1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/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 instanceKlassHandle klass (THREAD, k);
954
955 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
956 {
957 JavaValue result(T_VOID);
958 JavaCalls::call_special(&result,
959 system_instance,
960 klass,
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 = klass->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 klass,
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 instanceKlassHandle klass (THREAD, k);
988 instanceHandle thread_oop = klass->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 klass,
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* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1058 instanceKlassHandle klass (THREAD, k);
1059 if (klass.not_null()) {
1060 JavaValue result(T_VOID);
1061 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1062 vmSymbols::void_method_signature(),
1063 CHECK);
1064 }
1065 }
1066
1067 static void reset_vm_info_property(TRAPS) {
1068 // the vm info string
1069 ResourceMark rm(THREAD);
1070 const char *vm_info = VM_Version::vm_info_string();
1071
1072 // java.lang.System class
1073 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1074 instanceKlassHandle klass (THREAD, k);
1075
1076 // setProperty arguments
1077 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1078 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1079
1080 // return value
1081 JavaValue r(T_OBJECT);
1082
1083 // public static String setProperty(String key, String value);
1084 JavaCalls::call_static(&r,
1085 klass,
1086 vmSymbols::setProperty_name(),
1087 vmSymbols::string_string_string_signature(),
1088 key_str,
1089 value_str,
1090 CHECK);
1091 }
1092
1093
1094 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1095 bool daemon, TRAPS) {
1096 assert(thread_group.not_null(), "thread group should be specified");
1097 assert(threadObj() == NULL, "should only create Java thread object once");
1098
1099 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1100 instanceKlassHandle klass (THREAD, k);
1101 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1102
1103 java_lang_Thread::set_thread(thread_oop(), this);
1104 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1105 set_threadObj(thread_oop());
1106
1107 JavaValue result(T_VOID);
1108 if (thread_name != NULL) {
1109 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1110 // Thread gets assigned specified name and null target
1111 JavaCalls::call_special(&result,
1112 thread_oop,
1113 klass,
1114 vmSymbols::object_initializer_name(),
1115 vmSymbols::threadgroup_string_void_signature(),
1116 thread_group, // Argument 1
1117 name, // Argument 2
1118 THREAD);
1119 } else {
1120 // Thread gets assigned name "Thread-nnn" and null target
1121 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1122 JavaCalls::call_special(&result,
1123 thread_oop,
1124 klass,
1125 vmSymbols::object_initializer_name(),
1126 vmSymbols::threadgroup_runnable_void_signature(),
1127 thread_group, // Argument 1
1128 Handle(), // Argument 2
1129 THREAD);
1130 }
1131
1132
1133 if (daemon) {
1134 java_lang_Thread::set_daemon(thread_oop());
1135 }
1136
1137 if (HAS_PENDING_EXCEPTION) {
1138 return;
1139 }
1140
1141 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1142 Handle threadObj(THREAD, this->threadObj());
1143
1144 JavaCalls::call_special(&result,
1145 thread_group,
1146 group,
1147 vmSymbols::add_method_name(),
1148 vmSymbols::thread_void_signature(),
1149 threadObj, // Arg 1
1150 THREAD);
1151 }
1152
1153 // NamedThread -- non-JavaThread subclasses with multiple
1154 // uniquely named instances should derive from this.
1155 NamedThread::NamedThread() : Thread() {
1156 _name = NULL;
1157 _processed_thread = NULL;
1158 _gc_id = GCId::undefined();
1159 }
1160
1161 NamedThread::~NamedThread() {
1162 if (_name != NULL) {
1163 FREE_C_HEAP_ARRAY(char, _name);
1164 _name = NULL;
1165 }
1166 }
1167
1168 void NamedThread::set_name(const char* format, ...) {
1169 guarantee(_name == NULL, "Only get to set name once.");
1170 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1171 guarantee(_name != NULL, "alloc failure");
1172 va_list ap;
1173 va_start(ap, format);
1174 jio_vsnprintf(_name, max_name_len, format, ap);
1175 va_end(ap);
1176 }
1177
1178 void NamedThread::initialize_named_thread() {
1179 set_native_thread_name(name());
1180 }
1181
1182 void NamedThread::print_on(outputStream* st) const {
1183 st->print("\"%s\" ", name());
1184 Thread::print_on(st);
1185 st->cr();
1186 }
1187
1188
1189 // ======= WatcherThread ========
1190
1191 // The watcher thread exists to simulate timer interrupts. It should
1192 // be replaced by an abstraction over whatever native support for
1193 // timer interrupts exists on the platform.
1194
1195 WatcherThread* WatcherThread::_watcher_thread = NULL;
1196 bool WatcherThread::_startable = false;
1197 volatile bool WatcherThread::_should_terminate = false;
1198
1199 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1200 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1201 if (os::create_thread(this, os::watcher_thread)) {
1202 _watcher_thread = this;
1203
1204 // Set the watcher thread to the highest OS priority which should not be
1205 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1206 // is created. The only normal thread using this priority is the reference
1207 // handler thread, which runs for very short intervals only.
1208 // If the VMThread's priority is not lower than the WatcherThread profiling
1209 // will be inaccurate.
1210 os::set_priority(this, MaxPriority);
1211 if (!DisableStartThread) {
1212 os::start_thread(this);
1213 }
1214 }
1215 }
1216
1217 int WatcherThread::sleep() const {
1218 // The WatcherThread does not participate in the safepoint protocol
1219 // for the PeriodicTask_lock because it is not a JavaThread.
1220 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1221
1222 if (_should_terminate) {
1223 // check for termination before we do any housekeeping or wait
1224 return 0; // we did not sleep.
1225 }
1226
1227 // remaining will be zero if there are no tasks,
1228 // causing the WatcherThread to sleep until a task is
1229 // enrolled
1230 int remaining = PeriodicTask::time_to_wait();
1231 int time_slept = 0;
1232
1233 // we expect this to timeout - we only ever get unparked when
1234 // we should terminate or when a new task has been enrolled
1235 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1236
1237 jlong time_before_loop = os::javaTimeNanos();
1238
1239 while (true) {
1240 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1241 remaining);
1242 jlong now = os::javaTimeNanos();
1243
1244 if (remaining == 0) {
1245 // if we didn't have any tasks we could have waited for a long time
1246 // consider the time_slept zero and reset time_before_loop
1247 time_slept = 0;
1248 time_before_loop = now;
1249 } else {
1250 // need to recalculate since we might have new tasks in _tasks
1251 time_slept = (int) ((now - time_before_loop) / 1000000);
1252 }
1253
1254 // Change to task list or spurious wakeup of some kind
1255 if (timedout || _should_terminate) {
1256 break;
1257 }
1258
1259 remaining = PeriodicTask::time_to_wait();
1260 if (remaining == 0) {
1261 // Last task was just disenrolled so loop around and wait until
1262 // another task gets enrolled
1263 continue;
1264 }
1265
1266 remaining -= time_slept;
1267 if (remaining <= 0) {
1268 break;
1269 }
1270 }
1271
1272 return time_slept;
1273 }
1274
1275 void WatcherThread::run() {
1276 assert(this == watcher_thread(), "just checking");
1277
1278 this->record_stack_base_and_size();
1279 this->set_native_thread_name(this->name());
1280 this->set_active_handles(JNIHandleBlock::allocate_block());
1281 while (true) {
1282 assert(watcher_thread() == Thread::current(), "thread consistency check");
1283 assert(watcher_thread() == this, "thread consistency check");
1284
1285 // Calculate how long it'll be until the next PeriodicTask work
1286 // should be done, and sleep that amount of time.
1287 int time_waited = sleep();
1288
1289 if (is_error_reported()) {
1290 // A fatal error has happened, the error handler(VMError::report_and_die)
1291 // should abort JVM after creating an error log file. However in some
1292 // rare cases, the error handler itself might deadlock. Here we try to
1293 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1294 //
1295 // This code is in WatcherThread because WatcherThread wakes up
1296 // periodically so the fatal error handler doesn't need to do anything;
1297 // also because the WatcherThread is less likely to crash than other
1298 // threads.
1299
1300 for (;;) {
1301 if (!ShowMessageBoxOnError
1302 && (OnError == NULL || OnError[0] == '\0')
1303 && Arguments::abort_hook() == NULL) {
1304 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1305 fdStream err(defaultStream::output_fd());
1306 err.print_raw_cr("# [ timer expired, abort... ]");
1307 // skip atexit/vm_exit/vm_abort hooks
1308 os::die();
1309 }
1310
1311 // Wake up 5 seconds later, the fatal handler may reset OnError or
1312 // ShowMessageBoxOnError when it is ready to abort.
1313 os::sleep(this, 5 * 1000, false);
1314 }
1315 }
1316
1317 if (_should_terminate) {
1318 // check for termination before posting the next tick
1319 break;
1320 }
1321
1322 PeriodicTask::real_time_tick(time_waited);
1323 }
1324
1325 // Signal that it is terminated
1326 {
1327 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1328 _watcher_thread = NULL;
1329 Terminator_lock->notify();
1330 }
1331 }
1332
1333 void WatcherThread::start() {
1334 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1335
1336 if (watcher_thread() == NULL && _startable) {
1337 _should_terminate = false;
1338 // Create the single instance of WatcherThread
1339 new WatcherThread();
1340 }
1341 }
1342
1343 void WatcherThread::make_startable() {
1344 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1345 _startable = true;
1346 }
1347
1348 void WatcherThread::stop() {
1349 {
1350 // Follow normal safepoint aware lock enter protocol since the
1351 // WatcherThread is stopped by another JavaThread.
1352 MutexLocker ml(PeriodicTask_lock);
1353 _should_terminate = true;
1354
1355 WatcherThread* watcher = watcher_thread();
1356 if (watcher != NULL) {
1357 // unpark the WatcherThread so it can see that it should terminate
1358 watcher->unpark();
1359 }
1360 }
1361
1362 MutexLocker mu(Terminator_lock);
1363
1364 while (watcher_thread() != NULL) {
1365 // This wait should make safepoint checks, wait without a timeout,
1366 // and wait as a suspend-equivalent condition.
1367 //
1368 // Note: If the FlatProfiler is running, then this thread is waiting
1369 // for the WatcherThread to terminate and the WatcherThread, via the
1370 // FlatProfiler task, is waiting for the external suspend request on
1371 // this thread to complete. wait_for_ext_suspend_completion() will
1372 // eventually timeout, but that takes time. Making this wait a
1373 // suspend-equivalent condition solves that timeout problem.
1374 //
1375 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1376 Mutex::_as_suspend_equivalent_flag);
1377 }
1378 }
1379
1380 void WatcherThread::unpark() {
1381 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1382 PeriodicTask_lock->notify();
1383 }
1384
1385 void WatcherThread::print_on(outputStream* st) const {
1386 st->print("\"%s\" ", name());
1387 Thread::print_on(st);
1388 st->cr();
1389 }
1390
1391 // ======= JavaThread ========
1392
1393 #if INCLUDE_JVMCI
1394
1395 jlong* JavaThread::_jvmci_old_thread_counters;
1396
1397 bool jvmci_counters_include(JavaThread* thread) {
1398 oop threadObj = thread->threadObj();
1399 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1400 }
1401
1402 void JavaThread::collect_counters(typeArrayOop array) {
1403 if (JVMCICounterSize > 0) {
1404 MutexLocker tl(Threads_lock);
1405 for (int i = 0; i < array->length(); i++) {
1406 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1407 }
1408 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1409 if (jvmci_counters_include(tp)) {
1410 for (int i = 0; i < array->length(); i++) {
1411 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1412 }
1413 }
1414 }
1415 }
1416 }
1417
1418 #endif // INCLUDE_JVMCI
1419
1420 // A JavaThread is a normal Java thread
1421
1422 void JavaThread::initialize() {
1423 // Initialize fields
1424
1425 set_saved_exception_pc(NULL);
1426 set_threadObj(NULL);
1427 _anchor.clear();
1428 set_entry_point(NULL);
1429 set_jni_functions(jni_functions());
1430 set_callee_target(NULL);
1431 set_vm_result(NULL);
1432 set_vm_result_2(NULL);
1433 set_vframe_array_head(NULL);
1434 set_vframe_array_last(NULL);
1435 set_deferred_locals(NULL);
1436 set_deopt_mark(NULL);
1437 set_deopt_compiled_method(NULL);
1438 clear_must_deopt_id();
1439 set_monitor_chunks(NULL);
1440 set_next(NULL);
1441 set_thread_state(_thread_new);
1442 _terminated = _not_terminated;
1443 _privileged_stack_top = NULL;
1444 _array_for_gc = NULL;
1445 _suspend_equivalent = false;
1446 _in_deopt_handler = 0;
1447 _doing_unsafe_access = false;
1448 _stack_guard_state = stack_guard_unused;
1449 #if INCLUDE_JVMCI
1450 _pending_monitorenter = false;
1451 _pending_deoptimization = -1;
1452 _pending_failed_speculation = NULL;
1453 _pending_transfer_to_interpreter = false;
1454 _adjusting_comp_level = false;
1455 _jvmci._alternate_call_target = NULL;
1456 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1457 if (JVMCICounterSize > 0) {
1458 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1459 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1460 } else {
1461 _jvmci_counters = NULL;
1462 }
1463 #endif // INCLUDE_JVMCI
1464 _reserved_stack_activation = NULL; // stack base not known yet
1465 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1466 _exception_pc = 0;
1467 _exception_handler_pc = 0;
1468 _is_method_handle_return = 0;
1469 _jvmti_thread_state= NULL;
1470 _should_post_on_exceptions_flag = JNI_FALSE;
1471 _jvmti_get_loaded_classes_closure = NULL;
1472 _interp_only_mode = 0;
1473 _special_runtime_exit_condition = _no_async_condition;
1474 _pending_async_exception = NULL;
1475 _thread_stat = NULL;
1476 _thread_stat = new ThreadStatistics();
1477 _blocked_on_compilation = false;
1478 _jni_active_critical = 0;
1479 _pending_jni_exception_check_fn = NULL;
1480 _do_not_unlock_if_synchronized = false;
1481 _cached_monitor_info = NULL;
1482 _parker = Parker::Allocate(this);
1483 _bytes_until_sample = 0;
1484
1485 #ifndef PRODUCT
1486 _jmp_ring_index = 0;
1487 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1488 record_jump(NULL, NULL, NULL, 0);
1489 }
1490 #endif // PRODUCT
1491
1492 set_thread_profiler(NULL);
1493 if (FlatProfiler::is_active()) {
1494 // This is where we would decide to either give each thread it's own profiler
1495 // or use one global one from FlatProfiler,
1496 // or up to some count of the number of profiled threads, etc.
