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.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/shenandoah/shenandoahConcurrentThread.hpp"
107 #include "gc/cms/concurrentMarkSweepThread.hpp"
108 #include "gc/g1/concurrentMarkThread.inline.hpp"
109 #include "gc/parallel/pcTasks.hpp"
110 #endif // INCLUDE_ALL_GCS
111 #if INCLUDE_JVMCI
112 #include "jvmci/jvmciCompiler.hpp"
113 #include "jvmci/jvmciRuntime.hpp"
114 #endif
115 #ifdef COMPILER1
116 #include "c1/c1_Compiler.hpp"
117 #endif
118 #ifdef COMPILER2
119 #include "opto/c2compiler.hpp"
120 #include "opto/idealGraphPrinter.hpp"
121 #endif
122 #if INCLUDE_RTM_OPT
123 #include "runtime/rtmLocking.hpp"
124 #endif
125
126 // Initialization after module runtime initialization
127 void universe_post_module_init(); // must happen after call_initPhase2
128
129 #ifdef DTRACE_ENABLED
130
131 // Only bother with this argument setup if dtrace is available
132
133 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
134 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
135
136 #define DTRACE_THREAD_PROBE(probe, javathread) \
137 { \
138 ResourceMark rm(this); \
139 int len = 0; \
140 const char* name = (javathread)->get_thread_name(); \
141 len = strlen(name); \
142 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
143 (char *) name, len, \
144 java_lang_Thread::thread_id((javathread)->threadObj()), \
145 (uintptr_t) (javathread)->osthread()->thread_id(), \
146 java_lang_Thread::is_daemon((javathread)->threadObj())); \
147 }
148
149 #else // ndef DTRACE_ENABLED
150
151 #define DTRACE_THREAD_PROBE(probe, javathread)
152
153 #endif // ndef DTRACE_ENABLED
154
155 #ifndef USE_LIBRARY_BASED_TLS_ONLY
156 // Current thread is maintained as a thread-local variable
157 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
158 #endif
159 // Class hierarchy
160 // - Thread
161 // - VMThread
162 // - WatcherThread
163 // - ConcurrentMarkSweepThread
164 // - JavaThread
165 // - CompilerThread
166
167 // ======= Thread ========
168 // Support for forcing alignment of thread objects for biased locking
169 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
170 if (UseBiasedLocking) {
171 const int alignment = markOopDesc::biased_lock_alignment;
172 size_t aligned_size = size + (alignment - sizeof(intptr_t));
173 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
174 : AllocateHeap(aligned_size, flags, CURRENT_PC,
175 AllocFailStrategy::RETURN_NULL);
176 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
177 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
178 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
179 "JavaThread alignment code overflowed allocated storage");
180 if (aligned_addr != real_malloc_addr) {
181 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
182 p2i(real_malloc_addr),
183 p2i(aligned_addr));
184 }
185 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
186 return aligned_addr;
187 } else {
188 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
189 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
190 }
191 }
192
193 void Thread::operator delete(void* p) {
194 if (UseBiasedLocking) {
195 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
196 FreeHeap(real_malloc_addr);
197 } else {
198 FreeHeap(p);
199 }
200 }
201
202
203 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
204 // JavaThread
205
206
207 Thread::Thread() {
208 // stack and get_thread
209 set_stack_base(NULL);
210 set_stack_size(0);
211 set_self_raw_id(0);
212 set_lgrp_id(-1);
213 DEBUG_ONLY(clear_suspendible_thread();)
214
215 // allocated data structures
216 set_osthread(NULL);
217 set_resource_area(new (mtThread)ResourceArea());
218 DEBUG_ONLY(_current_resource_mark = NULL;)
219 set_handle_area(new (mtThread) HandleArea(NULL));
220 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
221 set_active_handles(NULL);
222 set_free_handle_block(NULL);
223 set_last_handle_mark(NULL);
224
225 // This initial value ==> never claimed.
226 _oops_do_parity = 0;
227
228 // the handle mark links itself to last_handle_mark
229 new HandleMark(this);
230
231 // plain initialization
232 debug_only(_owned_locks = NULL;)
233 debug_only(_allow_allocation_count = 0;)
234 NOT_PRODUCT(_allow_safepoint_count = 0;)
235 NOT_PRODUCT(_skip_gcalot = false;)
236 _jvmti_env_iteration_count = 0;
237 set_allocated_bytes(0);
238 _vm_operation_started_count = 0;
239 _vm_operation_completed_count = 0;
240 _current_pending_monitor = NULL;
241 _current_pending_monitor_is_from_java = true;
242 _current_waiting_monitor = NULL;
243 _num_nested_signal = 0;
244 omFreeList = NULL;
245 omFreeCount = 0;
246 omFreeProvision = 32;
247 omInUseList = NULL;
248 omInUseCount = 0;
249
250 #ifdef ASSERT
251 _visited_for_critical_count = false;
252 #endif
253
254 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
255 Monitor::_safepoint_check_sometimes);
256 _suspend_flags = 0;
257
258 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
259 _hashStateX = os::random();
260 _hashStateY = 842502087;
261 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
262 _hashStateW = 273326509;
263
264 _OnTrap = 0;
265 _schedctl = NULL;
266 _Stalled = 0;
267 _TypeTag = 0x2BAD;
268
269 // Many of the following fields are effectively final - immutable
270 // Note that nascent threads can't use the Native Monitor-Mutex
271 // construct until the _MutexEvent is initialized ...
272 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
273 // we might instead use a stack of ParkEvents that we could provision on-demand.
274 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
275 // and ::Release()
276 _ParkEvent = ParkEvent::Allocate(this);
277 _SleepEvent = ParkEvent::Allocate(this);
278 _MutexEvent = ParkEvent::Allocate(this);
279 _MuxEvent = ParkEvent::Allocate(this);
280
281 #ifdef CHECK_UNHANDLED_OOPS
282 if (CheckUnhandledOops) {
283 _unhandled_oops = new UnhandledOops(this);
284 }
285 #endif // CHECK_UNHANDLED_OOPS
286 #ifdef ASSERT
287 if (UseBiasedLocking) {
288 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
289 assert(this == _real_malloc_address ||
290 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
291 "bug in forced alignment of thread objects");
292 }
293 #endif // ASSERT
294 }
295
296 void Thread::initialize_thread_current() {
297 #ifndef USE_LIBRARY_BASED_TLS_ONLY
298 assert(_thr_current == NULL, "Thread::current already initialized");
299 _thr_current = this;
300 #endif
301 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
302 ThreadLocalStorage::set_thread(this);
303 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
304 }
305
306 void Thread::clear_thread_current() {
307 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
308 #ifndef USE_LIBRARY_BASED_TLS_ONLY
309 _thr_current = NULL;
310 #endif
311 ThreadLocalStorage::set_thread(NULL);
312 }
313
314 void Thread::record_stack_base_and_size() {
315 set_stack_base(os::current_stack_base());
316 set_stack_size(os::current_stack_size());
317 // CR 7190089: on Solaris, primordial thread's stack is adjusted
318 // in initialize_thread(). Without the adjustment, stack size is
319 // incorrect if stack is set to unlimited (ulimit -s unlimited).
320 // So far, only Solaris has real implementation of initialize_thread().
321 //
322 // set up any platform-specific state.
323 os::initialize_thread(this);
324
325 // Set stack limits after thread is initialized.
326 if (is_Java_thread()) {
327 ((JavaThread*) this)->set_stack_overflow_limit();
328 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
329 }
330 #if INCLUDE_NMT
331 // record thread's native stack, stack grows downward
332 MemTracker::record_thread_stack(stack_end(), stack_size());
333 #endif // INCLUDE_NMT
334 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
335 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
336 os::current_thread_id(), p2i(stack_base() - stack_size()),
337 p2i(stack_base()), stack_size()/1024);
338 }
339
340
341 Thread::~Thread() {
342 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
343 ObjectSynchronizer::omFlush(this);
344
345 EVENT_THREAD_DESTRUCT(this);
346
347 // stack_base can be NULL if the thread is never started or exited before
348 // record_stack_base_and_size called. Although, we would like to ensure
349 // that all started threads do call record_stack_base_and_size(), there is
350 // not proper way to enforce that.
351 #if INCLUDE_NMT
352 if (_stack_base != NULL) {
353 MemTracker::release_thread_stack(stack_end(), stack_size());
354 #ifdef ASSERT
355 set_stack_base(NULL);
356 #endif
357 }
358 #endif // INCLUDE_NMT
359
360 // deallocate data structures
361 delete resource_area();
362 // since the handle marks are using the handle area, we have to deallocated the root
363 // handle mark before deallocating the thread's handle area,
364 assert(last_handle_mark() != NULL, "check we have an element");
365 delete last_handle_mark();
366 assert(last_handle_mark() == NULL, "check we have reached the end");
367
368 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
369 // We NULL out the fields for good hygiene.
370 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
371 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
372 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
373 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
374
375 delete handle_area();
376 delete metadata_handles();
377
378 // SR_handler uses this as a termination indicator -
379 // needs to happen before os::free_thread()
380 delete _SR_lock;
381 _SR_lock = NULL;
382
383 // osthread() can be NULL, if creation of thread failed.
384 if (osthread() != NULL) os::free_thread(osthread());
385
386 // clear Thread::current if thread is deleting itself.
387 // Needed to ensure JNI correctly detects non-attached threads.
388 if (this == Thread::current()) {
389 clear_thread_current();
390 }
391
392 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
393 }
394
395 // NOTE: dummy function for assertion purpose.
396 void Thread::run() {
397 ShouldNotReachHere();
398 }
399
400 #ifdef ASSERT
401 // Private method to check for dangling thread pointer
402 void check_for_dangling_thread_pointer(Thread *thread) {
403 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
404 "possibility of dangling Thread pointer");
405 }
406 #endif
407
408 ThreadPriority Thread::get_priority(const Thread* const thread) {
409 ThreadPriority priority;
410 // Can return an error!
411 (void)os::get_priority(thread, priority);
412 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
413 return priority;
414 }
415
416 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
417 debug_only(check_for_dangling_thread_pointer(thread);)
418 // Can return an error!
419 (void)os::set_priority(thread, priority);
420 }
421
422
423 void Thread::start(Thread* thread) {
424 // Start is different from resume in that its safety is guaranteed by context or
425 // being called from a Java method synchronized on the Thread object.
426 if (!DisableStartThread) {
427 if (thread->is_Java_thread()) {
428 // Initialize the thread state to RUNNABLE before starting this thread.
429 // Can not set it after the thread started because we do not know the
430 // exact thread state at that time. It could be in MONITOR_WAIT or
431 // in SLEEPING or some other state.
432 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
433 java_lang_Thread::RUNNABLE);
434 }
435 os::start_thread(thread);
436 }
437 }
438
439 // Enqueue a VM_Operation to do the job for us - sometime later
440 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
441 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
442 VMThread::execute(vm_stop);
443 }
444
445
446 // Check if an external suspend request has completed (or has been
447 // cancelled). Returns true if the thread is externally suspended and
448 // false otherwise.
449 //
450 // The bits parameter returns information about the code path through
451 // the routine. Useful for debugging:
452 //
453 // set in is_ext_suspend_completed():
454 // 0x00000001 - routine was entered
455 // 0x00000010 - routine return false at end
456 // 0x00000100 - thread exited (return false)
457 // 0x00000200 - suspend request cancelled (return false)
458 // 0x00000400 - thread suspended (return true)
459 // 0x00001000 - thread is in a suspend equivalent state (return true)
460 // 0x00002000 - thread is native and walkable (return true)
461 // 0x00004000 - thread is native_trans and walkable (needed retry)
462 //
463 // set in wait_for_ext_suspend_completion():
464 // 0x00010000 - routine was entered
465 // 0x00020000 - suspend request cancelled before loop (return false)
466 // 0x00040000 - thread suspended before loop (return true)
467 // 0x00080000 - suspend request cancelled in loop (return false)
468 // 0x00100000 - thread suspended in loop (return true)
469 // 0x00200000 - suspend not completed during retry loop (return false)
470
471 // Helper class for tracing suspend wait debug bits.
472 //
473 // 0x00000100 indicates that the target thread exited before it could
474 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
475 // 0x00080000 each indicate a cancelled suspend request so they don't
476 // count as wait failures either.
477 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
478
479 class TraceSuspendDebugBits : public StackObj {
480 private:
481 JavaThread * jt;
482 bool is_wait;
483 bool called_by_wait; // meaningful when !is_wait
484 uint32_t * bits;
485
486 public:
487 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
488 uint32_t *_bits) {
489 jt = _jt;
490 is_wait = _is_wait;
491 called_by_wait = _called_by_wait;
492 bits = _bits;
493 }
494
495 ~TraceSuspendDebugBits() {
496 if (!is_wait) {
497 #if 1
498 // By default, don't trace bits for is_ext_suspend_completed() calls.
499 // That trace is very chatty.
500 return;
501 #else
502 if (!called_by_wait) {
503 // If tracing for is_ext_suspend_completed() is enabled, then only
504 // trace calls to it from wait_for_ext_suspend_completion()
505 return;
506 }
507 #endif
508 }
509
510 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
511 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
512 MutexLocker ml(Threads_lock); // needed for get_thread_name()
513 ResourceMark rm;
514
515 tty->print_cr(
516 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
517 jt->get_thread_name(), *bits);
518
519 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
520 }
521 }
522 }
523 };
524 #undef DEBUG_FALSE_BITS
525
526
527 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
528 uint32_t *bits) {
529 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
530
531 bool did_trans_retry = false; // only do thread_in_native_trans retry once
532 bool do_trans_retry; // flag to force the retry
533
534 *bits |= 0x00000001;
535
536 do {
537 do_trans_retry = false;
538
539 if (is_exiting()) {
540 // Thread is in the process of exiting. This is always checked
541 // first to reduce the risk of dereferencing a freed JavaThread.
542 *bits |= 0x00000100;
543 return false;
544 }
545
546 if (!is_external_suspend()) {
547 // Suspend request is cancelled. This is always checked before
548 // is_ext_suspended() to reduce the risk of a rogue resume
549 // confusing the thread that made the suspend request.
550 *bits |= 0x00000200;
551 return false;
552 }
553
554 if (is_ext_suspended()) {
555 // thread is suspended
556 *bits |= 0x00000400;
557 return true;
558 }
559
560 // Now that we no longer do hard suspends of threads running
561 // native code, the target thread can be changing thread state
562 // while we are in this routine:
563 //
564 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
565 //
566 // We save a copy of the thread state as observed at this moment
567 // and make our decision about suspend completeness based on the
568 // copy. This closes the race where the thread state is seen as
569 // _thread_in_native_trans in the if-thread_blocked check, but is
570 // seen as _thread_blocked in if-thread_in_native_trans check.
571 JavaThreadState save_state = thread_state();
572
573 if (save_state == _thread_blocked && is_suspend_equivalent()) {
574 // If the thread's state is _thread_blocked and this blocking
575 // condition is known to be equivalent to a suspend, then we can
576 // consider the thread to be externally suspended. This means that
577 // the code that sets _thread_blocked has been modified to do
578 // self-suspension if the blocking condition releases. We also
579 // used to check for CONDVAR_WAIT here, but that is now covered by
580 // the _thread_blocked with self-suspension check.
581 //
582 // Return true since we wouldn't be here unless there was still an
583 // external suspend request.
584 *bits |= 0x00001000;
585 return true;
586 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
587 // Threads running native code will self-suspend on native==>VM/Java
588 // transitions. If its stack is walkable (should always be the case
589 // unless this function is called before the actual java_suspend()
590 // call), then the wait is done.
591 *bits |= 0x00002000;
592 return true;
593 } else if (!called_by_wait && !did_trans_retry &&
594 save_state == _thread_in_native_trans &&
595 frame_anchor()->walkable()) {
596 // The thread is transitioning from thread_in_native to another
597 // thread state. check_safepoint_and_suspend_for_native_trans()
598 // will force the thread to self-suspend. If it hasn't gotten
599 // there yet we may have caught the thread in-between the native
600 // code check above and the self-suspend. Lucky us. If we were
601 // called by wait_for_ext_suspend_completion(), then it
602 // will be doing the retries so we don't have to.
603 //
604 // Since we use the saved thread state in the if-statement above,
605 // there is a chance that the thread has already transitioned to
606 // _thread_blocked by the time we get here. In that case, we will
607 // make a single unnecessary pass through the logic below. This
608 // doesn't hurt anything since we still do the trans retry.
609
610 *bits |= 0x00004000;
611
612 // Once the thread leaves thread_in_native_trans for another
613 // thread state, we break out of this retry loop. We shouldn't
614 // need this flag to prevent us from getting back here, but
615 // sometimes paranoia is good.
616 did_trans_retry = true;
617
618 // We wait for the thread to transition to a more usable state.
619 for (int i = 1; i <= SuspendRetryCount; i++) {
620 // We used to do an "os::yield_all(i)" call here with the intention
621 // that yielding would increase on each retry. However, the parameter
622 // is ignored on Linux which means the yield didn't scale up. Waiting
623 // on the SR_lock below provides a much more predictable scale up for
624 // the delay. It also provides a simple/direct point to check for any
625 // safepoint requests from the VMThread
626
627 // temporarily drops SR_lock while doing wait with safepoint check
628 // (if we're a JavaThread - the WatcherThread can also call this)
629 // and increase delay with each retry
630 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
631
632 // check the actual thread state instead of what we saved above
633 if (thread_state() != _thread_in_native_trans) {
634 // the thread has transitioned to another thread state so
635 // try all the checks (except this one) one more time.
636 do_trans_retry = true;
637 break;
638 }
639 } // end retry loop
640
641
642 }
643 } while (do_trans_retry);
644
645 *bits |= 0x00000010;
646 return false;
647 }
648
649 // Wait for an external suspend request to complete (or be cancelled).
650 // Returns true if the thread is externally suspended and false otherwise.
651 //
652 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
653 uint32_t *bits) {
654 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
655 false /* !called_by_wait */, bits);
656
657 // local flag copies to minimize SR_lock hold time
658 bool is_suspended;
659 bool pending;
660 uint32_t reset_bits;
661
662 // set a marker so is_ext_suspend_completed() knows we are the caller
663 *bits |= 0x00010000;
664
665 // We use reset_bits to reinitialize the bits value at the top of
666 // each retry loop. This allows the caller to make use of any
667 // unused bits for their own marking purposes.
668 reset_bits = *bits;
669
670 {
671 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
672 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
673 delay, bits);
674 pending = is_external_suspend();
675 }
676 // must release SR_lock to allow suspension to complete
677
678 if (!pending) {
679 // A cancelled suspend request is the only false return from
680 // is_ext_suspend_completed() that keeps us from entering the
681 // retry loop.
