1 /*
2 * Copyright (c) 1997, 2016, 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/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/codeCacheExtensions.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/referencePendingListLocker.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jvmtifiles/jvmtiEnv.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logConfiguration.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/universe.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/objArrayOop.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/symbol.hpp"
53 #include "oops/verifyOopClosure.hpp"
54 #include "prims/jvm_misc.hpp"
55 #include "prims/jvmtiExport.hpp"
56 #include "prims/jvmtiThreadState.hpp"
57 #include "prims/privilegedStack.hpp"
58 #include "runtime/arguments.hpp"
59 #include "runtime/atomic.inline.hpp"
60 #include "runtime/biasedLocking.hpp"
61 #include "runtime/commandLineFlagConstraintList.hpp"
62 #include "runtime/commandLineFlagRangeList.hpp"
63 #include "runtime/deoptimization.hpp"
64 #include "runtime/fprofiler.hpp"
65 #include "runtime/frame.inline.hpp"
66 #include "runtime/globals.hpp"
67 #include "runtime/init.hpp"
68 #include "runtime/interfaceSupport.hpp"
69 #include "runtime/java.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniPeriodicChecker.hpp"
72 #include "runtime/timerTrace.hpp"
73 #include "runtime/memprofiler.hpp"
74 #include "runtime/mutexLocker.hpp"
75 #include "runtime/objectMonitor.hpp"
76 #include "runtime/orderAccess.inline.hpp"
77 #include "runtime/osThread.hpp"
78 #include "runtime/safepoint.hpp"
79 #include "runtime/sharedRuntime.hpp"
80 #include "runtime/statSampler.hpp"
81 #include "runtime/stubRoutines.hpp"
82 #include "runtime/sweeper.hpp"
83 #include "runtime/task.hpp"
84 #include "runtime/thread.inline.hpp"
85 #include "runtime/threadCritical.hpp"
86 #include "runtime/vframe.hpp"
87 #include "runtime/vframeArray.hpp"
88 #include "runtime/vframe_hp.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "runtime/vm_operations.hpp"
91 #include "runtime/vm_version.hpp"
92 #include "services/attachListener.hpp"
93 #include "services/management.hpp"
94 #include "services/memTracker.hpp"
95 #include "services/threadService.hpp"
96 #include "trace/traceMacros.hpp"
97 #include "trace/tracing.hpp"
98 #include "utilities/defaultStream.hpp"
99 #include "utilities/dtrace.hpp"
100 #include "utilities/events.hpp"
101 #include "utilities/macros.hpp"
102 #include "utilities/preserveException.hpp"
103 #if INCLUDE_ALL_GCS
104 #include "gc/cms/concurrentMarkSweepThread.hpp"
105 #include "gc/g1/concurrentMarkThread.inline.hpp"
106 #include "gc/parallel/pcTasks.hpp"
107 #endif // INCLUDE_ALL_GCS
108 #if INCLUDE_JVMCI
109 #include "jvmci/jvmciCompiler.hpp"
110 #include "jvmci/jvmciRuntime.hpp"
111 #endif
112 #ifdef COMPILER1
113 #include "c1/c1_Compiler.hpp"
114 #endif
115 #ifdef COMPILER2
116 #include "opto/c2compiler.hpp"
117 #include "opto/idealGraphPrinter.hpp"
118 #endif
119 #if INCLUDE_RTM_OPT
120 #include "runtime/rtmLocking.hpp"
121 #endif
122
123 // Initialization after module runtime initialization
124 void universe_post_module_init(); // must happen after call_initPhase2
125
126 #ifdef DTRACE_ENABLED
127
128 // Only bother with this argument setup if dtrace is available
129
130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
132
133 #define DTRACE_THREAD_PROBE(probe, javathread) \
134 { \
135 ResourceMark rm(this); \
136 int len = 0; \
137 const char* name = (javathread)->get_thread_name(); \
138 len = strlen(name); \
139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
140 (char *) name, len, \
141 java_lang_Thread::thread_id((javathread)->threadObj()), \
142 (uintptr_t) (javathread)->osthread()->thread_id(), \
143 java_lang_Thread::is_daemon((javathread)->threadObj())); \
144 }
145
146 #else // ndef DTRACE_ENABLED
147
148 #define DTRACE_THREAD_PROBE(probe, javathread)
149
150 #endif // ndef DTRACE_ENABLED
151
152 #ifndef USE_LIBRARY_BASED_TLS_ONLY
153 // Current thread is maintained as a thread-local variable
154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
155 #endif
156
157 // Class hierarchy
158 // - Thread
159 // - VMThread
160 // - WatcherThread
161 // - ConcurrentMarkSweepThread
162 // - JavaThread
163 // - CompilerThread
164
165 // ======= Thread ========
166 // Support for forcing alignment of thread objects for biased locking
167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
168 if (UseBiasedLocking) {
169 const int alignment = markOopDesc::biased_lock_alignment;
170 size_t aligned_size = size + (alignment - sizeof(intptr_t));
171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
172 : AllocateHeap(aligned_size, flags, CURRENT_PC,
173 AllocFailStrategy::RETURN_NULL);
174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
177 "JavaThread alignment code overflowed allocated storage");
178 if (aligned_addr != real_malloc_addr) {
179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
180 p2i(real_malloc_addr),
181 p2i(aligned_addr));
182 }
183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
184 return aligned_addr;
185 } else {
186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
188 }
189 }
190
191 void Thread::operator delete(void* p) {
192 if (UseBiasedLocking) {
193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
194 FreeHeap(real_malloc_addr);
195 } else {
196 FreeHeap(p);
197 }
198 }
199
200
201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
202 // JavaThread
203
204
205 Thread::Thread() {
206 // stack and get_thread
207 set_stack_base(NULL);
208 set_stack_size(0);
209 set_self_raw_id(0);
210 set_lgrp_id(-1);
211 DEBUG_ONLY(clear_suspendible_thread();)
212
213 // allocated data structures
214 set_osthread(NULL);
215 set_resource_area(new (mtThread)ResourceArea());
216 DEBUG_ONLY(_current_resource_mark = NULL;)
217 set_handle_area(new (mtThread) HandleArea(NULL));
218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
219 set_active_handles(NULL);
220 set_free_handle_block(NULL);
221 set_last_handle_mark(NULL);
222
223 // This initial value ==> never claimed.
224 _oops_do_parity = 0;
225
226 // the handle mark links itself to last_handle_mark
227 new HandleMark(this);
228
229 // plain initialization
230 debug_only(_owned_locks = NULL;)
231 debug_only(_allow_allocation_count = 0;)
232 NOT_PRODUCT(_allow_safepoint_count = 0;)
233 NOT_PRODUCT(_skip_gcalot = false;)
234 _jvmti_env_iteration_count = 0;
235 set_allocated_bytes(0);
236 _vm_operation_started_count = 0;
237 _vm_operation_completed_count = 0;
238 _current_pending_monitor = NULL;
239 _current_pending_monitor_is_from_java = true;
240 _current_waiting_monitor = NULL;
241 _num_nested_signal = 0;
242 omFreeList = NULL;
243 omFreeCount = 0;
244 omFreeProvision = 32;
245 omInUseList = NULL;
246 omInUseCount = 0;
247
248 #ifdef ASSERT
249 _visited_for_critical_count = false;
250 #endif
251
252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
253 Monitor::_safepoint_check_sometimes);
254 _suspend_flags = 0;
255
256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
257 _hashStateX = os::random();
258 _hashStateY = 842502087;
259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
260 _hashStateW = 273326509;
261
262 _OnTrap = 0;
263 _schedctl = NULL;
264 _Stalled = 0;
265 _TypeTag = 0x2BAD;
266
267 // Many of the following fields are effectively final - immutable
268 // Note that nascent threads can't use the Native Monitor-Mutex
269 // construct until the _MutexEvent is initialized ...
270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
271 // we might instead use a stack of ParkEvents that we could provision on-demand.
272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
273 // and ::Release()
274 _ParkEvent = ParkEvent::Allocate(this);
275 _SleepEvent = ParkEvent::Allocate(this);
276 _MutexEvent = ParkEvent::Allocate(this);
277 _MuxEvent = ParkEvent::Allocate(this);
278
279 #ifdef CHECK_UNHANDLED_OOPS
280 if (CheckUnhandledOops) {
281 _unhandled_oops = new UnhandledOops(this);
282 }
283 #endif // CHECK_UNHANDLED_OOPS
284 #ifdef ASSERT
285 if (UseBiasedLocking) {
286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
287 assert(this == _real_malloc_address ||
288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
289 "bug in forced alignment of thread objects");
290 }
291 #endif // ASSERT
292 }
293
294 void Thread::initialize_thread_current() {
295 #ifndef USE_LIBRARY_BASED_TLS_ONLY
296 assert(_thr_current == NULL, "Thread::current already initialized");
297 _thr_current = this;
298 #endif
299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
300 ThreadLocalStorage::set_thread(this);
301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
302 }
303
304 void Thread::clear_thread_current() {
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 #ifndef USE_LIBRARY_BASED_TLS_ONLY
307 _thr_current = NULL;
308 #endif
309 ThreadLocalStorage::set_thread(NULL);
310 }
311
312 void Thread::record_stack_base_and_size() {
313 set_stack_base(os::current_stack_base());
314 set_stack_size(os::current_stack_size());
315 // CR 7190089: on Solaris, primordial thread's stack is adjusted
316 // in initialize_thread(). Without the adjustment, stack size is
317 // incorrect if stack is set to unlimited (ulimit -s unlimited).
318 // So far, only Solaris has real implementation of initialize_thread().
319 //
320 // set up any platform-specific state.
321 os::initialize_thread(this);
322
323 // Set stack limits after thread is initialized.
324 if (is_Java_thread()) {
325 ((JavaThread*) this)->set_stack_overflow_limit();
326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
327 }
328 #if INCLUDE_NMT
329 // record thread's native stack, stack grows downward
330 MemTracker::record_thread_stack(stack_end(), stack_size());
331 #endif // INCLUDE_NMT
332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
334 os::current_thread_id(), p2i(stack_base() - stack_size()),
335 p2i(stack_base()), stack_size()/1024);
336 }
337
338
339 Thread::~Thread() {
340 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
341 ObjectSynchronizer::omFlush(this);
342
343 EVENT_THREAD_DESTRUCT(this);
344
345 // stack_base can be NULL if the thread is never started or exited before
346 // record_stack_base_and_size called. Although, we would like to ensure
347 // that all started threads do call record_stack_base_and_size(), there is
348 // not proper way to enforce that.
349 #if INCLUDE_NMT
350 if (_stack_base != NULL) {
351 MemTracker::release_thread_stack(stack_end(), stack_size());
352 #ifdef ASSERT
353 set_stack_base(NULL);
354 #endif
355 }
356 #endif // INCLUDE_NMT
357
358 // deallocate data structures
359 delete resource_area();
360 // since the handle marks are using the handle area, we have to deallocated the root
361 // handle mark before deallocating the thread's handle area,
362 assert(last_handle_mark() != NULL, "check we have an element");
363 delete last_handle_mark();
364 assert(last_handle_mark() == NULL, "check we have reached the end");
365
366 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
367 // We NULL out the fields for good hygiene.
368 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
369 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
370 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
371 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
372
373 delete handle_area();
374 delete metadata_handles();
375
376 // osthread() can be NULL, if creation of thread failed.
377 if (osthread() != NULL) os::free_thread(osthread());
378
379 delete _SR_lock;
380
381 // clear Thread::current if thread is deleting itself.
382 // Needed to ensure JNI correctly detects non-attached threads.
383 if (this == Thread::current()) {
384 clear_thread_current();
385 }
386
387 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
388 }
389
390 // NOTE: dummy function for assertion purpose.
391 void Thread::run() {
392 ShouldNotReachHere();
393 }
394
395 #ifdef ASSERT
396 // Private method to check for dangling thread pointer
397 void check_for_dangling_thread_pointer(Thread *thread) {
398 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
399 "possibility of dangling Thread pointer");
400 }
401 #endif
402
403 ThreadPriority Thread::get_priority(const Thread* const thread) {
404 ThreadPriority priority;
405 // Can return an error!
406 (void)os::get_priority(thread, priority);
407 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
408 return priority;
409 }
410
411 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
412 debug_only(check_for_dangling_thread_pointer(thread);)
413 // Can return an error!
414 (void)os::set_priority(thread, priority);
415 }
416
417
418 void Thread::start(Thread* thread) {
419 // Start is different from resume in that its safety is guaranteed by context or
420 // being called from a Java method synchronized on the Thread object.
421 if (!DisableStartThread) {
422 if (thread->is_Java_thread()) {
423 // Initialize the thread state to RUNNABLE before starting this thread.
424 // Can not set it after the thread started because we do not know the
425 // exact thread state at that time. It could be in MONITOR_WAIT or
426 // in SLEEPING or some other state.
427 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
428 java_lang_Thread::RUNNABLE);
429 }
430 os::start_thread(thread);
431 }
432 }
433
434 // Enqueue a VM_Operation to do the job for us - sometime later
435 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
436 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
437 VMThread::execute(vm_stop);
438 }
439
440
441 // Check if an external suspend request has completed (or has been
442 // cancelled). Returns true if the thread is externally suspended and
443 // false otherwise.
444 //
445 // The bits parameter returns information about the code path through
446 // the routine. Useful for debugging:
447 //
448 // set in is_ext_suspend_completed():
449 // 0x00000001 - routine was entered
450 // 0x00000010 - routine return false at end
451 // 0x00000100 - thread exited (return false)
452 // 0x00000200 - suspend request cancelled (return false)
453 // 0x00000400 - thread suspended (return true)
454 // 0x00001000 - thread is in a suspend equivalent state (return true)
455 // 0x00002000 - thread is native and walkable (return true)
456 // 0x00004000 - thread is native_trans and walkable (needed retry)
457 //
458 // set in wait_for_ext_suspend_completion():
459 // 0x00010000 - routine was entered
460 // 0x00020000 - suspend request cancelled before loop (return false)
461 // 0x00040000 - thread suspended before loop (return true)
462 // 0x00080000 - suspend request cancelled in loop (return false)
463 // 0x00100000 - thread suspended in loop (return true)
464 // 0x00200000 - suspend not completed during retry loop (return false)
465
466 // Helper class for tracing suspend wait debug bits.
467 //
468 // 0x00000100 indicates that the target thread exited before it could
469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
470 // 0x00080000 each indicate a cancelled suspend request so they don't
471 // count as wait failures either.
472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
473
474 class TraceSuspendDebugBits : public StackObj {
475 private:
476 JavaThread * jt;
477 bool is_wait;
478 bool called_by_wait; // meaningful when !is_wait
479 uint32_t * bits;
480
481 public:
482 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
483 uint32_t *_bits) {
484 jt = _jt;
485 is_wait = _is_wait;
486 called_by_wait = _called_by_wait;
487 bits = _bits;
488 }
489
490 ~TraceSuspendDebugBits() {
491 if (!is_wait) {
492 #if 1
493 // By default, don't trace bits for is_ext_suspend_completed() calls.
494 // That trace is very chatty.
495 return;
496 #else
497 if (!called_by_wait) {
498 // If tracing for is_ext_suspend_completed() is enabled, then only
499 // trace calls to it from wait_for_ext_suspend_completion()
500 return;
501 }
502 #endif
503 }
504
505 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
506 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
507 MutexLocker ml(Threads_lock); // needed for get_thread_name()
508 ResourceMark rm;
509
510 tty->print_cr(
511 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
512 jt->get_thread_name(), *bits);
513
514 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
515 }
516 }
517 }
518 };
519 #undef DEBUG_FALSE_BITS
520
521
522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
523 uint32_t *bits) {
524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
525
526 bool did_trans_retry = false; // only do thread_in_native_trans retry once
527 bool do_trans_retry; // flag to force the retry
528
529 *bits |= 0x00000001;
530
531 do {
532 do_trans_retry = false;
533
534 if (is_exiting()) {
535 // Thread is in the process of exiting. This is always checked
536 // first to reduce the risk of dereferencing a freed JavaThread.
537 *bits |= 0x00000100;
538 return false;
539 }
540
541 if (!is_external_suspend()) {
542 // Suspend request is cancelled. This is always checked before
543 // is_ext_suspended() to reduce the risk of a rogue resume
544 // confusing the thread that made the suspend request.
545 *bits |= 0x00000200;
546 return false;
547 }
548
549 if (is_ext_suspended()) {
550 // thread is suspended
551 *bits |= 0x00000400;
552 return true;
553 }
554
555 // Now that we no longer do hard suspends of threads running
556 // native code, the target thread can be changing thread state
557 // while we are in this routine:
558 //
559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
560 //
561 // We save a copy of the thread state as observed at this moment
562 // and make our decision about suspend completeness based on the
563 // copy. This closes the race where the thread state is seen as
564 // _thread_in_native_trans in the if-thread_blocked check, but is
565 // seen as _thread_blocked in if-thread_in_native_trans check.
566 JavaThreadState save_state = thread_state();
567
568 if (save_state == _thread_blocked && is_suspend_equivalent()) {
569 // If the thread's state is _thread_blocked and this blocking
570 // condition is known to be equivalent to a suspend, then we can
571 // consider the thread to be externally suspended. This means that
572 // the code that sets _thread_blocked has been modified to do
573 // self-suspension if the blocking condition releases. We also
574 // used to check for CONDVAR_WAIT here, but that is now covered by
575 // the _thread_blocked with self-suspension check.
576 //
577 // Return true since we wouldn't be here unless there was still an
578 // external suspend request.
579 *bits |= 0x00001000;
580 return true;
581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
582 // Threads running native code will self-suspend on native==>VM/Java
583 // transitions. If its stack is walkable (should always be the case
584 // unless this function is called before the actual java_suspend()
585 // call), then the wait is done.
586 *bits |= 0x00002000;
587 return true;
588 } else if (!called_by_wait && !did_trans_retry &&
589 save_state == _thread_in_native_trans &&
590 frame_anchor()->walkable()) {
591 // The thread is transitioning from thread_in_native to another
592 // thread state. check_safepoint_and_suspend_for_native_trans()
593 // will force the thread to self-suspend. If it hasn't gotten
594 // there yet we may have caught the thread in-between the native
595 // code check above and the self-suspend. Lucky us. If we were
596 // called by wait_for_ext_suspend_completion(), then it
597 // will be doing the retries so we don't have to.
598 //
599 // Since we use the saved thread state in the if-statement above,
600 // there is a chance that the thread has already transitioned to
601 // _thread_blocked by the time we get here. In that case, we will
602 // make a single unnecessary pass through the logic below. This
603 // doesn't hurt anything since we still do the trans retry.
604
605 *bits |= 0x00004000;
606
607 // Once the thread leaves thread_in_native_trans for another
608 // thread state, we break out of this retry loop. We shouldn't
609 // need this flag to prevent us from getting back here, but
610 // sometimes paranoia is good.
611 did_trans_retry = true;
612
613 // We wait for the thread to transition to a more usable state.