1497 ThreadProfiler* pp = new ThreadProfiler();
1498 pp->engage();
1499 set_thread_profiler(pp);
1500 }
1501
1502 // Setup safepoint state info for this thread
1503 ThreadSafepointState::create(this);
1504
1505 debug_only(_java_call_counter = 0);
1506
1507 // JVMTI PopFrame support
1508 _popframe_condition = popframe_inactive;
1509 _popframe_preserved_args = NULL;
1510 _popframe_preserved_args_size = 0;
1511 _frames_to_pop_failed_realloc = 0;
1512
1513 pd_initialize();
1514 }
1515
1516 #if INCLUDE_ALL_GCS
1517 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1518 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1519 #endif // INCLUDE_ALL_GCS
1520
1521 JavaThread::JavaThread(bool is_attaching_via_jni) :
1522 Thread()
1523 #if INCLUDE_ALL_GCS
1524 , _satb_mark_queue(&_satb_mark_queue_set),
1525 _dirty_card_queue(&_dirty_card_queue_set)
1526 #endif // INCLUDE_ALL_GCS
1527 {
1528 initialize();
1529 if (is_attaching_via_jni) {
1530 _jni_attach_state = _attaching_via_jni;
1531 } else {
1532 _jni_attach_state = _not_attaching_via_jni;
1533 }
1534 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1535 }
1536
1537 bool JavaThread::reguard_stack(address cur_sp) {
1538 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1539 && _stack_guard_state != stack_guard_reserved_disabled) {
1540 return true; // Stack already guarded or guard pages not needed.
1541 }
1542
1543 if (register_stack_overflow()) {
1544 // For those architectures which have separate register and
1545 // memory stacks, we must check the register stack to see if
1546 // it has overflowed.
1547 return false;
1548 }
1549
1550 // Java code never executes within the yellow zone: the latter is only
1551 // there to provoke an exception during stack banging. If java code
1552 // is executing there, either StackShadowPages should be larger, or
1553 // some exception code in c1, c2 or the interpreter isn't unwinding
1554 // when it should.
1555 guarantee(cur_sp > stack_reserved_zone_base(),
1556 "not enough space to reguard - increase StackShadowPages");
1557 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1558 enable_stack_yellow_reserved_zone();
1559 if (reserved_stack_activation() != stack_base()) {
1560 set_reserved_stack_activation(stack_base());
1561 }
1562 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1563 set_reserved_stack_activation(stack_base());
1564 enable_stack_reserved_zone();
1565 }
1566 return true;
1567 }
1568
1569 bool JavaThread::reguard_stack(void) {
1570 return reguard_stack(os::current_stack_pointer());
1571 }
1572
1573
1574 void JavaThread::block_if_vm_exited() {
1575 if (_terminated == _vm_exited) {
1576 // _vm_exited is set at safepoint, and Threads_lock is never released
1577 // we will block here forever
1578 Threads_lock->lock_without_safepoint_check();
1579 ShouldNotReachHere();
1580 }
1581 }
1582
1583
1584 // Remove this ifdef when C1 is ported to the compiler interface.
1585 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1586 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1587
1588 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1589 Thread()
1590 #if INCLUDE_ALL_GCS
1591 , _satb_mark_queue(&_satb_mark_queue_set),
1592 _dirty_card_queue(&_dirty_card_queue_set)
1593 #endif // INCLUDE_ALL_GCS
1594 {
1595 initialize();
1596 _jni_attach_state = _not_attaching_via_jni;
1597 set_entry_point(entry_point);
1598 // Create the native thread itself.
1599 // %note runtime_23
1600 os::ThreadType thr_type = os::java_thread;
1601 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1602 os::java_thread;
1603 os::create_thread(this, thr_type, stack_sz);
1604 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1605 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1606 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1607 // the exception consists of creating the exception object & initializing it, initialization
1608 // will leave the VM via a JavaCall and then all locks must be unlocked).
1609 //
1610 // The thread is still suspended when we reach here. Thread must be explicit started
1611 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1612 // by calling Threads:add. The reason why this is not done here, is because the thread
1613 // object must be fully initialized (take a look at JVM_Start)
1614 }
1615
1616 JavaThread::~JavaThread() {
1617
1618 // JSR166 -- return the parker to the free list
1619 Parker::Release(_parker);
1620 _parker = NULL;
1621
1622 // Free any remaining previous UnrollBlock
1623 vframeArray* old_array = vframe_array_last();
1624
1625 if (old_array != NULL) {
1626 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1627 old_array->set_unroll_block(NULL);
1628 delete old_info;
1629 delete old_array;
1630 }
1631
1632 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1633 if (deferred != NULL) {
1634 // This can only happen if thread is destroyed before deoptimization occurs.
1635 assert(deferred->length() != 0, "empty array!");
1636 do {
1637 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1638 deferred->remove_at(0);
1639 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1640 delete dlv;
1641 } while (deferred->length() != 0);
1642 delete deferred;
1643 }
1644
1645 // All Java related clean up happens in exit
1646 ThreadSafepointState::destroy(this);
1647 if (_thread_profiler != NULL) delete _thread_profiler;
1648 if (_thread_stat != NULL) delete _thread_stat;
1649
1650 #if INCLUDE_JVMCI
1651 if (JVMCICounterSize > 0) {
1652 if (jvmci_counters_include(this)) {
1653 for (int i = 0; i < JVMCICounterSize; i++) {
1654 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1655 }
1656 }
1657 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1658 }
1659 #endif // INCLUDE_JVMCI
1660 }
1661
1662
1663 // The first routine called by a new Java thread
1664 void JavaThread::run() {
1665 // initialize thread-local alloc buffer related fields
1666 this->initialize_tlab();
1667
1668 // used to test validity of stack trace backs
1669 this->record_base_of_stack_pointer();
1670
1671 // Record real stack base and size.
1672 this->record_stack_base_and_size();
1673
1674 this->create_stack_guard_pages();
1675
1676 this->cache_global_variables();
1677
1678 // Thread is now sufficient initialized to be handled by the safepoint code as being
1679 // in the VM. Change thread state from _thread_new to _thread_in_vm
1680 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1681
1682 assert(JavaThread::current() == this, "sanity check");
1683 assert(!Thread::current()->owns_locks(), "sanity check");
1684
1685 DTRACE_THREAD_PROBE(start, this);
1686
1687 // This operation might block. We call that after all safepoint checks for a new thread has
1688 // been completed.
1689 this->set_active_handles(JNIHandleBlock::allocate_block());
1690
1691 if (JvmtiExport::should_post_thread_life()) {
1692 JvmtiExport::post_thread_start(this);
1693 }
1694
1695 EventThreadStart event;
1696 if (event.should_commit()) {
1697 event.set_thread(THREAD_TRACE_ID(this));
1698 event.commit();
1699 }
1700
1701 // We call another function to do the rest so we are sure that the stack addresses used
1702 // from there will be lower than the stack base just computed
1703 thread_main_inner();
1704
1705 // Note, thread is no longer valid at this point!
1706 }
1707
1708
1709 void JavaThread::thread_main_inner() {
1710 assert(JavaThread::current() == this, "sanity check");
1711 assert(this->threadObj() != NULL, "just checking");
1712
1713 // Execute thread entry point unless this thread has a pending exception
1714 // or has been stopped before starting.
1715 // Note: Due to JVM_StopThread we can have pending exceptions already!
1716 if (!this->has_pending_exception() &&
1717 !java_lang_Thread::is_stillborn(this->threadObj())) {
1718 {
1719 ResourceMark rm(this);
1720 this->set_native_thread_name(this->get_thread_name());
1721 }
1722 HandleMark hm(this);
1723 this->entry_point()(this, this);
1724 }
1725
1726 DTRACE_THREAD_PROBE(stop, this);
1727
1728 this->exit(false);
1729 delete this;
1730 }
1731
1732
1733 static void ensure_join(JavaThread* thread) {
1734 // We do not need to grap the Threads_lock, since we are operating on ourself.
1735 Handle threadObj(thread, thread->threadObj());
1736 assert(threadObj.not_null(), "java thread object must exist");
1737 ObjectLocker lock(threadObj, thread);
1738 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1739 thread->clear_pending_exception();
1740 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1741 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1742 // Clear the native thread instance - this makes isAlive return false and allows the join()
1743 // to complete once we've done the notify_all below
1744 java_lang_Thread::set_thread(threadObj(), NULL);
1745 lock.notify_all(thread);
1746 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1747 thread->clear_pending_exception();
1748 }
1749
1750
1751 // For any new cleanup additions, please check to see if they need to be applied to
1752 // cleanup_failed_attach_current_thread as well.
1753 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1754 assert(this == JavaThread::current(), "thread consistency check");
1755
1756 HandleMark hm(this);
1757 Handle uncaught_exception(this, this->pending_exception());
1758 this->clear_pending_exception();
1759 Handle threadObj(this, this->threadObj());
1760 assert(threadObj.not_null(), "Java thread object should be created");
1761
1762 if (get_thread_profiler() != NULL) {
1763 get_thread_profiler()->disengage();
1764 ResourceMark rm;
1765 get_thread_profiler()->print(get_thread_name());
1766 }
1767
1768
1769 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1770 {
1771 EXCEPTION_MARK;
1772
1773 CLEAR_PENDING_EXCEPTION;
1774 }
1775 if (!destroy_vm) {
1776 if (uncaught_exception.not_null()) {
1777 EXCEPTION_MARK;
1778 // Call method Thread.dispatchUncaughtException().
1779 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1780 JavaValue result(T_VOID);
1781 JavaCalls::call_virtual(&result,
1782 threadObj, thread_klass,
1783 vmSymbols::dispatchUncaughtException_name(),
1784 vmSymbols::throwable_void_signature(),
1785 uncaught_exception,
1786 THREAD);
1787 if (HAS_PENDING_EXCEPTION) {
1788 ResourceMark rm(this);
1789 jio_fprintf(defaultStream::error_stream(),
1790 "\nException: %s thrown from the UncaughtExceptionHandler"
1791 " in thread \"%s\"\n",
1792 pending_exception()->klass()->external_name(),
1793 get_thread_name());
1794 CLEAR_PENDING_EXCEPTION;
1795 }
1796 }
1797
1798 // Called before the java thread exit since we want to read info
1799 // from java_lang_Thread object
1800 EventThreadEnd event;
1801 if (event.should_commit()) {
1802 event.set_thread(THREAD_TRACE_ID(this));
1803 event.commit();
1804 }
1805
1806 // Call after last event on thread
1807 EVENT_THREAD_EXIT(this);
1808
1809 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1810 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1811 // is deprecated anyhow.
1812 if (!is_Compiler_thread()) {
1813 int count = 3;
1814 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1815 EXCEPTION_MARK;
1816 JavaValue result(T_VOID);
1817 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1818 JavaCalls::call_virtual(&result,
1819 threadObj, thread_klass,
1820 vmSymbols::exit_method_name(),
1821 vmSymbols::void_method_signature(),
1822 THREAD);
1823 CLEAR_PENDING_EXCEPTION;
1824 }
1825 }
1826 // notify JVMTI
1827 if (JvmtiExport::should_post_thread_life()) {
1828 JvmtiExport::post_thread_end(this);
1829 }
1830
1831 // We have notified the agents that we are exiting, before we go on,
1832 // we must check for a pending external suspend request and honor it
1833 // in order to not surprise the thread that made the suspend request.
1834 while (true) {
1835 {
1836 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1837 if (!is_external_suspend()) {
1838 set_terminated(_thread_exiting);
1839 ThreadService::current_thread_exiting(this);
1840 break;
1841 }
1842 // Implied else:
1843 // Things get a little tricky here. We have a pending external
1844 // suspend request, but we are holding the SR_lock so we
1845 // can't just self-suspend. So we temporarily drop the lock
1846 // and then self-suspend.
1847 }
1848
1849 ThreadBlockInVM tbivm(this);
1850 java_suspend_self();
1851
1852 // We're done with this suspend request, but we have to loop around
1853 // and check again. Eventually we will get SR_lock without a pending
1854 // external suspend request and will be able to mark ourselves as
1855 // exiting.
1856 }
1857 // no more external suspends are allowed at this point
1858 } else {
1859 // before_exit() has already posted JVMTI THREAD_END events
1860 }
1861
1862 // Notify waiters on thread object. This has to be done after exit() is called
1863 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1864 // group should have the destroyed bit set before waiters are notified).
1865 ensure_join(this);
1866 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1867
1868 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1869 // held by this thread must be released. The spec does not distinguish
1870 // between JNI-acquired and regular Java monitors. We can only see
1871 // regular Java monitors here if monitor enter-exit matching is broken.
1872 //
1873 // Optionally release any monitors for regular JavaThread exits. This
1874 // is provided as a work around for any bugs in monitor enter-exit
1875 // matching. This can be expensive so it is not enabled by default.
1876 //
1877 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1878 // ObjectSynchronizer::release_monitors_owned_by_thread().
1879 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1880 // Sanity check even though JNI DetachCurrentThread() would have
1881 // returned JNI_ERR if there was a Java frame. JavaThread exit
1882 // should be done executing Java code by the time we get here.
1883 assert(!this->has_last_Java_frame(),
1884 "should not have a Java frame when detaching or exiting");
1885 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1886 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1887 }
1888
1889 // These things needs to be done while we are still a Java Thread. Make sure that thread
1890 // is in a consistent state, in case GC happens
1891 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1892
1893 if (active_handles() != NULL) {
1894 JNIHandleBlock* block = active_handles();
1895 set_active_handles(NULL);
1896 JNIHandleBlock::release_block(block);
1897 }
1898
1899 if (free_handle_block() != NULL) {
1900 JNIHandleBlock* block = free_handle_block();
1901 set_free_handle_block(NULL);
1902 JNIHandleBlock::release_block(block);
1903 }
1904
1905 // These have to be removed while this is still a valid thread.
1906 remove_stack_guard_pages();
1907
1908 if (UseTLAB) {
1909 tlab().make_parsable(true); // retire TLAB
1910 }
1911
1912 if (JvmtiEnv::environments_might_exist()) {
1913 JvmtiExport::cleanup_thread(this);
1914 }
1915
1916 // We must flush any deferred card marks before removing a thread from
1917 // the list of active threads.
1918 Universe::heap()->flush_deferred_store_barrier(this);
1919 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1920
1921 #if INCLUDE_ALL_GCS
1922 // We must flush the G1-related buffers before removing a thread
1923 // from the list of active threads. We must do this after any deferred
1924 // card marks have been flushed (above) so that any entries that are
1925 // added to the thread's dirty card queue as a result are not lost.
1926 if (UseG1GC) {
1927 flush_barrier_queues();
1928 }
1929 #endif // INCLUDE_ALL_GCS
1930
1931 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1932 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1933 os::current_thread_id());
1934
1935 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1936 Threads::remove(this);
1937 }
1938
1939 #if INCLUDE_ALL_GCS
1940 // Flush G1-related queues.
1941 void JavaThread::flush_barrier_queues() {
1942 satb_mark_queue().flush();
1943 dirty_card_queue().flush();
1944 }
1945
1946 void JavaThread::initialize_queues() {
1947 assert(!SafepointSynchronize::is_at_safepoint(),
1948 "we should not be at a safepoint");
1949
1950 SATBMarkQueue& satb_queue = satb_mark_queue();
1951 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1952 // The SATB queue should have been constructed with its active
1953 // field set to false.
1954 assert(!satb_queue.is_active(), "SATB queue should not be active");
1955 assert(satb_queue.is_empty(), "SATB queue should be empty");
1956 // If we are creating the thread during a marking cycle, we should
1957 // set the active field of the SATB queue to true.
1958 if (satb_queue_set.is_active()) {
1959 satb_queue.set_active(true);
1960 }
1961
1962 DirtyCardQueue& dirty_queue = dirty_card_queue();
1963 // The dirty card queue should have been constructed with its
1964 // active field set to true.
