yet, since environments
3910 // may be attached late and JVMTI must track phases of VM execution
3911 JvmtiExport::enter_live_phase();
3912
3913 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3914 JvmtiExport::post_vm_initialized();
3915
3916 if (TRACE_START() != JNI_OK) {
3917 vm_exit_during_initialization("Failed to start tracing backend.");
3918 }
3919
3920 #if INCLUDE_MANAGEMENT
3921 Management::initialize(THREAD);
3922
3923 if (HAS_PENDING_EXCEPTION) {
3924 // management agent fails to start possibly due to
3925 // configuration problem and is responsible for printing
3926 // stack trace if appropriate. Simply exit VM.
3927 vm_exit(1);
3928 }
3929 #endif // INCLUDE_MANAGEMENT
3930
3931 if (MemProfiling) MemProfiler::engage();
3932 StatSampler::engage();
3933 if (CheckJNICalls) JniPeriodicChecker::engage();
3934
3935 BiasedLocking::init();
3936
3937 #if INCLUDE_RTM_OPT
3938 RTMLockingCounters::init();
3939 #endif
3940
3941 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3942 call_postVMInitHook(THREAD);
3943 // The Java side of PostVMInitHook.run must deal with all
3944 // exceptions and provide means of diagnosis.
3945 if (HAS_PENDING_EXCEPTION) {
3946 CLEAR_PENDING_EXCEPTION;
3947 }
3948 }
3949
3950 {
3951 MutexLocker ml(PeriodicTask_lock);
3952 // Make sure the WatcherThread can be started by WatcherThread::start()
3953 // or by dynamic enrollment.
3954 WatcherThread::make_startable();
3955 // Start up the WatcherThread if there are any periodic tasks
3956 // NOTE: All PeriodicTasks should be registered by now. If they
3957 // aren't, late joiners might appear to start slowly (we might
3958 // take a while to process their first tick).
3959 if (PeriodicTask::num_tasks() > 0) {
3960 WatcherThread::start();
3961 }
3962 }
3963
3964 create_vm_timer.end();
3965 #ifdef ASSERT
3966 _vm_complete = true;
3967 #endif
3968
3969 if (DumpSharedSpaces) {
3970 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3971 ShouldNotReachHere();
3972 }
3973
3974 return JNI_OK;
3975 }
3976
3977 // type for the Agent_OnLoad and JVM_OnLoad entry points
3978 extern "C" {
3979 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3980 }
3981 // Find a command line agent library and return its entry point for
3982 // -agentlib: -agentpath: -Xrun
3983 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3984 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3985 const char *on_load_symbols[],
3986 size_t num_symbol_entries) {
3987 OnLoadEntry_t on_load_entry = NULL;
3988 void *library = NULL;
3989
3990 if (!agent->valid()) {
3991 char buffer[JVM_MAXPATHLEN];
3992 char ebuf[1024] = "";
3993 const char *name = agent->name();
3994 const char *msg = "Could not find agent library ";
3995
3996 // First check to see if agent is statically linked into executable
3997 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3998 library = agent->os_lib();
3999 } else if (agent->is_absolute_path()) {
4000 library = os::dll_load(name, ebuf, sizeof ebuf);
4001 if (library == NULL) {
4002 const char *sub_msg = " in absolute path, with error: ";
4003 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4004 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4005 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4006 // If we can't find the agent, exit.
4007 vm_exit_during_initialization(buf, NULL);
4008 FREE_C_HEAP_ARRAY(char, buf);
4009 }
4010 } else {
4011 // Try to load the agent from the standard dll directory
4012 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4013 name)) {
4014 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4015 }
4016 if (library == NULL) { // Try the library path directory.
4017 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4018 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4019 }
4020 if (library == NULL) {
4021 const char *sub_msg = " on the library path, with error: ";
4022 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4023
4024 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4025 strlen(ebuf) + strlen(sub_msg2) + 1;
4026 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4027 if (!agent->is_instrument_lib()) {
4028 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4029 } else {
4030 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4031 }
4032 // If we can't find the agent, exit.
4033 vm_exit_during_initialization(buf, NULL);
4034 FREE_C_HEAP_ARRAY(char, buf);
4035 }
4036 }
4037 }
4038 agent->set_os_lib(library);
4039 agent->set_valid();
4040 }
4041
4042 // Find the OnLoad function.
