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