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/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.inline.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/fprofiler.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/timerTrace.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/statSampler.hpp"
83 #include "runtime/stubRoutines.hpp"
84 #include "runtime/sweeper.hpp"
85 #include "runtime/task.hpp"
86 #include "runtime/thread.inline.hpp"
87 #include "runtime/threadCritical.hpp"
88 #include "runtime/vframe.hpp"
89 #include "runtime/vframeArray.hpp"
90 #include "runtime/vframe_hp.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "runtime/vm_operations.hpp"
93 #include "runtime/vm_version.hpp"
94 #include "services/attachListener.hpp"
95 #include "services/management.hpp"
96 #include "services/memTracker.hpp"
97 #include "services/threadService.hpp"
98 #include "trace/traceMacros.hpp"
99 #include "trace/tracing.hpp"
100 #include "utilities/defaultStream.hpp"
101 #include "utilities/dtrace.hpp"
102 #include "utilities/events.hpp"
103 #include "utilities/macros.hpp"
104 #include "utilities/preserveException.hpp"
105 #if INCLUDE_ALL_GCS
106 #include "gc/cms/concurrentMarkSweepThread.hpp"
107 #include "gc/g1/concurrentMarkThread.inline.hpp"
108 #include "gc/parallel/pcTasks.hpp"
109 #endif // INCLUDE_ALL_GCS
110 #if INCLUDE_JVMCI
111 #include "jvmci/jvmciCompiler.hpp"
112 #include "jvmci/jvmciRuntime.hpp"
113 #endif
114 #ifdef COMPILER1
115 #include "c1/c1_Compiler.hpp"
116 #endif
117 #ifdef COMPILER2
118 #include "opto/c2compiler.hpp"
119 #include "opto/idealGraphPrinter.hpp"
120 #endif
121 #if INCLUDE_RTM_OPT
122 #include "runtime/rtmLocking.hpp"
123 #endif
124
125 // Initialization after module runtime initialization
126 void universe_post_module_init(); // must happen after call_initPhase2
127
128 #ifdef DTRACE_ENABLED
129
130 // Only bother with this argument setup if dtrace is available
131
132 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
133 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
134
135 #define DTRACE_THREAD_PROBE(probe, javathread) \
136 { \
137 ResourceMark rm(this); \
138 int len = 0; \
139 const char* name = (javathread)->get_thread_name(); \
140 len = strlen(name); \
141 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
142 (char *) name, len, \
143 java_lang_Thread::thread_id((javathread)->threadObj()), \
144 (uintptr_t) (javathread)->osthread()->thread_id(), \
145 java_lang_Thread::is_daemon((javathread)->threadObj())); \
146 }
147
148 #else // ndef DTRACE_ENABLED
149
150 #define DTRACE_THREAD_PROBE(probe, javathread)
151
152 #endif // ndef DTRACE_ENABLED
153
154 #ifndef USE_LIBRARY_BASED_TLS_ONLY
155 // Current thread is maintained as a thread-local variable
156 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
157 #endif
158 // Class hierarchy
159 // - Thread
160 // - VMThread
161 // - WatcherThread
162 // - ConcurrentMarkSweepThread
163 // - JavaThread
164 // - CompilerThread
165
166 // ======= Thread ========
167 // Support for forcing alignment of thread objects for biased locking
168 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
169 if (UseBiasedLocking) {
170 const int alignment = markOopDesc::biased_lock_alignment;
171 size_t aligned_size = size + (alignment - sizeof(intptr_t));
172 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
173 : AllocateHeap(aligned_size, flags, CURRENT_PC,
174 AllocFailStrategy::RETURN_NULL);
175 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
176 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
177 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
178 "JavaThread alignment code overflowed allocated storage");
179 if (aligned_addr != real_malloc_addr) {
180 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
181 p2i(real_malloc_addr),
182 p2i(aligned_addr));
183 }
184 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
185 return aligned_addr;
186 } else {
187 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
188 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
189 }
190 }
191
192 void Thread::operator delete(void* p) {
193 if (UseBiasedLocking) {
194 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
195 FreeHeap(real_malloc_addr);
196 } else {
197 FreeHeap(p);
198 }
199 }
200
201
202 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
203 // JavaThread
204
205
206 Thread::Thread() {
207 // stack and get_thread
208 set_stack_base(NULL);
209 set_stack_size(0);
210 set_self_raw_id(0);
211 set_lgrp_id(-1);
212 DEBUG_ONLY(clear_suspendible_thread();)
213
214 // allocated data structures
215 set_osthread(NULL);
216 set_resource_area(new (mtThread)ResourceArea());
217 DEBUG_ONLY(_current_resource_mark = NULL;)
218 set_handle_area(new (mtThread) HandleArea(NULL));
219 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
220 set_active_handles(NULL);
221 set_free_handle_block(NULL);
222 set_last_handle_mark(NULL);
223
224 // This initial value ==> never claimed.
225 _oops_do_parity = 0;
226
227 // the handle mark links itself to last_handle_mark
228 new HandleMark(this);
229
230 // plain initialization
231 debug_only(_owned_locks = NULL;)
232 debug_only(_allow_allocation_count = 0;)
233 NOT_PRODUCT(_allow_safepoint_count = 0;)
234 NOT_PRODUCT(_skip_gcalot = false;)
235 _jvmti_env_iteration_count = 0;
236 set_allocated_bytes(0);
237 _vm_operation_started_count = 0;
238 _vm_operation_completed_count = 0;
239 _current_pending_monitor = NULL;
240 _current_pending_monitor_is_from_java = true;
241 _current_waiting_monitor = NULL;
242 _num_nested_signal = 0;
243 omFreeList = NULL;
244 omFreeCount = 0;
245 omFreeProvision = 32;
246 omInUseList = NULL;
247 omInUseCount = 0;
248
249 #ifdef ASSERT
250 _visited_for_critical_count = false;
251 #endif
252
253 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
254 Monitor::_safepoint_check_sometimes);
255 _suspend_flags = 0;
256
257 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
258 _hashStateX = os::random();
259 _hashStateY = 842502087;
260 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
261 _hashStateW = 273326509;
262
263 _OnTrap = 0;
264 _schedctl = NULL;
265 _Stalled = 0;
266 _TypeTag = 0x2BAD;
267
268 // Many of the following fields are effectively final - immutable
269 // Note that nascent threads can't use the Native Monitor-Mutex
270 // construct until the _MutexEvent is initialized ...
271 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
272 // we might instead use a stack of ParkEvents that we could provision on-demand.
273 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
274 // and ::Release()
275 _ParkEvent = ParkEvent::Allocate(this);
276 _SleepEvent = ParkEvent::Allocate(this);
277 _MutexEvent = ParkEvent::Allocate(this);
278 _MuxEvent = ParkEvent::Allocate(this);
279
280 #ifdef CHECK_UNHANDLED_OOPS
281 if (CheckUnhandledOops) {
282 _unhandled_oops = new UnhandledOops(this);
283 }
284 #endif // CHECK_UNHANDLED_OOPS
285 #ifdef ASSERT
286 if (UseBiasedLocking) {
287 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
288 assert(this == _real_malloc_address ||
289 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
290 "bug in forced alignment of thread objects");
291 }
292 #endif // ASSERT
293 }
294
295 void Thread::initialize_thread_current() {
296 #ifndef USE_LIBRARY_BASED_TLS_ONLY
297 assert(_thr_current == NULL, "Thread::current already initialized");
298 _thr_current = this;
299 #endif
300 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
301 ThreadLocalStorage::set_thread(this);
302 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
303 }
304
305 void Thread::clear_thread_current() {
306 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
307 #ifndef USE_LIBRARY_BASED_TLS_ONLY
308 _thr_current = NULL;
309 #endif
310 ThreadLocalStorage::set_thread(NULL);
311 }
312
313 void Thread::record_stack_base_and_size() {
314 set_stack_base(os::current_stack_base());
315 set_stack_size(os::current_stack_size());
316 // CR 7190089: on Solaris, primordial thread's stack is adjusted
317 // in initialize_thread(). Without the adjustment, stack size is
318 // incorrect if stack is set to unlimited (ulimit -s unlimited).
319 // So far, only Solaris has real implementation of initialize_thread().
320 //
321 // set up any platform-specific state.
322 os::initialize_thread(this);
323
324 // Set stack limits after thread is initialized.
325 if (is_Java_thread()) {
326 ((JavaThread*) this)->set_stack_overflow_limit();
327 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
328 }
329 #if INCLUDE_NMT
330 // record thread's native stack, stack grows downward
331 MemTracker::record_thread_stack(stack_end(), stack_size());
332 #endif // INCLUDE_NMT
333 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
334 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
335 os::current_thread_id(), p2i(stack_base() - stack_size()),
336 p2i(stack_base()), stack_size()/1024);
337 }
338
339
340 Thread::~Thread() {
341 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
342 ObjectSynchronizer::omFlush(this);
343
344 EVENT_THREAD_DESTRUCT(this);
345
346 // stack_base can be NULL if the thread is never started or exited before
347 // record_stack_base_and_size called. Although, we would like to ensure
348 // that all started threads do call record_stack_base_and_size(), there is
349 // not proper way to enforce that.
350 #if INCLUDE_NMT
351 if (_stack_base != NULL) {
352 MemTracker::release_thread_stack(stack_end(), stack_size());
353 #ifdef ASSERT
354 set_stack_base(NULL);
355 #endif
356 }
357 #endif // INCLUDE_NMT
358
359 // deallocate data structures
360 delete resource_area();
361 // since the handle marks are using the handle area, we have to deallocated the root
362 // handle mark before deallocating the thread's handle area,
363 assert(last_handle_mark() != NULL, "check we have an element");
364 delete last_handle_mark();
365 assert(last_handle_mark() == NULL, "check we have reached the end");
366
367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
368 // We NULL out the fields for good hygiene.
369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
373
374 delete handle_area();
375 delete metadata_handles();
376
377 // SR_handler uses this as a termination indicator -
378 // needs to happen before os::free_thread()
379 delete _SR_lock;
380 _SR_lock = NULL;
381
382 // osthread() can be NULL, if creation of thread failed.
383 if (osthread() != NULL) os::free_thread(osthread());
384
385 // clear Thread::current if thread is deleting itself.
386 // Needed to ensure JNI correctly detects non-attached threads.
387 if (this == Thread::current()) {
388 clear_thread_current();
389 }
390
391 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
392 }
393
394 // NOTE: dummy function for assertion purpose.
395 void Thread::run() {
396 ShouldNotReachHere();
397 }
398
399 #ifdef ASSERT
400 // Private method to check for dangling thread pointer
401 void check_for_dangling_thread_pointer(Thread *thread) {
402 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
403 "possibility of dangling Thread pointer");
404 }
405 #endif
406
407 ThreadPriority Thread::get_priority(const Thread* const thread) {
408 ThreadPriority priority;
409 // Can return an error!
410 (void)os::get_priority(thread, priority);
411 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
412 return priority;
413 }
414
415 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
416 debug_only(check_for_dangling_thread_pointer(thread);)
417 // Can return an error!
418 (void)os::set_priority(thread, priority);
419 }
420
421
422 void Thread::start(Thread* thread) {
423 // Start is different from resume in that its safety is guaranteed by context or
424 // being called from a Java method synchronized on the Thread object.
425 if (!DisableStartThread) {
426 if (thread->is_Java_thread()) {
427 // Initialize the thread state to RUNNABLE before starting this thread.
428 // Can not set it after the thread started because we do not know the
429 // exact thread state at that time. It could be in MONITOR_WAIT or
430 // in SLEEPING or some other state.
431 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
432 java_lang_Thread::RUNNABLE);
433 }
434 os::start_thread(thread);
435 }
436 }
437
438 // Enqueue a VM_Operation to do the job for us - sometime later
439 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
440 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
441 VMThread::execute(vm_stop);
442 }
443
444
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469
470 // Helper class for tracing suspend wait debug bits.
471 //
472 // 0x00000100 indicates that the target thread exited before it could
473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
474 // 0x00080000 each indicate a cancelled suspend request so they don't
475 // count as wait failures either.
476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
477
478 class TraceSuspendDebugBits : public StackObj {
479 private:
480 JavaThread * jt;
481 bool is_wait;
482 bool called_by_wait; // meaningful when !is_wait
483 uint32_t * bits;
484
485 public:
486 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
487 uint32_t *_bits) {
488 jt = _jt;
489 is_wait = _is_wait;
490 called_by_wait = _called_by_wait;
491 bits = _bits;
492 }
493
494 ~TraceSuspendDebugBits() {
495 if (!is_wait) {
496 #if 1
497 // By default, don't trace bits for is_ext_suspend_completed() calls.
498 // That trace is very chatty.
499 return;
500 #else
501 if (!called_by_wait) {
502 // If tracing for is_ext_suspend_completed() is enabled, then only
503 // trace calls to it from wait_for_ext_suspend_completion()
504 return;
505 }
506 #endif
507 }
508
509 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
510 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
511 MutexLocker ml(Threads_lock); // needed for get_thread_name()
512 ResourceMark rm;
513
514 tty->print_cr(
515 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
516 jt->get_thread_name(), *bits);
517
518 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
519 }
520 }
521 }
522 };
523 #undef DEBUG_FALSE_BITS
524
525
526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
527 uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
529
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
532
533 *bits |= 0x00000001;
534
535 do {
536 do_trans_retry = false;
537
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
544
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
552
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
558
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
571
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
608
609 *bits |= 0x00004000;
610
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
616
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
625
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
630
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
639
640
641 }
642 } while (do_trans_retry);
643
644 *bits |= 0x00000010;
645 return false;
646 }
647
648 // Wait for an external suspend request to complete (or be cancelled).
649 // Returns true if the thread is externally suspended and false otherwise.
650 //
651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
652 uint32_t *bits) {
653 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
654 false /* !called_by_wait */, bits);
655
656 // local flag copies to minimize SR_lock hold time
657 bool is_suspended;
658 bool pending;
659 uint32_t reset_bits;
660
661 // set a marker so is_ext_suspend_completed() knows we are the caller
662 *bits |= 0x00010000;
663
664 // We use reset_bits to reinitialize the bits value at the top of
665 // each retry loop. This allows the caller to make use of any
666 // unused bits for their own marking purposes.
667 reset_bits = *bits;
668
669 {
670 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
671 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
672 delay, bits);
673 pending = is_external_suspend();
674 }
675 // must release SR_lock to allow suspension to complete
676
677 if (!pending) {
678 // A cancelled suspend request is the only false return from
679 // is_ext_suspend_completed() that keeps us from entering the
680 // retry loop.
681 *bits |= 0x00020000;
682 return false;
683 }
684
685 if (is_suspended) {
686 *bits |= 0x00040000;
687 return true;
688 }
689
690 for (int i = 1; i <= retries; i++) {
691 *bits = reset_bits; // reinit to only track last retry
692
693 // We used to do an "os::yield_all(i)" call here with the intention
694 // that yielding would increase on each retry. However, the parameter
695 // is ignored on Linux which means the yield didn't scale up. Waiting
696 // on the SR_lock below provides a much more predictable scale up for
697 // the delay. It also provides a simple/direct point to check for any
698 // safepoint requests from the VMThread
699
700 {
701 MutexLocker ml(SR_lock());
702 // wait with safepoint check (if we're a JavaThread - the WatcherThread
703 // can also call this) and increase delay with each retry
704 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
705
706 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
707 delay, bits);
708
709 // It is possible for the external suspend request to be cancelled
710 // (by a resume) before the actual suspend operation is completed.
711 // Refresh our local copy to see if we still need to wait.
712 pending = is_external_suspend();
713 }
714
715 if (!pending) {
716 // A cancelled suspend request is the only false return from
717 // is_ext_suspend_completed() that keeps us from staying in the
718 // retry loop.
719 *bits |= 0x00080000;
720 return false;
721 }
722
723 if (is_suspended) {
724 *bits |= 0x00100000;
725 return true;
726 }
727 } // end retry loop
728
729 // thread did not suspend after all our retries
730 *bits |= 0x00200000;
731 return false;
732 }
733
734 #ifndef PRODUCT
735 void JavaThread::record_jump(address target, address instr, const char* file,
736 int line) {
737
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existent
740 // and we don't care that much anyway.
741
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif // PRODUCT
750
751 // Called by flat profiler
752 // Callers have already called wait_for_ext_suspend_completion
753 // The assertion for that is currently too complex to put here:
754 bool JavaThread::profile_last_Java_frame(frame* _fr) {
755 bool gotframe = false;
756 // self suspension saves needed state.
757 if (has_last_Java_frame() && _anchor.walkable()) {
758 *_fr = pd_last_frame();
759 gotframe = true;
760 }
761 return gotframe;
762 }
763
764 void Thread::interrupt(Thread* thread) {
765 debug_only(check_for_dangling_thread_pointer(thread);)
766 os::interrupt(thread);
767 }
768
769 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
770 debug_only(check_for_dangling_thread_pointer(thread);)
771 // Note: If clear_interrupted==false, this simply fetches and
772 // returns the value of the field osthread()->interrupted().