4043 on_load_entry =
4044 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4045 false,
4046 on_load_symbols,
4047 num_symbol_entries));
4048 return on_load_entry;
4049 }
4050
4051 // Find the JVM_OnLoad entry point
4052 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4053 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4054 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4055 }
4056
4057 // Find the Agent_OnLoad entry point
4058 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4059 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4060 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4061 }
4062
4063 // For backwards compatibility with -Xrun
4064 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4065 // treated like -agentpath:
4066 // Must be called before agent libraries are created
4067 void Threads::convert_vm_init_libraries_to_agents() {
4068 AgentLibrary* agent;
4069 AgentLibrary* next;
4070
4071 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4072 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4073 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4074
4075 // If there is an JVM_OnLoad function it will get called later,
4076 // otherwise see if there is an Agent_OnLoad
4077 if (on_load_entry == NULL) {
4078 on_load_entry = lookup_agent_on_load(agent);
4079 if (on_load_entry != NULL) {
4080 // switch it to the agent list -- so that Agent_OnLoad will be called,
4081 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4082 Arguments::convert_library_to_agent(agent);
4083 } else {
4084 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4085 }
4086 }
4087 }
4088 }
4089
4090 // Create agents for -agentlib: -agentpath: and converted -Xrun
4091 // Invokes Agent_OnLoad
4092 // Called very early -- before JavaThreads exist
4093 void Threads::create_vm_init_agents() {
4094 extern struct JavaVM_ main_vm;
4095 AgentLibrary* agent;
4096
4097 JvmtiExport::enter_onload_phase();
4098
4099 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4100 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4101
4102 if (on_load_entry != NULL) {
4103 // Invoke the Agent_OnLoad function
4104 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4105 if (err != JNI_OK) {
4106 vm_exit_during_initialization("agent library failed to init", agent->name());
4107 }
4108 } else {
4109 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4110 }
4111 }
4112 JvmtiExport::enter_primordial_phase();
4113 }
4114
4115 extern "C" {
4116 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4117 }
4118
4119 void Threads::shutdown_vm_agents() {
4120 // Send any Agent_OnUnload notifications
4121 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4122 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4123 extern struct JavaVM_ main_vm;
4124 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4125
4126 // Find the Agent_OnUnload function.
4127 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4128 os::find_agent_function(agent,
4129 false,
4130 on_unload_symbols,
4131 num_symbol_entries));
4132
4133 // Invoke the Agent_OnUnload function
4134 if (unload_entry != NULL) {
4135 JavaThread* thread = JavaThread::current();
4136 ThreadToNativeFromVM ttn(thread);
4137 HandleMark hm(thread);
4138 (*unload_entry)(&main_vm);
4139 }
4140 }
4141 }
4142
4143 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4144 // Invokes JVM_OnLoad
4145 void Threads::create_vm_init_libraries() {
4146 extern struct JavaVM_ main_vm;
4147 AgentLibrary* agent;
4148
4149 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4150 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4151
4152 if (on_load_entry != NULL) {
4153 // Invoke the JVM_OnLoad function
4154 JavaThread* thread = JavaThread::current();
4155 ThreadToNativeFromVM ttn(thread);
4156 HandleMark hm(thread);
4157 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4158 if (err != JNI_OK) {
4159 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4160 }
4161 } else {
4162 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4163 }
4164 }
4165 }
4166
4167
4168 // Last thread running calls java.lang.Shutdown.shutdown()
4169 void JavaThread::invoke_shutdown_hooks() {
4170 HandleMark hm(this);
4171
4172 // We could get here with a pending exception, if so clear it now.
4173 if (this->has_pending_exception()) {
4174 this->clear_pending_exception();
4175 }
4176
4177 EXCEPTION_MARK;
4178 Klass* shutdown_klass =
4179 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4180 THREAD);
4181 if (shutdown_klass != NULL) {
4182 // SystemDictionary::resolve_or_null will return null if there was
4183 // an exception. If we cannot load the Shutdown class, just don't
4184 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4185 // and finalizers (if runFinalizersOnExit is set) won't be run.
4186 // Note that if a shutdown hook was registered or runFinalizersOnExit
4187 // was called, the Shutdown class would have already been loaded
4188 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4189 JavaValue result(T_VOID);
4190 JavaCalls::call_static(&result,
4191 shutdown_klass,
4192 vmSymbols::shutdown_method_name(),
4193 vmSymbols::void_method_signature(),
4194 THREAD);
4195 }
4196 CLEAR_PENDING_EXCEPTION;
4197 }
4198
4199 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4200 // the program falls off the end of main(). Another VM exit path is through
4201 // vm_exit() when the program calls System.exit() to return a value or when
4202 // there is a serious error in VM. The two shutdown paths are not exactly
4203 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4204 // and VM_Exit op at VM level.