1965 assert(dirty_queue.is_active(), "dirty card queue should be active");
1966 }
1967 #endif // INCLUDE_ALL_GCS
1968
1969 void JavaThread::cleanup_failed_attach_current_thread() {
1970 if (get_thread_profiler() != NULL) {
1971 get_thread_profiler()->disengage();
1972 ResourceMark rm;
1973 get_thread_profiler()->print(get_thread_name());
1974 }
1975
1976 if (active_handles() != NULL) {
1977 JNIHandleBlock* block = active_handles();
1978 set_active_handles(NULL);
1979 JNIHandleBlock::release_block(block);
1980 }
1981
1982 if (free_handle_block() != NULL) {
1983 JNIHandleBlock* block = free_handle_block();
1984 set_free_handle_block(NULL);
1985 JNIHandleBlock::release_block(block);
1986 }
1987
1988 // These have to be removed while this is still a valid thread.
1989 remove_stack_guard_pages();
1990
1991 if (UseTLAB) {
1992 tlab().make_parsable(true); // retire TLAB, if any
1993 }
1994
1995 #if INCLUDE_ALL_GCS
1996 if (UseG1GC) {
1997 flush_barrier_queues();
1998 }
1999 #endif // INCLUDE_ALL_GCS
2000
2001 Threads::remove(this);
2002 delete this;
2003 }
2004
2005
2006
2007
2008 JavaThread* JavaThread::active() {
2009 Thread* thread = Thread::current();
2010 if (thread->is_Java_thread()) {
2011 return (JavaThread*) thread;
2012 } else {
2013 assert(thread->is_VM_thread(), "this must be a vm thread");
2014 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2015 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2016 assert(ret->is_Java_thread(), "must be a Java thread");
2017 return ret;
2018 }
2019 }
2020
2021 bool JavaThread::is_lock_owned(address adr) const {
2022 if (Thread::is_lock_owned(adr)) return true;
2023
2024 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2025 if (chunk->contains(adr)) return true;
2026 }
2027
2028 return false;
2029 }
2030
2031
2032 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2033 chunk->set_next(monitor_chunks());
2034 set_monitor_chunks(chunk);
2035 }
2036
2037 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2038 guarantee(monitor_chunks() != NULL, "must be non empty");
2039 if (monitor_chunks() == chunk) {
2040 set_monitor_chunks(chunk->next());
2041 } else {
2042 MonitorChunk* prev = monitor_chunks();
2043 while (prev->next() != chunk) prev = prev->next();
2044 prev->set_next(chunk->next());
2045 }
2046 }
2047
2048 // JVM support.
2049
2050 // Note: this function shouldn't block if it's called in
2051 // _thread_in_native_trans state (such as from
2052 // check_special_condition_for_native_trans()).
2053 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2054
2055 if (has_last_Java_frame() && has_async_condition()) {
2056 // If we are at a polling page safepoint (not a poll return)
2057 // then we must defer async exception because live registers
2058 // will be clobbered by the exception path. Poll return is
2059 // ok because the call we a returning from already collides
2060 // with exception handling registers and so there is no issue.
2061 // (The exception handling path kills call result registers but
2062 // this is ok since the exception kills the result anyway).
2063
2064 if (is_at_poll_safepoint()) {
2065 // if the code we are returning to has deoptimized we must defer
2066 // the exception otherwise live registers get clobbered on the
2067 // exception path before deoptimization is able to retrieve them.
2068 //
2069 RegisterMap map(this, false);
2070 frame caller_fr = last_frame().sender(&map);
2071 assert(caller_fr.is_compiled_frame(), "what?");
2072 if (caller_fr.is_deoptimized_frame()) {
2073 log_info(exceptions)("deferred async exception at compiled safepoint");
2074 return;
2075 }
2076 }
2077 }
2078
2079 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2080 if (condition == _no_async_condition) {
2081 // Conditions have changed since has_special_runtime_exit_condition()
2082 // was called:
2083 // - if we were here only because of an external suspend request,
2084 // then that was taken care of above (or cancelled) so we are done
2085 // - if we were here because of another async request, then it has
2086 // been cleared between the has_special_runtime_exit_condition()
2087 // and now so again we are done
2088 return;
2089 }
2090
2091 // Check for pending async. exception
2092 if (_pending_async_exception != NULL) {
2093 // Only overwrite an already pending exception, if it is not a threadDeath.
2094 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2095
2096 // We cannot call Exceptions::_throw(...) here because we cannot block
2097 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2098
2099 if (log_is_enabled(Info, exceptions)) {
2100 ResourceMark rm;
2101 outputStream* logstream = Log(exceptions)::info_stream();
2102 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2103 if (has_last_Java_frame()) {
2104 frame f = last_frame();
2105 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2106 }
2107 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2108 }
2109 _pending_async_exception = NULL;
2110 clear_has_async_exception();
2111 }
2112 }
2113
2114 if (check_unsafe_error &&
2115 condition == _async_unsafe_access_error && !has_pending_exception()) {
2116 condition = _no_async_condition; // done
2117 switch (thread_state()) {
2118 case _thread_in_vm: {
2119 JavaThread* THREAD = this;
2120 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2121 }
2122 case _thread_in_native: {
2123 ThreadInVMfromNative tiv(this);
2124 JavaThread* THREAD = this;
2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2126 }
2127 case _thread_in_Java: {
2128 ThreadInVMfromJava tiv(this);
2129 JavaThread* THREAD = this;
2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2131 }
2132 default:
2133 ShouldNotReachHere();
2134 }
2135 }
2136
2137 assert(condition == _no_async_condition || has_pending_exception() ||
2138 (!check_unsafe_error && condition == _async_unsafe_access_error),
2139 "must have handled the async condition, if no exception");
2140 }
2141
2142 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2143 //
2144 // Check for pending external suspend. Internal suspend requests do
2145 // not use handle_special_runtime_exit_condition().
2146 // If JNIEnv proxies are allowed, don't self-suspend if the target
2147 // thread is not the current thread. In older versions of jdbx, jdbx
2148 // threads could call into the VM with another thread's JNIEnv so we
2149 // can be here operating on behalf of a suspended thread (4432884).
2150 bool do_self_suspend = is_external_suspend_with_lock();
2151 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2152 //
2153 // Because thread is external suspended the safepoint code will count
2154 // thread as at a safepoint. This can be odd because we can be here
2155 // as _thread_in_Java which would normally transition to _thread_blocked
2156 // at a safepoint. We would like to mark the thread as _thread_blocked
2157 // before calling java_suspend_self like all other callers of it but
2158 // we must then observe proper safepoint protocol. (We can't leave
2159 // _thread_blocked with a safepoint in progress). However we can be
2160 // here as _thread_in_native_trans so we can't use a normal transition
2161 // constructor/destructor pair because they assert on that type of
2162 // transition. We could do something like:
2163 //
2164 // JavaThreadState state = thread_state();
2165 // set_thread_state(_thread_in_vm);
2166 // {
2167 // ThreadBlockInVM tbivm(this);
2168 // java_suspend_self()
2169 // }
2170 // set_thread_state(_thread_in_vm_trans);
2171 // if (safepoint) block;
2172 // set_thread_state(state);
2173 //
2174 // but that is pretty messy. Instead we just go with the way the
2175 // code has worked before and note that this is the only path to
2176 // java_suspend_self that doesn't put the thread in _thread_blocked
2177 // mode.
2178
2179 frame_anchor()->make_walkable(this);
2180 java_suspend_self();
2181
2182 // We might be here for reasons in addition to the self-suspend request
2183 // so check for other async requests.
2184 }
2185
2186 if (check_asyncs) {
2187 check_and_handle_async_exceptions();
2188 }
2189 }
2190
2191 void JavaThread::send_thread_stop(oop java_throwable) {
2192 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2193 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2194 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2195
2196 // Do not throw asynchronous exceptions against the compiler thread
2197 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2198 if (!can_call_java()) return;
2199
2200 {
2201 // Actually throw the Throwable against the target Thread - however
2202 // only if there is no thread death exception installed already.
2203 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2204 // If the topmost frame is a runtime stub, then we are calling into
2205 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2206 // must deoptimize the caller before continuing, as the compiled exception handler table
2207 // may not be valid
2208 if (has_last_Java_frame()) {
2209 frame f = last_frame();
2210 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2211 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2212 RegisterMap reg_map(this, UseBiasedLocking);
2213 frame compiled_frame = f.sender(®_map);
2214 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2215 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2216 }
2217 }
2218 }
2219
2220 // Set async. pending exception in thread.
2221 set_pending_async_exception(java_throwable);
2222
2223 if (log_is_enabled(Info, exceptions)) {
2224 ResourceMark rm;
2225 log_info(exceptions)("Pending Async. exception installed of type: %s",
2226 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2227 }
2228 // for AbortVMOnException flag
2229 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2230 }
2231 }
2232
2233
2234 // Interrupt thread so it will wake up from a potential wait()
2235 Thread::interrupt(this);
2236 }
2237
2238 // External suspension mechanism.
2239 //
2240 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2241 // to any VM_locks and it is at a transition
2242 // Self-suspension will happen on the transition out of the vm.
2243 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2244 //
2245 // Guarantees on return:
2246 // + Target thread will not execute any new bytecode (that's why we need to
2247 // force a safepoint)
2248 // + Target thread will not enter any new monitors
2249 //
2250 void JavaThread::java_suspend() {
2251 { MutexLocker mu(Threads_lock);
2252 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2253 return;
2254 }
2255 }
2256
2257 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2258 if (!is_external_suspend()) {
2259 // a racing resume has cancelled us; bail out now
2260 return;
2261 }
2262
2263 // suspend is done
2264 uint32_t debug_bits = 0;
2265 // Warning: is_ext_suspend_completed() may temporarily drop the
2266 // SR_lock to allow the thread to reach a stable thread state if
2267 // it is currently in a transient thread state.
2268 if (is_ext_suspend_completed(false /* !called_by_wait */,
2269 SuspendRetryDelay, &debug_bits)) {
2270 return;
2271 }
2272 }
2273
2274 VM_ForceSafepoint vm_suspend;
2275 VMThread::execute(&vm_suspend);
2276 }
2277
2278 // Part II of external suspension.
2279 // A JavaThread self suspends when it detects a pending external suspend
2280 // request. This is usually on transitions. It is also done in places
2281 // where continuing to the next transition would surprise the caller,
2282 // e.g., monitor entry.
2283 //
2284 // Returns the number of times that the thread self-suspended.
2285 //
2286 // Note: DO NOT call java_suspend_self() when you just want to block current
2287 // thread. java_suspend_self() is the second stage of cooperative
2288 // suspension for external suspend requests and should only be used
2289 // to complete an external suspend request.
2290 //
2291 int JavaThread::java_suspend_self() {
2292 int ret = 0;
2293
2294 // we are in the process of exiting so don't suspend
2295 if (is_exiting()) {
2296 clear_external_suspend();
2297 return ret;
2298 }
2299
2300 assert(_anchor.walkable() ||
2301 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2302 "must have walkable stack");
2303
2304 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2305
2306 assert(!this->is_ext_suspended(),
2307 "a thread trying to self-suspend should not already be suspended");
2308
2309 if (this->is_suspend_equivalent()) {
2310 // If we are self-suspending as a result of the lifting of a
2311 // suspend equivalent condition, then the suspend_equivalent
2312 // flag is not cleared until we set the ext_suspended flag so
2313 // that wait_for_ext_suspend_completion() returns consistent
2314 // results.
2315 this->clear_suspend_equivalent();
2316 }
2317
2318 // A racing resume may have cancelled us before we grabbed SR_lock
2319 // above. Or another external suspend request could be waiting for us
2320 // by the time we return from SR_lock()->wait(). The thread
2321 // that requested the suspension may already be trying to walk our
2322 // stack and if we return now, we can change the stack out from under
2323 // it. This would be a "bad thing (TM)" and cause the stack walker
2324 // to crash. We stay self-suspended until there are no more pending
2325 // external suspend requests.
2326 while (is_external_suspend()) {
2327 ret++;
2328 this->set_ext_suspended();
2329
2330 // _ext_suspended flag is cleared by java_resume()
2331 while (is_ext_suspended()) {
2332 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2333 }
2334 }
2335
2336 return ret;
2337 }
2338
2339 #ifdef ASSERT
2340 // verify the JavaThread has not yet been published in the Threads::list, and
2341 // hence doesn't need protection from concurrent access at this stage
2342 void JavaThread::verify_not_published() {
2343 if (!Threads_lock->owned_by_self()) {
2344 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2345 assert(!Threads::includes(this),
2346 "java thread shouldn't have been published yet!");
2347 } else {
2348 assert(!Threads::includes(this),
2349 "java thread shouldn't have been published yet!");
2350 }
2351 }
2352 #endif
2353
2354 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2355 // progress or when _suspend_flags is non-zero.
2356 // Current thread needs to self-suspend if there is a suspend request and/or
2357 // block if a safepoint is in progress.
2358 // Async exception ISN'T checked.
2359 // Note only the ThreadInVMfromNative transition can call this function
2360 // directly and when thread state is _thread_in_native_trans
2361 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2362 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2363
2364 JavaThread *curJT = JavaThread::current();
2365 bool do_self_suspend = thread->is_external_suspend();
2366
2367 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2368
2369 // If JNIEnv proxies are allowed, don't self-suspend if the target
2370 // thread is not the current thread. In older versions of jdbx, jdbx
2371 // threads could call into the VM with another thread's JNIEnv so we
2372 // can be here operating on behalf of a suspended thread (4432884).
2373 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2374 JavaThreadState state = thread->thread_state();
2375
2376 // We mark this thread_blocked state as a suspend-equivalent so
2377 // that a caller to is_ext_suspend_completed() won't be confused.
2378 // The suspend-equivalent state is cleared by java_suspend_self().
2379 thread->set_suspend_equivalent();
2380
2381 // If the safepoint code sees the _thread_in_native_trans state, it will
2382 // wait until the thread changes to other thread state. There is no
2383 // guarantee on how soon we can obtain the SR_lock and complete the
2384 // self-suspend request. It would be a bad idea to let safepoint wait for
2385 // too long. Temporarily change the state to _thread_blocked to
2386 // let the VM thread know that this thread is ready for GC. The problem
2387 // of changing thread state is that safepoint could happen just after
2388 // java_suspend_self() returns after being resumed, and VM thread will
2389 // see the _thread_blocked state. We must check for safepoint
2390 // after restoring the state and make sure we won't leave while a safepoint
2391 // is in progress.
2392 thread->set_thread_state(_thread_blocked);
2393 thread->java_suspend_self();
2394 thread->set_thread_state(state);
2395 // Make sure new state is seen by VM thread
2396 if (os::is_MP()) {
2397 if (UseMembar) {
2398 // Force a fence between the write above and read below
2399 OrderAccess::fence();
2400 } else {
2401 // Must use this rather than serialization page in particular on Windows
2402 InterfaceSupport::serialize_memory(thread);
2403 }
2404 }
2405 }
2406
2407 if (SafepointSynchronize::do_call_back()) {
2408 // If we are safepointing, then block the caller which may not be
2409 // the same as the target thread (see above).
2410 SafepointSynchronize::block(curJT);
2411 }
2412
2413 if (thread->is_deopt_suspend()) {
2414 thread->clear_deopt_suspend();
2415 RegisterMap map(thread, false);
2416 frame f = thread->last_frame();
2417 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2418 f = f.sender(&map);
2419 }
2420 if (f.id() == thread->must_deopt_id()) {
2421 thread->clear_must_deopt_id();
2422 f.deoptimize(thread);
2423 } else {
2424 fatal("missed deoptimization!");
2425 }
2426 }
2427 }
2428
2429 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2430 // progress or when _suspend_flags is non-zero.