682 *bits |= 0x00020000;
683 return false;
684 }
685
686 if (is_suspended) {
687 *bits |= 0x00040000;
688 return true;
689 }
690
691 for (int i = 1; i <= retries; i++) {
692 *bits = reset_bits; // reinit to only track last retry
693
694 // We used to do an "os::yield_all(i)" call here with the intention
695 // that yielding would increase on each retry. However, the parameter
696 // is ignored on Linux which means the yield didn't scale up. Waiting
697 // on the SR_lock below provides a much more predictable scale up for
698 // the delay. It also provides a simple/direct point to check for any
699 // safepoint requests from the VMThread
700
701 {
702 MutexLocker ml(SR_lock());
703 // wait with safepoint check (if we're a JavaThread - the WatcherThread
704 // can also call this) and increase delay with each retry
705 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
706
707 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
708 delay, bits);
709
710 // It is possible for the external suspend request to be cancelled
711 // (by a resume) before the actual suspend operation is completed.
712 // Refresh our local copy to see if we still need to wait.
713 pending = is_external_suspend();
714 }
715
716 if (!pending) {
717 // A cancelled suspend request is the only false return from
718 // is_ext_suspend_completed() that keeps us from staying in the
719 // retry loop.
720 *bits |= 0x00080000;
721 return false;
722 }
723
724 if (is_suspended) {
725 *bits |= 0x00100000;
726 return true;
727 }
728 } // end retry loop
729
730 // thread did not suspend after all our retries
731 *bits |= 0x00200000;
732 return false;
733 }
734
735 #ifndef PRODUCT
736 void JavaThread::record_jump(address target, address instr, const char* file,
737 int line) {
738
739 // This should not need to be atomic as the only way for simultaneous
740 // updates is via interrupts. Even then this should be rare or non-existent
741 // and we don't care that much anyway.
742
743 int index = _jmp_ring_index;
744 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
745 _jmp_ring[index]._target = (intptr_t) target;
746 _jmp_ring[index]._instruction = (intptr_t) instr;
747 _jmp_ring[index]._file = file;
748 _jmp_ring[index]._line = line;
749 }
750 #endif // PRODUCT
751
752 // Called by flat profiler
753 // Callers have already called wait_for_ext_suspend_completion
754 // The assertion for that is currently too complex to put here:
755 bool JavaThread::profile_last_Java_frame(frame* _fr) {
756 bool gotframe = false;
757 // self suspension saves needed state.
758 if (has_last_Java_frame() && _anchor.walkable()) {
759 *_fr = pd_last_frame();
760 gotframe = true;
761 }
762 return gotframe;
763 }
764
765 void Thread::interrupt(Thread* thread) {
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 os::interrupt(thread);
768 }
769
770 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
771 debug_only(check_for_dangling_thread_pointer(thread);)
772 // Note: If clear_interrupted==false, this simply fetches and
773 // returns the value of the field osthread()->interrupted().
774 return os::is_interrupted(thread, clear_interrupted);
775 }
776
777
778 // GC Support
779 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
780 jint thread_parity = _oops_do_parity;
781 if (thread_parity != strong_roots_parity) {
782 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
783 if (res == thread_parity) {
784 return true;
785 } else {
786 guarantee(res == strong_roots_parity, "Or else what?");
787 return false;
788 }
789 }
790 return false;
791 }
792
793 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
794 active_handles()->oops_do(f);
795 // Do oop for ThreadShadow
796 f->do_oop((oop*)&_pending_exception);
797 handle_area()->oops_do(f);
798 }
799
800 void Thread::metadata_handles_do(void f(Metadata*)) {
801 // Only walk the Handles in Thread.
802 if (metadata_handles() != NULL) {
803 for (int i = 0; i< metadata_handles()->length(); i++) {
804 f(metadata_handles()->at(i));
805 }
806 }
807 }
808
809 void Thread::print_on(outputStream* st) const {
810 // get_priority assumes osthread initialized
811 if (osthread() != NULL) {
812 int os_prio;
813 if (os::get_native_priority(this, &os_prio) == OS_OK) {
814 st->print("os_prio=%d ", os_prio);
815 }
816 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
817 ext().print_on(st);
818 osthread()->print_on(st);
819 }
820 debug_only(if (WizardMode) print_owned_locks_on(st);)
821 }
822
823 // Thread::print_on_error() is called by fatal error handler. Don't use
824 // any lock or allocate memory.
825 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
826 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
827
828 if (is_VM_thread()) { st->print("VMThread"); }
829 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
830 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
831 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
832 else { st->print("Thread"); }
833
834 if (is_Named_thread()) {
835 st->print(" \"%s\"", name());
836 }
837
838 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
839 p2i(stack_end()), p2i(stack_base()));
840
841 if (osthread()) {
842 st->print(" [id=%d]", osthread()->thread_id());
843 }
844 }
845
846 #ifdef ASSERT
847 void Thread::print_owned_locks_on(outputStream* st) const {
848 Monitor *cur = _owned_locks;
849 if (cur == NULL) {
850 st->print(" (no locks) ");
851 } else {
852 st->print_cr(" Locks owned:");
853 while (cur) {
854 cur->print_on(st);
855 cur = cur->next();
856 }
857 }
858 }
859
860 static int ref_use_count = 0;
861
862 bool Thread::owns_locks_but_compiled_lock() const {
863 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
864 if (cur != Compile_lock) return true;
865 }
866 return false;
867 }
868
869
870 #endif
871
872 #ifndef PRODUCT
873
874 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
875 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
876 // no threads which allow_vm_block's are held
877 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
878 // Check if current thread is allowed to block at a safepoint
879 if (!(_allow_safepoint_count == 0)) {
880 fatal("Possible safepoint reached by thread that does not allow it");
881 }
882 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
883 fatal("LEAF method calling lock?");
884 }
885
886 #ifdef ASSERT
887 if (potential_vm_operation && is_Java_thread()
888 && !Universe::is_bootstrapping()) {
889 // Make sure we do not hold any locks that the VM thread also uses.
890 // This could potentially lead to deadlocks
891 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
892 // Threads_lock is special, since the safepoint synchronization will not start before this is
893 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
894 // since it is used to transfer control between JavaThreads and the VMThread
895 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
896 if ((cur->allow_vm_block() &&
897 cur != Threads_lock &&
898 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
899 cur != VMOperationRequest_lock &&
900 cur != VMOperationQueue_lock) ||
901 cur->rank() == Mutex::special) {
902 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
903 }
904 }
905 }
906
907 if (GCALotAtAllSafepoints) {
908 // We could enter a safepoint here and thus have a gc
909 InterfaceSupport::check_gc_alot();
910 }
911 #endif
912 }
913 #endif
914
915 bool Thread::is_in_stack(address adr) const {
916 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
917 address end = os::current_stack_pointer();
918 // Allow non Java threads to call this without stack_base
919 if (_stack_base == NULL) return true;
920 if (stack_base() >= adr && adr >= end) return true;
921
922 return false;
923 }
924
925 bool Thread::is_in_usable_stack(address adr) const {
926 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
927 size_t usable_stack_size = _stack_size - stack_guard_size;
928
929 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
930 }
931
932
933 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
934 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
935 // used for compilation in the future. If that change is made, the need for these methods
936 // should be revisited, and they should be removed if possible.
937
938 bool Thread::is_lock_owned(address adr) const {
939 return on_local_stack(adr);
940 }
941
942 bool Thread::set_as_starting_thread() {
943 // NOTE: this must be called inside the main thread.
944 return os::create_main_thread((JavaThread*)this);
945 }
946
947 static void initialize_class(Symbol* class_name, TRAPS) {
948 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
949 InstanceKlass::cast(klass)->initialize(CHECK);
950 }
951
952
953 // Creates the initial ThreadGroup
954 static Handle create_initial_thread_group(TRAPS) {
955 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
956 instanceKlassHandle klass (THREAD, k);
957
958 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
959 {
960 JavaValue result(T_VOID);
961 JavaCalls::call_special(&result,
962 system_instance,
963 klass,
964 vmSymbols::object_initializer_name(),
965 vmSymbols::void_method_signature(),
966 CHECK_NH);
967 }
968 Universe::set_system_thread_group(system_instance());
969
970 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
971 {
972 JavaValue result(T_VOID);
973 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
974 JavaCalls::call_special(&result,
975 main_instance,
976 klass,
977 vmSymbols::object_initializer_name(),
978 vmSymbols::threadgroup_string_void_signature(),
979 system_instance,
980 string,
981 CHECK_NH);
982 }
983 return main_instance;
984 }
985
986 // Creates the initial Thread
987 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
988 TRAPS) {
989 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
990 instanceKlassHandle klass (THREAD, k);
991 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
992
993 java_lang_Thread::set_thread(thread_oop(), thread);
994 java_lang_Thread::set_priority(thread_oop(), NormPriority);
995 thread->set_threadObj(thread_oop());
996
997 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
998
999 JavaValue result(T_VOID);
1000 JavaCalls::call_special(&result, thread_oop,
1001 klass,
1002 vmSymbols::object_initializer_name(),
1003 vmSymbols::threadgroup_string_void_signature(),
1004 thread_group,
1005 string,
1006 CHECK_NULL);
1007 return thread_oop();
1008 }
1009
1010 char java_runtime_name[128] = "";
1011 char java_runtime_version[128] = "";
1012
1013 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1014 static const char* get_java_runtime_name(TRAPS) {
1015 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1016 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1017 fieldDescriptor fd;
1018 bool found = k != NULL &&
1019 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1020 vmSymbols::string_signature(), &fd);
1021 if (found) {
1022 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1023 if (name_oop == NULL) {
1024 return NULL;
1025 }
1026 const char* name = java_lang_String::as_utf8_string(name_oop,
1027 java_runtime_name,
1028 sizeof(java_runtime_name));
1029 return name;
1030 } else {
1031 return NULL;
1032 }
1033 }
1034
1035 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1036 static const char* get_java_runtime_version(TRAPS) {
1037 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1038 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1039 fieldDescriptor fd;
1040 bool found = k != NULL &&
1041 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1042 vmSymbols::string_signature(), &fd);
1043 if (found) {
1044 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1045 if (name_oop == NULL) {
1046 return NULL;
1047 }
1048 const char* name = java_lang_String::as_utf8_string(name_oop,
1049 java_runtime_version,
1050 sizeof(java_runtime_version));
1051 return name;
1052 } else {
1053 return NULL;
1054 }
1055 }
1056
1057 // General purpose hook into Java code, run once when the VM is initialized.
1058 // The Java library method itself may be changed independently from the VM.
1059 static void call_postVMInitHook(TRAPS) {
1060 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1061 instanceKlassHandle klass (THREAD, k);
1062 if (klass.not_null()) {
1063 JavaValue result(T_VOID);
1064 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1065 vmSymbols::void_method_signature(),
1066 CHECK);
1067 }
1068 }
1069
1070 static void reset_vm_info_property(TRAPS) {
1071 // the vm info string
1072 ResourceMark rm(THREAD);
1073 const char *vm_info = VM_Version::vm_info_string();
1074
1075 // java.lang.System class
1076 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1077 instanceKlassHandle klass (THREAD, k);
1078
1079 // setProperty arguments
1080 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1081 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1082
1083 // return value
1084 JavaValue r(T_OBJECT);
1085
1086 // public static String setProperty(String key, String value);
1087 JavaCalls::call_static(&r,
1088 klass,
1089 vmSymbols::setProperty_name(),
1090 vmSymbols::string_string_string_signature(),
1091 key_str,
1092 value_str,
1093 CHECK);
1094 }
1095
1096
1097 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1098 bool daemon, TRAPS) {
1099 assert(thread_group.not_null(), "thread group should be specified");
1100 assert(threadObj() == NULL, "should only create Java thread object once");
1101
1102 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1103 instanceKlassHandle klass (THREAD, k);
1104 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1105
1106 java_lang_Thread::set_thread(thread_oop(), this);
1107 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1108 set_threadObj(thread_oop());
1109
1110 JavaValue result(T_VOID);
1111 if (thread_name != NULL) {
1112 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1113 // Thread gets assigned specified name and null target
1114 JavaCalls::call_special(&result,
1115 thread_oop,
1116 klass,
1117 vmSymbols::object_initializer_name(),
1118 vmSymbols::threadgroup_string_void_signature(),
1119 thread_group, // Argument 1
1120 name, // Argument 2
1121 THREAD);
1122 } else {
1123 // Thread gets assigned name "Thread-nnn" and null target
1124 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1125 JavaCalls::call_special(&result,
1126 thread_oop,
1127 klass,
1128 vmSymbols::object_initializer_name(),
1129 vmSymbols::threadgroup_runnable_void_signature(),
1130 thread_group, // Argument 1
1131 Handle(), // Argument 2
1132 THREAD);
1133 }
1134
1135
1136 if (daemon) {
1137 java_lang_Thread::set_daemon(thread_oop());
1138 }
1139
1140 if (HAS_PENDING_EXCEPTION) {
1141 return;
1142 }
1143
1144 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1145 Handle threadObj(THREAD, this->threadObj());
1146
1147 JavaCalls::call_special(&result,
1148 thread_group,
1149 group,
1150 vmSymbols::add_method_name(),
1151 vmSymbols::thread_void_signature(),
1152 threadObj, // Arg 1
1153 THREAD);
1154 }
1155
1156 // NamedThread -- non-JavaThread subclasses with multiple
1157 // uniquely named instances should derive from this.
1158 NamedThread::NamedThread() : Thread() {
1159 _name = NULL;
1160 _processed_thread = NULL;
1161 _gc_id = GCId::undefined();
1162 }
1163
1164 NamedThread::~NamedThread() {
1165 if (_name != NULL) {
1166 FREE_C_HEAP_ARRAY(char, _name);
1167 _name = NULL;
1168 }
1169 }
1170
1171 void NamedThread::set_name(const char* format, ...) {
1172 guarantee(_name == NULL, "Only get to set name once.");
1173 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1174 guarantee(_name != NULL, "alloc failure");
1175 va_list ap;
1176 va_start(ap, format);
1177 jio_vsnprintf(_name, max_name_len, format, ap);
1178 va_end(ap);
1179 }
1180
1181 void NamedThread::initialize_named_thread() {
1182 set_native_thread_name(name());
1183 }
1184
1185 void NamedThread::print_on(outputStream* st) const {
1186 st->print("\"%s\" ", name());
1187 Thread::print_on(st);
1188 st->cr();
1189 }
1190
1191
1192 // ======= WatcherThread ========
1193
1194 // The watcher thread exists to simulate timer interrupts. It should
1195 // be replaced by an abstraction over whatever native support for
1196 // timer interrupts exists on the platform.
1197
1198 WatcherThread* WatcherThread::_watcher_thread = NULL;
1199 bool WatcherThread::_startable = false;
1200 volatile bool WatcherThread::_should_terminate = false;
1201
1202 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1203 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1204 if (os::create_thread(this, os::watcher_thread)) {
1205 _watcher_thread = this;
1206
1207 // Set the watcher thread to the highest OS priority which should not be
1208 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1209 // is created. The only normal thread using this priority is the reference
1210 // handler thread, which runs for very short intervals only.
1211 // If the VMThread's priority is not lower than the WatcherThread profiling
1212 // will be inaccurate.
1213 os::set_priority(this, MaxPriority);
1214 if (!DisableStartThread) {
1215 os::start_thread(this);
1216 }
1217 }
1218 }
1219
1220 int WatcherThread::sleep() const {
1221 // The WatcherThread does not participate in the safepoint protocol
1222 // for the PeriodicTask_lock because it is not a JavaThread.
1223 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1224
1225 if (_should_terminate) {
1226 // check for termination before we do any housekeeping or wait
1227 return 0; // we did not sleep.
1228 }
1229
1230 // remaining will be zero if there are no tasks,
1231 // causing the WatcherThread to sleep until a task is
1232 // enrolled
1233 int remaining = PeriodicTask::time_to_wait();
1234 int time_slept = 0;
1235
1236 // we expect this to timeout - we only ever get unparked when
1237 // we should terminate or when a new task has been enrolled
1238 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1239
1240 jlong time_before_loop = os::javaTimeNanos();
1241
1242 while (true) {
1243 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1244 remaining);
1245 jlong now = os::javaTimeNanos();
1246
1247 if (remaining == 0) {
1248 // if we didn't have any tasks we could have waited for a long time
1249 // consider the time_slept zero and reset time_before_loop
1250 time_slept = 0;
1251 time_before_loop = now;
1252 } else {
1253 // need to recalculate since we might have new tasks in _tasks
1254 time_slept = (int) ((now - time_before_loop) / 1000000);
1255 }
1256
1257 // Change to task list or spurious wakeup of some kind
1258 if (timedout || _should_terminate) {
1259 break;
1260 }
1261
1262 remaining = PeriodicTask::time_to_wait();
1263 if (remaining == 0) {
1264 // Last task was just disenrolled so loop around and wait until
1265 // another task gets enrolled
1266 continue;
1267 }
1268
1269 remaining -= time_slept;
1270 if (remaining <= 0) {
1271 break;
1272 }
1273 }
1274
1275 return time_slept;
1276 }
1277
1278 void WatcherThread::run() {
1279 assert(this == watcher_thread(), "just checking");
1280
1281 this->record_stack_base_and_size();
1282 this->set_native_thread_name(this->name());
1283 this->set_active_handles(JNIHandleBlock::allocate_block());
1284 while (true) {
1285 assert(watcher_thread() == Thread::current(), "thread consistency check");
1286 assert(watcher_thread() == this, "thread consistency check");
1287
1288 // Calculate how long it'll be until the next PeriodicTask work
1289 // should be done, and sleep that amount of time.
1290 int time_waited = sleep();
1291
1292 if (is_error_reported()) {
1293 // A fatal error has happened, the error handler(VMError::report_and_die)
1294 // should abort JVM after creating an error log file. However in some
1295 // rare cases, the error handler itself might deadlock. Here we try to
1296 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1297 //
1298 // This code is in WatcherThread because WatcherThread wakes up
1299 // periodically so the fatal error handler doesn't need to do anything;
1300 // also because the WatcherThread is less likely to crash than other
1301 // threads.
1302
1303 for (;;) {
1304 if (!ShowMessageBoxOnError
1305 && (OnError == NULL || OnError[0] == '\0')
1306 && Arguments::abort_hook() == NULL) {
1307 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1308 fdStream err(defaultStream::output_fd());
1309 err.print_raw_cr("# [ timer expired, abort... ]");
1310 // skip atexit/vm_exit/vm_abort hooks
1311 os::die();
1312 }
1313
1314 // Wake up 5 seconds later, the fatal handler may reset OnError or
1315 // ShowMessageBoxOnError when it is ready to abort.
1316 os::sleep(this, 5 * 1000, false);
1317 }
1318 }
1319
1320 if (_should_terminate) {
1321 // check for termination before posting the next tick
1322 break;
1323 }
1324
1325 PeriodicTask::real_time_tick(time_waited);
1326 }
1327
1328 // Signal that it is terminated
1329 {
1330 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1331 _watcher_thread = NULL;
1332 Terminator_lock->notify();
1333 }
1334 }
1335
1336 void WatcherThread::start() {
1337 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1338
1339 if (watcher_thread() == NULL && _startable) {
1340 _should_terminate = false;
1341 // Create the single instance of WatcherThread
1342 new WatcherThread();
1343 }
1344 }
1345
1346 void WatcherThread::make_startable() {
1347 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1348 _startable = true;
1349 }
1350
1351 void WatcherThread::stop() {
1352 {
1353 // Follow normal safepoint aware lock enter protocol since the
1354 // WatcherThread is stopped by another JavaThread.
