1 /*
2 * Copyright (c) 1997, 2015, 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 "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/scopeDesc.hpp"
32 #include "compiler/compileBroker.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "interpreter/linkResolver.hpp"
35 #include "interpreter/oopMapCache.hpp"
36 #include "jvmtifiles/jvmtiEnv.hpp"
37 #include "memory/gcLocker.inline.hpp"
38 #include "memory/metaspaceShared.hpp"
39 #include "memory/oopFactory.hpp"
40 #include "memory/universe.inline.hpp"
41 #include "oops/instanceKlass.hpp"
42 #include "oops/objArrayOop.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "oops/symbol.hpp"
45 #include "oops/verifyOopClosure.hpp"
46 #include "prims/jvm_misc.hpp"
47 #include "prims/jvmtiExport.hpp"
48 #include "prims/jvmtiThreadState.hpp"
49 #include "prims/privilegedStack.hpp"
50 #include "runtime/arguments.hpp"
51 #include "runtime/atomic.inline.hpp"
52 #include "runtime/biasedLocking.hpp"
53 #include "runtime/deoptimization.hpp"
54 #include "runtime/fprofiler.hpp"
55 #include "runtime/frame.inline.hpp"
56 #include "runtime/init.hpp"
57 #include "runtime/interfaceSupport.hpp"
58 #include "runtime/java.hpp"
59 #include "runtime/javaCalls.hpp"
60 #include "runtime/jniPeriodicChecker.hpp"
61 #include "runtime/memprofiler.hpp"
62 #include "runtime/mutexLocker.hpp"
63 #include "runtime/objectMonitor.hpp"
64 #include "runtime/orderAccess.inline.hpp"
65 #include "runtime/osThread.hpp"
66 #include "runtime/safepoint.hpp"
67 #include "runtime/sharedRuntime.hpp"
68 #include "runtime/statSampler.hpp"
69 #include "runtime/stubRoutines.hpp"
70 #include "runtime/sweeper.hpp"
71 #include "runtime/task.hpp"
72 #include "runtime/thread.inline.hpp"
73 #include "runtime/threadCritical.hpp"
74 #include "runtime/threadLocalStorage.hpp"
75 #include "runtime/vframe.hpp"
76 #include "runtime/vframeArray.hpp"
77 #include "runtime/vframe_hp.hpp"
78 #include "runtime/vmThread.hpp"
79 #include "runtime/vm_operations.hpp"
80 #include "runtime/vm_version.hpp"
81 #include "services/attachListener.hpp"
82 #include "services/management.hpp"
83 #include "services/memTracker.hpp"
84 #include "services/threadService.hpp"
85 #include "trace/tracing.hpp"
86 #include "trace/traceMacros.hpp"
87 #include "utilities/defaultStream.hpp"
88 #include "utilities/dtrace.hpp"
89 #include "utilities/events.hpp"
90 #include "utilities/preserveException.hpp"
91 #include "utilities/macros.hpp"
92 #if INCLUDE_ALL_GCS
93 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
94 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
95 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
96 #endif // INCLUDE_ALL_GCS
97 #ifdef COMPILER1
98 #include "c1/c1_Compiler.hpp"
99 #endif
100 #ifdef COMPILER2
101 #include "opto/c2compiler.hpp"
102 #include "opto/idealGraphPrinter.hpp"
103 #endif
104 #if INCLUDE_RTM_OPT
105 #include "runtime/rtmLocking.hpp"
106 #endif
107
108 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
109
110 #ifdef DTRACE_ENABLED
111
112 // Only bother with this argument setup if dtrace is available
113
114 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
115 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
116
117 #define DTRACE_THREAD_PROBE(probe, javathread) \
118 { \
119 ResourceMark rm(this); \
120 int len = 0; \
121 const char* name = (javathread)->get_thread_name(); \
122 len = strlen(name); \
123 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
124 (char *) name, len, \
125 java_lang_Thread::thread_id((javathread)->threadObj()), \
126 (uintptr_t) (javathread)->osthread()->thread_id(), \
127 java_lang_Thread::is_daemon((javathread)->threadObj())); \
128 }
129
130 #else // ndef DTRACE_ENABLED
131
132 #define DTRACE_THREAD_PROBE(probe, javathread)
133
134 #endif // ndef DTRACE_ENABLED
135
136
137 // Class hierarchy
138 // - Thread
139 // - VMThread
140 // - WatcherThread
141 // - ConcurrentMarkSweepThread
142 // - JavaThread
143 // - CompilerThread
144
145 // ======= Thread ========
146 // Support for forcing alignment of thread objects for biased locking
147 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
148 if (UseBiasedLocking) {
149 const int alignment = markOopDesc::biased_lock_alignment;
150 size_t aligned_size = size + (alignment - sizeof(intptr_t));
151 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
152 : AllocateHeap(aligned_size, flags, CURRENT_PC,
153 AllocFailStrategy::RETURN_NULL);
154 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
155 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
156 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
157 "JavaThread alignment code overflowed allocated storage");
158 if (TraceBiasedLocking) {
159 if (aligned_addr != real_malloc_addr) {
160 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
161 real_malloc_addr, aligned_addr);
162 }
163 }
164 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
165 return aligned_addr;
166 } else {
167 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
168 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
169 }
170 }
171
172 void Thread::operator delete(void* p) {
173 if (UseBiasedLocking) {
174 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
175 FreeHeap(real_malloc_addr);
176 } else {
177 FreeHeap(p);
178 }
179 }
180
181
182 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
183 // JavaThread
184
185
186 Thread::Thread() {
187 // stack and get_thread
188 set_stack_base(NULL);
189 set_stack_size(0);
190 set_self_raw_id(0);
191 set_lgrp_id(-1);
192
193 // allocated data structures
194 set_osthread(NULL);
195 set_resource_area(new (mtThread)ResourceArea());
196 DEBUG_ONLY(_current_resource_mark = NULL;)
197 set_handle_area(new (mtThread) HandleArea(NULL));
198 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
199 set_active_handles(NULL);
200 set_free_handle_block(NULL);
201 set_last_handle_mark(NULL);
202
203 // This initial value ==> never claimed.
204 _oops_do_parity = 0;
205
206 _metadata_on_stack_buffer = NULL;
207
208 // the handle mark links itself to last_handle_mark
209 new HandleMark(this);
210
211 // plain initialization
212 debug_only(_owned_locks = NULL;)
213 debug_only(_allow_allocation_count = 0;)
214 NOT_PRODUCT(_allow_safepoint_count = 0;)
215 NOT_PRODUCT(_skip_gcalot = false;)
216 _jvmti_env_iteration_count = 0;
217 set_allocated_bytes(0);
218 _vm_operation_started_count = 0;
219 _vm_operation_completed_count = 0;
220 _current_pending_monitor = NULL;
221 _current_pending_monitor_is_from_java = true;
222 _current_waiting_monitor = NULL;
223 _num_nested_signal = 0;
224 omFreeList = NULL;
225 omFreeCount = 0;
226 omFreeProvision = 32;
227 omInUseList = NULL;
228 omInUseCount = 0;
229
230 #ifdef ASSERT
231 _visited_for_critical_count = false;
232 #endif
233
234 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
235 Monitor::_safepoint_check_sometimes);
236 _suspend_flags = 0;
237
238 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
239 _hashStateX = os::random();
240 _hashStateY = 842502087;
241 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
242 _hashStateW = 273326509;
243
244 _OnTrap = 0;
245 _schedctl = NULL;
246 _Stalled = 0;
247 _TypeTag = 0x2BAD;
248
249 // Many of the following fields are effectively final - immutable
250 // Note that nascent threads can't use the Native Monitor-Mutex
251 // construct until the _MutexEvent is initialized ...
252 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
253 // we might instead use a stack of ParkEvents that we could provision on-demand.
254 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
255 // and ::Release()
256 _ParkEvent = ParkEvent::Allocate(this);
257 _SleepEvent = ParkEvent::Allocate(this);
258 _MutexEvent = ParkEvent::Allocate(this);
259 _MuxEvent = ParkEvent::Allocate(this);
260
261 #ifdef CHECK_UNHANDLED_OOPS
262 if (CheckUnhandledOops) {
263 _unhandled_oops = new UnhandledOops(this);
264 }
265 #endif // CHECK_UNHANDLED_OOPS
266 #ifdef ASSERT
267 if (UseBiasedLocking) {
268 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
269 assert(this == _real_malloc_address ||
270 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
271 "bug in forced alignment of thread objects");
272 }
273 #endif // ASSERT
274 }
275
276 void Thread::initialize_thread_local_storage() {
277 // Note: Make sure this method only calls
278 // non-blocking operations. Otherwise, it might not work
279 // with the thread-startup/safepoint interaction.
280
281 // During Java thread startup, safepoint code should allow this
282 // method to complete because it may need to allocate memory to
283 // store information for the new thread.
284
285 // initialize structure dependent on thread local storage
286 ThreadLocalStorage::set_thread(this);
287 }
288
289 void Thread::record_stack_base_and_size() {
290 set_stack_base(os::current_stack_base());
291 set_stack_size(os::current_stack_size());
292 if (is_Java_thread()) {
293 ((JavaThread*) this)->set_stack_overflow_limit();
294 }
295 // CR 7190089: on Solaris, primordial thread's stack is adjusted
296 // in initialize_thread(). Without the adjustment, stack size is
297 // incorrect if stack is set to unlimited (ulimit -s unlimited).
298 // So far, only Solaris has real implementation of initialize_thread().
299 //
300 // set up any platform-specific state.
301 os::initialize_thread(this);
302
303 #if INCLUDE_NMT
304 // record thread's native stack, stack grows downward
305 address stack_low_addr = stack_base() - stack_size();
306 MemTracker::record_thread_stack(stack_low_addr, stack_size());
307 #endif // INCLUDE_NMT
308 }
309
310
311 Thread::~Thread() {
312 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
313 ObjectSynchronizer::omFlush(this);
314
315 EVENT_THREAD_DESTRUCT(this);
316
317 // stack_base can be NULL if the thread is never started or exited before
318 // record_stack_base_and_size called. Although, we would like to ensure
319 // that all started threads do call record_stack_base_and_size(), there is
320 // not proper way to enforce that.
321 #if INCLUDE_NMT
322 if (_stack_base != NULL) {
323 address low_stack_addr = stack_base() - stack_size();
324 MemTracker::release_thread_stack(low_stack_addr, stack_size());
325 #ifdef ASSERT
326 set_stack_base(NULL);
327 #endif
328 }
329 #endif // INCLUDE_NMT
330
331 // deallocate data structures
332 delete resource_area();
333 // since the handle marks are using the handle area, we have to deallocated the root
334 // handle mark before deallocating the thread's handle area,
335 assert(last_handle_mark() != NULL, "check we have an element");
336 delete last_handle_mark();
337 assert(last_handle_mark() == NULL, "check we have reached the end");
338
339 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
340 // We NULL out the fields for good hygiene.
341 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
342 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
343 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
344 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
345
346 delete handle_area();
347 delete metadata_handles();
348
349 // osthread() can be NULL, if creation of thread failed.
350 if (osthread() != NULL) os::free_thread(osthread());
351
352 delete _SR_lock;
353
354 // clear thread local storage if the Thread is deleting itself
355 if (this == Thread::current()) {
356 ThreadLocalStorage::set_thread(NULL);
357 } else {
358 // In the case where we're not the current thread, invalidate all the
359 // caches in case some code tries to get the current thread or the
360 // thread that was destroyed, and gets stale information.
361 ThreadLocalStorage::invalidate_all();
362 }
363 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
364 }
365
366 // NOTE: dummy function for assertion purpose.
367 void Thread::run() {
368 ShouldNotReachHere();
369 }
370
371 #ifdef ASSERT
372 // Private method to check for dangling thread pointer
373 void check_for_dangling_thread_pointer(Thread *thread) {
374 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
375 "possibility of dangling Thread pointer");
376 }
377 #endif
378
379 ThreadPriority Thread::get_priority(const Thread* const thread) {
380 ThreadPriority priority;
381 // Can return an error!
382 (void)os::get_priority(thread, priority);
383 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
384 return priority;
385 }
386
387 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
388 debug_only(check_for_dangling_thread_pointer(thread);)
389 // Can return an error!
390 (void)os::set_priority(thread, priority);
391 }
392
393
394 void Thread::start(Thread* thread) {
395 // Start is different from resume in that its safety is guaranteed by context or
396 // being called from a Java method synchronized on the Thread object.
397 if (!DisableStartThread) {
398 if (thread->is_Java_thread()) {
399 // Initialize the thread state to RUNNABLE before starting this thread.
400 // Can not set it after the thread started because we do not know the
401 // exact thread state at that time. It could be in MONITOR_WAIT or
402 // in SLEEPING or some other state.
403 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
404 java_lang_Thread::RUNNABLE);
405 }
406 os::start_thread(thread);
407 }
408 }
409
410 // Enqueue a VM_Operation to do the job for us - sometime later
411 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
412 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
413 VMThread::execute(vm_stop);
414 }
415
416
417 // Check if an external suspend request has completed (or has been
418 // cancelled). Returns true if the thread is externally suspended and
419 // false otherwise.
420 //
421 // The bits parameter returns information about the code path through
422 // the routine. Useful for debugging:
423 //
424 // set in is_ext_suspend_completed():
425 // 0x00000001 - routine was entered
426 // 0x00000010 - routine return false at end
427 // 0x00000100 - thread exited (return false)
428 // 0x00000200 - suspend request cancelled (return false)
429 // 0x00000400 - thread suspended (return true)
430 // 0x00001000 - thread is in a suspend equivalent state (return true)
431 // 0x00002000 - thread is native and walkable (return true)
432 // 0x00004000 - thread is native_trans and walkable (needed retry)
433 //
434 // set in wait_for_ext_suspend_completion():
435 // 0x00010000 - routine was entered
436 // 0x00020000 - suspend request cancelled before loop (return false)
437 // 0x00040000 - thread suspended before loop (return true)
438 // 0x00080000 - suspend request cancelled in loop (return false)
439 // 0x00100000 - thread suspended in loop (return true)
440 // 0x00200000 - suspend not completed during retry loop (return false)
441
442 // Helper class for tracing suspend wait debug bits.
443 //
444 // 0x00000100 indicates that the target thread exited before it could
445 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
446 // 0x00080000 each indicate a cancelled suspend request so they don't
447 // count as wait failures either.
448 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
449
450 class TraceSuspendDebugBits : public StackObj {
451 private:
452 JavaThread * jt;
453 bool is_wait;
454 bool called_by_wait; // meaningful when !is_wait
455 uint32_t * bits;
456
457 public:
458 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
459 uint32_t *_bits) {
460 jt = _jt;
461 is_wait = _is_wait;
462 called_by_wait = _called_by_wait;
463 bits = _bits;
464 }
465
466 ~TraceSuspendDebugBits() {
467 if (!is_wait) {
468 #if 1
469 // By default, don't trace bits for is_ext_suspend_completed() calls.
470 // That trace is very chatty.
471 return;
472 #else
473 if (!called_by_wait) {
474 // If tracing for is_ext_suspend_completed() is enabled, then only
475 // trace calls to it from wait_for_ext_suspend_completion()
476 return;
477 }
478 #endif
479 }
480
481 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
482 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
483 MutexLocker ml(Threads_lock); // needed for get_thread_name()
484 ResourceMark rm;
485
486 tty->print_cr(
487 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
488 jt->get_thread_name(), *bits);
489
490 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
491 }
492 }
493 }
494 };
495 #undef DEBUG_FALSE_BITS
496
497
498 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
499 uint32_t *bits) {
500 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
501
502 bool did_trans_retry = false; // only do thread_in_native_trans retry once
503 bool do_trans_retry; // flag to force the retry
504
505 *bits |= 0x00000001;
506
507 do {
508 do_trans_retry = false;
509
510 if (is_exiting()) {
511 // Thread is in the process of exiting. This is always checked
512 // first to reduce the risk of dereferencing a freed JavaThread.
513 *bits |= 0x00000100;
514 return false;
515 }
516
517 if (!is_external_suspend()) {
518 // Suspend request is cancelled. This is always checked before
519 // is_ext_suspended() to reduce the risk of a rogue resume
520 // confusing the thread that made the suspend request.
521 *bits |= 0x00000200;
522 return false;
523 }
524
525 if (is_ext_suspended()) {
526 // thread is suspended
527 *bits |= 0x00000400;
528 return true;
529 }
530
531 // Now that we no longer do hard suspends of threads running
532 // native code, the target thread can be changing thread state
533 // while we are in this routine:
534 //
535 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
536 //
537 // We save a copy of the thread state as observed at this moment
538 // and make our decision about suspend completeness based on the
539 // copy. This closes the race where the thread state is seen as
540 // _thread_in_native_trans in the if-thread_blocked check, but is
541 // seen as _thread_blocked in if-thread_in_native_trans check.
542 JavaThreadState save_state = thread_state();
543
544 if (save_state == _thread_blocked && is_suspend_equivalent()) {
545 // If the thread's state is _thread_blocked and this blocking
546 // condition is known to be equivalent to a suspend, then we can
547 // consider the thread to be externally suspended. This means that
548 // the code that sets _thread_blocked has been modified to do
549 // self-suspension if the blocking condition releases. We also
550 // used to check for CONDVAR_WAIT here, but that is now covered by
551 // the _thread_blocked with self-suspension check.
552 //
553 // Return true since we wouldn't be here unless there was still an
554 // external suspend request.
555 *bits |= 0x00001000;
556 return true;
557 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
558 // Threads running native code will self-suspend on native==>VM/Java
559 // transitions. If its stack is walkable (should always be the case
560 // unless this function is called before the actual java_suspend()
561 // call), then the wait is done.
562 *bits |= 0x00002000;
563 return true;
564 } else if (!called_by_wait && !did_trans_retry &&
565 save_state == _thread_in_native_trans &&
566 frame_anchor()->walkable()) {
567 // The thread is transitioning from thread_in_native to another
568 // thread state. check_safepoint_and_suspend_for_native_trans()
569 // will force the thread to self-suspend. If it hasn't gotten
570 // there yet we may have caught the thread in-between the native
571 // code check above and the self-suspend. Lucky us. If we were
572 // called by wait_for_ext_suspend_completion(), then it
573 // will be doing the retries so we don't have to.