773 return os::is_interrupted(thread, clear_interrupted);
774 }
775
776
777 // GC Support
778 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
779 jint thread_parity = _oops_do_parity;
780 if (thread_parity != strong_roots_parity) {
781 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
782 if (res == thread_parity) {
783 return true;
784 } else {
785 guarantee(res == strong_roots_parity, "Or else what?");
786 return false;
787 }
788 }
789 return false;
790 }
791
792 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
793 active_handles()->oops_do(f);
794 // Do oop for ThreadShadow
795 f->do_oop((oop*)&_pending_exception);
796 handle_area()->oops_do(f);
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 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
826
827 if (is_VM_thread()) { st->print("VMThread"); }
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 if (is_Named_thread()) {
834 st->print(" \"%s\"", name());
835 }
836
837 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
838 p2i(stack_end()), p2i(stack_base()));
839
840 if (osthread()) {
841 st->print(" [id=%d]", osthread()->thread_id());
842 }
843 }
844
845 #ifdef ASSERT
846 void Thread::print_owned_locks_on(outputStream* st) const {
847 Monitor *cur = _owned_locks;
848 if (cur == NULL) {
849 st->print(" (no locks) ");
850 } else {
851 st->print_cr(" Locks owned:");
852 while (cur) {
853 cur->print_on(st);
854 cur = cur->next();
855 }
856 }
857 }
858
859 static int ref_use_count = 0;
860
861 bool Thread::owns_locks_but_compiled_lock() const {
862 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
863 if (cur != Compile_lock) return true;
864 }
865 return false;
866 }
867
868
869 #endif
870
871 #ifndef PRODUCT
872
873 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
874 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
875 // no threads which allow_vm_block's are held
876 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
877 // Check if current thread is allowed to block at a safepoint
878 if (!(_allow_safepoint_count == 0)) {
879 fatal("Possible safepoint reached by thread that does not allow it");
880 }
881 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
882 fatal("LEAF method calling lock?");
883 }
884
885 #ifdef ASSERT
886 if (potential_vm_operation && is_Java_thread()
887 && !Universe::is_bootstrapping()) {
888 // Make sure we do not hold any locks that the VM thread also uses.
889 // This could potentially lead to deadlocks
890 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
891 // Threads_lock is special, since the safepoint synchronization will not start before this is
892 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
893 // since it is used to transfer control between JavaThreads and the VMThread
894 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
895 if ((cur->allow_vm_block() &&
896 cur != Threads_lock &&
897 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
898 cur != VMOperationRequest_lock &&
899 cur != VMOperationQueue_lock) ||
900 cur->rank() == Mutex::special) {
901 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
902 }
903 }
904 }
905
906 if (GCALotAtAllSafepoints) {
907 // We could enter a safepoint here and thus have a gc
908 InterfaceSupport::check_gc_alot();
909 }
910 #endif
911 }
912 #endif
913
914 bool Thread::is_in_stack(address adr) const {
915 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
916 address end = os::current_stack_pointer();
917 // Allow non Java threads to call this without stack_base
918 if (_stack_base == NULL) return true;
919 if (stack_base() >= adr && adr >= end) return true;
920
921 return false;
922 }
923
924 bool Thread::is_in_usable_stack(address adr) const {
925 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
926 size_t usable_stack_size = _stack_size - stack_guard_size;
927
928 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
929 }
930
931
932 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
933 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
934 // used for compilation in the future. If that change is made, the need for these methods
935 // should be revisited, and they should be removed if possible.
936
937 bool Thread::is_lock_owned(address adr) const {
938 return on_local_stack(adr);
939 }
940
941 bool Thread::set_as_starting_thread() {
942 // NOTE: this must be called inside the main thread.
943 return os::create_main_thread((JavaThread*)this);
944 }
945
946 static void initialize_class(Symbol* class_name, TRAPS) {
947 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
948 InstanceKlass::cast(klass)->initialize(CHECK);
949 }
950
951
952 // Creates the initial ThreadGroup
953 static Handle create_initial_thread_group(TRAPS) {
954 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
955 instanceKlassHandle klass (THREAD, k);
956
957 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
958 {
959 JavaValue result(T_VOID);
960 JavaCalls::call_special(&result,
961 system_instance,
962 klass,
963 vmSymbols::object_initializer_name(),
964 vmSymbols::void_method_signature(),
965 CHECK_NH);
966 }
967 Universe::set_system_thread_group(system_instance());
968
969 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
970 {
971 JavaValue result(T_VOID);
972 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
973 JavaCalls::call_special(&result,
974 main_instance,
975 klass,
976 vmSymbols::object_initializer_name(),
977 vmSymbols::threadgroup_string_void_signature(),
978 system_instance,
979 string,
980 CHECK_NH);
981 }
982 return main_instance;
983 }
984
985 // Creates the initial Thread
986 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
987 TRAPS) {
988 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
989 instanceKlassHandle klass (THREAD, k);
990 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
991
992 java_lang_Thread::set_thread(thread_oop(), thread);
993 java_lang_Thread::set_priority(thread_oop(), NormPriority);
994 thread->set_threadObj(thread_oop());
995
996 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
997
998 JavaValue result(T_VOID);
999 JavaCalls::call_special(&result, thread_oop,
1000 klass,
1001 vmSymbols::object_initializer_name(),
1002 vmSymbols::threadgroup_string_void_signature(),
1003 thread_group,
1004 string,
1005 CHECK_NULL);
1006 return thread_oop();
1007 }
1008
1009 char java_runtime_name[128] = "";
1010 char java_runtime_version[128] = "";
1011
1012 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1013 static const char* get_java_runtime_name(TRAPS) {
1014 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1015 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1016 fieldDescriptor fd;
1017 bool found = k != NULL &&
1018 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1019 vmSymbols::string_signature(), &fd);
1020 if (found) {
1021 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1022 if (name_oop == NULL) {
1023 return NULL;
1024 }
1025 const char* name = java_lang_String::as_utf8_string(name_oop,
1026 java_runtime_name,
1027 sizeof(java_runtime_name));
1028 return name;
1029 } else {
1030 return NULL;
1031 }
1032 }
1033
1034 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1035 static const char* get_java_runtime_version(TRAPS) {
1036 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1037 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1038 fieldDescriptor fd;
1039 bool found = k != NULL &&
1040 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1041 vmSymbols::string_signature(), &fd);
1042 if (found) {
1043 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1044 if (name_oop == NULL) {
1045 return NULL;
1046 }
1047 const char* name = java_lang_String::as_utf8_string(name_oop,
1048 java_runtime_version,
1049 sizeof(java_runtime_version));
1050 return name;
1051 } else {
1052 return NULL;
1053 }
1054 }
1055
1056 // General purpose hook into Java code, run once when the VM is initialized.
1057 // The Java library method itself may be changed independently from the VM.
1058 static void call_postVMInitHook(TRAPS) {
1059 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1060 instanceKlassHandle klass (THREAD, k);
1061 if (klass.not_null()) {
1062 JavaValue result(T_VOID);
1063 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1064 vmSymbols::void_method_signature(),
1065 CHECK);
1066 }
1067 }
1068
1069 static void reset_vm_info_property(TRAPS) {
1070 // the vm info string
1071 ResourceMark rm(THREAD);
1072 const char *vm_info = VM_Version::vm_info_string();
1073
1074 // java.lang.System class
1075 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1076 instanceKlassHandle klass (THREAD, k);
1077
1078 // setProperty arguments
1079 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1080 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1081
1082 // return value
1083 JavaValue r(T_OBJECT);
1084
1085 // public static String setProperty(String key, String value);
1086 JavaCalls::call_static(&r,
1087 klass,
1088 vmSymbols::setProperty_name(),
1089 vmSymbols::string_string_string_signature(),
1090 key_str,
1091 value_str,
1092 CHECK);
1093 }
1094
1095
1096 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1097 bool daemon, TRAPS) {
1098 assert(thread_group.not_null(), "thread group should be specified");
1099 assert(threadObj() == NULL, "should only create Java thread object once");
1100
1101 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1102 instanceKlassHandle klass (THREAD, k);
1103 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1104
1105 java_lang_Thread::set_thread(thread_oop(), this);
1106 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1107 set_threadObj(thread_oop());
1108
1109 JavaValue result(T_VOID);
1110 if (thread_name != NULL) {
1111 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1112 // Thread gets assigned specified name and null target
1113 JavaCalls::call_special(&result,
1114 thread_oop,
1115 klass,
1116 vmSymbols::object_initializer_name(),
1117 vmSymbols::threadgroup_string_void_signature(),
1118 thread_group, // Argument 1
1119 name, // Argument 2
1120 THREAD);
1121 } else {
1122 // Thread gets assigned name "Thread-nnn" and null target
1123 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1124 JavaCalls::call_special(&result,
1125 thread_oop,
1126 klass,
1127 vmSymbols::object_initializer_name(),
1128 vmSymbols::threadgroup_runnable_void_signature(),
1129 thread_group, // Argument 1
1130 Handle(), // Argument 2
1131 THREAD);
1132 }
1133
1134
1135 if (daemon) {
1136 java_lang_Thread::set_daemon(thread_oop());
1137 }
1138
1139 if (HAS_PENDING_EXCEPTION) {
1140 return;
1141 }
1142
1143 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1144 Handle threadObj(THREAD, this->threadObj());
1145
1146 JavaCalls::call_special(&result,
1147 thread_group,
1148 group,
1149 vmSymbols::add_method_name(),
1150 vmSymbols::thread_void_signature(),
1151 threadObj, // Arg 1
1152 THREAD);
1153 }
1154
1155 // NamedThread -- non-JavaThread subclasses with multiple
1156 // uniquely named instances should derive from this.
1157 NamedThread::NamedThread() : Thread() {
1158 _name = NULL;
1159 _processed_thread = NULL;
1160 _gc_id = GCId::undefined();
1161 }
1162
1163 NamedThread::~NamedThread() {
1164 if (_name != NULL) {
1165 FREE_C_HEAP_ARRAY(char, _name);
1166 _name = NULL;
1167 }
1168 }
1169
1170 void NamedThread::set_name(const char* format, ...) {
1171 guarantee(_name == NULL, "Only get to set name once.");
1172 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1173 guarantee(_name != NULL, "alloc failure");
1174 va_list ap;
1175 va_start(ap, format);
1176 jio_vsnprintf(_name, max_name_len, format, ap);
1177 va_end(ap);
1178 }
1179
1180 void NamedThread::initialize_named_thread() {
1181 set_native_thread_name(name());
1182 }
1183
1184 void NamedThread::print_on(outputStream* st) const {
1185 st->print("\"%s\" ", name());
1186 Thread::print_on(st);
1187 st->cr();
1188 }
1189
1190
1191 // ======= WatcherThread ========
1192
1193 // The watcher thread exists to simulate timer interrupts. It should
1194 // be replaced by an abstraction over whatever native support for
1195 // timer interrupts exists on the platform.
1196
1197 WatcherThread* WatcherThread::_watcher_thread = NULL;
1198 bool WatcherThread::_startable = false;
1199 volatile bool WatcherThread::_should_terminate = false;
1200
1201 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1202 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1203 if (os::create_thread(this, os::watcher_thread)) {
1204 _watcher_thread = this;
1205
1206 // Set the watcher thread to the highest OS priority which should not be
1207 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1208 // is created. The only normal thread using this priority is the reference
1209 // handler thread, which runs for very short intervals only.
1210 // If the VMThread's priority is not lower than the WatcherThread profiling
1211 // will be inaccurate.
1212 os::set_priority(this, MaxPriority);
1213 if (!DisableStartThread) {
1214 os::start_thread(this);
1215 }
1216 }
1217 }
1218
1219 int WatcherThread::sleep() const {
1220 // The WatcherThread does not participate in the safepoint protocol
1221 // for the PeriodicTask_lock because it is not a JavaThread.
1222 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1223
1224 if (_should_terminate) {
1225 // check for termination before we do any housekeeping or wait
1226 return 0; // we did not sleep.
1227 }
1228
1229 // remaining will be zero if there are no tasks,
1230 // causing the WatcherThread to sleep until a task is
1231 // enrolled
1232 int remaining = PeriodicTask::time_to_wait();
1233 int time_slept = 0;
1234
1235 // we expect this to timeout - we only ever get unparked when
1236 // we should terminate or when a new task has been enrolled
1237 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1238
1239 jlong time_before_loop = os::javaTimeNanos();
1240
1241 while (true) {
1242 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1243 remaining);
1244 jlong now = os::javaTimeNanos();
1245
1246 if (remaining == 0) {
1247 // if we didn't have any tasks we could have waited for a long time
1248 // consider the time_slept zero and reset time_before_loop
1249 time_slept = 0;
1250 time_before_loop = now;
1251 } else {
1252 // need to recalculate since we might have new tasks in _tasks
1253 time_slept = (int) ((now - time_before_loop) / 1000000);
1254 }
1255
1256 // Change to task list or spurious wakeup of some kind
1257 if (timedout || _should_terminate) {
1258 break;
1259 }
1260
1261 remaining = PeriodicTask::time_to_wait();
1262 if (remaining == 0) {
1263 // Last task was just disenrolled so loop around and wait until
1264 // another task gets enrolled
1265 continue;
1266 }
1267
1268 remaining -= time_slept;
1269 if (remaining <= 0) {
1270 break;
1271 }
1272 }
1273
1274 return time_slept;
1275 }
1276
1277 void WatcherThread::run() {
1278 assert(this == watcher_thread(), "just checking");
1279
1280 this->record_stack_base_and_size();
1281 this->set_native_thread_name(this->name());
1282 this->set_active_handles(JNIHandleBlock::allocate_block());
1283 while (true) {
1284 assert(watcher_thread() == Thread::current(), "thread consistency check");
1285 assert(watcher_thread() == this, "thread consistency check");
1286
1287 // Calculate how long it'll be until the next PeriodicTask work
1288 // should be done, and sleep that amount of time.
1289 int time_waited = sleep();
1290
1291 if (is_error_reported()) {
1292 // A fatal error has happened, the error handler(VMError::report_and_die)
1293 // should abort JVM after creating an error log file. However in some
1294 // rare cases, the error handler itself might deadlock. Here we try to
1295 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1296 //
1297 // This code is in WatcherThread because WatcherThread wakes up
1298 // periodically so the fatal error handler doesn't need to do anything;
1299 // also because the WatcherThread is less likely to crash than other
1300 // threads.
1301
1302 for (;;) {
1303 if (!ShowMessageBoxOnError
1304 && (OnError == NULL || OnError[0] == '\0')
1305 && Arguments::abort_hook() == NULL) {
1306 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1307 fdStream err(defaultStream::output_fd());
1308 err.print_raw_cr("# [ timer expired, abort... ]");
1309 // skip atexit/vm_exit/vm_abort hooks
1310 os::die();
1311 }
1312
1313 // Wake up 5 seconds later, the fatal handler may reset OnError or
1314 // ShowMessageBoxOnError when it is ready to abort.
1315 os::sleep(this, 5 * 1000, false);
1316 }
1317 }
1318
1319 if (_should_terminate) {
1320 // check for termination before posting the next tick
1321 break;
1322 }
1323
1324 PeriodicTask::real_time_tick(time_waited);
1325 }
1326
1327 // Signal that it is terminated
1328 {
1329 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1330 _watcher_thread = NULL;
1331 Terminator_lock->notify();
1332 }
1333 }
1334
1335 void WatcherThread::start() {
1336 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1337
1338 if (watcher_thread() == NULL && _startable) {
1339 _should_terminate = false;
1340 // Create the single instance of WatcherThread
1341 new WatcherThread();
1342 }
1343 }
1344
1345 void WatcherThread::make_startable() {
1346 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1347 _startable = true;
1348 }
1349
1350 void WatcherThread::stop() {
1351 {
1352 // Follow normal safepoint aware lock enter protocol since the
1353 // WatcherThread is stopped by another JavaThread.
1354 MutexLocker ml(PeriodicTask_lock);
1355 _should_terminate = true;
1356
1357 WatcherThread* watcher = watcher_thread();
1358 if (watcher != NULL) {
1359 // unpark the WatcherThread so it can see that it should terminate
1360 watcher->unpark();
1361 }
1362 }
1363
1364 MutexLocker mu(Terminator_lock);
1365
1366 while (watcher_thread() != NULL) {
1367 // This wait should make safepoint checks, wait without a timeout,
1368 // and wait as a suspend-equivalent condition.
1369 //
1370 // Note: If the FlatProfiler is running, then this thread is waiting
1371 // for the WatcherThread to terminate and the WatcherThread, via the
1372 // FlatProfiler task, is waiting for the external suspend request on
1373 // this thread to complete. wait_for_ext_suspend_completion() will
1374 // eventually timeout, but that takes time. Making this wait a
1375 // suspend-equivalent condition solves that timeout problem.
1376 //
1377 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1378 Mutex::_as_suspend_equivalent_flag);
1379 }
1380 }
1381
1382 void WatcherThread::unpark() {
1383 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1384 PeriodicTask_lock->notify();
1385 }
1386
1387 void WatcherThread::print_on(outputStream* st) const {
1388 st->print("\"%s\" ", name());
1389 Thread::print_on(st);
1390 st->cr();
1391 }
1392
1393 // ======= JavaThread ========
1394
1395 #if INCLUDE_JVMCI
1396
1397 jlong* JavaThread::_jvmci_old_thread_counters;
1398
1399 bool jvmci_counters_include(JavaThread* thread) {
1400 oop threadObj = thread->threadObj();
1401 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1402 }
1403
1404 void JavaThread::collect_counters(typeArrayOop array) {
1405 if (JVMCICounterSize > 0) {
1406 MutexLocker tl(Threads_lock);
1407 for (int i = 0; i < array->length(); i++) {
1408 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1409 }
1410 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1411 if (jvmci_counters_include(tp)) {
1412 for (int i = 0; i < array->length(); i++) {
1413 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1414 }
1415 }
1416 }
1417 }
1418 }
1419
1420 #endif // INCLUDE_JVMCI
1421
1422 // A JavaThread is a normal Java thread
1423
1424 void JavaThread::initialize() {
1425 // Initialize fields
1426
1427 set_saved_exception_pc(NULL);
1428 set_threadObj(NULL);
1429 _anchor.clear();
1430 set_entry_point(NULL);
1431 set_jni_functions(jni_functions());
1432 set_callee_target(NULL);
1433 set_vm_result(NULL);
1434 set_vm_result_2(NULL);
1435 set_vframe_array_head(NULL);
1436 set_vframe_array_last(NULL);
1437 set_deferred_locals(NULL);
1438 set_deopt_mark(NULL);
1439 set_deopt_compiled_method(NULL);
1440 clear_must_deopt_id();
1441 set_monitor_chunks(NULL);
1442 set_next(NULL);
1443 set_thread_state(_thread_new);
1444 _terminated = _not_terminated;
1445 _privileged_stack_top = NULL;
1446 _array_for_gc = NULL;
1447 _suspend_equivalent = false;
1448 _in_deopt_handler = 0;
1449 _doing_unsafe_access = false;
1450 _stack_guard_state = stack_guard_unused;
1451 #if INCLUDE_JVMCI
1452 _pending_monitorenter = false;
1453 _pending_deoptimization = -1;
1454 _pending_failed_speculation = NULL;
1455 _pending_transfer_to_interpreter = false;
1456 _adjusting_comp_level = false;
1457 _jvmci._alternate_call_target = NULL;
1458 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1459 if (JVMCICounterSize > 0) {
1460 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1461 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1462 } else {
1463 _jvmci_counters = NULL;
1464 }
1465 #endif // INCLUDE_JVMCI
1466 _reserved_stack_activation = NULL; // stack base not known yet
1467 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1468 _exception_pc = 0;
1469 _exception_handler_pc = 0;
1470 _is_method_handle_return = 0;
1471 _jvmti_thread_state= NULL;
1472 _should_post_on_exceptions_flag = JNI_FALSE;
1473 _jvmti_get_loaded_classes_closure = NULL;
1474 _interp_only_mode = 0;
1475 _special_runtime_exit_condition = _no_async_condition;
1476 _pending_async_exception = NULL;
1477 _thread_stat = NULL;
1478 _thread_stat = new ThreadStatistics();
1479 _blocked_on_compilation = false;
1480 _jni_active_critical = 0;
1481 _pending_jni_exception_check_fn = NULL;
1482 _do_not_unlock_if_synchronized = false;
1483 _cached_monitor_info = NULL;
1484 _parker = Parker::Allocate(this);
1485
1486 #ifndef PRODUCT
1487 _jmp_ring_index = 0;
1488 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1489 record_jump(NULL, NULL, NULL, 0);
1490 }
1491 #endif // PRODUCT
1492
1493 set_thread_profiler(NULL);
1494 if (FlatProfiler::is_active()) {
1495 // This is where we would decide to either give each thread it's own profiler
1496 // or use one global one from FlatProfiler,
1497 // or up to some count of the number of profiled threads, etc.