2431 // Current thread needs to self-suspend if there is a suspend request and/or
2432 // block if a safepoint is in progress.
2433 // Also check for pending async exception (not including unsafe access error).
2434 // Note only the native==>VM/Java barriers can call this function and when
2435 // thread state is _thread_in_native_trans.
2436 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2437 check_safepoint_and_suspend_for_native_trans(thread);
2438
2439 if (thread->has_async_exception()) {
2440 // We are in _thread_in_native_trans state, don't handle unsafe
2441 // access error since that may block.
2442 thread->check_and_handle_async_exceptions(false);
2443 }
2444 }
2445
2446 // This is a variant of the normal
2447 // check_special_condition_for_native_trans with slightly different
2448 // semantics for use by critical native wrappers. It does all the
2449 // normal checks but also performs the transition back into
2450 // thread_in_Java state. This is required so that critical natives
2451 // can potentially block and perform a GC if they are the last thread
2452 // exiting the GCLocker.
2453 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2454 check_special_condition_for_native_trans(thread);
2455
2456 // Finish the transition
2457 thread->set_thread_state(_thread_in_Java);
2458
2459 if (thread->do_critical_native_unlock()) {
2460 ThreadInVMfromJavaNoAsyncException tiv(thread);
2461 GCLocker::unlock_critical(thread);
2462 thread->clear_critical_native_unlock();
2463 }
2464 }
2465
2466 // We need to guarantee the Threads_lock here, since resumes are not
2467 // allowed during safepoint synchronization
2468 // Can only resume from an external suspension
2469 void JavaThread::java_resume() {
2470 assert_locked_or_safepoint(Threads_lock);
2471
2472 // Sanity check: thread is gone, has started exiting or the thread
2473 // was not externally suspended.
2474 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2475 return;
2476 }
2477
2478 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2479
2480 clear_external_suspend();
2481
2482 if (is_ext_suspended()) {
2483 clear_ext_suspended();
2484 SR_lock()->notify_all();
2485 }
2486 }
2487
2488 size_t JavaThread::_stack_red_zone_size = 0;
2489 size_t JavaThread::_stack_yellow_zone_size = 0;
2490 size_t JavaThread::_stack_reserved_zone_size = 0;
2491 size_t JavaThread::_stack_shadow_zone_size = 0;
2492
2493 void JavaThread::create_stack_guard_pages() {
2494 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2495 address low_addr = stack_end();
2496 size_t len = stack_guard_zone_size();
2497
2498 int must_commit = os::must_commit_stack_guard_pages();
2499 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2500
2501 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2502 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2503 return;
2504 }
2505
2506 if (os::guard_memory((char *) low_addr, len)) {
2507 _stack_guard_state = stack_guard_enabled;
2508 } else {
2509 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2510 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2511 if (os::uncommit_memory((char *) low_addr, len)) {
2512 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2513 }
2514 return;
2515 }
2516
2517 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2518 PTR_FORMAT "-" PTR_FORMAT ".",
2519 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2520 }
2521
2522 void JavaThread::remove_stack_guard_pages() {
2523 assert(Thread::current() == this, "from different thread");
2524 if (_stack_guard_state == stack_guard_unused) return;
2525 address low_addr = stack_end();
2526 size_t len = stack_guard_zone_size();
2527
2528 if (os::must_commit_stack_guard_pages()) {
2529 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2530 _stack_guard_state = stack_guard_unused;
2531 } else {
2532 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2533 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2534 return;
2535 }
2536 } else {
2537 if (_stack_guard_state == stack_guard_unused) return;
2538 if (os::unguard_memory((char *) low_addr, len)) {
2539 _stack_guard_state = stack_guard_unused;
2540 } else {
2541 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2542 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2543 return;
2544 }
2545 }
2546
2547 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2548 PTR_FORMAT "-" PTR_FORMAT ".",
2549 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2550 }
2551
2552 void JavaThread::enable_stack_reserved_zone() {
2553 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2554 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2555
2556 // The base notation is from the stack's point of view, growing downward.
2557 // We need to adjust it to work correctly with guard_memory()
2558 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2559
2560 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2561 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2562
2563 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2564 _stack_guard_state = stack_guard_enabled;
2565 } else {
2566 warning("Attempt to guard stack reserved zone failed.");
2567 }
2568 enable_register_stack_guard();
2569 }
2570
2571 void JavaThread::disable_stack_reserved_zone() {
2572 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2573 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2574
2575 // Simply return if called for a thread that does not use guard pages.
2576 if (_stack_guard_state == stack_guard_unused) return;
2577
2578 // The base notation is from the stack's point of view, growing downward.
2579 // We need to adjust it to work correctly with guard_memory()
2580 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2581
2582 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2583 _stack_guard_state = stack_guard_reserved_disabled;
2584 } else {
2585 warning("Attempt to unguard stack reserved zone failed.");
2586 }
2587 disable_register_stack_guard();
2588 }
2589
2590 void JavaThread::enable_stack_yellow_reserved_zone() {
2591 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2592 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2593
2594 // The base notation is from the stacks point of view, growing downward.
2595 // We need to adjust it to work correctly with guard_memory()
2596 address base = stack_red_zone_base();
2597
2598 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2599 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2600
2601 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2602 _stack_guard_state = stack_guard_enabled;
2603 } else {
2604 warning("Attempt to guard stack yellow zone failed.");
2605 }
2606 enable_register_stack_guard();
2607 }
2608
2609 void JavaThread::disable_stack_yellow_reserved_zone() {
2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2611 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2612
2613 // Simply return if called for a thread that does not use guard pages.
2614 if (_stack_guard_state == stack_guard_unused) return;
2615
2616 // The base notation is from the stacks point of view, growing downward.
2617 // We need to adjust it to work correctly with guard_memory()
2618 address base = stack_red_zone_base();
2619
2620 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2621 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2622 } else {
2623 warning("Attempt to unguard stack yellow zone failed.");
2624 }
2625 disable_register_stack_guard();
2626 }
2627
2628 void JavaThread::enable_stack_red_zone() {
2629 // The base notation is from the stacks point of view, growing downward.
2630 // We need to adjust it to work correctly with guard_memory()
2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2632 address base = stack_red_zone_base() - stack_red_zone_size();
2633
2634 guarantee(base < stack_base(), "Error calculating stack red zone");
2635 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2636
2637 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2638 warning("Attempt to guard stack red zone failed.");
2639 }
2640 }
2641
2642 void JavaThread::disable_stack_red_zone() {
2643 // The base notation is from the stacks point of view, growing downward.
2644 // We need to adjust it to work correctly with guard_memory()
2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2646 address base = stack_red_zone_base() - stack_red_zone_size();
2647 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2648 warning("Attempt to unguard stack red zone failed.");
2649 }
2650 }
2651
2652 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2653 // ignore is there is no stack
2654 if (!has_last_Java_frame()) return;
2655 // traverse the stack frames. Starts from top frame.
2656 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2657 frame* fr = fst.current();
2658 f(fr, fst.register_map());
2659 }
2660 }
2661
2662
2663 #ifndef PRODUCT
2664 // Deoptimization
2665 // Function for testing deoptimization
2666 void JavaThread::deoptimize() {
2667 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2668 StackFrameStream fst(this, UseBiasedLocking);
2669 bool deopt = false; // Dump stack only if a deopt actually happens.
2670 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2671 // Iterate over all frames in the thread and deoptimize
2672 for (; !fst.is_done(); fst.next()) {
2673 if (fst.current()->can_be_deoptimized()) {
2674
2675 if (only_at) {
2676 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2677 // consists of comma or carriage return separated numbers so
2678 // search for the current bci in that string.
2679 address pc = fst.current()->pc();
2680 nmethod* nm = (nmethod*) fst.current()->cb();
2681 ScopeDesc* sd = nm->scope_desc_at(pc);
2682 char buffer[8];
2683 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2684 size_t len = strlen(buffer);
2685 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2686 while (found != NULL) {
2687 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2688 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2689 // Check that the bci found is bracketed by terminators.
2690 break;
2691 }
2692 found = strstr(found + 1, buffer);
2693 }
2694 if (!found) {
2695 continue;
2696 }
2697 }
2698
2699 if (DebugDeoptimization && !deopt) {
2700 deopt = true; // One-time only print before deopt
2701 tty->print_cr("[BEFORE Deoptimization]");
2702 trace_frames();
2703 trace_stack();
2704 }
2705 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2706 }
2707 }
2708
2709 if (DebugDeoptimization && deopt) {
2710 tty->print_cr("[AFTER Deoptimization]");
2711 trace_frames();
2712 }
2713 }
2714
2715
2716 // Make zombies
2717 void JavaThread::make_zombies() {
2718 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2719 if (fst.current()->can_be_deoptimized()) {
2720 // it is a Java nmethod
2721 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2722 nm->make_not_entrant();
2723 }
2724 }
2725 }
2726 #endif // PRODUCT
2727
2728
2729 void JavaThread::deoptimized_wrt_marked_nmethods() {
2730 if (!has_last_Java_frame()) return;
2731 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2732 StackFrameStream fst(this, UseBiasedLocking);
2733 for (; !fst.is_done(); fst.next()) {
2734 if (fst.current()->should_be_deoptimized()) {
2735 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2736 }
2737 }
2738 }
2739
2740
2741 // If the caller is a NamedThread, then remember, in the current scope,
2742 // the given JavaThread in its _processed_thread field.
2743 class RememberProcessedThread: public StackObj {
2744 NamedThread* _cur_thr;
2745 public:
2746 RememberProcessedThread(JavaThread* jthr) {
2747 Thread* thread = Thread::current();
2748 if (thread->is_Named_thread()) {
2749 _cur_thr = (NamedThread *)thread;
2750 _cur_thr->set_processed_thread(jthr);
2751 } else {
2752 _cur_thr = NULL;
2753 }
2754 }
2755
2756 ~RememberProcessedThread() {
2757 if (_cur_thr) {
2758 _cur_thr->set_processed_thread(NULL);
2759 }
2760 }
2761 };
2762
2763 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2764 // Verify that the deferred card marks have been flushed.
2765 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2766
2767 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2768 // since there may be more than one thread using each ThreadProfiler.
2769
2770 // Traverse the GCHandles
2771 Thread::oops_do(f, cf);
2772
2773 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2774
2775 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2776 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2777
2778 if (has_last_Java_frame()) {
2779 // Record JavaThread to GC thread
2780 RememberProcessedThread rpt(this);
2781
2782 // Traverse the privileged stack
2783 if (_privileged_stack_top != NULL) {
2784 _privileged_stack_top->oops_do(f);
2785 }
2786
2787 // traverse the registered growable array
2788 if (_array_for_gc != NULL) {
2789 for (int index = 0; index < _array_for_gc->length(); index++) {
2790 f->do_oop(_array_for_gc->adr_at(index));
2791 }
2792 }
2793
2794 // Traverse the monitor chunks
2795 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2796 chunk->oops_do(f);
2797 }
2798
2799 // Traverse the execution stack
2800 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2801 fst.current()->oops_do(f, cf, fst.register_map());
2802 }
2803 }
2804
2805 // callee_target is never live across a gc point so NULL it here should
2806 // it still contain a methdOop.
2807
2808 set_callee_target(NULL);
2809
2810 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2811 // If we have deferred set_locals there might be oops waiting to be
2812 // written
2813 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2814 if (list != NULL) {
2815 for (int i = 0; i < list->length(); i++) {
2816 list->at(i)->oops_do(f);
2817 }
2818 }
2819
2820 // Traverse instance variables at the end since the GC may be moving things
2821 // around using this function
2822 f->do_oop((oop*) &_threadObj);
2823 f->do_oop((oop*) &_vm_result);
2824 f->do_oop((oop*) &_exception_oop);
2825 f->do_oop((oop*) &_pending_async_exception);
2826
2827 if (jvmti_thread_state() != NULL) {
2828 jvmti_thread_state()->oops_do(f);
2829 }
2830 }
2831
2832 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2833 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2834 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2835
2836 if (has_last_Java_frame()) {
2837 // Traverse the execution stack
2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2839 fst.current()->nmethods_do(cf);
2840 }
2841 }
2842 }
2843
2844 void JavaThread::metadata_do(void f(Metadata*)) {
2845 if (has_last_Java_frame()) {
2846 // Traverse the execution stack to call f() on the methods in the stack
2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848 fst.current()->metadata_do(f);
2849 }
2850 } else if (is_Compiler_thread()) {
2851 // need to walk ciMetadata in current compile tasks to keep alive.
2852 CompilerThread* ct = (CompilerThread*)this;
2853 if (ct->env() != NULL) {
2854 ct->env()->metadata_do(f);
2855 }
2856 if (ct->task() != NULL) {
2857 ct->task()->metadata_do(f);
2858 }
2859 }
2860 }
2861
2862 // Printing
2863 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2864 switch (_thread_state) {
2865 case _thread_uninitialized: return "_thread_uninitialized";
2866 case _thread_new: return "_thread_new";
2867 case _thread_new_trans: return "_thread_new_trans";
2868 case _thread_in_native: return "_thread_in_native";
2869 case _thread_in_native_trans: return "_thread_in_native_trans";
2870 case _thread_in_vm: return "_thread_in_vm";
2871 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2872 case _thread_in_Java: return "_thread_in_Java";
2873 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2874 case _thread_blocked: return "_thread_blocked";
2875 case _thread_blocked_trans: return "_thread_blocked_trans";
2876 default: return "unknown thread state";
2877 }
2878 }
2879
2880 #ifndef PRODUCT
2881 void JavaThread::print_thread_state_on(outputStream *st) const {
2882 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2883 };
2884 void JavaThread::print_thread_state() const {
2885 print_thread_state_on(tty);
2886 }
2887 #endif // PRODUCT
2888
2889 // Called by Threads::print() for VM_PrintThreads operation
2890 void JavaThread::print_on(outputStream *st) const {
2891 st->print_raw("\"");
2892 st->print_raw(get_thread_name());
2893 st->print_raw("\" ");
2894 oop thread_oop = threadObj();
2895 if (thread_oop != NULL) {
2896 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2897 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2898 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2899 }
2900 Thread::print_on(st);
2901 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2902 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2903 if (thread_oop != NULL) {
2904 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2905 }
2906 #ifndef PRODUCT
2907 print_thread_state_on(st);
2908 _safepoint_state->print_on(st);
2909 #endif // PRODUCT
2910 if (is_Compiler_thread()) {
2911 CompilerThread* ct = (CompilerThread*)this;
2912 if (ct->task() != NULL) {
2913 st->print(" Compiling: ");
2914 ct->task()->print(st, NULL, true, false);
2915 } else {
2916 st->print(" No compile task");
2917 }
2918 st->cr();
2919 }
2920 }
2921
2922 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2923 st->print("%s", get_thread_name_string(buf, buflen));
2924 }
2925
2926 // Called by fatal error handler. The difference between this and
2927 // JavaThread::print() is that we can't grab lock or allocate memory.