4205 //
4206 // Shutdown sequence:
4207 // + Shutdown native memory tracking if it is on
4208 // + Wait until we are the last non-daemon thread to execute
4209 // <-- every thing is still working at this moment -->
4210 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4211 // shutdown hooks, run finalizers if finalization-on-exit
4212 // + Call before_exit(), prepare for VM exit
4213 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4214 // currently the only user of this mechanism is File.deleteOnExit())
4215 // > stop StatSampler, watcher thread, CMS threads,
4216 // post thread end and vm death events to JVMTI,
4217 // stop signal thread
4218 // + Call JavaThread::exit(), it will:
4219 // > release JNI handle blocks, remove stack guard pages
4220 // > remove this thread from Threads list
4221 // <-- no more Java code from this thread after this point -->
4222 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4223 // the compiler threads at safepoint
4224 // <-- do not use anything that could get blocked by Safepoint -->
4225 // + Disable tracing at JNI/JVM barriers
4226 // + Set _vm_exited flag for threads that are still running native code
4227 // + Delete this thread
4228 // + Call exit_globals()
4229 // > deletes tty
4230 // > deletes PerfMemory resources
4231 // + Return to caller
4232
4233 bool Threads::destroy_vm() {
4234 JavaThread* thread = JavaThread::current();
4235
4236 #ifdef ASSERT
4237 _vm_complete = false;
4238 #endif
4239 // Wait until we are the last non-daemon thread to execute
4240 { MutexLocker nu(Threads_lock);
4241 while (Threads::number_of_non_daemon_threads() > 1)
4242 // This wait should make safepoint checks, wait without a timeout,
4243 // and wait as a suspend-equivalent condition.
4244 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4245 Mutex::_as_suspend_equivalent_flag);
4246 }
4247
4248 // Hang forever on exit if we are reporting an error.
4249 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4250 os::infinite_sleep();
4251 }
4252 os::wait_for_keypress_at_exit();
4253
4254 // run Java level shutdown hooks
4255 thread->invoke_shutdown_hooks();
4256
4257 before_exit(thread);
4258
4259 thread->exit(true);
4260
4261 // Stop VM thread.
4262 {
4263 // 4945125 The vm thread comes to a safepoint during exit.
4264 // GC vm_operations can get caught at the safepoint, and the
4265 // heap is unparseable if they are caught. Grab the Heap_lock
4266 // to prevent this. The GC vm_operations will not be able to
4267 // queue until after the vm thread is dead. After this point,
4268 // we'll never emerge out of the safepoint before the VM exits.
4269
4270 MutexLocker ml(Heap_lock);
4271
4272 VMThread::wait_for_vm_thread_exit();
4273 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4274 VMThread::destroy();
4275 }
4276
4277 // clean up ideal graph printers
4278 #if defined(COMPILER2) && !defined(PRODUCT)
4279 IdealGraphPrinter::clean_up();
4280 #endif
4281
4282 // Now, all Java threads are gone except daemon threads. Daemon threads
4283 // running Java code or in VM are stopped by the Safepoint. However,
4284 // daemon threads executing native code are still running. But they
4285 // will be stopped at native=>Java/VM barriers. Note that we can't
4286 // simply kill or suspend them, as it is inherently deadlock-prone.
4287
4288 VM_Exit::set_vm_exited();
4289
4290 notify_vm_shutdown();
4291
4292 // We are after VM_Exit::set_vm_exited() so we can't call
4293 // thread->smr_delete() or we will block on the Threads_lock.
4294 // Deleting the shutdown thread here is safe because another
4295 // JavaThread cannot have an active ThreadsListHandle for
4296 // this JavaThread.
4297 delete thread;
4298
4299 #if INCLUDE_JVMCI
4300 if (JVMCICounterSize > 0) {
4301 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4302 }
4303 #endif
4304
4305 // exit_globals() will delete tty
4306 exit_globals();
4307
4308 LogConfiguration::finalize();
4309
4310 return true;
4311 }
4312
4313
4314 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4315 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4316 return is_supported_jni_version(version);
4317 }
4318
4319
4320 jboolean Threads::is_supported_jni_version(jint version) {
4321 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4322 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4323 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4324 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4325 if (version == JNI_VERSION_9) return JNI_TRUE;
4326 if (version == JNI_VERSION_10) return JNI_TRUE;
4327 return JNI_FALSE;
4328 }
4329
4330
4331 void Threads::add(JavaThread* p, bool force_daemon) {
4332 // The threads lock must be owned at this point
4333 assert_locked_or_safepoint(Threads_lock);
4334
4335 // See the comment for this method in thread.hpp for its purpose and
4336 // why it is called here.