614 for (int i = 1; i <= SuspendRetryCount; i++) {
615 // We used to do an "os::yield_all(i)" call here with the intention
616 // that yielding would increase on each retry. However, the parameter
617 // is ignored on Linux which means the yield didn't scale up. Waiting
618 // on the SR_lock below provides a much more predictable scale up for
619 // the delay. It also provides a simple/direct point to check for any
620 // safepoint requests from the VMThread
621
622 // temporarily drops SR_lock while doing wait with safepoint check
623 // (if we're a JavaThread - the WatcherThread can also call this)
624 // and increase delay with each retry
625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
626
627 // check the actual thread state instead of what we saved above
628 if (thread_state() != _thread_in_native_trans) {
629 // the thread has transitioned to another thread state so
630 // try all the checks (except this one) one more time.
631 do_trans_retry = true;
632 break;
633 }
634 } // end retry loop
635
636
637 }
638 } while (do_trans_retry);
639
640 *bits |= 0x00000010;
641 return false;
642 }
643
644 // Wait for an external suspend request to complete (or be cancelled).
645 // Returns true if the thread is externally suspended and false otherwise.
646 //
647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
648 uint32_t *bits) {
649 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
650 false /* !called_by_wait */, bits);
651
652 // local flag copies to minimize SR_lock hold time
653 bool is_suspended;
654 bool pending;
655 uint32_t reset_bits;
656
657 // set a marker so is_ext_suspend_completed() knows we are the caller
658 *bits |= 0x00010000;
659
660 // We use reset_bits to reinitialize the bits value at the top of
661 // each retry loop. This allows the caller to make use of any
662 // unused bits for their own marking purposes.
663 reset_bits = *bits;
664
665 {
666 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
667 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
668 delay, bits);
669 pending = is_external_suspend();
670 }
671 // must release SR_lock to allow suspension to complete
672
673 if (!pending) {
674 // A cancelled suspend request is the only false return from
675 // is_ext_suspend_completed() that keeps us from entering the
676 // retry loop.
677 *bits |= 0x00020000;
678 return false;
679 }
680
681 if (is_suspended) {
682 *bits |= 0x00040000;
683 return true;
684 }
685
686 for (int i = 1; i <= retries; i++) {
687 *bits = reset_bits; // reinit to only track last retry
688
689 // We used to do an "os::yield_all(i)" call here with the intention
690 // that yielding would increase on each retry. However, the parameter
691 // is ignored on Linux which means the yield didn't scale up. Waiting
692 // on the SR_lock below provides a much more predictable scale up for
693 // the delay. It also provides a simple/direct point to check for any
694 // safepoint requests from the VMThread
695
696 {
697 MutexLocker ml(SR_lock());
698 // wait with safepoint check (if we're a JavaThread - the WatcherThread
699 // can also call this) and increase delay with each retry
700 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
701
702 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
703 delay, bits);
704
705 // It is possible for the external suspend request to be cancelled
706 // (by a resume) before the actual suspend operation is completed.
707 // Refresh our local copy to see if we still need to wait.
708 pending = is_external_suspend();
709 }
710
711 if (!pending) {
712 // A cancelled suspend request is the only false return from
713 // is_ext_suspend_completed() that keeps us from staying in the
714 // retry loop.
715 *bits |= 0x00080000;
716 return false;
717 }
718
719 if (is_suspended) {
720 *bits |= 0x00100000;
721 return true;
722 }
723 } // end retry loop
724
725 // thread did not suspend after all our retries
726 *bits |= 0x00200000;
727 return false;
728 }
729
730 #ifndef PRODUCT
731 void JavaThread::record_jump(address target, address instr, const char* file,
732 int line) {
733
734 // This should not need to be atomic as the only way for simultaneous
735 // updates is via interrupts. Even then this should be rare or non-existent
736 // and we don't care that much anyway.
737
738 int index = _jmp_ring_index;
739 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
740 _jmp_ring[index]._target = (intptr_t) target;
741 _jmp_ring[index]._instruction = (intptr_t) instr;
742 _jmp_ring[index]._file = file;
743 _jmp_ring[index]._line = line;
744 }
745 #endif // PRODUCT
746
747 // Called by flat profiler
748 // Callers have already called wait_for_ext_suspend_completion
749 // The assertion for that is currently too complex to put here:
750 bool JavaThread::profile_last_Java_frame(frame* _fr) {
751 bool gotframe = false;
752 // self suspension saves needed state.
753 if (has_last_Java_frame() && _anchor.walkable()) {
754 *_fr = pd_last_frame();
755 gotframe = true;
756 }
757 return gotframe;
758 }
759
760 void Thread::interrupt(Thread* thread) {
761 debug_only(check_for_dangling_thread_pointer(thread);)
762 os::interrupt(thread);
763 }
764
765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 // Note: If clear_interrupted==false, this simply fetches and
768 // returns the value of the field osthread()->interrupted().
769 return os::is_interrupted(thread, clear_interrupted);
770 }
771
772
773 // GC Support
774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
775 jint thread_parity = _oops_do_parity;
776 if (thread_parity != strong_roots_parity) {
777 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
778 if (res == thread_parity) {
779 return true;
780 } else {
781 guarantee(res == strong_roots_parity, "Or else what?");
782 return false;
783 }
784 }
785 return false;
786 }
787
788 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
789 active_handles()->oops_do(f);
790 // Do oop for ThreadShadow
791 f->do_oop((oop*)&_pending_exception);
792 handle_area()->oops_do(f);
793 }
794
795 void Thread::nmethods_do(CodeBlobClosure* cf) {
796 // no nmethods in a generic thread...
797 }
798
799 void Thread::metadata_handles_do(void f(Metadata*)) {
800 // Only walk the Handles in Thread.
801 if (metadata_handles() != NULL) {
802 for (int i = 0; i< metadata_handles()->length(); i++) {
803 f(metadata_handles()->at(i));
804 }
805 }
806 }
807
808 void Thread::print_on(outputStream* st) const {
809 // get_priority assumes osthread initialized
810 if (osthread() != NULL) {
811 int os_prio;
812 if (os::get_native_priority(this, &os_prio) == OS_OK) {
813 st->print("os_prio=%d ", os_prio);
814 }
815 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
816 ext().print_on(st);
817 osthread()->print_on(st);
818 }
819 debug_only(if (WizardMode) print_owned_locks_on(st);)
820 }
821
822 // Thread::print_on_error() is called by fatal error handler. Don't use
823 // any lock or allocate memory.
824 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
825 if (is_VM_thread()) st->print("VMThread");
826 else if (is_Compiler_thread()) st->print("CompilerThread");
827 else if (is_Java_thread()) st->print("JavaThread");
828 else if (is_GC_task_thread()) st->print("GCTaskThread");
829 else if (is_Watcher_thread()) st->print("WatcherThread");
830 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
831 else st->print("Thread");
832
833 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
834 p2i(stack_end()), p2i(stack_base()));
835
836 if (osthread()) {
837 st->print(" [id=%d]", osthread()->thread_id());
838 }
839 }
840
841 #ifdef ASSERT
842 void Thread::print_owned_locks_on(outputStream* st) const {
843 Monitor *cur = _owned_locks;
844 if (cur == NULL) {
845 st->print(" (no locks) ");
846 } else {
847 st->print_cr(" Locks owned:");
848 while (cur) {
849 cur->print_on(st);
850 cur = cur->next();
851 }
852 }
853 }
854
855 static int ref_use_count = 0;
856
857 bool Thread::owns_locks_but_compiled_lock() const {
858 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
859 if (cur != Compile_lock) return true;
860 }
861 return false;
862 }
863
864
865 #endif
866
867 #ifndef PRODUCT
868
869 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
870 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
871 // no threads which allow_vm_block's are held
872 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
873 // Check if current thread is allowed to block at a safepoint
874 if (!(_allow_safepoint_count == 0)) {
875 fatal("Possible safepoint reached by thread that does not allow it");
876 }
877 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
878 fatal("LEAF method calling lock?");
879 }
880
881 #ifdef ASSERT
882 if (potential_vm_operation && is_Java_thread()
883 && !Universe::is_bootstrapping()) {
884 // Make sure we do not hold any locks that the VM thread also uses.
885 // This could potentially lead to deadlocks
886 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
887 // Threads_lock is special, since the safepoint synchronization will not start before this is
888 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
889 // since it is used to transfer control between JavaThreads and the VMThread
890 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
891 if ((cur->allow_vm_block() &&
892 cur != Threads_lock &&
893 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
894 cur != VMOperationRequest_lock &&
895 cur != VMOperationQueue_lock) ||
896 cur->rank() == Mutex::special) {
897 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
898 }
899 }
900 }
901
902 if (GCALotAtAllSafepoints) {
903 // We could enter a safepoint here and thus have a gc
904 InterfaceSupport::check_gc_alot();
905 }
906 #endif
907 }
908 #endif
909
910 bool Thread::is_in_stack(address adr) const {
911 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
912 address end = os::current_stack_pointer();
913 // Allow non Java threads to call this without stack_base
914 if (_stack_base == NULL) return true;
915 if (stack_base() >= adr && adr >= end) return true;
916
917 return false;
918 }
919
920 bool Thread::is_in_usable_stack(address adr) const {
921 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
922 size_t usable_stack_size = _stack_size - stack_guard_size;
923
924 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
925 }
926
927
928 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
929 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
930 // used for compilation in the future. If that change is made, the need for these methods
931 // should be revisited, and they should be removed if possible.
932
933 bool Thread::is_lock_owned(address adr) const {
934 return on_local_stack(adr);
935 }
936
937 bool Thread::set_as_starting_thread() {
938 // NOTE: this must be called inside the main thread.
939 return os::create_main_thread((JavaThread*)this);
940 }
941
942 static void initialize_class(Symbol* class_name, TRAPS) {
943 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
944 InstanceKlass::cast(klass)->initialize(CHECK);
945 }
946
947
948 // Creates the initial ThreadGroup
949 static Handle create_initial_thread_group(TRAPS) {
950 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
951 instanceKlassHandle klass (THREAD, k);
952
953 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
954 {
955 JavaValue result(T_VOID);
956 JavaCalls::call_special(&result,
957 system_instance,
958 klass,
959 vmSymbols::object_initializer_name(),
960 vmSymbols::void_method_signature(),
961 CHECK_NH);
962 }
963 Universe::set_system_thread_group(system_instance());
964
965 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
966 {
967 JavaValue result(T_VOID);
968 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
969 JavaCalls::call_special(&result,
970 main_instance,
971 klass,
972 vmSymbols::object_initializer_name(),
973 vmSymbols::threadgroup_string_void_signature(),
974 system_instance,
975 string,
976 CHECK_NH);
977 }
978 return main_instance;
979 }
980
981 // Creates the initial Thread
982 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
983 TRAPS) {
984 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
985 instanceKlassHandle klass (THREAD, k);
986 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
987
988 java_lang_Thread::set_thread(thread_oop(), thread);
989 java_lang_Thread::set_priority(thread_oop(), NormPriority);
990 thread->set_threadObj(thread_oop());
991
992 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
993
994 JavaValue result(T_VOID);
995 JavaCalls::call_special(&result, thread_oop,
996 klass,
997 vmSymbols::object_initializer_name(),
998 vmSymbols::threadgroup_string_void_signature(),
999 thread_group,
1000 string,
1001 CHECK_NULL);
1002 os::set_native_thread_name("main");
1003 return thread_oop();
1004 }
1005
1006 char java_runtime_name[128] = "";
1007 char java_runtime_version[128] = "";
1008
1009 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1010 static const char* get_java_runtime_name(TRAPS) {
1011 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1012 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1013 fieldDescriptor fd;
1014 bool found = k != NULL &&
1015 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1016 vmSymbols::string_signature(), &fd);
1017 if (found) {
1018 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1019 if (name_oop == NULL) {
1020 return NULL;
1021 }
1022 const char* name = java_lang_String::as_utf8_string(name_oop,
1023 java_runtime_name,
1024 sizeof(java_runtime_name));
1025 return name;
1026 } else {
1027 return NULL;
1028 }
1029 }
1030
1031 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1032 static const char* get_java_runtime_version(TRAPS) {
1033 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1034 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1035 fieldDescriptor fd;
1036 bool found = k != NULL &&
1037 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1038 vmSymbols::string_signature(), &fd);
1039 if (found) {
1040 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1041 if (name_oop == NULL) {
1042 return NULL;
1043 }
1044 const char* name = java_lang_String::as_utf8_string(name_oop,
1045 java_runtime_version,
1046 sizeof(java_runtime_version));
1047 return name;
1048 } else {
1049 return NULL;
1050 }
1051 }
1052
1053 // General purpose hook into Java code, run once when the VM is initialized.
1054 // The Java library method itself may be changed independently from the VM.
1055 static void call_postVMInitHook(TRAPS) {
1056 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1057 instanceKlassHandle klass (THREAD, k);
1058 if (klass.not_null()) {
1059 JavaValue result(T_VOID);
1060 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1061 vmSymbols::void_method_signature(),
1062 CHECK);
1063 }
1064 }
1065
1066 static void reset_vm_info_property(TRAPS) {
1067 // the vm info string
1068 ResourceMark rm(THREAD);
1069 const char *vm_info = VM_Version::vm_info_string();
1070
1071 // java.lang.System class
1072 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1073 instanceKlassHandle klass (THREAD, k);
1074
1075 // setProperty arguments
1076 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1077 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1078
1079 // return value
1080 JavaValue r(T_OBJECT);
1081
1082 // public static String setProperty(String key, String value);
1083 JavaCalls::call_static(&r,
1084 klass,
1085 vmSymbols::setProperty_name(),
1086 vmSymbols::string_string_string_signature(),
1087 key_str,
1088 value_str,
1089 CHECK);
1090 }
1091
1092
1093 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1094 bool daemon, TRAPS) {
1095 assert(thread_group.not_null(), "thread group should be specified");
1096 assert(threadObj() == NULL, "should only create Java thread object once");
1097
1098 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1099 instanceKlassHandle klass (THREAD, k);
1100 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1101
1102 java_lang_Thread::set_thread(thread_oop(), this);
1103 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1104 set_threadObj(thread_oop());
1105
1106 JavaValue result(T_VOID);
1107 if (thread_name != NULL) {
1108 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1109 // Thread gets assigned specified name and null target
1110 JavaCalls::call_special(&result,
1111 thread_oop,
1112 klass,
1113 vmSymbols::object_initializer_name(),
1114 vmSymbols::threadgroup_string_void_signature(),
1115 thread_group, // Argument 1
1116 name, // Argument 2
1117 THREAD);
1118 } else {
1119 // Thread gets assigned name "Thread-nnn" and null target
1120 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1121 JavaCalls::call_special(&result,
1122 thread_oop,
1123 klass,
1124 vmSymbols::object_initializer_name(),
1125 vmSymbols::threadgroup_runnable_void_signature(),
1126 thread_group, // Argument 1
1127 Handle(), // Argument 2
1128 THREAD);
1129 }
1130
1131
1132 if (daemon) {
1133 java_lang_Thread::set_daemon(thread_oop());
1134 }
1135
1136 if (HAS_PENDING_EXCEPTION) {
1137 return;
1138 }
1139
1140 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1141 Handle threadObj(THREAD, this->threadObj());
1142
1143 JavaCalls::call_special(&result,
1144 thread_group,
1145 group,
1146 vmSymbols::add_method_name(),
1147 vmSymbols::thread_void_signature(),
1148 threadObj, // Arg 1
1149 THREAD);
1150 }
1151
1152 // NamedThread -- non-JavaThread subclasses with multiple
1153 // uniquely named instances should derive from this.
1154 NamedThread::NamedThread() : Thread() {
1155 _name = NULL;
1156 _processed_thread = NULL;
1157 _gc_id = GCId::undefined();
1158 }
1159
1160 NamedThread::~NamedThread() {
1161 if (_name != NULL) {
1162 FREE_C_HEAP_ARRAY(char, _name);
1163 _name = NULL;
1164 }
1165 }
1166
1167 void NamedThread::set_name(const char* format, ...) {
1168 guarantee(_name == NULL, "Only get to set name once.");
1169 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1170 guarantee(_name != NULL, "alloc failure");
1171 va_list ap;
1172 va_start(ap, format);
1173 jio_vsnprintf(_name, max_name_len, format, ap);
1174 va_end(ap);
1175 }
1176
1177 void NamedThread::initialize_named_thread() {
1178 set_native_thread_name(name());
1179 }
1180
1181 void NamedThread::print_on(outputStream* st) const {
1182 st->print("\"%s\" ", name());
1183 Thread::print_on(st);
1184 st->cr();
1185 }
1186
1187
1188 // ======= WatcherThread ========
1189
1190 // The watcher thread exists to simulate timer interrupts. It should
1191 // be replaced by an abstraction over whatever native support for
1192 // timer interrupts exists on the platform.
1193
1194 WatcherThread* WatcherThread::_watcher_thread = NULL;
1195 bool WatcherThread::_startable = false;
1196 volatile bool WatcherThread::_should_terminate = false;
1197
1198 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1199 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1200 if (os::create_thread(this, os::watcher_thread)) {
1201 _watcher_thread = this;
1202
1203 // Set the watcher thread to the highest OS priority which should not be
1204 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1205 // is created. The only normal thread using this priority is the reference
1206 // handler thread, which runs for very short intervals only.
1207 // If the VMThread's priority is not lower than the WatcherThread profiling
1208 // will be inaccurate.
1209 os::set_priority(this, MaxPriority);
1210 if (!DisableStartThread) {
1211 os::start_thread(this);
1212 }
1213 }
1214 }
1215
1216 int WatcherThread::sleep() const {
1217 // The WatcherThread does not participate in the safepoint protocol
1218 // for the PeriodicTask_lock because it is not a JavaThread.
1219 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1220
1221 if (_should_terminate) {
1222 // check for termination before we do any housekeeping or wait
1223 return 0; // we did not sleep.
1224 }
1225
1226 // remaining will be zero if there are no tasks,
1227 // causing the WatcherThread to sleep until a task is
1228 // enrolled
1229 int remaining = PeriodicTask::time_to_wait();
1230 int time_slept = 0;
1231
1232 // we expect this to timeout - we only ever get unparked when
1233 // we should terminate or when a new task has been enrolled
1234 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1235
1236 jlong time_before_loop = os::javaTimeNanos();
1237
1238 while (true) {
1239 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1240 remaining);
1241 jlong now = os::javaTimeNanos();
1242
1243 if (remaining == 0) {
1244 // if we didn't have any tasks we could have waited for a long time
1245 // consider the time_slept zero and reset time_before_loop
1246 time_slept = 0;
1247 time_before_loop = now;
1248 } else {
1249 // need to recalculate since we might have new tasks in _tasks
1250 time_slept = (int) ((now - time_before_loop) / 1000000);
1251 }
1252
1253 // Change to task list or spurious wakeup of some kind
1254 if (timedout || _should_terminate) {
1255 break;
1256 }
1257
1258 remaining = PeriodicTask::time_to_wait();
1259 if (remaining == 0) {
1260 // Last task was just disenrolled so loop around and wait until
1261 // another task gets enrolled
1262 continue;
1263 }
1264
1265 remaining -= time_slept;
1266 if (remaining <= 0) {
1267 break;
1268 }
1269 }
1270
1271 return time_slept;
1272 }
1273
1274 void WatcherThread::run() {
1275 assert(this == watcher_thread(), "just checking");
1276
1277 this->record_stack_base_and_size();
1278 this->set_native_thread_name(this->name());
1279 this->set_active_handles(JNIHandleBlock::allocate_block());
1280 while (true) {
1281 assert(watcher_thread() == Thread::current(), "thread consistency check");
1282 assert(watcher_thread() == this, "thread consistency check");
1283
1284 // Calculate how long it'll be until the next PeriodicTask work
1285 // should be done, and sleep that amount of time.
