1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "memory/metaspaceShared.hpp"
45 #include "memory/oopFactory.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.inline.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/objArrayOop.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/symbol.hpp"
52 #include "oops/verifyOopClosure.hpp"
53 #include "prims/jvm_misc.hpp"
54 #include "prims/jvmtiExport.hpp"
55 #include "prims/jvmtiThreadState.hpp"
56 #include "prims/privilegedStack.hpp"
57 #include "runtime/arguments.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/commandLineFlagConstraintList.hpp"
61 #include "runtime/commandLineFlagWriteableList.hpp"
62 #include "runtime/commandLineFlagRangeList.hpp"
63 #include "runtime/deoptimization.hpp"
64 #include "runtime/fprofiler.hpp"
65 #include "runtime/frame.inline.hpp"
66 #include "runtime/globals.hpp"
67 #include "runtime/init.hpp"
68 #include "runtime/interfaceSupport.hpp"
69 #include "runtime/java.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniPeriodicChecker.hpp"
72 #include "runtime/timerTrace.hpp"
73 #include "runtime/memprofiler.hpp"
74 #include "runtime/mutexLocker.hpp"
75 #include "runtime/objectMonitor.hpp"
76 #include "runtime/orderAccess.inline.hpp"
77 #include "runtime/osThread.hpp"
78 #include "runtime/safepoint.hpp"
79 #include "runtime/sharedRuntime.hpp"
80 #include "runtime/statSampler.hpp"
81 #include "runtime/stubRoutines.hpp"
82 #include "runtime/sweeper.hpp"
83 #include "runtime/task.hpp"
84 #include "runtime/thread.inline.hpp"
85 #include "runtime/threadCritical.hpp"
86 #include "runtime/vframe.hpp"
87 #include "runtime/vframeArray.hpp"
88 #include "runtime/vframe_hp.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "runtime/vm_operations.hpp"
91 #include "runtime/vm_version.hpp"
92 #include "services/attachListener.hpp"
93 #include "services/management.hpp"
94 #include "services/memTracker.hpp"
95 #include "services/threadService.hpp"
96 #include "trace/traceMacros.hpp"
97 #include "trace/tracing.hpp"
98 #include "utilities/defaultStream.hpp"
99 #include "utilities/dtrace.hpp"
100 #include "utilities/events.hpp"
101 #include "utilities/macros.hpp"
102 #include "utilities/preserveException.hpp"
103 #if INCLUDE_ALL_GCS
104 #include "gc/cms/concurrentMarkSweepThread.hpp"
105 #include "gc/g1/concurrentMarkThread.inline.hpp"
106 #include "gc/parallel/pcTasks.hpp"
107 #endif // INCLUDE_ALL_GCS
108 #if INCLUDE_JVMCI
109 #include "jvmci/jvmciCompiler.hpp"
110 #include "jvmci/jvmciRuntime.hpp"
111 #endif
112 #ifdef COMPILER1
113 #include "c1/c1_Compiler.hpp"
114 #endif
115 #ifdef COMPILER2
116 #include "opto/c2compiler.hpp"
117 #include "opto/idealGraphPrinter.hpp"
118 #endif
119 #if INCLUDE_RTM_OPT
120 #include "runtime/rtmLocking.hpp"
121 #endif
122
123 // Initialization after module runtime initialization
124 void universe_post_module_init(); // must happen after call_initPhase2
125
126 #ifdef DTRACE_ENABLED
127
128 // Only bother with this argument setup if dtrace is available
129
130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
132
133 #define DTRACE_THREAD_PROBE(probe, javathread) \
134 { \
135 ResourceMark rm(this); \
136 int len = 0; \
137 const char* name = (javathread)->get_thread_name(); \
138 len = strlen(name); \
139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
140 (char *) name, len, \
141 java_lang_Thread::thread_id((javathread)->threadObj()), \
142 (uintptr_t) (javathread)->osthread()->thread_id(), \
143 java_lang_Thread::is_daemon((javathread)->threadObj())); \
144 }
145
146 #else // ndef DTRACE_ENABLED
147
148 #define DTRACE_THREAD_PROBE(probe, javathread)
149
150 #endif // ndef DTRACE_ENABLED
151
152 #ifndef USE_LIBRARY_BASED_TLS_ONLY
153 // Current thread is maintained as a thread-local variable
154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
155 #endif
156 // Class hierarchy
157 // - Thread
158 // - VMThread
159 // - WatcherThread
160 // - ConcurrentMarkSweepThread
161 // - JavaThread
162 // - CompilerThread
163
164 // ======= Thread ========
165 // Support for forcing alignment of thread objects for biased locking
166 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
167 if (UseBiasedLocking) {
168 const int alignment = markOopDesc::biased_lock_alignment;
169 size_t aligned_size = size + (alignment - sizeof(intptr_t));
170 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
171 : AllocateHeap(aligned_size, flags, CURRENT_PC,
172 AllocFailStrategy::RETURN_NULL);
173 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
174 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
175 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
176 "JavaThread alignment code overflowed allocated storage");
177 if (aligned_addr != real_malloc_addr) {
178 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
179 p2i(real_malloc_addr),
180 p2i(aligned_addr));
181 }
182 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
183 return aligned_addr;
184 } else {
185 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
186 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
187 }
188 }
189
190 void Thread::operator delete(void* p) {
191 if (UseBiasedLocking) {
192 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
193 FreeHeap(real_malloc_addr);
194 } else {
195 FreeHeap(p);
196 }
197 }
198
199
200 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
201 // JavaThread
202
203
204 Thread::Thread() {
205 // stack and get_thread
206 set_stack_base(NULL);
207 set_stack_size(0);
208 set_self_raw_id(0);
209 set_lgrp_id(-1);
210 DEBUG_ONLY(clear_suspendible_thread();)
211
212 // allocated data structures
213 set_osthread(NULL);
214 set_resource_area(new (mtThread)ResourceArea());
215 DEBUG_ONLY(_current_resource_mark = NULL;)
216 set_handle_area(new (mtThread) HandleArea(NULL));
217 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
218 set_active_handles(NULL);
219 set_free_handle_block(NULL);
220 set_last_handle_mark(NULL);
221
222 // This initial value ==> never claimed.
223 _oops_do_parity = 0;
224
225 // the handle mark links itself to last_handle_mark
226 new HandleMark(this);
227
228 // plain initialization
229 debug_only(_owned_locks = NULL;)
230 debug_only(_allow_allocation_count = 0;)
231 NOT_PRODUCT(_allow_safepoint_count = 0;)
232 NOT_PRODUCT(_skip_gcalot = false;)
233 _jvmti_env_iteration_count = 0;
234 set_allocated_bytes(0);
235 _vm_operation_started_count = 0;
236 _vm_operation_completed_count = 0;
237 _current_pending_monitor = NULL;
238 _current_pending_monitor_is_from_java = true;
239 _current_waiting_monitor = NULL;
240 _num_nested_signal = 0;
241 omFreeList = NULL;
242 omFreeCount = 0;
243 omFreeProvision = 32;
244 omInUseList = NULL;
245 omInUseCount = 0;
246
247 #ifdef ASSERT
248 _visited_for_critical_count = false;
249 #endif
250
251 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
252 Monitor::_safepoint_check_sometimes);
253 _suspend_flags = 0;
254
255 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
256 _hashStateX = os::random();
257 _hashStateY = 842502087;
258 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
259 _hashStateW = 273326509;
260
261 _OnTrap = 0;
262 _schedctl = NULL;
263 _Stalled = 0;
264 _TypeTag = 0x2BAD;
265
266 // Many of the following fields are effectively final - immutable
267 // Note that nascent threads can't use the Native Monitor-Mutex
268 // construct until the _MutexEvent is initialized ...
269 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
270 // we might instead use a stack of ParkEvents that we could provision on-demand.