4337 p->initialize_queues();
4338 p->set_next(_thread_list);
4339 _thread_list = p;
4340
4341 // Once a JavaThread is added to the Threads list, smr_delete() has
4342 // to be used to delete it. Otherwise we can just delete it directly.
4343 p->set_on_thread_list();
4344
4345 _number_of_threads++;
4346 oop threadObj = p->threadObj();
4347 bool daemon = true;
4348 // Bootstrapping problem: threadObj can be null for initial
4349 // JavaThread (or for threads attached via JNI)
4350 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4351 _number_of_non_daemon_threads++;
4352 daemon = false;
4353 }
4354
4355 ThreadService::add_thread(p, daemon);
4356
4357 // Maintain fast thread list
4358 ThreadsSMRSupport::add_thread(p);
4359
4360 // Possible GC point.
4361 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4362 }
4363
4364 void Threads::remove(JavaThread* p) {
4365
4366 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4367 ObjectSynchronizer::omFlush(p);
4368
4369 // Extra scope needed for Thread_lock, so we can check
4370 // that we do not remove thread without safepoint code notice
4371 { MutexLocker ml(Threads_lock);
4372
4373 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4374
4375 // Maintain fast thread list
4376 ThreadsSMRSupport::remove_thread(p);
4377
4378 JavaThread* current = _thread_list;
4379 JavaThread* prev = NULL;
4380
4381 while (current != p) {
4382 prev = current;
4383 current = current->next();
4384 }
4385
4386 if (prev) {
4387 prev->set_next(current->next());
4388 } else {
4389 _thread_list = p->next();
4390 }
4391
4392 _number_of_threads--;
4393 oop threadObj = p->threadObj();
4394 bool daemon = true;
4395 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4396 _number_of_non_daemon_threads--;
4397 daemon = false;
4398
4399 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4400 // on destroy_vm will wake up.
4401 if (number_of_non_daemon_threads() == 1) {
4402 Threads_lock->notify_all();
4403 }
4404 }
4405 ThreadService::remove_thread(p, daemon);
4406
4407 // Make sure that safepoint code disregard this thread. This is needed since
4408 // the thread might mess around with locks after this point. This can cause it
4409 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4410 // of this thread since it is removed from the queue.
4411 p->set_terminated_value();
4412 } // unlock Threads_lock
4413
4414 // Since Events::log uses a lock, we grab it outside the Threads_lock
4415 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4416 }
4417
4418 // Operations on the Threads list for GC. These are not explicitly locked,
4419 // but the garbage collector must provide a safe context for them to run.
4420 // In particular, these things should never be called when the Threads_lock
4421 // is held by some other thread. (Note: the Safepoint abstraction also
4422 // uses the Threads_lock to guarantee this property. It also makes sure that
4423 // all threads gets blocked when exiting or starting).
4424
4425 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4426 ALL_JAVA_THREADS(p) {
4427 p->oops_do(f, cf);
4428 }
4429 VMThread::vm_thread()->oops_do(f, cf);
4430 }
4431
4432 void Threads::change_thread_claim_parity() {
4433 // Set the new claim parity.