1286 int time_waited = sleep();
1287
1288 if (is_error_reported()) {
1289 // A fatal error has happened, the error handler(VMError::report_and_die)
1290 // should abort JVM after creating an error log file. However in some
1291 // rare cases, the error handler itself might deadlock. Here we try to
1292 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1293 //
1294 // This code is in WatcherThread because WatcherThread wakes up
1295 // periodically so the fatal error handler doesn't need to do anything;
1296 // also because the WatcherThread is less likely to crash than other
1297 // threads.
1298
1299 for (;;) {
1300 if (!ShowMessageBoxOnError
1301 && (OnError == NULL || OnError[0] == '\0')
1302 && Arguments::abort_hook() == NULL) {
1303 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1304 fdStream err(defaultStream::output_fd());
1305 err.print_raw_cr("# [ timer expired, abort... ]");
1306 // skip atexit/vm_exit/vm_abort hooks
1307 os::die();
1308 }
1309
1310 // Wake up 5 seconds later, the fatal handler may reset OnError or
1311 // ShowMessageBoxOnError when it is ready to abort.
1312 os::sleep(this, 5 * 1000, false);
1313 }
1314 }
1315
1316 if (_should_terminate) {
1317 // check for termination before posting the next tick
1318 break;
1319 }
1320
1321 PeriodicTask::real_time_tick(time_waited);
1322 }
1323
1324 // Signal that it is terminated
1325 {
1326 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1327 _watcher_thread = NULL;
1328 Terminator_lock->notify();
1329 }
1330 }
1331
1332 void WatcherThread::start() {
1333 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1334
1335 if (watcher_thread() == NULL && _startable) {
1336 _should_terminate = false;
1337 // Create the single instance of WatcherThread
1338 new WatcherThread();
1339 }
1340 }
1341
1342 void WatcherThread::make_startable() {
1343 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1344 _startable = true;
1345 }
1346
1347 void WatcherThread::stop() {
1348 {
1349 // Follow normal safepoint aware lock enter protocol since the
1350 // WatcherThread is stopped by another JavaThread.
1351 MutexLocker ml(PeriodicTask_lock);
1352 _should_terminate = true;
1353
1354 WatcherThread* watcher = watcher_thread();
1355 if (watcher != NULL) {
1356 // unpark the WatcherThread so it can see that it should terminate
1357 watcher->unpark();
1358 }
1359 }
1360
1361 MutexLocker mu(Terminator_lock);
1362
1363 while (watcher_thread() != NULL) {
1364 // This wait should make safepoint checks, wait without a timeout,
1365 // and wait as a suspend-equivalent condition.
1366 //
1367 // Note: If the FlatProfiler is running, then this thread is waiting
1368 // for the WatcherThread to terminate and the WatcherThread, via the
1369 // FlatProfiler task, is waiting for the external suspend request on
1370 // this thread to complete. wait_for_ext_suspend_completion() will
1371 // eventually timeout, but that takes time. Making this wait a
1372 // suspend-equivalent condition solves that timeout problem.
1373 //
1374 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1375 Mutex::_as_suspend_equivalent_flag);
1376 }
1377 }
1378
1379 void WatcherThread::unpark() {
1380 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1381 PeriodicTask_lock->notify();
1382 }
1383
1384 void WatcherThread::print_on(outputStream* st) const {
1385 st->print("\"%s\" ", name());
1386 Thread::print_on(st);
1387 st->cr();
1388 }
1389
1390 // ======= JavaThread ========
1391
1392 #if INCLUDE_JVMCI
1393
1394 jlong* JavaThread::_jvmci_old_thread_counters;
1395
1396 bool jvmci_counters_include(JavaThread* thread) {
1397 oop threadObj = thread->threadObj();
1398 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1399 }
1400
1401 void JavaThread::collect_counters(typeArrayOop array) {
1402 if (JVMCICounterSize > 0) {
1403 MutexLocker tl(Threads_lock);
1404 for (int i = 0; i < array->length(); i++) {
1405 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1406 }
1407 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1408 if (jvmci_counters_include(tp)) {
1409 for (int i = 0; i < array->length(); i++) {
1410 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1411 }
1412 }
1413 }
1414 }
1415 }
1416
1417 #endif // INCLUDE_JVMCI
1418
1419 // A JavaThread is a normal Java thread
1420
1421 void JavaThread::initialize() {
1422 // Initialize fields
1423
1424 set_saved_exception_pc(NULL);
1425 set_threadObj(NULL);
1426 _anchor.clear();
1427 set_entry_point(NULL);
1428 set_jni_functions(jni_functions());
1429 set_callee_target(NULL);
1430 set_vm_result(NULL);
1431 set_vm_result_2(NULL);
1432 set_vframe_array_head(NULL);
1433 set_vframe_array_last(NULL);
1434 set_deferred_locals(NULL);
1435 set_deopt_mark(NULL);
1436 set_deopt_nmethod(NULL);
1437 clear_must_deopt_id();
1438 set_monitor_chunks(NULL);
1439 set_next(NULL);
1440 set_thread_state(_thread_new);
1441 _terminated = _not_terminated;
1442 _privileged_stack_top = NULL;
1443 _array_for_gc = NULL;
1444 _suspend_equivalent = false;
1445 _in_deopt_handler = 0;
1446 _doing_unsafe_access = false;
1447 _stack_guard_state = stack_guard_unused;
1448 #if INCLUDE_JVMCI
1449 _pending_monitorenter = false;
1450 _pending_deoptimization = -1;
1451 _pending_failed_speculation = NULL;
1452 _pending_transfer_to_interpreter = false;
1453 _jvmci._alternate_call_target = NULL;
1454 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1455 if (JVMCICounterSize > 0) {
1456 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1457 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1458 } else {
1459 _jvmci_counters = NULL;
1460 }
1461 #endif // INCLUDE_JVMCI
1462 _reserved_stack_activation = NULL; // stack base not known yet
1463 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1464 _exception_pc = 0;
1465 _exception_handler_pc = 0;
1466 _is_method_handle_return = 0;
1467 _jvmti_thread_state= NULL;
1468 _should_post_on_exceptions_flag = JNI_FALSE;
1469 _jvmti_get_loaded_classes_closure = NULL;
1470 _interp_only_mode = 0;
1471 _special_runtime_exit_condition = _no_async_condition;
1472 _pending_async_exception = NULL;
1473 _thread_stat = NULL;
1474 _thread_stat = new ThreadStatistics();
1475 _blocked_on_compilation = false;
1476 _jni_active_critical = 0;
1477 _pending_jni_exception_check_fn = NULL;
1478 _do_not_unlock_if_synchronized = false;
1479 _cached_monitor_info = NULL;
1480 _parker = Parker::Allocate(this);
1481
1482 #ifndef PRODUCT
1483 _jmp_ring_index = 0;
1484 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1485 record_jump(NULL, NULL, NULL, 0);
1486 }
1487 #endif // PRODUCT
1488
1489 set_thread_profiler(NULL);
1490 if (FlatProfiler::is_active()) {
1491 // This is where we would decide to either give each thread it's own profiler
1492 // or use one global one from FlatProfiler,
1493 // or up to some count of the number of profiled threads, etc.
1494 ThreadProfiler* pp = new ThreadProfiler();
1495 pp->engage();
1496 set_thread_profiler(pp);
1497 }
1498
1499 // Setup safepoint state info for this thread
1500 ThreadSafepointState::create(this);
1501
1502 debug_only(_java_call_counter = 0);
1503
1504 // JVMTI PopFrame support
1505 _popframe_condition = popframe_inactive;
1506 _popframe_preserved_args = NULL;
1507 _popframe_preserved_args_size = 0;
1508 _frames_to_pop_failed_realloc = 0;
1509
1510 pd_initialize();
1511 }
1512
1513 #if INCLUDE_ALL_GCS
1514 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1515 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1516 #endif // INCLUDE_ALL_GCS
1517
1518 JavaThread::JavaThread(bool is_attaching_via_jni) :
1519 Thread()
1520 #if INCLUDE_ALL_GCS
1521 , _satb_mark_queue(&_satb_mark_queue_set),
1522 _dirty_card_queue(&_dirty_card_queue_set)
1523 #endif // INCLUDE_ALL_GCS
1524 {
1525 initialize();
1526 if (is_attaching_via_jni) {
1527 _jni_attach_state = _attaching_via_jni;
1528 } else {
1529 _jni_attach_state = _not_attaching_via_jni;
1530 }
1531 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1532 }
1533
1534 bool JavaThread::reguard_stack(address cur_sp) {
1535 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1536 && _stack_guard_state != stack_guard_reserved_disabled) {
1537 return true; // Stack already guarded or guard pages not needed.
1538 }
1539
1540 if (register_stack_overflow()) {
1541 // For those architectures which have separate register and
1542 // memory stacks, we must check the register stack to see if
1543 // it has overflowed.
1544 return false;
1545 }
1546
1547 // Java code never executes within the yellow zone: the latter is only
1548 // there to provoke an exception during stack banging. If java code
1549 // is executing there, either StackShadowPages should be larger, or
1550 // some exception code in c1, c2 or the interpreter isn't unwinding
1551 // when it should.
1552 guarantee(cur_sp > stack_reserved_zone_base(),
1553 "not enough space to reguard - increase StackShadowPages");
1554 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1555 enable_stack_yellow_reserved_zone();
1556 if (reserved_stack_activation() != stack_base()) {
1557 set_reserved_stack_activation(stack_base());
1558 }
1559 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1560 set_reserved_stack_activation(stack_base());
1561 enable_stack_reserved_zone();
1562 }
1563 return true;
1564 }
1565
1566 bool JavaThread::reguard_stack(void) {
1567 return reguard_stack(os::current_stack_pointer());
1568 }
1569
1570
1571 void JavaThread::block_if_vm_exited() {
1572 if (_terminated == _vm_exited) {
1573 // _vm_exited is set at safepoint, and Threads_lock is never released
1574 // we will block here forever
1575 Threads_lock->lock_without_safepoint_check();
1576 ShouldNotReachHere();
1577 }
1578 }
1579
1580
1581 // Remove this ifdef when C1 is ported to the compiler interface.
1582 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1583 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1584
1585 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1586 Thread()
1587 #if INCLUDE_ALL_GCS
1588 , _satb_mark_queue(&_satb_mark_queue_set),
1589 _dirty_card_queue(&_dirty_card_queue_set)
1590 #endif // INCLUDE_ALL_GCS
1591 {
1592 initialize();
1593 _jni_attach_state = _not_attaching_via_jni;
1594 set_entry_point(entry_point);
1595 // Create the native thread itself.
1596 // %note runtime_23
1597 os::ThreadType thr_type = os::java_thread;
1598 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1599 os::java_thread;
1600 os::create_thread(this, thr_type, stack_sz);
1601 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1602 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1603 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1604 // the exception consists of creating the exception object & initializing it, initialization
1605 // will leave the VM via a JavaCall and then all locks must be unlocked).
1606 //
1607 // The thread is still suspended when we reach here. Thread must be explicit started
1608 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1609 // by calling Threads:add. The reason why this is not done here, is because the thread
1610 // object must be fully initialized (take a look at JVM_Start)
1611 }
1612
1613 JavaThread::~JavaThread() {
1614
1615 // JSR166 -- return the parker to the free list
1616 Parker::Release(_parker);
1617 _parker = NULL;
1618
1619 // Free any remaining previous UnrollBlock
1620 vframeArray* old_array = vframe_array_last();
1621
1622 if (old_array != NULL) {
1623 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1624 old_array->set_unroll_block(NULL);
1625 delete old_info;
1626 delete old_array;
1627 }
1628
1629 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1630 if (deferred != NULL) {
1631 // This can only happen if thread is destroyed before deoptimization occurs.
1632 assert(deferred->length() != 0, "empty array!");
1633 do {
1634 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1635 deferred->remove_at(0);
1636 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1637 delete dlv;
1638 } while (deferred->length() != 0);
1639 delete deferred;
1640 }
1641
1642 // All Java related clean up happens in exit
1643 ThreadSafepointState::destroy(this);
1644 if (_thread_profiler != NULL) delete _thread_profiler;
1645 if (_thread_stat != NULL) delete _thread_stat;
1646
1647 #if INCLUDE_JVMCI
1648 if (JVMCICounterSize > 0) {
1649 if (jvmci_counters_include(this)) {
1650 for (int i = 0; i < JVMCICounterSize; i++) {
1651 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1652 }
1653 }
1654 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1655 }
1656 #endif // INCLUDE_JVMCI
1657 }
1658
1659
1660 // The first routine called by a new Java thread
1661 void JavaThread::run() {
1662 // initialize thread-local alloc buffer related fields
1663 this->initialize_tlab();
1664
1665 // used to test validity of stack trace backs
1666 this->record_base_of_stack_pointer();
1667
1668 // Record real stack base and size.
1669 this->record_stack_base_and_size();
1670
1671 this->create_stack_guard_pages();
1672
1673 this->cache_global_variables();
1674
1675 // Thread is now sufficient initialized to be handled by the safepoint code as being
1676 // in the VM. Change thread state from _thread_new to _thread_in_vm
1677 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1678
1679 assert(JavaThread::current() == this, "sanity check");
1680 assert(!Thread::current()->owns_locks(), "sanity check");
1681
1682 DTRACE_THREAD_PROBE(start, this);
1683
1684 // This operation might block. We call that after all safepoint checks for a new thread has
1685 // been completed.
1686 this->set_active_handles(JNIHandleBlock::allocate_block());
1687
1688 if (JvmtiExport::should_post_thread_life()) {
1689 JvmtiExport::post_thread_start(this);
1690 }
1691
1692 EventThreadStart event;
1693 if (event.should_commit()) {
1694 event.set_thread(THREAD_TRACE_ID(this));
1695 event.commit();
1696 }
1697
1698 // We call another function to do the rest so we are sure that the stack addresses used
1699 // from there will be lower than the stack base just computed
1700 thread_main_inner();
1701
1702 // Note, thread is no longer valid at this point!
1703 }
1704
1705
1706 void JavaThread::thread_main_inner() {
1707 assert(JavaThread::current() == this, "sanity check");
1708 assert(this->threadObj() != NULL, "just checking");
1709
1710 // Execute thread entry point unless this thread has a pending exception
1711 // or has been stopped before starting.
1712 // Note: Due to JVM_StopThread we can have pending exceptions already!
1713 if (!this->has_pending_exception() &&
1714 !java_lang_Thread::is_stillborn(this->threadObj())) {
1715 {
1716 ResourceMark rm(this);
1717 this->set_native_thread_name(this->get_thread_name());
1718 }
1719 HandleMark hm(this);
1720 this->entry_point()(this, this);
1721 }
1722
1723 DTRACE_THREAD_PROBE(stop, this);
1724
1725 this->exit(false);
1726 delete this;
1727 }
1728
1729
1730 static void ensure_join(JavaThread* thread) {
1731 // We do not need to grap the Threads_lock, since we are operating on ourself.
1732 Handle threadObj(thread, thread->threadObj());
1733 assert(threadObj.not_null(), "java thread object must exist");
1734 ObjectLocker lock(threadObj, thread);
1735 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1736 thread->clear_pending_exception();
1737 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1738 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1739 // Clear the native thread instance - this makes isAlive return false and allows the join()
1740 // to complete once we've done the notify_all below
1741 java_lang_Thread::set_thread(threadObj(), NULL);
1742 lock.notify_all(thread);
1743 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1744 thread->clear_pending_exception();
1745 }
1746
1747
1748 // For any new cleanup additions, please check to see if they need to be applied to
1749 // cleanup_failed_attach_current_thread as well.
1750 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1751 assert(this == JavaThread::current(), "thread consistency check");
1752
1753 HandleMark hm(this);
1754 Handle uncaught_exception(this, this->pending_exception());
1755 this->clear_pending_exception();
1756 Handle threadObj(this, this->threadObj());
1757 assert(threadObj.not_null(), "Java thread object should be created");
1758
1759 if (get_thread_profiler() != NULL) {
1760 get_thread_profiler()->disengage();
1761 ResourceMark rm;
1762 get_thread_profiler()->print(get_thread_name());
1763 }
1764
1765
1766 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1767 {
1768 EXCEPTION_MARK;
1769
1770 CLEAR_PENDING_EXCEPTION;
1771 }
1772 if (!destroy_vm) {
1773 if (uncaught_exception.not_null()) {
1774 EXCEPTION_MARK;
1775 // Call method Thread.dispatchUncaughtException().
1776 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1777 JavaValue result(T_VOID);
1778 JavaCalls::call_virtual(&result,
1779 threadObj, thread_klass,
1780 vmSymbols::dispatchUncaughtException_name(),
1781 vmSymbols::throwable_void_signature(),
1782 uncaught_exception,
1783 THREAD);
1784 if (HAS_PENDING_EXCEPTION) {
1785 ResourceMark rm(this);
1786 jio_fprintf(defaultStream::error_stream(),
1787 "\nException: %s thrown from the UncaughtExceptionHandler"
1788 " in thread \"%s\"\n",
1789 pending_exception()->klass()->external_name(),
1790 get_thread_name());
1791 CLEAR_PENDING_EXCEPTION;
1792 }
1793 }
1794
1795 // Called before the java thread exit since we want to read info
1796 // from java_lang_Thread object
1797 EventThreadEnd event;
1798 if (event.should_commit()) {
1799 event.set_thread(THREAD_TRACE_ID(this));
1800 event.commit();
1801 }
1802
1803 // Call after last event on thread
1804 EVENT_THREAD_EXIT(this);
1805
1806 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1807 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1808 // is deprecated anyhow.
1809 if (!is_Compiler_thread()) {
1810 int count = 3;
1811 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1812 EXCEPTION_MARK;
1813 JavaValue result(T_VOID);
1814 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1815 JavaCalls::call_virtual(&result,
1816 threadObj, thread_klass,
1817 vmSymbols::exit_method_name(),
1818 vmSymbols::void_method_signature(),
1819 THREAD);
1820 CLEAR_PENDING_EXCEPTION;
1821 }
1822 }
1823 // notify JVMTI
1824 if (JvmtiExport::should_post_thread_life()) {
1825 JvmtiExport::post_thread_end(this);
1826 }
1827
1828 // We have notified the agents that we are exiting, before we go on,
1829 // we must check for a pending external suspend request and honor it
1830 // in order to not surprise the thread that made the suspend request.