271 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
272 // and ::Release()
273 _ParkEvent = ParkEvent::Allocate(this);
274 _SleepEvent = ParkEvent::Allocate(this);
275 _MutexEvent = ParkEvent::Allocate(this);
276 _MuxEvent = ParkEvent::Allocate(this);
277
278 #ifdef CHECK_UNHANDLED_OOPS
279 if (CheckUnhandledOops) {
280 _unhandled_oops = new UnhandledOops(this);
281 }
282 #endif // CHECK_UNHANDLED_OOPS
283 #ifdef ASSERT
284 if (UseBiasedLocking) {
285 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
286 assert(this == _real_malloc_address ||
287 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
288 "bug in forced alignment of thread objects");
289 }
290 #endif // ASSERT
291 }
292
293 void Thread::initialize_thread_current() {
294 #ifndef USE_LIBRARY_BASED_TLS_ONLY
295 assert(_thr_current == NULL, "Thread::current already initialized");
296 _thr_current = this;
297 #endif
298 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
299 ThreadLocalStorage::set_thread(this);
300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
301 }
302
303 void Thread::clear_thread_current() {
304 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
305 #ifndef USE_LIBRARY_BASED_TLS_ONLY
306 _thr_current = NULL;
307 #endif
308 ThreadLocalStorage::set_thread(NULL);
309 }
310
311 void Thread::record_stack_base_and_size() {
312 set_stack_base(os::current_stack_base());
313 set_stack_size(os::current_stack_size());
314 // CR 7190089: on Solaris, primordial thread's stack is adjusted
315 // in initialize_thread(). Without the adjustment, stack size is
316 // incorrect if stack is set to unlimited (ulimit -s unlimited).
317 // So far, only Solaris has real implementation of initialize_thread().
318 //
319 // set up any platform-specific state.
320 os::initialize_thread(this);
321
322 // Set stack limits after thread is initialized.
323 if (is_Java_thread()) {
324 ((JavaThread*) this)->set_stack_overflow_limit();
325 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
326 }
327 #if INCLUDE_NMT
328 // record thread's native stack, stack grows downward
329 MemTracker::record_thread_stack(stack_end(), stack_size());
330 #endif // INCLUDE_NMT
331 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
332 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
333 os::current_thread_id(), p2i(stack_base() - stack_size()),
334 p2i(stack_base()), stack_size()/1024);
335 }
336
337
338 Thread::~Thread() {
339 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
340 ObjectSynchronizer::omFlush(this);
341
342 EVENT_THREAD_DESTRUCT(this);
343
344 // stack_base can be NULL if the thread is never started or exited before
345 // record_stack_base_and_size called. Although, we would like to ensure
346 // that all started threads do call record_stack_base_and_size(), there is
347 // not proper way to enforce that.
348 #if INCLUDE_NMT
349 if (_stack_base != NULL) {
350 MemTracker::release_thread_stack(stack_end(), stack_size());
351 #ifdef ASSERT
352 set_stack_base(NULL);
353 #endif
354 }
355 #endif // INCLUDE_NMT
356
357 // deallocate data structures
358 delete resource_area();
359 // since the handle marks are using the handle area, we have to deallocated the root
360 // handle mark before deallocating the thread's handle area,
361 assert(last_handle_mark() != NULL, "check we have an element");
362 delete last_handle_mark();
363 assert(last_handle_mark() == NULL, "check we have reached the end");
364
365 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
366 // We NULL out the fields for good hygiene.
367 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
368 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
369 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
370 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
371
372 delete handle_area();
373 delete metadata_handles();
374
375 // SR_handler uses this as a termination indicator -
376 // needs to happen before os::free_thread()
377 delete _SR_lock;
378 _SR_lock = NULL;
379
380 // osthread() can be NULL, if creation of thread failed.
381 if (osthread() != NULL) os::free_thread(osthread());
382
383 // clear Thread::current if thread is deleting itself.
384 // Needed to ensure JNI correctly detects non-attached threads.
385 if (this == Thread::current()) {
386 clear_thread_current();
387 }
388
389 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
390 }
391
392 // NOTE: dummy function for assertion purpose.
393 void Thread::run() {
394 ShouldNotReachHere();
395 }
396
397 #ifdef ASSERT
398 // Private method to check for dangling thread pointer
399 void check_for_dangling_thread_pointer(Thread *thread) {
400 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
401 "possibility of dangling Thread pointer");
402 }
403 #endif
404
405 ThreadPriority Thread::get_priority(const Thread* const thread) {
406 ThreadPriority priority;
407 // Can return an error!
408 (void)os::get_priority(thread, priority);
409 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
410 return priority;
411 }
412
413 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
414 debug_only(check_for_dangling_thread_pointer(thread);)
415 // Can return an error!
416 (void)os::set_priority(thread, priority);
417 }
418
419
420 void Thread::start(Thread* thread) {
421 // Start is different from resume in that its safety is guaranteed by context or
422 // being called from a Java method synchronized on the Thread object.
423 if (!DisableStartThread) {
424 if (thread->is_Java_thread()) {
425 // Initialize the thread state to RUNNABLE before starting this thread.
426 // Can not set it after the thread started because we do not know the
427 // exact thread state at that time. It could be in MONITOR_WAIT or
428 // in SLEEPING or some other state.
429 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
430 java_lang_Thread::RUNNABLE);
431 }
432 os::start_thread(thread);
433 }
434 }
435
436 // Enqueue a VM_Operation to do the job for us - sometime later
437 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
438 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
439 VMThread::execute(vm_stop);
440 }
441
442
443 // Check if an external suspend request has completed (or has been
444 // cancelled). Returns true if the thread is externally suspended and
445 // false otherwise.
446 //
447 // The bits parameter returns information about the code path through
448 // the routine. Useful for debugging:
449 //
450 // set in is_ext_suspend_completed():
451 // 0x00000001 - routine was entered
452 // 0x00000010 - routine return false at end
453 // 0x00000100 - thread exited (return false)
454 // 0x00000200 - suspend request cancelled (return false)
455 // 0x00000400 - thread suspended (return true)
456 // 0x00001000 - thread is in a suspend equivalent state (return true)
457 // 0x00002000 - thread is native and walkable (return true)
458 // 0x00004000 - thread is native_trans and walkable (needed retry)
459 //
460 // set in wait_for_ext_suspend_completion():
461 // 0x00010000 - routine was entered
462 // 0x00020000 - suspend request cancelled before loop (return false)
463 // 0x00040000 - thread suspended before loop (return true)
464 // 0x00080000 - suspend request cancelled in loop (return false)
465 // 0x00100000 - thread suspended in loop (return true)
466 // 0x00200000 - suspend not completed during retry loop (return false)
467
468 // Helper class for tracing suspend wait debug bits.
469 //
470 // 0x00000100 indicates that the target thread exited before it could
471 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
472 // 0x00080000 each indicate a cancelled suspend request so they don't
473 // count as wait failures either.
474 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
475
476 class TraceSuspendDebugBits : public StackObj {
477 private:
478 JavaThread * jt;
479 bool is_wait;
480 bool called_by_wait; // meaningful when !is_wait
481 uint32_t * bits;
482
483 public:
484 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
485 uint32_t *_bits) {
486 jt = _jt;
487 is_wait = _is_wait;
488 called_by_wait = _called_by_wait;
489 bits = _bits;
490 }
491
492 ~TraceSuspendDebugBits() {
493 if (!is_wait) {
494 #if 1
495 // By default, don't trace bits for is_ext_suspend_completed() calls.
496 // That trace is very chatty.