4434 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4435 "Not in range.");
4436 _thread_claim_parity++;
4437 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4438 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4439 "Not in range.");
4440 }
4441
4442 #ifdef ASSERT
4443 void Threads::assert_all_threads_claimed() {
4444 ALL_JAVA_THREADS(p) {
4445 const int thread_parity = p->oops_do_parity();
4446 assert((thread_parity == _thread_claim_parity),
4447 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4448 }
4449 VMThread* vmt = VMThread::vm_thread();
4450 const int thread_parity = vmt->oops_do_parity();
4451 assert((thread_parity == _thread_claim_parity),
4452 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4453 }
4454 #endif // ASSERT
4455
4456 class ParallelOopsDoThreadClosure : public ThreadClosure {
4457 private:
4458 OopClosure* _f;
4459 CodeBlobClosure* _cf;
4460 public:
4461 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4462 void do_thread(Thread* t) {
4463 t->oops_do(_f, _cf);
4464 }
4465 };
4466
4467 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4468 ParallelOopsDoThreadClosure tc(f, cf);
4469 possibly_parallel_threads_do(is_par, &tc);
4470 }
4471
4472 #if INCLUDE_ALL_GCS
4473 // Used by ParallelScavenge
4474 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4475 ALL_JAVA_THREADS(p) {
4476 q->enqueue(new ThreadRootsTask(p));
4477 }
4478 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4479 }
4480
4481 // Used by Parallel Old
4482 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4483 ALL_JAVA_THREADS(p) {
4484 q->enqueue(new ThreadRootsMarkingTask(p));
4485 }
4486 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4487 }
4488 #endif // INCLUDE_ALL_GCS
4489
4490 void Threads::nmethods_do(CodeBlobClosure* cf) {
4491 ALL_JAVA_THREADS(p) {
4492 // This is used by the code cache sweeper to mark nmethods that are active
4493 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4494 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4495 if(!p->is_Code_cache_sweeper_thread()) {
4496 p->nmethods_do(cf);
4497 }
4498 }
4499 }
4500
4501 void Threads::metadata_do(void f(Metadata*)) {
4502 ALL_JAVA_THREADS(p) {
4503 p->metadata_do(f);
4504 }
4505 }
4506
4507 class ThreadHandlesClosure : public ThreadClosure {
4508 void (*_f)(Metadata*);
4509 public:
4510 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4511 virtual void do_thread(Thread* thread) {
4512 thread->metadata_handles_do(_f);
4513 }
4514 };
4515
4516 void Threads::metadata_handles_do(void f(Metadata*)) {
4517 // Only walk the Handles in Thread.
4518 ThreadHandlesClosure handles_closure(f);
4519 threads_do(&handles_closure);
4520 }
4521
4522 void Threads::deoptimized_wrt_marked_nmethods() {
4523 ALL_JAVA_THREADS(p) {
4524 p->deoptimized_wrt_marked_nmethods();
4525 }
4526 }
4527
4528
4529 // Get count Java threads that are waiting to enter the specified monitor.
4530 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4531 int count,
4532 address monitor) {
4533 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4534
4535 int i = 0;
4536 DO_JAVA_THREADS(t_list, p) {
4537 if (!p->can_call_java()) continue;
4538
4539 address pending = (address)p->current_pending_monitor();
4540 if (pending == monitor) { // found a match
4541 if (i < count) result->append(p); // save the first count matches
4542 i++;
4543 }
4544 }
4545
4546 return result;
4547 }
4548
4549
4550 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4551 address owner) {
4552 // NULL owner means not locked so we can skip the search
4553 if (owner == NULL) return NULL;
4554
4555 DO_JAVA_THREADS(t_list, p) {
4556 // first, see if owner is the address of a Java thread
4557 if (owner == (address)p) return p;
4558 }
4559
4560 // Cannot assert on lack of success here since this function may be
4561 // used by code that is trying to report useful problem information
4562 // like deadlock detection.
4563 if (UseHeavyMonitors) return NULL;
4564
4565 // If we didn't find a matching Java thread and we didn't force use of
4566 // heavyweight monitors, then the owner is the stack address of the
4567 // Lock Word in the owning Java thread's stack.