1355 MutexLocker ml(PeriodicTask_lock);
1356 _should_terminate = true;
1357
1358 WatcherThread* watcher = watcher_thread();
1359 if (watcher != NULL) {
1360 // unpark the WatcherThread so it can see that it should terminate
1361 watcher->unpark();
1362 }
1363 }
1364
1365 MutexLocker mu(Terminator_lock);
1366
1367 while (watcher_thread() != NULL) {
1368 // This wait should make safepoint checks, wait without a timeout,
1369 // and wait as a suspend-equivalent condition.
1370 //
1371 // Note: If the FlatProfiler is running, then this thread is waiting
1372 // for the WatcherThread to terminate and the WatcherThread, via the
1373 // FlatProfiler task, is waiting for the external suspend request on
1374 // this thread to complete. wait_for_ext_suspend_completion() will
1375 // eventually timeout, but that takes time. Making this wait a
1376 // suspend-equivalent condition solves that timeout problem.
1377 //
1378 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1379 Mutex::_as_suspend_equivalent_flag);
1380 }
1381 }
1382
1383 void WatcherThread::unpark() {
1384 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1385 PeriodicTask_lock->notify();
1386 }
1387
1388 void WatcherThread::print_on(outputStream* st) const {
1389 st->print("\"%s\" ", name());
1390 Thread::print_on(st);
1391 st->cr();
1392 }
1393
1394 // ======= JavaThread ========
1395
1396 #if INCLUDE_JVMCI
1397
1398 jlong* JavaThread::_jvmci_old_thread_counters;
1399
1400 bool jvmci_counters_include(JavaThread* thread) {
1401 oop threadObj = thread->threadObj();
1402 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1403 }
1404
1405 void JavaThread::collect_counters(typeArrayOop array) {
1406 if (JVMCICounterSize > 0) {
1407 MutexLocker tl(Threads_lock);
1408 for (int i = 0; i < array->length(); i++) {
1409 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1410 }
1411 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1412 if (jvmci_counters_include(tp)) {
1413 for (int i = 0; i < array->length(); i++) {
1414 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1415 }
1416 }
1417 }
1418 }
1419 }
1420
1421 #endif // INCLUDE_JVMCI
1422
1423 // A JavaThread is a normal Java thread
1424
1425 void JavaThread::initialize() {
1426 // Initialize fields
1427
1428 set_saved_exception_pc(NULL);
1429 set_threadObj(NULL);
1430 _anchor.clear();
1431 set_entry_point(NULL);
1432 set_jni_functions(jni_functions());
1433 set_callee_target(NULL);
1434 set_vm_result(NULL);
1435 set_vm_result_2(NULL);
1436 set_vframe_array_head(NULL);
1437 set_vframe_array_last(NULL);
1438 set_deferred_locals(NULL);
1439 set_deopt_mark(NULL);
1440 set_deopt_compiled_method(NULL);
1441 clear_must_deopt_id();
1442 set_monitor_chunks(NULL);
1443 set_next(NULL);
1444 set_thread_state(_thread_new);
1445 _terminated = _not_terminated;
1446 _privileged_stack_top = NULL;
1447 _array_for_gc = NULL;
1448 _suspend_equivalent = false;
1449 _in_deopt_handler = 0;
1450 _doing_unsafe_access = false;
1451 _stack_guard_state = stack_guard_unused;
1452 #if INCLUDE_JVMCI
1453 _pending_monitorenter = false;
1454 _pending_deoptimization = -1;
1455 _pending_failed_speculation = NULL;
1456 _pending_transfer_to_interpreter = false;
1457 _adjusting_comp_level = false;
1458 _jvmci._alternate_call_target = NULL;
1459 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1460 if (JVMCICounterSize > 0) {
1461 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1462 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1463 } else {
1464 _jvmci_counters = NULL;
1465 }
1466 #endif // INCLUDE_JVMCI
1467 _reserved_stack_activation = NULL; // stack base not known yet
1468 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1469 _exception_pc = 0;
1470 _exception_handler_pc = 0;
1471 _is_method_handle_return = 0;
1472 _jvmti_thread_state= NULL;
1473 _should_post_on_exceptions_flag = JNI_FALSE;
1474 _jvmti_get_loaded_classes_closure = NULL;
1475 _interp_only_mode = 0;
1476 _special_runtime_exit_condition = _no_async_condition;
1477 _pending_async_exception = NULL;
1478 _thread_stat = NULL;
1479 _thread_stat = new ThreadStatistics();
1480 _blocked_on_compilation = false;
1481 _jni_active_critical = 0;
1482 _pending_jni_exception_check_fn = NULL;
1483 _do_not_unlock_if_synchronized = false;
1484 _cached_monitor_info = NULL;
1485 _parker = Parker::Allocate(this);
1486
1487 #ifndef PRODUCT
1488 _jmp_ring_index = 0;
1489 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1490 record_jump(NULL, NULL, NULL, 0);
1491 }
1492 #endif // PRODUCT
1493
1494 set_thread_profiler(NULL);
1495 if (FlatProfiler::is_active()) {
1496 // This is where we would decide to either give each thread it's own profiler
1497 // or use one global one from FlatProfiler,
1498 // or up to some count of the number of profiled threads, etc.
1499 ThreadProfiler* pp = new ThreadProfiler();
1500 pp->engage();
1501 set_thread_profiler(pp);
1502 }
1503
1504 // Setup safepoint state info for this thread
1505 ThreadSafepointState::create(this);
1506
1507 debug_only(_java_call_counter = 0);
1508
1509 // JVMTI PopFrame support
1510 _popframe_condition = popframe_inactive;
1511 _popframe_preserved_args = NULL;
1512 _popframe_preserved_args_size = 0;
1513 _frames_to_pop_failed_realloc = 0;
1514
1515 pd_initialize();
1516 }
1517
1518 #if INCLUDE_ALL_GCS
1519 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1520 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1521 bool JavaThread::_evacuation_in_progress_global = false;
1522 #endif // INCLUDE_ALL_GCS
1523
1524 JavaThread::JavaThread(bool is_attaching_via_jni) :
1525 Thread()
1526 #if INCLUDE_ALL_GCS
1527 , _satb_mark_queue(&_satb_mark_queue_set),
1528 _dirty_card_queue(&_dirty_card_queue_set),
1529 _evacuation_in_progress(_evacuation_in_progress_global)
1530 #endif // INCLUDE_ALL_GCS
1531 {
1532 initialize();
1533 if (is_attaching_via_jni) {
1534 _jni_attach_state = _attaching_via_jni;
1535 } else {
1536 _jni_attach_state = _not_attaching_via_jni;
1537 }
1538 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1539 }
1540
1541 bool JavaThread::reguard_stack(address cur_sp) {
1542 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1543 && _stack_guard_state != stack_guard_reserved_disabled) {
1544 return true; // Stack already guarded or guard pages not needed.
1545 }
1546
1547 if (register_stack_overflow()) {
1548 // For those architectures which have separate register and
1549 // memory stacks, we must check the register stack to see if
1550 // it has overflowed.
1551 return false;
1552 }
1553
1554 // Java code never executes within the yellow zone: the latter is only
1555 // there to provoke an exception during stack banging. If java code
1556 // is executing there, either StackShadowPages should be larger, or
1557 // some exception code in c1, c2 or the interpreter isn't unwinding
1558 // when it should.
1559 guarantee(cur_sp > stack_reserved_zone_base(),
1560 "not enough space to reguard - increase StackShadowPages");
1561 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1562 enable_stack_yellow_reserved_zone();
1563 if (reserved_stack_activation() != stack_base()) {
1564 set_reserved_stack_activation(stack_base());
1565 }
1566 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1567 set_reserved_stack_activation(stack_base());
1568 enable_stack_reserved_zone();
1569 }
1570 return true;
1571 }
1572
1573 bool JavaThread::reguard_stack(void) {
1574 return reguard_stack(os::current_stack_pointer());
1575 }
1576
1577
1578 void JavaThread::block_if_vm_exited() {
1579 if (_terminated == _vm_exited) {
1580 // _vm_exited is set at safepoint, and Threads_lock is never released
1581 // we will block here forever
1582 Threads_lock->lock_without_safepoint_check();
1583 ShouldNotReachHere();
1584 }
1585 }
1586
1587
1588 // Remove this ifdef when C1 is ported to the compiler interface.
1589 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1590 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1591
1592 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1593 Thread()
1594 #if INCLUDE_ALL_GCS
1595 , _satb_mark_queue(&_satb_mark_queue_set),
1596 _dirty_card_queue(&_dirty_card_queue_set),
1597 _evacuation_in_progress(_evacuation_in_progress_global)
1598 #endif // INCLUDE_ALL_GCS
1599 {
1600 initialize();
1601 _jni_attach_state = _not_attaching_via_jni;
1602 set_entry_point(entry_point);
1603 // Create the native thread itself.
1604 // %note runtime_23
1605 os::ThreadType thr_type = os::java_thread;
1606 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1607 os::java_thread;
1608 os::create_thread(this, thr_type, stack_sz);
1609 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1610 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1611 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1612 // the exception consists of creating the exception object & initializing it, initialization
1613 // will leave the VM via a JavaCall and then all locks must be unlocked).
1614 //
1615 // The thread is still suspended when we reach here. Thread must be explicit started
1616 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1617 // by calling Threads:add. The reason why this is not done here, is because the thread
1618 // object must be fully initialized (take a look at JVM_Start)
1619 }
1620
1621 JavaThread::~JavaThread() {
1622
1623 // JSR166 -- return the parker to the free list
1624 Parker::Release(_parker);
1625 _parker = NULL;
1626
1627 // Free any remaining previous UnrollBlock
1628 vframeArray* old_array = vframe_array_last();
1629
1630 if (old_array != NULL) {
1631 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1632 old_array->set_unroll_block(NULL);
1633 delete old_info;
1634 delete old_array;
1635 }
1636
1637 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1638 if (deferred != NULL) {
1639 // This can only happen if thread is destroyed before deoptimization occurs.
1640 assert(deferred->length() != 0, "empty array!");
1641 do {
1642 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1643 deferred->remove_at(0);
1644 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1645 delete dlv;
1646 } while (deferred->length() != 0);
1647 delete deferred;
1648 }
1649
1650 // All Java related clean up happens in exit
1651 ThreadSafepointState::destroy(this);
1652 if (_thread_profiler != NULL) delete _thread_profiler;
1653 if (_thread_stat != NULL) delete _thread_stat;
1654
1655 #if INCLUDE_JVMCI
1656 if (JVMCICounterSize > 0) {
1657 if (jvmci_counters_include(this)) {
1658 for (int i = 0; i < JVMCICounterSize; i++) {
1659 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1660 }
1661 }
1662 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1663 }
1664 #endif // INCLUDE_JVMCI
1665 }
1666
1667
1668 // The first routine called by a new Java thread
1669 void JavaThread::run() {
1670 // initialize thread-local alloc buffer related fields
1671 this->initialize_tlab();
1672
1673 // used to test validity of stack trace backs
1674 this->record_base_of_stack_pointer();
1675
1676 // Record real stack base and size.
1677 this->record_stack_base_and_size();
1678
1679 this->create_stack_guard_pages();
1680
1681 this->cache_global_variables();
1682
1683 // Thread is now sufficient initialized to be handled by the safepoint code as being
1684 // in the VM. Change thread state from _thread_new to _thread_in_vm
1685 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1686
1687 assert(JavaThread::current() == this, "sanity check");
1688 assert(!Thread::current()->owns_locks(), "sanity check");
1689
1690 DTRACE_THREAD_PROBE(start, this);
1691
1692 // This operation might block. We call that after all safepoint checks for a new thread has
1693 // been completed.
1694 this->set_active_handles(JNIHandleBlock::allocate_block());
1695
1696 if (JvmtiExport::should_post_thread_life()) {
1697 JvmtiExport::post_thread_start(this);
1698 }
1699
1700 EventThreadStart event;
1701 if (event.should_commit()) {
1702 event.set_thread(THREAD_TRACE_ID(this));
1703 event.commit();
1704 }
1705
1706 // We call another function to do the rest so we are sure that the stack addresses used
1707 // from there will be lower than the stack base just computed
1708 thread_main_inner();
1709
1710 // Note, thread is no longer valid at this point!
1711 }
1712
1713
1714 void JavaThread::thread_main_inner() {
1715 assert(JavaThread::current() == this, "sanity check");
1716 assert(this->threadObj() != NULL, "just checking");
1717
1718 // Execute thread entry point unless this thread has a pending exception
1719 // or has been stopped before starting.
1720 // Note: Due to JVM_StopThread we can have pending exceptions already!
1721 if (!this->has_pending_exception() &&
1722 !java_lang_Thread::is_stillborn(this->threadObj())) {
1723 {
1724 ResourceMark rm(this);
1725 this->set_native_thread_name(this->get_thread_name());
1726 }
1727 HandleMark hm(this);
1728 this->entry_point()(this, this);
1729 }
1730
1731 DTRACE_THREAD_PROBE(stop, this);
1732
1733 this->exit(false);
1734 delete this;
1735 }
1736
1737
1738 static void ensure_join(JavaThread* thread) {
1739 // We do not need to grap the Threads_lock, since we are operating on ourself.
1740 Handle threadObj(thread, thread->threadObj());
1741 assert(threadObj.not_null(), "java thread object must exist");
1742 ObjectLocker lock(threadObj, thread);
1743 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1744 thread->clear_pending_exception();
1745 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1746 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1747 // Clear the native thread instance - this makes isAlive return false and allows the join()
1748 // to complete once we've done the notify_all below
1749 java_lang_Thread::set_thread(threadObj(), NULL);
1750 lock.notify_all(thread);
1751 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1752 thread->clear_pending_exception();
1753 }
1754
1755
1756 // For any new cleanup additions, please check to see if they need to be applied to
1757 // cleanup_failed_attach_current_thread as well.
1758 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1759 assert(this == JavaThread::current(), "thread consistency check");
1760
1761 HandleMark hm(this);
1762 Handle uncaught_exception(this, this->pending_exception());
1763 this->clear_pending_exception();
1764 Handle threadObj(this, this->threadObj());
1765 assert(threadObj.not_null(), "Java thread object should be created");
1766
1767 if (get_thread_profiler() != NULL) {
1768 get_thread_profiler()->disengage();
1769 ResourceMark rm;
1770 get_thread_profiler()->print(get_thread_name());
1771 }
1772
1773
1774 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1775 {
1776 EXCEPTION_MARK;
1777
1778 CLEAR_PENDING_EXCEPTION;
1779 }
1780 if (!destroy_vm) {
1781 if (uncaught_exception.not_null()) {
1782 EXCEPTION_MARK;
1783 // Call method Thread.dispatchUncaughtException().
1784 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1785 JavaValue result(T_VOID);
1786 JavaCalls::call_virtual(&result,
1787 threadObj, thread_klass,
1788 vmSymbols::dispatchUncaughtException_name(),
1789 vmSymbols::throwable_void_signature(),
1790 uncaught_exception,
1791 THREAD);
1792 if (HAS_PENDING_EXCEPTION) {
1793 ResourceMark rm(this);
1794 jio_fprintf(defaultStream::error_stream(),
1795 "\nException: %s thrown from the UncaughtExceptionHandler"
1796 " in thread \"%s\"\n",
1797 pending_exception()->klass()->external_name(),
1798 get_thread_name());
1799 CLEAR_PENDING_EXCEPTION;
1800 }
1801 }
1802
1803 // Called before the java thread exit since we want to read info
1804 // from java_lang_Thread object
1805 EventThreadEnd event;
1806 if (event.should_commit()) {
1807 event.set_thread(THREAD_TRACE_ID(this));
1808 event.commit();
1809 }
1810
1811 // Call after last event on thread
1812 EVENT_THREAD_EXIT(this);
1813
1814 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1815 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1816 // is deprecated anyhow.
1817 if (!is_Compiler_thread()) {
1818 int count = 3;
1819 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1820 EXCEPTION_MARK;
1821 JavaValue result(T_VOID);
1822 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1823 JavaCalls::call_virtual(&result,
1824 threadObj, thread_klass,
1825 vmSymbols::exit_method_name(),
1826 vmSymbols::void_method_signature(),
1827 THREAD);
1828 CLEAR_PENDING_EXCEPTION;
1829 }
1830 }
1831 // notify JVMTI
1832 if (JvmtiExport::should_post_thread_life()) {
1833 JvmtiExport::post_thread_end(this);
1834 }
1835
1836 // We have notified the agents that we are exiting, before we go on,
1837 // we must check for a pending external suspend request and honor it
1838 // in order to not surprise the thread that made the suspend request.
1839 while (true) {
1840 {
1841 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1842 if (!is_external_suspend()) {
1843 set_terminated(_thread_exiting);
1844 ThreadService::current_thread_exiting(this);
1845 break;
1846 }
1847 // Implied else:
1848 // Things get a little tricky here. We have a pending external
1849 // suspend request, but we are holding the SR_lock so we
1850 // can't just self-suspend. So we temporarily drop the lock
1851 // and then self-suspend.
1852 }
1853
1854 ThreadBlockInVM tbivm(this);
1855 java_suspend_self();
1856
1857 // We're done with this suspend request, but we have to loop around
1858 // and check again. Eventually we will get SR_lock without a pending
1859 // external suspend request and will be able to mark ourselves as
1860 // exiting.
1861 }
1862 // no more external suspends are allowed at this point
1863 } else {
1864 // before_exit() has already posted JVMTI THREAD_END events
1865 }
1866
1867 // Notify waiters on thread object. This has to be done after exit() is called
1868 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1869 // group should have the destroyed bit set before waiters are notified).
1870 ensure_join(this);
1871 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1872
1873 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1874 // held by this thread must be released. The spec does not distinguish
1875 // between JNI-acquired and regular Java monitors. We can only see
1876 // regular Java monitors here if monitor enter-exit matching is broken.
1877 //
1878 // Optionally release any monitors for regular JavaThread exits. This
1879 // is provided as a work around for any bugs in monitor enter-exit
1880 // matching. This can be expensive so it is not enabled by default.
1881 //
1882 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1883 // ObjectSynchronizer::release_monitors_owned_by_thread().
1884 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1885 // Sanity check even though JNI DetachCurrentThread() would have
1886 // returned JNI_ERR if there was a Java frame. JavaThread exit
1887 // should be done executing Java code by the time we get here.
1888 assert(!this->has_last_Java_frame(),
1889 "should not have a Java frame when detaching or exiting");
1890 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1891 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1892 }
1893
1894 // These things needs to be done while we are still a Java Thread. Make sure that thread
1895 // is in a consistent state, in case GC happens
1896 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1897
1898 if (active_handles() != NULL) {
1899 JNIHandleBlock* block = active_handles();
1900 set_active_handles(NULL);
1901 JNIHandleBlock::release_block(block);
1902 }
1903
1904 if (free_handle_block() != NULL) {
1905 JNIHandleBlock* block = free_handle_block();
1906 set_free_handle_block(NULL);
1907 JNIHandleBlock::release_block(block);
1908 }
1909
1910 // These have to be removed while this is still a valid thread.