497 return;
498 #else
499 if (!called_by_wait) {
500 // If tracing for is_ext_suspend_completed() is enabled, then only
501 // trace calls to it from wait_for_ext_suspend_completion()
502 return;
503 }
504 #endif
505 }
506
507 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
508 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
509 MutexLocker ml(Threads_lock); // needed for get_thread_name()
510 ResourceMark rm;
511
512 tty->print_cr(
513 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
514 jt->get_thread_name(), *bits);
515
516 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
517 }
518 }
519 }
520 };
521 #undef DEBUG_FALSE_BITS
522
523
524 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
525 uint32_t *bits) {
526 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
527
528 bool did_trans_retry = false; // only do thread_in_native_trans retry once
529 bool do_trans_retry; // flag to force the retry
530
531 *bits |= 0x00000001;
532
533 do {
534 do_trans_retry = false;
535
536 if (is_exiting()) {
537 // Thread is in the process of exiting. This is always checked
538 // first to reduce the risk of dereferencing a freed JavaThread.
539 *bits |= 0x00000100;
540 return false;
541 }
542
543 if (!is_external_suspend()) {
544 // Suspend request is cancelled. This is always checked before
545 // is_ext_suspended() to reduce the risk of a rogue resume
546 // confusing the thread that made the suspend request.
547 *bits |= 0x00000200;
548 return false;
549 }
550
551 if (is_ext_suspended()) {
552 // thread is suspended
553 *bits |= 0x00000400;
554 return true;
555 }
556
557 // Now that we no longer do hard suspends of threads running
558 // native code, the target thread can be changing thread state
559 // while we are in this routine:
560 //
561 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
562 //
563 // We save a copy of the thread state as observed at this moment
564 // and make our decision about suspend completeness based on the
565 // copy. This closes the race where the thread state is seen as
566 // _thread_in_native_trans in the if-thread_blocked check, but is
567 // seen as _thread_blocked in if-thread_in_native_trans check.
568 JavaThreadState save_state = thread_state();
569
570 if (save_state == _thread_blocked && is_suspend_equivalent()) {
571 // If the thread's state is _thread_blocked and this blocking
572 // condition is known to be equivalent to a suspend, then we can
573 // consider the thread to be externally suspended. This means that
574 // the code that sets _thread_blocked has been modified to do
575 // self-suspension if the blocking condition releases. We also
576 // used to check for CONDVAR_WAIT here, but that is now covered by
577 // the _thread_blocked with self-suspension check.
578 //
579 // Return true since we wouldn't be here unless there was still an
580 // external suspend request.
581 *bits |= 0x00001000;
582 return true;
583 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
584 // Threads running native code will self-suspend on native==>VM/Java
585 // transitions. If its stack is walkable (should always be the case
586 // unless this function is called before the actual java_suspend()
587 // call), then the wait is done.
588 *bits |= 0x00002000;
589 return true;
590 } else if (!called_by_wait && !did_trans_retry &&
591 save_state == _thread_in_native_trans &&
592 frame_anchor()->walkable()) {
593 // The thread is transitioning from thread_in_native to another
594 // thread state. check_safepoint_and_suspend_for_native_trans()
595 // will force the thread to self-suspend. If it hasn't gotten
596 // there yet we may have caught the thread in-between the native
597 // code check above and the self-suspend. Lucky us. If we were
598 // called by wait_for_ext_suspend_completion(), then it
599 // will be doing the retries so we don't have to.
600 //
601 // Since we use the saved thread state in the if-statement above,
602 // there is a chance that the thread has already transitioned to
603 // _thread_blocked by the time we get here. In that case, we will
604 // make a single unnecessary pass through the logic below. This
605 // doesn't hurt anything since we still do the trans retry.
606
607 *bits |= 0x00004000;
608
609 // Once the thread leaves thread_in_native_trans for another
610 // thread state, we break out of this retry loop. We shouldn't
611 // need this flag to prevent us from getting back here, but
612 // sometimes paranoia is good.
613 did_trans_retry = true;
614
615 // We wait for the thread to transition to a more usable state.
616 for (int i = 1; i <= SuspendRetryCount; i++) {
617 // We used to do an "os::yield_all(i)" call here with the intention
618 // that yielding would increase on each retry. However, the parameter
619 // is ignored on Linux which means the yield didn't scale up. Waiting
620 // on the SR_lock below provides a much more predictable scale up for
621 // the delay. It also provides a simple/direct point to check for any
622 // safepoint requests from the VMThread
623
624 // temporarily drops SR_lock while doing wait with safepoint check
625 // (if we're a JavaThread - the WatcherThread can also call this)
626 // and increase delay with each retry
627 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
628
629 // check the actual thread state instead of what we saved above
630 if (thread_state() != _thread_in_native_trans) {
631 // the thread has transitioned to another thread state so
632 // try all the checks (except this one) one more time.
633 do_trans_retry = true;
634 break;
635 }
636 } // end retry loop
637
638
639 }
640 } while (do_trans_retry);
641
642 *bits |= 0x00000010;
643 return false;
644 }
645
646 // Wait for an external suspend request to complete (or be cancelled).
647 // Returns true if the thread is externally suspended and false otherwise.
648 //
649 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
650 uint32_t *bits) {
651 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
652 false /* !called_by_wait */, bits);
653
654 // local flag copies to minimize SR_lock hold time
655 bool is_suspended;
656 bool pending;
657 uint32_t reset_bits;
658
659 // set a marker so is_ext_suspend_completed() knows we are the caller
660 *bits |= 0x00010000;
661
662 // We use reset_bits to reinitialize the bits value at the top of
663 // each retry loop. This allows the caller to make use of any
664 // unused bits for their own marking purposes.
665 reset_bits = *bits;
666
667 {
668 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
669 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
670 delay, bits);
671 pending = is_external_suspend();
672 }
673 // must release SR_lock to allow suspension to complete
674
675 if (!pending) {
676 // A cancelled suspend request is the only false return from
677 // is_ext_suspend_completed() that keeps us from entering the
678 // retry loop.
679 *bits |= 0x00020000;
680 return false;
681 }
682
683 if (is_suspended) {
684 *bits |= 0x00040000;
685 return true;
686 }
687
688 for (int i = 1; i <= retries; i++) {
689 *bits = reset_bits; // reinit to only track last retry
690
691 // We used to do an "os::yield_all(i)" call here with the intention
692 // that yielding would increase on each retry. However, the parameter
693 // is ignored on Linux which means the yield didn't scale up. Waiting
694 // on the SR_lock below provides a much more predictable scale up for
695 // the delay. It also provides a simple/direct point to check for any
696 // safepoint requests from the VMThread
697
698 {
699 MutexLocker ml(SR_lock());
700 // wait with safepoint check (if we're a JavaThread - the WatcherThread
701 // can also call this) and increase delay with each retry
702 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
703
704 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
705 delay, bits);
706
707 // It is possible for the external suspend request to be cancelled
708 // (by a resume) before the actual suspend operation is completed.
709 // Refresh our local copy to see if we still need to wait.
710 pending = is_external_suspend();
711 }
712
713 if (!pending) {
714 // A cancelled suspend request is the only false return from
715 // is_ext_suspend_completed() that keeps us from staying in the
716 // retry loop.
717 *bits |= 0x00080000;
718 return false;
719 }
720
721 if (is_suspended) {
722 *bits |= 0x00100000;
723 return true;
724 }
725 } // end retry loop
726
727 // thread did not suspend after all our retries
728 *bits |= 0x00200000;
729 return false;
730 }
731
732 #ifndef PRODUCT
733 void JavaThread::record_jump(address target, address instr, const char* file,
734 int line) {
735
736 // This should not need to be atomic as the only way for simultaneous
737 // updates is via interrupts. Even then this should be rare or non-existent
738 // and we don't care that much anyway.