1831 while (true) {
1832 {
1833 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1834 if (!is_external_suspend()) {
1835 set_terminated(_thread_exiting);
1836 ThreadService::current_thread_exiting(this);
1837 break;
1838 }
1839 // Implied else:
1840 // Things get a little tricky here. We have a pending external
1841 // suspend request, but we are holding the SR_lock so we
1842 // can't just self-suspend. So we temporarily drop the lock
1843 // and then self-suspend.
1844 }
1845
1846 ThreadBlockInVM tbivm(this);
1847 java_suspend_self();
1848
1849 // We're done with this suspend request, but we have to loop around
1850 // and check again. Eventually we will get SR_lock without a pending
1851 // external suspend request and will be able to mark ourselves as
1852 // exiting.
1853 }
1854 // no more external suspends are allowed at this point
1855 } else {
1856 // before_exit() has already posted JVMTI THREAD_END events
1857 }
1858
1859 // Notify waiters on thread object. This has to be done after exit() is called
1860 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1861 // group should have the destroyed bit set before waiters are notified).
1862 ensure_join(this);
1863 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1864
1865 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1866 // held by this thread must be released. The spec does not distinguish
1867 // between JNI-acquired and regular Java monitors. We can only see
1868 // regular Java monitors here if monitor enter-exit matching is broken.
1869 //
1870 // Optionally release any monitors for regular JavaThread exits. This
1871 // is provided as a work around for any bugs in monitor enter-exit
1872 // matching. This can be expensive so it is not enabled by default.
1873 //
1874 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1875 // ObjectSynchronizer::release_monitors_owned_by_thread().
1876 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1877 // Sanity check even though JNI DetachCurrentThread() would have
1878 // returned JNI_ERR if there was a Java frame. JavaThread exit
1879 // should be done executing Java code by the time we get here.
1880 assert(!this->has_last_Java_frame(),
1881 "should not have a Java frame when detaching or exiting");
1882 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1883 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1884 }
1885
1886 // These things needs to be done while we are still a Java Thread. Make sure that thread
1887 // is in a consistent state, in case GC happens
1888 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1889
1890 if (active_handles() != NULL) {
1891 JNIHandleBlock* block = active_handles();
1892 set_active_handles(NULL);
1893 JNIHandleBlock::release_block(block);
1894 }
1895
1896 if (free_handle_block() != NULL) {
1897 JNIHandleBlock* block = free_handle_block();
1898 set_free_handle_block(NULL);
1899 JNIHandleBlock::release_block(block);
1900 }
1901
1902 // These have to be removed while this is still a valid thread.
1903 remove_stack_guard_pages();
1904
1905 if (UseTLAB) {
1906 tlab().make_parsable(true); // retire TLAB
1907 }
1908
1909 if (JvmtiEnv::environments_might_exist()) {
1910 JvmtiExport::cleanup_thread(this);
1911 }
1912
1913 // We must flush any deferred card marks before removing a thread from
1914 // the list of active threads.
1915 Universe::heap()->flush_deferred_store_barrier(this);
1916 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1917
1918 #if INCLUDE_ALL_GCS
1919 // We must flush the G1-related buffers before removing a thread
1920 // from the list of active threads. We must do this after any deferred
1921 // card marks have been flushed (above) so that any entries that are
1922 // added to the thread's dirty card queue as a result are not lost.
1923 if (UseG1GC) {
1924 flush_barrier_queues();
1925 }
1926 #endif // INCLUDE_ALL_GCS
1927
1928 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1929 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1930 os::current_thread_id());
1931
1932 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1933 Threads::remove(this);
1934 }
1935
1936 #if INCLUDE_ALL_GCS
1937 // Flush G1-related queues.
1938 void JavaThread::flush_barrier_queues() {
1939 satb_mark_queue().flush();
1940 dirty_card_queue().flush();
1941 }
1942
1943 void JavaThread::initialize_queues() {
1944 assert(!SafepointSynchronize::is_at_safepoint(),
1945 "we should not be at a safepoint");
1946
1947 SATBMarkQueue& satb_queue = satb_mark_queue();
1948 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1949 // The SATB queue should have been constructed with its active
1950 // field set to false.
1951 assert(!satb_queue.is_active(), "SATB queue should not be active");
1952 assert(satb_queue.is_empty(), "SATB queue should be empty");
1953 // If we are creating the thread during a marking cycle, we should
1954 // set the active field of the SATB queue to true.
1955 if (satb_queue_set.is_active()) {
1956 satb_queue.set_active(true);
1957 }
1958
1959 DirtyCardQueue& dirty_queue = dirty_card_queue();
1960 // The dirty card queue should have been constructed with its
1961 // active field set to true.
1962 assert(dirty_queue.is_active(), "dirty card queue should be active");
1963 }
1964 #endif // INCLUDE_ALL_GCS
1965
1966 void JavaThread::cleanup_failed_attach_current_thread() {
1967 if (get_thread_profiler() != NULL) {
1968 get_thread_profiler()->disengage();
1969 ResourceMark rm;
1970 get_thread_profiler()->print(get_thread_name());
1971 }
1972
1973 if (active_handles() != NULL) {
1974 JNIHandleBlock* block = active_handles();
1975 set_active_handles(NULL);
1976 JNIHandleBlock::release_block(block);
1977 }
1978
1979 if (free_handle_block() != NULL) {
1980 JNIHandleBlock* block = free_handle_block();
1981 set_free_handle_block(NULL);
1982 JNIHandleBlock::release_block(block);
1983 }
1984
1985 // These have to be removed while this is still a valid thread.
1986 remove_stack_guard_pages();
1987
1988 if (UseTLAB) {
1989 tlab().make_parsable(true); // retire TLAB, if any
1990 }
1991
1992 #if INCLUDE_ALL_GCS
1993 if (UseG1GC) {
1994 flush_barrier_queues();
1995 }
1996 #endif // INCLUDE_ALL_GCS
1997
1998 Threads::remove(this);
1999 delete this;
2000 }
2001
2002
2003
2004
2005 JavaThread* JavaThread::active() {
2006 Thread* thread = Thread::current();
2007 if (thread->is_Java_thread()) {
2008 return (JavaThread*) thread;
2009 } else {
2010 assert(thread->is_VM_thread(), "this must be a vm thread");
2011 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2012 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2013 assert(ret->is_Java_thread(), "must be a Java thread");
2014 return ret;
2015 }
2016 }
2017
2018 bool JavaThread::is_lock_owned(address adr) const {
2019 if (Thread::is_lock_owned(adr)) return true;
2020
2021 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2022 if (chunk->contains(adr)) return true;
2023 }
2024
2025 return false;
2026 }
2027
2028
2029 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2030 chunk->set_next(monitor_chunks());
2031 set_monitor_chunks(chunk);
2032 }
2033
2034 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2035 guarantee(monitor_chunks() != NULL, "must be non empty");
2036 if (monitor_chunks() == chunk) {
2037 set_monitor_chunks(chunk->next());
2038 } else {
2039 MonitorChunk* prev = monitor_chunks();
2040 while (prev->next() != chunk) prev = prev->next();
2041 prev->set_next(chunk->next());
2042 }
2043 }
2044
2045 // JVM support.
2046
2047 // Note: this function shouldn't block if it's called in
2048 // _thread_in_native_trans state (such as from
2049 // check_special_condition_for_native_trans()).
2050 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2051
2052 if (has_last_Java_frame() && has_async_condition()) {
2053 // If we are at a polling page safepoint (not a poll return)
2054 // then we must defer async exception because live registers
2055 // will be clobbered by the exception path. Poll return is
2056 // ok because the call we a returning from already collides
2057 // with exception handling registers and so there is no issue.
2058 // (The exception handling path kills call result registers but
2059 // this is ok since the exception kills the result anyway).
2060
2061 if (is_at_poll_safepoint()) {
2062 // if the code we are returning to has deoptimized we must defer
2063 // the exception otherwise live registers get clobbered on the
2064 // exception path before deoptimization is able to retrieve them.
2065 //
2066 RegisterMap map(this, false);
2067 frame caller_fr = last_frame().sender(&map);
2068 assert(caller_fr.is_compiled_frame(), "what?");
2069 if (caller_fr.is_deoptimized_frame()) {
2070 log_info(exceptions)("deferred async exception at compiled safepoint");
2071 return;
2072 }
2073 }
2074 }
2075
2076 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2077 if (condition == _no_async_condition) {
2078 // Conditions have changed since has_special_runtime_exit_condition()
2079 // was called:
2080 // - if we were here only because of an external suspend request,
2081 // then that was taken care of above (or cancelled) so we are done
2082 // - if we were here because of another async request, then it has
2083 // been cleared between the has_special_runtime_exit_condition()
2084 // and now so again we are done
2085 return;
2086 }
2087
2088 // Check for pending async. exception
2089 if (_pending_async_exception != NULL) {
2090 // Only overwrite an already pending exception, if it is not a threadDeath.
2091 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2092
2093 // We cannot call Exceptions::_throw(...) here because we cannot block
2094 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2095
2096 if (log_is_enabled(Info, exceptions)) {
2097 ResourceMark rm;
2098 outputStream* logstream = LogHandle(exceptions)::info_stream();
2099 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2100 if (has_last_Java_frame()) {
2101 frame f = last_frame();
2102 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2103 }
2104 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2105 }
2106 _pending_async_exception = NULL;
2107 clear_has_async_exception();
2108 }
2109 }
2110
2111 if (check_unsafe_error &&
2112 condition == _async_unsafe_access_error && !has_pending_exception()) {
2113 condition = _no_async_condition; // done
2114 switch (thread_state()) {
2115 case _thread_in_vm: {
2116 JavaThread* THREAD = this;
2117 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2118 }
2119 case _thread_in_native: {
2120 ThreadInVMfromNative tiv(this);
2121 JavaThread* THREAD = this;
2122 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2123 }
2124 case _thread_in_Java: {
2125 ThreadInVMfromJava tiv(this);
2126 JavaThread* THREAD = this;
2127 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2128 }
2129 default:
2130 ShouldNotReachHere();
2131 }
2132 }
2133
2134 assert(condition == _no_async_condition || has_pending_exception() ||
2135 (!check_unsafe_error && condition == _async_unsafe_access_error),
2136 "must have handled the async condition, if no exception");
2137 }
2138
2139 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2140 //
2141 // Check for pending external suspend. Internal suspend requests do
2142 // not use handle_special_runtime_exit_condition().
2143 // If JNIEnv proxies are allowed, don't self-suspend if the target
2144 // thread is not the current thread. In older versions of jdbx, jdbx
2145 // threads could call into the VM with another thread's JNIEnv so we
2146 // can be here operating on behalf of a suspended thread (4432884).
2147 bool do_self_suspend = is_external_suspend_with_lock();
2148 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2149 //
2150 // Because thread is external suspended the safepoint code will count
2151 // thread as at a safepoint. This can be odd because we can be here
2152 // as _thread_in_Java which would normally transition to _thread_blocked
2153 // at a safepoint. We would like to mark the thread as _thread_blocked
2154 // before calling java_suspend_self like all other callers of it but
2155 // we must then observe proper safepoint protocol. (We can't leave
2156 // _thread_blocked with a safepoint in progress). However we can be
2157 // here as _thread_in_native_trans so we can't use a normal transition
2158 // constructor/destructor pair because they assert on that type of
2159 // transition. We could do something like:
2160 //
2161 // JavaThreadState state = thread_state();
2162 // set_thread_state(_thread_in_vm);
2163 // {
2164 // ThreadBlockInVM tbivm(this);
2165 // java_suspend_self()
2166 // }
2167 // set_thread_state(_thread_in_vm_trans);
2168 // if (safepoint) block;
2169 // set_thread_state(state);
2170 //
2171 // but that is pretty messy. Instead we just go with the way the
2172 // code has worked before and note that this is the only path to
2173 // java_suspend_self that doesn't put the thread in _thread_blocked
2174 // mode.
2175
2176 frame_anchor()->make_walkable(this);
2177 java_suspend_self();
2178
2179 // We might be here for reasons in addition to the self-suspend request
2180 // so check for other async requests.
2181 }
2182
2183 if (check_asyncs) {
2184 check_and_handle_async_exceptions();
2185 }
2186 }
2187
2188 void JavaThread::send_thread_stop(oop java_throwable) {
2189 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2190 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2191 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2192
2193 // Do not throw asynchronous exceptions against the compiler thread
2194 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2195 if (!can_call_java()) return;
2196
2197 {
2198 // Actually throw the Throwable against the target Thread - however
2199 // only if there is no thread death exception installed already.
2200 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2201 // If the topmost frame is a runtime stub, then we are calling into
2202 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2203 // must deoptimize the caller before continuing, as the compiled exception handler table
2204 // may not be valid
2205 if (has_last_Java_frame()) {
2206 frame f = last_frame();
2207 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2208 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2209 RegisterMap reg_map(this, UseBiasedLocking);
2210 frame compiled_frame = f.sender(®_map);
2211 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2212 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2213 }
2214 }
2215 }
2216
2217 // Set async. pending exception in thread.
2218 set_pending_async_exception(java_throwable);
2219
2220 if (log_is_enabled(Info, exceptions)) {
2221 ResourceMark rm;
2222 log_info(exceptions)("Pending Async. exception installed of type: %s",
2223 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2224 }
2225 // for AbortVMOnException flag
2226 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2227 }
2228 }
2229
2230
2231 // Interrupt thread so it will wake up from a potential wait()
2232 Thread::interrupt(this);
2233 }
2234
2235 // External suspension mechanism.
2236 //
2237 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2238 // to any VM_locks and it is at a transition
2239 // Self-suspension will happen on the transition out of the vm.
2240 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2241 //
2242 // Guarantees on return:
2243 // + Target thread will not execute any new bytecode (that's why we need to
2244 // force a safepoint)
2245 // + Target thread will not enter any new monitors
2246 //
2247 void JavaThread::java_suspend() {
2248 { MutexLocker mu(Threads_lock);
2249 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2250 return;
2251 }
2252 }
2253
2254 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2255 if (!is_external_suspend()) {
2256 // a racing resume has cancelled us; bail out now
2257 return;
2258 }
2259
2260 // suspend is done
2261 uint32_t debug_bits = 0;
2262 // Warning: is_ext_suspend_completed() may temporarily drop the
2263 // SR_lock to allow the thread to reach a stable thread state if
2264 // it is currently in a transient thread state.
2265 if (is_ext_suspend_completed(false /* !called_by_wait */,
2266 SuspendRetryDelay, &debug_bits)) {
2267 return;
2268 }
2269 }
2270
2271 VM_ForceSafepoint vm_suspend;
2272 VMThread::execute(&vm_suspend);
2273 }
2274
2275 // Part II of external suspension.
2276 // A JavaThread self suspends when it detects a pending external suspend
2277 // request. This is usually on transitions. It is also done in places
2278 // where continuing to the next transition would surprise the caller,
2279 // e.g., monitor entry.
2280 //
2281 // Returns the number of times that the thread self-suspended.
2282 //
2283 // Note: DO NOT call java_suspend_self() when you just want to block current
2284 // thread. java_suspend_self() is the second stage of cooperative
2285 // suspension for external suspend requests and should only be used
2286 // to complete an external suspend request.
2287 //
2288 int JavaThread::java_suspend_self() {
2289 int ret = 0;
2290
2291 // we are in the process of exiting so don't suspend
2292 if (is_exiting()) {
2293 clear_external_suspend();
2294 return ret;
2295 }
2296
2297 assert(_anchor.walkable() ||
2298 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2299 "must have walkable stack");
2300
2301 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2302
2303 assert(!this->is_ext_suspended(),
2304 "a thread trying to self-suspend should not already be suspended");
2305
2306 if (this->is_suspend_equivalent()) {
2307 // If we are self-suspending as a result of the lifting of a
2308 // suspend equivalent condition, then the suspend_equivalent
2309 // flag is not cleared until we set the ext_suspended flag so
2310 // that wait_for_ext_suspend_completion() returns consistent
2311 // results.
2312 this->clear_suspend_equivalent();
2313 }
2314
2315 // A racing resume may have cancelled us before we grabbed SR_lock
2316 // above. Or another external suspend request could be waiting for us
2317 // by the time we return from SR_lock()->wait(). The thread
2318 // that requested the suspension may already be trying to walk our
2319 // stack and if we return now, we can change the stack out from under
2320 // it. This would be a "bad thing (TM)" and cause the stack walker
2321 // to crash. We stay self-suspended until there are no more pending
2322 // external suspend requests.
2323 while (is_external_suspend()) {
2324 ret++;
2325 this->set_ext_suspended();
2326
2327 // _ext_suspended flag is cleared by java_resume()
2328 while (is_ext_suspended()) {
2329 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2330 }
2331 }
2332
2333 return ret;
2334 }
2335
2336 #ifdef ASSERT
2337 // verify the JavaThread has not yet been published in the Threads::list, and
2338 // hence doesn't need protection from concurrent access at this stage
2339 void JavaThread::verify_not_published() {
2340 if (!Threads_lock->owned_by_self()) {
2341 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2342 assert(!Threads::includes(this),
2343 "java thread shouldn't have been published yet!");
2344 } else {
2345 assert(!Threads::includes(this),
2346 "java thread shouldn't have been published yet!");
2347 }
2348 }
2349 #endif
2350
2351 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2352 // progress or when _suspend_flags is non-zero.
2353 // Current thread needs to self-suspend if there is a suspend request and/or
2354 // block if a safepoint is in progress.
2355 // Async exception ISN'T checked.
2356 // Note only the ThreadInVMfromNative transition can call this function
2357 // directly and when thread state is _thread_in_native_trans
2358 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2359 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2360
2361 JavaThread *curJT = JavaThread::current();
2362 bool do_self_suspend = thread->is_external_suspend();
2363
2364 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2365
2366 // If JNIEnv proxies are allowed, don't self-suspend if the target
2367 // thread is not the current thread. In older versions of jdbx, jdbx
2368 // threads could call into the VM with another thread's JNIEnv so we
2369 // can be here operating on behalf of a suspended thread (4432884).
2370 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2371 JavaThreadState state = thread->thread_state();
2372
2373 // We mark this thread_blocked state as a suspend-equivalent so
2374 // that a caller to is_ext_suspend_completed() won't be confused.
2375 // The suspend-equivalent state is cleared by java_suspend_self().
2376 thread->set_suspend_equivalent();
2377
2378 // If the safepoint code sees the _thread_in_native_trans state, it will
2379 // wait until the thread changes to other thread state. There is no
2380 // guarantee on how soon we can obtain the SR_lock and complete the
2381 // self-suspend request. It would be a bad idea to let safepoint wait for
2382 // too long. Temporarily change the state to _thread_blocked to
2383 // let the VM thread know that this thread is ready for GC. The problem
2384 // of changing thread state is that safepoint could happen just after
2385 // java_suspend_self() returns after being resumed, and VM thread will
2386 // see the _thread_blocked state. We must check for safepoint
2387 // after restoring the state and make sure we won't leave while a safepoint
2388 // is in progress.