574 //
575 // Since we use the saved thread state in the if-statement above,
576 // there is a chance that the thread has already transitioned to
577 // _thread_blocked by the time we get here. In that case, we will
578 // make a single unnecessary pass through the logic below. This
579 // doesn't hurt anything since we still do the trans retry.
580
581 *bits |= 0x00004000;
582
583 // Once the thread leaves thread_in_native_trans for another
584 // thread state, we break out of this retry loop. We shouldn't
585 // need this flag to prevent us from getting back here, but
586 // sometimes paranoia is good.
587 did_trans_retry = true;
588
589 // We wait for the thread to transition to a more usable state.
590 for (int i = 1; i <= SuspendRetryCount; i++) {
591 // We used to do an "os::yield_all(i)" call here with the intention
592 // that yielding would increase on each retry. However, the parameter
593 // is ignored on Linux which means the yield didn't scale up. Waiting
594 // on the SR_lock below provides a much more predictable scale up for
595 // the delay. It also provides a simple/direct point to check for any
596 // safepoint requests from the VMThread
597
598 // temporarily drops SR_lock while doing wait with safepoint check
599 // (if we're a JavaThread - the WatcherThread can also call this)
600 // and increase delay with each retry
601 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
602
603 // check the actual thread state instead of what we saved above
604 if (thread_state() != _thread_in_native_trans) {
605 // the thread has transitioned to another thread state so
606 // try all the checks (except this one) one more time.
607 do_trans_retry = true;
608 break;
609 }
610 } // end retry loop
611
612
613 }
614 } while (do_trans_retry);
615
616 *bits |= 0x00000010;
617 return false;
618 }
619
620 // Wait for an external suspend request to complete (or be cancelled).
621 // Returns true if the thread is externally suspended and false otherwise.
622 //
623 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
624 uint32_t *bits) {
625 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
626 false /* !called_by_wait */, bits);
627
628 // local flag copies to minimize SR_lock hold time
629 bool is_suspended;
630 bool pending;
631 uint32_t reset_bits;
632
633 // set a marker so is_ext_suspend_completed() knows we are the caller
634 *bits |= 0x00010000;
635
636 // We use reset_bits to reinitialize the bits value at the top of
637 // each retry loop. This allows the caller to make use of any
638 // unused bits for their own marking purposes.
639 reset_bits = *bits;
640
641 {
642 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
643 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
644 delay, bits);
645 pending = is_external_suspend();
646 }
647 // must release SR_lock to allow suspension to complete
648
649 if (!pending) {
650 // A cancelled suspend request is the only false return from
651 // is_ext_suspend_completed() that keeps us from entering the
652 // retry loop.
653 *bits |= 0x00020000;
654 return false;
655 }
656
657 if (is_suspended) {
658 *bits |= 0x00040000;
659 return true;
660 }
661
662 for (int i = 1; i <= retries; i++) {
663 *bits = reset_bits; // reinit to only track last retry
664
665 // We used to do an "os::yield_all(i)" call here with the intention
666 // that yielding would increase on each retry. However, the parameter
667 // is ignored on Linux which means the yield didn't scale up. Waiting
668 // on the SR_lock below provides a much more predictable scale up for
669 // the delay. It also provides a simple/direct point to check for any
670 // safepoint requests from the VMThread
671
672 {
673 MutexLocker ml(SR_lock());
674 // wait with safepoint check (if we're a JavaThread - the WatcherThread
675 // can also call this) and increase delay with each retry
676 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
677
678 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
679 delay, bits);
680
681 // It is possible for the external suspend request to be cancelled
682 // (by a resume) before the actual suspend operation is completed.
683 // Refresh our local copy to see if we still need to wait.
684 pending = is_external_suspend();
685 }
686
687 if (!pending) {
688 // A cancelled suspend request is the only false return from
689 // is_ext_suspend_completed() that keeps us from staying in the
690 // retry loop.
691 *bits |= 0x00080000;
692 return false;
693 }
694
695 if (is_suspended) {
696 *bits |= 0x00100000;
697 return true;
698 }
699 } // end retry loop
700
701 // thread did not suspend after all our retries
702 *bits |= 0x00200000;
703 return false;
704 }
705
706 #ifndef PRODUCT
707 void JavaThread::record_jump(address target, address instr, const char* file,
708 int line) {
709
710 // This should not need to be atomic as the only way for simultaneous
711 // updates is via interrupts. Even then this should be rare or non-existent
712 // and we don't care that much anyway.
713
714 int index = _jmp_ring_index;
715 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
716 _jmp_ring[index]._target = (intptr_t) target;
717 _jmp_ring[index]._instruction = (intptr_t) instr;
718 _jmp_ring[index]._file = file;
719 _jmp_ring[index]._line = line;
720 }
721 #endif // PRODUCT
722
723 // Called by flat profiler
724 // Callers have already called wait_for_ext_suspend_completion
725 // The assertion for that is currently too complex to put here:
726 bool JavaThread::profile_last_Java_frame(frame* _fr) {
727 bool gotframe = false;
728 // self suspension saves needed state.
729 if (has_last_Java_frame() && _anchor.walkable()) {
730 *_fr = pd_last_frame();
731 gotframe = true;
732 }
733 return gotframe;
734 }
735
736 void Thread::interrupt(Thread* thread) {
737 debug_only(check_for_dangling_thread_pointer(thread);)
738 os::interrupt(thread);
739 }
740
741 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
742 debug_only(check_for_dangling_thread_pointer(thread);)
743 // Note: If clear_interrupted==false, this simply fetches and
744 // returns the value of the field osthread()->interrupted().
745 return os::is_interrupted(thread, clear_interrupted);
746 }
747
748
749 // GC Support
750 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
751 jint thread_parity = _oops_do_parity;
752 if (thread_parity != strong_roots_parity) {
753 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
754 if (res == thread_parity) {
755 return true;
756 } else {
757 guarantee(res == strong_roots_parity, "Or else what?");
758 assert(SharedHeap::heap()->workers()->active_workers() > 0,
759 "Should only fail when parallel.");
760 return false;
761 }
762 }
763 assert(SharedHeap::heap()->workers()->active_workers() > 0,
764 "Should only fail when parallel.");
765 return false;
766 }
767
768 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
769 active_handles()->oops_do(f);
770 // Do oop for ThreadShadow
771 f->do_oop((oop*)&_pending_exception);
772 handle_area()->oops_do(f);
773 }
774
775 void Thread::nmethods_do(CodeBlobClosure* cf) {
776 // no nmethods in a generic thread...
777 }
778
779 void Thread::metadata_do(void f(Metadata*)) {
780 if (metadata_handles() != NULL) {
781 for (int i = 0; i< metadata_handles()->length(); i++) {
782 f(metadata_handles()->at(i));
783 }
784 }
785 }
786
787 void Thread::print_on(outputStream* st) const {
788 // get_priority assumes osthread initialized
789 if (osthread() != NULL) {
790 int os_prio;
791 if (os::get_native_priority(this, &os_prio) == OS_OK) {
792 st->print("os_prio=%d ", os_prio);
793 }
794 st->print("tid=" INTPTR_FORMAT " ", this);
795 ext().print_on(st);
796 osthread()->print_on(st);
797 }
798 debug_only(if (WizardMode) print_owned_locks_on(st);)
799 }
800
801 // Thread::print_on_error() is called by fatal error handler. Don't use
802 // any lock or allocate memory.
803 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
804 if (is_VM_thread()) st->print("VMThread");
805 else if (is_Compiler_thread()) st->print("CompilerThread");
806 else if (is_Java_thread()) st->print("JavaThread");
807 else if (is_GC_task_thread()) st->print("GCTaskThread");
808 else if (is_Watcher_thread()) st->print("WatcherThread");
809 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
810 else st->print("Thread");
811
812 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
813 _stack_base - _stack_size, _stack_base);
814
815 if (osthread()) {
816 st->print(" [id=%d]", osthread()->thread_id());
817 }
818 }
819
820 #ifdef ASSERT
821 void Thread::print_owned_locks_on(outputStream* st) const {
822 Monitor *cur = _owned_locks;
823 if (cur == NULL) {
824 st->print(" (no locks) ");
825 } else {
826 st->print_cr(" Locks owned:");
827 while (cur) {
828 cur->print_on(st);
829 cur = cur->next();
830 }
831 }
832 }
833
834 static int ref_use_count = 0;
835
836 bool Thread::owns_locks_but_compiled_lock() const {
837 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
838 if (cur != Compile_lock) return true;
839 }
840 return false;
841 }
842
843
844 #endif
845
846 #ifndef PRODUCT
847
848 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
849 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
850 // no threads which allow_vm_block's are held
851 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
852 // Check if current thread is allowed to block at a safepoint
853 if (!(_allow_safepoint_count == 0)) {
854 fatal("Possible safepoint reached by thread that does not allow it");
855 }
856 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
857 fatal("LEAF method calling lock?");
858 }
859
860 #ifdef ASSERT
861 if (potential_vm_operation && is_Java_thread()
862 && !Universe::is_bootstrapping()) {
863 // Make sure we do not hold any locks that the VM thread also uses.
864 // This could potentially lead to deadlocks
865 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
866 // Threads_lock is special, since the safepoint synchronization will not start before this is
867 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
868 // since it is used to transfer control between JavaThreads and the VMThread
869 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
870 if ((cur->allow_vm_block() &&
871 cur != Threads_lock &&
872 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
873 cur != VMOperationRequest_lock &&
874 cur != VMOperationQueue_lock) ||
875 cur->rank() == Mutex::special) {
876 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
877 }
878 }
879 }
880
881 if (GCALotAtAllSafepoints) {
882 // We could enter a safepoint here and thus have a gc
883 InterfaceSupport::check_gc_alot();
884 }
885 #endif
886 }
887 #endif
888
889 bool Thread::is_in_stack(address adr) const {
890 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
891 address end = os::current_stack_pointer();
892 // Allow non Java threads to call this without stack_base
893 if (_stack_base == NULL) return true;
894 if (stack_base() >= adr && adr >= end) return true;
895
896 return false;
897 }
898
899
900 bool Thread::is_in_usable_stack(address adr) const {
901 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
902 size_t usable_stack_size = _stack_size - stack_guard_size;
903
904 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
905 }
906
907
908 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
909 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
910 // used for compilation in the future. If that change is made, the need for these methods
911 // should be revisited, and they should be removed if possible.
912
913 bool Thread::is_lock_owned(address adr) const {
914 return on_local_stack(adr);
915 }
916
917 bool Thread::set_as_starting_thread() {
918 // NOTE: this must be called inside the main thread.
919 return os::create_main_thread((JavaThread*)this);
920 }
921
922 static void initialize_class(Symbol* class_name, TRAPS) {
923 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
924 InstanceKlass::cast(klass)->initialize(CHECK);
925 }
926
927
928 // Creates the initial ThreadGroup
929 static Handle create_initial_thread_group(TRAPS) {
930 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
931 instanceKlassHandle klass (THREAD, k);
932
933 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
934 {
935 JavaValue result(T_VOID);
936 JavaCalls::call_special(&result,
937 system_instance,
938 klass,
939 vmSymbols::object_initializer_name(),
940 vmSymbols::void_method_signature(),
941 CHECK_NH);
942 }
943 Universe::set_system_thread_group(system_instance());
944
945 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
946 {
947 JavaValue result(T_VOID);
948 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
949 JavaCalls::call_special(&result,
950 main_instance,
951 klass,
952 vmSymbols::object_initializer_name(),
953 vmSymbols::threadgroup_string_void_signature(),
954 system_instance,
955 string,
956 CHECK_NH);
957 }
958 return main_instance;
959 }
960
961 // Creates the initial Thread
962 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
963 TRAPS) {
964 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
965 instanceKlassHandle klass (THREAD, k);
966 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
967
968 java_lang_Thread::set_thread(thread_oop(), thread);
969 java_lang_Thread::set_priority(thread_oop(), NormPriority);
970 thread->set_threadObj(thread_oop());
971
972 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
973
974 JavaValue result(T_VOID);
975 JavaCalls::call_special(&result, thread_oop,
976 klass,
977 vmSymbols::object_initializer_name(),
978 vmSymbols::threadgroup_string_void_signature(),
979 thread_group,
980 string,
981 CHECK_NULL);
982 return thread_oop();
983 }
984
985 static void call_initializeSystemClass(TRAPS) {
986 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
987 instanceKlassHandle klass (THREAD, k);
988
989 JavaValue result(T_VOID);
990 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
991 vmSymbols::void_method_signature(), CHECK);
992 }
993
994 char java_runtime_name[128] = "";
995 char java_runtime_version[128] = "";
996
997 // extract the JRE name from sun.misc.Version.java_runtime_name
998 static const char* get_java_runtime_name(TRAPS) {
999 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1000 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1001 fieldDescriptor fd;
1002 bool found = k != NULL &&
1003 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1004 vmSymbols::string_signature(), &fd);
1005 if (found) {
1006 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1007 if (name_oop == NULL) {
1008 return NULL;
1009 }
1010 const char* name = java_lang_String::as_utf8_string(name_oop,
1011 java_runtime_name,
1012 sizeof(java_runtime_name));
1013 return name;
1014 } else {
1015 return NULL;
1016 }
1017 }
1018
1019 // extract the JRE version from sun.misc.Version.java_runtime_version
1020 static const char* get_java_runtime_version(TRAPS) {
1021 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1022 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1023 fieldDescriptor fd;
1024 bool found = k != NULL &&
1025 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1026 vmSymbols::string_signature(), &fd);
1027 if (found) {
1028 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1029 if (name_oop == NULL) {
1030 return NULL;
1031 }
1032 const char* name = java_lang_String::as_utf8_string(name_oop,
1033 java_runtime_version,
1034 sizeof(java_runtime_version));
1035 return name;
1036 } else {
1037 return NULL;
1038 }
1039 }
1040
1041 // General purpose hook into Java code, run once when the VM is initialized.
1042 // The Java library method itself may be changed independently from the VM.
1043 static void call_postVMInitHook(TRAPS) {
1044 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1045 instanceKlassHandle klass (THREAD, k);
1046 if (klass.not_null()) {
1047 JavaValue result(T_VOID);
1048 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1049 vmSymbols::void_method_signature(),
1050 CHECK);
1051 }
1052 }
1053
1054 static void reset_vm_info_property(TRAPS) {
1055 // the vm info string
1056 ResourceMark rm(THREAD);
1057 const char *vm_info = VM_Version::vm_info_string();
1058
1059 // java.lang.System class
1060 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1061 instanceKlassHandle klass (THREAD, k);
1062
1063 // setProperty arguments
1064 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1065 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1066
1067 // return value
1068 JavaValue r(T_OBJECT);
1069
1070 // public static String setProperty(String key, String value);
1071 JavaCalls::call_static(&r,
1072 klass,
1073 vmSymbols::setProperty_name(),
1074 vmSymbols::string_string_string_signature(),
1075 key_str,
1076 value_str,
1077 CHECK);
1078 }
1079
1080
1081 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1082 bool daemon, TRAPS) {
1083 assert(thread_group.not_null(), "thread group should be specified");
1084 assert(threadObj() == NULL, "should only create Java thread object once");
1085
1086 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1087 instanceKlassHandle klass (THREAD, k);
1088 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1089
1090 java_lang_Thread::set_thread(thread_oop(), this);
1091 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1092 set_threadObj(thread_oop());
1093
1094 JavaValue result(T_VOID);
1095 if (thread_name != NULL) {
1096 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1097 // Thread gets assigned specified name and null target
1098 JavaCalls::call_special(&result,
1099 thread_oop,
1100 klass,
1101 vmSymbols::object_initializer_name(),
1102 vmSymbols::threadgroup_string_void_signature(),
1103 thread_group, // Argument 1
1104 name, // Argument 2
1105 THREAD);
1106 } else {
1107 // Thread gets assigned name "Thread-nnn" and null target
1108 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1109 JavaCalls::call_special(&result,
1110 thread_oop,
1111 klass,
1112 vmSymbols::object_initializer_name(),
1113 vmSymbols::threadgroup_runnable_void_signature(),
1114 thread_group, // Argument 1
1115 Handle(), // Argument 2
1116 THREAD);
1117 }
1118
1119
1120 if (daemon) {
1121 java_lang_Thread::set_daemon(thread_oop());
1122 }
1123
1124 if (HAS_PENDING_EXCEPTION) {
1125 return;
1126 }
1127
1128 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1129 Handle threadObj(THREAD, this->threadObj());
1130
1131 JavaCalls::call_special(&result,
1132 thread_group,
1133 group,
1134 vmSymbols::add_method_name(),
1135 vmSymbols::thread_void_signature(),
1136 threadObj, // Arg 1
1137 THREAD);
1138 }
1139
1140 // NamedThread -- non-JavaThread subclasses with multiple
1141 // uniquely named instances should derive from this.
1142 NamedThread::NamedThread() : Thread() {
1143 _name = NULL;
1144 _processed_thread = NULL;
1145 }
1146
1147 NamedThread::~NamedThread() {
1148 if (_name != NULL) {
1149 FREE_C_HEAP_ARRAY(char, _name);
1150 _name = NULL;
1151 }
1152 }
1153
1154 void NamedThread::set_name(const char* format, ...) {
1155 guarantee(_name == NULL, "Only get to set name once.");
1156 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1157 guarantee(_name != NULL, "alloc failure");
1158 va_list ap;
1159 va_start(ap, format);
1160 jio_vsnprintf(_name, max_name_len, format, ap);
1161 va_end(ap);
1162 }
1163
1164 void NamedThread::print_on(outputStream* st) const {
1165 st->print("\"%s\" ", name());
1166 Thread::print_on(st);
1167 st->cr();
1168 }
1169
1170
1171 // ======= WatcherThread ========
1172
1173 // The watcher thread exists to simulate timer interrupts. It should
1174 // be replaced by an abstraction over whatever native support for
1175 // timer interrupts exists on the platform.