1498 ThreadProfiler* pp = new ThreadProfiler();
1499 pp->engage();
1500 set_thread_profiler(pp);
1501 }
1502
1503 // Setup safepoint state info for this thread
1504 ThreadSafepointState::create(this);
1505
1506 debug_only(_java_call_counter = 0);
1507
1508 // JVMTI PopFrame support
1509 _popframe_condition = popframe_inactive;
1510 _popframe_preserved_args = NULL;
1511 _popframe_preserved_args_size = 0;
1512 _frames_to_pop_failed_realloc = 0;
1513
1514 pd_initialize();
1515 }
1516
1517 #if INCLUDE_ALL_GCS
1518 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1519 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1520 #endif // INCLUDE_ALL_GCS
1521
1522 JavaThread::JavaThread(bool is_attaching_via_jni) :
1523 Thread()
1524 #if INCLUDE_ALL_GCS
1525 , _satb_mark_queue(&_satb_mark_queue_set),
1526 _dirty_card_queue(&_dirty_card_queue_set)
1527 #endif // INCLUDE_ALL_GCS
1528 {
1529 initialize();
1530 if (is_attaching_via_jni) {
1531 _jni_attach_state = _attaching_via_jni;
1532 } else {
1533 _jni_attach_state = _not_attaching_via_jni;
1534 }
1535 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1536 }
1537
1538 bool JavaThread::reguard_stack(address cur_sp) {
1539 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1540 && _stack_guard_state != stack_guard_reserved_disabled) {
1541 return true; // Stack already guarded or guard pages not needed.
1542 }
1543
1544 if (register_stack_overflow()) {
1545 // For those architectures which have separate register and
1546 // memory stacks, we must check the register stack to see if
1547 // it has overflowed.
1548 return false;
1549 }
1550
1551 // Java code never executes within the yellow zone: the latter is only
1552 // there to provoke an exception during stack banging. If java code
1553 // is executing there, either StackShadowPages should be larger, or
1554 // some exception code in c1, c2 or the interpreter isn't unwinding
1555 // when it should.
1556 guarantee(cur_sp > stack_reserved_zone_base(),
1557 "not enough space to reguard - increase StackShadowPages");
1558 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1559 enable_stack_yellow_reserved_zone();
1560 if (reserved_stack_activation() != stack_base()) {
1561 set_reserved_stack_activation(stack_base());
1562 }
1563 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1564 set_reserved_stack_activation(stack_base());
1565 enable_stack_reserved_zone();
1566 }
1567 return true;
1568 }
1569
1570 bool JavaThread::reguard_stack(void) {
1571 return reguard_stack(os::current_stack_pointer());
1572 }
1573
1574
1575 void JavaThread::block_if_vm_exited() {
1576 if (_terminated == _vm_exited) {
1577 // _vm_exited is set at safepoint, and Threads_lock is never released
1578 // we will block here forever
1579 Threads_lock->lock_without_safepoint_check();
1580 ShouldNotReachHere();
1581 }
1582 }
1583
1584
1585 // Remove this ifdef when C1 is ported to the compiler interface.
1586 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1587 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1588
1589 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1590 Thread()
1591 #if INCLUDE_ALL_GCS
1592 , _satb_mark_queue(&_satb_mark_queue_set),
1593 _dirty_card_queue(&_dirty_card_queue_set)
1594 #endif // INCLUDE_ALL_GCS
1595 {
1596 initialize();
1597 _jni_attach_state = _not_attaching_via_jni;
1598 set_entry_point(entry_point);
1599 // Create the native thread itself.
1600 // %note runtime_23
1601 os::ThreadType thr_type = os::java_thread;
1602 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1603 os::java_thread;
1604 os::create_thread(this, thr_type, stack_sz);
1605 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1606 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1607 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1608 // the exception consists of creating the exception object & initializing it, initialization
1609 // will leave the VM via a JavaCall and then all locks must be unlocked).
1610 //
1611 // The thread is still suspended when we reach here. Thread must be explicit started
1612 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1613 // by calling Threads:add. The reason why this is not done here, is because the thread
1614 // object must be fully initialized (take a look at JVM_Start)
1615 }
1616
1617 JavaThread::~JavaThread() {
1618
1619 // JSR166 -- return the parker to the free list
1620 Parker::Release(_parker);
1621 _parker = NULL;
1622
1623 // Free any remaining previous UnrollBlock
1624 vframeArray* old_array = vframe_array_last();
1625
1626 if (old_array != NULL) {
1627 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1628 old_array->set_unroll_block(NULL);
1629 delete old_info;
1630 delete old_array;
1631 }
1632
1633 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1634 if (deferred != NULL) {
1635 // This can only happen if thread is destroyed before deoptimization occurs.
1636 assert(deferred->length() != 0, "empty array!");
1637 do {
1638 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1639 deferred->remove_at(0);
1640 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1641 delete dlv;
1642 } while (deferred->length() != 0);
1643 delete deferred;
1644 }
1645
1646 // All Java related clean up happens in exit
1647 ThreadSafepointState::destroy(this);
1648 if (_thread_profiler != NULL) delete _thread_profiler;
1649 if (_thread_stat != NULL) delete _thread_stat;
1650
1651 #if INCLUDE_JVMCI
1652 if (JVMCICounterSize > 0) {
1653 if (jvmci_counters_include(this)) {
1654 for (int i = 0; i < JVMCICounterSize; i++) {
1655 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1656 }
1657 }
1658 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1659 }
1660 #endif // INCLUDE_JVMCI
1661 }
1662
1663
1664 // The first routine called by a new Java thread
1665 void JavaThread::run() {
1666 // initialize thread-local alloc buffer related fields
1667 this->initialize_tlab();
1668
1669 // used to test validity of stack trace backs
1670 this->record_base_of_stack_pointer();
1671
1672 // Record real stack base and size.
1673 this->record_stack_base_and_size();
1674
1675 this->create_stack_guard_pages();
1676
1677 this->cache_global_variables();
1678
1679 // Thread is now sufficient initialized to be handled by the safepoint code as being
1680 // in the VM. Change thread state from _thread_new to _thread_in_vm
1681 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1682
1683 assert(JavaThread::current() == this, "sanity check");
1684 assert(!Thread::current()->owns_locks(), "sanity check");
1685
1686 DTRACE_THREAD_PROBE(start, this);
1687
1688 // This operation might block. We call that after all safepoint checks for a new thread has
1689 // been completed.
1690 this->set_active_handles(JNIHandleBlock::allocate_block());
1691
1692 if (JvmtiExport::should_post_thread_life()) {
1693 JvmtiExport::post_thread_start(this);
1694 }
1695
1696 EventThreadStart event;
1697 if (event.should_commit()) {
1698 event.set_thread(THREAD_TRACE_ID(this));
1699 event.commit();
1700 }
1701
1702 // We call another function to do the rest so we are sure that the stack addresses used
1703 // from there will be lower than the stack base just computed
1704 thread_main_inner();
1705
1706 // Note, thread is no longer valid at this point!
1707 }
1708
1709
1710 void JavaThread::thread_main_inner() {
1711 assert(JavaThread::current() == this, "sanity check");
1712 assert(this->threadObj() != NULL, "just checking");
1713
1714 // Execute thread entry point unless this thread has a pending exception
1715 // or has been stopped before starting.
1716 // Note: Due to JVM_StopThread we can have pending exceptions already!
1717 if (!this->has_pending_exception() &&
1718 !java_lang_Thread::is_stillborn(this->threadObj())) {
1719 {
1720 ResourceMark rm(this);
1721 this->set_native_thread_name(this->get_thread_name());
1722 }
1723 HandleMark hm(this);
1724 this->entry_point()(this, this);
1725 }
1726
1727 DTRACE_THREAD_PROBE(stop, this);
1728
1729 this->exit(false);
1730 delete this;
1731 }
1732
1733
1734 static void ensure_join(JavaThread* thread) {
1735 // We do not need to grap the Threads_lock, since we are operating on ourself.
1736 Handle threadObj(thread, thread->threadObj());
1737 assert(threadObj.not_null(), "java thread object must exist");
1738 ObjectLocker lock(threadObj, thread);
1739 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1740 thread->clear_pending_exception();
1741 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1742 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1743 // Clear the native thread instance - this makes isAlive return false and allows the join()
1744 // to complete once we've done the notify_all below
1745 java_lang_Thread::set_thread(threadObj(), NULL);
1746 lock.notify_all(thread);
1747 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1748 thread->clear_pending_exception();
1749 }
1750
1751
1752 // For any new cleanup additions, please check to see if they need to be applied to
1753 // cleanup_failed_attach_current_thread as well.
1754 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1755 assert(this == JavaThread::current(), "thread consistency check");
1756
1757 HandleMark hm(this);
1758 Handle uncaught_exception(this, this->pending_exception());
1759 this->clear_pending_exception();
1760 Handle threadObj(this, this->threadObj());
1761 assert(threadObj.not_null(), "Java thread object should be created");
1762
1763 if (get_thread_profiler() != NULL) {
1764 get_thread_profiler()->disengage();
1765 ResourceMark rm;
1766 get_thread_profiler()->print(get_thread_name());
1767 }
1768
1769
1770 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1771 {
1772 EXCEPTION_MARK;
1773
1774 CLEAR_PENDING_EXCEPTION;
1775 }
1776 if (!destroy_vm) {
1777 if (uncaught_exception.not_null()) {
1778 EXCEPTION_MARK;
1779 // Call method Thread.dispatchUncaughtException().
1780 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1781 JavaValue result(T_VOID);
1782 JavaCalls::call_virtual(&result,
1783 threadObj, thread_klass,
1784 vmSymbols::dispatchUncaughtException_name(),
1785 vmSymbols::throwable_void_signature(),
1786 uncaught_exception,
1787 THREAD);
1788 if (HAS_PENDING_EXCEPTION) {
1789 ResourceMark rm(this);
1790 jio_fprintf(defaultStream::error_stream(),
1791 "\nException: %s thrown from the UncaughtExceptionHandler"
1792 " in thread \"%s\"\n",
1793 pending_exception()->klass()->external_name(),
1794 get_thread_name());
1795 CLEAR_PENDING_EXCEPTION;
1796 }
1797 }
1798
1799 // Called before the java thread exit since we want to read info
1800 // from java_lang_Thread object
1801 EventThreadEnd event;
1802 if (event.should_commit()) {
1803 event.set_thread(THREAD_TRACE_ID(this));
1804 event.commit();
1805 }
1806
1807 // Call after last event on thread
1808 EVENT_THREAD_EXIT(this);
1809
1810 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1811 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1812 // is deprecated anyhow.
1813 if (!is_Compiler_thread()) {
1814 int count = 3;
1815 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1816 EXCEPTION_MARK;
1817 JavaValue result(T_VOID);
1818 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1819 JavaCalls::call_virtual(&result,
1820 threadObj, thread_klass,
1821 vmSymbols::exit_method_name(),
1822 vmSymbols::void_method_signature(),
1823 THREAD);
1824 CLEAR_PENDING_EXCEPTION;
1825 }
1826 }
1827 // notify JVMTI
1828 if (JvmtiExport::should_post_thread_life()) {
1829 JvmtiExport::post_thread_end(this);
1830 }
1831
1832 // We have notified the agents that we are exiting, before we go on,
1833 // we must check for a pending external suspend request and honor it
1834 // in order to not surprise the thread that made the suspend request.
1835 while (true) {
1836 {
1837 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1838 if (!is_external_suspend()) {
1839 set_terminated(_thread_exiting);
1840 ThreadService::current_thread_exiting(this);
1841 break;
1842 }
1843 // Implied else:
1844 // Things get a little tricky here. We have a pending external
1845 // suspend request, but we are holding the SR_lock so we
1846 // can't just self-suspend. So we temporarily drop the lock
1847 // and then self-suspend.
1848 }
1849
1850 ThreadBlockInVM tbivm(this);
1851 java_suspend_self();
1852
1853 // We're done with this suspend request, but we have to loop around
1854 // and check again. Eventually we will get SR_lock without a pending
1855 // external suspend request and will be able to mark ourselves as
1856 // exiting.
1857 }
1858 // no more external suspends are allowed at this point
1859 } else {
1860 // before_exit() has already posted JVMTI THREAD_END events
1861 }
1862
1863 // Notify waiters on thread object. This has to be done after exit() is called
1864 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1865 // group should have the destroyed bit set before waiters are notified).
1866 ensure_join(this);
1867 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1868
1869 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1870 // held by this thread must be released. The spec does not distinguish
1871 // between JNI-acquired and regular Java monitors. We can only see
1872 // regular Java monitors here if monitor enter-exit matching is broken.
1873 //
1874 // Optionally release any monitors for regular JavaThread exits. This
1875 // is provided as a work around for any bugs in monitor enter-exit
1876 // matching. This can be expensive so it is not enabled by default.
1877 //
1878 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1879 // ObjectSynchronizer::release_monitors_owned_by_thread().
1880 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1881 // Sanity check even though JNI DetachCurrentThread() would have
1882 // returned JNI_ERR if there was a Java frame. JavaThread exit
1883 // should be done executing Java code by the time we get here.
1884 assert(!this->has_last_Java_frame(),
1885 "should not have a Java frame when detaching or exiting");
1886 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1887 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1888 }
1889
1890 // These things needs to be done while we are still a Java Thread. Make sure that thread
1891 // is in a consistent state, in case GC happens
1892 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1893
1894 if (active_handles() != NULL) {
1895 JNIHandleBlock* block = active_handles();
1896 set_active_handles(NULL);
1897 JNIHandleBlock::release_block(block);
1898 }
1899
1900 if (free_handle_block() != NULL) {
1901 JNIHandleBlock* block = free_handle_block();
1902 set_free_handle_block(NULL);
1903 JNIHandleBlock::release_block(block);
1904 }
1905
1906 // These have to be removed while this is still a valid thread.
1907 remove_stack_guard_pages();
1908
1909 if (UseTLAB) {
1910 tlab().make_parsable(true); // retire TLAB
1911 }
1912
1913 if (JvmtiEnv::environments_might_exist()) {
1914 JvmtiExport::cleanup_thread(this);
1915 }
1916
1917 // We must flush any deferred card marks before removing a thread from
1918 // the list of active threads.
1919 Universe::heap()->flush_deferred_store_barrier(this);
1920 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1921
1922 #if INCLUDE_ALL_GCS
1923 // We must flush the G1-related buffers before removing a thread
1924 // from the list of active threads. We must do this after any deferred
1925 // card marks have been flushed (above) so that any entries that are
1926 // added to the thread's dirty card queue as a result are not lost.
1927 if (UseG1GC) {
1928 flush_barrier_queues();
1929 }
1930 #endif // INCLUDE_ALL_GCS
1931
1932 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1933 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1934 os::current_thread_id());
1935
1936 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1937 Threads::remove(this);
1938 }
1939
1940 #if INCLUDE_ALL_GCS
1941 // Flush G1-related queues.
1942 void JavaThread::flush_barrier_queues() {
1943 satb_mark_queue().flush();
1944 dirty_card_queue().flush();
1945 }
1946
1947 void JavaThread::initialize_queues() {
1948 assert(!SafepointSynchronize::is_at_safepoint(),
1949 "we should not be at a safepoint");
1950
1951 SATBMarkQueue& satb_queue = satb_mark_queue();
1952 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1953 // The SATB queue should have been constructed with its active
1954 // field set to false.
1955 assert(!satb_queue.is_active(), "SATB queue should not be active");
1956 assert(satb_queue.is_empty(), "SATB queue should be empty");
1957 // If we are creating the thread during a marking cycle, we should
1958 // set the active field of the SATB queue to true.
1959 if (satb_queue_set.is_active()) {
1960 satb_queue.set_active(true);
1961 }
1962
1963 DirtyCardQueue& dirty_queue = dirty_card_queue();
1964 // The dirty card queue should have been constructed with its
1965 // active field set to true.