1911 remove_stack_guard_pages();
1912
1913 if (UseTLAB) {
1914 tlab().make_parsable(true); // retire TLAB
1915 }
1916
1917 if (JvmtiEnv::environments_might_exist()) {
1918 JvmtiExport::cleanup_thread(this);
1919 }
1920
1921 // We must flush any deferred card marks before removing a thread from
1922 // the list of active threads.
1923 Universe::heap()->flush_deferred_store_barrier(this);
1924 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1925
1926 #if INCLUDE_ALL_GCS
1927 // We must flush the G1-related buffers before removing a thread
1928 // from the list of active threads. We must do this after any deferred
1929 // card marks have been flushed (above) so that any entries that are
1930 // added to the thread's dirty card queue as a result are not lost.
1931 if (UseG1GC || UseShenandoahGC) {
1932 flush_barrier_queues();
1933 }
1934 if (UseShenandoahGC && UseTLAB) {
1935 gclab().make_parsable(true);
1936 }
1937 #endif // INCLUDE_ALL_GCS
1938
1939 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1940 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1941 os::current_thread_id());
1942
1943 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1944 Threads::remove(this);
1945 }
1946
1947 #if INCLUDE_ALL_GCS
1948 // Flush G1-related queues.
1949 void JavaThread::flush_barrier_queues() {
1950 satb_mark_queue().flush();
1951 dirty_card_queue().flush();
1952 }
1953
1954 void JavaThread::initialize_queues() {
1955 assert(!SafepointSynchronize::is_at_safepoint(),
1956 "we should not be at a safepoint");
1957
1958 SATBMarkQueue& satb_queue = satb_mark_queue();
1959 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1960 // The SATB queue should have been constructed with its active
1961 // field set to false.
1962 assert(!satb_queue.is_active(), "SATB queue should not be active");
1963 assert(satb_queue.is_empty(), "SATB queue should be empty");
1964 // If we are creating the thread during a marking cycle, we should
1965 // set the active field of the SATB queue to true.
1966 if (satb_queue_set.is_active()) {
1967 satb_queue.set_active(true);
1968 }
1969
1970 DirtyCardQueue& dirty_queue = dirty_card_queue();
1971 // The dirty card queue should have been constructed with its
1972 // active field set to true.
1973 assert(dirty_queue.is_active(), "dirty card queue should be active");
1974
1975 _evacuation_in_progress = _evacuation_in_progress_global;
1976 }
1977
1978 bool JavaThread::evacuation_in_progress() const {
1979 return _evacuation_in_progress;
1980 }
1981
1982 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1983 _evacuation_in_progress = in_prog;
1984 }
1985
1986 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1987 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
1988 _evacuation_in_progress_global = in_prog;
1989 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) {
1990 t->set_evacuation_in_progress(in_prog);
1991 }
1992 }
1993 #endif // INCLUDE_ALL_GCS
1994
1995 void JavaThread::cleanup_failed_attach_current_thread() {
1996 if (get_thread_profiler() != NULL) {
1997 get_thread_profiler()->disengage();
1998 ResourceMark rm;
1999 get_thread_profiler()->print(get_thread_name());
2000 }
2001
2002 if (active_handles() != NULL) {
2003 JNIHandleBlock* block = active_handles();
2004 set_active_handles(NULL);
2005 JNIHandleBlock::release_block(block);
2006 }
2007
2008 if (free_handle_block() != NULL) {
2009 JNIHandleBlock* block = free_handle_block();
2010 set_free_handle_block(NULL);
2011 JNIHandleBlock::release_block(block);
2012 }
2013
2014 // These have to be removed while this is still a valid thread.
2015 remove_stack_guard_pages();
2016
2017 if (UseTLAB) {
2018 tlab().make_parsable(true); // retire TLAB, if any
2019 }
2020
2021 #if INCLUDE_ALL_GCS
2022 if (UseG1GC || UseShenandoahGC) {
2023 flush_barrier_queues();
2024 }
2025 if (UseShenandoahGC && UseTLAB) {
2026 gclab().make_parsable(true);
2027 }
2028 #endif // INCLUDE_ALL_GCS
2029
2030 Threads::remove(this);
2031 delete this;
2032 }
2033
2034
2035
2036
2037 JavaThread* JavaThread::active() {
2038 Thread* thread = Thread::current();
2039 if (thread->is_Java_thread()) {
2040 return (JavaThread*) thread;
2041 } else {
2042 assert(thread->is_VM_thread(), "this must be a vm thread");
2043 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2044 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2045 assert(ret->is_Java_thread(), "must be a Java thread");
2046 return ret;
2047 }
2048 }
2049
2050 bool JavaThread::is_lock_owned(address adr) const {
2051 if (Thread::is_lock_owned(adr)) return true;
2052
2053 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2054 if (chunk->contains(adr)) return true;
2055 }
2056
2057 return false;
2058 }
2059
2060
2061 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2062 chunk->set_next(monitor_chunks());
2063 set_monitor_chunks(chunk);
2064 }
2065
2066 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2067 guarantee(monitor_chunks() != NULL, "must be non empty");
2068 if (monitor_chunks() == chunk) {
2069 set_monitor_chunks(chunk->next());
2070 } else {
2071 MonitorChunk* prev = monitor_chunks();
2072 while (prev->next() != chunk) prev = prev->next();
2073 prev->set_next(chunk->next());
2074 }
2075 }
2076
2077 // JVM support.
2078
2079 // Note: this function shouldn't block if it's called in
2080 // _thread_in_native_trans state (such as from
2081 // check_special_condition_for_native_trans()).
2082 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2083
2084 if (has_last_Java_frame() && has_async_condition()) {
2085 // If we are at a polling page safepoint (not a poll return)
2086 // then we must defer async exception because live registers
2087 // will be clobbered by the exception path. Poll return is
2088 // ok because the call we a returning from already collides
2089 // with exception handling registers and so there is no issue.
2090 // (The exception handling path kills call result registers but
2091 // this is ok since the exception kills the result anyway).
2092
2093 if (is_at_poll_safepoint()) {
2094 // if the code we are returning to has deoptimized we must defer
2095 // the exception otherwise live registers get clobbered on the
2096 // exception path before deoptimization is able to retrieve them.
2097 //
2098 RegisterMap map(this, false);
2099 frame caller_fr = last_frame().sender(&map);
2100 assert(caller_fr.is_compiled_frame(), "what?");
2101 if (caller_fr.is_deoptimized_frame()) {
2102 log_info(exceptions)("deferred async exception at compiled safepoint");
2103 return;
2104 }
2105 }
2106 }
2107
2108 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2109 if (condition == _no_async_condition) {
2110 // Conditions have changed since has_special_runtime_exit_condition()
2111 // was called:
2112 // - if we were here only because of an external suspend request,
2113 // then that was taken care of above (or cancelled) so we are done
2114 // - if we were here because of another async request, then it has
2115 // been cleared between the has_special_runtime_exit_condition()
2116 // and now so again we are done
2117 return;
2118 }
2119
2120 // Check for pending async. exception
2121 if (_pending_async_exception != NULL) {
2122 // Only overwrite an already pending exception, if it is not a threadDeath.
2123 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2124
2125 // We cannot call Exceptions::_throw(...) here because we cannot block
2126 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2127
2128 if (log_is_enabled(Info, exceptions)) {
2129 ResourceMark rm;
2130 outputStream* logstream = Log(exceptions)::info_stream();
2131 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2132 if (has_last_Java_frame()) {
2133 frame f = last_frame();
2134 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2135 }
2136 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2137 }
2138 _pending_async_exception = NULL;
2139 clear_has_async_exception();
2140 }
2141 }
2142
2143 if (check_unsafe_error &&
2144 condition == _async_unsafe_access_error && !has_pending_exception()) {
2145 condition = _no_async_condition; // done
2146 switch (thread_state()) {
2147 case _thread_in_vm: {
2148 JavaThread* THREAD = this;
2149 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2150 }
2151 case _thread_in_native: {
2152 ThreadInVMfromNative tiv(this);
2153 JavaThread* THREAD = this;
2154 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2155 }
2156 case _thread_in_Java: {
2157 ThreadInVMfromJava tiv(this);
2158 JavaThread* THREAD = this;
2159 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2160 }
2161 default:
2162 ShouldNotReachHere();
2163 }
2164 }
2165
2166 assert(condition == _no_async_condition || has_pending_exception() ||
2167 (!check_unsafe_error && condition == _async_unsafe_access_error),
2168 "must have handled the async condition, if no exception");
2169 }
2170
2171 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2172 //
2173 // Check for pending external suspend. Internal suspend requests do
2174 // not use handle_special_runtime_exit_condition().
2175 // If JNIEnv proxies are allowed, don't self-suspend if the target
2176 // thread is not the current thread. In older versions of jdbx, jdbx
2177 // threads could call into the VM with another thread's JNIEnv so we
2178 // can be here operating on behalf of a suspended thread (4432884).
2179 bool do_self_suspend = is_external_suspend_with_lock();
2180 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2181 //
2182 // Because thread is external suspended the safepoint code will count
2183 // thread as at a safepoint. This can be odd because we can be here
2184 // as _thread_in_Java which would normally transition to _thread_blocked
2185 // at a safepoint. We would like to mark the thread as _thread_blocked
2186 // before calling java_suspend_self like all other callers of it but
2187 // we must then observe proper safepoint protocol. (We can't leave
2188 // _thread_blocked with a safepoint in progress). However we can be
2189 // here as _thread_in_native_trans so we can't use a normal transition
2190 // constructor/destructor pair because they assert on that type of
2191 // transition. We could do something like:
2192 //
2193 // JavaThreadState state = thread_state();
2194 // set_thread_state(_thread_in_vm);
2195 // {
2196 // ThreadBlockInVM tbivm(this);
2197 // java_suspend_self()
2198 // }
2199 // set_thread_state(_thread_in_vm_trans);
2200 // if (safepoint) block;
2201 // set_thread_state(state);
2202 //
2203 // but that is pretty messy. Instead we just go with the way the
2204 // code has worked before and note that this is the only path to
2205 // java_suspend_self that doesn't put the thread in _thread_blocked
2206 // mode.
2207
2208 frame_anchor()->make_walkable(this);
2209 java_suspend_self();
2210
2211 // We might be here for reasons in addition to the self-suspend request
2212 // so check for other async requests.
2213 }
2214
2215 if (check_asyncs) {
2216 check_and_handle_async_exceptions();
2217 }
2218 }
2219
2220 void JavaThread::send_thread_stop(oop java_throwable) {
2221 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2222 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2223 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2224
2225 // Do not throw asynchronous exceptions against the compiler thread
2226 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2227 if (!can_call_java()) return;
2228
2229 {
2230 // Actually throw the Throwable against the target Thread - however
2231 // only if there is no thread death exception installed already.
2232 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2233 // If the topmost frame is a runtime stub, then we are calling into
2234 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2235 // must deoptimize the caller before continuing, as the compiled exception handler table
2236 // may not be valid
2237 if (has_last_Java_frame()) {
2238 frame f = last_frame();
2239 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2240 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2241 RegisterMap reg_map(this, UseBiasedLocking);
2242 frame compiled_frame = f.sender(®_map);
2243 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2244 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2245 }
2246 }
2247 }
2248
2249 // Set async. pending exception in thread.
2250 set_pending_async_exception(java_throwable);
2251
2252 if (log_is_enabled(Info, exceptions)) {
2253 ResourceMark rm;
2254 log_info(exceptions)("Pending Async. exception installed of type: %s",
2255 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2256 }
2257 // for AbortVMOnException flag
2258 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2259 }
2260 }
2261
2262
2263 // Interrupt thread so it will wake up from a potential wait()
2264 Thread::interrupt(this);
2265 }
2266
2267 // External suspension mechanism.
2268 //
2269 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2270 // to any VM_locks and it is at a transition
2271 // Self-suspension will happen on the transition out of the vm.
2272 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2273 //
2274 // Guarantees on return:
2275 // + Target thread will not execute any new bytecode (that's why we need to
2276 // force a safepoint)
2277 // + Target thread will not enter any new monitors
2278 //
2279 void JavaThread::java_suspend() {
2280 { MutexLocker mu(Threads_lock);
2281 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2282 return;
2283 }
2284 }
2285
2286 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2287 if (!is_external_suspend()) {
2288 // a racing resume has cancelled us; bail out now
2289 return;
2290 }
2291
2292 // suspend is done
2293 uint32_t debug_bits = 0;
2294 // Warning: is_ext_suspend_completed() may temporarily drop the
2295 // SR_lock to allow the thread to reach a stable thread state if
2296 // it is currently in a transient thread state.
2297 if (is_ext_suspend_completed(false /* !called_by_wait */,
2298 SuspendRetryDelay, &debug_bits)) {
2299 return;
2300 }
2301 }
2302
2303 VM_ForceSafepoint vm_suspend;
2304 VMThread::execute(&vm_suspend);
2305 }
2306
2307 // Part II of external suspension.
2308 // A JavaThread self suspends when it detects a pending external suspend
2309 // request. This is usually on transitions. It is also done in places
2310 // where continuing to the next transition would surprise the caller,
2311 // e.g., monitor entry.
2312 //
2313 // Returns the number of times that the thread self-suspended.
2314 //
2315 // Note: DO NOT call java_suspend_self() when you just want to block current
2316 // thread. java_suspend_self() is the second stage of cooperative
2317 // suspension for external suspend requests and should only be used
2318 // to complete an external suspend request.
2319 //
2320 int JavaThread::java_suspend_self() {
2321 int ret = 0;
2322
2323 // we are in the process of exiting so don't suspend
2324 if (is_exiting()) {
2325 clear_external_suspend();
2326 return ret;
2327 }
2328
2329 assert(_anchor.walkable() ||
2330 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2331 "must have walkable stack");
2332
2333 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2334
2335 assert(!this->is_ext_suspended(),
2336 "a thread trying to self-suspend should not already be suspended");
2337
2338 if (this->is_suspend_equivalent()) {
2339 // If we are self-suspending as a result of the lifting of a
2340 // suspend equivalent condition, then the suspend_equivalent
2341 // flag is not cleared until we set the ext_suspended flag so
2342 // that wait_for_ext_suspend_completion() returns consistent
2343 // results.
2344 this->clear_suspend_equivalent();
2345 }
2346
2347 // A racing resume may have cancelled us before we grabbed SR_lock
2348 // above. Or another external suspend request could be waiting for us
2349 // by the time we return from SR_lock()->wait(). The thread
2350 // that requested the suspension may already be trying to walk our
2351 // stack and if we return now, we can change the stack out from under
2352 // it. This would be a "bad thing (TM)" and cause the stack walker
2353 // to crash. We stay self-suspended until there are no more pending
2354 // external suspend requests.
2355 while (is_external_suspend()) {
2356 ret++;
2357 this->set_ext_suspended();
2358
2359 // _ext_suspended flag is cleared by java_resume()
2360 while (is_ext_suspended()) {
2361 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2362 }
2363 }
2364
2365 return ret;
2366 }
2367
2368 #ifdef ASSERT
2369 // verify the JavaThread has not yet been published in the Threads::list, and
2370 // hence doesn't need protection from concurrent access at this stage
2371 void JavaThread::verify_not_published() {
2372 if (!Threads_lock->owned_by_self()) {
2373 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2374 assert(!Threads::includes(this),
2375 "java thread shouldn't have been published yet!");
2376 } else {
2377 assert(!Threads::includes(this),
2378 "java thread shouldn't have been published yet!");
2379 }
2380 }
2381 #endif
2382
2383 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2384 // progress or when _suspend_flags is non-zero.
2385 // Current thread needs to self-suspend if there is a suspend request and/or
2386 // block if a safepoint is in progress.
2387 // Async exception ISN'T checked.
2388 // Note only the ThreadInVMfromNative transition can call this function
2389 // directly and when thread state is _thread_in_native_trans
2390 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2391 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2392
2393 JavaThread *curJT = JavaThread::current();
2394 bool do_self_suspend = thread->is_external_suspend();
2395
2396 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2397
2398 // If JNIEnv proxies are allowed, don't self-suspend if the target
2399 // thread is not the current thread. In older versions of jdbx, jdbx
2400 // threads could call into the VM with another thread's JNIEnv so we
2401 // can be here operating on behalf of a suspended thread (4432884).
2402 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2403 JavaThreadState state = thread->thread_state();
2404
2405 // We mark this thread_blocked state as a suspend-equivalent so
2406 // that a caller to is_ext_suspend_completed() won't be confused.
2407 // The suspend-equivalent state is cleared by java_suspend_self().
2408 thread->set_suspend_equivalent();
2409
2410 // If the safepoint code sees the _thread_in_native_trans state, it will
2411 // wait until the thread changes to other thread state. There is no
2412 // guarantee on how soon we can obtain the SR_lock and complete the
2413 // self-suspend request. It would be a bad idea to let safepoint wait for
2414 // too long. Temporarily change the state to _thread_blocked to
2415 // let the VM thread know that this thread is ready for GC. The problem
2416 // of changing thread state is that safepoint could happen just after
2417 // java_suspend_self() returns after being resumed, and VM thread will
2418 // see the _thread_blocked state. We must check for safepoint
2419 // after restoring the state and make sure we won't leave while a safepoint
2420 // is in progress.
2421 thread->set_thread_state(_thread_blocked);
2422 thread->java_suspend_self();
2423 thread->set_thread_state(state);
2424 // Make sure new state is seen by VM thread
2425 if (os::is_MP()) {
2426 if (UseMembar) {
2427 // Force a fence between the write above and read below
2428 OrderAccess::fence();
2429 } else {
2430 // Must use this rather than serialization page in particular on Windows
2431 InterfaceSupport::serialize_memory(thread);
2432 }
2433 }
2434 }
2435
2436 if (SafepointSynchronize::do_call_back()) {
2437 // If we are safepointing, then block the caller which may not be
2438 // the same as the target thread (see above).
2439 SafepointSynchronize::block(curJT);
2440 }
2441
2442 if (thread->is_deopt_suspend()) {
2443 thread->clear_deopt_suspend();
2444 RegisterMap map(thread, false);
2445 frame f = thread->last_frame();
2446 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2447 f = f.sender(&map);
2448 }
2449 if (f.id() == thread->must_deopt_id()) {
2450 thread->clear_must_deopt_id();
2451 f.deoptimize(thread);
2452 } else {
2453 fatal("missed deoptimization!");
2454 }
2455 }
2456 }
2457
2458 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2459 // progress or when _suspend_flags is non-zero.
2460 // Current thread needs to self-suspend if there is a suspend request and/or
2461 // block if a safepoint is in progress.
2462 // Also check for pending async exception (not including unsafe access error).
2463 // Note only the native==>VM/Java barriers can call this function and when
2464 // thread state is _thread_in_native_trans.