739
740 int index = _jmp_ring_index;
741 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
742 _jmp_ring[index]._target = (intptr_t) target;
743 _jmp_ring[index]._instruction = (intptr_t) instr;
744 _jmp_ring[index]._file = file;
745 _jmp_ring[index]._line = line;
746 }
747 #endif // PRODUCT
748
749 // Called by flat profiler
750 // Callers have already called wait_for_ext_suspend_completion
751 // The assertion for that is currently too complex to put here:
752 bool JavaThread::profile_last_Java_frame(frame* _fr) {
753 bool gotframe = false;
754 // self suspension saves needed state.
755 if (has_last_Java_frame() && _anchor.walkable()) {
756 *_fr = pd_last_frame();
757 gotframe = true;
758 }
759 return gotframe;
760 }
761
762 void Thread::interrupt(Thread* thread) {
763 debug_only(check_for_dangling_thread_pointer(thread);)
764 os::interrupt(thread);
765 }
766
767 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
768 debug_only(check_for_dangling_thread_pointer(thread);)
769 // Note: If clear_interrupted==false, this simply fetches and
770 // returns the value of the field osthread()->interrupted().
771 return os::is_interrupted(thread, clear_interrupted);
772 }
773
774
775 // GC Support
776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
777 jint thread_parity = _oops_do_parity;
778 if (thread_parity != strong_roots_parity) {
779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
780 if (res == thread_parity) {
781 return true;
782 } else {
783 guarantee(res == strong_roots_parity, "Or else what?");
784 return false;
785 }
786 }
787 return false;
788 }
789
790 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
791 active_handles()->oops_do(f);
792 // Do oop for ThreadShadow
793 f->do_oop((oop*)&_pending_exception);
794 handle_area()->oops_do(f);
795 }
796
797 void Thread::metadata_handles_do(void f(Metadata*)) {
798 // Only walk the Handles in Thread.
799 if (metadata_handles() != NULL) {
800 for (int i = 0; i< metadata_handles()->length(); i++) {
801 f(metadata_handles()->at(i));
802 }
803 }
804 }
805
806 void Thread::print_on(outputStream* st) const {
807 // get_priority assumes osthread initialized
808 if (osthread() != NULL) {
809 int os_prio;
810 if (os::get_native_priority(this, &os_prio) == OS_OK) {
811 st->print("os_prio=%d ", os_prio);
812 }
813 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
814 ext().print_on(st);
815 osthread()->print_on(st);
816 }
817 debug_only(if (WizardMode) print_owned_locks_on(st);)
818 }
819
820 // Thread::print_on_error() is called by fatal error handler. Don't use
821 // any lock or allocate memory.
822 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
823 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
824
825 if (is_VM_thread()) { st->print("VMThread"); }
826 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
827 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
828 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
829 else { st->print("Thread"); }
830
831 if (is_Named_thread()) {
832 st->print(" \"%s\"", name());
833 }
834
835 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
836 p2i(stack_end()), p2i(stack_base()));
837
838 if (osthread()) {
839 st->print(" [id=%d]", osthread()->thread_id());
840 }
841 }
842
843 void JavaThread::print_vt_buffer_stats_on(outputStream* st) const {
844 st->print_cr("%s:", this->name());
845 st->print_cr("\tChunks in use : %d", vtchunk_in_use());
846 st->print_cr("\tCached chunk : %d", local_free_chunk() == NULL ? 0 : 1);
847 st->print_cr("\tMax chunks : %d", vtchunk_max());
848 st->print_cr("\tReturned chunks: %d", vtchunk_total_returned());
849 st->print_cr("\tMemory buffered: %ld", vtchunk_total_memory_buffered());
850 st->print_cr("");
851 }
852
853 #ifdef ASSERT
854 void Thread::print_owned_locks_on(outputStream* st) const {
855 Monitor *cur = _owned_locks;
856 if (cur == NULL) {
857 st->print(" (no locks) ");
858 } else {
859 st->print_cr(" Locks owned:");
860 while (cur) {
861 cur->print_on(st);
862 cur = cur->next();
863 }
864 }
865 }
866
867 static int ref_use_count = 0;
868
869 bool Thread::owns_locks_but_compiled_lock() const {
870 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
871 if (cur != Compile_lock) return true;
872 }
873 return false;
874 }
875
876
877 #endif
878
879 #ifndef PRODUCT
880
881 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
882 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
883 // no threads which allow_vm_block's are held
884 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
885 // Check if current thread is allowed to block at a safepoint
886 if (!(_allow_safepoint_count == 0)) {
887 fatal("Possible safepoint reached by thread that does not allow it");
888 }
889 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
890 fatal("LEAF method calling lock?");
891 }
892
893 #ifdef ASSERT
894 if (potential_vm_operation && is_Java_thread()
895 && !Universe::is_bootstrapping()) {
896 // Make sure we do not hold any locks that the VM thread also uses.
897 // This could potentially lead to deadlocks
898 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
899 // Threads_lock is special, since the safepoint synchronization will not start before this is
900 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
901 // since it is used to transfer control between JavaThreads and the VMThread
902 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
903 if ((cur->allow_vm_block() &&
904 cur != Threads_lock &&
905 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
906 cur != VMOperationRequest_lock &&
907 cur != VMOperationQueue_lock) ||
908 cur->rank() == Mutex::special) {
909 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
910 }
911 }
912 }
913
914 if (GCALotAtAllSafepoints) {
915 // We could enter a safepoint here and thus have a gc
916 InterfaceSupport::check_gc_alot();
917 }
918 #endif
919 }
920 #endif
921
922 bool Thread::is_in_stack(address adr) const {
923 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
924 address end = os::current_stack_pointer();
925 // Allow non Java threads to call this without stack_base
926 if (_stack_base == NULL) return true;
927 if (stack_base() >= adr && adr >= end) return true;
928
929 return false;
930 }
931
932 bool Thread::is_in_usable_stack(address adr) const {
933 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
934 size_t usable_stack_size = _stack_size - stack_guard_size;
935
936 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
937 }
938
939
940 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
941 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
942 // used for compilation in the future. If that change is made, the need for these methods
943 // should be revisited, and they should be removed if possible.
944
945 bool Thread::is_lock_owned(address adr) const {
946 return on_local_stack(adr);
947 }
948
949 bool Thread::set_as_starting_thread() {
950 // NOTE: this must be called inside the main thread.
951 return os::create_main_thread((JavaThread*)this);
952 }
953
954 static void initialize_class(Symbol* class_name, TRAPS) {
955 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
956 InstanceKlass::cast(klass)->initialize(CHECK);
957 }
958
959
960 // Creates the initial ThreadGroup
961 static Handle create_initial_thread_group(TRAPS) {
962 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
963 InstanceKlass* ik = InstanceKlass::cast(k);
964
965 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
966 {
967 JavaValue result(T_VOID);
968 JavaCalls::call_special(&result,
969 system_instance,
970 ik,
971 vmSymbols::object_initializer_name(),
972 vmSymbols::void_method_signature(),
973 CHECK_NH);
974 }
975 Universe::set_system_thread_group(system_instance());
976
977 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
978 {
979 JavaValue result(T_VOID);
980 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
981 JavaCalls::call_special(&result,
982 main_instance,
983 ik,
984 vmSymbols::object_initializer_name(),
985 vmSymbols::threadgroup_string_void_signature(),
986 system_instance,
987 string,
988 CHECK_NH);
989 }
990 return main_instance;
991 }
992
993 // Creates the initial Thread
994 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
995 TRAPS) {
996 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
997 InstanceKlass* ik = InstanceKlass::cast(k);
998 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
999
1000 java_lang_Thread::set_thread(thread_oop(), thread);
1001 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1002 thread->set_threadObj(thread_oop());
1003
1004 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1005
1006 JavaValue result(T_VOID);
1007 JavaCalls::call_special(&result, thread_oop,
1008 ik,
1009 vmSymbols::object_initializer_name(),
1010 vmSymbols::threadgroup_string_void_signature(),
1011 thread_group,
1012 string,
1013 CHECK_NULL);
1014 return thread_oop();
1015 }
1016
1017 char java_runtime_name[128] = "";
1018 char java_runtime_version[128] = "";
1019
1020 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1021 static const char* get_java_runtime_name(TRAPS) {
1022 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1023 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1024 fieldDescriptor fd;
1025 bool found = k != NULL &&
1026 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1027 vmSymbols::string_signature(), &fd);
1028 if (found) {
1029 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1030 if (name_oop == NULL) {
1031 return NULL;
1032 }
1033 const char* name = java_lang_String::as_utf8_string(name_oop,
1034 java_runtime_name,
1035 sizeof(java_runtime_name));
1036 return name;
1037 } else {
1038 return NULL;
1039 }
1040 }
1041
1042 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1043 static const char* get_java_runtime_version(TRAPS) {
1044 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1045 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1046 fieldDescriptor fd;
1047 bool found = k != NULL &&
1048 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1049 vmSymbols::string_signature(), &fd);
1050 if (found) {
1051 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1052 if (name_oop == NULL) {
1053 return NULL;
1054 }
1055 const char* name = java_lang_String::as_utf8_string(name_oop,
1056 java_runtime_version,
1057 sizeof(java_runtime_version));
1058 return name;
1059 } else {
1060 return NULL;
1061 }
1062 }
1063
1064 // General purpose hook into Java code, run once when the VM is initialized.