1176
1177 WatcherThread* WatcherThread::_watcher_thread = NULL;
1178 bool WatcherThread::_startable = false;
1179 volatile bool WatcherThread::_should_terminate = false;
1180
1181 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1182 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1183 if (os::create_thread(this, os::watcher_thread)) {
1184 _watcher_thread = this;
1185
1186 // Set the watcher thread to the highest OS priority which should not be
1187 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1188 // is created. The only normal thread using this priority is the reference
1189 // handler thread, which runs for very short intervals only.
1190 // If the VMThread's priority is not lower than the WatcherThread profiling
1191 // will be inaccurate.
1192 os::set_priority(this, MaxPriority);
1193 if (!DisableStartThread) {
1194 os::start_thread(this);
1195 }
1196 }
1197 }
1198
1199 int WatcherThread::sleep() const {
1200 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1201
1202 // remaining will be zero if there are no tasks,
1203 // causing the WatcherThread to sleep until a task is
1204 // enrolled
1205 int remaining = PeriodicTask::time_to_wait();
1206 int time_slept = 0;
1207
1208 // we expect this to timeout - we only ever get unparked when
1209 // we should terminate or when a new task has been enrolled
1210 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1211
1212 jlong time_before_loop = os::javaTimeNanos();
1213
1214 for (;;) {
1215 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
1216 jlong now = os::javaTimeNanos();
1217
1218 if (remaining == 0) {
1219 // if we didn't have any tasks we could have waited for a long time
1220 // consider the time_slept zero and reset time_before_loop
1221 time_slept = 0;
1222 time_before_loop = now;
1223 } else {
1224 // need to recalculate since we might have new tasks in _tasks
1225 time_slept = (int) ((now - time_before_loop) / 1000000);
1226 }
1227
1228 // Change to task list or spurious wakeup of some kind
1229 if (timedout || _should_terminate) {
1230 break;
1231 }
1232
1233 remaining = PeriodicTask::time_to_wait();
1234 if (remaining == 0) {
1235 // Last task was just disenrolled so loop around and wait until
1236 // another task gets enrolled
1237 continue;
1238 }
1239
1240 remaining -= time_slept;
1241 if (remaining <= 0) {
1242 break;
1243 }
1244 }
1245
1246 return time_slept;
1247 }
1248
1249 void WatcherThread::run() {
1250 assert(this == watcher_thread(), "just checking");
1251
1252 this->record_stack_base_and_size();
1253 this->initialize_thread_local_storage();
1254 this->set_native_thread_name(this->name());
1255 this->set_active_handles(JNIHandleBlock::allocate_block());
1256 while (!_should_terminate) {
1257 assert(watcher_thread() == Thread::current(), "thread consistency check");
1258 assert(watcher_thread() == this, "thread consistency check");
1259
1260 // Calculate how long it'll be until the next PeriodicTask work
1261 // should be done, and sleep that amount of time.
1262 int time_waited = sleep();
1263
1264 if (is_error_reported()) {
1265 // A fatal error has happened, the error handler(VMError::report_and_die)
1266 // should abort JVM after creating an error log file. However in some
1267 // rare cases, the error handler itself might deadlock. Here we try to
1268 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1269 //
1270 // This code is in WatcherThread because WatcherThread wakes up
1271 // periodically so the fatal error handler doesn't need to do anything;
1272 // also because the WatcherThread is less likely to crash than other
1273 // threads.
1274
1275 for (;;) {
1276 if (!ShowMessageBoxOnError
1277 && (OnError == NULL || OnError[0] == '\0')
1278 && Arguments::abort_hook() == NULL) {
1279 os::sleep(this, 2 * 60 * 1000, false);
1280 fdStream err(defaultStream::output_fd());
1281 err.print_raw_cr("# [ timer expired, abort... ]");
1282 // skip atexit/vm_exit/vm_abort hooks
1283 os::die();
1284 }
1285
1286 // Wake up 5 seconds later, the fatal handler may reset OnError or
1287 // ShowMessageBoxOnError when it is ready to abort.
1288 os::sleep(this, 5 * 1000, false);
1289 }
1290 }
1291
1292 PeriodicTask::real_time_tick(time_waited);
1293 }
1294
1295 // Signal that it is terminated
1296 {
1297 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1298 _watcher_thread = NULL;
1299 Terminator_lock->notify();
1300 }
1301
1302 // Thread destructor usually does this..
1303 ThreadLocalStorage::set_thread(NULL);
1304 }
1305
1306 void WatcherThread::start() {
1307 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1308
1309 if (watcher_thread() == NULL && _startable) {
1310 _should_terminate = false;
1311 // Create the single instance of WatcherThread
1312 new WatcherThread();
1313 }
1314 }
1315
1316 void WatcherThread::make_startable() {
1317 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1318 _startable = true;
1319 }
1320
1321 void WatcherThread::stop() {
1322 // Get the PeriodicTask_lock if we can. If we cannot, then the
1323 // WatcherThread is using it and we don't want to block on that lock
1324 // here because that might cause a safepoint deadlock depending on
1325 // what the current WatcherThread tasks are doing.
1326 bool have_lock = PeriodicTask_lock->try_lock();
1327
1328 _should_terminate = true;
1329 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1330
1331 if (have_lock) {
1332 WatcherThread* watcher = watcher_thread();
1333 if (watcher != NULL) {
1334 // If we managed to get the lock, then we should unpark the
1335 // WatcherThread so that it can see we want it to stop.
1336 watcher->unpark();
1337 }
1338
1339 PeriodicTask_lock->unlock();
1340 }
1341
1342 // it is ok to take late safepoints here, if needed
1343 MutexLocker mu(Terminator_lock);
1344
1345 while (watcher_thread() != NULL) {
1346 // This wait should make safepoint checks, wait without a timeout,
1347 // and wait as a suspend-equivalent condition.
1348 //
1349 // Note: If the FlatProfiler is running, then this thread is waiting
1350 // for the WatcherThread to terminate and the WatcherThread, via the
1351 // FlatProfiler task, is waiting for the external suspend request on
1352 // this thread to complete. wait_for_ext_suspend_completion() will
1353 // eventually timeout, but that takes time. Making this wait a
1354 // suspend-equivalent condition solves that timeout problem.
1355 //
1356 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1357 Mutex::_as_suspend_equivalent_flag);
1358 }
1359 }
1360
1361 void WatcherThread::unpark() {
1362 MutexLockerEx ml(PeriodicTask_lock->owned_by_self()
1363 ? NULL
1364 : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1365 PeriodicTask_lock->notify();
1366 }
1367
1368 void WatcherThread::print_on(outputStream* st) const {
1369 st->print("\"%s\" ", name());
1370 Thread::print_on(st);
1371 st->cr();
1372 }
1373
1374 // ======= JavaThread ========
1375
1376 // A JavaThread is a normal Java thread
1377
1378 void JavaThread::initialize() {
1379 // Initialize fields
1380
1381 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1382 set_claimed_par_id(UINT_MAX);
1383
1384 set_saved_exception_pc(NULL);
1385 set_threadObj(NULL);
1386 _anchor.clear();
1387 set_entry_point(NULL);
1388 set_jni_functions(jni_functions());
1389 set_callee_target(NULL);
1390 set_vm_result(NULL);
1391 set_vm_result_2(NULL);
1392 set_vframe_array_head(NULL);
1393 set_vframe_array_last(NULL);
1394 set_deferred_locals(NULL);
1395 set_deopt_mark(NULL);
1396 set_deopt_nmethod(NULL);
1397 clear_must_deopt_id();
1398 set_monitor_chunks(NULL);
1399 set_next(NULL);
1400 set_thread_state(_thread_new);
1401 _terminated = _not_terminated;
1402 _privileged_stack_top = NULL;
1403 _array_for_gc = NULL;
1404 _suspend_equivalent = false;
1405 _in_deopt_handler = 0;
1406 _doing_unsafe_access = false;
1407 _stack_guard_state = stack_guard_unused;
1408 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1409 _exception_pc = 0;
1410 _exception_handler_pc = 0;
1411 _is_method_handle_return = 0;
1412 _jvmti_thread_state= NULL;
1413 _should_post_on_exceptions_flag = JNI_FALSE;
1414 _jvmti_get_loaded_classes_closure = NULL;
1415 _interp_only_mode = 0;
1416 _special_runtime_exit_condition = _no_async_condition;
1417 _pending_async_exception = NULL;
1418 _thread_stat = NULL;
1419 _thread_stat = new ThreadStatistics();
1420 _blocked_on_compilation = false;
1421 _jni_active_critical = 0;
1422 _pending_jni_exception_check_fn = NULL;
1423 _do_not_unlock_if_synchronized = false;
1424 _cached_monitor_info = NULL;
1425 _parker = Parker::Allocate(this);
1426
1427 #ifndef PRODUCT
1428 _jmp_ring_index = 0;
1429 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1430 record_jump(NULL, NULL, NULL, 0);
1431 }
1432 #endif // PRODUCT
1433
1434 set_thread_profiler(NULL);
1435 if (FlatProfiler::is_active()) {
1436 // This is where we would decide to either give each thread it's own profiler
1437 // or use one global one from FlatProfiler,
1438 // or up to some count of the number of profiled threads, etc.
1439 ThreadProfiler* pp = new ThreadProfiler();
1440 pp->engage();
1441 set_thread_profiler(pp);
1442 }
1443
1444 // Setup safepoint state info for this thread
1445 ThreadSafepointState::create(this);
1446
1447 debug_only(_java_call_counter = 0);
1448
1449 // JVMTI PopFrame support
1450 _popframe_condition = popframe_inactive;
1451 _popframe_preserved_args = NULL;
1452 _popframe_preserved_args_size = 0;
1453 _frames_to_pop_failed_realloc = 0;
1454
1455 pd_initialize();
1456 }
1457
1458 #if INCLUDE_ALL_GCS
1459 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1460 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1461 #endif // INCLUDE_ALL_GCS
1462
1463 JavaThread::JavaThread(bool is_attaching_via_jni) :
1464 Thread()
1465 #if INCLUDE_ALL_GCS
1466 , _satb_mark_queue(&_satb_mark_queue_set),
1467 _dirty_card_queue(&_dirty_card_queue_set)
1468 #endif // INCLUDE_ALL_GCS
1469 {
1470 initialize();
1471 if (is_attaching_via_jni) {
1472 _jni_attach_state = _attaching_via_jni;
1473 } else {
1474 _jni_attach_state = _not_attaching_via_jni;
1475 }
1476 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1477 }
1478
1479 bool JavaThread::reguard_stack(address cur_sp) {
1480 if (_stack_guard_state != stack_guard_yellow_disabled) {
1481 return true; // Stack already guarded or guard pages not needed.
1482 }
1483
1484 if (register_stack_overflow()) {
1485 // For those architectures which have separate register and
1486 // memory stacks, we must check the register stack to see if
1487 // it has overflowed.
1488 return false;
1489 }
1490
1491 // Java code never executes within the yellow zone: the latter is only
1492 // there to provoke an exception during stack banging. If java code
1493 // is executing there, either StackShadowPages should be larger, or
1494 // some exception code in c1, c2 or the interpreter isn't unwinding
1495 // when it should.
1496 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1497
1498 enable_stack_yellow_zone();
1499 return true;
1500 }
1501
1502 bool JavaThread::reguard_stack(void) {
1503 return reguard_stack(os::current_stack_pointer());
1504 }
1505
1506
1507 void JavaThread::block_if_vm_exited() {
1508 if (_terminated == _vm_exited) {
1509 // _vm_exited is set at safepoint, and Threads_lock is never released
1510 // we will block here forever
1511 Threads_lock->lock_without_safepoint_check();
1512 ShouldNotReachHere();
1513 }
1514 }
1515
1516
1517 // Remove this ifdef when C1 is ported to the compiler interface.
1518 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1519 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1520
1521 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1522 Thread()
1523 #if INCLUDE_ALL_GCS
1524 , _satb_mark_queue(&_satb_mark_queue_set),
1525 _dirty_card_queue(&_dirty_card_queue_set)
1526 #endif // INCLUDE_ALL_GCS
1527 {
1528 initialize();
1529 _jni_attach_state = _not_attaching_via_jni;
1530 set_entry_point(entry_point);
1531 // Create the native thread itself.
1532 // %note runtime_23
1533 os::ThreadType thr_type = os::java_thread;
1534 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1535 os::java_thread;
1536 os::create_thread(this, thr_type, stack_sz);
1537 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1538 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1539 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1540 // the exception consists of creating the exception object & initializing it, initialization
1541 // will leave the VM via a JavaCall and then all locks must be unlocked).
1542 //
1543 // The thread is still suspended when we reach here. Thread must be explicit started
1544 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1545 // by calling Threads:add. The reason why this is not done here, is because the thread
1546 // object must be fully initialized (take a look at JVM_Start)
1547 }
1548
1549 JavaThread::~JavaThread() {
1550
1551 // JSR166 -- return the parker to the free list
1552 Parker::Release(_parker);
1553 _parker = NULL;
1554
1555 // Free any remaining previous UnrollBlock
1556 vframeArray* old_array = vframe_array_last();
1557
1558 if (old_array != NULL) {
1559 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1560 old_array->set_unroll_block(NULL);
1561 delete old_info;
1562 delete old_array;
1563 }
1564
1565 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1566 if (deferred != NULL) {
1567 // This can only happen if thread is destroyed before deoptimization occurs.
1568 assert(deferred->length() != 0, "empty array!");
1569 do {
1570 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1571 deferred->remove_at(0);
1572 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1573 delete dlv;
1574 } while (deferred->length() != 0);
1575 delete deferred;
1576 }
1577
1578 // All Java related clean up happens in exit
1579 ThreadSafepointState::destroy(this);
1580 if (_thread_profiler != NULL) delete _thread_profiler;
1581 if (_thread_stat != NULL) delete _thread_stat;
1582 }
1583
1584
1585 // The first routine called by a new Java thread
1586 void JavaThread::run() {
1587 // initialize thread-local alloc buffer related fields
1588 this->initialize_tlab();
1589
1590 // used to test validity of stack trace backs
1591 this->record_base_of_stack_pointer();
1592
1593 // Record real stack base and size.
1594 this->record_stack_base_and_size();
1595
1596 // Initialize thread local storage; set before calling MutexLocker
1597 this->initialize_thread_local_storage();
1598
1599 this->create_stack_guard_pages();
1600
1601 this->cache_global_variables();
1602
1603 // Thread is now sufficient initialized to be handled by the safepoint code as being
1604 // in the VM. Change thread state from _thread_new to _thread_in_vm
1605 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1606
1607 assert(JavaThread::current() == this, "sanity check");
1608 assert(!Thread::current()->owns_locks(), "sanity check");
1609
1610 DTRACE_THREAD_PROBE(start, this);
1611
1612 // This operation might block. We call that after all safepoint checks for a new thread has
1613 // been completed.
1614 this->set_active_handles(JNIHandleBlock::allocate_block());
1615
1616 if (JvmtiExport::should_post_thread_life()) {
1617 JvmtiExport::post_thread_start(this);
1618 }
1619
1620 EventThreadStart event;
1621 if (event.should_commit()) {
1622 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1623 event.commit();
1624 }
1625
1626 // We call another function to do the rest so we are sure that the stack addresses used
1627 // from there will be lower than the stack base just computed
1628 thread_main_inner();
1629
1630 // Note, thread is no longer valid at this point!
1631 }
1632
1633
1634 void JavaThread::thread_main_inner() {
1635 assert(JavaThread::current() == this, "sanity check");
1636 assert(this->threadObj() != NULL, "just checking");
1637
1638 // Execute thread entry point unless this thread has a pending exception
1639 // or has been stopped before starting.
1640 // Note: Due to JVM_StopThread we can have pending exceptions already!
1641 if (!this->has_pending_exception() &&
1642 !java_lang_Thread::is_stillborn(this->threadObj())) {
1643 {
1644 ResourceMark rm(this);
1645 this->set_native_thread_name(this->get_thread_name());
1646 }
1647 HandleMark hm(this);
1648 this->entry_point()(this, this);
1649 }
1650
1651 DTRACE_THREAD_PROBE(stop, this);
1652
1653 this->exit(false);
1654 delete this;
1655 }
1656
1657
1658 static void ensure_join(JavaThread* thread) {
1659 // We do not need to grap the Threads_lock, since we are operating on ourself.
1660 Handle threadObj(thread, thread->threadObj());
1661 assert(threadObj.not_null(), "java thread object must exist");
1662 ObjectLocker lock(threadObj, thread);
1663 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1664 thread->clear_pending_exception();
1665 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1666 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1667 // Clear the native thread instance - this makes isAlive return false and allows the join()
1668 // to complete once we've done the notify_all below
1669 java_lang_Thread::set_thread(threadObj(), NULL);
1670 lock.notify_all(thread);
1671 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1672 thread->clear_pending_exception();
1673 }
1674
1675
1676 // For any new cleanup additions, please check to see if they need to be applied to
1677 // cleanup_failed_attach_current_thread as well.
1678 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1679 assert(this == JavaThread::current(), "thread consistency check");
1680
1681 HandleMark hm(this);
1682 Handle uncaught_exception(this, this->pending_exception());
1683 this->clear_pending_exception();
1684 Handle threadObj(this, this->threadObj());
1685 assert(threadObj.not_null(), "Java thread object should be created");
1686
1687 if (get_thread_profiler() != NULL) {
1688 get_thread_profiler()->disengage();
1689 ResourceMark rm;
1690 get_thread_profiler()->print(get_thread_name());
1691 }
1692
1693
1694 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1695 {
1696 EXCEPTION_MARK;
1697
1698 CLEAR_PENDING_EXCEPTION;
1699 }
1700 if (!destroy_vm) {
1701 if (uncaught_exception.not_null()) {
1702 EXCEPTION_MARK;
1703 // Call method Thread.dispatchUncaughtException().
1704 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1705 JavaValue result(T_VOID);
1706 JavaCalls::call_virtual(&result,
1707 threadObj, thread_klass,
1708 vmSymbols::dispatchUncaughtException_name(),
1709 vmSymbols::throwable_void_signature(),
1710 uncaught_exception,
1711 THREAD);
1712 if (HAS_PENDING_EXCEPTION) {
1713 ResourceMark rm(this);
1714 jio_fprintf(defaultStream::error_stream(),
1715 "\nException: %s thrown from the UncaughtExceptionHandler"
1716 " in thread \"%s\"\n",
1717 pending_exception()->klass()->external_name(),
1718 get_thread_name());
1719 CLEAR_PENDING_EXCEPTION;
1720 }
1721 }
1722
1723 // Called before the java thread exit since we want to read info
1724 // from java_lang_Thread object
1725 EventThreadEnd event;
1726 if (event.should_commit()) {
1727 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1728 event.commit();
1729 }
1730
1731 // Call after last event on thread
1732 EVENT_THREAD_EXIT(this);
1733
1734 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1735 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1736 // is deprecated anyhow.