2389 thread->set_thread_state(_thread_blocked);
2390 thread->java_suspend_self();
2391 thread->set_thread_state(state);
2392 // Make sure new state is seen by VM thread
2393 if (os::is_MP()) {
2394 if (UseMembar) {
2395 // Force a fence between the write above and read below
2396 OrderAccess::fence();
2397 } else {
2398 // Must use this rather than serialization page in particular on Windows
2399 InterfaceSupport::serialize_memory(thread);
2400 }
2401 }
2402 }
2403
2404 if (SafepointSynchronize::do_call_back()) {
2405 // If we are safepointing, then block the caller which may not be
2406 // the same as the target thread (see above).
2407 SafepointSynchronize::block(curJT);
2408 }
2409
2410 if (thread->is_deopt_suspend()) {
2411 thread->clear_deopt_suspend();
2412 RegisterMap map(thread, false);
2413 frame f = thread->last_frame();
2414 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2415 f = f.sender(&map);
2416 }
2417 if (f.id() == thread->must_deopt_id()) {
2418 thread->clear_must_deopt_id();
2419 f.deoptimize(thread);
2420 } else {
2421 fatal("missed deoptimization!");
2422 }
2423 }
2424 }
2425
2426 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2427 // progress or when _suspend_flags is non-zero.
2428 // Current thread needs to self-suspend if there is a suspend request and/or
2429 // block if a safepoint is in progress.
2430 // Also check for pending async exception (not including unsafe access error).
2431 // Note only the native==>VM/Java barriers can call this function and when
2432 // thread state is _thread_in_native_trans.
2433 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2434 check_safepoint_and_suspend_for_native_trans(thread);
2435
2436 if (thread->has_async_exception()) {
2437 // We are in _thread_in_native_trans state, don't handle unsafe
2438 // access error since that may block.
2439 thread->check_and_handle_async_exceptions(false);
2440 }
2441 }
2442
2443 // This is a variant of the normal
2444 // check_special_condition_for_native_trans with slightly different
2445 // semantics for use by critical native wrappers. It does all the
2446 // normal checks but also performs the transition back into
2447 // thread_in_Java state. This is required so that critical natives
2448 // can potentially block and perform a GC if they are the last thread
2449 // exiting the GCLocker.
2450 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2451 check_special_condition_for_native_trans(thread);
2452
2453 // Finish the transition
2454 thread->set_thread_state(_thread_in_Java);
2455
2456 if (thread->do_critical_native_unlock()) {
2457 ThreadInVMfromJavaNoAsyncException tiv(thread);
2458 GCLocker::unlock_critical(thread);
2459 thread->clear_critical_native_unlock();
2460 }
2461 }
2462
2463 // We need to guarantee the Threads_lock here, since resumes are not
2464 // allowed during safepoint synchronization
2465 // Can only resume from an external suspension
2466 void JavaThread::java_resume() {
2467 assert_locked_or_safepoint(Threads_lock);
2468
2469 // Sanity check: thread is gone, has started exiting or the thread
2470 // was not externally suspended.
2471 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2472 return;
2473 }
2474
2475 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2476
2477 clear_external_suspend();
2478
2479 if (is_ext_suspended()) {
2480 clear_ext_suspended();
2481 SR_lock()->notify_all();
2482 }
2483 }
2484
2485 size_t JavaThread::_stack_red_zone_size = 0;
2486 size_t JavaThread::_stack_yellow_zone_size = 0;
2487 size_t JavaThread::_stack_reserved_zone_size = 0;
2488 size_t JavaThread::_stack_shadow_zone_size = 0;
2489
2490 void JavaThread::create_stack_guard_pages() {
2491 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2492 address low_addr = stack_end();
2493 size_t len = stack_guard_zone_size();
2494
2495 int allocate = os::allocate_stack_guard_pages();
2496 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2497
2498 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2499 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2500 return;
2501 }
2502
2503 if (os::guard_memory((char *) low_addr, len)) {
2504 _stack_guard_state = stack_guard_enabled;
2505 } else {
2506 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2507 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2508 if (os::uncommit_memory((char *) low_addr, len)) {
2509 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2510 }
2511 return;
2512 }
2513
2514 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2515 PTR_FORMAT "-" PTR_FORMAT ".",
2516 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2517
2518 }
2519
2520 void JavaThread::remove_stack_guard_pages() {
2521 assert(Thread::current() == this, "from different thread");
2522 if (_stack_guard_state == stack_guard_unused) return;
2523 address low_addr = stack_end();
2524 size_t len = stack_guard_zone_size();
2525
2526 if (os::allocate_stack_guard_pages()) {
2527 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2528 _stack_guard_state = stack_guard_unused;
2529 } else {
2530 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2531 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2532 return;
2533 }
2534 } else {
2535 if (_stack_guard_state == stack_guard_unused) return;
2536 if (os::unguard_memory((char *) low_addr, len)) {
2537 _stack_guard_state = stack_guard_unused;
2538 } else {
2539 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2540 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2541 return;
2542 }
2543 }
2544
2545 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2546 PTR_FORMAT "-" PTR_FORMAT ".",
2547 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2548
2549 }
2550
2551 void JavaThread::enable_stack_reserved_zone() {
2552 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2553 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2554
2555 // The base notation is from the stack's point of view, growing downward.
2556 // We need to adjust it to work correctly with guard_memory()
2557 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2558
2559 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2560 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2561
2562 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2563 _stack_guard_state = stack_guard_enabled;
2564 } else {
2565 warning("Attempt to guard stack reserved zone failed.");
2566 }
2567 enable_register_stack_guard();
2568 }
2569
2570 void JavaThread::disable_stack_reserved_zone() {
2571 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2572 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2573
2574 // Simply return if called for a thread that does not use guard pages.
2575 if (_stack_guard_state == stack_guard_unused) return;
2576
2577 // The base notation is from the stack's point of view, growing downward.
2578 // We need to adjust it to work correctly with guard_memory()
2579 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2580
2581 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2582 _stack_guard_state = stack_guard_reserved_disabled;
2583 } else {
2584 warning("Attempt to unguard stack reserved zone failed.");
2585 }
2586 disable_register_stack_guard();
2587 }
2588
2589 void JavaThread::enable_stack_yellow_reserved_zone() {
2590 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2591 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2592
2593 // The base notation is from the stacks point of view, growing downward.
2594 // We need to adjust it to work correctly with guard_memory()
2595 address base = stack_red_zone_base();
2596
2597 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2598 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2599
2600 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2601 _stack_guard_state = stack_guard_enabled;
2602 } else {
2603 warning("Attempt to guard stack yellow zone failed.");
2604 }
2605 enable_register_stack_guard();
2606 }
2607
2608 void JavaThread::disable_stack_yellow_reserved_zone() {
2609 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2610 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2611
2612 // Simply return if called for a thread that does not use guard pages.
2613 if (_stack_guard_state == stack_guard_unused) return;
2614
2615 // The base notation is from the stacks point of view, growing downward.
2616 // We need to adjust it to work correctly with guard_memory()
2617 address base = stack_red_zone_base();
2618
2619 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2620 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2621 } else {
2622 warning("Attempt to unguard stack yellow zone failed.");
2623 }
2624 disable_register_stack_guard();
2625 }
2626
2627 void JavaThread::enable_stack_red_zone() {
2628 // The base notation is from the stacks point of view, growing downward.
2629 // We need to adjust it to work correctly with guard_memory()
2630 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2631 address base = stack_red_zone_base() - stack_red_zone_size();
2632
2633 guarantee(base < stack_base(), "Error calculating stack red zone");
2634 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2635
2636 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2637 warning("Attempt to guard stack red zone failed.");
2638 }
2639 }
2640
2641 void JavaThread::disable_stack_red_zone() {
2642 // The base notation is from the stacks point of view, growing downward.
2643 // We need to adjust it to work correctly with guard_memory()
2644 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2645 address base = stack_red_zone_base() - stack_red_zone_size();
2646 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2647 warning("Attempt to unguard stack red zone failed.");
2648 }
2649 }
2650
2651 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2652 // ignore is there is no stack
2653 if (!has_last_Java_frame()) return;
2654 // traverse the stack frames. Starts from top frame.
2655 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2656 frame* fr = fst.current();
2657 f(fr, fst.register_map());
2658 }
2659 }
2660
2661
2662 #ifndef PRODUCT
2663 // Deoptimization
2664 // Function for testing deoptimization
2665 void JavaThread::deoptimize() {
2666 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2667 StackFrameStream fst(this, UseBiasedLocking);
2668 bool deopt = false; // Dump stack only if a deopt actually happens.
2669 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2670 // Iterate over all frames in the thread and deoptimize
2671 for (; !fst.is_done(); fst.next()) {
2672 if (fst.current()->can_be_deoptimized()) {
2673
2674 if (only_at) {
2675 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2676 // consists of comma or carriage return separated numbers so
2677 // search for the current bci in that string.
2678 address pc = fst.current()->pc();
2679 nmethod* nm = (nmethod*) fst.current()->cb();
2680 ScopeDesc* sd = nm->scope_desc_at(pc);
2681 char buffer[8];
2682 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2683 size_t len = strlen(buffer);
2684 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2685 while (found != NULL) {
2686 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2687 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2688 // Check that the bci found is bracketed by terminators.
2689 break;
2690 }
2691 found = strstr(found + 1, buffer);
2692 }
2693 if (!found) {
2694 continue;
2695 }
2696 }
2697
2698 if (DebugDeoptimization && !deopt) {
2699 deopt = true; // One-time only print before deopt
2700 tty->print_cr("[BEFORE Deoptimization]");
2701 trace_frames();
2702 trace_stack();
2703 }
2704 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2705 }
2706 }
2707
2708 if (DebugDeoptimization && deopt) {
2709 tty->print_cr("[AFTER Deoptimization]");
2710 trace_frames();
2711 }
2712 }
2713
2714
2715 // Make zombies
2716 void JavaThread::make_zombies() {
2717 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2718 if (fst.current()->can_be_deoptimized()) {
2719 // it is a Java nmethod
2720 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2721 nm->make_not_entrant();
2722 }
2723 }
2724 }
2725 #endif // PRODUCT
2726
2727
2728 void JavaThread::deoptimized_wrt_marked_nmethods() {
2729 if (!has_last_Java_frame()) return;
2730 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2731 StackFrameStream fst(this, UseBiasedLocking);
2732 for (; !fst.is_done(); fst.next()) {
2733 if (fst.current()->should_be_deoptimized()) {
2734 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2735 }
2736 }
2737 }
2738
2739
2740 // If the caller is a NamedThread, then remember, in the current scope,
2741 // the given JavaThread in its _processed_thread field.
2742 class RememberProcessedThread: public StackObj {
2743 NamedThread* _cur_thr;
2744 public:
2745 RememberProcessedThread(JavaThread* jthr) {
2746 Thread* thread = Thread::current();
2747 if (thread->is_Named_thread()) {
2748 _cur_thr = (NamedThread *)thread;
2749 _cur_thr->set_processed_thread(jthr);
2750 } else {
2751 _cur_thr = NULL;
2752 }
2753 }
2754
2755 ~RememberProcessedThread() {
2756 if (_cur_thr) {
2757 _cur_thr->set_processed_thread(NULL);
2758 }
2759 }
2760 };
2761
2762 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2763 // Verify that the deferred card marks have been flushed.
2764 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2765
2766 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2767 // since there may be more than one thread using each ThreadProfiler.
2768
2769 // Traverse the GCHandles
2770 Thread::oops_do(f, cld_f, cf);
2771
2772 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2773
2774 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2775 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2776
2777 if (has_last_Java_frame()) {
2778 // Record JavaThread to GC thread
2779 RememberProcessedThread rpt(this);
2780
2781 // Traverse the privileged stack
2782 if (_privileged_stack_top != NULL) {
2783 _privileged_stack_top->oops_do(f);
2784 }
2785
2786 // traverse the registered growable array
2787 if (_array_for_gc != NULL) {
2788 for (int index = 0; index < _array_for_gc->length(); index++) {
2789 f->do_oop(_array_for_gc->adr_at(index));
2790 }
2791 }
2792
2793 // Traverse the monitor chunks
2794 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2795 chunk->oops_do(f);
2796 }
2797
2798 // Traverse the execution stack
2799 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2800 fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2801 }
2802 }
2803
2804 // callee_target is never live across a gc point so NULL it here should
2805 // it still contain a methdOop.
2806
2807 set_callee_target(NULL);
2808
2809 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2810 // If we have deferred set_locals there might be oops waiting to be
2811 // written
2812 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2813 if (list != NULL) {
2814 for (int i = 0; i < list->length(); i++) {
2815 list->at(i)->oops_do(f);
2816 }
2817 }
2818
2819 // Traverse instance variables at the end since the GC may be moving things
2820 // around using this function
2821 f->do_oop((oop*) &_threadObj);
2822 f->do_oop((oop*) &_vm_result);
2823 f->do_oop((oop*) &_exception_oop);
2824 f->do_oop((oop*) &_pending_async_exception);
2825
2826 if (jvmti_thread_state() != NULL) {
2827 jvmti_thread_state()->oops_do(f);
2828 }
2829 }
2830
2831 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2832 Thread::nmethods_do(cf); // (super method is a no-op)
2833
2834 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2835 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2836
2837 if (has_last_Java_frame()) {
2838 // Traverse the execution stack
2839 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2840 fst.current()->nmethods_do(cf);
2841 }
2842 }
2843 }
2844
2845 void JavaThread::metadata_do(void f(Metadata*)) {
2846 if (has_last_Java_frame()) {
2847 // Traverse the execution stack to call f() on the methods in the stack
2848 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2849 fst.current()->metadata_do(f);
2850 }
2851 } else if (is_Compiler_thread()) {
2852 // need to walk ciMetadata in current compile tasks to keep alive.
2853 CompilerThread* ct = (CompilerThread*)this;
2854 if (ct->env() != NULL) {
2855 ct->env()->metadata_do(f);
2856 }
2857 if (ct->task() != NULL) {
2858 ct->task()->metadata_do(f);
2859 }
2860 }
2861 }
2862
2863 // Printing
2864 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2865 switch (_thread_state) {
2866 case _thread_uninitialized: return "_thread_uninitialized";
2867 case _thread_new: return "_thread_new";
2868 case _thread_new_trans: return "_thread_new_trans";
2869 case _thread_in_native: return "_thread_in_native";
2870 case _thread_in_native_trans: return "_thread_in_native_trans";
2871 case _thread_in_vm: return "_thread_in_vm";
2872 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2873 case _thread_in_Java: return "_thread_in_Java";
2874 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2875 case _thread_blocked: return "_thread_blocked";
2876 case _thread_blocked_trans: return "_thread_blocked_trans";
2877 default: return "unknown thread state";
2878 }
2879 }
2880
2881 #ifndef PRODUCT
2882 void JavaThread::print_thread_state_on(outputStream *st) const {
2883 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2884 };
2885 void JavaThread::print_thread_state() const {
2886 print_thread_state_on(tty);
2887 }
2888 #endif // PRODUCT
2889
2890 // Called by Threads::print() for VM_PrintThreads operation
2891 void JavaThread::print_on(outputStream *st) const {
2892 st->print("\"%s\" ", get_thread_name());
2893 oop thread_oop = threadObj();
2894 if (thread_oop != NULL) {
2895 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2896 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2897 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2898 }
2899 Thread::print_on(st);
2900 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2901 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2902 if (thread_oop != NULL) {
2903 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2904 }
2905 #ifndef PRODUCT
2906 print_thread_state_on(st);
2907 _safepoint_state->print_on(st);
2908 #endif // PRODUCT
2909 if (is_Compiler_thread()) {
2910 CompilerThread* ct = (CompilerThread*)this;
2911 if (ct->task() != NULL) {
2912 st->print(" Compiling: ");
2913 ct->task()->print(st, NULL, true, false);
2914 } else {
2915 st->print(" No compile task");
2916 }
2917 st->cr();
2918 }
2919 }
2920
2921 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2922 st->print("%s", get_thread_name_string(buf, buflen));
2923 }
2924
2925 // Called by fatal error handler. The difference between this and
2926 // JavaThread::print() is that we can't grab lock or allocate memory.
2927 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2928 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2929 oop thread_obj = threadObj();
2930 if (thread_obj != NULL) {
2931 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2932 }
2933 st->print(" [");
2934 st->print("%s", _get_thread_state_name(_thread_state));
2935 if (osthread()) {
2936 st->print(", id=%d", osthread()->thread_id());
2937 }
2938 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2939 p2i(stack_end()), p2i(stack_base()));
2940 st->print("]");
2941 return;
2942 }
2943
2944 // Verification
2945
2946 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2947
2948 void JavaThread::verify() {
2949 // Verify oops in the thread.
2950 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2951
2952 // Verify the stack frames.
2953 frames_do(frame_verify);
2954 }
2955
2956 // CR 6300358 (sub-CR 2137150)
2957 // Most callers of this method assume that it can't return NULL but a
2958 // thread may not have a name whilst it is in the process of attaching to
2959 // the VM - see CR 6412693, and there are places where a JavaThread can be
2960 // seen prior to having it's threadObj set (eg JNI attaching threads and
2961 // if vm exit occurs during initialization). These cases can all be accounted
2962 // for such that this method never returns NULL.
2963 const char* JavaThread::get_thread_name() const {
2964 #ifdef ASSERT
2965 // early safepoints can hit while current thread does not yet have TLS
2966 if (!SafepointSynchronize::is_at_safepoint()) {
2967 Thread *cur = Thread::current();
2968 if (!(cur->is_Java_thread() && cur == this)) {
2969 // Current JavaThreads are allowed to get their own name without
2970 // the Threads_lock.
2971 assert_locked_or_safepoint(Threads_lock);
2972 }
2973 }
2974 #endif // ASSERT
2975 return get_thread_name_string();
2976 }
2977
2978 // Returns a non-NULL representation of this thread's name, or a suitable
2979 // descriptive string if there is no set name
2980 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2981 const char* name_str;
2982 oop thread_obj = threadObj();
2983 if (thread_obj != NULL) {
2984 oop name = java_lang_Thread::name(thread_obj);
2985 if (name != NULL) {
2986 if (buf == NULL) {
2987 name_str = java_lang_String::as_utf8_string(name);
2988 } else {
2989 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2990 }
2991 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2992 name_str = "<no-name - thread is attaching>";
2993 } else {
2994 name_str = Thread::name();
2995 }
2996 } else {
2997 name_str = Thread::name();
2998 }
2999 assert(name_str != NULL, "unexpected NULL thread name");
3000 return name_str;
3001 }
3002
3003
3004 const char* JavaThread::get_threadgroup_name() const {
3005 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3006 oop thread_obj = threadObj();
3007 if (thread_obj != NULL) {
3008 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3009 if (thread_group != NULL) {
3010 // ThreadGroup.name can be null
3011 return java_lang_ThreadGroup::name(thread_group);
3012 }
3013 }
3014 return NULL;
3015 }
3016
3017 const char* JavaThread::get_parent_name() const {
3018 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3019 oop thread_obj = threadObj();
3020 if (thread_obj != NULL) {
3021 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3022 if (thread_group != NULL) {
3023 oop parent = java_lang_ThreadGroup::parent(thread_group);
3024 if (parent != NULL) {
3025 // ThreadGroup.name can be null
3026 return java_lang_ThreadGroup::name(parent);
3027 }
3028 }
3029 }
3030 return NULL;
3031 }
3032
3033 ThreadPriority JavaThread::java_priority() const {
3034 oop thr_oop = threadObj();
3035 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3036 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3037 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3038 return priority;
3039 }
3040
3041 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3042
3043 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3044 // Link Java Thread object <-> C++ Thread
3045
3046 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3047 // and put it into a new Handle. The Handle "thread_oop" can then
3048 // be used to pass the C++ thread object to other methods.