1966 assert(dirty_queue.is_active(), "dirty card queue should be active");
1967 }
1968 #endif // INCLUDE_ALL_GCS
1969
1970 void JavaThread::cleanup_failed_attach_current_thread() {
1971 if (get_thread_profiler() != NULL) {
1972 get_thread_profiler()->disengage();
1973 ResourceMark rm;
1974 get_thread_profiler()->print(get_thread_name());
1975 }
1976
1977 if (active_handles() != NULL) {
1978 JNIHandleBlock* block = active_handles();
1979 set_active_handles(NULL);
1980 JNIHandleBlock::release_block(block);
1981 }
1982
1983 if (free_handle_block() != NULL) {
1984 JNIHandleBlock* block = free_handle_block();
1985 set_free_handle_block(NULL);
1986 JNIHandleBlock::release_block(block);
1987 }
1988
1989 // These have to be removed while this is still a valid thread.
1990 remove_stack_guard_pages();
1991
1992 if (UseTLAB) {
1993 tlab().make_parsable(true); // retire TLAB, if any
1994 }
1995
1996 #if INCLUDE_ALL_GCS
1997 if (UseG1GC) {
1998 flush_barrier_queues();
1999 }
2000 #endif // INCLUDE_ALL_GCS
2001
2002 Threads::remove(this);
2003 delete this;
2004 }
2005
2006
2007
2008
2009 JavaThread* JavaThread::active() {
2010 Thread* thread = Thread::current();
2011 if (thread->is_Java_thread()) {
2012 return (JavaThread*) thread;
2013 } else {
2014 assert(thread->is_VM_thread(), "this must be a vm thread");
2015 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2016 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2017 assert(ret->is_Java_thread(), "must be a Java thread");
2018 return ret;
2019 }
2020 }
2021
2022 bool JavaThread::is_lock_owned(address adr) const {
2023 if (Thread::is_lock_owned(adr)) return true;
2024
2025 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2026 if (chunk->contains(adr)) return true;
2027 }
2028
2029 return false;
2030 }
2031
2032
2033 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2034 chunk->set_next(monitor_chunks());
2035 set_monitor_chunks(chunk);
2036 }
2037
2038 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2039 guarantee(monitor_chunks() != NULL, "must be non empty");
2040 if (monitor_chunks() == chunk) {
2041 set_monitor_chunks(chunk->next());
2042 } else {
2043 MonitorChunk* prev = monitor_chunks();
2044 while (prev->next() != chunk) prev = prev->next();
2045 prev->set_next(chunk->next());
2046 }
2047 }
2048
2049 // JVM support.
2050
2051 // Note: this function shouldn't block if it's called in
2052 // _thread_in_native_trans state (such as from
2053 // check_special_condition_for_native_trans()).
2054 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2055
2056 if (has_last_Java_frame() && has_async_condition()) {
2057 // If we are at a polling page safepoint (not a poll return)
2058 // then we must defer async exception because live registers
2059 // will be clobbered by the exception path. Poll return is
2060 // ok because the call we a returning from already collides
2061 // with exception handling registers and so there is no issue.
2062 // (The exception handling path kills call result registers but
2063 // this is ok since the exception kills the result anyway).
2064
2065 if (is_at_poll_safepoint()) {
2066 // if the code we are returning to has deoptimized we must defer
2067 // the exception otherwise live registers get clobbered on the
2068 // exception path before deoptimization is able to retrieve them.
2069 //
2070 RegisterMap map(this, false);
2071 frame caller_fr = last_frame().sender(&map);
2072 assert(caller_fr.is_compiled_frame(), "what?");
2073 if (caller_fr.is_deoptimized_frame()) {
2074 log_info(exceptions)("deferred async exception at compiled safepoint");
2075 return;
2076 }
2077 }
2078 }
2079
2080 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2081 if (condition == _no_async_condition) {
2082 // Conditions have changed since has_special_runtime_exit_condition()
2083 // was called:
2084 // - if we were here only because of an external suspend request,
2085 // then that was taken care of above (or cancelled) so we are done
2086 // - if we were here because of another async request, then it has
2087 // been cleared between the has_special_runtime_exit_condition()
2088 // and now so again we are done
2089 return;
2090 }
2091
2092 // Check for pending async. exception
2093 if (_pending_async_exception != NULL) {
2094 // Only overwrite an already pending exception, if it is not a threadDeath.
2095 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2096
2097 // We cannot call Exceptions::_throw(...) here because we cannot block
2098 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2099
2100 if (log_is_enabled(Info, exceptions)) {
2101 ResourceMark rm;
2102 outputStream* logstream = Log(exceptions)::info_stream();
2103 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2104 if (has_last_Java_frame()) {
2105 frame f = last_frame();
2106 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2107 }
2108 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2109 }
2110 _pending_async_exception = NULL;
2111 clear_has_async_exception();
2112 }
2113 }
2114
2115 if (check_unsafe_error &&
2116 condition == _async_unsafe_access_error && !has_pending_exception()) {
2117 condition = _no_async_condition; // done
2118 switch (thread_state()) {
2119 case _thread_in_vm: {
2120 JavaThread* THREAD = this;
2121 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2122 }
2123 case _thread_in_native: {
2124 ThreadInVMfromNative tiv(this);
2125 JavaThread* THREAD = this;
2126 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2127 }
2128 case _thread_in_Java: {
2129 ThreadInVMfromJava tiv(this);
2130 JavaThread* THREAD = this;
2131 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2132 }
2133 default:
2134 ShouldNotReachHere();
2135 }
2136 }
2137
2138 assert(condition == _no_async_condition || has_pending_exception() ||
2139 (!check_unsafe_error && condition == _async_unsafe_access_error),
2140 "must have handled the async condition, if no exception");
2141 }
2142
2143 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2144 //
2145 // Check for pending external suspend. Internal suspend requests do
2146 // not use handle_special_runtime_exit_condition().
2147 // If JNIEnv proxies are allowed, don't self-suspend if the target
2148 // thread is not the current thread. In older versions of jdbx, jdbx
2149 // threads could call into the VM with another thread's JNIEnv so we
2150 // can be here operating on behalf of a suspended thread (4432884).
2151 bool do_self_suspend = is_external_suspend_with_lock();
2152 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2153 //
2154 // Because thread is external suspended the safepoint code will count
2155 // thread as at a safepoint. This can be odd because we can be here
2156 // as _thread_in_Java which would normally transition to _thread_blocked
2157 // at a safepoint. We would like to mark the thread as _thread_blocked
2158 // before calling java_suspend_self like all other callers of it but
2159 // we must then observe proper safepoint protocol. (We can't leave
2160 // _thread_blocked with a safepoint in progress). However we can be
2161 // here as _thread_in_native_trans so we can't use a normal transition
2162 // constructor/destructor pair because they assert on that type of
2163 // transition. We could do something like:
2164 //
2165 // JavaThreadState state = thread_state();
2166 // set_thread_state(_thread_in_vm);
2167 // {
2168 // ThreadBlockInVM tbivm(this);
2169 // java_suspend_self()
2170 // }
2171 // set_thread_state(_thread_in_vm_trans);
2172 // if (safepoint) block;
2173 // set_thread_state(state);
2174 //
2175 // but that is pretty messy. Instead we just go with the way the
2176 // code has worked before and note that this is the only path to
2177 // java_suspend_self that doesn't put the thread in _thread_blocked
2178 // mode.
2179
2180 frame_anchor()->make_walkable(this);
2181 java_suspend_self();
2182
2183 // We might be here for reasons in addition to the self-suspend request
2184 // so check for other async requests.
2185 }
2186
2187 if (check_asyncs) {
2188 check_and_handle_async_exceptions();
2189 }
2190 }
2191
2192 void JavaThread::send_thread_stop(oop java_throwable) {
2193 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2194 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2195 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2196
2197 // Do not throw asynchronous exceptions against the compiler thread
2198 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2199 if (!can_call_java()) return;
2200
2201 {
2202 // Actually throw the Throwable against the target Thread - however
2203 // only if there is no thread death exception installed already.
2204 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2205 // If the topmost frame is a runtime stub, then we are calling into
2206 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2207 // must deoptimize the caller before continuing, as the compiled exception handler table
2208 // may not be valid
2209 if (has_last_Java_frame()) {
2210 frame f = last_frame();
2211 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2212 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2213 RegisterMap reg_map(this, UseBiasedLocking);
2214 frame compiled_frame = f.sender(®_map);
2215 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2216 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2217 }
2218 }
2219 }
2220
2221 // Set async. pending exception in thread.
2222 set_pending_async_exception(java_throwable);
2223
2224 if (log_is_enabled(Info, exceptions)) {
2225 ResourceMark rm;
2226 log_info(exceptions)("Pending Async. exception installed of type: %s",
2227 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2228 }
2229 // for AbortVMOnException flag
2230 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2231 }
2232 }
2233
2234
2235 // Interrupt thread so it will wake up from a potential wait()
2236 Thread::interrupt(this);
2237 }
2238
2239 // External suspension mechanism.
2240 //
2241 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2242 // to any VM_locks and it is at a transition
2243 // Self-suspension will happen on the transition out of the vm.
2244 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2245 //
2246 // Guarantees on return:
2247 // + Target thread will not execute any new bytecode (that's why we need to
2248 // force a safepoint)
2249 // + Target thread will not enter any new monitors
2250 //
2251 void JavaThread::java_suspend() {
2252 { MutexLocker mu(Threads_lock);
2253 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2254 return;
2255 }
2256 }
2257
2258 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2259 if (!is_external_suspend()) {
2260 // a racing resume has cancelled us; bail out now
2261 return;
2262 }
2263
2264 // suspend is done
2265 uint32_t debug_bits = 0;
2266 // Warning: is_ext_suspend_completed() may temporarily drop the
2267 // SR_lock to allow the thread to reach a stable thread state if
2268 // it is currently in a transient thread state.
2269 if (is_ext_suspend_completed(false /* !called_by_wait */,
2270 SuspendRetryDelay, &debug_bits)) {
2271 return;
2272 }
2273 }
2274
2275 VM_ForceSafepoint vm_suspend;
2276 VMThread::execute(&vm_suspend);
2277 }
2278
2279 // Part II of external suspension.
2280 // A JavaThread self suspends when it detects a pending external suspend
2281 // request. This is usually on transitions. It is also done in places
2282 // where continuing to the next transition would surprise the caller,
2283 // e.g., monitor entry.
2284 //
2285 // Returns the number of times that the thread self-suspended.
2286 //
2287 // Note: DO NOT call java_suspend_self() when you just want to block current
2288 // thread. java_suspend_self() is the second stage of cooperative
2289 // suspension for external suspend requests and should only be used
2290 // to complete an external suspend request.
2291 //
2292 int JavaThread::java_suspend_self() {
2293 int ret = 0;
2294
2295 // we are in the process of exiting so don't suspend
2296 if (is_exiting()) {
2297 clear_external_suspend();
2298 return ret;
2299 }
2300
2301 assert(_anchor.walkable() ||
2302 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2303 "must have walkable stack");
2304
2305 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2306
2307 assert(!this->is_ext_suspended(),
2308 "a thread trying to self-suspend should not already be suspended");
2309
2310 if (this->is_suspend_equivalent()) {
2311 // If we are self-suspending as a result of the lifting of a
2312 // suspend equivalent condition, then the suspend_equivalent
2313 // flag is not cleared until we set the ext_suspended flag so
2314 // that wait_for_ext_suspend_completion() returns consistent
2315 // results.
2316 this->clear_suspend_equivalent();
2317 }
2318
2319 // A racing resume may have cancelled us before we grabbed SR_lock
2320 // above. Or another external suspend request could be waiting for us
2321 // by the time we return from SR_lock()->wait(). The thread
2322 // that requested the suspension may already be trying to walk our
2323 // stack and if we return now, we can change the stack out from under
2324 // it. This would be a "bad thing (TM)" and cause the stack walker
2325 // to crash. We stay self-suspended until there are no more pending
2326 // external suspend requests.
2327 while (is_external_suspend()) {
2328 ret++;
2329 this->set_ext_suspended();
2330
2331 // _ext_suspended flag is cleared by java_resume()
2332 while (is_ext_suspended()) {
2333 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2334 }
2335 }
2336
2337 return ret;
2338 }
2339
2340 #ifdef ASSERT
2341 // verify the JavaThread has not yet been published in the Threads::list, and
2342 // hence doesn't need protection from concurrent access at this stage
2343 void JavaThread::verify_not_published() {
2344 if (!Threads_lock->owned_by_self()) {
2345 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2346 assert(!Threads::includes(this),
2347 "java thread shouldn't have been published yet!");
2348 } else {
2349 assert(!Threads::includes(this),
2350 "java thread shouldn't have been published yet!");
2351 }
2352 }
2353 #endif
2354
2355 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2356 // progress or when _suspend_flags is non-zero.
2357 // Current thread needs to self-suspend if there is a suspend request and/or
2358 // block if a safepoint is in progress.
2359 // Async exception ISN'T checked.
2360 // Note only the ThreadInVMfromNative transition can call this function
2361 // directly and when thread state is _thread_in_native_trans
2362 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2363 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2364
2365 JavaThread *curJT = JavaThread::current();
2366 bool do_self_suspend = thread->is_external_suspend();
2367
2368 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2369
2370 // If JNIEnv proxies are allowed, don't self-suspend if the target
2371 // thread is not the current thread. In older versions of jdbx, jdbx
2372 // threads could call into the VM with another thread's JNIEnv so we
2373 // can be here operating on behalf of a suspended thread (4432884).
2374 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2375 JavaThreadState state = thread->thread_state();
2376
2377 // We mark this thread_blocked state as a suspend-equivalent so
2378 // that a caller to is_ext_suspend_completed() won't be confused.
2379 // The suspend-equivalent state is cleared by java_suspend_self().
2380 thread->set_suspend_equivalent();
2381
2382 // If the safepoint code sees the _thread_in_native_trans state, it will
2383 // wait until the thread changes to other thread state. There is no
2384 // guarantee on how soon we can obtain the SR_lock and complete the
2385 // self-suspend request. It would be a bad idea to let safepoint wait for
2386 // too long. Temporarily change the state to _thread_blocked to
2387 // let the VM thread know that this thread is ready for GC. The problem
2388 // of changing thread state is that safepoint could happen just after
2389 // java_suspend_self() returns after being resumed, and VM thread will
2390 // see the _thread_blocked state. We must check for safepoint
2391 // after restoring the state and make sure we won't leave while a safepoint
2392 // is in progress.
2393 thread->set_thread_state(_thread_blocked);
2394 thread->java_suspend_self();
2395 thread->set_thread_state(state);
2396 // Make sure new state is seen by VM thread
2397 if (os::is_MP()) {
2398 if (UseMembar) {
2399 // Force a fence between the write above and read below
2400 OrderAccess::fence();
2401 } else {
2402 // Must use this rather than serialization page in particular on Windows
2403 InterfaceSupport::serialize_memory(thread);
2404 }
2405 }
2406 }
2407
2408 if (SafepointSynchronize::do_call_back()) {
2409 // If we are safepointing, then block the caller which may not be
2410 // the same as the target thread (see above).
2411 SafepointSynchronize::block(curJT);
2412 }
2413
2414 if (thread->is_deopt_suspend()) {
2415 thread->clear_deopt_suspend();
2416 RegisterMap map(thread, false);
2417 frame f = thread->last_frame();
2418 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2419 f = f.sender(&map);
2420 }
2421 if (f.id() == thread->must_deopt_id()) {
2422 thread->clear_must_deopt_id();
2423 f.deoptimize(thread);
2424 } else {
2425 fatal("missed deoptimization!");
2426 }
2427 }
2428 }
2429
2430 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2431 // progress or when _suspend_flags is non-zero.
2432 // Current thread needs to self-suspend if there is a suspend request and/or
2433 // block if a safepoint is in progress.
2434 // Also check for pending async exception (not including unsafe access error).
2435 // Note only the native==>VM/Java barriers can call this function and when
2436 // thread state is _thread_in_native_trans.
2437 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2438 check_safepoint_and_suspend_for_native_trans(thread);
2439
2440 if (thread->has_async_exception()) {
2441 // We are in _thread_in_native_trans state, don't handle unsafe
2442 // access error since that may block.
2443 thread->check_and_handle_async_exceptions(false);
2444 }
2445 }
2446
2447 // This is a variant of the normal
2448 // check_special_condition_for_native_trans with slightly different
2449 // semantics for use by critical native wrappers. It does all the
2450 // normal checks but also performs the transition back into
2451 // thread_in_Java state. This is required so that critical natives
2452 // can potentially block and perform a GC if they are the last thread
2453 // exiting the GCLocker.
2454 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2455 check_special_condition_for_native_trans(thread);
2456
2457 // Finish the transition
2458 thread->set_thread_state(_thread_in_Java);
2459
2460 if (thread->do_critical_native_unlock()) {
2461 ThreadInVMfromJavaNoAsyncException tiv(thread);
2462 GCLocker::unlock_critical(thread);
2463 thread->clear_critical_native_unlock();
2464 }
2465 }
2466
2467 // We need to guarantee the Threads_lock here, since resumes are not
2468 // allowed during safepoint synchronization
2469 // Can only resume from an external suspension
2470 void JavaThread::java_resume() {
2471 assert_locked_or_safepoint(Threads_lock);
2472
2473 // Sanity check: thread is gone, has started exiting or the thread
2474 // was not externally suspended.