1065 // The Java library method itself may be changed independently from the VM.
1066 static void call_postVMInitHook(TRAPS) {
1067 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1068 if (klass != NULL) {
1069 JavaValue result(T_VOID);
1070 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1071 vmSymbols::void_method_signature(),
1072 CHECK);
1073 }
1074 }
1075
1076 static void reset_vm_info_property(TRAPS) {
1077 // the vm info string
1078 ResourceMark rm(THREAD);
1079 const char *vm_info = VM_Version::vm_info_string();
1080
1081 // java.lang.System class
1082 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1083
1084 // setProperty arguments
1085 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1086 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1087
1088 // return value
1089 JavaValue r(T_OBJECT);
1090
1091 // public static String setProperty(String key, String value);
1092 JavaCalls::call_static(&r,
1093 klass,
1094 vmSymbols::setProperty_name(),
1095 vmSymbols::string_string_string_signature(),
1096 key_str,
1097 value_str,
1098 CHECK);
1099 }
1100
1101
1102 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1103 bool daemon, TRAPS) {
1104 assert(thread_group.not_null(), "thread group should be specified");
1105 assert(threadObj() == NULL, "should only create Java thread object once");
1106
1107 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1108 InstanceKlass* ik = InstanceKlass::cast(k);
1109 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1110
1111 java_lang_Thread::set_thread(thread_oop(), this);
1112 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1113 set_threadObj(thread_oop());
1114
1115 JavaValue result(T_VOID);
1116 if (thread_name != NULL) {
1117 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1118 // Thread gets assigned specified name and null target
1119 JavaCalls::call_special(&result,
1120 thread_oop,
1121 ik,
1122 vmSymbols::object_initializer_name(),
1123 vmSymbols::threadgroup_string_void_signature(),
1124 thread_group, // Argument 1
1125 name, // Argument 2
1126 THREAD);
1127 } else {
1128 // Thread gets assigned name "Thread-nnn" and null target
1129 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1130 JavaCalls::call_special(&result,
1131 thread_oop,
1132 ik,
1133 vmSymbols::object_initializer_name(),
1134 vmSymbols::threadgroup_runnable_void_signature(),
1135 thread_group, // Argument 1
1136 Handle(), // Argument 2
1137 THREAD);
1138 }
1139
1140
1141 if (daemon) {
1142 java_lang_Thread::set_daemon(thread_oop());
1143 }
1144
1145 if (HAS_PENDING_EXCEPTION) {
1146 return;
1147 }
1148
1149 Klass* group = SystemDictionary::ThreadGroup_klass();
1150 Handle threadObj(THREAD, this->threadObj());
1151
1152 JavaCalls::call_special(&result,
1153 thread_group,
1154 group,
1155 vmSymbols::add_method_name(),
1156 vmSymbols::thread_void_signature(),
1157 threadObj, // Arg 1
1158 THREAD);
1159 }
1160
1161 // NamedThread -- non-JavaThread subclasses with multiple
1162 // uniquely named instances should derive from this.
1163 NamedThread::NamedThread() : Thread() {
1164 _name = NULL;
1165 _processed_thread = NULL;
1166 _gc_id = GCId::undefined();
1167 }
1168
1169 NamedThread::~NamedThread() {
1170 if (_name != NULL) {
1171 FREE_C_HEAP_ARRAY(char, _name);
1172 _name = NULL;
1173 }
1174 }
1175
1176 void NamedThread::set_name(const char* format, ...) {
1177 guarantee(_name == NULL, "Only get to set name once.");
1178 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1179 guarantee(_name != NULL, "alloc failure");
1180 va_list ap;
1181 va_start(ap, format);
1182 jio_vsnprintf(_name, max_name_len, format, ap);
1183 va_end(ap);
1184 }
1185
1186 void NamedThread::initialize_named_thread() {
1187 set_native_thread_name(name());
1188 }
1189
1190 void NamedThread::print_on(outputStream* st) const {
1191 st->print("\"%s\" ", name());
1192 Thread::print_on(st);
1193 st->cr();
1194 }
1195
1196
1197 // ======= WatcherThread ========
1198
1199 // The watcher thread exists to simulate timer interrupts. It should
1200 // be replaced by an abstraction over whatever native support for
1201 // timer interrupts exists on the platform.
1202
1203 WatcherThread* WatcherThread::_watcher_thread = NULL;
1204 bool WatcherThread::_startable = false;
1205 volatile bool WatcherThread::_should_terminate = false;
1206
1207 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1208 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1209 if (os::create_thread(this, os::watcher_thread)) {
1210 _watcher_thread = this;
1211
1212 // Set the watcher thread to the highest OS priority which should not be
1213 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1214 // is created. The only normal thread using this priority is the reference
1215 // handler thread, which runs for very short intervals only.
1216 // If the VMThread's priority is not lower than the WatcherThread profiling
1217 // will be inaccurate.
1218 os::set_priority(this, MaxPriority);
1219 if (!DisableStartThread) {
1220 os::start_thread(this);
1221 }
1222 }
1223 }
1224
1225 int WatcherThread::sleep() const {
1226 // The WatcherThread does not participate in the safepoint protocol
1227 // for the PeriodicTask_lock because it is not a JavaThread.
1228 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1229
1230 if (_should_terminate) {
1231 // check for termination before we do any housekeeping or wait
1232 return 0; // we did not sleep.