1737 if (!is_Compiler_thread()) {
1738 int count = 3;
1739 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1740 EXCEPTION_MARK;
1741 JavaValue result(T_VOID);
1742 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1743 JavaCalls::call_virtual(&result,
1744 threadObj, thread_klass,
1745 vmSymbols::exit_method_name(),
1746 vmSymbols::void_method_signature(),
1747 THREAD);
1748 CLEAR_PENDING_EXCEPTION;
1749 }
1750 }
1751 // notify JVMTI
1752 if (JvmtiExport::should_post_thread_life()) {
1753 JvmtiExport::post_thread_end(this);
1754 }
1755
1756 // We have notified the agents that we are exiting, before we go on,
1757 // we must check for a pending external suspend request and honor it
1758 // in order to not surprise the thread that made the suspend request.
1759 while (true) {
1760 {
1761 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1762 if (!is_external_suspend()) {
1763 set_terminated(_thread_exiting);
1764 ThreadService::current_thread_exiting(this);
1765 break;
1766 }
1767 // Implied else:
1768 // Things get a little tricky here. We have a pending external
1769 // suspend request, but we are holding the SR_lock so we
1770 // can't just self-suspend. So we temporarily drop the lock
1771 // and then self-suspend.
1772 }
1773
1774 ThreadBlockInVM tbivm(this);
1775 java_suspend_self();
1776
1777 // We're done with this suspend request, but we have to loop around
1778 // and check again. Eventually we will get SR_lock without a pending
1779 // external suspend request and will be able to mark ourselves as
1780 // exiting.
1781 }
1782 // no more external suspends are allowed at this point
1783 } else {
1784 // before_exit() has already posted JVMTI THREAD_END events
1785 }
1786
1787 // Notify waiters on thread object. This has to be done after exit() is called
1788 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1789 // group should have the destroyed bit set before waiters are notified).
1790 ensure_join(this);
1791 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1792
1793 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1794 // held by this thread must be released. A detach operation must only
1795 // get here if there are no Java frames on the stack. Therefore, any
1796 // owned monitors at this point MUST be JNI-acquired monitors which are
1797 // pre-inflated and in the monitor cache.
1798 //
1799 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1800 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1801 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1802 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1803 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1804 }
1805
1806 // These things needs to be done while we are still a Java Thread. Make sure that thread
1807 // is in a consistent state, in case GC happens
1808 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1809
1810 if (active_handles() != NULL) {
1811 JNIHandleBlock* block = active_handles();
1812 set_active_handles(NULL);
1813 JNIHandleBlock::release_block(block);
1814 }
1815
1816 if (free_handle_block() != NULL) {
1817 JNIHandleBlock* block = free_handle_block();
1818 set_free_handle_block(NULL);
1819 JNIHandleBlock::release_block(block);
1820 }
1821
1822 // These have to be removed while this is still a valid thread.
1823 remove_stack_guard_pages();
1824
1825 if (UseTLAB) {
1826 tlab().make_parsable(true); // retire TLAB
1827 }
1828
1829 if (JvmtiEnv::environments_might_exist()) {
1830 JvmtiExport::cleanup_thread(this);
1831 }
1832
1833 // We must flush any deferred card marks before removing a thread from
1834 // the list of active threads.
1835 Universe::heap()->flush_deferred_store_barrier(this);
1836 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1837
1838 #if INCLUDE_ALL_GCS
1839 // We must flush the G1-related buffers before removing a thread
1840 // from the list of active threads. We must do this after any deferred
1841 // card marks have been flushed (above) so that any entries that are
1842 // added to the thread's dirty card queue as a result are not lost.
1843 if (UseG1GC) {
1844 flush_barrier_queues();
1845 }
1846 #endif // INCLUDE_ALL_GCS
1847
1848 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1849 Threads::remove(this);
1850 }
1851
1852 #if INCLUDE_ALL_GCS
1853 // Flush G1-related queues.
1854 void JavaThread::flush_barrier_queues() {
1855 satb_mark_queue().flush();
1856 dirty_card_queue().flush();
1857 }
1858
1859 void JavaThread::initialize_queues() {
1860 assert(!SafepointSynchronize::is_at_safepoint(),
1861 "we should not be at a safepoint");
1862
1863 ObjPtrQueue& satb_queue = satb_mark_queue();
1864 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1865 // The SATB queue should have been constructed with its active
1866 // field set to false.
1867 assert(!satb_queue.is_active(), "SATB queue should not be active");
1868 assert(satb_queue.is_empty(), "SATB queue should be empty");
1869 // If we are creating the thread during a marking cycle, we should
1870 // set the active field of the SATB queue to true.
1871 if (satb_queue_set.is_active()) {
1872 satb_queue.set_active(true);
1873 }
1874
1875 DirtyCardQueue& dirty_queue = dirty_card_queue();
1876 // The dirty card queue should have been constructed with its
1877 // active field set to true.
1878 assert(dirty_queue.is_active(), "dirty card queue should be active");
1879 }
1880 #endif // INCLUDE_ALL_GCS
1881
1882 void JavaThread::cleanup_failed_attach_current_thread() {
1883 if (get_thread_profiler() != NULL) {
1884 get_thread_profiler()->disengage();
1885 ResourceMark rm;
1886 get_thread_profiler()->print(get_thread_name());
1887 }
1888
1889 if (active_handles() != NULL) {
1890 JNIHandleBlock* block = active_handles();
1891 set_active_handles(NULL);
1892 JNIHandleBlock::release_block(block);
1893 }
1894
1895 if (free_handle_block() != NULL) {
1896 JNIHandleBlock* block = free_handle_block();
1897 set_free_handle_block(NULL);
1898 JNIHandleBlock::release_block(block);
1899 }
1900
1901 // These have to be removed while this is still a valid thread.
1902 remove_stack_guard_pages();
1903
1904 if (UseTLAB) {
1905 tlab().make_parsable(true); // retire TLAB, if any
1906 }
1907
1908 #if INCLUDE_ALL_GCS
1909 if (UseG1GC) {
1910 flush_barrier_queues();
1911 }
1912 #endif // INCLUDE_ALL_GCS
1913
1914 Threads::remove(this);
1915 delete this;
1916 }
1917
1918
1919
1920
1921 JavaThread* JavaThread::active() {
1922 Thread* thread = ThreadLocalStorage::thread();
1923 assert(thread != NULL, "just checking");
1924 if (thread->is_Java_thread()) {
1925 return (JavaThread*) thread;
1926 } else {
1927 assert(thread->is_VM_thread(), "this must be a vm thread");
1928 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1929 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1930 assert(ret->is_Java_thread(), "must be a Java thread");
1931 return ret;
1932 }
1933 }
1934
1935 bool JavaThread::is_lock_owned(address adr) const {
1936 if (Thread::is_lock_owned(adr)) return true;
1937
1938 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1939 if (chunk->contains(adr)) return true;
1940 }
1941
1942 return false;
1943 }
1944
1945
1946 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1947 chunk->set_next(monitor_chunks());
1948 set_monitor_chunks(chunk);
1949 }
1950
1951 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1952 guarantee(monitor_chunks() != NULL, "must be non empty");
1953 if (monitor_chunks() == chunk) {
1954 set_monitor_chunks(chunk->next());
1955 } else {
1956 MonitorChunk* prev = monitor_chunks();
1957 while (prev->next() != chunk) prev = prev->next();
1958 prev->set_next(chunk->next());
1959 }
1960 }
1961
1962 // JVM support.
1963
1964 // Note: this function shouldn't block if it's called in
1965 // _thread_in_native_trans state (such as from
1966 // check_special_condition_for_native_trans()).
1967 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1968
1969 if (has_last_Java_frame() && has_async_condition()) {
1970 // If we are at a polling page safepoint (not a poll return)
1971 // then we must defer async exception because live registers
1972 // will be clobbered by the exception path. Poll return is
1973 // ok because the call we a returning from already collides
1974 // with exception handling registers and so there is no issue.
1975 // (The exception handling path kills call result registers but
1976 // this is ok since the exception kills the result anyway).
1977
1978 if (is_at_poll_safepoint()) {
1979 // if the code we are returning to has deoptimized we must defer
1980 // the exception otherwise live registers get clobbered on the
1981 // exception path before deoptimization is able to retrieve them.
1982 //
1983 RegisterMap map(this, false);
1984 frame caller_fr = last_frame().sender(&map);
1985 assert(caller_fr.is_compiled_frame(), "what?");
1986 if (caller_fr.is_deoptimized_frame()) {
1987 if (TraceExceptions) {
1988 ResourceMark rm;
1989 tty->print_cr("deferred async exception at compiled safepoint");
1990 }
1991 return;
1992 }
1993 }
1994 }
1995
1996 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1997 if (condition == _no_async_condition) {
1998 // Conditions have changed since has_special_runtime_exit_condition()
1999 // was called:
2000 // - if we were here only because of an external suspend request,
2001 // then that was taken care of above (or cancelled) so we are done
2002 // - if we were here because of another async request, then it has
2003 // been cleared between the has_special_runtime_exit_condition()
2004 // and now so again we are done
2005 return;
2006 }
2007
2008 // Check for pending async. exception
2009 if (_pending_async_exception != NULL) {
2010 // Only overwrite an already pending exception, if it is not a threadDeath.
2011 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2012
2013 // We cannot call Exceptions::_throw(...) here because we cannot block
2014 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2015
2016 if (TraceExceptions) {
2017 ResourceMark rm;
2018 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2019 if (has_last_Java_frame()) {
2020 frame f = last_frame();
2021 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2022 }
2023 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2024 }
2025 _pending_async_exception = NULL;
2026 clear_has_async_exception();
2027 }
2028 }
2029
2030 if (check_unsafe_error &&
2031 condition == _async_unsafe_access_error && !has_pending_exception()) {
2032 condition = _no_async_condition; // done
2033 switch (thread_state()) {
2034 case _thread_in_vm: {
2035 JavaThread* THREAD = this;
2036 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2037 }
2038 case _thread_in_native: {
2039 ThreadInVMfromNative tiv(this);
2040 JavaThread* THREAD = this;
2041 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2042 }
2043 case _thread_in_Java: {
2044 ThreadInVMfromJava tiv(this);
2045 JavaThread* THREAD = this;
2046 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2047 }
2048 default:
2049 ShouldNotReachHere();
2050 }
2051 }
2052
2053 assert(condition == _no_async_condition || has_pending_exception() ||
2054 (!check_unsafe_error && condition == _async_unsafe_access_error),
2055 "must have handled the async condition, if no exception");
2056 }
2057
2058 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2059 //
2060 // Check for pending external suspend. Internal suspend requests do
2061 // not use handle_special_runtime_exit_condition().
2062 // If JNIEnv proxies are allowed, don't self-suspend if the target
2063 // thread is not the current thread. In older versions of jdbx, jdbx
2064 // threads could call into the VM with another thread's JNIEnv so we
2065 // can be here operating on behalf of a suspended thread (4432884).
2066 bool do_self_suspend = is_external_suspend_with_lock();
2067 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2068 //
2069 // Because thread is external suspended the safepoint code will count
2070 // thread as at a safepoint. This can be odd because we can be here
2071 // as _thread_in_Java which would normally transition to _thread_blocked
2072 // at a safepoint. We would like to mark the thread as _thread_blocked
2073 // before calling java_suspend_self like all other callers of it but
2074 // we must then observe proper safepoint protocol. (We can't leave
2075 // _thread_blocked with a safepoint in progress). However we can be
2076 // here as _thread_in_native_trans so we can't use a normal transition
2077 // constructor/destructor pair because they assert on that type of
2078 // transition. We could do something like:
2079 //
2080 // JavaThreadState state = thread_state();
2081 // set_thread_state(_thread_in_vm);
2082 // {
2083 // ThreadBlockInVM tbivm(this);
2084 // java_suspend_self()
2085 // }
2086 // set_thread_state(_thread_in_vm_trans);
2087 // if (safepoint) block;
2088 // set_thread_state(state);
2089 //
2090 // but that is pretty messy. Instead we just go with the way the
2091 // code has worked before and note that this is the only path to
2092 // java_suspend_self that doesn't put the thread in _thread_blocked
2093 // mode.
2094
2095 frame_anchor()->make_walkable(this);
2096 java_suspend_self();
2097
2098 // We might be here for reasons in addition to the self-suspend request
2099 // so check for other async requests.
2100 }
2101
2102 if (check_asyncs) {
2103 check_and_handle_async_exceptions();
2104 }
2105 }
2106
2107 void JavaThread::send_thread_stop(oop java_throwable) {
2108 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2109 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2110 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2111
2112 // Do not throw asynchronous exceptions against the compiler thread
2113 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2114 if (is_Compiler_thread()) return;
2115
2116 {
2117 // Actually throw the Throwable against the target Thread - however
2118 // only if there is no thread death exception installed already.
2119 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2120 // If the topmost frame is a runtime stub, then we are calling into
2121 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2122 // must deoptimize the caller before continuing, as the compiled exception handler table
2123 // may not be valid
2124 if (has_last_Java_frame()) {
2125 frame f = last_frame();
2126 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2127 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2128 RegisterMap reg_map(this, UseBiasedLocking);
2129 frame compiled_frame = f.sender(®_map);
2130 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2131 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2132 }
2133 }
2134 }
2135
2136 // Set async. pending exception in thread.
2137 set_pending_async_exception(java_throwable);
2138
2139 if (TraceExceptions) {
2140 ResourceMark rm;
2141 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2142 }
2143 // for AbortVMOnException flag
2144 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2145 }
2146 }
2147
2148
2149 // Interrupt thread so it will wake up from a potential wait()
2150 Thread::interrupt(this);
2151 }
2152
2153 // External suspension mechanism.
2154 //
2155 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2156 // to any VM_locks and it is at a transition
2157 // Self-suspension will happen on the transition out of the vm.
2158 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2159 //
2160 // Guarantees on return:
2161 // + Target thread will not execute any new bytecode (that's why we need to
2162 // force a safepoint)
2163 // + Target thread will not enter any new monitors
2164 //
2165 void JavaThread::java_suspend() {
2166 { MutexLocker mu(Threads_lock);
2167 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2168 return;
2169 }
2170 }
2171
2172 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2173 if (!is_external_suspend()) {
2174 // a racing resume has cancelled us; bail out now
2175 return;
2176 }
2177
2178 // suspend is done
2179 uint32_t debug_bits = 0;
2180 // Warning: is_ext_suspend_completed() may temporarily drop the
2181 // SR_lock to allow the thread to reach a stable thread state if
2182 // it is currently in a transient thread state.
2183 if (is_ext_suspend_completed(false /* !called_by_wait */,
2184 SuspendRetryDelay, &debug_bits)) {
2185 return;
2186 }
2187 }
2188
2189 VM_ForceSafepoint vm_suspend;
2190 VMThread::execute(&vm_suspend);
2191 }
2192
2193 // Part II of external suspension.
2194 // A JavaThread self suspends when it detects a pending external suspend
2195 // request. This is usually on transitions. It is also done in places
2196 // where continuing to the next transition would surprise the caller,
2197 // e.g., monitor entry.
2198 //
2199 // Returns the number of times that the thread self-suspended.
2200 //
2201 // Note: DO NOT call java_suspend_self() when you just want to block current
2202 // thread. java_suspend_self() is the second stage of cooperative
2203 // suspension for external suspend requests and should only be used
2204 // to complete an external suspend request.
2205 //
2206 int JavaThread::java_suspend_self() {
2207 int ret = 0;
2208
2209 // we are in the process of exiting so don't suspend
2210 if (is_exiting()) {
2211 clear_external_suspend();
2212 return ret;
2213 }
2214
2215 assert(_anchor.walkable() ||
2216 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2217 "must have walkable stack");
2218
2219 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2220
2221 assert(!this->is_ext_suspended(),
2222 "a thread trying to self-suspend should not already be suspended");
2223
2224 if (this->is_suspend_equivalent()) {
2225 // If we are self-suspending as a result of the lifting of a
2226 // suspend equivalent condition, then the suspend_equivalent
2227 // flag is not cleared until we set the ext_suspended flag so
2228 // that wait_for_ext_suspend_completion() returns consistent
2229 // results.
2230 this->clear_suspend_equivalent();
2231 }
2232
2233 // A racing resume may have cancelled us before we grabbed SR_lock
2234 // above. Or another external suspend request could be waiting for us
2235 // by the time we return from SR_lock()->wait(). The thread
2236 // that requested the suspension may already be trying to walk our
2237 // stack and if we return now, we can change the stack out from under
2238 // it. This would be a "bad thing (TM)" and cause the stack walker
2239 // to crash. We stay self-suspended until there are no more pending
2240 // external suspend requests.
2241 while (is_external_suspend()) {
2242 ret++;
2243 this->set_ext_suspended();
2244
2245 // _ext_suspended flag is cleared by java_resume()
2246 while (is_ext_suspended()) {
2247 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2248 }
2249 }
2250
2251 return ret;
2252 }
2253
2254 #ifdef ASSERT
2255 // verify the JavaThread has not yet been published in the Threads::list, and
2256 // hence doesn't need protection from concurrent access at this stage
2257 void JavaThread::verify_not_published() {
2258 if (!Threads_lock->owned_by_self()) {
2259 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2260 assert(!Threads::includes(this),
2261 "java thread shouldn't have been published yet!");
2262 } else {
2263 assert(!Threads::includes(this),
2264 "java thread shouldn't have been published yet!");
2265 }
2266 }
2267 #endif
2268
2269 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2270 // progress or when _suspend_flags is non-zero.
2271 // Current thread needs to self-suspend if there is a suspend request and/or
2272 // block if a safepoint is in progress.
2273 // Async exception ISN'T checked.