2475 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2476 return;
2477 }
2478
2479 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2480
2481 clear_external_suspend();
2482
2483 if (is_ext_suspended()) {
2484 clear_ext_suspended();
2485 SR_lock()->notify_all();
2486 }
2487 }
2488
2489 size_t JavaThread::_stack_red_zone_size = 0;
2490 size_t JavaThread::_stack_yellow_zone_size = 0;
2491 size_t JavaThread::_stack_reserved_zone_size = 0;
2492 size_t JavaThread::_stack_shadow_zone_size = 0;
2493
2494 void JavaThread::create_stack_guard_pages() {
2495 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2496 address low_addr = stack_end();
2497 size_t len = stack_guard_zone_size();
2498
2499 int must_commit = os::must_commit_stack_guard_pages();
2500 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2501
2502 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2503 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2504 return;
2505 }
2506
2507 if (os::guard_memory((char *) low_addr, len)) {
2508 _stack_guard_state = stack_guard_enabled;
2509 } else {
2510 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2511 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2512 if (os::uncommit_memory((char *) low_addr, len)) {
2513 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2514 }
2515 return;
2516 }
2517
2518 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2519 PTR_FORMAT "-" PTR_FORMAT ".",
2520 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2521 }
2522
2523 void JavaThread::remove_stack_guard_pages() {
2524 assert(Thread::current() == this, "from different thread");
2525 if (_stack_guard_state == stack_guard_unused) return;
2526 address low_addr = stack_end();
2527 size_t len = stack_guard_zone_size();
2528
2529 if (os::must_commit_stack_guard_pages()) {
2530 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2531 _stack_guard_state = stack_guard_unused;
2532 } else {
2533 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2534 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2535 return;
2536 }
2537 } else {
2538 if (_stack_guard_state == stack_guard_unused) return;
2539 if (os::unguard_memory((char *) low_addr, len)) {
2540 _stack_guard_state = stack_guard_unused;
2541 } else {
2542 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2543 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2544 return;
2545 }
2546 }
2547
2548 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2549 PTR_FORMAT "-" PTR_FORMAT ".",
2550 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2551 }
2552
2553 void JavaThread::enable_stack_reserved_zone() {
2554 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2555 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2556
2557 // The base notation is from the stack's point of view, growing downward.
2558 // We need to adjust it to work correctly with guard_memory()
2559 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2560
2561 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2562 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2563
2564 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2565 _stack_guard_state = stack_guard_enabled;
2566 } else {
2567 warning("Attempt to guard stack reserved zone failed.");
2568 }
2569 enable_register_stack_guard();
2570 }
2571
2572 void JavaThread::disable_stack_reserved_zone() {
2573 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2574 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2575
2576 // Simply return if called for a thread that does not use guard pages.
2577 if (_stack_guard_state == stack_guard_unused) return;
2578
2579 // The base notation is from the stack's point of view, growing downward.
2580 // We need to adjust it to work correctly with guard_memory()
2581 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2582
2583 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2584 _stack_guard_state = stack_guard_reserved_disabled;
2585 } else {
2586 warning("Attempt to unguard stack reserved zone failed.");
2587 }
2588 disable_register_stack_guard();
2589 }
2590
2591 void JavaThread::enable_stack_yellow_reserved_zone() {
2592 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2593 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2594
2595 // The base notation is from the stacks point of view, growing downward.
2596 // We need to adjust it to work correctly with guard_memory()
2597 address base = stack_red_zone_base();
2598
2599 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2600 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2601
2602 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2603 _stack_guard_state = stack_guard_enabled;
2604 } else {
2605 warning("Attempt to guard stack yellow zone failed.");
2606 }
2607 enable_register_stack_guard();
2608 }
2609
2610 void JavaThread::disable_stack_yellow_reserved_zone() {
2611 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2612 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2613
2614 // Simply return if called for a thread that does not use guard pages.
2615 if (_stack_guard_state == stack_guard_unused) return;
2616
2617 // The base notation is from the stacks point of view, growing downward.
2618 // We need to adjust it to work correctly with guard_memory()
2619 address base = stack_red_zone_base();
2620
2621 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2622 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2623 } else {
2624 warning("Attempt to unguard stack yellow zone failed.");
2625 }
2626 disable_register_stack_guard();
2627 }
2628
2629 void JavaThread::enable_stack_red_zone() {
2630 // The base notation is from the stacks point of view, growing downward.
2631 // We need to adjust it to work correctly with guard_memory()
2632 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2633 address base = stack_red_zone_base() - stack_red_zone_size();
2634
2635 guarantee(base < stack_base(), "Error calculating stack red zone");
2636 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2637
2638 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2639 warning("Attempt to guard stack red zone failed.");
2640 }
2641 }
2642
2643 void JavaThread::disable_stack_red_zone() {
2644 // The base notation is from the stacks point of view, growing downward.
2645 // We need to adjust it to work correctly with guard_memory()
2646 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2647 address base = stack_red_zone_base() - stack_red_zone_size();
2648 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2649 warning("Attempt to unguard stack red zone failed.");
2650 }
2651 }
2652
2653 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2654 // ignore is there is no stack
2655 if (!has_last_Java_frame()) return;
2656 // traverse the stack frames. Starts from top frame.
2657 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2658 frame* fr = fst.current();
2659 f(fr, fst.register_map());
2660 }
2661 }
2662
2663
2664 #ifndef PRODUCT
2665 // Deoptimization
2666 // Function for testing deoptimization
2667 void JavaThread::deoptimize() {
2668 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2669 StackFrameStream fst(this, UseBiasedLocking);
2670 bool deopt = false; // Dump stack only if a deopt actually happens.
2671 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2672 // Iterate over all frames in the thread and deoptimize
2673 for (; !fst.is_done(); fst.next()) {
2674 if (fst.current()->can_be_deoptimized()) {
2675
2676 if (only_at) {
2677 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2678 // consists of comma or carriage return separated numbers so
2679 // search for the current bci in that string.
2680 address pc = fst.current()->pc();
2681 nmethod* nm = (nmethod*) fst.current()->cb();
2682 ScopeDesc* sd = nm->scope_desc_at(pc);
2683 char buffer[8];
2684 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2685 size_t len = strlen(buffer);
2686 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2687 while (found != NULL) {
2688 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2689 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2690 // Check that the bci found is bracketed by terminators.
2691 break;
2692 }
2693 found = strstr(found + 1, buffer);
2694 }
2695 if (!found) {
2696 continue;
2697 }
2698 }
2699
2700 if (DebugDeoptimization && !deopt) {
2701 deopt = true; // One-time only print before deopt
2702 tty->print_cr("[BEFORE Deoptimization]");
2703 trace_frames();
2704 trace_stack();
2705 }
2706 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2707 }
2708 }
2709
2710 if (DebugDeoptimization && deopt) {
2711 tty->print_cr("[AFTER Deoptimization]");
2712 trace_frames();
2713 }
2714 }
2715
2716
2717 // Make zombies
2718 void JavaThread::make_zombies() {
2719 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2720 if (fst.current()->can_be_deoptimized()) {
2721 // it is a Java nmethod
2722 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2723 nm->make_not_entrant();
2724 }
2725 }
2726 }
2727 #endif // PRODUCT
2728
2729
2730 void JavaThread::deoptimized_wrt_marked_nmethods() {
2731 if (!has_last_Java_frame()) return;
2732 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2733 StackFrameStream fst(this, UseBiasedLocking);
2734 for (; !fst.is_done(); fst.next()) {
2735 if (fst.current()->should_be_deoptimized()) {
2736 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2737 }
2738 }
2739 }
2740
2741
2742 // If the caller is a NamedThread, then remember, in the current scope,
2743 // the given JavaThread in its _processed_thread field.
2744 class RememberProcessedThread: public StackObj {
2745 NamedThread* _cur_thr;
2746 public:
2747 RememberProcessedThread(JavaThread* jthr) {
2748 Thread* thread = Thread::current();
2749 if (thread->is_Named_thread()) {
2750 _cur_thr = (NamedThread *)thread;
2751 _cur_thr->set_processed_thread(jthr);
2752 } else {
2753 _cur_thr = NULL;
2754 }
2755 }
2756
2757 ~RememberProcessedThread() {
2758 if (_cur_thr) {
2759 _cur_thr->set_processed_thread(NULL);
2760 }
2761 }
2762 };
2763
2764 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2765 // Verify that the deferred card marks have been flushed.
2766 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2767
2768 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2769 // since there may be more than one thread using each ThreadProfiler.
2770
2771 // Traverse the GCHandles
2772 Thread::oops_do(f, cf);
2773
2774 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2775
2776 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2777 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2778
2779 if (has_last_Java_frame()) {
2780 // Record JavaThread to GC thread
2781 RememberProcessedThread rpt(this);
2782
2783 // Traverse the privileged stack
2784 if (_privileged_stack_top != NULL) {
2785 _privileged_stack_top->oops_do(f);
2786 }
2787
2788 // traverse the registered growable array
2789 if (_array_for_gc != NULL) {
2790 for (int index = 0; index < _array_for_gc->length(); index++) {
2791 f->do_oop(_array_for_gc->adr_at(index));
2792 }
2793 }
2794
2795 // Traverse the monitor chunks
2796 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2797 chunk->oops_do(f);
2798 }
2799
2800 // Traverse the execution stack
2801 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2802 fst.current()->oops_do(f, cf, fst.register_map());
2803 }
2804 }
2805
2806 // callee_target is never live across a gc point so NULL it here should
2807 // it still contain a methdOop.
2808
2809 set_callee_target(NULL);
2810
2811 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2812 // If we have deferred set_locals there might be oops waiting to be
2813 // written
2814 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2815 if (list != NULL) {
2816 for (int i = 0; i < list->length(); i++) {
2817 list->at(i)->oops_do(f);
2818 }
2819 }
2820
2821 // Traverse instance variables at the end since the GC may be moving things
2822 // around using this function
2823 f->do_oop((oop*) &_threadObj);
2824 f->do_oop((oop*) &_vm_result);
2825 f->do_oop((oop*) &_exception_oop);
2826 f->do_oop((oop*) &_pending_async_exception);
2827
2828 if (jvmti_thread_state() != NULL) {
2829 jvmti_thread_state()->oops_do(f);
2830 }
2831 }
2832
2833 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
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_raw("\"");
2893 st->print_raw(get_thread_name());
2894 st->print_raw("\" ");
2895 oop thread_oop = threadObj();
2896 if (thread_oop != NULL) {
2897 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2898 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2899 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2900 }
2901 Thread::print_on(st);
2902 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2903 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2904 if (thread_oop != NULL) {
2905 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2906 }
2907 #ifndef PRODUCT
2908 print_thread_state_on(st);
2909 _safepoint_state->print_on(st);
2910 #endif // PRODUCT
2911 if (is_Compiler_thread()) {
2912 CompilerThread* ct = (CompilerThread*)this;
2913 if (ct->task() != NULL) {
2914 st->print(" Compiling: ");
2915 ct->task()->print(st, NULL, true, false);
2916 } else {
2917 st->print(" No compile task");
2918 }
2919 st->cr();
2920 }
2921 }
2922
2923 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2924 st->print("%s", get_thread_name_string(buf, buflen));
2925 }
2926
2927 // Called by fatal error handler. The difference between this and
2928 // JavaThread::print() is that we can't grab lock or allocate memory.
2929 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2930 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2931 oop thread_obj = threadObj();
2932 if (thread_obj != NULL) {
2933 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2934 }
2935 st->print(" [");
2936 st->print("%s", _get_thread_state_name(_thread_state));
2937 if (osthread()) {
2938 st->print(", id=%d", osthread()->thread_id());
2939 }
2940 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2941 p2i(stack_end()), p2i(stack_base()));
2942 st->print("]");
2943 return;
2944 }
2945
2946 // Verification
2947
2948 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2949
2950 void JavaThread::verify() {
2951 // Verify oops in the thread.
2952 oops_do(&VerifyOopClosure::verify_oop, NULL);
2953
2954 // Verify the stack frames.
2955 frames_do(frame_verify);
2956 }
2957
2958 // CR 6300358 (sub-CR 2137150)
2959 // Most callers of this method assume that it can't return NULL but a
2960 // thread may not have a name whilst it is in the process of attaching to
2961 // the VM - see CR 6412693, and there are places where a JavaThread can be
2962 // seen prior to having it's threadObj set (eg JNI attaching threads and
2963 // if vm exit occurs during initialization). These cases can all be accounted
2964 // for such that this method never returns NULL.
2965 const char* JavaThread::get_thread_name() const {
2966 #ifdef ASSERT
2967 // early safepoints can hit while current thread does not yet have TLS
2968 if (!SafepointSynchronize::is_at_safepoint()) {
2969 Thread *cur = Thread::current();
2970 if (!(cur->is_Java_thread() && cur == this)) {
2971 // Current JavaThreads are allowed to get their own name without
2972 // the Threads_lock.
2973 assert_locked_or_safepoint(Threads_lock);
2974 }
2975 }
2976 #endif // ASSERT
2977 return get_thread_name_string();
2978 }
2979
2980 // Returns a non-NULL representation of this thread's name, or a suitable
2981 // descriptive string if there is no set name
2982 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2983 const char* name_str;
2984 oop thread_obj = threadObj();
2985 if (thread_obj != NULL) {
2986 oop name = java_lang_Thread::name(thread_obj);
2987 if (name != NULL) {
2988 if (buf == NULL) {
2989 name_str = java_lang_String::as_utf8_string(name);
2990 } else {
2991 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2992 }
2993 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2994 name_str = "<no-name - thread is attaching>";
2995 } else {
2996 name_str = Thread::name();
2997 }
2998 } else {
2999 name_str = Thread::name();
3000 }
3001 assert(name_str != NULL, "unexpected NULL thread name");
3002 return name_str;
3003 }
3004
3005
3006 const char* JavaThread::get_threadgroup_name() const {
3007 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3008 oop thread_obj = threadObj();
3009 if (thread_obj != NULL) {
3010 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3011 if (thread_group != NULL) {
3012 // ThreadGroup.name can be null
3013 return java_lang_ThreadGroup::name(thread_group);
3014 }
3015 }
3016 return NULL;
3017 }
3018
3019 const char* JavaThread::get_parent_name() const {
3020 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3021 oop thread_obj = threadObj();
3022 if (thread_obj != NULL) {
3023 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3024 if (thread_group != NULL) {
3025 oop parent = java_lang_ThreadGroup::parent(thread_group);
3026 if (parent != NULL) {
3027 // ThreadGroup.name can be null
3028 return java_lang_ThreadGroup::name(parent);
3029 }
3030 }
3031 }
3032 return NULL;
3033 }
3034
3035 ThreadPriority JavaThread::java_priority() const {
3036 oop thr_oop = threadObj();
3037 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3038 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3039 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3040 return priority;
3041 }
3042
3043 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3044
3045 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3046 // Link Java Thread object <-> C++ Thread
3047
3048 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3049 // and put it into a new Handle. The Handle "thread_oop" can then
3050 // be used to pass the C++ thread object to other methods.
3051
3052 // Set the Java level thread object (jthread) field of the
3053 // new thread (a JavaThread *) to C++ thread object using the
3054 // "thread_oop" handle.
3055
3056 // Set the thread field (a JavaThread *) of the
3057 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3058
3059 Handle thread_oop(Thread::current(),
3060 JNIHandles::resolve_non_null(jni_thread));
3061 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3062 "must be initialized");
3063 set_threadObj(thread_oop());
3064 java_lang_Thread::set_thread(thread_oop(), this);
3065
3066 if (prio == NoPriority) {
3067 prio = java_lang_Thread::priority(thread_oop());
3068 assert(prio != NoPriority, "A valid priority should be present");
3069 }
3070
3071 // Push the Java priority down to the native thread; needs Threads_lock
3072 Thread::set_priority(this, prio);
3073
3074 prepare_ext();
3075
3076 // Add the new thread to the Threads list and set it in motion.
3077 // We must have threads lock in order to call Threads::add.
3078 // It is crucial that we do not block before the thread is
3079 // added to the Threads list for if a GC happens, then the java_thread oop
3080 // will not be visited by GC.
3081 Threads::add(this);
3082 }
3083
3084 oop JavaThread::current_park_blocker() {
3085 // Support for JSR-166 locks
3086 oop thread_oop = threadObj();
3087 if (thread_oop != NULL &&
3088 JDK_Version::current().supports_thread_park_blocker()) {
3089 return java_lang_Thread::park_blocker(thread_oop);
3090 }
3091 return NULL;
3092 }
3093
3094
3095 void JavaThread::print_stack_on(outputStream* st) {
3096 if (!has_last_Java_frame()) return;
3097 ResourceMark rm;
3098 HandleMark hm;
3099
3100 RegisterMap reg_map(this);
3101 vframe* start_vf = last_java_vframe(®_map);
3102 int count = 0;
3103 for (vframe* f = start_vf; f; f = f->sender()) {
3104 if (f->is_java_frame()) {
3105 javaVFrame* jvf = javaVFrame::cast(f);
3106 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3107
3108 // Print out lock information
3109 if (JavaMonitorsInStackTrace) {
3110 jvf->print_lock_info_on(st, count);
3111 }
3112 } else {
3113 // Ignore non-Java frames
3114 }
3115
3116 // Bail-out case for too deep stacks
3117 count++;
3118 if (MaxJavaStackTraceDepth == count) return;
3119 }
3120 }
3121
3122
3123 // JVMTI PopFrame support
3124 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3125 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3126 if (in_bytes(size_in_bytes) != 0) {
3127 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3128 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3129 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3130 }
3131 }
3132
3133 void* JavaThread::popframe_preserved_args() {
3134 return _popframe_preserved_args;
3135 }
3136
3137 ByteSize JavaThread::popframe_preserved_args_size() {
3138 return in_ByteSize(_popframe_preserved_args_size);
3139 }
3140
3141 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3142 int sz = in_bytes(popframe_preserved_args_size());
3143 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3144 return in_WordSize(sz / wordSize);
3145 }
3146
3147 void JavaThread::popframe_free_preserved_args() {
3148 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3149 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3150 _popframe_preserved_args = NULL;
3151 _popframe_preserved_args_size = 0;
3152 }
3153
3154 #ifndef PRODUCT
3155
3156 void JavaThread::trace_frames() {
3157 tty->print_cr("[Describe stack]");
3158 int frame_no = 1;
3159 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3160 tty->print(" %d. ", frame_no++);
3161 fst.current()->print_value_on(tty, this);
3162 tty->cr();
3163 }
3164 }
3165
3166 class PrintAndVerifyOopClosure: public OopClosure {
3167 protected:
3168 template <class T> inline void do_oop_work(T* p) {
3169 oop obj = oopDesc::load_decode_heap_oop(p);
3170 if (obj == NULL) return;
3171 tty->print(INTPTR_FORMAT ": ", p2i(p));
3172 if (obj->is_oop_or_null()) {
3173 if (obj->is_objArray()) {
3174 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3175 } else {
3176 obj->print();
3177 }
3178 } else {
3179 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3180 }
3181 tty->cr();
3182 }
3183 public:
3184 virtual void do_oop(oop* p) { do_oop_work(p); }
3185 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3186 };
3187
3188
3189 static void oops_print(frame* f, const RegisterMap *map) {
3190 PrintAndVerifyOopClosure print;
3191 f->print_value();
3192 f->oops_do(&print, NULL, (RegisterMap*)map);
3193 }
3194
3195 // Print our all the locations that contain oops and whether they are
3196 // valid or not. This useful when trying to find the oldest frame
3197 // where an oop has gone bad since the frame walk is from youngest to
3198 // oldest.