4568 //
4569 JavaThread* the_owner = NULL;
4570 DO_JAVA_THREADS(t_list, q) {
4571 if (q->is_lock_owned(owner)) {
4572 the_owner = q;
4573 break;
4574 }
4575 }
4576
4577 // cannot assert on lack of success here; see above comment
4578 return the_owner;
4579 }
4580
4581 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4582 void Threads::print_on(outputStream* st, bool print_stacks,
4583 bool internal_format, bool print_concurrent_locks) {
4584 char buf[32];
4585 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4586
4587 st->print_cr("Full thread dump %s (%s %s):",
4588 Abstract_VM_Version::vm_name(),
4589 Abstract_VM_Version::vm_release(),
4590 Abstract_VM_Version::vm_info_string());
4591 st->cr();
4592
4593 #if INCLUDE_SERVICES
4594 // Dump concurrent locks
4595 ConcurrentLocksDump concurrent_locks;
4596 if (print_concurrent_locks) {
4597 concurrent_locks.dump_at_safepoint();
4598 }
4599 #endif // INCLUDE_SERVICES
4600
4601 ThreadsSMRSupport::print_info_on(st);
4602 st->cr();
4603
4604 ALL_JAVA_THREADS(p) {
4605 ResourceMark rm;
4606 p->print_on(st);
4607 if (print_stacks) {
4608 if (internal_format) {
4609 p->trace_stack();
4610 } else {
4611 p->print_stack_on(st);
4612 }
4613 }
4614 st->cr();
4615 #if INCLUDE_SERVICES
4616 if (print_concurrent_locks) {
4617 concurrent_locks.print_locks_on(p, st);
4618 }
4619 #endif // INCLUDE_SERVICES
4620 }
4621
4622 VMThread::vm_thread()->print_on(st);
4623 st->cr();
4624 Universe::heap()->print_gc_threads_on(st);
4625 WatcherThread* wt = WatcherThread::watcher_thread();
4626 if (wt != NULL) {
4627 wt->print_on(st);
4628 st->cr();
4629 }
4630
4631 st->flush();
4632 }
4633
4634 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4635 int buflen, bool* found_current) {
4636 if (this_thread != NULL) {
4637 bool is_current = (current == this_thread);
4638 *found_current = *found_current || is_current;
4639 st->print("%s", is_current ? "=>" : " ");
4640
4641 st->print(PTR_FORMAT, p2i(this_thread));
4642 st->print(" ");
4643 this_thread->print_on_error(st, buf, buflen);
4644 st->cr();
4645 }
4646 }
4647
4648 class PrintOnErrorClosure : public ThreadClosure {
4649 outputStream* _st;
4650 Thread* _current;
4651 char* _buf;
4652 int _buflen;
4653 bool* _found_current;
4654 public:
4655 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4656 int buflen, bool* found_current) :
4657 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4658
4659 virtual void do_thread(Thread* thread) {
4660 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4661 }
4662 };
4663
4664 // Threads::print_on_error() is called by fatal error handler. It's possible
4665 // that VM is not at safepoint and/or current thread is inside signal handler.
4666 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4667 // memory (even in resource area), it might deadlock the error handler.
4668 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4669 int buflen) {
4670 ThreadsSMRSupport::print_info_on(st);
4671 st->cr();
4672
4673 bool found_current = false;
4674 st->print_cr("Java Threads: ( => current thread )");
4675 ALL_JAVA_THREADS(thread) {
4676 print_on_error(thread, st, current, buf, buflen, &found_current);
4677 }
4678 st->cr();
4679
4680 st->print_cr("Other Threads:");
4681 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4682 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4683
4684 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4685 Universe::heap()->gc_threads_do(&print_closure);
4686
4687 if (!found_current) {
4688 st->cr();
4689 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4690 current->print_on_error(st, buf, buflen);
4691 st->cr();
4692 }
4693 st->cr();
4694
4695 st->print_cr("Threads with active compile tasks:");
4696 print_threads_compiling(st, buf, buflen);
4697 }
4698
4699 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4700 ALL_JAVA_THREADS(thread) {
4701 if (thread->is_Compiler_thread()) {
4702 CompilerThread* ct = (CompilerThread*) thread;
4703
4704 // Keep task in local variable for NULL check.
4705 // ct->_task might be set to NULL by concurring compiler thread
4706 // because it completed the compilation. The task is never freed,
4707 // though, just returned to a free list.
4708 CompileTask* task = ct->task();
4709 if (task != NULL) {
4710 thread->print_name_on_error(st, buf, buflen);
4711 task->print(st, NULL, true, true);
4712 }
4713 }
4714 }
4715 }
4716
4717
4718 // Internal SpinLock and Mutex
4719 // Based on ParkEvent
4720
4721 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4722 //
4723 // We employ SpinLocks _only for low-contention, fixed-length
4724 // short-duration critical sections where we're concerned
4725 // about native mutex_t or HotSpot Mutex:: latency.
4726 // The mux construct provides a spin-then-block mutual exclusion
4727 // mechanism.
4728 //
4729 // Testing has shown that contention on the ListLock guarding gFreeList
4730 // is common. If we implement ListLock as a simple SpinLock it's common
4731 // for the JVM to devolve to yielding with little progress. This is true
4732 // despite the fact that the critical sections protected by ListLock are
4733 // extremely short.
4734 //
4735 // TODO-FIXME: ListLock should be of type SpinLock.
4736 // We should make this a 1st-class type, integrated into the lock
4737 // hierarchy as leaf-locks. Critically, the SpinLock structure
4738 // should have sufficient padding to avoid false-sharing and excessive
4739 // cache-coherency traffic.