2928 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2929 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2930 oop thread_obj = threadObj();
2931 if (thread_obj != NULL) {
2932 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2933 }
2934 st->print(" [");
2935 st->print("%s", _get_thread_state_name(_thread_state));
2936 if (osthread()) {
2937 st->print(", id=%d", osthread()->thread_id());
2938 }
2939 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2940 p2i(stack_end()), p2i(stack_base()));
2941 st->print("]");
2942 return;
2943 }
2944
2945 // Verification
2946
2947 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2948
2949 void JavaThread::verify() {
2950 // Verify oops in the thread.
2951 oops_do(&VerifyOopClosure::verify_oop, NULL);
2952
2953 // Verify the stack frames.
2954 frames_do(frame_verify);
2955 }
2956
2957 // CR 6300358 (sub-CR 2137150)
2958 // Most callers of this method assume that it can't return NULL but a
2959 // thread may not have a name whilst it is in the process of attaching to
2960 // the VM - see CR 6412693, and there are places where a JavaThread can be
2961 // seen prior to having it's threadObj set (eg JNI attaching threads and
2962 // if vm exit occurs during initialization). These cases can all be accounted
2963 // for such that this method never returns NULL.
2964 const char* JavaThread::get_thread_name() const {
2965 #ifdef ASSERT
2966 // early safepoints can hit while current thread does not yet have TLS
2967 if (!SafepointSynchronize::is_at_safepoint()) {
2968 Thread *cur = Thread::current();
2969 if (!(cur->is_Java_thread() && cur == this)) {
2970 // Current JavaThreads are allowed to get their own name without
2971 // the Threads_lock.
2972 assert_locked_or_safepoint(Threads_lock);
2973 }
2974 }
2975 #endif // ASSERT
2976 return get_thread_name_string();
2977 }
2978
2979 // Returns a non-NULL representation of this thread's name, or a suitable
2980 // descriptive string if there is no set name
2981 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2982 const char* name_str;
2983 oop thread_obj = threadObj();
2984 if (thread_obj != NULL) {
2985 oop name = java_lang_Thread::name(thread_obj);
2986 if (name != NULL) {
2987 if (buf == NULL) {
2988 name_str = java_lang_String::as_utf8_string(name);
2989 } else {
2990 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2991 }
2992 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2993 name_str = "<no-name - thread is attaching>";
2994 } else {
2995 name_str = Thread::name();
2996 }
2997 } else {
2998 name_str = Thread::name();
2999 }
3000 assert(name_str != NULL, "unexpected NULL thread name");
3001 return name_str;
3002 }
3003
3004
3005 const char* JavaThread::get_threadgroup_name() const {
3006 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3007 oop thread_obj = threadObj();
3008 if (thread_obj != NULL) {
3009 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3010 if (thread_group != NULL) {
3011 // ThreadGroup.name can be null
3012 return java_lang_ThreadGroup::name(thread_group);
3013 }
3014 }
3015 return NULL;
3016 }
3017
3018 const char* JavaThread::get_parent_name() const {
3019 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3020 oop thread_obj = threadObj();
3021 if (thread_obj != NULL) {
3022 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3023 if (thread_group != NULL) {
3024 oop parent = java_lang_ThreadGroup::parent(thread_group);
3025 if (parent != NULL) {
3026 // ThreadGroup.name can be null
3027 return java_lang_ThreadGroup::name(parent);
3028 }
3029 }
3030 }
3031 return NULL;
3032 }
3033
3034 ThreadPriority JavaThread::java_priority() const {
3035 oop thr_oop = threadObj();
3036 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3037 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3038 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3039 return priority;
3040 }
3041
3042 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3043
3044 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3045 // Link Java Thread object <-> C++ Thread
3046
3047 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3048 // and put it into a new Handle. The Handle "thread_oop" can then
3049 // be used to pass the C++ thread object to other methods.
3050
3051 // Set the Java level thread object (jthread) field of the
3052 // new thread (a JavaThread *) to C++ thread object using the
3053 // "thread_oop" handle.
3054
3055 // Set the thread field (a JavaThread *) of the
3056 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3057
3058 Handle thread_oop(Thread::current(),
3059 JNIHandles::resolve_non_null(jni_thread));
3060 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3061 "must be initialized");
3062 set_threadObj(thread_oop());
3063 java_lang_Thread::set_thread(thread_oop(), this);
3064
3065 if (prio == NoPriority) {
3066 prio = java_lang_Thread::priority(thread_oop());
3067 assert(prio != NoPriority, "A valid priority should be present");
3068 }
3069
3070 // Push the Java priority down to the native thread; needs Threads_lock
3071 Thread::set_priority(this, prio);
3072
3073 prepare_ext();
3074
3075 // Add the new thread to the Threads list and set it in motion.
3076 // We must have threads lock in order to call Threads::add.
3077 // It is crucial that we do not block before the thread is
3078 // added to the Threads list for if a GC happens, then the java_thread oop
3079 // will not be visited by GC.
3080 Threads::add(this);
3081 }
3082
3083 oop JavaThread::current_park_blocker() {
3084 // Support for JSR-166 locks
3085 oop thread_oop = threadObj();
3086 if (thread_oop != NULL &&
3087 JDK_Version::current().supports_thread_park_blocker()) {
3088 return java_lang_Thread::park_blocker(thread_oop);
3089 }
3090 return NULL;
3091 }
3092
3093
3094 void JavaThread::print_stack_on(outputStream* st) {
3095 if (!has_last_Java_frame()) return;
3096 ResourceMark rm;
3097 HandleMark hm;
3098
3099 RegisterMap reg_map(this);
3100 vframe* start_vf = last_java_vframe(®_map);
3101 int count = 0;
3102 for (vframe* f = start_vf; f; f = f->sender()) {
3103 if (f->is_java_frame()) {
3104 javaVFrame* jvf = javaVFrame::cast(f);
3105 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3106
3107 // Print out lock information
3108 if (JavaMonitorsInStackTrace) {
3109 jvf->print_lock_info_on(st, count);
3110 }
3111 } else {
3112 // Ignore non-Java frames
3113 }
3114
3115 // Bail-out case for too deep stacks
3116 count++;
3117 if (MaxJavaStackTraceDepth == count) return;
3118 }
3119 }
3120
3121
3122 // JVMTI PopFrame support
3123 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3124 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3125 if (in_bytes(size_in_bytes) != 0) {
3126 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3127 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3128 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3129 }
3130 }
3131
3132 void* JavaThread::popframe_preserved_args() {
3133 return _popframe_preserved_args;
3134 }
3135
3136 ByteSize JavaThread::popframe_preserved_args_size() {
3137 return in_ByteSize(_popframe_preserved_args_size);
3138 }
3139
3140 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3141 int sz = in_bytes(popframe_preserved_args_size());
3142 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3143 return in_WordSize(sz / wordSize);
3144 }
3145
3146 void JavaThread::popframe_free_preserved_args() {
3147 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3148 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3149 _popframe_preserved_args = NULL;
3150 _popframe_preserved_args_size = 0;
3151 }
3152
3153 #ifndef PRODUCT
3154
3155 void JavaThread::trace_frames() {
3156 tty->print_cr("[Describe stack]");
3157 int frame_no = 1;
3158 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3159 tty->print(" %d. ", frame_no++);
3160 fst.current()->print_value_on(tty, this);
3161 tty->cr();
3162 }
3163 }
3164
3165 class PrintAndVerifyOopClosure: public OopClosure {
3166 protected:
3167 template <class T> inline void do_oop_work(T* p) {
3168 oop obj = oopDesc::load_decode_heap_oop(p);
3169 if (obj == NULL) return;
3170 tty->print(INTPTR_FORMAT ": ", p2i(p));
3171 if (obj->is_oop_or_null()) {
3172 if (obj->is_objArray()) {
3173 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3174 } else {
3175 obj->print();
3176 }
3177 } else {
3178 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3179 }
3180 tty->cr();
3181 }
3182 public:
3183 virtual void do_oop(oop* p) { do_oop_work(p); }
3184 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3185 };
3186
3187
3188 static void oops_print(frame* f, const RegisterMap *map) {
3189 PrintAndVerifyOopClosure print;
3190 f->print_value();
3191 f->oops_do(&print, NULL, (RegisterMap*)map);
3192 }
3193
3194 // Print our all the locations that contain oops and whether they are
3195 // valid or not. This useful when trying to find the oldest frame
3196 // where an oop has gone bad since the frame walk is from youngest to
3197 // oldest.
3198 void JavaThread::trace_oops() {
3199 tty->print_cr("[Trace oops]");
3200 frames_do(oops_print);
3201 }
3202
3203
3204 #ifdef ASSERT
3205 // Print or validate the layout of stack frames
3206 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3207 ResourceMark rm;
3208 PRESERVE_EXCEPTION_MARK;
3209 FrameValues values;
3210 int frame_no = 0;
3211 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3212 fst.current()->describe(values, ++frame_no);
3213 if (depth == frame_no) break;
3214 }
3215 if (validate_only) {
3216 values.validate();
3217 } else {
3218 tty->print_cr("[Describe stack layout]");
3219 values.print(this);
3220 }
3221 }
3222 #endif
3223
3224 void JavaThread::trace_stack_from(vframe* start_vf) {
3225 ResourceMark rm;
3226 int vframe_no = 1;
3227 for (vframe* f = start_vf; f; f = f->sender()) {
3228 if (f->is_java_frame()) {
3229 javaVFrame::cast(f)->print_activation(vframe_no++);
3230 } else {
3231 f->print();
3232 }
3233 if (vframe_no > StackPrintLimit) {
3234 tty->print_cr("...<more frames>...");
3235 return;
3236 }
3237 }
3238 }
3239
3240
3241 void JavaThread::trace_stack() {
3242 if (!has_last_Java_frame()) return;
3243 ResourceMark rm;
3244 HandleMark hm;
3245 RegisterMap reg_map(this);
3246 trace_stack_from(last_java_vframe(®_map));
3247 }
3248
3249
3250 #endif // PRODUCT
3251
3252
3253 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3254 assert(reg_map != NULL, "a map must be given");
3255 frame f = last_frame();
3256 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3257 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3258 }
3259 return NULL;
3260 }
3261
3262
3263 Klass* JavaThread::security_get_caller_class(int depth) {
3264 vframeStream vfst(this);
3265 vfst.security_get_caller_frame(depth);
3266 if (!vfst.at_end()) {
3267 return vfst.method()->method_holder();
3268 }
3269 return NULL;
3270 }
3271
3272 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3273 assert(thread->is_Compiler_thread(), "must be compiler thread");
3274 CompileBroker::compiler_thread_loop();
3275 }
3276
3277 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3278 NMethodSweeper::sweeper_loop();
3279 }
3280
3281 // Create a CompilerThread
3282 CompilerThread::CompilerThread(CompileQueue* queue,
3283 CompilerCounters* counters)
3284 : JavaThread(&compiler_thread_entry) {
3285 _env = NULL;
3286 _log = NULL;
3287 _task = NULL;
3288 _queue = queue;
3289 _counters = counters;
3290 _buffer_blob = NULL;
3291 _compiler = NULL;
3292
3293 #ifndef PRODUCT
3294 _ideal_graph_printer = NULL;
3295 #endif
3296 }
3297
3298 bool CompilerThread::can_call_java() const {
3299 return _compiler != NULL && _compiler->is_jvmci();
3300 }
3301
3302 // Create sweeper thread
3303 CodeCacheSweeperThread::CodeCacheSweeperThread()
3304 : JavaThread(&sweeper_thread_entry) {
3305 _scanned_compiled_method = NULL;
3306 }
3307
3308 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3309 JavaThread::oops_do(f, cf);
3310 if (_scanned_compiled_method != NULL && cf != NULL) {
3311 // Safepoints can occur when the sweeper is scanning an nmethod so
3312 // process it here to make sure it isn't unloaded in the middle of
3313 // a scan.
3314 cf->do_code_blob(_scanned_compiled_method);
3315 }
3316 }
3317
3318 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3319 JavaThread::nmethods_do(cf);
3320 if (_scanned_compiled_method != NULL && cf != NULL) {
3321 // Safepoints can occur when the sweeper is scanning an nmethod so
3322 // process it here to make sure it isn't unloaded in the middle of
3323 // a scan.
3324 cf->do_code_blob(_scanned_compiled_method);
3325 }
3326 }
3327
3328
3329 // ======= Threads ========
3330
3331 // The Threads class links together all active threads, and provides
3332 // operations over all threads. It is protected by its own Mutex
3333 // lock, which is also used in other contexts to protect thread
3334 // operations from having the thread being operated on from exiting
3335 // and going away unexpectedly (e.g., safepoint synchronization)
3336
3337 JavaThread* Threads::_thread_list = NULL;
3338 int Threads::_number_of_threads = 0;
3339 int Threads::_number_of_non_daemon_threads = 0;
3340 int Threads::_return_code = 0;
3341 int Threads::_thread_claim_parity = 0;
3342 size_t JavaThread::_stack_size_at_create = 0;
3343 #ifdef ASSERT
3344 bool Threads::_vm_complete = false;
3345 #endif
3346
3347 // All JavaThreads
3348 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3349
3350 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3351 void Threads::threads_do(ThreadClosure* tc) {
3352 assert_locked_or_safepoint(Threads_lock);
3353 // ALL_JAVA_THREADS iterates through all JavaThreads
3354 ALL_JAVA_THREADS(p) {
3355 tc->do_thread(p);
3356 }
3357 // Someday we could have a table or list of all non-JavaThreads.
3358 // For now, just manually iterate through them.
3359 tc->do_thread(VMThread::vm_thread());
3360 Universe::heap()->gc_threads_do(tc);
3361 WatcherThread *wt = WatcherThread::watcher_thread();
3362 // Strictly speaking, the following NULL check isn't sufficient to make sure
3363 // the data for WatcherThread is still valid upon being examined. However,
3364 // considering that WatchThread terminates when the VM is on the way to
3365 // exit at safepoint, the chance of the above is extremely small. The right
3366 // way to prevent termination of WatcherThread would be to acquire
3367 // Terminator_lock, but we can't do that without violating the lock rank
3368 // checking in some cases.
3369 if (wt != NULL) {
3370 tc->do_thread(wt);
3371 }
3372
3373 // If CompilerThreads ever become non-JavaThreads, add them here
3374 }
3375
3376 // The system initialization in the library has three phases.
3377 //
3378 // Phase 1: java.lang.System class initialization
3379 // java.lang.System is a primordial class loaded and initialized
3380 // by the VM early during startup. java.lang.System.<clinit>
3381 // only does registerNatives and keeps the rest of the class
3382 // initialization work later until thread initialization completes.
3383 //
3384 // System.initPhase1 initializes the system properties, the static
3385 // fields in, out, and err. Set up java signal handlers, OS-specific
3386 // system settings, and thread group of the main thread.
3387 static void call_initPhase1(TRAPS) {
3388 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3389 instanceKlassHandle klass (THREAD, k);
3390
3391 JavaValue result(T_VOID);
3392 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3393 vmSymbols::void_method_signature(), CHECK);
3394 }
3395
3396 // Phase 2. Module system initialization
3397 // This will initialize the module system. Only java.base classes
3398 // can be loaded until phase 2 completes.
3399 //
3400 // Call System.initPhase2 after the compiler initialization and jsr292
3401 // classes get initialized because module initialization runs a lot of java
3402 // code, that for performance reasons, should be compiled. Also, this will
3403 // enable the startup code to use lambda and other language features in this
3404 // phase and onward.