3199 void JavaThread::trace_oops() {
3200 tty->print_cr("[Trace oops]");
3201 frames_do(oops_print);
3202 }
3203
3204
3205 #ifdef ASSERT
3206 // Print or validate the layout of stack frames
3207 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3208 ResourceMark rm;
3209 PRESERVE_EXCEPTION_MARK;
3210 FrameValues values;
3211 int frame_no = 0;
3212 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3213 fst.current()->describe(values, ++frame_no);
3214 if (depth == frame_no) break;
3215 }
3216 if (validate_only) {
3217 values.validate();
3218 } else {
3219 tty->print_cr("[Describe stack layout]");
3220 values.print(this);
3221 }
3222 }
3223 #endif
3224
3225 void JavaThread::trace_stack_from(vframe* start_vf) {
3226 ResourceMark rm;
3227 int vframe_no = 1;
3228 for (vframe* f = start_vf; f; f = f->sender()) {
3229 if (f->is_java_frame()) {
3230 javaVFrame::cast(f)->print_activation(vframe_no++);
3231 } else {
3232 f->print();
3233 }
3234 if (vframe_no > StackPrintLimit) {
3235 tty->print_cr("...<more frames>...");
3236 return;
3237 }
3238 }
3239 }
3240
3241
3242 void JavaThread::trace_stack() {
3243 if (!has_last_Java_frame()) return;
3244 ResourceMark rm;
3245 HandleMark hm;
3246 RegisterMap reg_map(this);
3247 trace_stack_from(last_java_vframe(®_map));
3248 }
3249
3250
3251 #endif // PRODUCT
3252
3253
3254 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3255 assert(reg_map != NULL, "a map must be given");
3256 frame f = last_frame();
3257 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3258 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3259 }
3260 return NULL;
3261 }
3262
3263
3264 Klass* JavaThread::security_get_caller_class(int depth) {
3265 vframeStream vfst(this);
3266 vfst.security_get_caller_frame(depth);
3267 if (!vfst.at_end()) {
3268 return vfst.method()->method_holder();
3269 }
3270 return NULL;
3271 }
3272
3273 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3274 assert(thread->is_Compiler_thread(), "must be compiler thread");
3275 CompileBroker::compiler_thread_loop();
3276 }
3277
3278 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3279 NMethodSweeper::sweeper_loop();
3280 }
3281
3282 // Create a CompilerThread
3283 CompilerThread::CompilerThread(CompileQueue* queue,
3284 CompilerCounters* counters)
3285 : JavaThread(&compiler_thread_entry) {
3286 _env = NULL;
3287 _log = NULL;
3288 _task = NULL;
3289 _queue = queue;
3290 _counters = counters;
3291 _buffer_blob = NULL;
3292 _compiler = NULL;
3293
3294 #ifndef PRODUCT
3295 _ideal_graph_printer = NULL;
3296 #endif
3297 }
3298
3299 bool CompilerThread::can_call_java() const {
3300 return _compiler != NULL && _compiler->is_jvmci();
3301 }
3302
3303 // Create sweeper thread
3304 CodeCacheSweeperThread::CodeCacheSweeperThread()
3305 : JavaThread(&sweeper_thread_entry) {
3306 _scanned_compiled_method = NULL;
3307 }
3308
3309 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3310 JavaThread::oops_do(f, cf);
3311 if (_scanned_compiled_method != NULL && cf != NULL) {
3312 // Safepoints can occur when the sweeper is scanning an nmethod so
3313 // process it here to make sure it isn't unloaded in the middle of
3314 // a scan.
3315 cf->do_code_blob(_scanned_compiled_method);
3316 }
3317 }
3318
3319 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3320 JavaThread::nmethods_do(cf);
3321 if (_scanned_compiled_method != NULL && cf != NULL) {
3322 // Safepoints can occur when the sweeper is scanning an nmethod so
3323 // process it here to make sure it isn't unloaded in the middle of
3324 // a scan.
3325 cf->do_code_blob(_scanned_compiled_method);
3326 }
3327 }
3328
3329
3330 // ======= Threads ========
3331
3332 // The Threads class links together all active threads, and provides
3333 // operations over all threads. It is protected by its own Mutex
3334 // lock, which is also used in other contexts to protect thread
3335 // operations from having the thread being operated on from exiting
3336 // and going away unexpectedly (e.g., safepoint synchronization)
3337
3338 JavaThread* Threads::_thread_list = NULL;
3339 int Threads::_number_of_threads = 0;
3340 int Threads::_number_of_non_daemon_threads = 0;
3341 int Threads::_return_code = 0;
3342 int Threads::_thread_claim_parity = 0;
3343 size_t JavaThread::_stack_size_at_create = 0;
3344 #ifdef ASSERT
3345 bool Threads::_vm_complete = false;
3346 #endif
3347
3348 // All JavaThreads
3349 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3350
3351 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3352 void Threads::threads_do(ThreadClosure* tc) {
3353 assert_locked_or_safepoint(Threads_lock);
3354 // ALL_JAVA_THREADS iterates through all JavaThreads
3355 ALL_JAVA_THREADS(p) {
3356 tc->do_thread(p);
3357 }
3358 // Someday we could have a table or list of all non-JavaThreads.
3359 // For now, just manually iterate through them.
3360 tc->do_thread(VMThread::vm_thread());
3361 Universe::heap()->gc_threads_do(tc);
3362 WatcherThread *wt = WatcherThread::watcher_thread();
3363 // Strictly speaking, the following NULL check isn't sufficient to make sure
3364 // the data for WatcherThread is still valid upon being examined. However,
3365 // considering that WatchThread terminates when the VM is on the way to
3366 // exit at safepoint, the chance of the above is extremely small. The right
3367 // way to prevent termination of WatcherThread would be to acquire
3368 // Terminator_lock, but we can't do that without violating the lock rank
3369 // checking in some cases.
3370 if (wt != NULL) {
3371 tc->do_thread(wt);
3372 }
3373
3374 // If CompilerThreads ever become non-JavaThreads, add them here
3375 }
3376
3377 // The system initialization in the library has three phases.
3378 //
3379 // Phase 1: java.lang.System class initialization
3380 // java.lang.System is a primordial class loaded and initialized
3381 // by the VM early during startup. java.lang.System.<clinit>
3382 // only does registerNatives and keeps the rest of the class
3383 // initialization work later until thread initialization completes.
3384 //
3385 // System.initPhase1 initializes the system properties, the static
3386 // fields in, out, and err. Set up java signal handlers, OS-specific
3387 // system settings, and thread group of the main thread.
3388 static void call_initPhase1(TRAPS) {
3389 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3390 instanceKlassHandle klass (THREAD, k);
3391
3392 JavaValue result(T_VOID);
3393 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3394 vmSymbols::void_method_signature(), CHECK);
3395 }
3396
3397 // Phase 2. Module system initialization
3398 // This will initialize the module system. Only java.base classes
3399 // can be loaded until phase 2 completes.
3400 //
3401 // Call System.initPhase2 after the compiler initialization and jsr292
3402 // classes get initialized because module initialization runs a lot of java
3403 // code, that for performance reasons, should be compiled. Also, this will
3404 // enable the startup code to use lambda and other language features in this
3405 // phase and onward.
3406 //
3407 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3408 static void call_initPhase2(TRAPS) {
3409 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3410
3411 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3412 instanceKlassHandle klass (THREAD, k);
3413
3414 JavaValue result(T_VOID);
3415 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3416 vmSymbols::void_method_signature(), CHECK);
3417 universe_post_module_init();
3418 }
3419
3420 // Phase 3. final setup - set security manager, system class loader and TCCL
3421 //
3422 // This will instantiate and set the security manager, set the system class
3423 // loader as well as the thread context class loader. The security manager
3424 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3425 // other modules or the application's classpath.
3426 static void call_initPhase3(TRAPS) {
3427 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3428 instanceKlassHandle klass (THREAD, k);
3429
3430 JavaValue result(T_VOID);
3431 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3432 vmSymbols::void_method_signature(), CHECK);
3433 }
3434
3435 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3436 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3437
3438 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3439 create_vm_init_libraries();
3440 }
3441
3442 initialize_class(vmSymbols::java_lang_String(), CHECK);
3443
3444 // Inject CompactStrings value after the static initializers for String ran.
3445 java_lang_String::set_compact_strings(CompactStrings);
3446
3447 // Initialize java_lang.System (needed before creating the thread)
3448 initialize_class(vmSymbols::java_lang_System(), CHECK);
3449 // The VM creates & returns objects of this class. Make sure it's initialized.
3450 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3451 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3452 Handle thread_group = create_initial_thread_group(CHECK);
3453 Universe::set_main_thread_group(thread_group());
3454 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3455 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3456 main_thread->set_threadObj(thread_object);
3457 // Set thread status to running since main thread has
3458 // been started and running.
3459 java_lang_Thread::set_thread_status(thread_object,
3460 java_lang_Thread::RUNNABLE);
3461
3462 // The VM creates objects of this class.
3463 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3464
3465 // The VM preresolves methods to these classes. Make sure that they get initialized
3466 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3467 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3468
3469 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3470 call_initPhase1(CHECK);
3471
3472 // get the Java runtime name after java.lang.System is initialized
3473 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3474 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3475
3476 // an instance of OutOfMemory exception has been allocated earlier
3477 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3478 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3479 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3480 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3481 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3482 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3483 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3484 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3485 }
3486
3487 void Threads::initialize_jsr292_core_classes(TRAPS) {
3488 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3489
3490 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3491 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3492 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3493 }
3494
3495 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3496 extern void JDK_Version_init();
3497
3498 // Preinitialize version info.
3499 VM_Version::early_initialize();
3500
3501 // Check version
3502 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3503
3504 // Initialize library-based TLS
3505 ThreadLocalStorage::init();
3506
3507 // Initialize the output stream module
3508 ostream_init();
3509
3510 // Process java launcher properties.
3511 Arguments::process_sun_java_launcher_properties(args);
3512
3513 // Initialize the os module
3514 os::init();
3515
3516 // Record VM creation timing statistics
3517 TraceVmCreationTime create_vm_timer;
3518 create_vm_timer.start();
3519
3520 // Initialize system properties.
3521 Arguments::init_system_properties();
3522
3523 // So that JDK version can be used as a discriminator when parsing arguments
3524 JDK_Version_init();
3525
3526 // Update/Initialize System properties after JDK version number is known
3527 Arguments::init_version_specific_system_properties();
3528
3529 // Make sure to initialize log configuration *before* parsing arguments
3530 LogConfiguration::initialize(create_vm_timer.begin_time());
3531
3532 // Parse arguments
3533 jint parse_result = Arguments::parse(args);
3534 if (parse_result != JNI_OK) return parse_result;
3535
3536 os::init_before_ergo();
3537
3538 jint ergo_result = Arguments::apply_ergo();
3539 if (ergo_result != JNI_OK) return ergo_result;
3540
3541 // Final check of all ranges after ergonomics which may change values.
3542 if (!CommandLineFlagRangeList::check_ranges()) {
3543 return JNI_EINVAL;
3544 }
3545
3546 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3547 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3548 if (!constraint_result) {
3549 return JNI_EINVAL;
3550 }
3551
3552 CommandLineFlagWriteableList::mark_startup();
3553
3554 if (PauseAtStartup) {
3555 os::pause();
3556 }
3557
3558 HOTSPOT_VM_INIT_BEGIN();
3559
3560 // Timing (must come after argument parsing)
3561 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3562
3563 // Initialize the os module after parsing the args
3564 jint os_init_2_result = os::init_2();
3565 if (os_init_2_result != JNI_OK) return os_init_2_result;
3566
3567 jint adjust_after_os_result = Arguments::adjust_after_os();
3568 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3569
3570 // Initialize output stream logging
3571 ostream_init_log();
3572
3573 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3574 // Must be before create_vm_init_agents()
3575 if (Arguments::init_libraries_at_startup()) {
3576 convert_vm_init_libraries_to_agents();
3577 }
3578
3579 // Launch -agentlib/-agentpath and converted -Xrun agents
3580 if (Arguments::init_agents_at_startup()) {
3581 create_vm_init_agents();
3582 }
3583
3584 // Initialize Threads state
3585 _thread_list = NULL;
3586 _number_of_threads = 0;
3587 _number_of_non_daemon_threads = 0;
3588
3589 // Initialize global data structures and create system classes in heap
3590 vm_init_globals();
3591
3592 #if INCLUDE_JVMCI
3593 if (JVMCICounterSize > 0) {
3594 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3595 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3596 } else {
3597 JavaThread::_jvmci_old_thread_counters = NULL;
3598 }
3599 #endif // INCLUDE_JVMCI
3600
3601 // Attach the main thread to this os thread
3602 JavaThread* main_thread = new JavaThread();
3603 main_thread->set_thread_state(_thread_in_vm);
3604 main_thread->initialize_thread_current();
3605 // must do this before set_active_handles
3606 main_thread->record_stack_base_and_size();
3607 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3608
3609 if (!main_thread->set_as_starting_thread()) {
3610 vm_shutdown_during_initialization(
3611 "Failed necessary internal allocation. Out of swap space");
3612 delete main_thread;
3613 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3614 return JNI_ENOMEM;
3615 }
3616
3617 // Enable guard page *after* os::create_main_thread(), otherwise it would
3618 // crash Linux VM, see notes in os_linux.cpp.
3619 main_thread->create_stack_guard_pages();
3620
3621 // Initialize Java-Level synchronization subsystem
3622 ObjectMonitor::Initialize();
3623
3624 // Initialize global modules
3625 jint status = init_globals();
3626 if (status != JNI_OK) {
3627 delete main_thread;
3628 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3629 return status;
3630 }
3631
3632 if (TRACE_INITIALIZE() != JNI_OK) {
3633 vm_exit_during_initialization("Failed to initialize tracing backend");
3634 }
3635
3636 // Should be done after the heap is fully created
3637 main_thread->cache_global_variables();
3638
3639 HandleMark hm;
3640
3641 { MutexLocker mu(Threads_lock);
3642 Threads::add(main_thread);
3643 }
3644
3645 // Any JVMTI raw monitors entered in onload will transition into
3646 // real raw monitor. VM is setup enough here for raw monitor enter.
3647 JvmtiExport::transition_pending_onload_raw_monitors();
3648
3649 // Create the VMThread
3650 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3651
3652 VMThread::create();
3653 Thread* vmthread = VMThread::vm_thread();
3654
3655 if (!os::create_thread(vmthread, os::vm_thread)) {
3656 vm_exit_during_initialization("Cannot create VM thread. "
3657 "Out of system resources.");
3658 }
3659
3660 // Wait for the VM thread to become ready, and VMThread::run to initialize
3661 // Monitors can have spurious returns, must always check another state flag
3662 {
3663 MutexLocker ml(Notify_lock);
3664 os::start_thread(vmthread);
3665 while (vmthread->active_handles() == NULL) {
3666 Notify_lock->wait();
3667 }
3668 }
3669 }
3670
3671 assert(Universe::is_fully_initialized(), "not initialized");
3672 if (VerifyDuringStartup) {
3673 // Make sure we're starting with a clean slate.
3674 VM_Verify verify_op;
3675 VMThread::execute(&verify_op);
3676 }
3677
3678 Thread* THREAD = Thread::current();
3679
3680 // At this point, the Universe is initialized, but we have not executed
3681 // any byte code. Now is a good time (the only time) to dump out the
3682 // internal state of the JVM for sharing.
3683 if (DumpSharedSpaces) {
3684 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3685 ShouldNotReachHere();
3686 }
3687
3688 // Always call even when there are not JVMTI environments yet, since environments
3689 // may be attached late and JVMTI must track phases of VM execution
3690 JvmtiExport::enter_early_start_phase();
3691
3692 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3693 JvmtiExport::post_early_vm_start();
3694
3695 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3696
3697 // We need this for ClassDataSharing - the initial vm.info property is set
3698 // with the default value of CDS "sharing" which may be reset through
3699 // command line options.
3700 reset_vm_info_property(CHECK_JNI_ERR);
3701
3702 quicken_jni_functions();
3703
3704 // No more stub generation allowed after that point.
3705 StubCodeDesc::freeze();
3706
3707 // Set flag that basic initialization has completed. Used by exceptions and various
3708 // debug stuff, that does not work until all basic classes have been initialized.
3709 set_init_completed();
3710
3711 LogConfiguration::post_initialize();
3712 Metaspace::post_initialize();
3713
3714 HOTSPOT_VM_INIT_END();
3715
3716 // record VM initialization completion time
3717 #if INCLUDE_MANAGEMENT
3718 Management::record_vm_init_completed();
3719 #endif // INCLUDE_MANAGEMENT
3720
3721 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3722 // set_init_completed has just been called, causing exceptions not to be shortcut
3723 // anymore. We call vm_exit_during_initialization directly instead.
3724
3725 // Initialize reference pending list locker
3726 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3727 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3728
3729 // Signal Dispatcher needs to be started before VMInit event is posted
3730 os::signal_init();
3731
3732 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3733 if (!DisableAttachMechanism) {
3734 AttachListener::vm_start();
3735 if (StartAttachListener || AttachListener::init_at_startup()) {
3736 AttachListener::init();
3737 }
3738 }
3739
3740 // Launch -Xrun agents
3741 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3742 // back-end can launch with -Xdebug -Xrunjdwp.