2465 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2466 check_safepoint_and_suspend_for_native_trans(thread);
2467
2468 if (thread->has_async_exception()) {
2469 // We are in _thread_in_native_trans state, don't handle unsafe
2470 // access error since that may block.
2471 thread->check_and_handle_async_exceptions(false);
2472 }
2473 }
2474
2475 // This is a variant of the normal
2476 // check_special_condition_for_native_trans with slightly different
2477 // semantics for use by critical native wrappers. It does all the
2478 // normal checks but also performs the transition back into
2479 // thread_in_Java state. This is required so that critical natives
2480 // can potentially block and perform a GC if they are the last thread
2481 // exiting the GCLocker.
2482 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2483 check_special_condition_for_native_trans(thread);
2484
2485 // Finish the transition
2486 thread->set_thread_state(_thread_in_Java);
2487
2488 if (thread->do_critical_native_unlock()) {
2489 ThreadInVMfromJavaNoAsyncException tiv(thread);
2490 GCLocker::unlock_critical(thread);
2491 thread->clear_critical_native_unlock();
2492 }
2493 }
2494
2495 // We need to guarantee the Threads_lock here, since resumes are not
2496 // allowed during safepoint synchronization
2497 // Can only resume from an external suspension
2498 void JavaThread::java_resume() {
2499 assert_locked_or_safepoint(Threads_lock);
2500
2501 // Sanity check: thread is gone, has started exiting or the thread
2502 // was not externally suspended.
2503 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2504 return;
2505 }
2506
2507 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2508
2509 clear_external_suspend();
2510
2511 if (is_ext_suspended()) {
2512 clear_ext_suspended();
2513 SR_lock()->notify_all();
2514 }
2515 }
2516
2517 size_t JavaThread::_stack_red_zone_size = 0;
2518 size_t JavaThread::_stack_yellow_zone_size = 0;
2519 size_t JavaThread::_stack_reserved_zone_size = 0;
2520 size_t JavaThread::_stack_shadow_zone_size = 0;
2521
2522 void JavaThread::create_stack_guard_pages() {
2523 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2524 address low_addr = stack_end();
2525 size_t len = stack_guard_zone_size();
2526
2527 int must_commit = os::must_commit_stack_guard_pages();
2528 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2529
2530 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2531 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2532 return;
2533 }
2534
2535 if (os::guard_memory((char *) low_addr, len)) {
2536 _stack_guard_state = stack_guard_enabled;
2537 } else {
2538 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2539 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2540 if (os::uncommit_memory((char *) low_addr, len)) {
2541 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2542 }
2543 return;
2544 }
2545
2546 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2547 PTR_FORMAT "-" PTR_FORMAT ".",
2548 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2549 }
2550
2551 void JavaThread::remove_stack_guard_pages() {
2552 assert(Thread::current() == this, "from different thread");
2553 if (_stack_guard_state == stack_guard_unused) return;
2554 address low_addr = stack_end();
2555 size_t len = stack_guard_zone_size();
2556
2557 if (os::must_commit_stack_guard_pages()) {
2558 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2559 _stack_guard_state = stack_guard_unused;
2560 } else {
2561 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2562 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2563 return;
2564 }
2565 } else {
2566 if (_stack_guard_state == stack_guard_unused) return;
2567 if (os::unguard_memory((char *) low_addr, len)) {
2568 _stack_guard_state = stack_guard_unused;
2569 } else {
2570 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2571 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2572 return;
2573 }
2574 }
2575
2576 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2577 PTR_FORMAT "-" PTR_FORMAT ".",
2578 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2579 }
2580
2581 void JavaThread::enable_stack_reserved_zone() {
2582 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2583 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2584
2585 // The base notation is from the stack's point of view, growing downward.
2586 // We need to adjust it to work correctly with guard_memory()
2587 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2588
2589 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2590 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2591
2592 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2593 _stack_guard_state = stack_guard_enabled;
2594 } else {
2595 warning("Attempt to guard stack reserved zone failed.");
2596 }
2597 enable_register_stack_guard();
2598 }
2599
2600 void JavaThread::disable_stack_reserved_zone() {
2601 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2602 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2603
2604 // Simply return if called for a thread that does not use guard pages.
2605 if (_stack_guard_state == stack_guard_unused) return;
2606
2607 // The base notation is from the stack's point of view, growing downward.
2608 // We need to adjust it to work correctly with guard_memory()
2609 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2610
2611 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2612 _stack_guard_state = stack_guard_reserved_disabled;
2613 } else {
2614 warning("Attempt to unguard stack reserved zone failed.");
2615 }
2616 disable_register_stack_guard();
2617 }
2618
2619 void JavaThread::enable_stack_yellow_reserved_zone() {
2620 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2621 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2622
2623 // The base notation is from the stacks point of view, growing downward.
2624 // We need to adjust it to work correctly with guard_memory()
2625 address base = stack_red_zone_base();
2626
2627 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2628 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2629
2630 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2631 _stack_guard_state = stack_guard_enabled;
2632 } else {
2633 warning("Attempt to guard stack yellow zone failed.");
2634 }
2635 enable_register_stack_guard();
2636 }
2637
2638 void JavaThread::disable_stack_yellow_reserved_zone() {
2639 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2640 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2641
2642 // Simply return if called for a thread that does not use guard pages.
2643 if (_stack_guard_state == stack_guard_unused) return;
2644
2645 // The base notation is from the stacks point of view, growing downward.
2646 // We need to adjust it to work correctly with guard_memory()
2647 address base = stack_red_zone_base();
2648
2649 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2650 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2651 } else {
2652 warning("Attempt to unguard stack yellow zone failed.");
2653 }
2654 disable_register_stack_guard();
2655 }
2656
2657 void JavaThread::enable_stack_red_zone() {
2658 // The base notation is from the stacks point of view, growing downward.
2659 // We need to adjust it to work correctly with guard_memory()
2660 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2661 address base = stack_red_zone_base() - stack_red_zone_size();
2662
2663 guarantee(base < stack_base(), "Error calculating stack red zone");
2664 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2665
2666 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2667 warning("Attempt to guard stack red zone failed.");
2668 }
2669 }
2670
2671 void JavaThread::disable_stack_red_zone() {
2672 // The base notation is from the stacks point of view, growing downward.
2673 // We need to adjust it to work correctly with guard_memory()
2674 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2675 address base = stack_red_zone_base() - stack_red_zone_size();
2676 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2677 warning("Attempt to unguard stack red zone failed.");
2678 }
2679 }
2680
2681 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2682 // ignore is there is no stack
2683 if (!has_last_Java_frame()) return;
2684 // traverse the stack frames. Starts from top frame.
2685 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2686 frame* fr = fst.current();
2687 f(fr, fst.register_map());
2688 }
2689 }
2690
2691
2692 #ifndef PRODUCT
2693 // Deoptimization
2694 // Function for testing deoptimization
2695 void JavaThread::deoptimize() {
2696 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2697 StackFrameStream fst(this, UseBiasedLocking);
2698 bool deopt = false; // Dump stack only if a deopt actually happens.
2699 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2700 // Iterate over all frames in the thread and deoptimize
2701 for (; !fst.is_done(); fst.next()) {
2702 if (fst.current()->can_be_deoptimized()) {
2703
2704 if (only_at) {
2705 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2706 // consists of comma or carriage return separated numbers so
2707 // search for the current bci in that string.
2708 address pc = fst.current()->pc();
2709 nmethod* nm = (nmethod*) fst.current()->cb();
2710 ScopeDesc* sd = nm->scope_desc_at(pc);
2711 char buffer[8];
2712 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2713 size_t len = strlen(buffer);
2714 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2715 while (found != NULL) {
2716 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2717 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2718 // Check that the bci found is bracketed by terminators.
2719 break;
2720 }
2721 found = strstr(found + 1, buffer);
2722 }
2723 if (!found) {
2724 continue;
2725 }
2726 }
2727
2728 if (DebugDeoptimization && !deopt) {
2729 deopt = true; // One-time only print before deopt
2730 tty->print_cr("[BEFORE Deoptimization]");
2731 trace_frames();
2732 trace_stack();
2733 }
2734 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2735 }
2736 }
2737
2738 if (DebugDeoptimization && deopt) {
2739 tty->print_cr("[AFTER Deoptimization]");
2740 trace_frames();
2741 }
2742 }
2743
2744
2745 // Make zombies
2746 void JavaThread::make_zombies() {
2747 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2748 if (fst.current()->can_be_deoptimized()) {
2749 // it is a Java nmethod
2750 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2751 nm->make_not_entrant();
2752 }
2753 }
2754 }
2755 #endif // PRODUCT
2756
2757
2758 void JavaThread::deoptimized_wrt_marked_nmethods() {
2759 if (!has_last_Java_frame()) return;
2760 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2761 StackFrameStream fst(this, UseBiasedLocking);
2762 for (; !fst.is_done(); fst.next()) {
2763 if (fst.current()->should_be_deoptimized()) {
2764 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2765 }
2766 }
2767 }
2768
2769
2770 // If the caller is a NamedThread, then remember, in the current scope,
2771 // the given JavaThread in its _processed_thread field.
2772 class RememberProcessedThread: public StackObj {
2773 NamedThread* _cur_thr;
2774 public:
2775 RememberProcessedThread(JavaThread* jthr) {
2776 Thread* thread = Thread::current();
2777 if (thread->is_Named_thread()) {
2778 _cur_thr = (NamedThread *)thread;
2779 _cur_thr->set_processed_thread(jthr);
2780 } else {
2781 _cur_thr = NULL;
2782 }
2783 }
2784
2785 ~RememberProcessedThread() {
2786 if (_cur_thr) {
2787 _cur_thr->set_processed_thread(NULL);
2788 }
2789 }
2790 };
2791
2792 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2793 // Verify that the deferred card marks have been flushed.
2794 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2795
2796 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2797 // since there may be more than one thread using each ThreadProfiler.
2798
2799 // Traverse the GCHandles
2800 Thread::oops_do(f, cf);
2801
2802 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2803
2804 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2805 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2806
2807 if (has_last_Java_frame()) {
2808 // Record JavaThread to GC thread
2809 RememberProcessedThread rpt(this);
2810
2811 // Traverse the privileged stack
2812 if (_privileged_stack_top != NULL) {
2813 _privileged_stack_top->oops_do(f);
2814 }
2815
2816 // traverse the registered growable array
2817 if (_array_for_gc != NULL) {
2818 for (int index = 0; index < _array_for_gc->length(); index++) {
2819 f->do_oop(_array_for_gc->adr_at(index));
2820 }
2821 }
2822
2823 // Traverse the monitor chunks
2824 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2825 chunk->oops_do(f);
2826 }
2827
2828 // Traverse the execution stack
2829 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2830 fst.current()->oops_do(f, cf, fst.register_map());
2831 }
2832 }
2833
2834 // callee_target is never live across a gc point so NULL it here should
2835 // it still contain a methdOop.
2836
2837 set_callee_target(NULL);
2838
2839 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2840 // If we have deferred set_locals there might be oops waiting to be
2841 // written
2842 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2843 if (list != NULL) {
2844 for (int i = 0; i < list->length(); i++) {
2845 list->at(i)->oops_do(f);
2846 }
2847 }
2848
2849 // Traverse instance variables at the end since the GC may be moving things
2850 // around using this function
2851 f->do_oop((oop*) &_threadObj);
2852 f->do_oop((oop*) &_vm_result);
2853 f->do_oop((oop*) &_exception_oop);
2854 f->do_oop((oop*) &_pending_async_exception);
2855
2856 if (jvmti_thread_state() != NULL) {
2857 jvmti_thread_state()->oops_do(f);
2858 }
2859 }
2860
2861 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2862 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2863 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2864
2865 if (has_last_Java_frame()) {
2866 // Traverse the execution stack
2867 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2868 fst.current()->nmethods_do(cf);
2869 }
2870 }
2871 }
2872
2873 void JavaThread::metadata_do(void f(Metadata*)) {
2874 if (has_last_Java_frame()) {
2875 // Traverse the execution stack to call f() on the methods in the stack
2876 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2877 fst.current()->metadata_do(f);
2878 }
2879 } else if (is_Compiler_thread()) {
2880 // need to walk ciMetadata in current compile tasks to keep alive.
2881 CompilerThread* ct = (CompilerThread*)this;
2882 if (ct->env() != NULL) {
2883 ct->env()->metadata_do(f);
2884 }
2885 if (ct->task() != NULL) {
2886 ct->task()->metadata_do(f);
2887 }
2888 }
2889 }
2890
2891 // Printing
2892 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2893 switch (_thread_state) {
2894 case _thread_uninitialized: return "_thread_uninitialized";
2895 case _thread_new: return "_thread_new";
2896 case _thread_new_trans: return "_thread_new_trans";
2897 case _thread_in_native: return "_thread_in_native";
2898 case _thread_in_native_trans: return "_thread_in_native_trans";
2899 case _thread_in_vm: return "_thread_in_vm";
2900 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2901 case _thread_in_Java: return "_thread_in_Java";
2902 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2903 case _thread_blocked: return "_thread_blocked";
2904 case _thread_blocked_trans: return "_thread_blocked_trans";
2905 default: return "unknown thread state";
2906 }
2907 }
2908
2909 #ifndef PRODUCT
2910 void JavaThread::print_thread_state_on(outputStream *st) const {
2911 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2912 };
2913 void JavaThread::print_thread_state() const {
2914 print_thread_state_on(tty);
2915 }
2916 #endif // PRODUCT
2917
2918 // Called by Threads::print() for VM_PrintThreads operation
2919 void JavaThread::print_on(outputStream *st) const {
2920 st->print_raw("\"");
2921 st->print_raw(get_thread_name());
2922 st->print_raw("\" ");
2923 oop thread_oop = threadObj();
2924 if (thread_oop != NULL) {
2925 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2926 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2927 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2928 }
2929 Thread::print_on(st);
2930 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2931 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2932 if (thread_oop != NULL) {
2933 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2934 }
2935 #ifndef PRODUCT
2936 print_thread_state_on(st);
2937 _safepoint_state->print_on(st);
2938 #endif // PRODUCT
2939 if (is_Compiler_thread()) {
2940 CompilerThread* ct = (CompilerThread*)this;
2941 if (ct->task() != NULL) {
2942 st->print(" Compiling: ");
2943 ct->task()->print(st, NULL, true, false);
2944 } else {
2945 st->print(" No compile task");
2946 }
2947 st->cr();
2948 }
2949 }
2950
2951 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2952 st->print("%s", get_thread_name_string(buf, buflen));
2953 }
2954
2955 // Called by fatal error handler. The difference between this and
2956 // JavaThread::print() is that we can't grab lock or allocate memory.
2957 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2958 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2959 oop thread_obj = threadObj();
2960 if (thread_obj != NULL) {
2961 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2962 }
2963 st->print(" [");
2964 st->print("%s", _get_thread_state_name(_thread_state));
2965 if (osthread()) {
2966 st->print(", id=%d", osthread()->thread_id());
2967 }
2968 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2969 p2i(stack_end()), p2i(stack_base()));
2970 st->print("]");
2971 return;
2972 }
2973
2974 // Verification
2975
2976 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2977
2978 void JavaThread::verify() {
2979 // Verify oops in the thread.
2980 oops_do(&VerifyOopClosure::verify_oop, NULL);
2981
2982 // Verify the stack frames.
2983 frames_do(frame_verify);
2984 }
2985
2986 // CR 6300358 (sub-CR 2137150)
2987 // Most callers of this method assume that it can't return NULL but a
2988 // thread may not have a name whilst it is in the process of attaching to
2989 // the VM - see CR 6412693, and there are places where a JavaThread can be
2990 // seen prior to having it's threadObj set (eg JNI attaching threads and
2991 // if vm exit occurs during initialization). These cases can all be accounted
2992 // for such that this method never returns NULL.
2993 const char* JavaThread::get_thread_name() const {
2994 #ifdef ASSERT
2995 // early safepoints can hit while current thread does not yet have TLS
2996 if (!SafepointSynchronize::is_at_safepoint()) {
2997 Thread *cur = Thread::current();
2998 if (!(cur->is_Java_thread() && cur == this)) {
2999 // Current JavaThreads are allowed to get their own name without
3000 // the Threads_lock.
3001 assert_locked_or_safepoint(Threads_lock);
3002 }
3003 }
3004 #endif // ASSERT
3005 return get_thread_name_string();
3006 }
3007
3008 // Returns a non-NULL representation of this thread's name, or a suitable
3009 // descriptive string if there is no set name
3010 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3011 const char* name_str;
3012 oop thread_obj = threadObj();
3013 if (thread_obj != NULL) {
3014 oop name = java_lang_Thread::name(thread_obj);
3015 if (name != NULL) {
3016 if (buf == NULL) {
3017 name_str = java_lang_String::as_utf8_string(name);
3018 } else {
3019 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3020 }
3021 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3022 name_str = "<no-name - thread is attaching>";
3023 } else {
3024 name_str = Thread::name();
3025 }
3026 } else {
3027 name_str = Thread::name();
3028 }
3029 assert(name_str != NULL, "unexpected NULL thread name");
3030 return name_str;
3031 }
3032
3033
3034 const char* JavaThread::get_threadgroup_name() const {
3035 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3036 oop thread_obj = threadObj();
3037 if (thread_obj != NULL) {
3038 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3039 if (thread_group != NULL) {
3040 // ThreadGroup.name can be null
3041 return java_lang_ThreadGroup::name(thread_group);
3042 }
3043 }
3044 return NULL;
3045 }
3046
3047 const char* JavaThread::get_parent_name() const {
3048 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3049 oop thread_obj = threadObj();
3050 if (thread_obj != NULL) {
3051 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3052 if (thread_group != NULL) {
3053 oop parent = java_lang_ThreadGroup::parent(thread_group);
3054 if (parent != NULL) {
3055 // ThreadGroup.name can be null
3056 return java_lang_ThreadGroup::name(parent);
3057 }
3058 }
3059 }
3060 return NULL;
3061 }
3062
3063 ThreadPriority JavaThread::java_priority() const {
3064 oop thr_oop = threadObj();
3065 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3066 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3067 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3068 return priority;
3069 }
3070
3071 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3072
3073 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3074 // Link Java Thread object <-> C++ Thread
3075
3076 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3077 // and put it into a new Handle. The Handle "thread_oop" can then
3078 // be used to pass the C++ thread object to other methods.
3079
3080 // Set the Java level thread object (jthread) field of the
3081 // new thread (a JavaThread *) to C++ thread object using the
3082 // "thread_oop" handle.
3083
3084 // Set the thread field (a JavaThread *) of the
3085 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3086
3087 Handle thread_oop(Thread::current(),
3088 JNIHandles::resolve_non_null(jni_thread));
3089 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3090 "must be initialized");
3091 set_threadObj(thread_oop());
3092 java_lang_Thread::set_thread(thread_oop(), this);
3093
3094 if (prio == NoPriority) {
3095 prio = java_lang_Thread::priority(thread_oop());
3096 assert(prio != NoPriority, "A valid priority should be present");
3097 }
3098
3099 // Push the Java priority down to the native thread; needs Threads_lock
3100 Thread::set_priority(this, prio);
3101
3102 prepare_ext();
3103
3104 // Add the new thread to the Threads list and set it in motion.