2274 // Note only the ThreadInVMfromNative transition can call this function
2275 // directly and when thread state is _thread_in_native_trans
2276 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2277 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2278
2279 JavaThread *curJT = JavaThread::current();
2280 bool do_self_suspend = thread->is_external_suspend();
2281
2282 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2283
2284 // If JNIEnv proxies are allowed, don't self-suspend if the target
2285 // thread is not the current thread. In older versions of jdbx, jdbx
2286 // threads could call into the VM with another thread's JNIEnv so we
2287 // can be here operating on behalf of a suspended thread (4432884).
2288 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2289 JavaThreadState state = thread->thread_state();
2290
2291 // We mark this thread_blocked state as a suspend-equivalent so
2292 // that a caller to is_ext_suspend_completed() won't be confused.
2293 // The suspend-equivalent state is cleared by java_suspend_self().
2294 thread->set_suspend_equivalent();
2295
2296 // If the safepoint code sees the _thread_in_native_trans state, it will
2297 // wait until the thread changes to other thread state. There is no
2298 // guarantee on how soon we can obtain the SR_lock and complete the
2299 // self-suspend request. It would be a bad idea to let safepoint wait for
2300 // too long. Temporarily change the state to _thread_blocked to
2301 // let the VM thread know that this thread is ready for GC. The problem
2302 // of changing thread state is that safepoint could happen just after
2303 // java_suspend_self() returns after being resumed, and VM thread will
2304 // see the _thread_blocked state. We must check for safepoint
2305 // after restoring the state and make sure we won't leave while a safepoint
2306 // is in progress.
2307 thread->set_thread_state(_thread_blocked);
2308 thread->java_suspend_self();
2309 thread->set_thread_state(state);
2310 // Make sure new state is seen by VM thread
2311 if (os::is_MP()) {
2312 if (UseMembar) {
2313 // Force a fence between the write above and read below
2314 OrderAccess::fence();
2315 } else {
2316 // Must use this rather than serialization page in particular on Windows
2317 InterfaceSupport::serialize_memory(thread);
2318 }
2319 }
2320 }
2321
2322 if (SafepointSynchronize::do_call_back()) {
2323 // If we are safepointing, then block the caller which may not be
2324 // the same as the target thread (see above).
2325 SafepointSynchronize::block(curJT);
2326 }
2327
2328 if (thread->is_deopt_suspend()) {
2329 thread->clear_deopt_suspend();
2330 RegisterMap map(thread, false);
2331 frame f = thread->last_frame();
2332 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2333 f = f.sender(&map);
2334 }
2335 if (f.id() == thread->must_deopt_id()) {
2336 thread->clear_must_deopt_id();
2337 f.deoptimize(thread);
2338 } else {
2339 fatal("missed deoptimization!");
2340 }
2341 }
2342 }
2343
2344 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2345 // progress or when _suspend_flags is non-zero.
2346 // Current thread needs to self-suspend if there is a suspend request and/or
2347 // block if a safepoint is in progress.
2348 // Also check for pending async exception (not including unsafe access error).
2349 // Note only the native==>VM/Java barriers can call this function and when
2350 // thread state is _thread_in_native_trans.
2351 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2352 check_safepoint_and_suspend_for_native_trans(thread);
2353
2354 if (thread->has_async_exception()) {
2355 // We are in _thread_in_native_trans state, don't handle unsafe
2356 // access error since that may block.
2357 thread->check_and_handle_async_exceptions(false);
2358 }
2359 }
2360
2361 // This is a variant of the normal
2362 // check_special_condition_for_native_trans with slightly different
2363 // semantics for use by critical native wrappers. It does all the
2364 // normal checks but also performs the transition back into
2365 // thread_in_Java state. This is required so that critical natives
2366 // can potentially block and perform a GC if they are the last thread
2367 // exiting the GC_locker.
2368 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2369 check_special_condition_for_native_trans(thread);
2370
2371 // Finish the transition
2372 thread->set_thread_state(_thread_in_Java);
2373
2374 if (thread->do_critical_native_unlock()) {
2375 ThreadInVMfromJavaNoAsyncException tiv(thread);
2376 GC_locker::unlock_critical(thread);
2377 thread->clear_critical_native_unlock();
2378 }
2379 }
2380
2381 // We need to guarantee the Threads_lock here, since resumes are not
2382 // allowed during safepoint synchronization
2383 // Can only resume from an external suspension
2384 void JavaThread::java_resume() {
2385 assert_locked_or_safepoint(Threads_lock);
2386
2387 // Sanity check: thread is gone, has started exiting or the thread
2388 // was not externally suspended.
2389 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2390 return;
2391 }
2392
2393 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2394
2395 clear_external_suspend();
2396
2397 if (is_ext_suspended()) {
2398 clear_ext_suspended();
2399 SR_lock()->notify_all();
2400 }
2401 }
2402
2403 void JavaThread::create_stack_guard_pages() {
2404 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2405 address low_addr = stack_base() - stack_size();
2406 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2407
2408 int allocate = os::allocate_stack_guard_pages();
2409 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2410
2411 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2412 warning("Attempt to allocate stack guard pages failed.");
2413 return;
2414 }
2415
2416 if (os::guard_memory((char *) low_addr, len)) {
2417 _stack_guard_state = stack_guard_enabled;
2418 } else {
2419 warning("Attempt to protect stack guard pages failed.");
2420 if (os::uncommit_memory((char *) low_addr, len)) {
2421 warning("Attempt to deallocate stack guard pages failed.");
2422 }
2423 }
2424 }
2425
2426 void JavaThread::remove_stack_guard_pages() {
2427 assert(Thread::current() == this, "from different thread");
2428 if (_stack_guard_state == stack_guard_unused) return;
2429 address low_addr = stack_base() - stack_size();
2430 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2431
2432 if (os::allocate_stack_guard_pages()) {
2433 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2434 _stack_guard_state = stack_guard_unused;
2435 } else {
2436 warning("Attempt to deallocate stack guard pages failed.");
2437 }
2438 } else {
2439 if (_stack_guard_state == stack_guard_unused) return;
2440 if (os::unguard_memory((char *) low_addr, len)) {
2441 _stack_guard_state = stack_guard_unused;
2442 } else {
2443 warning("Attempt to unprotect stack guard pages failed.");
2444 }
2445 }
2446 }
2447
2448 void JavaThread::enable_stack_yellow_zone() {
2449 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2450 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2451
2452 // The base notation is from the stacks point of view, growing downward.
2453 // We need to adjust it to work correctly with guard_memory()
2454 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2455
2456 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2457 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2458
2459 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2460 _stack_guard_state = stack_guard_enabled;
2461 } else {
2462 warning("Attempt to guard stack yellow zone failed.");
2463 }
2464 enable_register_stack_guard();
2465 }
2466
2467 void JavaThread::disable_stack_yellow_zone() {
2468 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2469 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2470
2471 // Simply return if called for a thread that does not use guard pages.
2472 if (_stack_guard_state == stack_guard_unused) return;
2473
2474 // The base notation is from the stacks point of view, growing downward.
2475 // We need to adjust it to work correctly with guard_memory()
2476 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2477
2478 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2479 _stack_guard_state = stack_guard_yellow_disabled;
2480 } else {
2481 warning("Attempt to unguard stack yellow zone failed.");
2482 }
2483 disable_register_stack_guard();
2484 }
2485
2486 void JavaThread::enable_stack_red_zone() {
2487 // The base notation is from the stacks point of view, growing downward.
2488 // We need to adjust it to work correctly with guard_memory()
2489 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2490 address base = stack_red_zone_base() - stack_red_zone_size();
2491
2492 guarantee(base < stack_base(), "Error calculating stack red zone");
2493 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2494
2495 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2496 warning("Attempt to guard stack red zone failed.");
2497 }
2498 }
2499
2500 void JavaThread::disable_stack_red_zone() {
2501 // The base notation is from the stacks point of view, growing downward.
2502 // We need to adjust it to work correctly with guard_memory()
2503 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2504 address base = stack_red_zone_base() - stack_red_zone_size();
2505 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2506 warning("Attempt to unguard stack red zone failed.");
2507 }
2508 }
2509
2510 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2511 // ignore is there is no stack
2512 if (!has_last_Java_frame()) return;
2513 // traverse the stack frames. Starts from top frame.
2514 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2515 frame* fr = fst.current();
2516 f(fr, fst.register_map());
2517 }
2518 }
2519
2520
2521 #ifndef PRODUCT
2522 // Deoptimization
2523 // Function for testing deoptimization
2524 void JavaThread::deoptimize() {
2525 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2526 StackFrameStream fst(this, UseBiasedLocking);
2527 bool deopt = false; // Dump stack only if a deopt actually happens.
2528 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2529 // Iterate over all frames in the thread and deoptimize
2530 for (; !fst.is_done(); fst.next()) {
2531 if (fst.current()->can_be_deoptimized()) {
2532
2533 if (only_at) {
2534 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2535 // consists of comma or carriage return separated numbers so
2536 // search for the current bci in that string.
2537 address pc = fst.current()->pc();
2538 nmethod* nm = (nmethod*) fst.current()->cb();
2539 ScopeDesc* sd = nm->scope_desc_at(pc);
2540 char buffer[8];
2541 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2542 size_t len = strlen(buffer);
2543 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2544 while (found != NULL) {
2545 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2546 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2547 // Check that the bci found is bracketed by terminators.
2548 break;
2549 }
2550 found = strstr(found + 1, buffer);
2551 }
2552 if (!found) {
2553 continue;
2554 }
2555 }
2556
2557 if (DebugDeoptimization && !deopt) {
2558 deopt = true; // One-time only print before deopt
2559 tty->print_cr("[BEFORE Deoptimization]");
2560 trace_frames();
2561 trace_stack();
2562 }
2563 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2564 }
2565 }
2566
2567 if (DebugDeoptimization && deopt) {
2568 tty->print_cr("[AFTER Deoptimization]");
2569 trace_frames();
2570 }
2571 }
2572
2573
2574 // Make zombies
2575 void JavaThread::make_zombies() {
2576 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2577 if (fst.current()->can_be_deoptimized()) {
2578 // it is a Java nmethod
2579 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2580 nm->make_not_entrant();
2581 }
2582 }
2583 }
2584 #endif // PRODUCT
2585
2586
2587 void JavaThread::deoptimized_wrt_marked_nmethods() {
2588 if (!has_last_Java_frame()) return;
2589 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2590 StackFrameStream fst(this, UseBiasedLocking);
2591 for (; !fst.is_done(); fst.next()) {
2592 if (fst.current()->should_be_deoptimized()) {
2593 if (LogCompilation && xtty != NULL) {
2594 nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2595 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2596 this->name(), nm != NULL ? nm->compile_id() : -1);
2597 }
2598
2599 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2600 }
2601 }
2602 }
2603
2604
2605 // If the caller is a NamedThread, then remember, in the current scope,
2606 // the given JavaThread in its _processed_thread field.
2607 class RememberProcessedThread: public StackObj {
2608 NamedThread* _cur_thr;
2609 public:
2610 RememberProcessedThread(JavaThread* jthr) {
2611 Thread* thread = Thread::current();
2612 if (thread->is_Named_thread()) {
2613 _cur_thr = (NamedThread *)thread;
2614 _cur_thr->set_processed_thread(jthr);
2615 } else {
2616 _cur_thr = NULL;
2617 }
2618 }
2619
2620 ~RememberProcessedThread() {
2621 if (_cur_thr) {
2622 _cur_thr->set_processed_thread(NULL);
2623 }
2624 }
2625 };
2626
2627 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2628 // Verify that the deferred card marks have been flushed.
2629 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2630
2631 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2632 // since there may be more than one thread using each ThreadProfiler.
2633
2634 // Traverse the GCHandles
2635 Thread::oops_do(f, cld_f, cf);
2636
2637 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2638 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2639
2640 if (has_last_Java_frame()) {
2641 // Record JavaThread to GC thread
2642 RememberProcessedThread rpt(this);
2643
2644 // Traverse the privileged stack
2645 if (_privileged_stack_top != NULL) {
2646 _privileged_stack_top->oops_do(f);
2647 }
2648
2649 // traverse the registered growable array
2650 if (_array_for_gc != NULL) {
2651 for (int index = 0; index < _array_for_gc->length(); index++) {
2652 f->do_oop(_array_for_gc->adr_at(index));
2653 }
2654 }
2655
2656 // Traverse the monitor chunks
2657 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2658 chunk->oops_do(f);
2659 }
2660
2661 // Traverse the execution stack
2662 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2663 fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2664 }
2665 }
2666
2667 // callee_target is never live across a gc point so NULL it here should
2668 // it still contain a methdOop.
2669
2670 set_callee_target(NULL);
2671
2672 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2673 // If we have deferred set_locals there might be oops waiting to be
2674 // written
2675 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2676 if (list != NULL) {
2677 for (int i = 0; i < list->length(); i++) {
2678 list->at(i)->oops_do(f);
2679 }
2680 }
2681
2682 // Traverse instance variables at the end since the GC may be moving things
2683 // around using this function
2684 f->do_oop((oop*) &_threadObj);
2685 f->do_oop((oop*) &_vm_result);
2686 f->do_oop((oop*) &_exception_oop);
2687 f->do_oop((oop*) &_pending_async_exception);
2688
2689 if (jvmti_thread_state() != NULL) {
2690 jvmti_thread_state()->oops_do(f);
2691 }
2692 }
2693
2694 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2695 Thread::nmethods_do(cf); // (super method is a no-op)
2696
2697 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2698 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2699
2700 if (has_last_Java_frame()) {
2701 // Traverse the execution stack
2702 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2703 fst.current()->nmethods_do(cf);
2704 }
2705 }
2706 }
2707
2708 void JavaThread::metadata_do(void f(Metadata*)) {
2709 Thread::metadata_do(f);
2710 if (has_last_Java_frame()) {
2711 // Traverse the execution stack to call f() on the methods in the stack
2712 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2713 fst.current()->metadata_do(f);
2714 }
2715 } else if (is_Compiler_thread()) {
2716 // need to walk ciMetadata in current compile tasks to keep alive.
2717 CompilerThread* ct = (CompilerThread*)this;
2718 if (ct->env() != NULL) {
2719 ct->env()->metadata_do(f);
2720 }
2721 }
2722 }
2723
2724 // Printing
2725 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2726 switch (_thread_state) {
2727 case _thread_uninitialized: return "_thread_uninitialized";
2728 case _thread_new: return "_thread_new";
2729 case _thread_new_trans: return "_thread_new_trans";
2730 case _thread_in_native: return "_thread_in_native";
2731 case _thread_in_native_trans: return "_thread_in_native_trans";
2732 case _thread_in_vm: return "_thread_in_vm";
2733 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2734 case _thread_in_Java: return "_thread_in_Java";
2735 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2736 case _thread_blocked: return "_thread_blocked";
2737 case _thread_blocked_trans: return "_thread_blocked_trans";
2738 default: return "unknown thread state";
2739 }
2740 }
2741
2742 #ifndef PRODUCT
2743 void JavaThread::print_thread_state_on(outputStream *st) const {
2744 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2745 };
2746 void JavaThread::print_thread_state() const {
2747 print_thread_state_on(tty);
2748 }
2749 #endif // PRODUCT
2750
2751 // Called by Threads::print() for VM_PrintThreads operation
2752 void JavaThread::print_on(outputStream *st) const {
2753 st->print("\"%s\" ", get_thread_name());
2754 oop thread_oop = threadObj();
2755 if (thread_oop != NULL) {
2756 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2757 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2758 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2759 }
2760 Thread::print_on(st);
2761 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2762 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2763 if (thread_oop != NULL) {
2764 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2765 }
2766 #ifndef PRODUCT
2767 print_thread_state_on(st);
2768 _safepoint_state->print_on(st);
2769 #endif // PRODUCT
2770 }
2771
2772 // Called by fatal error handler. The difference between this and
2773 // JavaThread::print() is that we can't grab lock or allocate memory.
2774 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2775 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2776 oop thread_obj = threadObj();
2777 if (thread_obj != NULL) {
2778 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2779 }
2780 st->print(" [");
2781 st->print("%s", _get_thread_state_name(_thread_state));
2782 if (osthread()) {
2783 st->print(", id=%d", osthread()->thread_id());
2784 }
2785 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2786 _stack_base - _stack_size, _stack_base);
2787 st->print("]");
2788 return;
2789 }
2790
2791 // Verification
2792
2793 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2794
2795 void JavaThread::verify() {
2796 // Verify oops in the thread.
2797 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2798
2799 // Verify the stack frames.
2800 frames_do(frame_verify);
2801 }
2802
2803 // CR 6300358 (sub-CR 2137150)
2804 // Most callers of this method assume that it can't return NULL but a
2805 // thread may not have a name whilst it is in the process of attaching to
2806 // the VM - see CR 6412693, and there are places where a JavaThread can be
2807 // seen prior to having it's threadObj set (eg JNI attaching threads and
2808 // if vm exit occurs during initialization). These cases can all be accounted
2809 // for such that this method never returns NULL.
2810 const char* JavaThread::get_thread_name() const {
2811 #ifdef ASSERT
2812 // early safepoints can hit while current thread does not yet have TLS
2813 if (!SafepointSynchronize::is_at_safepoint()) {
2814 Thread *cur = Thread::current();
2815 if (!(cur->is_Java_thread() && cur == this)) {
2816 // Current JavaThreads are allowed to get their own name without
2817 // the Threads_lock.