1233 }
1234
1235 // remaining will be zero if there are no tasks,
1236 // causing the WatcherThread to sleep until a task is
1237 // enrolled
1238 int remaining = PeriodicTask::time_to_wait();
1239 int time_slept = 0;
1240
1241 // we expect this to timeout - we only ever get unparked when
1242 // we should terminate or when a new task has been enrolled
1243 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1244
1245 jlong time_before_loop = os::javaTimeNanos();
1246
1247 while (true) {
1248 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1249 remaining);
1250 jlong now = os::javaTimeNanos();
1251
1252 if (remaining == 0) {
1253 // if we didn't have any tasks we could have waited for a long time
1254 // consider the time_slept zero and reset time_before_loop
1255 time_slept = 0;
1256 time_before_loop = now;
1257 } else {
1258 // need to recalculate since we might have new tasks in _tasks
1259 time_slept = (int) ((now - time_before_loop) / 1000000);
1260 }
1261
1262 // Change to task list or spurious wakeup of some kind
1263 if (timedout || _should_terminate) {
1264 break;
1265 }
1266
1267 remaining = PeriodicTask::time_to_wait();
1268 if (remaining == 0) {
1269 // Last task was just disenrolled so loop around and wait until
1270 // another task gets enrolled
1271 continue;
1272 }
1273
1274 remaining -= time_slept;
1275 if (remaining <= 0) {
1276 break;
1277 }
1278 }
1279
1280 return time_slept;
1281 }
1282
1283 void WatcherThread::run() {
1284 assert(this == watcher_thread(), "just checking");
1285
1286 this->record_stack_base_and_size();
1287 this->set_native_thread_name(this->name());
1288 this->set_active_handles(JNIHandleBlock::allocate_block());
1289 while (true) {
1290 assert(watcher_thread() == Thread::current(), "thread consistency check");
1291 assert(watcher_thread() == this, "thread consistency check");
1292
1293 // Calculate how long it'll be until the next PeriodicTask work
1294 // should be done, and sleep that amount of time.
1295 int time_waited = sleep();
1296
1297 if (is_error_reported()) {
1298 // A fatal error has happened, the error handler(VMError::report_and_die)
1299 // should abort JVM after creating an error log file. However in some
1300 // rare cases, the error handler itself might deadlock. Here periodically
1301 // check for error reporting timeouts, and if it happens, just proceed to
1302 // abort the VM.
1303
1304 // This code is in WatcherThread because WatcherThread wakes up
1305 // periodically so the fatal error handler doesn't need to do anything;
1306 // also because the WatcherThread is less likely to crash than other
1307 // threads.
1308
1309 for (;;) {
1310 // Note: we use naked sleep in this loop because we want to avoid using
1311 // any kind of VM infrastructure which may be broken at this point.
1312 if (VMError::check_timeout()) {
1313 // We hit error reporting timeout. Error reporting was interrupted and
1314 // will be wrapping things up now (closing files etc). Give it some more
1315 // time, then quit the VM.
1316 os::naked_short_sleep(200);
1317 // Print a message to stderr.
1318 fdStream err(defaultStream::output_fd());
1319 err.print_raw_cr("# [ timer expired, abort... ]");
1320 // skip atexit/vm_exit/vm_abort hooks
1321 os::die();
1322 }
1323
1324 // Wait a second, then recheck for timeout.
1325 os::naked_short_sleep(999);
1326 }
1327 }
1328
1329 if (_should_terminate) {
1330 // check for termination before posting the next tick
1331 break;
1332 }
1333
1334 PeriodicTask::real_time_tick(time_waited);
1335 }
1336
1337 // Signal that it is terminated
1338 {
1339 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1340 _watcher_thread = NULL;
1341 Terminator_lock->notify();
1342 }
1343 }
1344
1345 void WatcherThread::start() {
1346 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1347
1348 if (watcher_thread() == NULL && _startable) {
1349 _should_terminate = false;
1350 // Create the single instance of WatcherThread
1351 new WatcherThread();
1352 }
1353 }
1354
1355 void WatcherThread::make_startable() {
1356 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1357 _startable = true;
1358 }
1359
1360 void WatcherThread::stop() {
1361 {
1362 // Follow normal safepoint aware lock enter protocol since the
1363 // WatcherThread is stopped by another JavaThread.
1364 MutexLocker ml(PeriodicTask_lock);
1365 _should_terminate = true;
1366
1367 WatcherThread* watcher = watcher_thread();
1368 if (watcher != NULL) {
1369 // unpark the WatcherThread so it can see that it should terminate
1370 watcher->unpark();
1371 }
1372 }
1373
1374 MutexLocker mu(Terminator_lock);
1375
1376 while (watcher_thread() != NULL) {
1377 // This wait should make safepoint checks, wait without a timeout,
1378 // and wait as a suspend-equivalent condition.
1379 //
1380 // Note: If the FlatProfiler is running, then this thread is waiting
1381 // for the WatcherThread to terminate and the WatcherThread, via the
1382 // FlatProfiler task, is waiting for the external suspend request on
1383 // this thread to complete. wait_for_ext_suspend_completion() will
1384 // eventually timeout, but that takes time. Making this wait a
1385 // suspend-equivalent condition solves that timeout problem.
1386 //
1387 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1388 Mutex::_as_suspend_equivalent_flag);
1389 }
1390 }
1391
1392 void WatcherThread::unpark() {
1393 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1394 PeriodicTask_lock->notify();
1395 }
1396
1397 void WatcherThread::print_on(outputStream* st) const {
1398 st->print("\"%s\" ", name());
1399 Thread::print_on(st);
1400 st->cr();
1401 }
1402
1403 // ======= JavaThread ========
1404
1405 #if INCLUDE_JVMCI
1406
1407 jlong* JavaThread::_jvmci_old_thread_counters;
1408
1409 bool jvmci_counters_include(JavaThread* thread) {
1410 oop threadObj = thread->threadObj();
1411 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1412 }
1413
1414 void JavaThread::collect_counters(typeArrayOop array) {
1415 if (JVMCICounterSize > 0) {
1416 MutexLocker tl(Threads_lock);
1417 for (int i = 0; i < array->length(); i++) {
1418 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1419 }
1420 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1421 if (jvmci_counters_include(tp)) {
1422 for (int i = 0; i < array->length(); i++) {
1423 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1424 }
1425 }
1426 }
1427 }
1428 }
1429
1430 #endif // INCLUDE_JVMCI
1431
1432 // A JavaThread is a normal Java thread
1433
1434 void JavaThread::initialize() {
1435 // Initialize fields
1436
1437 set_saved_exception_pc(NULL);
1438 set_threadObj(NULL);
1439 _anchor.clear();
1440 set_entry_point(NULL);
1441 set_jni_functions(jni_functions());
1442 set_callee_target(NULL);
1443 set_vm_result(NULL);
1444 set_vm_result_2(NULL);
1445 set_vframe_array_head(NULL);
1446 set_vframe_array_last(NULL);
1447 set_deferred_locals(NULL);
1448 set_deopt_mark(NULL);
1449 set_deopt_compiled_method(NULL);
1450 clear_must_deopt_id();
1451 set_monitor_chunks(NULL);
1452 set_next(NULL);
1453 set_thread_state(_thread_new);
1454 _terminated = _not_terminated;
1455 _privileged_stack_top = NULL;
1456 _array_for_gc = NULL;
1457 _suspend_equivalent = false;
1458 _in_deopt_handler = 0;
1459 _doing_unsafe_access = false;
1460 _stack_guard_state = stack_guard_unused;
1461 #if INCLUDE_JVMCI
1462 _pending_monitorenter = false;
1463 _pending_deoptimization = -1;
1464 _pending_failed_speculation = NULL;
1465 _pending_transfer_to_interpreter = false;
1466 _adjusting_comp_level = false;
1467 _jvmci._alternate_call_target = NULL;
1468 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1469 if (JVMCICounterSize > 0) {
1470 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1471 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1472 } else {
1473 _jvmci_counters = NULL;
1474 }
1475 #endif // INCLUDE_JVMCI
1476 _reserved_stack_activation = NULL; // stack base not known yet
1477 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1478 _exception_pc = 0;
1479 _exception_handler_pc = 0;
1480 _is_method_handle_return = 0;
1481 _jvmti_thread_state= NULL;
1482 _should_post_on_exceptions_flag = JNI_FALSE;
1483 _jvmti_get_loaded_classes_closure = NULL;
1484 _interp_only_mode = 0;
1485 _special_runtime_exit_condition = _no_async_condition;
1486 _pending_async_exception = NULL;
1487 _thread_stat = NULL;
1488 _thread_stat = new ThreadStatistics();
1489 _blocked_on_compilation = false;
1490 _jni_active_critical = 0;
1491 _pending_jni_exception_check_fn = NULL;
1492 _do_not_unlock_if_synchronized = false;
1493 _cached_monitor_info = NULL;
1494 _parker = Parker::Allocate(this);
1495
1496 #ifndef PRODUCT
1497 _jmp_ring_index = 0;
1498 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1499 record_jump(NULL, NULL, NULL, 0);
1500 }
1501 #endif // PRODUCT
1502
1503 set_thread_profiler(NULL);
1504 if (FlatProfiler::is_active()) {
1505 // This is where we would decide to either give each thread it's own profiler
1506 // or use one global one from FlatProfiler,
1507 // or up to some count of the number of profiled threads, etc.