3743 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3744 create_vm_init_libraries();
3745 }
3746
3747 if (CleanChunkPoolAsync) {
3748 Chunk::start_chunk_pool_cleaner_task();
3749 }
3750
3751 // initialize compiler(s)
3752 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3753 CompileBroker::compilation_init(CHECK_JNI_ERR);
3754 #endif
3755
3756 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3757 // It is done after compilers are initialized, because otherwise compilations of
3758 // signature polymorphic MH intrinsics can be missed
3759 // (see SystemDictionary::find_method_handle_intrinsic).
3760 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3761
3762 // This will initialize the module system. Only java.base classes can be
3763 // loaded until phase 2 completes
3764 call_initPhase2(CHECK_JNI_ERR);
3765
3766 // Always call even when there are not JVMTI environments yet, since environments
3767 // may be attached late and JVMTI must track phases of VM execution
3768 JvmtiExport::enter_start_phase();
3769
3770 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3771 JvmtiExport::post_vm_start();
3772
3773 // Final system initialization including security manager and system class loader
3774 call_initPhase3(CHECK_JNI_ERR);
3775
3776 // cache the system class loader
3777 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3778
3779 #if INCLUDE_JVMCI
3780 if (EnableJVMCI && UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation)) {
3781 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3782 // compilations via JVMCI will not actually block until JVMCI is initialized.
3783 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3784 }
3785 #endif
3786
3787 // Always call even when there are not JVMTI environments yet, since environments
3788 // may be attached late and JVMTI must track phases of VM execution
3789 JvmtiExport::enter_live_phase();
3790
3791 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3792 JvmtiExport::post_vm_initialized();
3793
3794 if (TRACE_START() != JNI_OK) {
3795 vm_exit_during_initialization("Failed to start tracing backend.");
3796 }
3797
3798 #if INCLUDE_MANAGEMENT
3799 Management::initialize(THREAD);
3800
3801 if (HAS_PENDING_EXCEPTION) {
3802 // management agent fails to start possibly due to
3803 // configuration problem and is responsible for printing
3804 // stack trace if appropriate. Simply exit VM.
3805 vm_exit(1);
3806 }
3807 #endif // INCLUDE_MANAGEMENT
3808
3809 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3810 if (MemProfiling) MemProfiler::engage();
3811 StatSampler::engage();
3812 if (CheckJNICalls) JniPeriodicChecker::engage();
3813
3814 BiasedLocking::init();
3815
3816 #if INCLUDE_RTM_OPT
3817 RTMLockingCounters::init();
3818 #endif
3819
3820 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3821 call_postVMInitHook(THREAD);
3822 // The Java side of PostVMInitHook.run must deal with all
3823 // exceptions and provide means of diagnosis.
3824 if (HAS_PENDING_EXCEPTION) {
3825 CLEAR_PENDING_EXCEPTION;
3826 }
3827 }
3828
3829 {
3830 MutexLocker ml(PeriodicTask_lock);
3831 // Make sure the WatcherThread can be started by WatcherThread::start()
3832 // or by dynamic enrollment.
3833 WatcherThread::make_startable();
3834 // Start up the WatcherThread if there are any periodic tasks
3835 // NOTE: All PeriodicTasks should be registered by now. If they
3836 // aren't, late joiners might appear to start slowly (we might
3837 // take a while to process their first tick).
3838 if (PeriodicTask::num_tasks() > 0) {
3839 WatcherThread::start();
3840 }
3841 }
3842
3843 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3844
3845 create_vm_timer.end();
3846 #ifdef ASSERT
3847 _vm_complete = true;
3848 #endif
3849 return JNI_OK;
3850 }
3851
3852 // type for the Agent_OnLoad and JVM_OnLoad entry points
3853 extern "C" {
3854 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3855 }
3856 // Find a command line agent library and return its entry point for
3857 // -agentlib: -agentpath: -Xrun
3858 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3859 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3860 const char *on_load_symbols[],
3861 size_t num_symbol_entries) {
3862 OnLoadEntry_t on_load_entry = NULL;
3863 void *library = NULL;
3864
3865 if (!agent->valid()) {
3866 char buffer[JVM_MAXPATHLEN];
3867 char ebuf[1024] = "";
3868 const char *name = agent->name();
3869 const char *msg = "Could not find agent library ";
3870
3871 // First check to see if agent is statically linked into executable
3872 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3873 library = agent->os_lib();
3874 } else if (agent->is_absolute_path()) {
3875 library = os::dll_load(name, ebuf, sizeof ebuf);
3876 if (library == NULL) {
3877 const char *sub_msg = " in absolute path, with error: ";
3878 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3879 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3880 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3881 // If we can't find the agent, exit.
3882 vm_exit_during_initialization(buf, NULL);
3883 FREE_C_HEAP_ARRAY(char, buf);
3884 }
3885 } else {
3886 // Try to load the agent from the standard dll directory
3887 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3888 name)) {
3889 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3890 }
3891 if (library == NULL) { // Try the local directory
3892 char ns[1] = {0};
3893 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3894 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3895 }
3896 if (library == NULL) {
3897 const char *sub_msg = " on the library path, with error: ";
3898 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3899 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3900 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3901 // If we can't find the agent, exit.
3902 vm_exit_during_initialization(buf, NULL);
3903 FREE_C_HEAP_ARRAY(char, buf);
3904 }
3905 }
3906 }
3907 agent->set_os_lib(library);
3908 agent->set_valid();
3909 }
3910
3911 // Find the OnLoad function.
3912 on_load_entry =
3913 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3914 false,
3915 on_load_symbols,
3916 num_symbol_entries));
3917 return on_load_entry;
3918 }
3919
3920 // Find the JVM_OnLoad entry point
3921 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3922 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3923 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3924 }
3925
3926 // Find the Agent_OnLoad entry point
3927 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3928 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3929 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3930 }
3931
3932 // For backwards compatibility with -Xrun
3933 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3934 // treated like -agentpath:
3935 // Must be called before agent libraries are created
3936 void Threads::convert_vm_init_libraries_to_agents() {
3937 AgentLibrary* agent;
3938 AgentLibrary* next;
3939
3940 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3941 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3942 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3943
3944 // If there is an JVM_OnLoad function it will get called later,
3945 // otherwise see if there is an Agent_OnLoad
3946 if (on_load_entry == NULL) {
3947 on_load_entry = lookup_agent_on_load(agent);
3948 if (on_load_entry != NULL) {
3949 // switch it to the agent list -- so that Agent_OnLoad will be called,
3950 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3951 Arguments::convert_library_to_agent(agent);
3952 } else {
3953 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3954 }
3955 }
3956 }
3957 }
3958
3959 // Create agents for -agentlib: -agentpath: and converted -Xrun
3960 // Invokes Agent_OnLoad
3961 // Called very early -- before JavaThreads exist
3962 void Threads::create_vm_init_agents() {
3963 extern struct JavaVM_ main_vm;
3964 AgentLibrary* agent;
3965
3966 JvmtiExport::enter_onload_phase();
3967
3968 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3969 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3970
3971 if (on_load_entry != NULL) {
3972 // Invoke the Agent_OnLoad function
3973 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3974 if (err != JNI_OK) {
3975 vm_exit_during_initialization("agent library failed to init", agent->name());
3976 }
3977 } else {
3978 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3979 }
3980 }
3981 JvmtiExport::enter_primordial_phase();
3982 }
3983
3984 extern "C" {
3985 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3986 }
3987
3988 void Threads::shutdown_vm_agents() {
3989 // Send any Agent_OnUnload notifications
3990 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3991 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3992 extern struct JavaVM_ main_vm;
3993 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3994
3995 // Find the Agent_OnUnload function.
3996 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3997 os::find_agent_function(agent,
3998 false,
3999 on_unload_symbols,
4000 num_symbol_entries));
4001
4002 // Invoke the Agent_OnUnload function
4003 if (unload_entry != NULL) {
4004 JavaThread* thread = JavaThread::current();
4005 ThreadToNativeFromVM ttn(thread);
4006 HandleMark hm(thread);
4007 (*unload_entry)(&main_vm);
4008 }
4009 }
4010 }
4011
4012 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4013 // Invokes JVM_OnLoad
4014 void Threads::create_vm_init_libraries() {
4015 extern struct JavaVM_ main_vm;
4016 AgentLibrary* agent;
4017
4018 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4019 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4020
4021 if (on_load_entry != NULL) {
4022 // Invoke the JVM_OnLoad function
4023 JavaThread* thread = JavaThread::current();
4024 ThreadToNativeFromVM ttn(thread);
4025 HandleMark hm(thread);
4026 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4027 if (err != JNI_OK) {
4028 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4029 }
4030 } else {
4031 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4032 }
4033 }
4034 }
4035
4036 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4037 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4038
4039 JavaThread* java_thread = NULL;
4040 // Sequential search for now. Need to do better optimization later.
4041 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4042 oop tobj = thread->threadObj();
4043 if (!thread->is_exiting() &&
4044 tobj != NULL &&
4045 java_tid == java_lang_Thread::thread_id(tobj)) {
4046 java_thread = thread;
4047 break;
4048 }
4049 }
4050 return java_thread;
4051 }
4052
4053
4054 // Last thread running calls java.lang.Shutdown.shutdown()
4055 void JavaThread::invoke_shutdown_hooks() {
4056 HandleMark hm(this);
4057
4058 // We could get here with a pending exception, if so clear it now.
4059 if (this->has_pending_exception()) {
4060 this->clear_pending_exception();
4061 }
4062
4063 EXCEPTION_MARK;
4064 Klass* k =
4065 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4066 THREAD);
4067 if (k != NULL) {
4068 // SystemDictionary::resolve_or_null will return null if there was
4069 // an exception. If we cannot load the Shutdown class, just don't
4070 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4071 // and finalizers (if runFinalizersOnExit is set) won't be run.
4072 // Note that if a shutdown hook was registered or runFinalizersOnExit
4073 // was called, the Shutdown class would have already been loaded
4074 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4075 instanceKlassHandle shutdown_klass (THREAD, k);
4076 JavaValue result(T_VOID);
4077 JavaCalls::call_static(&result,
4078 shutdown_klass,
4079 vmSymbols::shutdown_method_name(),
4080 vmSymbols::void_method_signature(),
4081 THREAD);
4082 }
4083 CLEAR_PENDING_EXCEPTION;
4084 }
4085
4086 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4087 // the program falls off the end of main(). Another VM exit path is through
4088 // vm_exit() when the program calls System.exit() to return a value or when
4089 // there is a serious error in VM. The two shutdown paths are not exactly
4090 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4091 // and VM_Exit op at VM level.
4092 //
4093 // Shutdown sequence:
4094 // + Shutdown native memory tracking if it is on
4095 // + Wait until we are the last non-daemon thread to execute
4096 // <-- every thing is still working at this moment -->
4097 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4098 // shutdown hooks, run finalizers if finalization-on-exit
4099 // + Call before_exit(), prepare for VM exit
4100 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4101 // currently the only user of this mechanism is File.deleteOnExit())
4102 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4103 // post thread end and vm death events to JVMTI,
4104 // stop signal thread
4105 // + Call JavaThread::exit(), it will:
4106 // > release JNI handle blocks, remove stack guard pages
4107 // > remove this thread from Threads list
4108 // <-- no more Java code from this thread after this point -->
4109 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4110 // the compiler threads at safepoint
4111 // <-- do not use anything that could get blocked by Safepoint -->
4112 // + Disable tracing at JNI/JVM barriers
4113 // + Set _vm_exited flag for threads that are still running native code
4114 // + Delete this thread
4115 // + Call exit_globals()
4116 // > deletes tty
4117 // > deletes PerfMemory resources
4118 // + Return to caller
4119
4120 bool Threads::destroy_vm() {
4121 JavaThread* thread = JavaThread::current();
4122
4123 #ifdef ASSERT
4124 _vm_complete = false;
4125 #endif
4126 // Wait until we are the last non-daemon thread to execute
4127 { MutexLocker nu(Threads_lock);
4128 while (Threads::number_of_non_daemon_threads() > 1)
4129 // This wait should make safepoint checks, wait without a timeout,
4130 // and wait as a suspend-equivalent condition.
4131 //
4132 // Note: If the FlatProfiler is running and this thread is waiting
4133 // for another non-daemon thread to finish, then the FlatProfiler
4134 // is waiting for the external suspend request on this thread to
4135 // complete. wait_for_ext_suspend_completion() will eventually
4136 // timeout, but that takes time. Making this wait a suspend-
4137 // equivalent condition solves that timeout problem.
4138 //
4139 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4140 Mutex::_as_suspend_equivalent_flag);
4141 }
4142
4143 // Hang forever on exit if we are reporting an error.
4144 if (ShowMessageBoxOnError && is_error_reported()) {
4145 os::infinite_sleep();
4146 }
4147 os::wait_for_keypress_at_exit();
4148
4149 // run Java level shutdown hooks
4150 thread->invoke_shutdown_hooks();
4151
4152 before_exit(thread);
4153
4154 thread->exit(true);
4155
4156 // Stop VM thread.
4157 {
4158 // 4945125 The vm thread comes to a safepoint during exit.
4159 // GC vm_operations can get caught at the safepoint, and the
4160 // heap is unparseable if they are caught. Grab the Heap_lock
4161 // to prevent this. The GC vm_operations will not be able to
4162 // queue until after the vm thread is dead. After this point,
4163 // we'll never emerge out of the safepoint before the VM exits.
4164
4165 MutexLocker ml(Heap_lock);
4166
4167 VMThread::wait_for_vm_thread_exit();
4168 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4169 VMThread::destroy();
4170 }
4171
4172 // clean up ideal graph printers
4173 #if defined(COMPILER2) && !defined(PRODUCT)
4174 IdealGraphPrinter::clean_up();
4175 #endif
4176
4177 // Now, all Java threads are gone except daemon threads. Daemon threads
4178 // running Java code or in VM are stopped by the Safepoint. However,
4179 // daemon threads executing native code are still running. But they
4180 // will be stopped at native=>Java/VM barriers. Note that we can't
4181 // simply kill or suspend them, as it is inherently deadlock-prone.
4182
4183 VM_Exit::set_vm_exited();
4184
4185 notify_vm_shutdown();
4186
4187 delete thread;
4188
4189 #if INCLUDE_JVMCI
4190 if (JVMCICounterSize > 0) {
4191 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4192 }
4193 #endif
4194
4195 // exit_globals() will delete tty
4196 exit_globals();
4197
4198 LogConfiguration::finalize();
4199
4200 return true;
4201 }
4202
4203
4204 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4205 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4206 return is_supported_jni_version(version);
4207 }
4208
4209
4210 jboolean Threads::is_supported_jni_version(jint version) {
4211 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4212 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4213 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4214 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4215 if (version == JNI_VERSION_9) return JNI_TRUE;
4216 return JNI_FALSE;
4217 }
4218
4219
4220 void Threads::add(JavaThread* p, bool force_daemon) {
4221 // The threads lock must be owned at this point
4222 assert_locked_or_safepoint(Threads_lock);
4223
4224 // See the comment for this method in thread.hpp for its purpose and
4225 // why it is called here.
4226 p->initialize_queues();
4227 p->set_next(_thread_list);
4228 _thread_list = p;
4229 _number_of_threads++;
4230 oop threadObj = p->threadObj();
4231 bool daemon = true;
4232 // Bootstrapping problem: threadObj can be null for initial
4233 // JavaThread (or for threads attached via JNI)
4234 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4235 _number_of_non_daemon_threads++;
4236 daemon = false;
4237 }
4238
4239 ThreadService::add_thread(p, daemon);
4240
4241 // Possible GC point.
4242 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4243 }
4244
4245 void Threads::remove(JavaThread* p) {
4246 // Extra scope needed for Thread_lock, so we can check
4247 // that we do not remove thread without safepoint code notice
4248 { MutexLocker ml(Threads_lock);
4249
4250 assert(includes(p), "p must be present");
4251
4252 JavaThread* current = _thread_list;
4253 JavaThread* prev = NULL;
4254
4255 while (current != p) {
4256 prev = current;
4257 current = current->next();
4258 }
4259
4260 if (prev) {
4261 prev->set_next(current->next());
4262 } else {
4263 _thread_list = p->next();
4264 }
4265 _number_of_threads--;
4266 oop threadObj = p->threadObj();
4267 bool daemon = true;
4268 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4269 _number_of_non_daemon_threads--;
4270 daemon = false;
4271
4272 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4273 // on destroy_vm will wake up.
4274 if (number_of_non_daemon_threads() == 1) {
4275 Threads_lock->notify_all();
4276 }
4277 }
4278 ThreadService::remove_thread(p, daemon);
4279
4280 // Make sure that safepoint code disregard this thread. This is needed since
4281 // the thread might mess around with locks after this point. This can cause it
4282 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4283 // of this thread since it is removed from the queue.
4284 p->set_terminated_value();
4285 } // unlock Threads_lock
4286
4287 // Since Events::log uses a lock, we grab it outside the Threads_lock
4288 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4289 }
4290
4291 // Threads_lock must be held when this is called (or must be called during a safepoint)
4292 bool Threads::includes(JavaThread* p) {
4293 assert(Threads_lock->is_locked(), "sanity check");
4294 ALL_JAVA_THREADS(q) {
4295 if (q == p) {
4296 return true;
4297 }
4298 }
4299 return false;
4300 }
4301
4302 // Operations on the Threads list for GC. These are not explicitly locked,
4303 // but the garbage collector must provide a safe context for them to run.
4304 // In particular, these things should never be called when the Threads_lock
4305 // is held by some other thread. (Note: the Safepoint abstraction also
4306 // uses the Threads_lock to guarantee this property. It also makes sure that
4307 // all threads gets blocked when exiting or starting).
4308
4309 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4310 ALL_JAVA_THREADS(p) {
4311 p->oops_do(f, cf);
4312 }
4313 VMThread::vm_thread()->oops_do(f, cf);
4314 }
4315
4316 void Threads::change_thread_claim_parity() {
4317 // Set the new claim parity.