2818 assert_locked_or_safepoint(Threads_lock);
2819 }
2820 }
2821 #endif // ASSERT
2822 return get_thread_name_string();
2823 }
2824
2825 // Returns a non-NULL representation of this thread's name, or a suitable
2826 // descriptive string if there is no set name
2827 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2828 const char* name_str;
2829 oop thread_obj = threadObj();
2830 if (thread_obj != NULL) {
2831 oop name = java_lang_Thread::name(thread_obj);
2832 if (name != NULL) {
2833 if (buf == NULL) {
2834 name_str = java_lang_String::as_utf8_string(name);
2835 } else {
2836 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2837 }
2838 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2839 name_str = "<no-name - thread is attaching>";
2840 } else {
2841 name_str = Thread::name();
2842 }
2843 } else {
2844 name_str = Thread::name();
2845 }
2846 assert(name_str != NULL, "unexpected NULL thread name");
2847 return name_str;
2848 }
2849
2850
2851 const char* JavaThread::get_threadgroup_name() const {
2852 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2853 oop thread_obj = threadObj();
2854 if (thread_obj != NULL) {
2855 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2856 if (thread_group != NULL) {
2857 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2858 // ThreadGroup.name can be null
2859 if (name != NULL) {
2860 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2861 return str;
2862 }
2863 }
2864 }
2865 return NULL;
2866 }
2867
2868 const char* JavaThread::get_parent_name() const {
2869 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2870 oop thread_obj = threadObj();
2871 if (thread_obj != NULL) {
2872 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2873 if (thread_group != NULL) {
2874 oop parent = java_lang_ThreadGroup::parent(thread_group);
2875 if (parent != NULL) {
2876 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2877 // ThreadGroup.name can be null
2878 if (name != NULL) {
2879 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2880 return str;
2881 }
2882 }
2883 }
2884 }
2885 return NULL;
2886 }
2887
2888 ThreadPriority JavaThread::java_priority() const {
2889 oop thr_oop = threadObj();
2890 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2891 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2892 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2893 return priority;
2894 }
2895
2896 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2897
2898 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2899 // Link Java Thread object <-> C++ Thread
2900
2901 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2902 // and put it into a new Handle. The Handle "thread_oop" can then
2903 // be used to pass the C++ thread object to other methods.
2904
2905 // Set the Java level thread object (jthread) field of the
2906 // new thread (a JavaThread *) to C++ thread object using the
2907 // "thread_oop" handle.
2908
2909 // Set the thread field (a JavaThread *) of the
2910 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2911
2912 Handle thread_oop(Thread::current(),
2913 JNIHandles::resolve_non_null(jni_thread));
2914 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2915 "must be initialized");
2916 set_threadObj(thread_oop());
2917 java_lang_Thread::set_thread(thread_oop(), this);
2918
2919 if (prio == NoPriority) {
2920 prio = java_lang_Thread::priority(thread_oop());
2921 assert(prio != NoPriority, "A valid priority should be present");
2922 }
2923
2924 // Push the Java priority down to the native thread; needs Threads_lock
2925 Thread::set_priority(this, prio);
2926
2927 prepare_ext();
2928
2929 // Add the new thread to the Threads list and set it in motion.
2930 // We must have threads lock in order to call Threads::add.
2931 // It is crucial that we do not block before the thread is
2932 // added to the Threads list for if a GC happens, then the java_thread oop
2933 // will not be visited by GC.
2934 Threads::add(this);
2935 }
2936
2937 oop JavaThread::current_park_blocker() {
2938 // Support for JSR-166 locks
2939 oop thread_oop = threadObj();
2940 if (thread_oop != NULL &&
2941 JDK_Version::current().supports_thread_park_blocker()) {
2942 return java_lang_Thread::park_blocker(thread_oop);
2943 }
2944 return NULL;
2945 }
2946
2947
2948 void JavaThread::print_stack_on(outputStream* st) {
2949 if (!has_last_Java_frame()) return;
2950 ResourceMark rm;
2951 HandleMark hm;
2952
2953 RegisterMap reg_map(this);
2954 vframe* start_vf = last_java_vframe(®_map);
2955 int count = 0;
2956 for (vframe* f = start_vf; f; f = f->sender()) {
2957 if (f->is_java_frame()) {
2958 javaVFrame* jvf = javaVFrame::cast(f);
2959 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2960
2961 // Print out lock information
2962 if (JavaMonitorsInStackTrace) {
2963 jvf->print_lock_info_on(st, count);
2964 }
2965 } else {
2966 // Ignore non-Java frames
2967 }
2968
2969 // Bail-out case for too deep stacks
2970 count++;
2971 if (MaxJavaStackTraceDepth == count) return;
2972 }
2973 }
2974
2975
2976 // JVMTI PopFrame support
2977 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2978 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2979 if (in_bytes(size_in_bytes) != 0) {
2980 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2981 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2982 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2983 }
2984 }
2985
2986 void* JavaThread::popframe_preserved_args() {
2987 return _popframe_preserved_args;
2988 }
2989
2990 ByteSize JavaThread::popframe_preserved_args_size() {
2991 return in_ByteSize(_popframe_preserved_args_size);
2992 }
2993
2994 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2995 int sz = in_bytes(popframe_preserved_args_size());
2996 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2997 return in_WordSize(sz / wordSize);
2998 }
2999
3000 void JavaThread::popframe_free_preserved_args() {
3001 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3002 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3003 _popframe_preserved_args = NULL;
3004 _popframe_preserved_args_size = 0;
3005 }
3006
3007 #ifndef PRODUCT
3008
3009 void JavaThread::trace_frames() {
3010 tty->print_cr("[Describe stack]");
3011 int frame_no = 1;
3012 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3013 tty->print(" %d. ", frame_no++);
3014 fst.current()->print_value_on(tty, this);
3015 tty->cr();
3016 }
3017 }
3018
3019 class PrintAndVerifyOopClosure: public OopClosure {
3020 protected:
3021 template <class T> inline void do_oop_work(T* p) {
3022 oop obj = oopDesc::load_decode_heap_oop(p);
3023 if (obj == NULL) return;
3024 tty->print(INTPTR_FORMAT ": ", p);
3025 if (obj->is_oop_or_null()) {
3026 if (obj->is_objArray()) {
3027 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3028 } else {
3029 obj->print();
3030 }
3031 } else {
3032 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3033 }
3034 tty->cr();
3035 }
3036 public:
3037 virtual void do_oop(oop* p) { do_oop_work(p); }
3038 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3039 };
3040
3041
3042 static void oops_print(frame* f, const RegisterMap *map) {
3043 PrintAndVerifyOopClosure print;
3044 f->print_value();
3045 f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3046 }
3047
3048 // Print our all the locations that contain oops and whether they are
3049 // valid or not. This useful when trying to find the oldest frame
3050 // where an oop has gone bad since the frame walk is from youngest to
3051 // oldest.
3052 void JavaThread::trace_oops() {
3053 tty->print_cr("[Trace oops]");
3054 frames_do(oops_print);
3055 }
3056
3057
3058 #ifdef ASSERT
3059 // Print or validate the layout of stack frames
3060 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3061 ResourceMark rm;
3062 PRESERVE_EXCEPTION_MARK;
3063 FrameValues values;
3064 int frame_no = 0;
3065 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3066 fst.current()->describe(values, ++frame_no);
3067 if (depth == frame_no) break;
3068 }
3069 if (validate_only) {
3070 values.validate();
3071 } else {
3072 tty->print_cr("[Describe stack layout]");
3073 values.print(this);
3074 }
3075 }
3076 #endif
3077
3078 void JavaThread::trace_stack_from(vframe* start_vf) {
3079 ResourceMark rm;
3080 int vframe_no = 1;
3081 for (vframe* f = start_vf; f; f = f->sender()) {
3082 if (f->is_java_frame()) {
3083 javaVFrame::cast(f)->print_activation(vframe_no++);
3084 } else {
3085 f->print();
3086 }
3087 if (vframe_no > StackPrintLimit) {
3088 tty->print_cr("...<more frames>...");
3089 return;
3090 }
3091 }
3092 }
3093
3094
3095 void JavaThread::trace_stack() {
3096 if (!has_last_Java_frame()) return;
3097 ResourceMark rm;
3098 HandleMark hm;
3099 RegisterMap reg_map(this);
3100 trace_stack_from(last_java_vframe(®_map));
3101 }
3102
3103
3104 #endif // PRODUCT
3105
3106
3107 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3108 assert(reg_map != NULL, "a map must be given");
3109 frame f = last_frame();
3110 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3111 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3112 }
3113 return NULL;
3114 }
3115
3116
3117 Klass* JavaThread::security_get_caller_class(int depth) {
3118 vframeStream vfst(this);
3119 vfst.security_get_caller_frame(depth);
3120 if (!vfst.at_end()) {
3121 return vfst.method()->method_holder();
3122 }
3123 return NULL;
3124 }
3125
3126 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3127 assert(thread->is_Compiler_thread(), "must be compiler thread");
3128 CompileBroker::compiler_thread_loop();
3129 }
3130
3131 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3132 NMethodSweeper::sweeper_loop();
3133 }
3134
3135 // Create a CompilerThread
3136 CompilerThread::CompilerThread(CompileQueue* queue,
3137 CompilerCounters* counters)
3138 : JavaThread(&compiler_thread_entry) {
3139 _env = NULL;
3140 _log = NULL;
3141 _task = NULL;
3142 _queue = queue;
3143 _counters = counters;
3144 _buffer_blob = NULL;
3145 _compiler = NULL;
3146
3147 #ifndef PRODUCT
3148 _ideal_graph_printer = NULL;
3149 #endif
3150 }
3151
3152 // Create sweeper thread
3153 CodeCacheSweeperThread::CodeCacheSweeperThread()
3154 : JavaThread(&sweeper_thread_entry) {
3155 _scanned_nmethod = NULL;
3156 }
3157 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3158 JavaThread::oops_do(f, cld_f, cf);
3159 if (_scanned_nmethod != NULL && cf != NULL) {
3160 // Safepoints can occur when the sweeper is scanning an nmethod so
3161 // process it here to make sure it isn't unloaded in the middle of
3162 // a scan.
3163 cf->do_code_blob(_scanned_nmethod);
3164 }
3165 }
3166
3167
3168 // ======= Threads ========
3169
3170 // The Threads class links together all active threads, and provides
3171 // operations over all threads. It is protected by its own Mutex
3172 // lock, which is also used in other contexts to protect thread
3173 // operations from having the thread being operated on from exiting
3174 // and going away unexpectedly (e.g., safepoint synchronization)
3175
3176 JavaThread* Threads::_thread_list = NULL;
3177 int Threads::_number_of_threads = 0;
3178 int Threads::_number_of_non_daemon_threads = 0;
3179 int Threads::_return_code = 0;
3180 size_t JavaThread::_stack_size_at_create = 0;
3181 #ifdef ASSERT
3182 bool Threads::_vm_complete = false;
3183 #endif
3184
3185 // All JavaThreads
3186 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3187
3188 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3189 void Threads::threads_do(ThreadClosure* tc) {
3190 assert_locked_or_safepoint(Threads_lock);
3191 // ALL_JAVA_THREADS iterates through all JavaThreads
3192 ALL_JAVA_THREADS(p) {
3193 tc->do_thread(p);
3194 }
3195 // Someday we could have a table or list of all non-JavaThreads.
3196 // For now, just manually iterate through them.
3197 tc->do_thread(VMThread::vm_thread());
3198 Universe::heap()->gc_threads_do(tc);
3199 WatcherThread *wt = WatcherThread::watcher_thread();
3200 // Strictly speaking, the following NULL check isn't sufficient to make sure
3201 // the data for WatcherThread is still valid upon being examined. However,
3202 // considering that WatchThread terminates when the VM is on the way to
3203 // exit at safepoint, the chance of the above is extremely small. The right
3204 // way to prevent termination of WatcherThread would be to acquire
3205 // Terminator_lock, but we can't do that without violating the lock rank
3206 // checking in some cases.
3207 if (wt != NULL) {
3208 tc->do_thread(wt);
3209 }
3210
3211 // If CompilerThreads ever become non-JavaThreads, add them here
3212 }
3213
3214
3215 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3216 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3217
3218 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3219 create_vm_init_libraries();
3220 }
3221
3222 initialize_class(vmSymbols::java_lang_String(), CHECK);
3223
3224 // Initialize java_lang.System (needed before creating the thread)
3225 initialize_class(vmSymbols::java_lang_System(), CHECK);
3226 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3227 Handle thread_group = create_initial_thread_group(CHECK);
3228 Universe::set_main_thread_group(thread_group());
3229 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3230 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3231 main_thread->set_threadObj(thread_object);
3232 // Set thread status to running since main thread has
3233 // been started and running.
3234 java_lang_Thread::set_thread_status(thread_object,
3235 java_lang_Thread::RUNNABLE);
3236
3237 // The VM creates & returns objects of this class. Make sure it's initialized.
3238 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3239
3240 // The VM preresolves methods to these classes. Make sure that they get initialized
3241 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3242 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3243 call_initializeSystemClass(CHECK);
3244
3245 // get the Java runtime name after java.lang.System is initialized
3246 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3247 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3248
3249 // an instance of OutOfMemory exception has been allocated earlier
3250 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3251 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3252 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3253 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3254 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3255 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3256 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3257 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3258 }
3259
3260 void Threads::initialize_jsr292_core_classes(TRAPS) {
3261 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3262 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3263 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3264 }
3265
3266 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3267 extern void JDK_Version_init();
3268
3269 // Check version
3270 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3271
3272 // Initialize the output stream module
3273 ostream_init();
3274
3275 // Process java launcher properties.
3276 Arguments::process_sun_java_launcher_properties(args);
3277
3278 // Initialize the os module before using TLS
3279 os::init();
3280
3281 // Initialize system properties.
3282 Arguments::init_system_properties();
3283
3284 // So that JDK version can be used as a discriminator when parsing arguments
3285 JDK_Version_init();
3286
3287 // Update/Initialize System properties after JDK version number is known
3288 Arguments::init_version_specific_system_properties();
3289
3290 // Parse arguments
3291 jint parse_result = Arguments::parse(args);
3292 if (parse_result != JNI_OK) return parse_result;
3293
3294 os::init_before_ergo();
3295
3296 jint ergo_result = Arguments::apply_ergo();
3297 if (ergo_result != JNI_OK) return ergo_result;
3298
3299 if (PauseAtStartup) {
3300 os::pause();
3301 }
3302
3303 HOTSPOT_VM_INIT_BEGIN();
3304
3305 // Record VM creation timing statistics
3306 TraceVmCreationTime create_vm_timer;
3307 create_vm_timer.start();
3308
3309 // Timing (must come after argument parsing)
3310 TraceTime timer("Create VM", TraceStartupTime);
3311
3312 // Initialize the os module after parsing the args
3313 jint os_init_2_result = os::init_2();
3314 if (os_init_2_result != JNI_OK) return os_init_2_result;
3315
3316 jint adjust_after_os_result = Arguments::adjust_after_os();
3317 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3318
3319 // initialize TLS
3320 ThreadLocalStorage::init();
3321
3322 // Initialize output stream logging
3323 ostream_init_log();
3324
3325 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3326 // Must be before create_vm_init_agents()
3327 if (Arguments::init_libraries_at_startup()) {
3328 convert_vm_init_libraries_to_agents();
3329 }
3330
3331 // Launch -agentlib/-agentpath and converted -Xrun agents
3332 if (Arguments::init_agents_at_startup()) {
3333 create_vm_init_agents();
3334 }
3335
3336 // Initialize Threads state
3337 _thread_list = NULL;
3338 _number_of_threads = 0;
3339 _number_of_non_daemon_threads = 0;
3340
3341 // Initialize global data structures and create system classes in heap
3342 vm_init_globals();
3343
3344 // Attach the main thread to this os thread
3345 JavaThread* main_thread = new JavaThread();
3346 main_thread->set_thread_state(_thread_in_vm);
3347 // must do this before set_active_handles and initialize_thread_local_storage
3348 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3349 // change the stack size recorded here to one based on the java thread
3350 // stacksize. This adjusted size is what is used to figure the placement
3351 // of the guard pages.
3352 main_thread->record_stack_base_and_size();
3353 main_thread->initialize_thread_local_storage();
3354
3355 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3356
3357 if (!main_thread->set_as_starting_thread()) {
3358 vm_shutdown_during_initialization(
3359 "Failed necessary internal allocation. Out of swap space");
3360 delete main_thread;
3361 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3362 return JNI_ENOMEM;
3363 }
3364
3365 // Enable guard page *after* os::create_main_thread(), otherwise it would
3366 // crash Linux VM, see notes in os_linux.cpp.
3367 main_thread->create_stack_guard_pages();
3368
3369 // Initialize Java-Level synchronization subsystem
3370 ObjectMonitor::Initialize();
3371
3372 // Initialize global modules
3373 jint status = init_globals();
3374 if (status != JNI_OK) {
3375 delete main_thread;
3376 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3377 return status;
3378 }
3379
3380 // Should be done after the heap is fully created
3381 main_thread->cache_global_variables();
3382
3383 HandleMark hm;
3384
3385 { MutexLocker mu(Threads_lock);
3386 Threads::add(main_thread);
3387 }
3388
3389 // Any JVMTI raw monitors entered in onload will transition into
3390 // real raw monitor. VM is setup enough here for raw monitor enter.
3391 JvmtiExport::transition_pending_onload_raw_monitors();
3392
3393 // Create the VMThread
3394 { TraceTime timer("Start VMThread", TraceStartupTime);
3395 VMThread::create();
3396 Thread* vmthread = VMThread::vm_thread();
3397
3398 if (!os::create_thread(vmthread, os::vm_thread)) {
3399 vm_exit_during_initialization("Cannot create VM thread. "
3400 "Out of system resources.");
3401 }
3402
3403 // Wait for the VM thread to become ready, and VMThread::run to initialize
3404 // Monitors can have spurious returns, must always check another state flag
3405 {
3406 MutexLocker ml(Notify_lock);
3407 os::start_thread(vmthread);
3408 while (vmthread->active_handles() == NULL) {
3409 Notify_lock->wait();
3410 }
3411 }
3412 }
3413
3414 assert(Universe::is_fully_initialized(), "not initialized");
3415 if (VerifyDuringStartup) {
3416 // Make sure we're starting with a clean slate.
3417 VM_Verify verify_op;
3418 VMThread::execute(&verify_op);
3419 }
3420
3421 Thread* THREAD = Thread::current();
3422
3423 // At this point, the Universe is initialized, but we have not executed
3424 // any byte code. Now is a good time (the only time) to dump out the
3425 // internal state of the JVM for sharing.
3426 if (DumpSharedSpaces) {
3427 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3428 ShouldNotReachHere();
3429 }
3430
3431 // Always call even when there are not JVMTI environments yet, since environments
3432 // may be attached late and JVMTI must track phases of VM execution
3433 JvmtiExport::enter_start_phase();
3434
3435 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3436 JvmtiExport::post_vm_start();
3437
3438 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3439
3440 // We need this for ClassDataSharing - the initial vm.info property is set
3441 // with the default value of CDS "sharing" which may be reset through
3442 // command line options.