3049
3050 // Set the Java level thread object (jthread) field of the
3051 // new thread (a JavaThread *) to C++ thread object using the
3052 // "thread_oop" handle.
3053
3054 // Set the thread field (a JavaThread *) of the
3055 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3056
3057 Handle thread_oop(Thread::current(),
3058 JNIHandles::resolve_non_null(jni_thread));
3059 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3060 "must be initialized");
3061 set_threadObj(thread_oop());
3062 java_lang_Thread::set_thread(thread_oop(), this);
3063
3064 if (prio == NoPriority) {
3065 prio = java_lang_Thread::priority(thread_oop());
3066 assert(prio != NoPriority, "A valid priority should be present");
3067 }
3068
3069 // Push the Java priority down to the native thread; needs Threads_lock
3070 Thread::set_priority(this, prio);
3071
3072 prepare_ext();
3073
3074 // Add the new thread to the Threads list and set it in motion.
3075 // We must have threads lock in order to call Threads::add.
3076 // It is crucial that we do not block before the thread is
3077 // added to the Threads list for if a GC happens, then the java_thread oop
3078 // will not be visited by GC.
3079 Threads::add(this);
3080 }
3081
3082 oop JavaThread::current_park_blocker() {
3083 // Support for JSR-166 locks
3084 oop thread_oop = threadObj();
3085 if (thread_oop != NULL &&
3086 JDK_Version::current().supports_thread_park_blocker()) {
3087 return java_lang_Thread::park_blocker(thread_oop);
3088 }
3089 return NULL;
3090 }
3091
3092
3093 void JavaThread::print_stack_on(outputStream* st) {
3094 if (!has_last_Java_frame()) return;
3095 ResourceMark rm;
3096 HandleMark hm;
3097
3098 RegisterMap reg_map(this);
3099 vframe* start_vf = last_java_vframe(®_map);
3100 int count = 0;
3101 for (vframe* f = start_vf; f; f = f->sender()) {
3102 if (f->is_java_frame()) {
3103 javaVFrame* jvf = javaVFrame::cast(f);
3104 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3105
3106 // Print out lock information
3107 if (JavaMonitorsInStackTrace) {
3108 jvf->print_lock_info_on(st, count);
3109 }
3110 } else {
3111 // Ignore non-Java frames
3112 }
3113
3114 // Bail-out case for too deep stacks
3115 count++;
3116 if (MaxJavaStackTraceDepth == count) return;
3117 }
3118 }
3119
3120
3121 // JVMTI PopFrame support
3122 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3123 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3124 if (in_bytes(size_in_bytes) != 0) {
3125 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3126 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3127 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3128 }
3129 }
3130
3131 void* JavaThread::popframe_preserved_args() {
3132 return _popframe_preserved_args;
3133 }
3134
3135 ByteSize JavaThread::popframe_preserved_args_size() {
3136 return in_ByteSize(_popframe_preserved_args_size);
3137 }
3138
3139 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3140 int sz = in_bytes(popframe_preserved_args_size());
3141 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3142 return in_WordSize(sz / wordSize);
3143 }
3144
3145 void JavaThread::popframe_free_preserved_args() {
3146 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3147 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3148 _popframe_preserved_args = NULL;
3149 _popframe_preserved_args_size = 0;
3150 }
3151
3152 #ifndef PRODUCT
3153
3154 void JavaThread::trace_frames() {
3155 tty->print_cr("[Describe stack]");
3156 int frame_no = 1;
3157 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3158 tty->print(" %d. ", frame_no++);
3159 fst.current()->print_value_on(tty, this);
3160 tty->cr();
3161 }
3162 }
3163
3164 class PrintAndVerifyOopClosure: public OopClosure {
3165 protected:
3166 template <class T> inline void do_oop_work(T* p) {
3167 oop obj = oopDesc::load_decode_heap_oop(p);
3168 if (obj == NULL) return;
3169 tty->print(INTPTR_FORMAT ": ", p2i(p));
3170 if (obj->is_oop_or_null()) {
3171 if (obj->is_objArray()) {
3172 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3173 } else {
3174 obj->print();
3175 }
3176 } else {
3177 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3178 }
3179 tty->cr();
3180 }
3181 public:
3182 virtual void do_oop(oop* p) { do_oop_work(p); }
3183 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3184 };
3185
3186
3187 static void oops_print(frame* f, const RegisterMap *map) {
3188 PrintAndVerifyOopClosure print;
3189 f->print_value();
3190 f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3191 }
3192
3193 // Print our all the locations that contain oops and whether they are
3194 // valid or not. This useful when trying to find the oldest frame
3195 // where an oop has gone bad since the frame walk is from youngest to
3196 // oldest.
3197 void JavaThread::trace_oops() {
3198 tty->print_cr("[Trace oops]");
3199 frames_do(oops_print);
3200 }
3201
3202
3203 #ifdef ASSERT
3204 // Print or validate the layout of stack frames
3205 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3206 ResourceMark rm;
3207 PRESERVE_EXCEPTION_MARK;
3208 FrameValues values;
3209 int frame_no = 0;
3210 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3211 fst.current()->describe(values, ++frame_no);
3212 if (depth == frame_no) break;
3213 }
3214 if (validate_only) {
3215 values.validate();
3216 } else {
3217 tty->print_cr("[Describe stack layout]");
3218 values.print(this);
3219 }
3220 }
3221 #endif
3222
3223 void JavaThread::trace_stack_from(vframe* start_vf) {
3224 ResourceMark rm;
3225 int vframe_no = 1;
3226 for (vframe* f = start_vf; f; f = f->sender()) {
3227 if (f->is_java_frame()) {
3228 javaVFrame::cast(f)->print_activation(vframe_no++);
3229 } else {
3230 f->print();
3231 }
3232 if (vframe_no > StackPrintLimit) {
3233 tty->print_cr("...<more frames>...");
3234 return;
3235 }
3236 }
3237 }
3238
3239
3240 void JavaThread::trace_stack() {
3241 if (!has_last_Java_frame()) return;
3242 ResourceMark rm;
3243 HandleMark hm;
3244 RegisterMap reg_map(this);
3245 trace_stack_from(last_java_vframe(®_map));
3246 }
3247
3248
3249 #endif // PRODUCT
3250
3251
3252 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3253 assert(reg_map != NULL, "a map must be given");
3254 frame f = last_frame();
3255 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3256 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3257 }
3258 return NULL;
3259 }
3260
3261
3262 Klass* JavaThread::security_get_caller_class(int depth) {
3263 vframeStream vfst(this);
3264 vfst.security_get_caller_frame(depth);
3265 if (!vfst.at_end()) {
3266 return vfst.method()->method_holder();
3267 }
3268 return NULL;
3269 }
3270
3271 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3272 assert(thread->is_Compiler_thread(), "must be compiler thread");
3273 CompileBroker::compiler_thread_loop();
3274 }
3275
3276 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3277 NMethodSweeper::sweeper_loop();
3278 }
3279
3280 // Create a CompilerThread
3281 CompilerThread::CompilerThread(CompileQueue* queue,
3282 CompilerCounters* counters)
3283 : JavaThread(&compiler_thread_entry) {
3284 _env = NULL;
3285 _log = NULL;
3286 _task = NULL;
3287 _queue = queue;
3288 _counters = counters;
3289 _buffer_blob = NULL;
3290 _compiler = NULL;
3291
3292 #ifndef PRODUCT
3293 _ideal_graph_printer = NULL;
3294 #endif
3295 }
3296
3297 bool CompilerThread::can_call_java() const {
3298 return _compiler != NULL && _compiler->is_jvmci();
3299 }
3300
3301 // Create sweeper thread
3302 CodeCacheSweeperThread::CodeCacheSweeperThread()
3303 : JavaThread(&sweeper_thread_entry) {
3304 _scanned_nmethod = NULL;
3305 }
3306 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3307 JavaThread::oops_do(f, cld_f, cf);
3308 if (_scanned_nmethod != NULL && cf != NULL) {
3309 // Safepoints can occur when the sweeper is scanning an nmethod so
3310 // process it here to make sure it isn't unloaded in the middle of
3311 // a scan.
3312 cf->do_code_blob(_scanned_nmethod);
3313 }
3314 }
3315
3316
3317 // ======= Threads ========
3318
3319 // The Threads class links together all active threads, and provides
3320 // operations over all threads. It is protected by its own Mutex
3321 // lock, which is also used in other contexts to protect thread
3322 // operations from having the thread being operated on from exiting
3323 // and going away unexpectedly (e.g., safepoint synchronization)
3324
3325 JavaThread* Threads::_thread_list = NULL;
3326 int Threads::_number_of_threads = 0;
3327 int Threads::_number_of_non_daemon_threads = 0;
3328 int Threads::_return_code = 0;
3329 int Threads::_thread_claim_parity = 0;
3330 size_t JavaThread::_stack_size_at_create = 0;
3331 #ifdef ASSERT
3332 bool Threads::_vm_complete = false;
3333 #endif
3334
3335 // All JavaThreads
3336 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3337
3338 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3339 void Threads::threads_do(ThreadClosure* tc) {
3340 assert_locked_or_safepoint(Threads_lock);
3341 // ALL_JAVA_THREADS iterates through all JavaThreads
3342 ALL_JAVA_THREADS(p) {
3343 tc->do_thread(p);
3344 }
3345 // Someday we could have a table or list of all non-JavaThreads.
3346 // For now, just manually iterate through them.
3347 tc->do_thread(VMThread::vm_thread());
3348 Universe::heap()->gc_threads_do(tc);
3349 WatcherThread *wt = WatcherThread::watcher_thread();
3350 // Strictly speaking, the following NULL check isn't sufficient to make sure
3351 // the data for WatcherThread is still valid upon being examined. However,
3352 // considering that WatchThread terminates when the VM is on the way to
3353 // exit at safepoint, the chance of the above is extremely small. The right
3354 // way to prevent termination of WatcherThread would be to acquire
3355 // Terminator_lock, but we can't do that without violating the lock rank
3356 // checking in some cases.
3357 if (wt != NULL) {
3358 tc->do_thread(wt);
3359 }
3360
3361 // If CompilerThreads ever become non-JavaThreads, add them here
3362 }
3363
3364 // The system initialization in the library has three phases.
3365 //
3366 // Phase 1: java.lang.System class initialization
3367 // java.lang.System is a primordial class loaded and initialized
3368 // by the VM early during startup. java.lang.System.<clinit>
3369 // only does registerNatives and keeps the rest of the class
3370 // initialization work later until thread initialization completes.
3371 //
3372 // System.initPhase1 initializes the system properties, the static
3373 // fields in, out, and err. Set up java signal handlers, OS-specific
3374 // system settings, and thread group of the main thread.
3375 static void call_initPhase1(TRAPS) {
3376 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3377 instanceKlassHandle klass (THREAD, k);
3378
3379 JavaValue result(T_VOID);
3380 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3381 vmSymbols::void_method_signature(), CHECK);
3382 }
3383
3384 // Phase 2. Module system initialization
3385 // This will initialize the module system. Only java.base classes
3386 // can be loaded until phase 2 completes.
3387 //
3388 // Call System.initPhase2 after the compiler initialization and jsr292
3389 // classes get initialized because module initialization runs a lot of java
3390 // code, that for performance reasons, should be compiled. Also, this will
3391 // enable the startup code to use lambda and other language features in this
3392 // phase and onward.
3393 //
3394 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3395 static void call_initPhase2(TRAPS) {
3396 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3397 instanceKlassHandle klass (THREAD, k);
3398
3399 JavaValue result(T_VOID);
3400 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3401 vmSymbols::void_method_signature(), CHECK);
3402 universe_post_module_init();
3403 }
3404
3405 // Phase 3. final setup - set security manager, system class loader and TCCL
3406 //
3407 // This will instantiate and set the security manager, set the system class
3408 // loader as well as the thread context class loader. The security manager
3409 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3410 // other modules or the application's classpath.
3411 static void call_initPhase3(TRAPS) {
3412 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3413 instanceKlassHandle klass (THREAD, k);
3414
3415 JavaValue result(T_VOID);
3416 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3417 vmSymbols::void_method_signature(), CHECK);
3418 }
3419
3420 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3421 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3422
3423 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3424 create_vm_init_libraries();
3425 }
3426
3427 initialize_class(vmSymbols::java_lang_String(), CHECK);
3428
3429 // Inject CompactStrings value after the static initializers for String ran.
3430 java_lang_String::set_compact_strings(CompactStrings);
3431
3432 // Initialize java_lang.System (needed before creating the thread)
3433 initialize_class(vmSymbols::java_lang_System(), CHECK);
3434 // The VM creates & returns objects of this class. Make sure it's initialized.
3435 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3436 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3437 Handle thread_group = create_initial_thread_group(CHECK);
3438 Universe::set_main_thread_group(thread_group());
3439 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3440 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3441 main_thread->set_threadObj(thread_object);
3442 // Set thread status to running since main thread has
3443 // been started and running.
3444 java_lang_Thread::set_thread_status(thread_object,
3445 java_lang_Thread::RUNNABLE);
3446
3447 // The VM creates objects of this class.
3448 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3449
3450 // The VM preresolves methods to these classes. Make sure that they get initialized
3451 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3452 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3453
3454 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3455 call_initPhase1(CHECK);
3456
3457 // get the Java runtime name after java.lang.System is initialized
3458 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3459 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3460
3461 // an instance of OutOfMemory exception has been allocated earlier
3462 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3463 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3464 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3465 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3466 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3467 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3468 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3469 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3470 }
3471
3472 void Threads::initialize_jsr292_core_classes(TRAPS) {
3473 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3474
3475 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3476 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3477 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3478 }
3479
3480 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3481 extern void JDK_Version_init();
3482
3483 // Preinitialize version info.
3484 VM_Version::early_initialize();
3485
3486 // Check version
3487 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3488
3489 // Initialize library-based TLS
3490 ThreadLocalStorage::init();
3491
3492 // Initialize the output stream module
3493 ostream_init();
3494
3495 // Process java launcher properties.
3496 Arguments::process_sun_java_launcher_properties(args);
3497
3498 // Initialize the os module
3499 os::init();
3500
3501 // Record VM creation timing statistics
3502 TraceVmCreationTime create_vm_timer;
3503 create_vm_timer.start();
3504
3505 // Initialize system properties.
3506 Arguments::init_system_properties();
3507
3508 // So that JDK version can be used as a discriminator when parsing arguments
3509 JDK_Version_init();
3510
3511 // Update/Initialize System properties after JDK version number is known
3512 Arguments::init_version_specific_system_properties();
3513
3514 // Make sure to initialize log configuration *before* parsing arguments
3515 LogConfiguration::initialize(create_vm_timer.begin_time());
3516
3517 // Parse arguments
3518 jint parse_result = Arguments::parse(args);
3519 if (parse_result != JNI_OK) return parse_result;
3520
3521 os::init_before_ergo();
3522
3523 jint ergo_result = Arguments::apply_ergo();
3524 if (ergo_result != JNI_OK) return ergo_result;
3525
3526 // Final check of all ranges after ergonomics which may change values.
3527 if (!CommandLineFlagRangeList::check_ranges()) {
3528 return JNI_EINVAL;
3529 }
3530
3531 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3532 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3533 if (!constraint_result) {
3534 return JNI_EINVAL;
3535 }
3536
3537 if (PauseAtStartup) {
3538 os::pause();
3539 }
3540
3541 HOTSPOT_VM_INIT_BEGIN();
3542
3543 // Timing (must come after argument parsing)
3544 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3545
3546 // Initialize the os module after parsing the args
3547 jint os_init_2_result = os::init_2();
3548 if (os_init_2_result != JNI_OK) return os_init_2_result;
3549
3550 jint adjust_after_os_result = Arguments::adjust_after_os();
3551 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3552
3553 // Initialize output stream logging
3554 ostream_init_log();
3555
3556 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3557 // Must be before create_vm_init_agents()
3558 if (Arguments::init_libraries_at_startup()) {
3559 convert_vm_init_libraries_to_agents();
3560 }
3561
3562 // Launch -agentlib/-agentpath and converted -Xrun agents
3563 if (Arguments::init_agents_at_startup()) {
3564 create_vm_init_agents();
3565 }
3566
3567 // Initialize Threads state
3568 _thread_list = NULL;
3569 _number_of_threads = 0;
3570 _number_of_non_daemon_threads = 0;
3571
3572 // Initialize global data structures and create system classes in heap
3573 vm_init_globals();
3574
3575 #if INCLUDE_JVMCI
3576 if (JVMCICounterSize > 0) {
3577 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3578 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3579 } else {
3580 JavaThread::_jvmci_old_thread_counters = NULL;
3581 }
3582 #endif // INCLUDE_JVMCI
3583
3584 // Attach the main thread to this os thread
3585 JavaThread* main_thread = new JavaThread();
3586 main_thread->set_thread_state(_thread_in_vm);
3587 main_thread->initialize_thread_current();
3588 // must do this before set_active_handles
3589 main_thread->record_stack_base_and_size();
3590 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3591
3592 if (!main_thread->set_as_starting_thread()) {
3593 vm_shutdown_during_initialization(
3594 "Failed necessary internal allocation. Out of swap space");
3595 delete main_thread;
3596 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3597 return JNI_ENOMEM;
3598 }
3599
3600 // Enable guard page *after* os::create_main_thread(), otherwise it would
3601 // crash Linux VM, see notes in os_linux.cpp.
3602 main_thread->create_stack_guard_pages();
3603
3604 // Initialize Java-Level synchronization subsystem
3605 ObjectMonitor::Initialize();
3606
3607 // Initialize global modules
3608 jint status = init_globals();
3609 if (status != JNI_OK) {
3610 delete main_thread;
3611 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3612 return status;
3613 }
3614
3615 if (TRACE_INITIALIZE() != JNI_OK) {
3616 vm_exit_during_initialization("Failed to initialize tracing backend");
3617 }
3618
3619 // Should be done after the heap is fully created
3620 main_thread->cache_global_variables();
3621
3622 HandleMark hm;
3623
3624 { MutexLocker mu(Threads_lock);
3625 Threads::add(main_thread);
3626 }
3627
3628 // Any JVMTI raw monitors entered in onload will transition into
3629 // real raw monitor. VM is setup enough here for raw monitor enter.
3630 JvmtiExport::transition_pending_onload_raw_monitors();
3631
3632 // Create the VMThread
3633 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3634
3635 VMThread::create();
3636 Thread* vmthread = VMThread::vm_thread();
3637
3638 if (!os::create_thread(vmthread, os::vm_thread)) {
3639 vm_exit_during_initialization("Cannot create VM thread. "
3640 "Out of system resources.");
3641 }
3642
3643 // Wait for the VM thread to become ready, and VMThread::run to initialize
3644 // Monitors can have spurious returns, must always check another state flag
3645 {
3646 MutexLocker ml(Notify_lock);
3647 os::start_thread(vmthread);
3648 while (vmthread->active_handles() == NULL) {
3649 Notify_lock->wait();
3650 }
3651 }
3652 }
3653
3654 assert(Universe::is_fully_initialized(), "not initialized");
3655 if (VerifyDuringStartup) {
3656 // Make sure we're starting with a clean slate.