1508 ThreadProfiler* pp = new ThreadProfiler();
1509 pp->engage();
1510 set_thread_profiler(pp);
1511 }
1512
1513 // Setup safepoint state info for this thread
1514 ThreadSafepointState::create(this);
1515
1516 debug_only(_java_call_counter = 0);
1517
1518 // JVMTI PopFrame support
1519 _popframe_condition = popframe_inactive;
1520 _popframe_preserved_args = NULL;
1521 _popframe_preserved_args_size = 0;
1522 _frames_to_pop_failed_realloc = 0;
1523
1524 // Buffered value types support
1525 _vt_alloc_ptr = NULL;
1526 _vt_alloc_limit = NULL;
1527 _local_free_chunk = NULL;
1528 // Buffered value types instrumentation support
1529 _vtchunk_in_use = 0;
1530 _vtchunk_max = 0;
1531 _vtchunk_total_returned = 0;
1532 _vtchunk_total_memory_buffered = 0;
1533
1534 pd_initialize();
1535 }
1536
1537 #if INCLUDE_ALL_GCS
1538 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1539 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1540 #endif // INCLUDE_ALL_GCS
1541
1542 JavaThread::JavaThread(bool is_attaching_via_jni) :
1543 Thread()
1544 #if INCLUDE_ALL_GCS
1545 , _satb_mark_queue(&_satb_mark_queue_set),
1546 _dirty_card_queue(&_dirty_card_queue_set)
1547 #endif // INCLUDE_ALL_GCS
1548 {
1549 initialize();
1550 if (is_attaching_via_jni) {
1551 _jni_attach_state = _attaching_via_jni;
1552 } else {
1553 _jni_attach_state = _not_attaching_via_jni;
1554 }
1555 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1556 }
1557
1558 bool JavaThread::reguard_stack(address cur_sp) {
1559 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1560 && _stack_guard_state != stack_guard_reserved_disabled) {
1561 return true; // Stack already guarded or guard pages not needed.
1562 }
1563
1564 if (register_stack_overflow()) {
1565 // For those architectures which have separate register and
1566 // memory stacks, we must check the register stack to see if
1567 // it has overflowed.
1568 return false;
1569 }
1570
1571 // Java code never executes within the yellow zone: the latter is only
1572 // there to provoke an exception during stack banging. If java code
1573 // is executing there, either StackShadowPages should be larger, or
1574 // some exception code in c1, c2 or the interpreter isn't unwinding
1575 // when it should.
1576 guarantee(cur_sp > stack_reserved_zone_base(),
1577 "not enough space to reguard - increase StackShadowPages");
1578 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1579 enable_stack_yellow_reserved_zone();
1580 if (reserved_stack_activation() != stack_base()) {
1581 set_reserved_stack_activation(stack_base());
1582 }
1583 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1584 set_reserved_stack_activation(stack_base());
1585 enable_stack_reserved_zone();
1586 }
1587 return true;
1588 }
1589
1590 bool JavaThread::reguard_stack(void) {
1591 return reguard_stack(os::current_stack_pointer());
1592 }
1593
1594
1595 void JavaThread::block_if_vm_exited() {
1596 if (_terminated == _vm_exited) {
1597 // _vm_exited is set at safepoint, and Threads_lock is never released
1598 // we will block here forever
1599 Threads_lock->lock_without_safepoint_check();
1600 ShouldNotReachHere();
1601 }
1602 }
1603
1604
1605 // Remove this ifdef when C1 is ported to the compiler interface.
1606 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1607 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1608
1609 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1610 Thread()
1611 #if INCLUDE_ALL_GCS
1612 , _satb_mark_queue(&_satb_mark_queue_set),
1613 _dirty_card_queue(&_dirty_card_queue_set)
1614 #endif // INCLUDE_ALL_GCS
1615 {
1616 initialize();
1617 _jni_attach_state = _not_attaching_via_jni;
1618 set_entry_point(entry_point);
1619 // Create the native thread itself.
1620 // %note runtime_23
1621 os::ThreadType thr_type = os::java_thread;
1622 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1623 os::java_thread;
1624 os::create_thread(this, thr_type, stack_sz);
1625 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1626 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1627 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1628 // the exception consists of creating the exception object & initializing it, initialization
1629 // will leave the VM via a JavaCall and then all locks must be unlocked).
1630 //
1631 // The thread is still suspended when we reach here. Thread must be explicit started
1632 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1633 // by calling Threads:add. The reason why this is not done here, is because the thread
1634 // object must be fully initialized (take a look at JVM_Start)
1635 }
1636
1637 JavaThread::~JavaThread() {
1638
1639 // JSR166 -- return the parker to the free list
1640 Parker::Release(_parker);
1641 _parker = NULL;
1642
1643 // Free any remaining previous UnrollBlock
1644 vframeArray* old_array = vframe_array_last();
1645
1646 if (old_array != NULL) {
1647 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1648 old_array->set_unroll_block(NULL);
1649 delete old_info;
1650 delete old_array;
1651 }
1652
1653 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1654 if (deferred != NULL) {
1655 // This can only happen if thread is destroyed before deoptimization occurs.
1656 assert(deferred->length() != 0, "empty array!");
1657 do {
1658 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1659 deferred->remove_at(0);
1660 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1661 delete dlv;
1662 } while (deferred->length() != 0);
1663 delete deferred;
1664 }
1665
1666 // All Java related clean up happens in exit
1667 ThreadSafepointState::destroy(this);
1668 if (_thread_profiler != NULL) delete _thread_profiler;
1669 if (_thread_stat != NULL) delete _thread_stat;
1670
1671 #if INCLUDE_JVMCI
1672 if (JVMCICounterSize > 0) {
1673 if (jvmci_counters_include(this)) {
1674 for (int i = 0; i < JVMCICounterSize; i++) {
1675 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1676 }
1677 }
1678 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1679 }
1680 #endif // INCLUDE_JVMCI
1681 }
1682
1683
1684 // The first routine called by a new Java thread
1685 void JavaThread::run() {
1686 // initialize thread-local alloc buffer related fields
1687 this->initialize_tlab();
1688
1689 // used to test validity of stack trace backs
1690 this->record_base_of_stack_pointer();
1691
1692 // Record real stack base and size.
1693 this->record_stack_base_and_size();
1694
1695 this->create_stack_guard_pages();
1696
1697 this->cache_global_variables();
1698
1699 // Thread is now sufficient initialized to be handled by the safepoint code as being
1700 // in the VM. Change thread state from _thread_new to _thread_in_vm
1701 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1702
1703 assert(JavaThread::current() == this, "sanity check");
1704 assert(!Thread::current()->owns_locks(), "sanity check");
1705
1706 DTRACE_THREAD_PROBE(start, this);
1707
1708 // This operation might block. We call that after all safepoint checks for a new thread has
1709 // been completed.
1710 this->set_active_handles(JNIHandleBlock::allocate_block());
1711
1712 if (JvmtiExport::should_post_thread_life()) {
1713 JvmtiExport::post_thread_start(this);
1714 }
1715
1716 EventThreadStart event;
1717 if (event.should_commit()) {
1718 event.set_thread(THREAD_TRACE_ID(this));
1719 event.commit();
1720 }
1721
1722 // We call another function to do the rest so we are sure that the stack addresses used
1723 // from there will be lower than the stack base just computed
1724 thread_main_inner();
1725
1726 // Note, thread is no longer valid at this point!