3443 reset_vm_info_property(CHECK_JNI_ERR);
3444
3445 quicken_jni_functions();
3446
3447 // Must be run after init_ft which initializes ft_enabled
3448 if (TRACE_INITIALIZE() != JNI_OK) {
3449 vm_exit_during_initialization("Failed to initialize tracing backend");
3450 }
3451
3452 // Set flag that basic initialization has completed. Used by exceptions and various
3453 // debug stuff, that does not work until all basic classes have been initialized.
3454 set_init_completed();
3455
3456 Metaspace::post_initialize();
3457
3458 HOTSPOT_VM_INIT_END();
3459
3460 // record VM initialization completion time
3461 #if INCLUDE_MANAGEMENT
3462 Management::record_vm_init_completed();
3463 #endif // INCLUDE_MANAGEMENT
3464
3465 // Compute system loader. Note that this has to occur after set_init_completed, since
3466 // valid exceptions may be thrown in the process.
3467 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3468 // set_init_completed has just been called, causing exceptions not to be shortcut
3469 // anymore. We call vm_exit_during_initialization directly instead.
3470 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3471
3472 #if INCLUDE_ALL_GCS
3473 // Support for ConcurrentMarkSweep. This should be cleaned up
3474 // and better encapsulated. The ugly nested if test would go away
3475 // once things are properly refactored. XXX YSR
3476 if (UseConcMarkSweepGC || UseG1GC) {
3477 if (UseConcMarkSweepGC) {
3478 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3479 } else {
3480 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3481 }
3482 }
3483 #endif // INCLUDE_ALL_GCS
3484
3485 // Always call even when there are not JVMTI environments yet, since environments
3486 // may be attached late and JVMTI must track phases of VM execution
3487 JvmtiExport::enter_live_phase();
3488
3489 // Signal Dispatcher needs to be started before VMInit event is posted
3490 os::signal_init();
3491
3492 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3493 if (!DisableAttachMechanism) {
3494 AttachListener::vm_start();
3495 if (StartAttachListener || AttachListener::init_at_startup()) {
3496 AttachListener::init();
3497 }
3498 }
3499
3500 // Launch -Xrun agents
3501 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3502 // back-end can launch with -Xdebug -Xrunjdwp.
3503 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3504 create_vm_init_libraries();
3505 }
3506
3507 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3508 JvmtiExport::post_vm_initialized();
3509
3510 if (TRACE_START() != JNI_OK) {
3511 vm_exit_during_initialization("Failed to start tracing backend.");
3512 }
3513
3514 if (CleanChunkPoolAsync) {
3515 Chunk::start_chunk_pool_cleaner_task();
3516 }
3517
3518 // initialize compiler(s)
3519 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3520 CompileBroker::compilation_init();
3521 #endif
3522
3523 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3524 // It is done after compilers are initialized, because otherwise compilations of
3525 // signature polymorphic MH intrinsics can be missed
3526 // (see SystemDictionary::find_method_handle_intrinsic).
3527 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3528
3529 #if INCLUDE_MANAGEMENT
3530 Management::initialize(THREAD);
3531
3532 if (HAS_PENDING_EXCEPTION) {
3533 // management agent fails to start possibly due to
3534 // configuration problem and is responsible for printing
3535 // stack trace if appropriate. Simply exit VM.
3536 vm_exit(1);
3537 }
3538 #endif // INCLUDE_MANAGEMENT
3539
3540 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3541 if (MemProfiling) MemProfiler::engage();
3542 StatSampler::engage();
3543 if (CheckJNICalls) JniPeriodicChecker::engage();
3544
3545 BiasedLocking::init();
3546
3547 #if INCLUDE_RTM_OPT
3548 RTMLockingCounters::init();
3549 #endif
3550
3551 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3552 call_postVMInitHook(THREAD);
3553 // The Java side of PostVMInitHook.run must deal with all
3554 // exceptions and provide means of diagnosis.
3555 if (HAS_PENDING_EXCEPTION) {
3556 CLEAR_PENDING_EXCEPTION;
3557 }
3558 }
3559
3560 {
3561 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3562 // Make sure the watcher thread can be started by WatcherThread::start()
3563 // or by dynamic enrollment.
3564 WatcherThread::make_startable();
3565 // Start up the WatcherThread if there are any periodic tasks
3566 // NOTE: All PeriodicTasks should be registered by now. If they
3567 // aren't, late joiners might appear to start slowly (we might
3568 // take a while to process their first tick).
3569 if (PeriodicTask::num_tasks() > 0) {
3570 WatcherThread::start();
3571 }
3572 }
3573
3574 create_vm_timer.end();
3575 #ifdef ASSERT
3576 _vm_complete = true;
3577 #endif
3578 return JNI_OK;
3579 }
3580
3581 // type for the Agent_OnLoad and JVM_OnLoad entry points
3582 extern "C" {
3583 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3584 }
3585 // Find a command line agent library and return its entry point for
3586 // -agentlib: -agentpath: -Xrun
3587 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3588 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3589 const char *on_load_symbols[],
3590 size_t num_symbol_entries) {
3591 OnLoadEntry_t on_load_entry = NULL;
3592 void *library = NULL;
3593
3594 if (!agent->valid()) {
3595 char buffer[JVM_MAXPATHLEN];
3596 char ebuf[1024] = "";
3597 const char *name = agent->name();
3598 const char *msg = "Could not find agent library ";
3599
3600 // First check to see if agent is statically linked into executable
3601 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3602 library = agent->os_lib();
3603 } else if (agent->is_absolute_path()) {
3604 library = os::dll_load(name, ebuf, sizeof ebuf);
3605 if (library == NULL) {
3606 const char *sub_msg = " in absolute path, with error: ";
3607 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3608 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3609 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3610 // If we can't find the agent, exit.
3611 vm_exit_during_initialization(buf, NULL);
3612 FREE_C_HEAP_ARRAY(char, buf);
3613 }
3614 } else {
3615 // Try to load the agent from the standard dll directory
3616 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3617 name)) {
3618 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3619 }
3620 if (library == NULL) { // Try the local directory
3621 char ns[1] = {0};
3622 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3623 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3624 }
3625 if (library == NULL) {
3626 const char *sub_msg = " on the library path, with error: ";
3627 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3628 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3629 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3630 // If we can't find the agent, exit.
3631 vm_exit_during_initialization(buf, NULL);
3632 FREE_C_HEAP_ARRAY(char, buf);
3633 }
3634 }
3635 }
3636 agent->set_os_lib(library);
3637 agent->set_valid();
3638 }
3639
3640 // Find the OnLoad function.
3641 on_load_entry =
3642 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3643 false,
3644 on_load_symbols,
3645 num_symbol_entries));
3646 return on_load_entry;
3647 }
3648
3649 // Find the JVM_OnLoad entry point
3650 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3651 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3652 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3653 }
3654
3655 // Find the Agent_OnLoad entry point
3656 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3657 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3658 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3659 }
3660
3661 // For backwards compatibility with -Xrun
3662 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3663 // treated like -agentpath:
3664 // Must be called before agent libraries are created
3665 void Threads::convert_vm_init_libraries_to_agents() {
3666 AgentLibrary* agent;
3667 AgentLibrary* next;
3668
3669 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3670 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3671 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3672
3673 // If there is an JVM_OnLoad function it will get called later,
3674 // otherwise see if there is an Agent_OnLoad
3675 if (on_load_entry == NULL) {
3676 on_load_entry = lookup_agent_on_load(agent);
3677 if (on_load_entry != NULL) {
3678 // switch it to the agent list -- so that Agent_OnLoad will be called,
3679 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3680 Arguments::convert_library_to_agent(agent);
3681 } else {
3682 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3683 }
3684 }
3685 }
3686 }
3687
3688 // Create agents for -agentlib: -agentpath: and converted -Xrun
3689 // Invokes Agent_OnLoad
3690 // Called very early -- before JavaThreads exist
3691 void Threads::create_vm_init_agents() {
3692 extern struct JavaVM_ main_vm;
3693 AgentLibrary* agent;
3694
3695 JvmtiExport::enter_onload_phase();
3696
3697 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3698 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3699
3700 if (on_load_entry != NULL) {
3701 // Invoke the Agent_OnLoad function
3702 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3703 if (err != JNI_OK) {
3704 vm_exit_during_initialization("agent library failed to init", agent->name());
3705 }
3706 } else {
3707 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3708 }
3709 }
3710 JvmtiExport::enter_primordial_phase();
3711 }
3712
3713 extern "C" {
3714 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3715 }
3716
3717 void Threads::shutdown_vm_agents() {
3718 // Send any Agent_OnUnload notifications
3719 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3720 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3721 extern struct JavaVM_ main_vm;
3722 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3723
3724 // Find the Agent_OnUnload function.
3725 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3726 os::find_agent_function(agent,
3727 false,
3728 on_unload_symbols,
3729 num_symbol_entries));
3730
3731 // Invoke the Agent_OnUnload function
3732 if (unload_entry != NULL) {
3733 JavaThread* thread = JavaThread::current();
3734 ThreadToNativeFromVM ttn(thread);
3735 HandleMark hm(thread);
3736 (*unload_entry)(&main_vm);
3737 }
3738 }
3739 }
3740
3741 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3742 // Invokes JVM_OnLoad
3743 void Threads::create_vm_init_libraries() {
3744 extern struct JavaVM_ main_vm;
3745 AgentLibrary* agent;
3746
3747 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3748 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3749
3750 if (on_load_entry != NULL) {
3751 // Invoke the JVM_OnLoad function
3752 JavaThread* thread = JavaThread::current();
3753 ThreadToNativeFromVM ttn(thread);
3754 HandleMark hm(thread);
3755 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3756 if (err != JNI_OK) {
3757 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3758 }
3759 } else {
3760 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3761 }
3762 }
3763 }
3764
3765 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3766 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3767
3768 JavaThread* java_thread = NULL;
3769 // Sequential search for now. Need to do better optimization later.
3770 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3771 oop tobj = thread->threadObj();
3772 if (!thread->is_exiting() &&
3773 tobj != NULL &&
3774 java_tid == java_lang_Thread::thread_id(tobj)) {
3775 java_thread = thread;
3776 break;
3777 }
3778 }
3779 return java_thread;
3780 }
3781
3782
3783 // Last thread running calls java.lang.Shutdown.shutdown()
3784 void JavaThread::invoke_shutdown_hooks() {
3785 HandleMark hm(this);
3786
3787 // We could get here with a pending exception, if so clear it now.
3788 if (this->has_pending_exception()) {
3789 this->clear_pending_exception();
3790 }
3791
3792 EXCEPTION_MARK;
3793 Klass* k =
3794 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3795 THREAD);
3796 if (k != NULL) {
3797 // SystemDictionary::resolve_or_null will return null if there was
3798 // an exception. If we cannot load the Shutdown class, just don't
3799 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3800 // and finalizers (if runFinalizersOnExit is set) won't be run.
3801 // Note that if a shutdown hook was registered or runFinalizersOnExit
3802 // was called, the Shutdown class would have already been loaded
3803 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3804 instanceKlassHandle shutdown_klass (THREAD, k);
3805 JavaValue result(T_VOID);
3806 JavaCalls::call_static(&result,
3807 shutdown_klass,
3808 vmSymbols::shutdown_method_name(),
3809 vmSymbols::void_method_signature(),
3810 THREAD);
3811 }
3812 CLEAR_PENDING_EXCEPTION;
3813 }
3814
3815 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3816 // the program falls off the end of main(). Another VM exit path is through
3817 // vm_exit() when the program calls System.exit() to return a value or when
3818 // there is a serious error in VM. The two shutdown paths are not exactly
3819 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3820 // and VM_Exit op at VM level.
3821 //
3822 // Shutdown sequence:
3823 // + Shutdown native memory tracking if it is on
3824 // + Wait until we are the last non-daemon thread to execute
3825 // <-- every thing is still working at this moment -->
3826 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3827 // shutdown hooks, run finalizers if finalization-on-exit
3828 // + Call before_exit(), prepare for VM exit
3829 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3830 // currently the only user of this mechanism is File.deleteOnExit())
3831 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3832 // post thread end and vm death events to JVMTI,
3833 // stop signal thread
3834 // + Call JavaThread::exit(), it will:
3835 // > release JNI handle blocks, remove stack guard pages
3836 // > remove this thread from Threads list
3837 // <-- no more Java code from this thread after this point -->
3838 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3839 // the compiler threads at safepoint
3840 // <-- do not use anything that could get blocked by Safepoint -->
3841 // + Disable tracing at JNI/JVM barriers
3842 // + Set _vm_exited flag for threads that are still running native code
3843 // + Delete this thread
3844 // + Call exit_globals()
3845 // > deletes tty
3846 // > deletes PerfMemory resources
3847 // + Return to caller
3848
3849 bool Threads::destroy_vm() {
3850 JavaThread* thread = JavaThread::current();
3851
3852 #ifdef ASSERT
3853 _vm_complete = false;
3854 #endif
3855 // Wait until we are the last non-daemon thread to execute
3856 { MutexLocker nu(Threads_lock);
3857 while (Threads::number_of_non_daemon_threads() > 1)
3858 // This wait should make safepoint checks, wait without a timeout,
3859 // and wait as a suspend-equivalent condition.
3860 //
3861 // Note: If the FlatProfiler is running and this thread is waiting
3862 // for another non-daemon thread to finish, then the FlatProfiler
3863 // is waiting for the external suspend request on this thread to
3864 // complete. wait_for_ext_suspend_completion() will eventually
3865 // timeout, but that takes time. Making this wait a suspend-
3866 // equivalent condition solves that timeout problem.
3867 //
3868 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3869 Mutex::_as_suspend_equivalent_flag);
3870 }
3871
3872 // Hang forever on exit if we are reporting an error.
3873 if (ShowMessageBoxOnError && is_error_reported()) {
3874 os::infinite_sleep();
3875 }
3876 os::wait_for_keypress_at_exit();
3877
3878 // run Java level shutdown hooks
3879 thread->invoke_shutdown_hooks();
3880
3881 before_exit(thread);
3882
3883 thread->exit(true);
3884
3885 // Stop VM thread.
3886 {
3887 // 4945125 The vm thread comes to a safepoint during exit.
3888 // GC vm_operations can get caught at the safepoint, and the
3889 // heap is unparseable if they are caught. Grab the Heap_lock
3890 // to prevent this. The GC vm_operations will not be able to
3891 // queue until after the vm thread is dead. After this point,
3892 // we'll never emerge out of the safepoint before the VM exits.
3893
3894 MutexLocker ml(Heap_lock);
3895
3896 VMThread::wait_for_vm_thread_exit();
3897 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3898 VMThread::destroy();
3899 }
3900
3901 // clean up ideal graph printers
3902 #if defined(COMPILER2) && !defined(PRODUCT)
3903 IdealGraphPrinter::clean_up();
3904 #endif
3905
3906 // Now, all Java threads are gone except daemon threads. Daemon threads
3907 // running Java code or in VM are stopped by the Safepoint. However,
3908 // daemon threads executing native code are still running. But they
3909 // will be stopped at native=>Java/VM barriers. Note that we can't
3910 // simply kill or suspend them, as it is inherently deadlock-prone.
3911
3912 #ifndef PRODUCT
3913 // disable function tracing at JNI/JVM barriers
3914 TraceJNICalls = false;
3915 TraceJVMCalls = false;
3916 TraceRuntimeCalls = false;
3917 #endif
3918
3919 VM_Exit::set_vm_exited();
3920
3921 notify_vm_shutdown();
3922
3923 delete thread;
3924
3925 // exit_globals() will delete tty
3926 exit_globals();
3927
3928 return true;
3929 }
3930
3931
3932 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3933 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3934 return is_supported_jni_version(version);
3935 }
3936
3937
3938 jboolean Threads::is_supported_jni_version(jint version) {
3939 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3940 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3941 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3942 if (version == JNI_VERSION_1_8) return JNI_TRUE;
3943 return JNI_FALSE;
3944 }
3945
3946
3947 void Threads::add(JavaThread* p, bool force_daemon) {
3948 // The threads lock must be owned at this point
3949 assert_locked_or_safepoint(Threads_lock);
3950
3951 // See the comment for this method in thread.hpp for its purpose and
3952 // why it is called here.
3953 p->initialize_queues();
3954 p->set_next(_thread_list);
3955 _thread_list = p;
3956 _number_of_threads++;
3957 oop threadObj = p->threadObj();
3958 bool daemon = true;
3959 // Bootstrapping problem: threadObj can be null for initial
3960 // JavaThread (or for threads attached via JNI)
3961 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3962 _number_of_non_daemon_threads++;
3963 daemon = false;
3964 }
3965
3966 ThreadService::add_thread(p, daemon);
3967
3968 // Possible GC point.
3969 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3970 }
3971
3972 void Threads::remove(JavaThread* p) {
3973 // Extra scope needed for Thread_lock, so we can check
3974 // that we do not remove thread without safepoint code notice
3975 { MutexLocker ml(Threads_lock);
3976
3977 assert(includes(p), "p must be present");
3978
3979 JavaThread* current = _thread_list;
3980 JavaThread* prev = NULL;
3981
3982 while (current != p) {
3983 prev = current;
3984 current = current->next();
3985 }
3986
3987 if (prev) {
3988 prev->set_next(current->next());
3989 } else {
3990 _thread_list = p->next();
3991 }
3992 _number_of_threads--;
3993 oop threadObj = p->threadObj();
3994 bool daemon = true;
3995 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3996 _number_of_non_daemon_threads--;
3997 daemon = false;
3998
3999 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4000 // on destroy_vm will wake up.
4001 if (number_of_non_daemon_threads() == 1) {
4002 Threads_lock->notify_all();
4003 }
4004 }
4005 ThreadService::remove_thread(p, daemon);
4006
4007 // Make sure that safepoint code disregard this thread. This is needed since
4008 // the thread might mess around with locks after this point. This can cause it
4009 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4010 // of this thread since it is removed from the queue.