4740
4741
4742 typedef volatile int SpinLockT;
4743
4744 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4745 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4746 return; // normal fast-path return
4747 }
4748
4749 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4750 TEVENT(SpinAcquire - ctx);
4751 int ctr = 0;
4752 int Yields = 0;
4753 for (;;) {
4754 while (*adr != 0) {
4755 ++ctr;
4756 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4757 if (Yields > 5) {
4758 os::naked_short_sleep(1);
4759 } else {
4760 os::naked_yield();
4761 ++Yields;
4762 }
4763 } else {
4764 SpinPause();
4765 }
4766 }
4767 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4768 }
4769 }
4770
4771 void Thread::SpinRelease(volatile int * adr) {
4772 assert(*adr != 0, "invariant");
4773 OrderAccess::fence(); // guarantee at least release consistency.
4774 // Roach-motel semantics.
4775 // It's safe if subsequent LDs and STs float "up" into the critical section,
4776 // but prior LDs and STs within the critical section can't be allowed
4777 // to reorder or float past the ST that releases the lock.
4778 // Loads and stores in the critical section - which appear in program
4779 // order before the store that releases the lock - must also appear
4780 // before the store that releases the lock in memory visibility order.
4781 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4782 // the ST of 0 into the lock-word which releases the lock, so fence
4783 // more than covers this on all platforms.
4784 *adr = 0;
4785 }
4786
4787 // muxAcquire and muxRelease:
4788 //
4789 // * muxAcquire and muxRelease support a single-word lock-word construct.
4790 // The LSB of the word is set IFF the lock is held.
4791 // The remainder of the word points to the head of a singly-linked list
4792 // of threads blocked on the lock.
4793 //
4794 // * The current implementation of muxAcquire-muxRelease uses its own
4795 // dedicated Thread._MuxEvent instance. If we're interested in
4796 // minimizing the peak number of extant ParkEvent instances then
4797 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4798 // as certain invariants were satisfied. Specifically, care would need
4799 // to be taken with regards to consuming unpark() "permits".
4800 // A safe rule of thumb is that a thread would never call muxAcquire()
4801 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4802 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4803 // consume an unpark() permit intended for monitorenter, for instance.
4804 // One way around this would be to widen the restricted-range semaphore
4805 // implemented in park(). Another alternative would be to provide
4806 // multiple instances of the PlatformEvent() for each thread. One
4807 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4808 //
4809 // * Usage:
4810 // -- Only as leaf locks
4811 // -- for short-term locking only as muxAcquire does not perform
4812 // thread state transitions.
4813 //
4814 // Alternatives:
4815 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4816 // but with parking or spin-then-park instead of pure spinning.
4817 // * Use Taura-Oyama-Yonenzawa locks.
4818 // * It's possible to construct a 1-0 lock if we encode the lockword as
4819 // (List,LockByte). Acquire will CAS the full lockword while Release
4820 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4821 // acquiring threads use timers (ParkTimed) to detect and recover from
4822 // the stranding window. Thread/Node structures must be aligned on 256-byte
4823 // boundaries by using placement-new.
4824 // * Augment MCS with advisory back-link fields maintained with CAS().
4825 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4826 // The validity of the backlinks must be ratified before we trust the value.
4827 // If the backlinks are invalid the exiting thread must back-track through the
4828 // the forward links, which are always trustworthy.
4829 // * Add a successor indication. The LockWord is currently encoded as
4830 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4831 // to provide the usual futile-wakeup optimization.
4832 // See RTStt for details.
4833 // * Consider schedctl.sc_nopreempt to cover the critical section.
4834 //
4835
4836
4837 const intptr_t LOCKBIT = 1;
4838
4839 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4840 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4841 if (w == 0) return;
4842 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4843 return;
4844 }
4845
4846 TEVENT(muxAcquire - Contention);
4847 ParkEvent * const Self = Thread::current()->_MuxEvent;
4848 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4849 for (;;) {
4850 int its = (os::is_MP() ? 100 : 0) + 1;
4851
4852 // Optional spin phase: spin-then-park strategy
4853 while (--its >= 0) {
4854 w = *Lock;
4855 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4856 return;
4857 }
4858 }
4859
4860 Self->reset();
4861 Self->OnList = intptr_t(Lock);
4862 // The following fence() isn't _strictly necessary as the subsequent
4863 // CAS() both serializes execution and ratifies the fetched *Lock value.