3405 //
3406 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3407 static void call_initPhase2(TRAPS) {
3408 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3409
3410 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3411 instanceKlassHandle klass (THREAD, k);
3412
3413 JavaValue result(T_VOID);
3414 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3415 vmSymbols::void_method_signature(), CHECK);
3416 universe_post_module_init();
3417 }
3418
3419 // Phase 3. final setup - set security manager, system class loader and TCCL
3420 //
3421 // This will instantiate and set the security manager, set the system class
3422 // loader as well as the thread context class loader. The security manager
3423 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3424 // other modules or the application's classpath.
3425 static void call_initPhase3(TRAPS) {
3426 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3427 instanceKlassHandle klass (THREAD, k);
3428
3429 JavaValue result(T_VOID);
3430 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3431 vmSymbols::void_method_signature(), CHECK);
3432 }
3433
3434 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3435 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3436
3437 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3438 create_vm_init_libraries();
3439 }
3440
3441 initialize_class(vmSymbols::java_lang_String(), CHECK);
3442
3443 // Inject CompactStrings value after the static initializers for String ran.
3444 java_lang_String::set_compact_strings(CompactStrings);
3445
3446 // Initialize java_lang.System (needed before creating the thread)
3447 initialize_class(vmSymbols::java_lang_System(), CHECK);
3448 // The VM creates & returns objects of this class. Make sure it's initialized.
3449 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3450 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3451 Handle thread_group = create_initial_thread_group(CHECK);
3452 Universe::set_main_thread_group(thread_group());
3453 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3454 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3455 main_thread->set_threadObj(thread_object);
3456 // Set thread status to running since main thread has
3457 // been started and running.
3458 java_lang_Thread::set_thread_status(thread_object,
3459 java_lang_Thread::RUNNABLE);
3460
3461 // The VM creates objects of this class.
3462 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3463
3464 // The VM preresolves methods to these classes. Make sure that they get initialized
3465 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3466 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3467
3468 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3469 call_initPhase1(CHECK);
3470
3471 // get the Java runtime name after java.lang.System is initialized
3472 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3473 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3474
3475 // an instance of OutOfMemory exception has been allocated earlier
3476 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3477 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3478 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3479 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3480 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3481 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3482 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3483 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3484 }
3485
3486 void Threads::initialize_jsr292_core_classes(TRAPS) {
3487 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3488
3489 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3490 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3491 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3492 }
3493
3494 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3495 extern void JDK_Version_init();
3496
3497 // Preinitialize version info.
3498 VM_Version::early_initialize();
3499
3500 // Check version
3501 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3502
3503 // Initialize library-based TLS
3504 ThreadLocalStorage::init();
3505
3506 // Initialize the output stream module
3507 ostream_init();
3508
3509 // Process java launcher properties.
3510 Arguments::process_sun_java_launcher_properties(args);
3511
3512 // Initialize the os module
3513 os::init();
3514
3515 // Record VM creation timing statistics
3516 TraceVmCreationTime create_vm_timer;
3517 create_vm_timer.start();
3518
3519 // Initialize system properties.
3520 Arguments::init_system_properties();
3521
3522 // So that JDK version can be used as a discriminator when parsing arguments
3523 JDK_Version_init();
3524
3525 // Update/Initialize System properties after JDK version number is known
3526 Arguments::init_version_specific_system_properties();
3527
3528 // Make sure to initialize log configuration *before* parsing arguments
3529 LogConfiguration::initialize(create_vm_timer.begin_time());
3530
3531 // Parse arguments
3532 jint parse_result = Arguments::parse(args);
3533 if (parse_result != JNI_OK) return parse_result;
3534
3535 os::init_before_ergo();
3536
3537 jint ergo_result = Arguments::apply_ergo();
3538 if (ergo_result != JNI_OK) return ergo_result;
3539
3540 // Final check of all ranges after ergonomics which may change values.
3541 if (!CommandLineFlagRangeList::check_ranges()) {
3542 return JNI_EINVAL;
3543 }
3544
3545 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3546 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3547 if (!constraint_result) {
3548 return JNI_EINVAL;
3549 }
3550
3551 CommandLineFlagWriteableList::mark_startup();
3552
3553 if (PauseAtStartup) {
3554 os::pause();
3555 }
3556
3557 HOTSPOT_VM_INIT_BEGIN();
3558
3559 // Timing (must come after argument parsing)
3560 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3561
3562 // Initialize the os module after parsing the args
3563 jint os_init_2_result = os::init_2();
3564 if (os_init_2_result != JNI_OK) return os_init_2_result;
3565
3566 jint adjust_after_os_result = Arguments::adjust_after_os();
3567 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3568
3569 // Initialize output stream logging
3570 ostream_init_log();
3571
3572 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3573 // Must be before create_vm_init_agents()
3574 if (Arguments::init_libraries_at_startup()) {
3575 convert_vm_init_libraries_to_agents();
3576 }
3577
3578 // Launch -agentlib/-agentpath and converted -Xrun agents
3579 if (Arguments::init_agents_at_startup()) {
3580 create_vm_init_agents();
3581 }
3582
3583 // Initialize Threads state
3584 _thread_list = NULL;
3585 _number_of_threads = 0;
3586 _number_of_non_daemon_threads = 0;
3587
3588 // Initialize global data structures and create system classes in heap
3589 vm_init_globals();
3590
3591 #if INCLUDE_JVMCI
3592 if (JVMCICounterSize > 0) {
3593 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3594 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3595 } else {
3596 JavaThread::_jvmci_old_thread_counters = NULL;
3597 }
3598 #endif // INCLUDE_JVMCI
3599
3600 // Attach the main thread to this os thread
3601 JavaThread* main_thread = new JavaThread();
3602 main_thread->set_thread_state(_thread_in_vm);
3603 main_thread->initialize_thread_current();
3604 // must do this before set_active_handles
3605 main_thread->record_stack_base_and_size();
3606 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3607
3608 if (!main_thread->set_as_starting_thread()) {
3609 vm_shutdown_during_initialization(
3610 "Failed necessary internal allocation. Out of swap space");
3611 delete main_thread;
3612 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3613 return JNI_ENOMEM;
3614 }
3615
3616 // Enable guard page *after* os::create_main_thread(), otherwise it would
3617 // crash Linux VM, see notes in os_linux.cpp.
3618 main_thread->create_stack_guard_pages();
3619
3620 // Initialize Java-Level synchronization subsystem
3621 ObjectMonitor::Initialize();
3622
3623 // Initialize global modules
3624 jint status = init_globals();
3625 if (status != JNI_OK) {
3626 delete main_thread;
3627 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3628 return status;
3629 }
3630
3631 if (TRACE_INITIALIZE() != JNI_OK) {
3632 vm_exit_during_initialization("Failed to initialize tracing backend");
3633 }
3634
3635 // Should be done after the heap is fully created
3636 main_thread->cache_global_variables();
3637
3638 HandleMark hm;
3639
3640 { MutexLocker mu(Threads_lock);
3641 Threads::add(main_thread);
3642 }
3643
3644 // Any JVMTI raw monitors entered in onload will transition into
3645 // real raw monitor. VM is setup enough here for raw monitor enter.
3646 JvmtiExport::transition_pending_onload_raw_monitors();
3647
3648 // Create the VMThread
3649 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3650
3651 VMThread::create();
3652 Thread* vmthread = VMThread::vm_thread();
3653
3654 if (!os::create_thread(vmthread, os::vm_thread)) {
3655 vm_exit_during_initialization("Cannot create VM thread. "
3656 "Out of system resources.");
3657 }
3658
3659 // Wait for the VM thread to become ready, and VMThread::run to initialize
3660 // Monitors can have spurious returns, must always check another state flag
3661 {
3662 MutexLocker ml(Notify_lock);
3663 os::start_thread(vmthread);
3664 while (vmthread->active_handles() == NULL) {
3665 Notify_lock->wait();
3666 }
3667 }
3668 }
3669
3670 assert(Universe::is_fully_initialized(), "not initialized");
3671 if (VerifyDuringStartup) {
3672 // Make sure we're starting with a clean slate.
3673 VM_Verify verify_op;
3674 VMThread::execute(&verify_op);
3675 }
3676
3677 Thread* THREAD = Thread::current();
3678
3679 // At this point, the Universe is initialized, but we have not executed
3680 // any byte code. Now is a good time (the only time) to dump out the
3681 // internal state of the JVM for sharing.
3682 if (DumpSharedSpaces) {
3683 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3684 ShouldNotReachHere();
3685 }
3686
3687 // Always call even when there are not JVMTI environments yet, since environments
3688 // may be attached late and JVMTI must track phases of VM execution
3689 JvmtiExport::enter_early_start_phase();
3690
3691 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3692 JvmtiExport::post_early_vm_start();
3693
3694 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3695
3696 // We need this for ClassDataSharing - the initial vm.info property is set
3697 // with the default value of CDS "sharing" which may be reset through
3698 // command line options.
3699 reset_vm_info_property(CHECK_JNI_ERR);
3700
3701 quicken_jni_functions();
3702
3703 // No more stub generation allowed after that point.
3704 StubCodeDesc::freeze();
3705
3706 // Set flag that basic initialization has completed. Used by exceptions and various
3707 // debug stuff, that does not work until all basic classes have been initialized.
3708 set_init_completed();
3709
3710 LogConfiguration::post_initialize();
3711 Metaspace::post_initialize();
3712
3713 HOTSPOT_VM_INIT_END();
3714
3715 // record VM initialization completion time
3716 #if INCLUDE_MANAGEMENT
3717 Management::record_vm_init_completed();
3718 #endif // INCLUDE_MANAGEMENT
3719
3720 // Signal Dispatcher needs to be started before VMInit event is posted
3721 os::signal_init();
3722
3723 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3724 if (!DisableAttachMechanism) {
3725 AttachListener::vm_start();
3726 if (StartAttachListener || AttachListener::init_at_startup()) {
3727 AttachListener::init();
3728 }
3729 }
3730
3731 // Launch -Xrun agents
3732 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3733 // back-end can launch with -Xdebug -Xrunjdwp.
3734 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3735 create_vm_init_libraries();
3736 }
3737
3738 if (CleanChunkPoolAsync) {
3739 Chunk::start_chunk_pool_cleaner_task();
3740 }
3741
3742 // initialize compiler(s)
3743 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3744 CompileBroker::compilation_init(CHECK_JNI_ERR);
3745 #endif
3746
3747 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3748 // It is done after compilers are initialized, because otherwise compilations of
3749 // signature polymorphic MH intrinsics can be missed
3750 // (see SystemDictionary::find_method_handle_intrinsic).
3751 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3752
3753 // This will initialize the module system. Only java.base classes can be
3754 // loaded until phase 2 completes
3755 call_initPhase2(CHECK_JNI_ERR);
3756
3757 // Always call even when there are not JVMTI environments yet, since environments
3758 // may be attached late and JVMTI must track phases of VM execution
3759 JvmtiExport::enter_start_phase();
3760
3761 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3762 JvmtiExport::post_vm_start();
3763
3764 // Final system initialization including security manager and system class loader
3765 call_initPhase3(CHECK_JNI_ERR);
3766
3767 // cache the system class loader
3768 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3769
3770 #if INCLUDE_JVMCI
3771 if (EnableJVMCI) {
3772 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3773 // The JVMCI Java initialization code will read this flag and
3774 // do the printing if it's set.
3775 bool init = JVMCIPrintProperties;
3776
3777 if (!init) {
3778 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3779 // compilations via JVMCI will not actually block until JVMCI is initialized.
3780 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3781 }
3782
3783 if (init) {
3784 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3785 }
3786 }
3787 #endif
3788
3789 // Always call even when there are not JVMTI environments yet, since environments
3790 // may be attached late and JVMTI must track phases of VM execution
3791 JvmtiExport::enter_live_phase();
3792
3793 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3794 JvmtiExport::post_vm_initialized();
3795
3796 if (TRACE_START() != JNI_OK) {
3797 vm_exit_during_initialization("Failed to start tracing backend.");
3798 }
3799
3800 #if INCLUDE_MANAGEMENT
3801 Management::initialize(THREAD);
3802
3803 if (HAS_PENDING_EXCEPTION) {
3804 // management agent fails to start possibly due to
3805 // configuration problem and is responsible for printing
3806 // stack trace if appropriate. Simply exit VM.
3807 vm_exit(1);
3808 }
3809 #endif // INCLUDE_MANAGEMENT
3810
3811 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3812 if (MemProfiling) MemProfiler::engage();
3813 StatSampler::engage();
3814 if (CheckJNICalls) JniPeriodicChecker::engage();
3815
3816 BiasedLocking::init();
3817
3818 #if INCLUDE_RTM_OPT
3819 RTMLockingCounters::init();
3820 #endif
3821
3822 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3823 call_postVMInitHook(THREAD);
3824 // The Java side of PostVMInitHook.run must deal with all
3825 // exceptions and provide means of diagnosis.
3826 if (HAS_PENDING_EXCEPTION) {
3827 CLEAR_PENDING_EXCEPTION;
3828 }
3829 }
3830
3831 {
3832 MutexLocker ml(PeriodicTask_lock);
3833 // Make sure the WatcherThread can be started by WatcherThread::start()
3834 // or by dynamic enrollment.
3835 WatcherThread::make_startable();
3836 // Start up the WatcherThread if there are any periodic tasks
3837 // NOTE: All PeriodicTasks should be registered by now. If they
3838 // aren't, late joiners might appear to start slowly (we might
3839 // take a while to process their first tick).
3840 if (PeriodicTask::num_tasks() > 0) {
3841 WatcherThread::start();
3842 }
3843 }
3844
3845 create_vm_timer.end();
3846 #ifdef ASSERT
3847 _vm_complete = true;
3848 #endif
3849 return JNI_OK;
3850 }
3851
3852 // type for the Agent_OnLoad and JVM_OnLoad entry points
3853 extern "C" {
3854 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3855 }
3856 // Find a command line agent library and return its entry point for
3857 // -agentlib: -agentpath: -Xrun
3858 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3859 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3860 const char *on_load_symbols[],
3861 size_t num_symbol_entries) {
3862 OnLoadEntry_t on_load_entry = NULL;
3863 void *library = NULL;
3864
3865 if (!agent->valid()) {
3866 char buffer[JVM_MAXPATHLEN];
3867 char ebuf[1024] = "";
3868 const char *name = agent->name();
3869 const char *msg = "Could not find agent library ";
3870
3871 // First check to see if agent is statically linked into executable
3872 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3873 library = agent->os_lib();
3874 } else if (agent->is_absolute_path()) {
3875 library = os::dll_load(name, ebuf, sizeof ebuf);
3876 if (library == NULL) {
3877 const char *sub_msg = " in absolute path, with error: ";
3878 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3879 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3880 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3881 // If we can't find the agent, exit.
3882 vm_exit_during_initialization(buf, NULL);
3883 FREE_C_HEAP_ARRAY(char, buf);
3884 }
3885 } else {
3886 // Try to load the agent from the standard dll directory
3887 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3888 name)) {
3889 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3890 }
3891 if (library == NULL) { // Try the local directory
3892 char ns[1] = {0};
3893 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3894 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3895 }
3896 if (library == NULL) {
3897 const char *sub_msg = " on the library path, with error: ";
3898 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3899 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3900 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3901 // If we can't find the agent, exit.