4011 p->set_terminated_value();
4012 } // unlock Threads_lock
4013
4014 // Since Events::log uses a lock, we grab it outside the Threads_lock
4015 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4016 }
4017
4018 // Threads_lock must be held when this is called (or must be called during a safepoint)
4019 bool Threads::includes(JavaThread* p) {
4020 assert(Threads_lock->is_locked(), "sanity check");
4021 ALL_JAVA_THREADS(q) {
4022 if (q == p) {
4023 return true;
4024 }
4025 }
4026 return false;
4027 }
4028
4029 // Operations on the Threads list for GC. These are not explicitly locked,
4030 // but the garbage collector must provide a safe context for them to run.
4031 // In particular, these things should never be called when the Threads_lock
4032 // is held by some other thread. (Note: the Safepoint abstraction also
4033 // uses the Threads_lock to guarantee this property. It also makes sure that
4034 // all threads gets blocked when exiting or starting).
4035
4036 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4037 ALL_JAVA_THREADS(p) {
4038 p->oops_do(f, cld_f, cf);
4039 }
4040 VMThread::vm_thread()->oops_do(f, cld_f, cf);
4041 }
4042
4043 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4044 // Introduce a mechanism allowing parallel threads to claim threads as
4045 // root groups. Overhead should be small enough to use all the time,
4046 // even in sequential code.
4047 SharedHeap* sh = SharedHeap::heap();
4048 // Cannot yet substitute active_workers for n_par_threads
4049 // because of G1CollectedHeap::verify() use of
4050 // SharedHeap::process_roots(). n_par_threads == 0 will
4051 // turn off parallelism in process_roots while active_workers
4052 // is being used for parallelism elsewhere.
4053 bool is_par = sh->n_par_threads() > 0;
4054 assert(!is_par ||
4055 (SharedHeap::heap()->n_par_threads() ==
4056 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4057 int cp = SharedHeap::heap()->strong_roots_parity();
4058 ALL_JAVA_THREADS(p) {
4059 if (p->claim_oops_do(is_par, cp)) {
4060 p->oops_do(f, cld_f, cf);
4061 }
4062 }
4063 VMThread* vmt = VMThread::vm_thread();
4064 if (vmt->claim_oops_do(is_par, cp)) {
4065 vmt->oops_do(f, cld_f, cf);
4066 }
4067 }
4068
4069 #if INCLUDE_ALL_GCS
4070 // Used by ParallelScavenge
4071 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4072 ALL_JAVA_THREADS(p) {
4073 q->enqueue(new ThreadRootsTask(p));
4074 }
4075 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4076 }
4077
4078 // Used by Parallel Old
4079 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4080 ALL_JAVA_THREADS(p) {
4081 q->enqueue(new ThreadRootsMarkingTask(p));
4082 }
4083 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4084 }
4085 #endif // INCLUDE_ALL_GCS
4086
4087 void Threads::nmethods_do(CodeBlobClosure* cf) {
4088 ALL_JAVA_THREADS(p) {
4089 p->nmethods_do(cf);
4090 }
4091 VMThread::vm_thread()->nmethods_do(cf);
4092 }
4093
4094 void Threads::metadata_do(void f(Metadata*)) {
4095 ALL_JAVA_THREADS(p) {
4096 p->metadata_do(f);
4097 }
4098 }
4099
4100 void Threads::deoptimized_wrt_marked_nmethods() {
4101 ALL_JAVA_THREADS(p) {
4102 p->deoptimized_wrt_marked_nmethods();
4103 }
4104 }
4105
4106
4107 // Get count Java threads that are waiting to enter the specified monitor.
4108 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4109 address monitor,
4110 bool doLock) {
4111 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4112 "must grab Threads_lock or be at safepoint");
4113 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4114
4115 int i = 0;
4116 {
4117 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4118 ALL_JAVA_THREADS(p) {
4119 if (p->is_Compiler_thread()) continue;
4120
4121 address pending = (address)p->current_pending_monitor();
4122 if (pending == monitor) { // found a match
4123 if (i < count) result->append(p); // save the first count matches
4124 i++;
4125 }
4126 }
4127 }
4128 return result;
4129 }
4130
4131
4132 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4133 bool doLock) {
4134 assert(doLock ||
4135 Threads_lock->owned_by_self() ||
4136 SafepointSynchronize::is_at_safepoint(),
4137 "must grab Threads_lock or be at safepoint");
4138
4139 // NULL owner means not locked so we can skip the search
4140 if (owner == NULL) return NULL;
4141
4142 {
4143 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4144 ALL_JAVA_THREADS(p) {
4145 // first, see if owner is the address of a Java thread
4146 if (owner == (address)p) return p;
4147 }
4148 }
4149 // Cannot assert on lack of success here since this function may be
4150 // used by code that is trying to report useful problem information
4151 // like deadlock detection.
4152 if (UseHeavyMonitors) return NULL;
4153
4154 // If we didn't find a matching Java thread and we didn't force use of
4155 // heavyweight monitors, then the owner is the stack address of the
4156 // Lock Word in the owning Java thread's stack.
4157 //
4158 JavaThread* the_owner = NULL;
4159 {
4160 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4161 ALL_JAVA_THREADS(q) {
4162 if (q->is_lock_owned(owner)) {
4163 the_owner = q;
4164 break;
4165 }
4166 }
4167 }
4168 // cannot assert on lack of success here; see above comment
4169 return the_owner;
4170 }
4171
4172 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4173 void Threads::print_on(outputStream* st, bool print_stacks,
4174 bool internal_format, bool print_concurrent_locks) {
4175 char buf[32];
4176 st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4177
4178 st->print_cr("Full thread dump %s (%s %s):",
4179 Abstract_VM_Version::vm_name(),
4180 Abstract_VM_Version::vm_release(),
4181 Abstract_VM_Version::vm_info_string());
4182 st->cr();
4183
4184 #if INCLUDE_ALL_GCS
4185 // Dump concurrent locks
4186 ConcurrentLocksDump concurrent_locks;
4187 if (print_concurrent_locks) {
4188 concurrent_locks.dump_at_safepoint();
4189 }
4190 #endif // INCLUDE_ALL_GCS
4191
4192 ALL_JAVA_THREADS(p) {
4193 ResourceMark rm;
4194 p->print_on(st);
4195 if (print_stacks) {
4196 if (internal_format) {
4197 p->trace_stack();
4198 } else {
4199 p->print_stack_on(st);
4200 }
4201 }
4202 st->cr();
4203 #if INCLUDE_ALL_GCS
4204 if (print_concurrent_locks) {
4205 concurrent_locks.print_locks_on(p, st);
4206 }
4207 #endif // INCLUDE_ALL_GCS
4208 }
4209
4210 VMThread::vm_thread()->print_on(st);
4211 st->cr();
4212 Universe::heap()->print_gc_threads_on(st);
4213 WatcherThread* wt = WatcherThread::watcher_thread();
4214 if (wt != NULL) {
4215 wt->print_on(st);
4216 st->cr();
4217 }
4218 CompileBroker::print_compiler_threads_on(st);
4219 st->flush();
4220 }
4221
4222 // Threads::print_on_error() is called by fatal error handler. It's possible
4223 // that VM is not at safepoint and/or current thread is inside signal handler.
4224 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4225 // memory (even in resource area), it might deadlock the error handler.
4226 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4227 int buflen) {
4228 bool found_current = false;
4229 st->print_cr("Java Threads: ( => current thread )");
4230 ALL_JAVA_THREADS(thread) {
4231 bool is_current = (current == thread);
4232 found_current = found_current || is_current;
4233
4234 st->print("%s", is_current ? "=>" : " ");
4235
4236 st->print(PTR_FORMAT, thread);
4237 st->print(" ");
4238 thread->print_on_error(st, buf, buflen);
4239 st->cr();
4240 }
4241 st->cr();
4242
4243 st->print_cr("Other Threads:");
4244 if (VMThread::vm_thread()) {
4245 bool is_current = (current == VMThread::vm_thread());
4246 found_current = found_current || is_current;
4247 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4248
4249 st->print(PTR_FORMAT, VMThread::vm_thread());
4250 st->print(" ");
4251 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4252 st->cr();
4253 }
4254 WatcherThread* wt = WatcherThread::watcher_thread();
4255 if (wt != NULL) {
4256 bool is_current = (current == wt);
4257 found_current = found_current || is_current;
4258 st->print("%s", is_current ? "=>" : " ");
4259
4260 st->print(PTR_FORMAT, wt);
4261 st->print(" ");
4262 wt->print_on_error(st, buf, buflen);
4263 st->cr();
4264 }
4265 if (!found_current) {
4266 st->cr();
4267 st->print("=>" PTR_FORMAT " (exited) ", current);
4268 current->print_on_error(st, buf, buflen);
4269 st->cr();
4270 }
4271 }
4272
4273 // Internal SpinLock and Mutex
4274 // Based on ParkEvent
4275
4276 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4277 //
4278 // We employ SpinLocks _only for low-contention, fixed-length
4279 // short-duration critical sections where we're concerned
4280 // about native mutex_t or HotSpot Mutex:: latency.
4281 // The mux construct provides a spin-then-block mutual exclusion
4282 // mechanism.
4283 //
4284 // Testing has shown that contention on the ListLock guarding gFreeList
4285 // is common. If we implement ListLock as a simple SpinLock it's common
4286 // for the JVM to devolve to yielding with little progress. This is true
4287 // despite the fact that the critical sections protected by ListLock are
4288 // extremely short.
4289 //
4290 // TODO-FIXME: ListLock should be of type SpinLock.
4291 // We should make this a 1st-class type, integrated into the lock
4292 // hierarchy as leaf-locks. Critically, the SpinLock structure
4293 // should have sufficient padding to avoid false-sharing and excessive
4294 // cache-coherency traffic.
4295
4296
4297 typedef volatile int SpinLockT;
4298
4299 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4300 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4301 return; // normal fast-path return
4302 }
4303
4304 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4305 TEVENT(SpinAcquire - ctx);
4306 int ctr = 0;
4307 int Yields = 0;
4308 for (;;) {
4309 while (*adr != 0) {
4310 ++ctr;
4311 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4312 if (Yields > 5) {
4313 os::naked_short_sleep(1);
4314 } else {
4315 os::naked_yield();
4316 ++Yields;
4317 }
4318 } else {
4319 SpinPause();
4320 }
4321 }
4322 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4323 }
4324 }
4325
4326 void Thread::SpinRelease(volatile int * adr) {
4327 assert(*adr != 0, "invariant");
4328 OrderAccess::fence(); // guarantee at least release consistency.
4329 // Roach-motel semantics.
4330 // It's safe if subsequent LDs and STs float "up" into the critical section,
4331 // but prior LDs and STs within the critical section can't be allowed
4332 // to reorder or float past the ST that releases the lock.
4333 // Loads and stores in the critical section - which appear in program
4334 // order before the store that releases the lock - must also appear
4335 // before the store that releases the lock in memory visibility order.
4336 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4337 // the ST of 0 into the lock-word which releases the lock, so fence
4338 // more than covers this on all platforms.
4339 *adr = 0;
4340 }
4341
4342 // muxAcquire and muxRelease:
4343 //
4344 // * muxAcquire and muxRelease support a single-word lock-word construct.
4345 // The LSB of the word is set IFF the lock is held.
4346 // The remainder of the word points to the head of a singly-linked list
4347 // of threads blocked on the lock.
4348 //
4349 // * The current implementation of muxAcquire-muxRelease uses its own
4350 // dedicated Thread._MuxEvent instance. If we're interested in
4351 // minimizing the peak number of extant ParkEvent instances then
4352 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4353 // as certain invariants were satisfied. Specifically, care would need
4354 // to be taken with regards to consuming unpark() "permits".
4355 // A safe rule of thumb is that a thread would never call muxAcquire()
4356 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4357 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4358 // consume an unpark() permit intended for monitorenter, for instance.
4359 // One way around this would be to widen the restricted-range semaphore
4360 // implemented in park(). Another alternative would be to provide
4361 // multiple instances of the PlatformEvent() for each thread. One
4362 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4363 //
4364 // * Usage:
4365 // -- Only as leaf locks
4366 // -- for short-term locking only as muxAcquire does not perform
4367 // thread state transitions.
4368 //
4369 // Alternatives:
4370 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4371 // but with parking or spin-then-park instead of pure spinning.
4372 // * Use Taura-Oyama-Yonenzawa locks.
4373 // * It's possible to construct a 1-0 lock if we encode the lockword as
4374 // (List,LockByte). Acquire will CAS the full lockword while Release
4375 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4376 // acquiring threads use timers (ParkTimed) to detect and recover from
4377 // the stranding window. Thread/Node structures must be aligned on 256-byte
4378 // boundaries by using placement-new.
4379 // * Augment MCS with advisory back-link fields maintained with CAS().
4380 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4381 // The validity of the backlinks must be ratified before we trust the value.
4382 // If the backlinks are invalid the exiting thread must back-track through the
4383 // the forward links, which are always trustworthy.
4384 // * Add a successor indication. The LockWord is currently encoded as
4385 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4386 // to provide the usual futile-wakeup optimization.
4387 // See RTStt for details.
4388 // * Consider schedctl.sc_nopreempt to cover the critical section.
4389 //
4390
4391
4392 typedef volatile intptr_t MutexT; // Mux Lock-word
4393 enum MuxBits { LOCKBIT = 1 };
4394
4395 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4396 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4397 if (w == 0) return;
4398 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4399 return;
4400 }
4401
4402 TEVENT(muxAcquire - Contention);
4403 ParkEvent * const Self = Thread::current()->_MuxEvent;
4404 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4405 for (;;) {
4406 int its = (os::is_MP() ? 100 : 0) + 1;
4407
4408 // Optional spin phase: spin-then-park strategy
4409 while (--its >= 0) {
4410 w = *Lock;
4411 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4412 return;
4413 }
4414 }
4415
4416 Self->reset();
4417 Self->OnList = intptr_t(Lock);
4418 // The following fence() isn't _strictly necessary as the subsequent
4419 // CAS() both serializes execution and ratifies the fetched *Lock value.
4420 OrderAccess::fence();
4421 for (;;) {
4422 w = *Lock;
4423 if ((w & LOCKBIT) == 0) {
4424 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4425 Self->OnList = 0; // hygiene - allows stronger asserts
4426 return;
4427 }
4428 continue; // Interference -- *Lock changed -- Just retry
4429 }
4430 assert(w & LOCKBIT, "invariant");
4431 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4432 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4433 }
4434
4435 while (Self->OnList != 0) {
4436 Self->park();
4437 }
4438 }
4439 }
4440
4441 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4442 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4443 if (w == 0) return;
4444 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4445 return;
4446 }
4447
4448 TEVENT(muxAcquire - Contention);
4449 ParkEvent * ReleaseAfter = NULL;
4450 if (ev == NULL) {
4451 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4452 }
4453 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4454 for (;;) {
4455 guarantee(ev->OnList == 0, "invariant");
4456 int its = (os::is_MP() ? 100 : 0) + 1;
4457
4458 // Optional spin phase: spin-then-park strategy
4459 while (--its >= 0) {
4460 w = *Lock;
4461 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4462 if (ReleaseAfter != NULL) {
4463 ParkEvent::Release(ReleaseAfter);
4464 }
4465 return;
4466 }
4467 }
4468
4469 ev->reset();
4470 ev->OnList = intptr_t(Lock);
4471 // The following fence() isn't _strictly necessary as the subsequent
4472 // CAS() both serializes execution and ratifies the fetched *Lock value.
4473 OrderAccess::fence();
4474 for (;;) {
4475 w = *Lock;
4476 if ((w & LOCKBIT) == 0) {
4477 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4478 ev->OnList = 0;
4479 // We call ::Release while holding the outer lock, thus
4480 // artificially lengthening the critical section.
4481 // Consider deferring the ::Release() until the subsequent unlock(),
4482 // after we've dropped the outer lock.
4483 if (ReleaseAfter != NULL) {
4484 ParkEvent::Release(ReleaseAfter);
4485 }
4486 return;
4487 }
4488 continue; // Interference -- *Lock changed -- Just retry
4489 }
4490 assert(w & LOCKBIT, "invariant");
4491 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4492 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4493 }
4494
4495 while (ev->OnList != 0) {
4496 ev->park();
4497 }
4498 }
4499 }
4500
4501 // Release() must extract a successor from the list and then wake that thread.
4502 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4503 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4504 // Release() would :
4505 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4506 // (B) Extract a successor from the private list "in-hand"
4507 // (C) attempt to CAS() the residual back into *Lock over null.
4508 // If there were any newly arrived threads and the CAS() would fail.
4509 // In that case Release() would detach the RATs, re-merge the list in-hand
4510 // with the RATs and repeat as needed. Alternately, Release() might
4511 // detach and extract a successor, but then pass the residual list to the wakee.
4512 // The wakee would be responsible for reattaching and remerging before it
4513 // competed for the lock.
4514 //
4515 // Both "pop" and DMR are immune from ABA corruption -- there can be
4516 // multiple concurrent pushers, but only one popper or detacher.
4517 // This implementation pops from the head of the list. This is unfair,
4518 // but tends to provide excellent throughput as hot threads remain hot.
4519 // (We wake recently run threads first).
4520 //
4521 // All paths through muxRelease() will execute a CAS.
4522 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4523 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4524 // executed within the critical section are complete and globally visible before the
4525 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4526 void Thread::muxRelease(volatile intptr_t * Lock) {
4527 for (;;) {
4528 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4529 assert(w & LOCKBIT, "invariant");
4530 if (w == LOCKBIT) return;
4531 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4532 assert(List != NULL, "invariant");
4533 assert(List->OnList == intptr_t(Lock), "invariant");
4534 ParkEvent * const nxt = List->ListNext;
4535 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4536
4537 // The following CAS() releases the lock and pops the head element.
4538 // The CAS() also ratifies the previously fetched lock-word value.
4539 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4540 continue;
4541 }
4542 List->OnList = 0;
4543 OrderAccess::fence();
4544 List->unpark();
4545 return;
4546 }
4547 }
4548
4549
4550 void Threads::verify() {
4551 ALL_JAVA_THREADS(p) {
4552 p->verify();
4553 }
4554 VMThread* thread = VMThread::vm_thread();
4555 if (thread != NULL) thread->verify();
4556 }
--- EOF ---