3105 // We must have threads lock in order to call Threads::add.
3106 // It is crucial that we do not block before the thread is
3107 // added to the Threads list for if a GC happens, then the java_thread oop
3108 // will not be visited by GC.
3109 Threads::add(this);
3110 }
3111
3112 oop JavaThread::current_park_blocker() {
3113 // Support for JSR-166 locks
3114 oop thread_oop = threadObj();
3115 if (thread_oop != NULL &&
3116 JDK_Version::current().supports_thread_park_blocker()) {
3117 return java_lang_Thread::park_blocker(thread_oop);
3118 }
3119 return NULL;
3120 }
3121
3122
3123 void JavaThread::print_stack_on(outputStream* st) {
3124 if (!has_last_Java_frame()) return;
3125 ResourceMark rm;
3126 HandleMark hm;
3127
3128 RegisterMap reg_map(this);
3129 vframe* start_vf = last_java_vframe(®_map);
3130 int count = 0;
3131 for (vframe* f = start_vf; f; f = f->sender()) {
3132 if (f->is_java_frame()) {
3133 javaVFrame* jvf = javaVFrame::cast(f);
3134 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3135
3136 // Print out lock information
3137 if (JavaMonitorsInStackTrace) {
3138 jvf->print_lock_info_on(st, count);
3139 }
3140 } else {
3141 // Ignore non-Java frames
3142 }
3143
3144 // Bail-out case for too deep stacks
3145 count++;
3146 if (MaxJavaStackTraceDepth == count) return;
3147 }
3148 }
3149
3150
3151 // JVMTI PopFrame support
3152 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3153 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3154 if (in_bytes(size_in_bytes) != 0) {
3155 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3156 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3157 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3158 }
3159 }
3160
3161 void* JavaThread::popframe_preserved_args() {
3162 return _popframe_preserved_args;
3163 }
3164
3165 ByteSize JavaThread::popframe_preserved_args_size() {
3166 return in_ByteSize(_popframe_preserved_args_size);
3167 }
3168
3169 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3170 int sz = in_bytes(popframe_preserved_args_size());
3171 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3172 return in_WordSize(sz / wordSize);
3173 }
3174
3175 void JavaThread::popframe_free_preserved_args() {
3176 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3177 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3178 _popframe_preserved_args = NULL;
3179 _popframe_preserved_args_size = 0;
3180 }
3181
3182 #ifndef PRODUCT
3183
3184 void JavaThread::trace_frames() {
3185 tty->print_cr("[Describe stack]");
3186 int frame_no = 1;
3187 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3188 tty->print(" %d. ", frame_no++);
3189 fst.current()->print_value_on(tty, this);
3190 tty->cr();
3191 }
3192 }
3193
3194 class PrintAndVerifyOopClosure: public OopClosure {
3195 protected:
3196 template <class T> inline void do_oop_work(T* p) {
3197 oop obj = oopDesc::load_decode_heap_oop(p);
3198 if (obj == NULL) return;
3199 tty->print(INTPTR_FORMAT ": ", p2i(p));
3200 if (obj->is_oop_or_null()) {
3201 if (obj->is_objArray()) {
3202 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3203 } else {
3204 obj->print();
3205 }
3206 } else {
3207 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3208 }
3209 tty->cr();
3210 }
3211 public:
3212 virtual void do_oop(oop* p) { do_oop_work(p); }
3213 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3214 };
3215
3216
3217 static void oops_print(frame* f, const RegisterMap *map) {
3218 PrintAndVerifyOopClosure print;
3219 f->print_value();
3220 f->oops_do(&print, NULL, (RegisterMap*)map);
3221 }
3222
3223 // Print our all the locations that contain oops and whether they are
3224 // valid or not. This useful when trying to find the oldest frame
3225 // where an oop has gone bad since the frame walk is from youngest to
3226 // oldest.
3227 void JavaThread::trace_oops() {
3228 tty->print_cr("[Trace oops]");
3229 frames_do(oops_print);
3230 }
3231
3232
3233 #ifdef ASSERT
3234 // Print or validate the layout of stack frames
3235 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3236 ResourceMark rm;
3237 PRESERVE_EXCEPTION_MARK;
3238 FrameValues values;
3239 int frame_no = 0;
3240 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3241 fst.current()->describe(values, ++frame_no);
3242 if (depth == frame_no) break;
3243 }
3244 if (validate_only) {
3245 values.validate();
3246 } else {
3247 tty->print_cr("[Describe stack layout]");
3248 values.print(this);
3249 }
3250 }
3251 #endif
3252
3253 void JavaThread::trace_stack_from(vframe* start_vf) {
3254 ResourceMark rm;
3255 int vframe_no = 1;
3256 for (vframe* f = start_vf; f; f = f->sender()) {
3257 if (f->is_java_frame()) {
3258 javaVFrame::cast(f)->print_activation(vframe_no++);
3259 } else {
3260 f->print();
3261 }
3262 if (vframe_no > StackPrintLimit) {
3263 tty->print_cr("...<more frames>...");
3264 return;
3265 }
3266 }
3267 }
3268
3269
3270 void JavaThread::trace_stack() {
3271 if (!has_last_Java_frame()) return;
3272 ResourceMark rm;
3273 HandleMark hm;
3274 RegisterMap reg_map(this);
3275 trace_stack_from(last_java_vframe(®_map));
3276 }
3277
3278
3279 #endif // PRODUCT
3280
3281
3282 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3283 assert(reg_map != NULL, "a map must be given");
3284 frame f = last_frame();
3285 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3286 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3287 }
3288 return NULL;
3289 }
3290
3291
3292 Klass* JavaThread::security_get_caller_class(int depth) {
3293 vframeStream vfst(this);
3294 vfst.security_get_caller_frame(depth);
3295 if (!vfst.at_end()) {
3296 return vfst.method()->method_holder();
3297 }
3298 return NULL;
3299 }
3300
3301 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3302 assert(thread->is_Compiler_thread(), "must be compiler thread");
3303 CompileBroker::compiler_thread_loop();
3304 }
3305
3306 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3307 NMethodSweeper::sweeper_loop();
3308 }
3309
3310 // Create a CompilerThread
3311 CompilerThread::CompilerThread(CompileQueue* queue,
3312 CompilerCounters* counters)
3313 : JavaThread(&compiler_thread_entry) {
3314 _env = NULL;
3315 _log = NULL;
3316 _task = NULL;
3317 _queue = queue;
3318 _counters = counters;
3319 _buffer_blob = NULL;
3320 _compiler = NULL;
3321
3322 #ifndef PRODUCT
3323 _ideal_graph_printer = NULL;
3324 #endif
3325 }
3326
3327 bool CompilerThread::can_call_java() const {
3328 return _compiler != NULL && _compiler->is_jvmci();
3329 }
3330
3331 // Create sweeper thread
3332 CodeCacheSweeperThread::CodeCacheSweeperThread()
3333 : JavaThread(&sweeper_thread_entry) {
3334 _scanned_compiled_method = NULL;
3335 }
3336
3337 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3338 JavaThread::oops_do(f, cf);
3339 if (_scanned_compiled_method != NULL && cf != NULL) {
3340 // Safepoints can occur when the sweeper is scanning an nmethod so
3341 // process it here to make sure it isn't unloaded in the middle of
3342 // a scan.
3343 cf->do_code_blob(_scanned_compiled_method);
3344 }
3345 }
3346
3347 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3348 JavaThread::nmethods_do(cf);
3349 if (_scanned_compiled_method != NULL && cf != NULL) {
3350 // Safepoints can occur when the sweeper is scanning an nmethod so
3351 // process it here to make sure it isn't unloaded in the middle of
3352 // a scan.
3353 cf->do_code_blob(_scanned_compiled_method);
3354 }
3355 }
3356
3357
3358 // ======= Threads ========
3359
3360 // The Threads class links together all active threads, and provides
3361 // operations over all threads. It is protected by its own Mutex
3362 // lock, which is also used in other contexts to protect thread
3363 // operations from having the thread being operated on from exiting
3364 // and going away unexpectedly (e.g., safepoint synchronization)
3365
3366 JavaThread* Threads::_thread_list = NULL;
3367 int Threads::_number_of_threads = 0;
3368 int Threads::_number_of_non_daemon_threads = 0;
3369 int Threads::_return_code = 0;
3370 int Threads::_thread_claim_parity = 0;
3371 size_t JavaThread::_stack_size_at_create = 0;
3372 #ifdef ASSERT
3373 bool Threads::_vm_complete = false;
3374 #endif
3375
3376 // All JavaThreads
3377 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3378
3379 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3380 void Threads::threads_do(ThreadClosure* tc) {
3381 assert_locked_or_safepoint(Threads_lock);
3382 // ALL_JAVA_THREADS iterates through all JavaThreads
3383 ALL_JAVA_THREADS(p) {
3384 tc->do_thread(p);
3385 }
3386 // Someday we could have a table or list of all non-JavaThreads.
3387 // For now, just manually iterate through them.
3388 tc->do_thread(VMThread::vm_thread());
3389 Universe::heap()->gc_threads_do(tc);
3390 WatcherThread *wt = WatcherThread::watcher_thread();
3391 // Strictly speaking, the following NULL check isn't sufficient to make sure
3392 // the data for WatcherThread is still valid upon being examined. However,
3393 // considering that WatchThread terminates when the VM is on the way to
3394 // exit at safepoint, the chance of the above is extremely small. The right
3395 // way to prevent termination of WatcherThread would be to acquire
3396 // Terminator_lock, but we can't do that without violating the lock rank
3397 // checking in some cases.
3398 if (wt != NULL) {
3399 tc->do_thread(wt);
3400 }
3401
3402 // If CompilerThreads ever become non-JavaThreads, add them here
3403 }
3404
3405 // The system initialization in the library has three phases.
3406 //
3407 // Phase 1: java.lang.System class initialization
3408 // java.lang.System is a primordial class loaded and initialized
3409 // by the VM early during startup. java.lang.System.<clinit>
3410 // only does registerNatives and keeps the rest of the class
3411 // initialization work later until thread initialization completes.
3412 //
3413 // System.initPhase1 initializes the system properties, the static
3414 // fields in, out, and err. Set up java signal handlers, OS-specific
3415 // system settings, and thread group of the main thread.
3416 static void call_initPhase1(TRAPS) {
3417 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3418 instanceKlassHandle klass (THREAD, k);
3419
3420 JavaValue result(T_VOID);
3421 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3422 vmSymbols::void_method_signature(), CHECK);
3423 }
3424
3425 // Phase 2. Module system initialization
3426 // This will initialize the module system. Only java.base classes
3427 // can be loaded until phase 2 completes.
3428 //
3429 // Call System.initPhase2 after the compiler initialization and jsr292
3430 // classes get initialized because module initialization runs a lot of java
3431 // code, that for performance reasons, should be compiled. Also, this will
3432 // enable the startup code to use lambda and other language features in this
3433 // phase and onward.
3434 //
3435 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3436 static void call_initPhase2(TRAPS) {
3437 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3438
3439 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3440 instanceKlassHandle klass (THREAD, k);
3441
3442 JavaValue result(T_VOID);
3443 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3444 vmSymbols::void_method_signature(), CHECK);
3445 universe_post_module_init();
3446 }
3447
3448 // Phase 3. final setup - set security manager, system class loader and TCCL
3449 //
3450 // This will instantiate and set the security manager, set the system class
3451 // loader as well as the thread context class loader. The security manager
3452 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3453 // other modules or the application's classpath.
3454 static void call_initPhase3(TRAPS) {
3455 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3456 instanceKlassHandle klass (THREAD, k);
3457
3458 JavaValue result(T_VOID);
3459 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3460 vmSymbols::void_method_signature(), CHECK);
3461 }
3462
3463 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3464 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3465
3466 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3467 create_vm_init_libraries();
3468 }
3469
3470 initialize_class(vmSymbols::java_lang_String(), CHECK);
3471
3472 // Inject CompactStrings value after the static initializers for String ran.
3473 java_lang_String::set_compact_strings(CompactStrings);
3474
3475 // Initialize java_lang.System (needed before creating the thread)
3476 initialize_class(vmSymbols::java_lang_System(), CHECK);
3477 // The VM creates & returns objects of this class. Make sure it's initialized.
3478 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3479 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3480 Handle thread_group = create_initial_thread_group(CHECK);
3481 Universe::set_main_thread_group(thread_group());
3482 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3483 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3484 main_thread->set_threadObj(thread_object);
3485 // Set thread status to running since main thread has
3486 // been started and running.
3487 java_lang_Thread::set_thread_status(thread_object,
3488 java_lang_Thread::RUNNABLE);
3489
3490 // The VM creates objects of this class.
3491 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3492
3493 // The VM preresolves methods to these classes. Make sure that they get initialized
3494 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3495 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3496
3497 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3498 call_initPhase1(CHECK);
3499
3500 // get the Java runtime name after java.lang.System is initialized
3501 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3502 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3503
3504 // an instance of OutOfMemory exception has been allocated earlier
3505 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3506 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3507 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3508 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3509 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3510 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3511 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3512 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3513 }
3514
3515 void Threads::initialize_jsr292_core_classes(TRAPS) {
3516 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3517
3518 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3519 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3520 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3521 }
3522
3523 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3524 extern void JDK_Version_init();
3525
3526 // Preinitialize version info.
3527 VM_Version::early_initialize();
3528
3529 // Check version
3530 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3531
3532 // Initialize library-based TLS
3533 ThreadLocalStorage::init();
3534
3535 // Initialize the output stream module
3536 ostream_init();
3537
3538 // Process java launcher properties.
3539 Arguments::process_sun_java_launcher_properties(args);
3540
3541 // Initialize the os module
3542 os::init();
3543
3544 // Record VM creation timing statistics
3545 TraceVmCreationTime create_vm_timer;
3546 create_vm_timer.start();
3547
3548 // Initialize system properties.
3549 Arguments::init_system_properties();
3550
3551 // So that JDK version can be used as a discriminator when parsing arguments
3552 JDK_Version_init();
3553
3554 // Update/Initialize System properties after JDK version number is known
3555 Arguments::init_version_specific_system_properties();
3556
3557 // Make sure to initialize log configuration *before* parsing arguments
3558 LogConfiguration::initialize(create_vm_timer.begin_time());
3559
3560 // Parse arguments
3561 jint parse_result = Arguments::parse(args);
3562 if (parse_result != JNI_OK) return parse_result;
3563
3564 os::init_before_ergo();
3565
3566 jint ergo_result = Arguments::apply_ergo();
3567 if (ergo_result != JNI_OK) return ergo_result;
3568
3569 // Final check of all ranges after ergonomics which may change values.
3570 if (!CommandLineFlagRangeList::check_ranges()) {
3571 return JNI_EINVAL;
3572 }
3573
3574 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3575 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3576 if (!constraint_result) {
3577 return JNI_EINVAL;
3578 }
3579
3580 CommandLineFlagWriteableList::mark_startup();
3581
3582 if (PauseAtStartup) {
3583 os::pause();
3584 }
3585
3586 HOTSPOT_VM_INIT_BEGIN();
3587
3588 // Timing (must come after argument parsing)
3589 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3590
3591 // Initialize the os module after parsing the args
3592 jint os_init_2_result = os::init_2();
3593 if (os_init_2_result != JNI_OK) return os_init_2_result;
3594
3595 jint adjust_after_os_result = Arguments::adjust_after_os();
3596 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3597
3598 // Initialize output stream logging
3599 ostream_init_log();
3600
3601 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3602 // Must be before create_vm_init_agents()
3603 if (Arguments::init_libraries_at_startup()) {
3604 convert_vm_init_libraries_to_agents();
3605 }
3606
3607 // Launch -agentlib/-agentpath and converted -Xrun agents
3608 if (Arguments::init_agents_at_startup()) {
3609 create_vm_init_agents();
3610 }
3611
3612 // Initialize Threads state
3613 _thread_list = NULL;
3614 _number_of_threads = 0;
3615 _number_of_non_daemon_threads = 0;
3616
3617 // Initialize global data structures and create system classes in heap
3618 vm_init_globals();
3619
3620 #if INCLUDE_JVMCI
3621 if (JVMCICounterSize > 0) {
3622 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3623 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3624 } else {
3625 JavaThread::_jvmci_old_thread_counters = NULL;
3626 }
3627 #endif // INCLUDE_JVMCI
3628
3629 // Attach the main thread to this os thread
3630 JavaThread* main_thread = new JavaThread();
3631 main_thread->set_thread_state(_thread_in_vm);
3632 main_thread->initialize_thread_current();
3633 // must do this before set_active_handles
3634 main_thread->record_stack_base_and_size();
3635 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3636
3637 if (!main_thread->set_as_starting_thread()) {
3638 vm_shutdown_during_initialization(
3639 "Failed necessary internal allocation. Out of swap space");
3640 delete main_thread;
3641 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3642 return JNI_ENOMEM;
3643 }
3644
3645 // Enable guard page *after* os::create_main_thread(), otherwise it would
3646 // crash Linux VM, see notes in os_linux.cpp.
3647 main_thread->create_stack_guard_pages();
3648
3649 // Initialize Java-Level synchronization subsystem
3650 ObjectMonitor::Initialize();
3651
3652 // Initialize global modules
3653 jint status = init_globals();
3654 if (status != JNI_OK) {
3655 delete main_thread;
3656 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3657 return status;
3658 }
3659
3660 if (TRACE_INITIALIZE() != JNI_OK) {
3661 vm_exit_during_initialization("Failed to initialize tracing backend");
3662 }
3663
3664 // Should be done after the heap is fully created
3665 main_thread->cache_global_variables();
3666
3667 HandleMark hm;
3668
3669 { MutexLocker mu(Threads_lock);
3670 Threads::add(main_thread);
3671 }
3672
3673 // Any JVMTI raw monitors entered in onload will transition into
3674 // real raw monitor. VM is setup enough here for raw monitor enter.
3675 JvmtiExport::transition_pending_onload_raw_monitors();
3676
3677 // Create the VMThread
3678 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3679
3680 VMThread::create();
3681 Thread* vmthread = VMThread::vm_thread();
3682
3683 if (!os::create_thread(vmthread, os::vm_thread)) {
3684 vm_exit_during_initialization("Cannot create VM thread. "
3685 "Out of system resources.");
3686 }
3687
3688 // Wait for the VM thread to become ready, and VMThread::run to initialize
3689 // Monitors can have spurious returns, must always check another state flag
3690 {
3691 MutexLocker ml(Notify_lock);
3692 os::start_thread(vmthread);
3693 while (vmthread->active_handles() == NULL) {
3694 Notify_lock->wait();
3695 }
3696 }
3697 }
3698
3699 assert(Universe::is_fully_initialized(), "not initialized");
3700 if (VerifyDuringStartup) {
3701 // Make sure we're starting with a clean slate.