3902 vm_exit_during_initialization(buf, NULL);
3903 FREE_C_HEAP_ARRAY(char, buf);
3904 }
3905 }
3906 }
3907 agent->set_os_lib(library);
3908 agent->set_valid();
3909 }
3910
3911 // Find the OnLoad function.
3912 on_load_entry =
3913 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3914 false,
3915 on_load_symbols,
3916 num_symbol_entries));
3917 return on_load_entry;
3918 }
3919
3920 // Find the JVM_OnLoad entry point
3921 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3922 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3923 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3924 }
3925
3926 // Find the Agent_OnLoad entry point
3927 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3928 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3929 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3930 }
3931
3932 // For backwards compatibility with -Xrun
3933 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3934 // treated like -agentpath:
3935 // Must be called before agent libraries are created
3936 void Threads::convert_vm_init_libraries_to_agents() {
3937 AgentLibrary* agent;
3938 AgentLibrary* next;
3939
3940 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3941 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3942 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3943
3944 // If there is an JVM_OnLoad function it will get called later,
3945 // otherwise see if there is an Agent_OnLoad
3946 if (on_load_entry == NULL) {
3947 on_load_entry = lookup_agent_on_load(agent);
3948 if (on_load_entry != NULL) {
3949 // switch it to the agent list -- so that Agent_OnLoad will be called,
3950 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3951 Arguments::convert_library_to_agent(agent);
3952 } else {
3953 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3954 }
3955 }
3956 }
3957 }
3958
3959 // Create agents for -agentlib: -agentpath: and converted -Xrun
3960 // Invokes Agent_OnLoad
3961 // Called very early -- before JavaThreads exist
3962 void Threads::create_vm_init_agents() {
3963 extern struct JavaVM_ main_vm;
3964 AgentLibrary* agent;
3965
3966 JvmtiExport::enter_onload_phase();
3967
3968 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3969 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3970
3971 if (on_load_entry != NULL) {
3972 // Invoke the Agent_OnLoad function
3973 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3974 if (err != JNI_OK) {
3975 vm_exit_during_initialization("agent library failed to init", agent->name());
3976 }
3977 } else {
3978 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3979 }
3980 }
3981 JvmtiExport::enter_primordial_phase();
3982 }
3983
3984 extern "C" {
3985 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3986 }
3987
3988 void Threads::shutdown_vm_agents() {
3989 // Send any Agent_OnUnload notifications
3990 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3991 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3992 extern struct JavaVM_ main_vm;
3993 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3994
3995 // Find the Agent_OnUnload function.
3996 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3997 os::find_agent_function(agent,
3998 false,
3999 on_unload_symbols,
4000 num_symbol_entries));
4001
4002 // Invoke the Agent_OnUnload function
4003 if (unload_entry != NULL) {
4004 JavaThread* thread = JavaThread::current();
4005 ThreadToNativeFromVM ttn(thread);
4006 HandleMark hm(thread);
4007 (*unload_entry)(&main_vm);
4008 }
4009 }
4010 }
4011
4012 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4013 // Invokes JVM_OnLoad
4014 void Threads::create_vm_init_libraries() {
4015 extern struct JavaVM_ main_vm;
4016 AgentLibrary* agent;
4017
4018 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4019 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4020
4021 if (on_load_entry != NULL) {
4022 // Invoke the JVM_OnLoad function
4023 JavaThread* thread = JavaThread::current();
4024 ThreadToNativeFromVM ttn(thread);
4025 HandleMark hm(thread);
4026 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4027 if (err != JNI_OK) {
4028 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4029 }
4030 } else {
4031 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4032 }
4033 }
4034 }
4035
4036 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4037 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4038
4039 JavaThread* java_thread = NULL;
4040 // Sequential search for now. Need to do better optimization later.
4041 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4042 oop tobj = thread->threadObj();
4043 if (!thread->is_exiting() &&
4044 tobj != NULL &&
4045 java_tid == java_lang_Thread::thread_id(tobj)) {
4046 java_thread = thread;
4047 break;
4048 }
4049 }
4050 return java_thread;
4051 }
4052
4053
4054 // Last thread running calls java.lang.Shutdown.shutdown()
4055 void JavaThread::invoke_shutdown_hooks() {
4056 HandleMark hm(this);
4057
4058 // We could get here with a pending exception, if so clear it now.
4059 if (this->has_pending_exception()) {
4060 this->clear_pending_exception();
4061 }
4062
4063 EXCEPTION_MARK;
4064 Klass* k =
4065 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4066 THREAD);
4067 if (k != NULL) {
4068 // SystemDictionary::resolve_or_null will return null if there was
4069 // an exception. If we cannot load the Shutdown class, just don't
4070 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4071 // and finalizers (if runFinalizersOnExit is set) won't be run.
4072 // Note that if a shutdown hook was registered or runFinalizersOnExit
4073 // was called, the Shutdown class would have already been loaded
4074 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4075 instanceKlassHandle shutdown_klass (THREAD, k);
4076 JavaValue result(T_VOID);
4077 JavaCalls::call_static(&result,
4078 shutdown_klass,
4079 vmSymbols::shutdown_method_name(),
4080 vmSymbols::void_method_signature(),
4081 THREAD);
4082 }
4083 CLEAR_PENDING_EXCEPTION;
4084 }
4085
4086 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4087 // the program falls off the end of main(). Another VM exit path is through
4088 // vm_exit() when the program calls System.exit() to return a value or when
4089 // there is a serious error in VM. The two shutdown paths are not exactly
4090 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4091 // and VM_Exit op at VM level.
4092 //
4093 // Shutdown sequence:
4094 // + Shutdown native memory tracking if it is on
4095 // + Wait until we are the last non-daemon thread to execute
4096 // <-- every thing is still working at this moment -->
4097 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4098 // shutdown hooks, run finalizers if finalization-on-exit
4099 // + Call before_exit(), prepare for VM exit
4100 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4101 // currently the only user of this mechanism is File.deleteOnExit())
4102 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4103 // post thread end and vm death events to JVMTI,
4104 // stop signal thread
4105 // + Call JavaThread::exit(), it will:
4106 // > release JNI handle blocks, remove stack guard pages
4107 // > remove this thread from Threads list
4108 // <-- no more Java code from this thread after this point -->
4109 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4110 // the compiler threads at safepoint
4111 // <-- do not use anything that could get blocked by Safepoint -->
4112 // + Disable tracing at JNI/JVM barriers
4113 // + Set _vm_exited flag for threads that are still running native code
4114 // + Delete this thread
4115 // + Call exit_globals()
4116 // > deletes tty
4117 // > deletes PerfMemory resources
4118 // + Return to caller
4119
4120 bool Threads::destroy_vm() {
4121 JavaThread* thread = JavaThread::current();
4122
4123 #ifdef ASSERT
4124 _vm_complete = false;
4125 #endif
4126 // Wait until we are the last non-daemon thread to execute
4127 { MutexLocker nu(Threads_lock);
4128 while (Threads::number_of_non_daemon_threads() > 1)
4129 // This wait should make safepoint checks, wait without a timeout,
4130 // and wait as a suspend-equivalent condition.
4131 //
4132 // Note: If the FlatProfiler is running and this thread is waiting
4133 // for another non-daemon thread to finish, then the FlatProfiler
4134 // is waiting for the external suspend request on this thread to
4135 // complete. wait_for_ext_suspend_completion() will eventually
4136 // timeout, but that takes time. Making this wait a suspend-
4137 // equivalent condition solves that timeout problem.
4138 //
4139 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4140 Mutex::_as_suspend_equivalent_flag);
4141 }
4142
4143 // Hang forever on exit if we are reporting an error.
4144 if (ShowMessageBoxOnError && is_error_reported()) {
4145 os::infinite_sleep();
4146 }
4147 os::wait_for_keypress_at_exit();
4148
4149 // run Java level shutdown hooks
4150 thread->invoke_shutdown_hooks();
4151
4152 before_exit(thread);
4153
4154 thread->exit(true);
4155
4156 // Stop VM thread.
4157 {
4158 // 4945125 The vm thread comes to a safepoint during exit.
4159 // GC vm_operations can get caught at the safepoint, and the
4160 // heap is unparseable if they are caught. Grab the Heap_lock
4161 // to prevent this. The GC vm_operations will not be able to
4162 // queue until after the vm thread is dead. After this point,
4163 // we'll never emerge out of the safepoint before the VM exits.
4164
4165 MutexLocker ml(Heap_lock);
4166
4167 VMThread::wait_for_vm_thread_exit();
4168 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4169 VMThread::destroy();
4170 }
4171
4172 // clean up ideal graph printers
4173 #if defined(COMPILER2) && !defined(PRODUCT)
4174 IdealGraphPrinter::clean_up();
4175 #endif
4176
4177 // Now, all Java threads are gone except daemon threads. Daemon threads
4178 // running Java code or in VM are stopped by the Safepoint. However,
4179 // daemon threads executing native code are still running. But they
4180 // will be stopped at native=>Java/VM barriers. Note that we can't
4181 // simply kill or suspend them, as it is inherently deadlock-prone.
4182
4183 VM_Exit::set_vm_exited();
4184
4185 notify_vm_shutdown();
4186
4187 delete thread;
4188
4189 #if INCLUDE_JVMCI
4190 if (JVMCICounterSize > 0) {
4191 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4192 }
4193 #endif
4194
4195 // exit_globals() will delete tty
4196 exit_globals();
4197
4198 LogConfiguration::finalize();
4199
4200 return true;
4201 }
4202
4203
4204 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4205 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4206 return is_supported_jni_version(version);
4207 }
4208
4209
4210 jboolean Threads::is_supported_jni_version(jint version) {
4211 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4212 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4213 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4214 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4215 if (version == JNI_VERSION_9) return JNI_TRUE;
4216 return JNI_FALSE;
4217 }
4218
4219
4220 void Threads::add(JavaThread* p, bool force_daemon) {
4221 // The threads lock must be owned at this point
4222 assert_locked_or_safepoint(Threads_lock);
4223
4224 // See the comment for this method in thread.hpp for its purpose and
4225 // why it is called here.
4226 p->initialize_queues();
4227 p->set_next(_thread_list);
4228 _thread_list = p;
4229 _number_of_threads++;
4230 oop threadObj = p->threadObj();
4231 bool daemon = true;
4232 // Bootstrapping problem: threadObj can be null for initial
4233 // JavaThread (or for threads attached via JNI)
4234 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4235 _number_of_non_daemon_threads++;
4236 daemon = false;
4237 }
4238
4239 ThreadService::add_thread(p, daemon);
4240
4241 // Possible GC point.
4242 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4243 }
4244
4245 void Threads::remove(JavaThread* p) {
4246 // Extra scope needed for Thread_lock, so we can check
4247 // that we do not remove thread without safepoint code notice
4248 { MutexLocker ml(Threads_lock);
4249
4250 assert(includes(p), "p must be present");
4251
4252 JavaThread* current = _thread_list;
4253 JavaThread* prev = NULL;
4254
4255 while (current != p) {
4256 prev = current;
4257 current = current->next();
4258 }
4259
4260 if (prev) {
4261 prev->set_next(current->next());
4262 } else {
4263 _thread_list = p->next();
4264 }
4265 _number_of_threads--;
4266 oop threadObj = p->threadObj();
4267 bool daemon = true;
4268 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4269 _number_of_non_daemon_threads--;
4270 daemon = false;
4271
4272 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4273 // on destroy_vm will wake up.
4274 if (number_of_non_daemon_threads() == 1) {
4275 Threads_lock->notify_all();
4276 }
4277 }
4278 ThreadService::remove_thread(p, daemon);
4279
4280 // Make sure that safepoint code disregard this thread. This is needed since
4281 // the thread might mess around with locks after this point. This can cause it
4282 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4283 // of this thread since it is removed from the queue.
4284 p->set_terminated_value();
4285 } // unlock Threads_lock
4286
4287 // Since Events::log uses a lock, we grab it outside the Threads_lock
4288 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4289 }
4290
4291 // Threads_lock must be held when this is called (or must be called during a safepoint)
4292 bool Threads::includes(JavaThread* p) {
4293 assert(Threads_lock->is_locked(), "sanity check");
4294 ALL_JAVA_THREADS(q) {
4295 if (q == p) {
4296 return true;
4297 }
4298 }
4299 return false;
4300 }
4301
4302 // Operations on the Threads list for GC. These are not explicitly locked,
4303 // but the garbage collector must provide a safe context for them to run.
4304 // In particular, these things should never be called when the Threads_lock
4305 // is held by some other thread. (Note: the Safepoint abstraction also
4306 // uses the Threads_lock to guarantee this property. It also makes sure that
4307 // all threads gets blocked when exiting or starting).
4308
4309 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4310 ALL_JAVA_THREADS(p) {
4311 p->oops_do(f, cf);
4312 }
4313 VMThread::vm_thread()->oops_do(f, cf);
4314 }
4315
4316 void Threads::change_thread_claim_parity() {
4317 // Set the new claim parity.
4318 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4319 "Not in range.");
4320 _thread_claim_parity++;
4321 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4322 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4323 "Not in range.");
4324 }
4325
4326 #ifdef ASSERT
4327 void Threads::assert_all_threads_claimed() {
4328 ALL_JAVA_THREADS(p) {
4329 const int thread_parity = p->oops_do_parity();
4330 assert((thread_parity == _thread_claim_parity),
4331 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4332 }
4333 }
4334 #endif // ASSERT
4335
4336 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4337 int cp = Threads::thread_claim_parity();
4338 ALL_JAVA_THREADS(p) {
4339 if (p->claim_oops_do(is_par, cp)) {
4340 p->oops_do(f, cf);
4341 }
4342 }
4343 VMThread* vmt = VMThread::vm_thread();
4344 if (vmt->claim_oops_do(is_par, cp)) {
4345 vmt->oops_do(f, cf);
4346 }
4347 }
4348
4349 #if INCLUDE_ALL_GCS
4350 // Used by ParallelScavenge
4351 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4352 ALL_JAVA_THREADS(p) {
4353 q->enqueue(new ThreadRootsTask(p));
4354 }
4355 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4356 }
4357
4358 // Used by Parallel Old
4359 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4360 ALL_JAVA_THREADS(p) {
4361 q->enqueue(new ThreadRootsMarkingTask(p));
4362 }
4363 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4364 }
4365 #endif // INCLUDE_ALL_GCS
4366
4367 void Threads::nmethods_do(CodeBlobClosure* cf) {
4368 ALL_JAVA_THREADS(p) {
4369 // This is used by the code cache sweeper to mark nmethods that are active
4370 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4371 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4372 if(!p->is_Code_cache_sweeper_thread()) {
4373 p->nmethods_do(cf);
4374 }
4375 }
4376 }
4377
4378 void Threads::metadata_do(void f(Metadata*)) {
4379 ALL_JAVA_THREADS(p) {
4380 p->metadata_do(f);
4381 }
4382 }
4383
4384 class ThreadHandlesClosure : public ThreadClosure {
4385 void (*_f)(Metadata*);
4386 public:
4387 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4388 virtual void do_thread(Thread* thread) {
4389 thread->metadata_handles_do(_f);
4390 }
4391 };
4392
4393 void Threads::metadata_handles_do(void f(Metadata*)) {
4394 // Only walk the Handles in Thread.
4395 ThreadHandlesClosure handles_closure(f);
4396 threads_do(&handles_closure);
4397 }
4398
4399 void Threads::deoptimized_wrt_marked_nmethods() {
4400 ALL_JAVA_THREADS(p) {
4401 p->deoptimized_wrt_marked_nmethods();
4402 }
4403 }
4404
4405
4406 // Get count Java threads that are waiting to enter the specified monitor.