3657 VM_Verify verify_op;
3658 VMThread::execute(&verify_op);
3659 }
3660
3661 Thread* THREAD = Thread::current();
3662
3663 // At this point, the Universe is initialized, but we have not executed
3664 // any byte code. Now is a good time (the only time) to dump out the
3665 // internal state of the JVM for sharing.
3666 if (DumpSharedSpaces) {
3667 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3668 ShouldNotReachHere();
3669 }
3670
3671 // Always call even when there are not JVMTI environments yet, since environments
3672 // may be attached late and JVMTI must track phases of VM execution
3673 JvmtiExport::enter_early_start_phase();
3674
3675 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3676 JvmtiExport::post_early_vm_start();
3677
3678 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3679
3680 // We need this for ClassDataSharing - the initial vm.info property is set
3681 // with the default value of CDS "sharing" which may be reset through
3682 // command line options.
3683 reset_vm_info_property(CHECK_JNI_ERR);
3684
3685 quicken_jni_functions();
3686
3687 // No more stub generation allowed after that point.
3688 StubCodeDesc::freeze();
3689
3690 // Set flag that basic initialization has completed. Used by exceptions and various
3691 // debug stuff, that does not work until all basic classes have been initialized.
3692 set_init_completed();
3693
3694 LogConfiguration::post_initialize();
3695 Metaspace::post_initialize();
3696
3697 HOTSPOT_VM_INIT_END();
3698
3699 // record VM initialization completion time
3700 #if INCLUDE_MANAGEMENT
3701 Management::record_vm_init_completed();
3702 #endif // INCLUDE_MANAGEMENT
3703
3704 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3705 // set_init_completed has just been called, causing exceptions not to be shortcut
3706 // anymore. We call vm_exit_during_initialization directly instead.
3707
3708 // Initialize reference pending list locker
3709 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3710 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3711
3712 // Signal Dispatcher needs to be started before VMInit event is posted
3713 os::signal_init();
3714
3715 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3716 if (!DisableAttachMechanism) {
3717 AttachListener::vm_start();
3718 if (StartAttachListener || AttachListener::init_at_startup()) {
3719 AttachListener::init();
3720 }
3721 }
3722
3723 // Launch -Xrun agents
3724 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3725 // back-end can launch with -Xdebug -Xrunjdwp.
3726 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3727 create_vm_init_libraries();
3728 }
3729
3730 if (CleanChunkPoolAsync) {
3731 Chunk::start_chunk_pool_cleaner_task();
3732 }
3733
3734 // initialize compiler(s)
3735 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3736 CompileBroker::compilation_init(CHECK_JNI_ERR);
3737 #endif
3738
3739 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3740 // It is done after compilers are initialized, because otherwise compilations of
3741 // signature polymorphic MH intrinsics can be missed
3742 // (see SystemDictionary::find_method_handle_intrinsic).
3743 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3744
3745 // This will initialize the module system. Only java.base classes can be
3746 // loaded until phase 2 completes
3747 call_initPhase2(CHECK_JNI_ERR);
3748
3749 // Always call even when there are not JVMTI environments yet, since environments
3750 // may be attached late and JVMTI must track phases of VM execution
3751 JvmtiExport::enter_start_phase();
3752
3753 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3754 JvmtiExport::post_vm_start();
3755
3756 // Final system initialization including security manager and system class loader
3757 call_initPhase3(CHECK_JNI_ERR);
3758
3759 // cache the system class loader
3760 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3761
3762 // Always call even when there are not JVMTI environments yet, since environments
3763 // may be attached late and JVMTI must track phases of VM execution
3764 JvmtiExport::enter_live_phase();
3765
3766 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3767 JvmtiExport::post_vm_initialized();
3768
3769 if (TRACE_START() != JNI_OK) {
3770 vm_exit_during_initialization("Failed to start tracing backend.");
3771 }
3772
3773 #if INCLUDE_MANAGEMENT
3774 Management::initialize(THREAD);
3775
3776 if (HAS_PENDING_EXCEPTION) {
3777 // management agent fails to start possibly due to
3778 // configuration problem and is responsible for printing
3779 // stack trace if appropriate. Simply exit VM.
3780 vm_exit(1);
3781 }
3782 #endif // INCLUDE_MANAGEMENT
3783
3784 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3785 if (MemProfiling) MemProfiler::engage();
3786 StatSampler::engage();
3787 if (CheckJNICalls) JniPeriodicChecker::engage();
3788
3789 BiasedLocking::init();
3790
3791 #if INCLUDE_RTM_OPT
3792 RTMLockingCounters::init();
3793 #endif
3794
3795 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3796 call_postVMInitHook(THREAD);
3797 // The Java side of PostVMInitHook.run must deal with all
3798 // exceptions and provide means of diagnosis.
3799 if (HAS_PENDING_EXCEPTION) {
3800 CLEAR_PENDING_EXCEPTION;
3801 }
3802 }
3803
3804 {
3805 MutexLocker ml(PeriodicTask_lock);
3806 // Make sure the WatcherThread can be started by WatcherThread::start()
3807 // or by dynamic enrollment.
3808 WatcherThread::make_startable();
3809 // Start up the WatcherThread if there are any periodic tasks
3810 // NOTE: All PeriodicTasks should be registered by now. If they
3811 // aren't, late joiners might appear to start slowly (we might
3812 // take a while to process their first tick).
3813 if (PeriodicTask::num_tasks() > 0) {
3814 WatcherThread::start();
3815 }
3816 }
3817
3818 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3819
3820 create_vm_timer.end();
3821 #ifdef ASSERT
3822 _vm_complete = true;
3823 #endif
3824 return JNI_OK;
3825 }
3826
3827 // type for the Agent_OnLoad and JVM_OnLoad entry points
3828 extern "C" {
3829 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3830 }
3831 // Find a command line agent library and return its entry point for
3832 // -agentlib: -agentpath: -Xrun
3833 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3834 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3835 const char *on_load_symbols[],
3836 size_t num_symbol_entries) {
3837 OnLoadEntry_t on_load_entry = NULL;
3838 void *library = NULL;
3839
3840 if (!agent->valid()) {
3841 char buffer[JVM_MAXPATHLEN];
3842 char ebuf[1024] = "";
3843 const char *name = agent->name();
3844 const char *msg = "Could not find agent library ";
3845
3846 // First check to see if agent is statically linked into executable
3847 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3848 library = agent->os_lib();
3849 } else if (agent->is_absolute_path()) {
3850 library = os::dll_load(name, ebuf, sizeof ebuf);
3851 if (library == NULL) {
3852 const char *sub_msg = " in absolute path, with error: ";
3853 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3854 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3855 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3856 // If we can't find the agent, exit.
3857 vm_exit_during_initialization(buf, NULL);
3858 FREE_C_HEAP_ARRAY(char, buf);
3859 }
3860 } else {
3861 // Try to load the agent from the standard dll directory
3862 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3863 name)) {
3864 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3865 }
3866 if (library == NULL) { // Try the local directory
3867 char ns[1] = {0};
3868 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3869 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3870 }
3871 if (library == NULL) {
3872 const char *sub_msg = " on the library path, with error: ";
3873 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3874 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3875 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3876 // If we can't find the agent, exit.
3877 vm_exit_during_initialization(buf, NULL);
3878 FREE_C_HEAP_ARRAY(char, buf);
3879 }
3880 }
3881 }
3882 agent->set_os_lib(library);
3883 agent->set_valid();
3884 }
3885
3886 // Find the OnLoad function.
3887 on_load_entry =
3888 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3889 false,
3890 on_load_symbols,
3891 num_symbol_entries));
3892 return on_load_entry;
3893 }
3894
3895 // Find the JVM_OnLoad entry point
3896 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3897 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3898 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3899 }
3900
3901 // Find the Agent_OnLoad entry point
3902 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3903 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3904 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3905 }
3906
3907 // For backwards compatibility with -Xrun
3908 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3909 // treated like -agentpath:
3910 // Must be called before agent libraries are created
3911 void Threads::convert_vm_init_libraries_to_agents() {
3912 AgentLibrary* agent;
3913 AgentLibrary* next;
3914
3915 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3916 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3917 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3918
3919 // If there is an JVM_OnLoad function it will get called later,
3920 // otherwise see if there is an Agent_OnLoad
3921 if (on_load_entry == NULL) {
3922 on_load_entry = lookup_agent_on_load(agent);
3923 if (on_load_entry != NULL) {
3924 // switch it to the agent list -- so that Agent_OnLoad will be called,
3925 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3926 Arguments::convert_library_to_agent(agent);
3927 } else {
3928 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3929 }
3930 }
3931 }
3932 }
3933
3934 // Create agents for -agentlib: -agentpath: and converted -Xrun
3935 // Invokes Agent_OnLoad
3936 // Called very early -- before JavaThreads exist
3937 void Threads::create_vm_init_agents() {
3938 extern struct JavaVM_ main_vm;
3939 AgentLibrary* agent;
3940
3941 JvmtiExport::enter_onload_phase();
3942
3943 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3944 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3945
3946 if (on_load_entry != NULL) {
3947 // Invoke the Agent_OnLoad function
3948 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3949 if (err != JNI_OK) {
3950 vm_exit_during_initialization("agent library failed to init", agent->name());
3951 }
3952 } else {
3953 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3954 }
3955 }
3956 JvmtiExport::enter_primordial_phase();
3957 }
3958
3959 extern "C" {
3960 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3961 }
3962
3963 void Threads::shutdown_vm_agents() {
3964 // Send any Agent_OnUnload notifications
3965 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3966 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3967 extern struct JavaVM_ main_vm;
3968 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3969
3970 // Find the Agent_OnUnload function.
3971 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3972 os::find_agent_function(agent,
3973 false,
3974 on_unload_symbols,
3975 num_symbol_entries));
3976
3977 // Invoke the Agent_OnUnload function
3978 if (unload_entry != NULL) {
3979 JavaThread* thread = JavaThread::current();
3980 ThreadToNativeFromVM ttn(thread);
3981 HandleMark hm(thread);
3982 (*unload_entry)(&main_vm);
3983 }
3984 }
3985 }
3986
3987 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3988 // Invokes JVM_OnLoad
3989 void Threads::create_vm_init_libraries() {
3990 extern struct JavaVM_ main_vm;
3991 AgentLibrary* agent;
3992
3993 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3994 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3995
3996 if (on_load_entry != NULL) {
3997 // Invoke the JVM_OnLoad function
3998 JavaThread* thread = JavaThread::current();
3999 ThreadToNativeFromVM ttn(thread);
4000 HandleMark hm(thread);
4001 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4002 if (err != JNI_OK) {
4003 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4004 }
4005 } else {
4006 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4007 }
4008 }
4009 }
4010
4011 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4012 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4013
4014 JavaThread* java_thread = NULL;
4015 // Sequential search for now. Need to do better optimization later.
4016 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4017 oop tobj = thread->threadObj();
4018 if (!thread->is_exiting() &&
4019 tobj != NULL &&
4020 java_tid == java_lang_Thread::thread_id(tobj)) {
4021 java_thread = thread;
4022 break;
4023 }
4024 }
4025 return java_thread;
4026 }
4027
4028
4029 // Last thread running calls java.lang.Shutdown.shutdown()
4030 void JavaThread::invoke_shutdown_hooks() {
4031 HandleMark hm(this);
4032
4033 // We could get here with a pending exception, if so clear it now.
4034 if (this->has_pending_exception()) {
4035 this->clear_pending_exception();
4036 }
4037
4038 EXCEPTION_MARK;
4039 Klass* k =
4040 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4041 THREAD);
4042 if (k != NULL) {
4043 // SystemDictionary::resolve_or_null will return null if there was
4044 // an exception. If we cannot load the Shutdown class, just don't
4045 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4046 // and finalizers (if runFinalizersOnExit is set) won't be run.
4047 // Note that if a shutdown hook was registered or runFinalizersOnExit
4048 // was called, the Shutdown class would have already been loaded
4049 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4050 instanceKlassHandle shutdown_klass (THREAD, k);
4051 JavaValue result(T_VOID);
4052 JavaCalls::call_static(&result,
4053 shutdown_klass,
4054 vmSymbols::shutdown_method_name(),
4055 vmSymbols::void_method_signature(),
4056 THREAD);
4057 }
4058 CLEAR_PENDING_EXCEPTION;
4059 }
4060
4061 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4062 // the program falls off the end of main(). Another VM exit path is through
4063 // vm_exit() when the program calls System.exit() to return a value or when
4064 // there is a serious error in VM. The two shutdown paths are not exactly
4065 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4066 // and VM_Exit op at VM level.
4067 //
4068 // Shutdown sequence:
4069 // + Shutdown native memory tracking if it is on
4070 // + Wait until we are the last non-daemon thread to execute
4071 // <-- every thing is still working at this moment -->
4072 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4073 // shutdown hooks, run finalizers if finalization-on-exit
4074 // + Call before_exit(), prepare for VM exit
4075 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4076 // currently the only user of this mechanism is File.deleteOnExit())
4077 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4078 // post thread end and vm death events to JVMTI,
4079 // stop signal thread
4080 // + Call JavaThread::exit(), it will:
4081 // > release JNI handle blocks, remove stack guard pages
4082 // > remove this thread from Threads list
4083 // <-- no more Java code from this thread after this point -->
4084 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4085 // the compiler threads at safepoint
4086 // <-- do not use anything that could get blocked by Safepoint -->
4087 // + Disable tracing at JNI/JVM barriers
4088 // + Set _vm_exited flag for threads that are still running native code
4089 // + Delete this thread
4090 // + Call exit_globals()
4091 // > deletes tty
4092 // > deletes PerfMemory resources
4093 // + Return to caller
4094
4095 bool Threads::destroy_vm() {
4096 JavaThread* thread = JavaThread::current();
4097
4098 #ifdef ASSERT
4099 _vm_complete = false;
4100 #endif
4101 // Wait until we are the last non-daemon thread to execute
4102 { MutexLocker nu(Threads_lock);
4103 while (Threads::number_of_non_daemon_threads() > 1)
4104 // This wait should make safepoint checks, wait without a timeout,
4105 // and wait as a suspend-equivalent condition.
4106 //
4107 // Note: If the FlatProfiler is running and this thread is waiting
4108 // for another non-daemon thread to finish, then the FlatProfiler
4109 // is waiting for the external suspend request on this thread to
4110 // complete. wait_for_ext_suspend_completion() will eventually
4111 // timeout, but that takes time. Making this wait a suspend-
4112 // equivalent condition solves that timeout problem.
4113 //
4114 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4115 Mutex::_as_suspend_equivalent_flag);
4116 }
4117
4118 // Hang forever on exit if we are reporting an error.
4119 if (ShowMessageBoxOnError && is_error_reported()) {
4120 os::infinite_sleep();
4121 }
4122 os::wait_for_keypress_at_exit();
4123
4124 // run Java level shutdown hooks
4125 thread->invoke_shutdown_hooks();
4126
4127 before_exit(thread);
4128
4129 thread->exit(true);
4130
4131 // Stop VM thread.
4132 {
4133 // 4945125 The vm thread comes to a safepoint during exit.
4134 // GC vm_operations can get caught at the safepoint, and the
4135 // heap is unparseable if they are caught. Grab the Heap_lock
4136 // to prevent this. The GC vm_operations will not be able to
4137 // queue until after the vm thread is dead. After this point,
4138 // we'll never emerge out of the safepoint before the VM exits.
4139
4140 MutexLocker ml(Heap_lock);
4141
4142 VMThread::wait_for_vm_thread_exit();
4143 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4144 VMThread::destroy();
4145 }
4146
4147 // clean up ideal graph printers
4148 #if defined(COMPILER2) && !defined(PRODUCT)
4149 IdealGraphPrinter::clean_up();
4150 #endif
4151
4152 // Now, all Java threads are gone except daemon threads. Daemon threads
4153 // running Java code or in VM are stopped by the Safepoint. However,
4154 // daemon threads executing native code are still running. But they
4155 // will be stopped at native=>Java/VM barriers. Note that we can't
4156 // simply kill or suspend them, as it is inherently deadlock-prone.
4157
4158 VM_Exit::set_vm_exited();
4159
4160 notify_vm_shutdown();
4161
4162 delete thread;
4163
4164 #if INCLUDE_JVMCI
4165 if (JVMCICounterSize > 0) {
4166 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4167 }
4168 #endif
4169
4170 // exit_globals() will delete tty
4171 exit_globals();
4172
4173 LogConfiguration::finalize();
4174
4175 return true;
4176 }
4177
4178
4179 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4180 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4181 return is_supported_jni_version(version);
4182 }
4183
4184
4185 jboolean Threads::is_supported_jni_version(jint version) {
4186 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4187 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4188 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4189 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4190 if (version == JNI_VERSION_9) return JNI_TRUE;
4191 return JNI_FALSE;
4192 }
4193
4194
4195 void Threads::add(JavaThread* p, bool force_daemon) {
4196 // The threads lock must be owned at this point
4197 assert_locked_or_safepoint(Threads_lock);
4198
4199 // See the comment for this method in thread.hpp for its purpose and
4200 // why it is called here.
4201 p->initialize_queues();
4202 p->set_next(_thread_list);
4203 _thread_list = p;
4204 _number_of_threads++;
4205 oop threadObj = p->threadObj();
4206 bool daemon = true;
4207 // Bootstrapping problem: threadObj can be null for initial
4208 // JavaThread (or for threads attached via JNI)
4209 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4210 _number_of_non_daemon_threads++;
4211 daemon = false;
4212 }
4213
4214 ThreadService::add_thread(p, daemon);
4215
4216 // Possible GC point.
4217 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4218 }
4219
4220 void Threads::remove(JavaThread* p) {
4221 // Extra scope needed for Thread_lock, so we can check
4222 // that we do not remove thread without safepoint code notice
4223 { MutexLocker ml(Threads_lock);
4224
4225 assert(includes(p), "p must be present");
4226
4227 JavaThread* current = _thread_list;
4228 JavaThread* prev = NULL;
4229
4230 while (current != p) {
4231 prev = current;
4232 current = current->next();
4233 }
4234
4235 if (prev) {
4236 prev->set_next(current->next());
4237 } else {
4238 _thread_list = p->next();
4239 }
4240 _number_of_threads--;
4241 oop threadObj = p->threadObj();
4242 bool daemon = true;
4243 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4244 _number_of_non_daemon_threads--;
4245 daemon = false;
4246
4247 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4248 // on destroy_vm will wake up.
4249 if (number_of_non_daemon_threads() == 1) {
4250 Threads_lock->notify_all();
4251 }
4252 }
4253 ThreadService::remove_thread(p, daemon);
4254
4255 // Make sure that safepoint code disregard this thread. This is needed since
4256 // the thread might mess around with locks after this point. This can cause it
4257 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4258 // of this thread since it is removed from the queue.