3702 VM_Verify verify_op;
3703 VMThread::execute(&verify_op);
3704 }
3705
3706 Thread* THREAD = Thread::current();
3707
3708 // At this point, the Universe is initialized, but we have not executed
3709 // any byte code. Now is a good time (the only time) to dump out the
3710 // internal state of the JVM for sharing.
3711 if (DumpSharedSpaces) {
3712 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3713 ShouldNotReachHere();
3714 }
3715
3716 // Always call even when there are not JVMTI environments yet, since environments
3717 // may be attached late and JVMTI must track phases of VM execution
3718 JvmtiExport::enter_early_start_phase();
3719
3720 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3721 JvmtiExport::post_early_vm_start();
3722
3723 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3724
3725 // We need this for ClassDataSharing - the initial vm.info property is set
3726 // with the default value of CDS "sharing" which may be reset through
3727 // command line options.
3728 reset_vm_info_property(CHECK_JNI_ERR);
3729
3730 quicken_jni_functions();
3731
3732 // No more stub generation allowed after that point.
3733 StubCodeDesc::freeze();
3734
3735 // Set flag that basic initialization has completed. Used by exceptions and various
3736 // debug stuff, that does not work until all basic classes have been initialized.
3737 set_init_completed();
3738
3739 LogConfiguration::post_initialize();
3740 Metaspace::post_initialize();
3741
3742 HOTSPOT_VM_INIT_END();
3743
3744 // record VM initialization completion time
3745 #if INCLUDE_MANAGEMENT
3746 Management::record_vm_init_completed();
3747 #endif // INCLUDE_MANAGEMENT
3748
3749 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3750 // set_init_completed has just been called, causing exceptions not to be shortcut
3751 // anymore. We call vm_exit_during_initialization directly instead.
3752
3753 // Initialize reference pending list locker
3754 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3755 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3756
3757 // Signal Dispatcher needs to be started before VMInit event is posted
3758 os::signal_init();
3759
3760 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3761 if (!DisableAttachMechanism) {
3762 AttachListener::vm_start();
3763 if (StartAttachListener || AttachListener::init_at_startup()) {
3764 AttachListener::init();
3765 }
3766 }
3767
3768 // Launch -Xrun agents
3769 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3770 // back-end can launch with -Xdebug -Xrunjdwp.
3771 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3772 create_vm_init_libraries();
3773 }
3774
3775 if (CleanChunkPoolAsync) {
3776 Chunk::start_chunk_pool_cleaner_task();
3777 }
3778
3779 // initialize compiler(s)
3780 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3781 CompileBroker::compilation_init(CHECK_JNI_ERR);
3782 #endif
3783
3784 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3785 // It is done after compilers are initialized, because otherwise compilations of
3786 // signature polymorphic MH intrinsics can be missed
3787 // (see SystemDictionary::find_method_handle_intrinsic).
3788 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3789
3790 // This will initialize the module system. Only java.base classes can be
3791 // loaded until phase 2 completes
3792 call_initPhase2(CHECK_JNI_ERR);
3793
3794 // Always call even when there are not JVMTI environments yet, since environments
3795 // may be attached late and JVMTI must track phases of VM execution
3796 JvmtiExport::enter_start_phase();
3797
3798 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3799 JvmtiExport::post_vm_start();
3800
3801 // Final system initialization including security manager and system class loader
3802 call_initPhase3(CHECK_JNI_ERR);
3803
3804 // cache the system class loader
3805 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3806
3807 #if INCLUDE_JVMCI
3808 if (EnableJVMCI && UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation)) {
3809 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3810 // compilations via JVMCI will not actually block until JVMCI is initialized.
3811 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3812 }
3813 #endif
3814
3815 // Always call even when there are not JVMTI environments yet, since environments
3816 // may be attached late and JVMTI must track phases of VM execution
3817 JvmtiExport::enter_live_phase();
3818
3819 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3820 JvmtiExport::post_vm_initialized();
3821
3822 if (TRACE_START() != JNI_OK) {
3823 vm_exit_during_initialization("Failed to start tracing backend.");
3824 }
3825
3826 #if INCLUDE_MANAGEMENT
3827 Management::initialize(THREAD);
3828
3829 if (HAS_PENDING_EXCEPTION) {
3830 // management agent fails to start possibly due to
3831 // configuration problem and is responsible for printing
3832 // stack trace if appropriate. Simply exit VM.
3833 vm_exit(1);
3834 }
3835 #endif // INCLUDE_MANAGEMENT
3836
3837 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3838 if (MemProfiling) MemProfiler::engage();
3839 StatSampler::engage();
3840 if (CheckJNICalls) JniPeriodicChecker::engage();
3841
3842 BiasedLocking::init();
3843
3844 #if INCLUDE_RTM_OPT
3845 RTMLockingCounters::init();
3846 #endif
3847
3848 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3849 call_postVMInitHook(THREAD);
3850 // The Java side of PostVMInitHook.run must deal with all
3851 // exceptions and provide means of diagnosis.
3852 if (HAS_PENDING_EXCEPTION) {
3853 CLEAR_PENDING_EXCEPTION;
3854 }
3855 }
3856
3857 {
3858 MutexLocker ml(PeriodicTask_lock);
3859 // Make sure the WatcherThread can be started by WatcherThread::start()
3860 // or by dynamic enrollment.
3861 WatcherThread::make_startable();
3862 // Start up the WatcherThread if there are any periodic tasks
3863 // NOTE: All PeriodicTasks should be registered by now. If they
3864 // aren't, late joiners might appear to start slowly (we might
3865 // take a while to process their first tick).
3866 if (PeriodicTask::num_tasks() > 0) {
3867 WatcherThread::start();
3868 }
3869 }
3870
3871 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3872
3873 create_vm_timer.end();
3874 #ifdef ASSERT
3875 _vm_complete = true;
3876 #endif
3877 return JNI_OK;
3878 }
3879
3880 // type for the Agent_OnLoad and JVM_OnLoad entry points
3881 extern "C" {
3882 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3883 }
3884 // Find a command line agent library and return its entry point for
3885 // -agentlib: -agentpath: -Xrun
3886 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3887 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3888 const char *on_load_symbols[],
3889 size_t num_symbol_entries) {
3890 OnLoadEntry_t on_load_entry = NULL;
3891 void *library = NULL;
3892
3893 if (!agent->valid()) {
3894 char buffer[JVM_MAXPATHLEN];
3895 char ebuf[1024] = "";
3896 const char *name = agent->name();
3897 const char *msg = "Could not find agent library ";
3898
3899 // First check to see if agent is statically linked into executable
3900 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3901 library = agent->os_lib();
3902 } else if (agent->is_absolute_path()) {
3903 library = os::dll_load(name, ebuf, sizeof ebuf);
3904 if (library == NULL) {
3905 const char *sub_msg = " in absolute path, with error: ";
3906 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3907 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3908 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3909 // If we can't find the agent, exit.
3910 vm_exit_during_initialization(buf, NULL);
3911 FREE_C_HEAP_ARRAY(char, buf);
3912 }
3913 } else {
3914 // Try to load the agent from the standard dll directory
3915 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3916 name)) {
3917 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3918 }
3919 if (library == NULL) { // Try the local directory
3920 char ns[1] = {0};
3921 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3922 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3923 }
3924 if (library == NULL) {
3925 const char *sub_msg = " on the library path, with error: ";
3926 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3927 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3928 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3929 // If we can't find the agent, exit.
3930 vm_exit_during_initialization(buf, NULL);
3931 FREE_C_HEAP_ARRAY(char, buf);
3932 }
3933 }
3934 }
3935 agent->set_os_lib(library);
3936 agent->set_valid();
3937 }
3938
3939 // Find the OnLoad function.
3940 on_load_entry =
3941 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3942 false,
3943 on_load_symbols,
3944 num_symbol_entries));
3945 return on_load_entry;
3946 }
3947
3948 // Find the JVM_OnLoad entry point
3949 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3950 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3951 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3952 }
3953
3954 // Find the Agent_OnLoad entry point
3955 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3956 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3957 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3958 }
3959
3960 // For backwards compatibility with -Xrun
3961 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3962 // treated like -agentpath:
3963 // Must be called before agent libraries are created
3964 void Threads::convert_vm_init_libraries_to_agents() {
3965 AgentLibrary* agent;
3966 AgentLibrary* next;
3967
3968 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3969 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3970 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3971
3972 // If there is an JVM_OnLoad function it will get called later,
3973 // otherwise see if there is an Agent_OnLoad
3974 if (on_load_entry == NULL) {
3975 on_load_entry = lookup_agent_on_load(agent);
3976 if (on_load_entry != NULL) {
3977 // switch it to the agent list -- so that Agent_OnLoad will be called,
3978 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3979 Arguments::convert_library_to_agent(agent);
3980 } else {
3981 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3982 }
3983 }
3984 }
3985 }
3986
3987 // Create agents for -agentlib: -agentpath: and converted -Xrun
3988 // Invokes Agent_OnLoad
3989 // Called very early -- before JavaThreads exist
3990 void Threads::create_vm_init_agents() {
3991 extern struct JavaVM_ main_vm;
3992 AgentLibrary* agent;
3993
3994 JvmtiExport::enter_onload_phase();
3995
3996 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3997 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3998
3999 if (on_load_entry != NULL) {
4000 // Invoke the Agent_OnLoad function
4001 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4002 if (err != JNI_OK) {
4003 vm_exit_during_initialization("agent library failed to init", agent->name());
4004 }
4005 } else {
4006 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4007 }
4008 }
4009 JvmtiExport::enter_primordial_phase();
4010 }
4011
4012 extern "C" {
4013 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4014 }
4015
4016 void Threads::shutdown_vm_agents() {
4017 // Send any Agent_OnUnload notifications
4018 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4019 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4020 extern struct JavaVM_ main_vm;
4021 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4022
4023 // Find the Agent_OnUnload function.
4024 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4025 os::find_agent_function(agent,
4026 false,
4027 on_unload_symbols,
4028 num_symbol_entries));
4029
4030 // Invoke the Agent_OnUnload function
4031 if (unload_entry != NULL) {
4032 JavaThread* thread = JavaThread::current();
4033 ThreadToNativeFromVM ttn(thread);
4034 HandleMark hm(thread);
4035 (*unload_entry)(&main_vm);
4036 }
4037 }
4038 }
4039
4040 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4041 // Invokes JVM_OnLoad
4042 void Threads::create_vm_init_libraries() {
4043 extern struct JavaVM_ main_vm;
4044 AgentLibrary* agent;
4045
4046 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4047 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4048
4049 if (on_load_entry != NULL) {
4050 // Invoke the JVM_OnLoad function
4051 JavaThread* thread = JavaThread::current();
4052 ThreadToNativeFromVM ttn(thread);
4053 HandleMark hm(thread);
4054 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4055 if (err != JNI_OK) {
4056 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4057 }
4058 } else {
4059 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4060 }
4061 }
4062 }
4063
4064 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4065 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4066
4067 JavaThread* java_thread = NULL;
4068 // Sequential search for now. Need to do better optimization later.
4069 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4070 oop tobj = thread->threadObj();
4071 if (!thread->is_exiting() &&
4072 tobj != NULL &&
4073 java_tid == java_lang_Thread::thread_id(tobj)) {
4074 java_thread = thread;
4075 break;
4076 }
4077 }
4078 return java_thread;
4079 }
4080
4081
4082 // Last thread running calls java.lang.Shutdown.shutdown()
4083 void JavaThread::invoke_shutdown_hooks() {
4084 HandleMark hm(this);
4085
4086 // We could get here with a pending exception, if so clear it now.
4087 if (this->has_pending_exception()) {
4088 this->clear_pending_exception();
4089 }
4090
4091 EXCEPTION_MARK;
4092 Klass* k =
4093 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4094 THREAD);
4095 if (k != NULL) {
4096 // SystemDictionary::resolve_or_null will return null if there was
4097 // an exception. If we cannot load the Shutdown class, just don't
4098 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4099 // and finalizers (if runFinalizersOnExit is set) won't be run.
4100 // Note that if a shutdown hook was registered or runFinalizersOnExit
4101 // was called, the Shutdown class would have already been loaded
4102 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4103 instanceKlassHandle shutdown_klass (THREAD, k);
4104 JavaValue result(T_VOID);
4105 JavaCalls::call_static(&result,
4106 shutdown_klass,
4107 vmSymbols::shutdown_method_name(),
4108 vmSymbols::void_method_signature(),
4109 THREAD);
4110 }
4111 CLEAR_PENDING_EXCEPTION;
4112 }
4113
4114 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4115 // the program falls off the end of main(). Another VM exit path is through
4116 // vm_exit() when the program calls System.exit() to return a value or when
4117 // there is a serious error in VM. The two shutdown paths are not exactly
4118 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4119 // and VM_Exit op at VM level.
4120 //
4121 // Shutdown sequence:
4122 // + Shutdown native memory tracking if it is on
4123 // + Wait until we are the last non-daemon thread to execute
4124 // <-- every thing is still working at this moment -->
4125 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4126 // shutdown hooks, run finalizers if finalization-on-exit
4127 // + Call before_exit(), prepare for VM exit
4128 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4129 // currently the only user of this mechanism is File.deleteOnExit())
4130 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4131 // post thread end and vm death events to JVMTI,
4132 // stop signal thread
4133 // + Call JavaThread::exit(), it will:
4134 // > release JNI handle blocks, remove stack guard pages
4135 // > remove this thread from Threads list
4136 // <-- no more Java code from this thread after this point -->
4137 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4138 // the compiler threads at safepoint
4139 // <-- do not use anything that could get blocked by Safepoint -->
4140 // + Disable tracing at JNI/JVM barriers
4141 // + Set _vm_exited flag for threads that are still running native code
4142 // + Delete this thread
4143 // + Call exit_globals()
4144 // > deletes tty
4145 // > deletes PerfMemory resources
4146 // + Return to caller
4147
4148 bool Threads::destroy_vm() {
4149 JavaThread* thread = JavaThread::current();
4150
4151 #ifdef ASSERT
4152 _vm_complete = false;
4153 #endif
4154 // Wait until we are the last non-daemon thread to execute
4155 { MutexLocker nu(Threads_lock);
4156 while (Threads::number_of_non_daemon_threads() > 1)
4157 // This wait should make safepoint checks, wait without a timeout,
4158 // and wait as a suspend-equivalent condition.
4159 //
4160 // Note: If the FlatProfiler is running and this thread is waiting
4161 // for another non-daemon thread to finish, then the FlatProfiler
4162 // is waiting for the external suspend request on this thread to
4163 // complete. wait_for_ext_suspend_completion() will eventually
4164 // timeout, but that takes time. Making this wait a suspend-
4165 // equivalent condition solves that timeout problem.
4166 //
4167 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4168 Mutex::_as_suspend_equivalent_flag);
4169 }
4170
4171 // Hang forever on exit if we are reporting an error.
4172 if (ShowMessageBoxOnError && is_error_reported()) {
4173 os::infinite_sleep();
4174 }
4175 os::wait_for_keypress_at_exit();
4176
4177 // run Java level shutdown hooks
4178 thread->invoke_shutdown_hooks();
4179
4180 before_exit(thread);
4181
4182 thread->exit(true);
4183
4184 // Stop VM thread.
4185 {
4186 // 4945125 The vm thread comes to a safepoint during exit.
4187 // GC vm_operations can get caught at the safepoint, and the
4188 // heap is unparseable if they are caught. Grab the Heap_lock
4189 // to prevent this. The GC vm_operations will not be able to
4190 // queue until after the vm thread is dead. After this point,
4191 // we'll never emerge out of the safepoint before the VM exits.
4192
4193 MutexLocker ml(Heap_lock);
4194
4195 VMThread::wait_for_vm_thread_exit();
4196 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4197 VMThread::destroy();
4198 }
4199
4200 // clean up ideal graph printers
4201 #if defined(COMPILER2) && !defined(PRODUCT)
4202 IdealGraphPrinter::clean_up();
4203 #endif
4204
4205 // Now, all Java threads are gone except daemon threads. Daemon threads
4206 // running Java code or in VM are stopped by the Safepoint. However,
4207 // daemon threads executing native code are still running. But they
4208 // will be stopped at native=>Java/VM barriers. Note that we can't
4209 // simply kill or suspend them, as it is inherently deadlock-prone.
4210
4211 VM_Exit::set_vm_exited();
4212
4213 notify_vm_shutdown();
4214
4215 delete thread;
4216
4217 #if INCLUDE_JVMCI
4218 if (JVMCICounterSize > 0) {
4219 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4220 }
4221 #endif
4222
4223 // exit_globals() will delete tty
4224 exit_globals();
4225
4226 LogConfiguration::finalize();
4227
4228 return true;
4229 }
4230
4231
4232 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4233 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4234 return is_supported_jni_version(version);
4235 }
4236
4237
4238 jboolean Threads::is_supported_jni_version(jint version) {
4239 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4240 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4241 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4242 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4243 if (version == JNI_VERSION_9) return JNI_TRUE;
4244 return JNI_FALSE;
4245 }
4246
4247
4248 void Threads::add(JavaThread* p, bool force_daemon) {
4249 // The threads lock must be owned at this point
4250 assert_locked_or_safepoint(Threads_lock);
4251
4252 // See the comment for this method in thread.hpp for its purpose and
4253 // why it is called here.
4254 p->initialize_queues();
4255 p->set_next(_thread_list);
4256 _thread_list = p;
4257 _number_of_threads++;
4258 oop threadObj = p->threadObj();
4259 bool daemon = true;
4260 // Bootstrapping problem: threadObj can be null for initial
4261 // JavaThread (or for threads attached via JNI)
4262 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4263 _number_of_non_daemon_threads++;
4264 daemon = false;
4265 }
4266
4267 ThreadService::add_thread(p, daemon);
4268
4269 // Possible GC point.
4270 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4271 }
4272
4273 void Threads::remove(JavaThread* p) {
4274 // Extra scope needed for Thread_lock, so we can check
4275 // that we do not remove thread without safepoint code notice
4276 { MutexLocker ml(Threads_lock);
4277
4278 assert(includes(p), "p must be present");
4279
4280 JavaThread* current = _thread_list;
4281 JavaThread* prev = NULL;
4282
4283 while (current != p) {
4284 prev = current;
4285 current = current->next();
4286 }
4287
4288 if (prev) {
4289 prev->set_next(current->next());
4290 } else {
4291 _thread_list = p->next();
4292 }
4293 _number_of_threads--;
4294 oop threadObj = p->threadObj();
4295 bool daemon = true;
4296 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4297 _number_of_non_daemon_threads--;
4298 daemon = false;
4299
4300 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4301 // on destroy_vm will wake up.
4302 if (number_of_non_daemon_threads() == 1) {
4303 Threads_lock->notify_all();
4304 }
4305 }
4306 ThreadService::remove_thread(p, daemon);
4307
4308 // Make sure that safepoint code disregard this thread. This is needed since
4309 // the thread might mess around with locks after this point. This can cause it
4310 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4311 // of this thread since it is removed from the queue.