4864 OrderAccess::fence();
4865 for (;;) {
4866 w = *Lock;
4867 if ((w & LOCKBIT) == 0) {
4868 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4869 Self->OnList = 0; // hygiene - allows stronger asserts
4870 return;
4871 }
4872 continue; // Interference -- *Lock changed -- Just retry
4873 }
4874 assert(w & LOCKBIT, "invariant");
4875 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4876 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4877 }
4878
4879 while (Self->OnList != 0) {
4880 Self->park();
4881 }
4882 }
4883 }
4884
4885 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4886 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4887 if (w == 0) return;
4888 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4889 return;
4890 }
4891
4892 TEVENT(muxAcquire - Contention);
4893 ParkEvent * ReleaseAfter = NULL;
4894 if (ev == NULL) {
4895 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4896 }
4897 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4898 for (;;) {
4899 guarantee(ev->OnList == 0, "invariant");
4900 int its = (os::is_MP() ? 100 : 0) + 1;
4901
4902 // Optional spin phase: spin-then-park strategy
4903 while (--its >= 0) {
4904 w = *Lock;
4905 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4906 if (ReleaseAfter != NULL) {
4907 ParkEvent::Release(ReleaseAfter);
4908 }
4909 return;
4910 }
4911 }
4912
4913 ev->reset();
4914 ev->OnList = intptr_t(Lock);
4915 // The following fence() isn't _strictly necessary as the subsequent
4916 // CAS() both serializes execution and ratifies the fetched *Lock value.
4917 OrderAccess::fence();
4918 for (;;) {
4919 w = *Lock;
4920 if ((w & LOCKBIT) == 0) {
4921 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4922 ev->OnList = 0;
4923 // We call ::Release while holding the outer lock, thus
4924 // artificially lengthening the critical section.
4925 // Consider deferring the ::Release() until the subsequent unlock(),
4926 // after we've dropped the outer lock.
4927 if (ReleaseAfter != NULL) {
4928 ParkEvent::Release(ReleaseAfter);
4929 }
4930 return;
4931 }
4932 continue; // Interference -- *Lock changed -- Just retry
4933 }
4934 assert(w & LOCKBIT, "invariant");
4935 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4936 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4937 }
4938
4939 while (ev->OnList != 0) {
4940 ev->park();
4941 }
4942 }
4943 }
4944
4945 // Release() must extract a successor from the list and then wake that thread.
4946 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4947 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4948 // Release() would :
4949 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4950 // (B) Extract a successor from the private list "in-hand"
4951 // (C) attempt to CAS() the residual back into *Lock over null.
4952 // If there were any newly arrived threads and the CAS() would fail.
4953 // In that case Release() would detach the RATs, re-merge the list in-hand
4954 // with the RATs and repeat as needed. Alternately, Release() might
4955 // detach and extract a successor, but then pass the residual list to the wakee.
4956 // The wakee would be responsible for reattaching and remerging before it
4957 // competed for the lock.
4958 //
4959 // Both "pop" and DMR are immune from ABA corruption -- there can be
4960 // multiple concurrent pushers, but only one popper or detacher.
4961 // This implementation pops from the head of the list. This is unfair,
4962 // but tends to provide excellent throughput as hot threads remain hot.
4963 // (We wake recently run threads first).
4964 //
4965 // All paths through muxRelease() will execute a CAS.
4966 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4967 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4968 // executed within the critical section are complete and globally visible before the
4969 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4970 void Thread::muxRelease(volatile intptr_t * Lock) {
4971 for (;;) {
4972 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4973 assert(w & LOCKBIT, "invariant");
4974 if (w == LOCKBIT) return;
4975 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4976 assert(List != NULL, "invariant");
4977 assert(List->OnList == intptr_t(Lock), "invariant");
4978 ParkEvent * const nxt = List->ListNext;
4979 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4980
4981 // The following CAS() releases the lock and pops the head element.
4982 // The CAS() also ratifies the previously fetched lock-word value.
4983 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4984 continue;
4985 }
4986 List->OnList = 0;
4987 OrderAccess::fence();
4988 List->unpark();
4989 return;
4990 }
4991 }
4992
4993
4994 void Threads::verify() {
4995 ALL_JAVA_THREADS(p) {
4996 p->verify();
4997 }
4998 VMThread* thread = VMThread::vm_thread();
4999 if (thread != NULL) thread->verify();
5000 }