4259 p->set_terminated_value();
4260 } // unlock Threads_lock
4261
4262 // Since Events::log uses a lock, we grab it outside the Threads_lock
4263 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4264 }
4265
4266 // Threads_lock must be held when this is called (or must be called during a safepoint)
4267 bool Threads::includes(JavaThread* p) {
4268 assert(Threads_lock->is_locked(), "sanity check");
4269 ALL_JAVA_THREADS(q) {
4270 if (q == p) {
4271 return true;
4272 }
4273 }
4274 return false;
4275 }
4276
4277 // Operations on the Threads list for GC. These are not explicitly locked,
4278 // but the garbage collector must provide a safe context for them to run.
4279 // In particular, these things should never be called when the Threads_lock
4280 // is held by some other thread. (Note: the Safepoint abstraction also
4281 // uses the Threads_lock to guarantee this property. It also makes sure that
4282 // all threads gets blocked when exiting or starting).
4283
4284 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4285 ALL_JAVA_THREADS(p) {
4286 p->oops_do(f, cld_f, cf);
4287 }
4288 VMThread::vm_thread()->oops_do(f, cld_f, cf);
4289 }
4290
4291 void Threads::change_thread_claim_parity() {
4292 // Set the new claim parity.
4293 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4294 "Not in range.");
4295 _thread_claim_parity++;
4296 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4297 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4298 "Not in range.");
4299 }
4300
4301 #ifdef ASSERT
4302 void Threads::assert_all_threads_claimed() {
4303 ALL_JAVA_THREADS(p) {
4304 const int thread_parity = p->oops_do_parity();
4305 assert((thread_parity == _thread_claim_parity),
4306 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4307 }
4308 }
4309 #endif // ASSERT
4310
4311 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4312 int cp = Threads::thread_claim_parity();
4313 ALL_JAVA_THREADS(p) {
4314 if (p->claim_oops_do(is_par, cp)) {
4315 p->oops_do(f, cld_f, cf);
4316 }
4317 }
4318 VMThread* vmt = VMThread::vm_thread();
4319 if (vmt->claim_oops_do(is_par, cp)) {
4320 vmt->oops_do(f, cld_f, cf);
4321 }
4322 }
4323
4324 #if INCLUDE_ALL_GCS
4325 // Used by ParallelScavenge
4326 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4327 ALL_JAVA_THREADS(p) {
4328 q->enqueue(new ThreadRootsTask(p));
4329 }
4330 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4331 }
4332
4333 // Used by Parallel Old
4334 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4335 ALL_JAVA_THREADS(p) {
4336 q->enqueue(new ThreadRootsMarkingTask(p));
4337 }
4338 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4339 }
4340 #endif // INCLUDE_ALL_GCS
4341
4342 void Threads::nmethods_do(CodeBlobClosure* cf) {
4343 ALL_JAVA_THREADS(p) {
4344 p->nmethods_do(cf);
4345 }
4346 VMThread::vm_thread()->nmethods_do(cf);
4347 }
4348
4349 void Threads::metadata_do(void f(Metadata*)) {
4350 ALL_JAVA_THREADS(p) {
4351 p->metadata_do(f);
4352 }
4353 }
4354
4355 class ThreadHandlesClosure : public ThreadClosure {
4356 void (*_f)(Metadata*);
4357 public:
4358 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4359 virtual void do_thread(Thread* thread) {
4360 thread->metadata_handles_do(_f);
4361 }
4362 };
4363
4364 void Threads::metadata_handles_do(void f(Metadata*)) {
4365 // Only walk the Handles in Thread.
4366 ThreadHandlesClosure handles_closure(f);
4367 threads_do(&handles_closure);
4368 }
4369
4370 void Threads::deoptimized_wrt_marked_nmethods() {
4371 ALL_JAVA_THREADS(p) {
4372 p->deoptimized_wrt_marked_nmethods();
4373 }
4374 }
4375
4376
4377 // Get count Java threads that are waiting to enter the specified monitor.
4378 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4379 address monitor,
4380 bool doLock) {
4381 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4382 "must grab Threads_lock or be at safepoint");
4383 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4384
4385 int i = 0;
4386 {
4387 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4388 ALL_JAVA_THREADS(p) {
4389 if (!p->can_call_java()) continue;
4390
4391 address pending = (address)p->current_pending_monitor();
4392 if (pending == monitor) { // found a match
4393 if (i < count) result->append(p); // save the first count matches
4394 i++;
4395 }
4396 }
4397 }
4398 return result;
4399 }
4400
4401
4402 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4403 bool doLock) {
4404 assert(doLock ||
4405 Threads_lock->owned_by_self() ||
4406 SafepointSynchronize::is_at_safepoint(),
4407 "must grab Threads_lock or be at safepoint");
4408
4409 // NULL owner means not locked so we can skip the search
4410 if (owner == NULL) return NULL;
4411
4412 {
4413 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4414 ALL_JAVA_THREADS(p) {
4415 // first, see if owner is the address of a Java thread
4416 if (owner == (address)p) return p;
4417 }
4418 }
4419 // Cannot assert on lack of success here since this function may be
4420 // used by code that is trying to report useful problem information
4421 // like deadlock detection.
4422 if (UseHeavyMonitors) return NULL;
4423
4424 // If we didn't find a matching Java thread and we didn't force use of
4425 // heavyweight monitors, then the owner is the stack address of the
4426 // Lock Word in the owning Java thread's stack.
4427 //
4428 JavaThread* the_owner = NULL;
4429 {
4430 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4431 ALL_JAVA_THREADS(q) {
4432 if (q->is_lock_owned(owner)) {
4433 the_owner = q;
4434 break;
4435 }
4436 }
4437 }
4438 // cannot assert on lack of success here; see above comment
4439 return the_owner;
4440 }
4441
4442 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4443 void Threads::print_on(outputStream* st, bool print_stacks,
4444 bool internal_format, bool print_concurrent_locks) {
4445 char buf[32];
4446 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4447
4448 st->print_cr("Full thread dump %s (%s %s):",
4449 Abstract_VM_Version::vm_name(),
4450 Abstract_VM_Version::vm_release(),
4451 Abstract_VM_Version::vm_info_string());
4452 st->cr();
4453
4454 #if INCLUDE_SERVICES
4455 // Dump concurrent locks
4456 ConcurrentLocksDump concurrent_locks;
4457 if (print_concurrent_locks) {
4458 concurrent_locks.dump_at_safepoint();
4459 }
4460 #endif // INCLUDE_SERVICES
4461
4462 ALL_JAVA_THREADS(p) {
4463 ResourceMark rm;
4464 p->print_on(st);
4465 if (print_stacks) {
4466 if (internal_format) {
4467 p->trace_stack();
4468 } else {
4469 p->print_stack_on(st);
4470 }
4471 }
4472 st->cr();
4473 #if INCLUDE_SERVICES
4474 if (print_concurrent_locks) {
4475 concurrent_locks.print_locks_on(p, st);
4476 }
4477 #endif // INCLUDE_SERVICES
4478 }
4479
4480 VMThread::vm_thread()->print_on(st);
4481 st->cr();
4482 Universe::heap()->print_gc_threads_on(st);
4483 WatcherThread* wt = WatcherThread::watcher_thread();
4484 if (wt != NULL) {
4485 wt->print_on(st);
4486 st->cr();
4487 }
4488 st->flush();
4489 }
4490
4491 // Threads::print_on_error() is called by fatal error handler. It's possible
4492 // that VM is not at safepoint and/or current thread is inside signal handler.
4493 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4494 // memory (even in resource area), it might deadlock the error handler.
4495 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4496 int buflen) {
4497 bool found_current = false;
4498 st->print_cr("Java Threads: ( => current thread )");
4499 ALL_JAVA_THREADS(thread) {
4500 bool is_current = (current == thread);
4501 found_current = found_current || is_current;
4502
4503 st->print("%s", is_current ? "=>" : " ");
4504
4505 st->print(PTR_FORMAT, p2i(thread));
4506 st->print(" ");
4507 thread->print_on_error(st, buf, buflen);
4508 st->cr();
4509 }
4510 st->cr();
4511
4512 st->print_cr("Other Threads:");
4513 if (VMThread::vm_thread()) {
4514 bool is_current = (current == VMThread::vm_thread());
4515 found_current = found_current || is_current;
4516 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4517
4518 st->print(PTR_FORMAT, p2i(VMThread::vm_thread()));
4519 st->print(" ");
4520 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4521 st->cr();
4522 }
4523 WatcherThread* wt = WatcherThread::watcher_thread();
4524 if (wt != NULL) {
4525 bool is_current = (current == wt);
4526 found_current = found_current || is_current;
4527 st->print("%s", is_current ? "=>" : " ");
4528
4529 st->print(PTR_FORMAT, p2i(wt));
4530 st->print(" ");
4531 wt->print_on_error(st, buf, buflen);
4532 st->cr();
4533 }
4534 if (!found_current) {
4535 st->cr();
4536 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4537 current->print_on_error(st, buf, buflen);
4538 st->cr();
4539 }
4540 st->cr();
4541 st->print_cr("Threads with active compile tasks:");
4542 print_threads_compiling(st, buf, buflen);
4543 }
4544
4545 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4546 ALL_JAVA_THREADS(thread) {
4547 if (thread->is_Compiler_thread()) {
4548 CompilerThread* ct = (CompilerThread*) thread;
4549 if (ct->task() != NULL) {
4550 thread->print_name_on_error(st, buf, buflen);
4551 ct->task()->print(st, NULL, true, true);
4552 }
4553 }
4554 }
4555 }
4556
4557
4558 // Internal SpinLock and Mutex
4559 // Based on ParkEvent
4560
4561 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4562 //
4563 // We employ SpinLocks _only for low-contention, fixed-length
4564 // short-duration critical sections where we're concerned
4565 // about native mutex_t or HotSpot Mutex:: latency.
4566 // The mux construct provides a spin-then-block mutual exclusion
4567 // mechanism.
4568 //
4569 // Testing has shown that contention on the ListLock guarding gFreeList
4570 // is common. If we implement ListLock as a simple SpinLock it's common
4571 // for the JVM to devolve to yielding with little progress. This is true
4572 // despite the fact that the critical sections protected by ListLock are
4573 // extremely short.
4574 //
4575 // TODO-FIXME: ListLock should be of type SpinLock.
4576 // We should make this a 1st-class type, integrated into the lock
4577 // hierarchy as leaf-locks. Critically, the SpinLock structure
4578 // should have sufficient padding to avoid false-sharing and excessive
4579 // cache-coherency traffic.
4580
4581
4582 typedef volatile int SpinLockT;
4583
4584 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4585 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4586 return; // normal fast-path return
4587 }
4588
4589 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4590 TEVENT(SpinAcquire - ctx);
4591 int ctr = 0;
4592 int Yields = 0;
4593 for (;;) {
4594 while (*adr != 0) {
4595 ++ctr;
4596 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4597 if (Yields > 5) {
4598 os::naked_short_sleep(1);
4599 } else {
4600 os::naked_yield();
4601 ++Yields;
4602 }
4603 } else {
4604 SpinPause();
4605 }
4606 }
4607 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4608 }
4609 }
4610
4611 void Thread::SpinRelease(volatile int * adr) {
4612 assert(*adr != 0, "invariant");
4613 OrderAccess::fence(); // guarantee at least release consistency.
4614 // Roach-motel semantics.
4615 // It's safe if subsequent LDs and STs float "up" into the critical section,
4616 // but prior LDs and STs within the critical section can't be allowed
4617 // to reorder or float past the ST that releases the lock.
4618 // Loads and stores in the critical section - which appear in program
4619 // order before the store that releases the lock - must also appear
4620 // before the store that releases the lock in memory visibility order.
4621 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4622 // the ST of 0 into the lock-word which releases the lock, so fence
4623 // more than covers this on all platforms.
4624 *adr = 0;
4625 }
4626
4627 // muxAcquire and muxRelease:
4628 //
4629 // * muxAcquire and muxRelease support a single-word lock-word construct.
4630 // The LSB of the word is set IFF the lock is held.
4631 // The remainder of the word points to the head of a singly-linked list
4632 // of threads blocked on the lock.
4633 //
4634 // * The current implementation of muxAcquire-muxRelease uses its own
4635 // dedicated Thread._MuxEvent instance. If we're interested in
4636 // minimizing the peak number of extant ParkEvent instances then
4637 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4638 // as certain invariants were satisfied. Specifically, care would need
4639 // to be taken with regards to consuming unpark() "permits".
4640 // A safe rule of thumb is that a thread would never call muxAcquire()
4641 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4642 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4643 // consume an unpark() permit intended for monitorenter, for instance.
4644 // One way around this would be to widen the restricted-range semaphore
4645 // implemented in park(). Another alternative would be to provide
4646 // multiple instances of the PlatformEvent() for each thread. One
4647 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4648 //
4649 // * Usage:
4650 // -- Only as leaf locks
4651 // -- for short-term locking only as muxAcquire does not perform
4652 // thread state transitions.
4653 //
4654 // Alternatives:
4655 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4656 // but with parking or spin-then-park instead of pure spinning.
4657 // * Use Taura-Oyama-Yonenzawa locks.
4658 // * It's possible to construct a 1-0 lock if we encode the lockword as
4659 // (List,LockByte). Acquire will CAS the full lockword while Release
4660 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4661 // acquiring threads use timers (ParkTimed) to detect and recover from
4662 // the stranding window. Thread/Node structures must be aligned on 256-byte
4663 // boundaries by using placement-new.
4664 // * Augment MCS with advisory back-link fields maintained with CAS().
4665 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4666 // The validity of the backlinks must be ratified before we trust the value.
4667 // If the backlinks are invalid the exiting thread must back-track through the
4668 // the forward links, which are always trustworthy.
4669 // * Add a successor indication. The LockWord is currently encoded as
4670 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4671 // to provide the usual futile-wakeup optimization.
4672 // See RTStt for details.
4673 // * Consider schedctl.sc_nopreempt to cover the critical section.
4674 //
4675
4676
4677 typedef volatile intptr_t MutexT; // Mux Lock-word
4678 enum MuxBits { LOCKBIT = 1 };
4679
4680 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4681 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4682 if (w == 0) return;
4683 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4684 return;
4685 }
4686
4687 TEVENT(muxAcquire - Contention);
4688 ParkEvent * const Self = Thread::current()->_MuxEvent;
4689 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4690 for (;;) {
4691 int its = (os::is_MP() ? 100 : 0) + 1;
4692
4693 // Optional spin phase: spin-then-park strategy
4694 while (--its >= 0) {
4695 w = *Lock;
4696 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4697 return;
4698 }
4699 }
4700
4701 Self->reset();
4702 Self->OnList = intptr_t(Lock);
4703 // The following fence() isn't _strictly necessary as the subsequent
4704 // CAS() both serializes execution and ratifies the fetched *Lock value.
4705 OrderAccess::fence();
4706 for (;;) {
4707 w = *Lock;
4708 if ((w & LOCKBIT) == 0) {
4709 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4710 Self->OnList = 0; // hygiene - allows stronger asserts
4711 return;
4712 }
4713 continue; // Interference -- *Lock changed -- Just retry
4714 }
4715 assert(w & LOCKBIT, "invariant");
4716 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4717 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4718 }
4719
4720 while (Self->OnList != 0) {
4721 Self->park();
4722 }
4723 }
4724 }
4725
4726 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4727 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4728 if (w == 0) return;
4729 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4730 return;
4731 }
4732
4733 TEVENT(muxAcquire - Contention);
4734 ParkEvent * ReleaseAfter = NULL;
4735 if (ev == NULL) {
4736 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4737 }
4738 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4739 for (;;) {
4740 guarantee(ev->OnList == 0, "invariant");
4741 int its = (os::is_MP() ? 100 : 0) + 1;
4742
4743 // Optional spin phase: spin-then-park strategy
4744 while (--its >= 0) {
4745 w = *Lock;
4746 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4747 if (ReleaseAfter != NULL) {
4748 ParkEvent::Release(ReleaseAfter);
4749 }
4750 return;
4751 }
4752 }
4753
4754 ev->reset();
4755 ev->OnList = intptr_t(Lock);
4756 // The following fence() isn't _strictly necessary as the subsequent
4757 // CAS() both serializes execution and ratifies the fetched *Lock value.
4758 OrderAccess::fence();
4759 for (;;) {
4760 w = *Lock;
4761 if ((w & LOCKBIT) == 0) {
4762 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4763 ev->OnList = 0;
4764 // We call ::Release while holding the outer lock, thus
4765 // artificially lengthening the critical section.
4766 // Consider deferring the ::Release() until the subsequent unlock(),
4767 // after we've dropped the outer lock.
4768 if (ReleaseAfter != NULL) {
4769 ParkEvent::Release(ReleaseAfter);
4770 }
4771 return;
4772 }
4773 continue; // Interference -- *Lock changed -- Just retry
4774 }
4775 assert(w & LOCKBIT, "invariant");
4776 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4777 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4778 }
4779
4780 while (ev->OnList != 0) {
4781 ev->park();
4782 }
4783 }
4784 }
4785
4786 // Release() must extract a successor from the list and then wake that thread.
4787 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4788 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4789 // Release() would :
4790 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4791 // (B) Extract a successor from the private list "in-hand"
4792 // (C) attempt to CAS() the residual back into *Lock over null.
4793 // If there were any newly arrived threads and the CAS() would fail.
4794 // In that case Release() would detach the RATs, re-merge the list in-hand
4795 // with the RATs and repeat as needed. Alternately, Release() might
4796 // detach and extract a successor, but then pass the residual list to the wakee.
4797 // The wakee would be responsible for reattaching and remerging before it
4798 // competed for the lock.
4799 //
4800 // Both "pop" and DMR are immune from ABA corruption -- there can be
4801 // multiple concurrent pushers, but only one popper or detacher.
4802 // This implementation pops from the head of the list. This is unfair,
4803 // but tends to provide excellent throughput as hot threads remain hot.
4804 // (We wake recently run threads first).
4805 //
4806 // All paths through muxRelease() will execute a CAS.
4807 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4808 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4809 // executed within the critical section are complete and globally visible before the
4810 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4811 void Thread::muxRelease(volatile intptr_t * Lock) {
4812 for (;;) {
4813 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4814 assert(w & LOCKBIT, "invariant");
4815 if (w == LOCKBIT) return;
4816 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4817 assert(List != NULL, "invariant");
4818 assert(List->OnList == intptr_t(Lock), "invariant");
4819 ParkEvent * const nxt = List->ListNext;
4820 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4821
4822 // The following CAS() releases the lock and pops the head element.
4823 // The CAS() also ratifies the previously fetched lock-word value.
4824 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4825 continue;
4826 }
4827 List->OnList = 0;
4828 OrderAccess::fence();
4829 List->unpark();
4830 return;
4831 }
4832 }
4833
4834
4835 void Threads::verify() {
4836 ALL_JAVA_THREADS(p) {
4837 p->verify();
4838 }
4839 VMThread* thread = VMThread::vm_thread();
4840 if (thread != NULL) thread->verify();
4841 }