4312 p->set_terminated_value();
4313 } // unlock Threads_lock
4314
4315 // Since Events::log uses a lock, we grab it outside the Threads_lock
4316 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4317 }
4318
4319 // Threads_lock must be held when this is called (or must be called during a safepoint)
4320 bool Threads::includes(JavaThread* p) {
4321 assert(Threads_lock->is_locked(), "sanity check");
4322 ALL_JAVA_THREADS(q) {
4323 if (q == p) {
4324 return true;
4325 }
4326 }
4327 return false;
4328 }
4329
4330 // Operations on the Threads list for GC. These are not explicitly locked,
4331 // but the garbage collector must provide a safe context for them to run.
4332 // In particular, these things should never be called when the Threads_lock
4333 // is held by some other thread. (Note: the Safepoint abstraction also
4334 // uses the Threads_lock to guarantee this property. It also makes sure that
4335 // all threads gets blocked when exiting or starting).
4336
4337 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4338 ALL_JAVA_THREADS(p) {
4339 p->oops_do(f, cf);
4340 }
4341 VMThread::vm_thread()->oops_do(f, cf);
4342 }
4343
4344 void Threads::change_thread_claim_parity() {
4345 // Set the new claim parity.
4346 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4347 "Not in range.");
4348 _thread_claim_parity++;
4349 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4350 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4351 "Not in range.");
4352 }
4353
4354 #ifdef ASSERT
4355 void Threads::assert_all_threads_claimed() {
4356 ALL_JAVA_THREADS(p) {
4357 const int thread_parity = p->oops_do_parity();
4358 assert((thread_parity == _thread_claim_parity),
4359 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4360 }
4361 }
4362 #endif // ASSERT
4363
4364 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4365 int cp = Threads::thread_claim_parity();
4366 ALL_JAVA_THREADS(p) {
4367 if (p->claim_oops_do(is_par, cp)) {
4368 p->oops_do(f, cf);
4369 }
4370 }
4371 VMThread* vmt = VMThread::vm_thread();
4372 if (vmt->claim_oops_do(is_par, cp)) {
4373 vmt->oops_do(f, cf);
4374 }
4375 }
4376
4377 #if INCLUDE_ALL_GCS
4378 // Used by ParallelScavenge
4379 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4380 ALL_JAVA_THREADS(p) {
4381 q->enqueue(new ThreadRootsTask(p));
4382 }
4383 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4384 }
4385
4386 // Used by Parallel Old
4387 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4388 ALL_JAVA_THREADS(p) {
4389 q->enqueue(new ThreadRootsMarkingTask(p));
4390 }
4391 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4392 }
4393 #endif // INCLUDE_ALL_GCS
4394
4395 void Threads::nmethods_do(CodeBlobClosure* cf) {
4396 ALL_JAVA_THREADS(p) {
4397 // This is used by the code cache sweeper to mark nmethods that are active
4398 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4399 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4400 if(!p->is_Code_cache_sweeper_thread()) {
4401 p->nmethods_do(cf);
4402 }
4403 }
4404 }
4405
4406 void Threads::metadata_do(void f(Metadata*)) {
4407 ALL_JAVA_THREADS(p) {
4408 p->metadata_do(f);
4409 }
4410 }
4411
4412 class ThreadHandlesClosure : public ThreadClosure {
4413 void (*_f)(Metadata*);
4414 public:
4415 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4416 virtual void do_thread(Thread* thread) {
4417 thread->metadata_handles_do(_f);
4418 }
4419 };
4420
4421 void Threads::metadata_handles_do(void f(Metadata*)) {
4422 // Only walk the Handles in Thread.
4423 ThreadHandlesClosure handles_closure(f);
4424 threads_do(&handles_closure);
4425 }
4426
4427 void Threads::deoptimized_wrt_marked_nmethods() {
4428 ALL_JAVA_THREADS(p) {
4429 p->deoptimized_wrt_marked_nmethods();
4430 }
4431 }
4432
4433
4434 // Get count Java threads that are waiting to enter the specified monitor.
4435 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4436 address monitor,
4437 bool doLock) {
4438 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4439 "must grab Threads_lock or be at safepoint");
4440 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4441
4442 int i = 0;
4443 {
4444 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4445 ALL_JAVA_THREADS(p) {
4446 if (!p->can_call_java()) continue;
4447
4448 address pending = (address)p->current_pending_monitor();
4449 if (pending == monitor) { // found a match
4450 if (i < count) result->append(p); // save the first count matches
4451 i++;
4452 }
4453 }
4454 }
4455 return result;
4456 }
4457
4458
4459 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4460 bool doLock) {
4461 assert(doLock ||
4462 Threads_lock->owned_by_self() ||
4463 SafepointSynchronize::is_at_safepoint(),
4464 "must grab Threads_lock or be at safepoint");
4465
4466 // NULL owner means not locked so we can skip the search
4467 if (owner == NULL) return NULL;
4468
4469 {
4470 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4471 ALL_JAVA_THREADS(p) {
4472 // first, see if owner is the address of a Java thread
4473 if (owner == (address)p) return p;
4474 }
4475 }
4476 // Cannot assert on lack of success here since this function may be
4477 // used by code that is trying to report useful problem information
4478 // like deadlock detection.
4479 if (UseHeavyMonitors) return NULL;
4480
4481 // If we didn't find a matching Java thread and we didn't force use of
4482 // heavyweight monitors, then the owner is the stack address of the
4483 // Lock Word in the owning Java thread's stack.
4484 //
4485 JavaThread* the_owner = NULL;
4486 {
4487 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4488 ALL_JAVA_THREADS(q) {
4489 if (q->is_lock_owned(owner)) {
4490 the_owner = q;
4491 break;
4492 }
4493 }
4494 }
4495 // cannot assert on lack of success here; see above comment
4496 return the_owner;
4497 }
4498
4499 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4500 void Threads::print_on(outputStream* st, bool print_stacks,
4501 bool internal_format, bool print_concurrent_locks) {
4502 char buf[32];
4503 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4504
4505 st->print_cr("Full thread dump %s (%s %s):",
4506 Abstract_VM_Version::vm_name(),
4507 Abstract_VM_Version::vm_release(),
4508 Abstract_VM_Version::vm_info_string());
4509 st->cr();
4510
4511 #if INCLUDE_SERVICES
4512 // Dump concurrent locks
4513 ConcurrentLocksDump concurrent_locks;
4514 if (print_concurrent_locks) {
4515 concurrent_locks.dump_at_safepoint();
4516 }
4517 #endif // INCLUDE_SERVICES
4518
4519 ALL_JAVA_THREADS(p) {
4520 ResourceMark rm;
4521 p->print_on(st);
4522 if (print_stacks) {
4523 if (internal_format) {
4524 p->trace_stack();
4525 } else {
4526 p->print_stack_on(st);
4527 }
4528 }
4529 st->cr();
4530 #if INCLUDE_SERVICES
4531 if (print_concurrent_locks) {
4532 concurrent_locks.print_locks_on(p, st);
4533 }
4534 #endif // INCLUDE_SERVICES
4535 }
4536
4537 VMThread::vm_thread()->print_on(st);
4538 st->cr();
4539 Universe::heap()->print_gc_threads_on(st);
4540 WatcherThread* wt = WatcherThread::watcher_thread();
4541 if (wt != NULL) {
4542 wt->print_on(st);
4543 st->cr();
4544 }
4545 st->flush();
4546 }
4547
4548 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4549 int buflen, bool* found_current) {
4550 if (this_thread != NULL) {
4551 bool is_current = (current == this_thread);
4552 *found_current = *found_current || is_current;
4553 st->print("%s", is_current ? "=>" : " ");
4554
4555 st->print(PTR_FORMAT, p2i(this_thread));
4556 st->print(" ");
4557 this_thread->print_on_error(st, buf, buflen);
4558 st->cr();
4559 }
4560 }
4561
4562 class PrintOnErrorClosure : public ThreadClosure {
4563 outputStream* _st;
4564 Thread* _current;
4565 char* _buf;
4566 int _buflen;
4567 bool* _found_current;
4568 public:
4569 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4570 int buflen, bool* found_current) :
4571 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4572
4573 virtual void do_thread(Thread* thread) {
4574 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4575 }
4576 };
4577
4578 // Threads::print_on_error() is called by fatal error handler. It's possible
4579 // that VM is not at safepoint and/or current thread is inside signal handler.
4580 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4581 // memory (even in resource area), it might deadlock the error handler.
4582 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4583 int buflen) {
4584 bool found_current = false;
4585 st->print_cr("Java Threads: ( => current thread )");
4586 ALL_JAVA_THREADS(thread) {
4587 print_on_error(thread, st, current, buf, buflen, &found_current);
4588 }
4589 st->cr();
4590
4591 st->print_cr("Other Threads:");
4592 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4593 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4594
4595 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4596 Universe::heap()->gc_threads_do(&print_closure);
4597
4598 if (!found_current) {
4599 st->cr();
4600 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4601 current->print_on_error(st, buf, buflen);
4602 st->cr();
4603 }
4604 st->cr();
4605 st->print_cr("Threads with active compile tasks:");
4606 print_threads_compiling(st, buf, buflen);
4607 }
4608
4609 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4610 ALL_JAVA_THREADS(thread) {
4611 if (thread->is_Compiler_thread()) {
4612 CompilerThread* ct = (CompilerThread*) thread;
4613 if (ct->task() != NULL) {
4614 thread->print_name_on_error(st, buf, buflen);
4615 ct->task()->print(st, NULL, true, true);
4616 }
4617 }
4618 }
4619 }
4620
4621
4622 // Internal SpinLock and Mutex
4623 // Based on ParkEvent
4624
4625 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4626 //
4627 // We employ SpinLocks _only for low-contention, fixed-length
4628 // short-duration critical sections where we're concerned
4629 // about native mutex_t or HotSpot Mutex:: latency.
4630 // The mux construct provides a spin-then-block mutual exclusion
4631 // mechanism.
4632 //
4633 // Testing has shown that contention on the ListLock guarding gFreeList
4634 // is common. If we implement ListLock as a simple SpinLock it's common
4635 // for the JVM to devolve to yielding with little progress. This is true
4636 // despite the fact that the critical sections protected by ListLock are
4637 // extremely short.
4638 //
4639 // TODO-FIXME: ListLock should be of type SpinLock.
4640 // We should make this a 1st-class type, integrated into the lock
4641 // hierarchy as leaf-locks. Critically, the SpinLock structure
4642 // should have sufficient padding to avoid false-sharing and excessive
4643 // cache-coherency traffic.
4644
4645
4646 typedef volatile int SpinLockT;
4647
4648 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4649 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4650 return; // normal fast-path return
4651 }
4652
4653 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4654 TEVENT(SpinAcquire - ctx);
4655 int ctr = 0;
4656 int Yields = 0;
4657 for (;;) {
4658 while (*adr != 0) {
4659 ++ctr;
4660 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4661 if (Yields > 5) {
4662 os::naked_short_sleep(1);
4663 } else {
4664 os::naked_yield();
4665 ++Yields;
4666 }
4667 } else {
4668 SpinPause();
4669 }
4670 }
4671 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4672 }
4673 }
4674
4675 void Thread::SpinRelease(volatile int * adr) {
4676 assert(*adr != 0, "invariant");
4677 OrderAccess::fence(); // guarantee at least release consistency.
4678 // Roach-motel semantics.
4679 // It's safe if subsequent LDs and STs float "up" into the critical section,
4680 // but prior LDs and STs within the critical section can't be allowed
4681 // to reorder or float past the ST that releases the lock.
4682 // Loads and stores in the critical section - which appear in program
4683 // order before the store that releases the lock - must also appear
4684 // before the store that releases the lock in memory visibility order.
4685 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4686 // the ST of 0 into the lock-word which releases the lock, so fence
4687 // more than covers this on all platforms.
4688 *adr = 0;
4689 }
4690
4691 // muxAcquire and muxRelease:
4692 //
4693 // * muxAcquire and muxRelease support a single-word lock-word construct.
4694 // The LSB of the word is set IFF the lock is held.
4695 // The remainder of the word points to the head of a singly-linked list
4696 // of threads blocked on the lock.
4697 //
4698 // * The current implementation of muxAcquire-muxRelease uses its own
4699 // dedicated Thread._MuxEvent instance. If we're interested in
4700 // minimizing the peak number of extant ParkEvent instances then
4701 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4702 // as certain invariants were satisfied. Specifically, care would need
4703 // to be taken with regards to consuming unpark() "permits".
4704 // A safe rule of thumb is that a thread would never call muxAcquire()
4705 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4706 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4707 // consume an unpark() permit intended for monitorenter, for instance.
4708 // One way around this would be to widen the restricted-range semaphore
4709 // implemented in park(). Another alternative would be to provide
4710 // multiple instances of the PlatformEvent() for each thread. One
4711 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4712 //
4713 // * Usage:
4714 // -- Only as leaf locks
4715 // -- for short-term locking only as muxAcquire does not perform
4716 // thread state transitions.
4717 //
4718 // Alternatives:
4719 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4720 // but with parking or spin-then-park instead of pure spinning.
4721 // * Use Taura-Oyama-Yonenzawa locks.
4722 // * It's possible to construct a 1-0 lock if we encode the lockword as
4723 // (List,LockByte). Acquire will CAS the full lockword while Release
4724 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4725 // acquiring threads use timers (ParkTimed) to detect and recover from
4726 // the stranding window. Thread/Node structures must be aligned on 256-byte
4727 // boundaries by using placement-new.
4728 // * Augment MCS with advisory back-link fields maintained with CAS().
4729 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4730 // The validity of the backlinks must be ratified before we trust the value.
4731 // If the backlinks are invalid the exiting thread must back-track through the
4732 // the forward links, which are always trustworthy.
4733 // * Add a successor indication. The LockWord is currently encoded as
4734 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4735 // to provide the usual futile-wakeup optimization.
4736 // See RTStt for details.
4737 // * Consider schedctl.sc_nopreempt to cover the critical section.
4738 //
4739
4740
4741 typedef volatile intptr_t MutexT; // Mux Lock-word
4742 enum MuxBits { LOCKBIT = 1 };
4743
4744 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4745 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4746 if (w == 0) return;
4747 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4748 return;
4749 }
4750
4751 TEVENT(muxAcquire - Contention);
4752 ParkEvent * const Self = Thread::current()->_MuxEvent;
4753 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4754 for (;;) {
4755 int its = (os::is_MP() ? 100 : 0) + 1;
4756
4757 // Optional spin phase: spin-then-park strategy
4758 while (--its >= 0) {
4759 w = *Lock;
4760 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4761 return;
4762 }
4763 }
4764
4765 Self->reset();
4766 Self->OnList = intptr_t(Lock);
4767 // The following fence() isn't _strictly necessary as the subsequent
4768 // CAS() both serializes execution and ratifies the fetched *Lock value.
4769 OrderAccess::fence();
4770 for (;;) {
4771 w = *Lock;
4772 if ((w & LOCKBIT) == 0) {
4773 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4774 Self->OnList = 0; // hygiene - allows stronger asserts
4775 return;
4776 }
4777 continue; // Interference -- *Lock changed -- Just retry
4778 }
4779 assert(w & LOCKBIT, "invariant");
4780 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4781 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4782 }
4783
4784 while (Self->OnList != 0) {
4785 Self->park();
4786 }
4787 }
4788 }
4789
4790 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4791 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4792 if (w == 0) return;
4793 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4794 return;
4795 }
4796
4797 TEVENT(muxAcquire - Contention);
4798 ParkEvent * ReleaseAfter = NULL;
4799 if (ev == NULL) {
4800 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4801 }
4802 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4803 for (;;) {
4804 guarantee(ev->OnList == 0, "invariant");
4805 int its = (os::is_MP() ? 100 : 0) + 1;
4806
4807 // Optional spin phase: spin-then-park strategy
4808 while (--its >= 0) {
4809 w = *Lock;
4810 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4811 if (ReleaseAfter != NULL) {
4812 ParkEvent::Release(ReleaseAfter);
4813 }
4814 return;
4815 }
4816 }
4817
4818 ev->reset();
4819 ev->OnList = intptr_t(Lock);
4820 // The following fence() isn't _strictly necessary as the subsequent
4821 // CAS() both serializes execution and ratifies the fetched *Lock value.
4822 OrderAccess::fence();
4823 for (;;) {
4824 w = *Lock;
4825 if ((w & LOCKBIT) == 0) {
4826 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4827 ev->OnList = 0;
4828 // We call ::Release while holding the outer lock, thus
4829 // artificially lengthening the critical section.
4830 // Consider deferring the ::Release() until the subsequent unlock(),
4831 // after we've dropped the outer lock.
4832 if (ReleaseAfter != NULL) {
4833 ParkEvent::Release(ReleaseAfter);
4834 }
4835 return;
4836 }
4837 continue; // Interference -- *Lock changed -- Just retry
4838 }
4839 assert(w & LOCKBIT, "invariant");
4840 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4841 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4842 }
4843
4844 while (ev->OnList != 0) {
4845 ev->park();
4846 }
4847 }
4848 }
4849
4850 // Release() must extract a successor from the list and then wake that thread.
4851 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4852 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4853 // Release() would :
4854 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4855 // (B) Extract a successor from the private list "in-hand"
4856 // (C) attempt to CAS() the residual back into *Lock over null.
4857 // If there were any newly arrived threads and the CAS() would fail.
4858 // In that case Release() would detach the RATs, re-merge the list in-hand
4859 // with the RATs and repeat as needed. Alternately, Release() might
4860 // detach and extract a successor, but then pass the residual list to the wakee.
4861 // The wakee would be responsible for reattaching and remerging before it
4862 // competed for the lock.
4863 //
4864 // Both "pop" and DMR are immune from ABA corruption -- there can be
4865 // multiple concurrent pushers, but only one popper or detacher.
4866 // This implementation pops from the head of the list. This is unfair,
4867 // but tends to provide excellent throughput as hot threads remain hot.
4868 // (We wake recently run threads first).
4869 //
4870 // All paths through muxRelease() will execute a CAS.
4871 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4872 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4873 // executed within the critical section are complete and globally visible before the
4874 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4875 void Thread::muxRelease(volatile intptr_t * Lock) {
4876 for (;;) {
4877 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4878 assert(w & LOCKBIT, "invariant");
4879 if (w == LOCKBIT) return;
4880 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4881 assert(List != NULL, "invariant");
4882 assert(List->OnList == intptr_t(Lock), "invariant");
4883 ParkEvent * const nxt = List->ListNext;
4884 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4885
4886 // The following CAS() releases the lock and pops the head element.
4887 // The CAS() also ratifies the previously fetched lock-word value.
4888 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4889 continue;
4890 }
4891 List->OnList = 0;
4892 OrderAccess::fence();
4893 List->unpark();
4894 return;
4895 }
4896 }
4897
4898
4899 void Threads::verify() {
4900 ALL_JAVA_THREADS(p) {
4901 p->verify();
4902 }
4903 VMThread* thread = VMThread::vm_thread();
4904 if (thread != NULL) thread->verify();
4905 }