4407 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4408 address monitor,
4409 bool doLock) {
4410 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4411 "must grab Threads_lock or be at safepoint");
4412 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4413
4414 int i = 0;
4415 {
4416 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4417 ALL_JAVA_THREADS(p) {
4418 if (!p->can_call_java()) continue;
4419
4420 address pending = (address)p->current_pending_monitor();
4421 if (pending == monitor) { // found a match
4422 if (i < count) result->append(p); // save the first count matches
4423 i++;
4424 }
4425 }
4426 }
4427 return result;
4428 }
4429
4430
4431 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4432 bool doLock) {
4433 assert(doLock ||
4434 Threads_lock->owned_by_self() ||
4435 SafepointSynchronize::is_at_safepoint(),
4436 "must grab Threads_lock or be at safepoint");
4437
4438 // NULL owner means not locked so we can skip the search
4439 if (owner == NULL) return NULL;
4440
4441 {
4442 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4443 ALL_JAVA_THREADS(p) {
4444 // first, see if owner is the address of a Java thread
4445 if (owner == (address)p) return p;
4446 }
4447 }
4448 // Cannot assert on lack of success here since this function may be
4449 // used by code that is trying to report useful problem information
4450 // like deadlock detection.
4451 if (UseHeavyMonitors) return NULL;
4452
4453 // If we didn't find a matching Java thread and we didn't force use of
4454 // heavyweight monitors, then the owner is the stack address of the
4455 // Lock Word in the owning Java thread's stack.
4456 //
4457 JavaThread* the_owner = NULL;
4458 {
4459 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4460 ALL_JAVA_THREADS(q) {
4461 if (q->is_lock_owned(owner)) {
4462 the_owner = q;
4463 break;
4464 }
4465 }
4466 }
4467 // cannot assert on lack of success here; see above comment
4468 return the_owner;
4469 }
4470
4471 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4472 void Threads::print_on(outputStream* st, bool print_stacks,
4473 bool internal_format, bool print_concurrent_locks) {
4474 char buf[32];
4475 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4476
4477 st->print_cr("Full thread dump %s (%s %s):",
4478 Abstract_VM_Version::vm_name(),
4479 Abstract_VM_Version::vm_release(),
4480 Abstract_VM_Version::vm_info_string());
4481 st->cr();
4482
4483 #if INCLUDE_SERVICES
4484 // Dump concurrent locks
4485 ConcurrentLocksDump concurrent_locks;
4486 if (print_concurrent_locks) {
4487 concurrent_locks.dump_at_safepoint();
4488 }
4489 #endif // INCLUDE_SERVICES
4490
4491 ALL_JAVA_THREADS(p) {
4492 ResourceMark rm;
4493 p->print_on(st);
4494 if (print_stacks) {
4495 if (internal_format) {
4496 p->trace_stack();
4497 } else {
4498 p->print_stack_on(st);
4499 }
4500 }
4501 st->cr();
4502 #if INCLUDE_SERVICES
4503 if (print_concurrent_locks) {
4504 concurrent_locks.print_locks_on(p, st);
4505 }
4506 #endif // INCLUDE_SERVICES
4507 }
4508
4509 VMThread::vm_thread()->print_on(st);
4510 st->cr();
4511 Universe::heap()->print_gc_threads_on(st);
4512 WatcherThread* wt = WatcherThread::watcher_thread();
4513 if (wt != NULL) {
4514 wt->print_on(st);
4515 st->cr();
4516 }
4517 st->flush();
4518 }
4519
4520 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4521 int buflen, bool* found_current) {
4522 if (this_thread != NULL) {
4523 bool is_current = (current == this_thread);
4524 *found_current = *found_current || is_current;
4525 st->print("%s", is_current ? "=>" : " ");
4526
4527 st->print(PTR_FORMAT, p2i(this_thread));
4528 st->print(" ");
4529 this_thread->print_on_error(st, buf, buflen);
4530 st->cr();
4531 }
4532 }
4533
4534 class PrintOnErrorClosure : public ThreadClosure {
4535 outputStream* _st;
4536 Thread* _current;
4537 char* _buf;
4538 int _buflen;
4539 bool* _found_current;
4540 public:
4541 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4542 int buflen, bool* found_current) :
4543 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4544
4545 virtual void do_thread(Thread* thread) {
4546 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4547 }
4548 };
4549
4550 // Threads::print_on_error() is called by fatal error handler. It's possible
4551 // that VM is not at safepoint and/or current thread is inside signal handler.
4552 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4553 // memory (even in resource area), it might deadlock the error handler.
4554 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4555 int buflen) {
4556 bool found_current = false;
4557 st->print_cr("Java Threads: ( => current thread )");
4558 ALL_JAVA_THREADS(thread) {
4559 print_on_error(thread, st, current, buf, buflen, &found_current);
4560 }
4561 st->cr();
4562
4563 st->print_cr("Other Threads:");
4564 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4565 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4566
4567 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4568 Universe::heap()->gc_threads_do(&print_closure);
4569
4570 if (!found_current) {
4571 st->cr();
4572 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4573 current->print_on_error(st, buf, buflen);
4574 st->cr();
4575 }
4576 st->cr();
4577 st->print_cr("Threads with active compile tasks:");
4578 print_threads_compiling(st, buf, buflen);
4579 }
4580
4581 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4582 ALL_JAVA_THREADS(thread) {
4583 if (thread->is_Compiler_thread()) {
4584 CompilerThread* ct = (CompilerThread*) thread;
4585 if (ct->task() != NULL) {
4586 thread->print_name_on_error(st, buf, buflen);
4587 ct->task()->print(st, NULL, true, true);
4588 }
4589 }
4590 }
4591 }
4592
4593
4594 // Internal SpinLock and Mutex
4595 // Based on ParkEvent
4596
4597 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4598 //
4599 // We employ SpinLocks _only for low-contention, fixed-length
4600 // short-duration critical sections where we're concerned
4601 // about native mutex_t or HotSpot Mutex:: latency.
4602 // The mux construct provides a spin-then-block mutual exclusion
4603 // mechanism.
4604 //
4605 // Testing has shown that contention on the ListLock guarding gFreeList
4606 // is common. If we implement ListLock as a simple SpinLock it's common
4607 // for the JVM to devolve to yielding with little progress. This is true
4608 // despite the fact that the critical sections protected by ListLock are
4609 // extremely short.
4610 //
4611 // TODO-FIXME: ListLock should be of type SpinLock.
4612 // We should make this a 1st-class type, integrated into the lock
4613 // hierarchy as leaf-locks. Critically, the SpinLock structure
4614 // should have sufficient padding to avoid false-sharing and excessive
4615 // cache-coherency traffic.
4616
4617
4618 typedef volatile int SpinLockT;
4619
4620 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4621 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4622 return; // normal fast-path return
4623 }
4624
4625 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4626 TEVENT(SpinAcquire - ctx);
4627 int ctr = 0;
4628 int Yields = 0;
4629 for (;;) {
4630 while (*adr != 0) {
4631 ++ctr;
4632 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4633 if (Yields > 5) {
4634 os::naked_short_sleep(1);
4635 } else {
4636 os::naked_yield();
4637 ++Yields;
4638 }
4639 } else {
4640 SpinPause();
4641 }
4642 }
4643 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4644 }
4645 }
4646
4647 void Thread::SpinRelease(volatile int * adr) {
4648 assert(*adr != 0, "invariant");
4649 OrderAccess::fence(); // guarantee at least release consistency.
4650 // Roach-motel semantics.
4651 // It's safe if subsequent LDs and STs float "up" into the critical section,
4652 // but prior LDs and STs within the critical section can't be allowed
4653 // to reorder or float past the ST that releases the lock.
4654 // Loads and stores in the critical section - which appear in program
4655 // order before the store that releases the lock - must also appear
4656 // before the store that releases the lock in memory visibility order.
4657 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4658 // the ST of 0 into the lock-word which releases the lock, so fence
4659 // more than covers this on all platforms.
4660 *adr = 0;
4661 }
4662
4663 // muxAcquire and muxRelease:
4664 //
4665 // * muxAcquire and muxRelease support a single-word lock-word construct.
4666 // The LSB of the word is set IFF the lock is held.
4667 // The remainder of the word points to the head of a singly-linked list
4668 // of threads blocked on the lock.
4669 //
4670 // * The current implementation of muxAcquire-muxRelease uses its own
4671 // dedicated Thread._MuxEvent instance. If we're interested in
4672 // minimizing the peak number of extant ParkEvent instances then
4673 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4674 // as certain invariants were satisfied. Specifically, care would need
4675 // to be taken with regards to consuming unpark() "permits".
4676 // A safe rule of thumb is that a thread would never call muxAcquire()
4677 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4678 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4679 // consume an unpark() permit intended for monitorenter, for instance.
4680 // One way around this would be to widen the restricted-range semaphore
4681 // implemented in park(). Another alternative would be to provide
4682 // multiple instances of the PlatformEvent() for each thread. One
4683 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4684 //
4685 // * Usage:
4686 // -- Only as leaf locks
4687 // -- for short-term locking only as muxAcquire does not perform
4688 // thread state transitions.
4689 //
4690 // Alternatives:
4691 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4692 // but with parking or spin-then-park instead of pure spinning.
4693 // * Use Taura-Oyama-Yonenzawa locks.
4694 // * It's possible to construct a 1-0 lock if we encode the lockword as
4695 // (List,LockByte). Acquire will CAS the full lockword while Release
4696 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4697 // acquiring threads use timers (ParkTimed) to detect and recover from
4698 // the stranding window. Thread/Node structures must be aligned on 256-byte
4699 // boundaries by using placement-new.
4700 // * Augment MCS with advisory back-link fields maintained with CAS().
4701 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4702 // The validity of the backlinks must be ratified before we trust the value.
4703 // If the backlinks are invalid the exiting thread must back-track through the
4704 // the forward links, which are always trustworthy.
4705 // * Add a successor indication. The LockWord is currently encoded as
4706 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4707 // to provide the usual futile-wakeup optimization.
4708 // See RTStt for details.
4709 // * Consider schedctl.sc_nopreempt to cover the critical section.
4710 //
4711
4712
4713 typedef volatile intptr_t MutexT; // Mux Lock-word
4714 enum MuxBits { LOCKBIT = 1 };
4715
4716 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4717 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4718 if (w == 0) return;
4719 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4720 return;
4721 }
4722
4723 TEVENT(muxAcquire - Contention);
4724 ParkEvent * const Self = Thread::current()->_MuxEvent;
4725 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4726 for (;;) {
4727 int its = (os::is_MP() ? 100 : 0) + 1;
4728
4729 // Optional spin phase: spin-then-park strategy
4730 while (--its >= 0) {
4731 w = *Lock;
4732 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4733 return;
4734 }
4735 }
4736
4737 Self->reset();
4738 Self->OnList = intptr_t(Lock);
4739 // The following fence() isn't _strictly necessary as the subsequent
4740 // CAS() both serializes execution and ratifies the fetched *Lock value.
4741 OrderAccess::fence();
4742 for (;;) {
4743 w = *Lock;
4744 if ((w & LOCKBIT) == 0) {
4745 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4746 Self->OnList = 0; // hygiene - allows stronger asserts
4747 return;
4748 }
4749 continue; // Interference -- *Lock changed -- Just retry
4750 }
4751 assert(w & LOCKBIT, "invariant");
4752 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4753 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4754 }
4755
4756 while (Self->OnList != 0) {
4757 Self->park();
4758 }
4759 }
4760 }
4761
4762 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4763 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4764 if (w == 0) return;
4765 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4766 return;
4767 }
4768
4769 TEVENT(muxAcquire - Contention);
4770 ParkEvent * ReleaseAfter = NULL;
4771 if (ev == NULL) {
4772 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4773 }
4774 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4775 for (;;) {
4776 guarantee(ev->OnList == 0, "invariant");
4777 int its = (os::is_MP() ? 100 : 0) + 1;
4778
4779 // Optional spin phase: spin-then-park strategy
4780 while (--its >= 0) {
4781 w = *Lock;
4782 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4783 if (ReleaseAfter != NULL) {
4784 ParkEvent::Release(ReleaseAfter);
4785 }
4786 return;
4787 }
4788 }
4789
4790 ev->reset();
4791 ev->OnList = intptr_t(Lock);
4792 // The following fence() isn't _strictly necessary as the subsequent
4793 // CAS() both serializes execution and ratifies the fetched *Lock value.
4794 OrderAccess::fence();
4795 for (;;) {
4796 w = *Lock;
4797 if ((w & LOCKBIT) == 0) {
4798 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4799 ev->OnList = 0;
4800 // We call ::Release while holding the outer lock, thus
4801 // artificially lengthening the critical section.
4802 // Consider deferring the ::Release() until the subsequent unlock(),
4803 // after we've dropped the outer lock.
4804 if (ReleaseAfter != NULL) {
4805 ParkEvent::Release(ReleaseAfter);
4806 }
4807 return;
4808 }
4809 continue; // Interference -- *Lock changed -- Just retry
4810 }
4811 assert(w & LOCKBIT, "invariant");
4812 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4813 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4814 }
4815
4816 while (ev->OnList != 0) {
4817 ev->park();
4818 }
4819 }
4820 }
4821
4822 // Release() must extract a successor from the list and then wake that thread.
4823 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4824 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4825 // Release() would :
4826 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4827 // (B) Extract a successor from the private list "in-hand"
4828 // (C) attempt to CAS() the residual back into *Lock over null.
4829 // If there were any newly arrived threads and the CAS() would fail.
4830 // In that case Release() would detach the RATs, re-merge the list in-hand
4831 // with the RATs and repeat as needed. Alternately, Release() might
4832 // detach and extract a successor, but then pass the residual list to the wakee.
4833 // The wakee would be responsible for reattaching and remerging before it
4834 // competed for the lock.
4835 //
4836 // Both "pop" and DMR are immune from ABA corruption -- there can be
4837 // multiple concurrent pushers, but only one popper or detacher.
4838 // This implementation pops from the head of the list. This is unfair,
4839 // but tends to provide excellent throughput as hot threads remain hot.
4840 // (We wake recently run threads first).
4841 //
4842 // All paths through muxRelease() will execute a CAS.
4843 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4844 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4845 // executed within the critical section are complete and globally visible before the
4846 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4847 void Thread::muxRelease(volatile intptr_t * Lock) {
4848 for (;;) {
4849 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4850 assert(w & LOCKBIT, "invariant");
4851 if (w == LOCKBIT) return;
4852 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4853 assert(List != NULL, "invariant");
4854 assert(List->OnList == intptr_t(Lock), "invariant");
4855 ParkEvent * const nxt = List->ListNext;
4856 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4857
4858 // The following CAS() releases the lock and pops the head element.
4859 // The CAS() also ratifies the previously fetched lock-word value.
4860 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4861 continue;
4862 }
4863 List->OnList = 0;
4864 OrderAccess::fence();
4865 List->unpark();
4866 return;
4867 }
4868 }
4869
4870
4871 void Threads::verify() {
4872 ALL_JAVA_THREADS(p) {
4873 p->verify();
4874 }
4875 VMThread* thread = VMThread::vm_thread();
4876 if (thread != NULL) thread->verify();
4877 }