4318 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4319 "Not in range.");
4320 _thread_claim_parity++;
4321 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4322 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4323 "Not in range.");
4324 }
4325
4326 #ifdef ASSERT
4327 void Threads::assert_all_threads_claimed() {
4328 ALL_JAVA_THREADS(p) {
4329 const int thread_parity = p->oops_do_parity();
4330 assert((thread_parity == _thread_claim_parity),
4331 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4332 }
4333 }
4334 #endif // ASSERT
4335
4336 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4337 int cp = Threads::thread_claim_parity();
4338 ALL_JAVA_THREADS(p) {
4339 if (p->claim_oops_do(is_par, cp)) {
4340 p->oops_do(f, cf);
4341 }
4342 }
4343 VMThread* vmt = VMThread::vm_thread();
4344 if (vmt->claim_oops_do(is_par, cp)) {
4345 vmt->oops_do(f, cf);
4346 }
4347 }
4348
4349 #if INCLUDE_ALL_GCS
4350 // Used by ParallelScavenge
4351 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4352 ALL_JAVA_THREADS(p) {
4353 q->enqueue(new ThreadRootsTask(p));
4354 }
4355 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4356 }
4357
4358 // Used by Parallel Old
4359 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4360 ALL_JAVA_THREADS(p) {
4361 q->enqueue(new ThreadRootsMarkingTask(p));
4362 }
4363 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4364 }
4365 #endif // INCLUDE_ALL_GCS
4366
4367 void Threads::nmethods_do(CodeBlobClosure* cf) {
4368 ALL_JAVA_THREADS(p) {
4369 // This is used by the code cache sweeper to mark nmethods that are active
4370 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4371 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4372 if(!p->is_Code_cache_sweeper_thread()) {
4373 p->nmethods_do(cf);
4374 }
4375 }
4376 }
4377
4378 void Threads::metadata_do(void f(Metadata*)) {
4379 ALL_JAVA_THREADS(p) {
4380 p->metadata_do(f);
4381 }
4382 }
4383
4384 class ThreadHandlesClosure : public ThreadClosure {
4385 void (*_f)(Metadata*);
4386 public:
4387 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4388 virtual void do_thread(Thread* thread) {
4389 thread->metadata_handles_do(_f);
4390 }
4391 };
4392
4393 void Threads::metadata_handles_do(void f(Metadata*)) {
4394 // Only walk the Handles in Thread.
4395 ThreadHandlesClosure handles_closure(f);
4396 threads_do(&handles_closure);
4397 }
4398
4399 void Threads::deoptimized_wrt_marked_nmethods() {
4400 ALL_JAVA_THREADS(p) {
4401 p->deoptimized_wrt_marked_nmethods();
4402 }
4403 }
4404
4405
4406 // Get count Java threads that are waiting to enter the specified monitor.
4407 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4408 address monitor,
4409 bool doLock) {
4410 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4411 "must grab Threads_lock or be at safepoint");
4412 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4413
4414 int i = 0;
4415 {
4416 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4417 ALL_JAVA_THREADS(p) {
4418 if (!p->can_call_java()) continue;
4419
4420 address pending = (address)p->current_pending_monitor();
4421 if (pending == monitor) { // found a match
4422 if (i < count) result->append(p); // save the first count matches
4423 i++;
4424 }
4425 }
4426 }
4427 return result;
4428 }
4429
4430
4431 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4432 bool doLock) {
4433 assert(doLock ||
4434 Threads_lock->owned_by_self() ||
4435 SafepointSynchronize::is_at_safepoint(),
4436 "must grab Threads_lock or be at safepoint");
4437
4438 // NULL owner means not locked so we can skip the search
4439 if (owner == NULL) return NULL;
4440
4441 {
4442 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4443 ALL_JAVA_THREADS(p) {
4444 // first, see if owner is the address of a Java thread
4445 if (owner == (address)p) return p;
4446 }
4447 }
4448 // Cannot assert on lack of success here since this function may be
4449 // used by code that is trying to report useful problem information
4450 // like deadlock detection.
4451 if (UseHeavyMonitors) return NULL;
4452
4453 // If we didn't find a matching Java thread and we didn't force use of
4454 // heavyweight monitors, then the owner is the stack address of the
4455 // Lock Word in the owning Java thread's stack.
4456 //
4457 JavaThread* the_owner = NULL;
4458 {
4459 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4460 ALL_JAVA_THREADS(q) {
4461 if (q->is_lock_owned(owner)) {
4462 the_owner = q;
4463 break;
4464 }
4465 }
4466 }
4467 // cannot assert on lack of success here; see above comment
4468 return the_owner;
4469 }
4470
4471 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4472 void Threads::print_on(outputStream* st, bool print_stacks,
4473 bool internal_format, bool print_concurrent_locks) {
4474 char buf[32];
4475 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4476
4477 st->print_cr("Full thread dump %s (%s %s):",
4478 Abstract_VM_Version::vm_name(),
4479 Abstract_VM_Version::vm_release(),
4480 Abstract_VM_Version::vm_info_string());
4481 st->cr();
4482
4483 #if INCLUDE_SERVICES
4484 // Dump concurrent locks
4485 ConcurrentLocksDump concurrent_locks;
4486 if (print_concurrent_locks) {
4487 concurrent_locks.dump_at_safepoint();
4488 }
4489 #endif // INCLUDE_SERVICES
4490
4491 ALL_JAVA_THREADS(p) {
4492 ResourceMark rm;
4493 p->print_on(st);
4494 if (print_stacks) {
4495 if (internal_format) {
4496 p->trace_stack();
4497 } else {
4498 p->print_stack_on(st);
4499 }
4500 }
4501 st->cr();
4502 #if INCLUDE_SERVICES
4503 if (print_concurrent_locks) {
4504 concurrent_locks.print_locks_on(p, st);
4505 }
4506 #endif // INCLUDE_SERVICES
4507 }
4508
4509 VMThread::vm_thread()->print_on(st);
4510 st->cr();
4511 Universe::heap()->print_gc_threads_on(st);
4512 WatcherThread* wt = WatcherThread::watcher_thread();
4513 if (wt != NULL) {
4514 wt->print_on(st);
4515 st->cr();
4516 }
4517 st->flush();
4518 }
4519
4520 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4521 int buflen, bool* found_current) {
4522 if (this_thread != NULL) {
4523 bool is_current = (current == this_thread);
4524 *found_current = *found_current || is_current;
4525 st->print("%s", is_current ? "=>" : " ");
4526
4527 st->print(PTR_FORMAT, p2i(this_thread));
4528 st->print(" ");
4529 this_thread->print_on_error(st, buf, buflen);
4530 st->cr();
4531 }
4532 }
4533
4534 class PrintOnErrorClosure : public ThreadClosure {
4535 outputStream* _st;
4536 Thread* _current;
4537 char* _buf;
4538 int _buflen;
4539 bool* _found_current;
4540 public:
4541 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4542 int buflen, bool* found_current) :
4543 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4544
4545 virtual void do_thread(Thread* thread) {
4546 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4547 }
4548 };
4549
4550 // Threads::print_on_error() is called by fatal error handler. It's possible
4551 // that VM is not at safepoint and/or current thread is inside signal handler.
4552 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4553 // memory (even in resource area), it might deadlock the error handler.
4554 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4555 int buflen) {
4556 bool found_current = false;
4557 st->print_cr("Java Threads: ( => current thread )");
4558 ALL_JAVA_THREADS(thread) {
4559 print_on_error(thread, st, current, buf, buflen, &found_current);
4560 }
4561 st->cr();
4562
4563 st->print_cr("Other Threads:");
4564 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4565 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4566
4567 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4568 Universe::heap()->gc_threads_do(&print_closure);
4569
4570 if (!found_current) {
4571 st->cr();
4572 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4573 current->print_on_error(st, buf, buflen);
4574 st->cr();
4575 }
4576 st->cr();
4577 st->print_cr("Threads with active compile tasks:");
4578 print_threads_compiling(st, buf, buflen);
4579 }
4580
4581 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4582 ALL_JAVA_THREADS(thread) {
4583 if (thread->is_Compiler_thread()) {
4584 CompilerThread* ct = (CompilerThread*) thread;
4585 if (ct->task() != NULL) {
4586 thread->print_name_on_error(st, buf, buflen);
4587 ct->task()->print(st, NULL, true, true);
4588 }
4589 }
4590 }
4591 }
4592
4593
4594 // Internal SpinLock and Mutex
4595 // Based on ParkEvent
4596
4597 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4598 //
4599 // We employ SpinLocks _only for low-contention, fixed-length
4600 // short-duration critical sections where we're concerned
4601 // about native mutex_t or HotSpot Mutex:: latency.
4602 // The mux construct provides a spin-then-block mutual exclusion
4603 // mechanism.
4604 //
4605 // Testing has shown that contention on the ListLock guarding gFreeList
4606 // is common. If we implement ListLock as a simple SpinLock it's common
4607 // for the JVM to devolve to yielding with little progress. This is true
4608 // despite the fact that the critical sections protected by ListLock are
4609 // extremely short.
4610 //
4611 // TODO-FIXME: ListLock should be of type SpinLock.
4612 // We should make this a 1st-class type, integrated into the lock
4613 // hierarchy as leaf-locks. Critically, the SpinLock structure
4614 // should have sufficient padding to avoid false-sharing and excessive
4615 // cache-coherency traffic.
4616
4617
4618 typedef volatile int SpinLockT;
4619
4620 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4621 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4622 return; // normal fast-path return
4623 }
4624
4625 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4626 TEVENT(SpinAcquire - ctx);
4627 int ctr = 0;
4628 int Yields = 0;
4629 for (;;) {
4630 while (*adr != 0) {
4631 ++ctr;
4632 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4633 if (Yields > 5) {
4634 os::naked_short_sleep(1);
4635 } else {
4636 os::naked_yield();
4637 ++Yields;
4638 }
4639 } else {
4640 SpinPause();
4641 }
4642 }
4643 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4644 }
4645 }
4646
4647 void Thread::SpinRelease(volatile int * adr) {
4648 assert(*adr != 0, "invariant");
4649 OrderAccess::fence(); // guarantee at least release consistency.
4650 // Roach-motel semantics.
4651 // It's safe if subsequent LDs and STs float "up" into the critical section,
4652 // but prior LDs and STs within the critical section can't be allowed
4653 // to reorder or float past the ST that releases the lock.
4654 // Loads and stores in the critical section - which appear in program
4655 // order before the store that releases the lock - must also appear
4656 // before the store that releases the lock in memory visibility order.
4657 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4658 // the ST of 0 into the lock-word which releases the lock, so fence
4659 // more than covers this on all platforms.
4660 *adr = 0;
4661 }
4662
4663 // muxAcquire and muxRelease:
4664 //
4665 // * muxAcquire and muxRelease support a single-word lock-word construct.
4666 // The LSB of the word is set IFF the lock is held.
4667 // The remainder of the word points to the head of a singly-linked list
4668 // of threads blocked on the lock.
4669 //
4670 // * The current implementation of muxAcquire-muxRelease uses its own
4671 // dedicated Thread._MuxEvent instance. If we're interested in
4672 // minimizing the peak number of extant ParkEvent instances then
4673 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4674 // as certain invariants were satisfied. Specifically, care would need
4675 // to be taken with regards to consuming unpark() "permits".
4676 // A safe rule of thumb is that a thread would never call muxAcquire()
4677 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4678 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4679 // consume an unpark() permit intended for monitorenter, for instance.
4680 // One way around this would be to widen the restricted-range semaphore
4681 // implemented in park(). Another alternative would be to provide
4682 // multiple instances of the PlatformEvent() for each thread. One
4683 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4684 //
4685 // * Usage:
4686 // -- Only as leaf locks
4687 // -- for short-term locking only as muxAcquire does not perform
4688 // thread state transitions.
4689 //
4690 // Alternatives:
4691 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4692 // but with parking or spin-then-park instead of pure spinning.
4693 // * Use Taura-Oyama-Yonenzawa locks.
4694 // * It's possible to construct a 1-0 lock if we encode the lockword as
4695 // (List,LockByte). Acquire will CAS the full lockword while Release
4696 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4697 // acquiring threads use timers (ParkTimed) to detect and recover from
4698 // the stranding window. Thread/Node structures must be aligned on 256-byte
4699 // boundaries by using placement-new.
4700 // * Augment MCS with advisory back-link fields maintained with CAS().
4701 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4702 // The validity of the backlinks must be ratified before we trust the value.
4703 // If the backlinks are invalid the exiting thread must back-track through the
4704 // the forward links, which are always trustworthy.
4705 // * Add a successor indication. The LockWord is currently encoded as
4706 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4707 // to provide the usual futile-wakeup optimization.
4708 // See RTStt for details.
4709 // * Consider schedctl.sc_nopreempt to cover the critical section.
4710 //
4711
4712
4713 typedef volatile intptr_t MutexT; // Mux Lock-word
4714 enum MuxBits { LOCKBIT = 1 };
4715
4716 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4717 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4718 if (w == 0) return;
4719 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4720 return;
4721 }
4722
4723 TEVENT(muxAcquire - Contention);
4724 ParkEvent * const Self = Thread::current()->_MuxEvent;
4725 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4726 for (;;) {
4727 int its = (os::is_MP() ? 100 : 0) + 1;
4728
4729 // Optional spin phase: spin-then-park strategy
4730 while (--its >= 0) {
4731 w = *Lock;
4732 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4733 return;
4734 }
4735 }
4736
4737 Self->reset();
4738 Self->OnList = intptr_t(Lock);
4739 // The following fence() isn't _strictly necessary as the subsequent
4740 // CAS() both serializes execution and ratifies the fetched *Lock value.
4741 OrderAccess::fence();
4742 for (;;) {
4743 w = *Lock;
4744 if ((w & LOCKBIT) == 0) {
4745 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4746 Self->OnList = 0; // hygiene - allows stronger asserts
4747 return;
4748 }
4749 continue; // Interference -- *Lock changed -- Just retry
4750 }
4751 assert(w & LOCKBIT, "invariant");
4752 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4753 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4754 }
4755
4756 while (Self->OnList != 0) {
4757 Self->park();
4758 }
4759 }
4760 }
4761
4762 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4763 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4764 if (w == 0) return;
4765 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4766 return;
4767 }
4768
4769 TEVENT(muxAcquire - Contention);
4770 ParkEvent * ReleaseAfter = NULL;
4771 if (ev == NULL) {
4772 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4773 }
4774 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4775 for (;;) {
4776 guarantee(ev->OnList == 0, "invariant");
4777 int its = (os::is_MP() ? 100 : 0) + 1;
4778
4779 // Optional spin phase: spin-then-park strategy
4780 while (--its >= 0) {
4781 w = *Lock;
4782 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4783 if (ReleaseAfter != NULL) {
4784 ParkEvent::Release(ReleaseAfter);
4785 }
4786 return;
4787 }
4788 }
4789
4790 ev->reset();
4791 ev->OnList = intptr_t(Lock);
4792 // The following fence() isn't _strictly necessary as the subsequent
4793 // CAS() both serializes execution and ratifies the fetched *Lock value.
4794 OrderAccess::fence();
4795 for (;;) {
4796 w = *Lock;
4797 if ((w & LOCKBIT) == 0) {
4798 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4799 ev->OnList = 0;
4800 // We call ::Release while holding the outer lock, thus
4801 // artificially lengthening the critical section.
4802 // Consider deferring the ::Release() until the subsequent unlock(),
4803 // after we've dropped the outer lock.
4804 if (ReleaseAfter != NULL) {
4805 ParkEvent::Release(ReleaseAfter);
4806 }
4807 return;
4808 }
4809 continue; // Interference -- *Lock changed -- Just retry
4810 }
4811 assert(w & LOCKBIT, "invariant");
4812 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4813 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4814 }
4815
4816 while (ev->OnList != 0) {
4817 ev->park();
4818 }
4819 }
4820 }
4821
4822 // Release() must extract a successor from the list and then wake that thread.
4823 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4824 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4825 // Release() would :
4826 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4827 // (B) Extract a successor from the private list "in-hand"
4828 // (C) attempt to CAS() the residual back into *Lock over null.
4829 // If there were any newly arrived threads and the CAS() would fail.
4830 // In that case Release() would detach the RATs, re-merge the list in-hand
4831 // with the RATs and repeat as needed. Alternately, Release() might
4832 // detach and extract a successor, but then pass the residual list to the wakee.
4833 // The wakee would be responsible for reattaching and remerging before it
4834 // competed for the lock.
4835 //
4836 // Both "pop" and DMR are immune from ABA corruption -- there can be
4837 // multiple concurrent pushers, but only one popper or detacher.
4838 // This implementation pops from the head of the list. This is unfair,
4839 // but tends to provide excellent throughput as hot threads remain hot.
4840 // (We wake recently run threads first).
4841 //
4842 // All paths through muxRelease() will execute a CAS.
4843 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4844 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4845 // executed within the critical section are complete and globally visible before the
4846 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4847 void Thread::muxRelease(volatile intptr_t * Lock) {
4848 for (;;) {
4849 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4850 assert(w & LOCKBIT, "invariant");
4851 if (w == LOCKBIT) return;
4852 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4853 assert(List != NULL, "invariant");
4854 assert(List->OnList == intptr_t(Lock), "invariant");
4855 ParkEvent * const nxt = List->ListNext;
4856 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4857
4858 // The following CAS() releases the lock and pops the head element.
4859 // The CAS() also ratifies the previously fetched lock-word value.
4860 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4861 continue;
4862 }
4863 List->OnList = 0;
4864 OrderAccess::fence();
4865 List->unpark();
4866 return;
4867 }
4868 }
4869
4870
4871 void Threads::verify() {
4872 ALL_JAVA_THREADS(p) {
4873 p->verify();
4874 }
4875 VMThread* thread = VMThread::vm_thread();
4876 if (thread != NULL) thread->verify();
4877 }