1727 }
1728
1729
1730 void JavaThread::thread_main_inner() {
1731 assert(JavaThread::current() == this, "sanity check");
1732 assert(this->threadObj() != NULL, "just checking");
1733
1734 // Execute thread entry point unless this thread has a pending exception
1735 // or has been stopped before starting.
1736 // Note: Due to JVM_StopThread we can have pending exceptions already!
1737 if (!this->has_pending_exception() &&
1738 !java_lang_Thread::is_stillborn(this->threadObj())) {
1739 {
1740 ResourceMark rm(this);
1741 this->set_native_thread_name(this->get_thread_name());
1742 }
1743 HandleMark hm(this);
1744 this->entry_point()(this, this);
1745 }
1746
1747 DTRACE_THREAD_PROBE(stop, this);
1748
1749 this->exit(false);
1750 delete this;
1751 }
1752
1753
1754 static void ensure_join(JavaThread* thread) {
1755 // We do not need to grap the Threads_lock, since we are operating on ourself.
1756 Handle threadObj(thread, thread->threadObj());
1757 assert(threadObj.not_null(), "java thread object must exist");
1758 ObjectLocker lock(threadObj, thread);
1759 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1760 thread->clear_pending_exception();
1761 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1762 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1763 // Clear the native thread instance - this makes isAlive return false and allows the join()
1764 // to complete once we've done the notify_all below
1765 java_lang_Thread::set_thread(threadObj(), NULL);
1766 lock.notify_all(thread);
1767 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1768 thread->clear_pending_exception();
1769 }
1770
1771
1772 // For any new cleanup additions, please check to see if they need to be applied to
1773 // cleanup_failed_attach_current_thread as well.
1774 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1775 assert(this == JavaThread::current(), "thread consistency check");
1776
1777 HandleMark hm(this);
1778 Handle uncaught_exception(this, this->pending_exception());
1779 this->clear_pending_exception();
1780 Handle threadObj(this, this->threadObj());
1781 assert(threadObj.not_null(), "Java thread object should be created");
1782
1783 if (get_thread_profiler() != NULL) {
1784 get_thread_profiler()->disengage();
1785 ResourceMark rm;
1786 get_thread_profiler()->print(get_thread_name());
1787 }
1788
1789
1790 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1791 {
1792 EXCEPTION_MARK;
1793
1794 CLEAR_PENDING_EXCEPTION;
1795 }
1796 if (!destroy_vm) {
1797 if (uncaught_exception.not_null()) {
1798 EXCEPTION_MARK;
1799 // Call method Thread.dispatchUncaughtException().
1800 Klass* thread_klass = SystemDictionary::Thread_klass();
1801 JavaValue result(T_VOID);
1802 JavaCalls::call_virtual(&result,
1803 threadObj, thread_klass,
1804 vmSymbols::dispatchUncaughtException_name(),
1805 vmSymbols::throwable_void_signature(),
1806 uncaught_exception,
1807 THREAD);
1808 if (HAS_PENDING_EXCEPTION) {
1809 ResourceMark rm(this);
1810 jio_fprintf(defaultStream::error_stream(),
1811 "\nException: %s thrown from the UncaughtExceptionHandler"
1812 " in thread \"%s\"\n",
1813 pending_exception()->klass()->external_name(),
1814 get_thread_name());
1815 CLEAR_PENDING_EXCEPTION;
1816 }
1817 }
1818
1819 // Called before the java thread exit since we want to read info
1820 // from java_lang_Thread object
1821 EventThreadEnd event;
1822 if (event.should_commit()) {
1823 event.set_thread(THREAD_TRACE_ID(this));
1824 event.commit();
1825 }
1826
1827 // Call after last event on thread
1828 EVENT_THREAD_EXIT(this);
1829
1830 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1831 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1832 // is deprecated anyhow.
1833 if (!is_Compiler_thread()) {
1834 int count = 3;
1835 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1836 EXCEPTION_MARK;
1837 JavaValue result(T_VOID);
1838 Klass* thread_klass = SystemDictionary::Thread_klass();
1839 JavaCalls::call_virtual(&result,
1840 threadObj, thread_klass,
1841 vmSymbols::exit_method_name(),
1842 vmSymbols::void_method_signature(),
1843 THREAD);
1844 CLEAR_PENDING_EXCEPTION;
1845 }
1846 }
1847 // notify JVMTI
1848 if (JvmtiExport::should_post_thread_life()) {
1849 JvmtiExport::post_thread_end(this);
1850 }
1851
1852 // We have notified the agents that we are exiting, before we go on,
1853 // we must check for a pending external suspend request and honor it
1854 // in order to not surprise the thread that made the suspend request.
1855 while (true) {
1856 {
1857 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1858 if (!is_external_suspend()) {
1859 set_terminated(_thread_exiting);
1860 ThreadService::current_thread_exiting(this);
1861 break;
1862 }
1863 // Implied else:
1864 // Things get a little tricky here. We have a pending external
1865 // suspend request, but we are holding the SR_lock so we
1866 // can't just self-suspend. So we temporarily drop the lock
1867 // and then self-suspend.
1868 }
1869
1870 ThreadBlockInVM tbivm(this);
1871 java_suspend_self();
1872
1873 // We're done with this suspend request, but we have to loop around
1874 // and check again. Eventually we will get SR_lock without a pending
1875 // external suspend request and will be able to mark ourselves as
1876 // exiting.
1877 }
1878 // no more external suspends are allowed at this point
1879 } else {
1880 // before_exit() has already posted JVMTI THREAD_END events
1881 }
1882
1883 // Notify waiters on thread object. This has to be done after exit() is called
1884 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1885 // group should have the destroyed bit set before waiters are notified).
1886 ensure_join(this);
1887 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1888
1889 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1890 // held by this thread must be released. The spec does not distinguish
1891 // between JNI-acquired and regular Java monitors. We can only see
1892 // regular Java monitors here if monitor enter-exit matching is broken.
1893 //
1894 // Optionally release any monitors for regular JavaThread exits. This
1895 // is provided as a work around for any bugs in monitor enter-exit
1896 // matching. This can be expensive so it is not enabled by default.
1897 //
1898 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1899 // ObjectSynchronizer::release_monitors_owned_by_thread().
1900 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1901 // Sanity check even though JNI DetachCurrentThread() would have
1902 // returned JNI_ERR if there was a Java frame. JavaThread exit
1903 // should be done executing Java code by the time we get here.
1904 assert(!this->has_last_Java_frame(),
1905 "should not have a Java frame when detaching or exiting");
1906 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1907 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1908 }
1909
1910 // These things needs to be done while we are still a Java Thread. Make sure that thread
1911 // is in a consistent state, in case GC happens
1912 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1913
1914 if (active_handles() != NULL) {
1915 JNIHandleBlock* block = active_handles();
1916 set_active_handles(NULL);
1917 JNIHandleBlock::release_block(block);
1918 }
1919
1920 if (free_handle_block() != NULL) {
1921 JNIHandleBlock* block = free_handle_block();
1922 set_free_handle_block(NULL);
1923 JNIHandleBlock::release_block(block);
1924 }
1925
1926 // These have to be removed while this is still a valid thread.
1927 remove_stack_guard_pages();
1928
1929 if (UseTLAB) {
1930 tlab().make_parsable(true); // retire TLAB
1931 }
1932
1933 if (JvmtiEnv::environments_might_exist()) {
1934 JvmtiExport::cleanup_thread(this);
1935 }
1936
1937 // We must flush any deferred card marks before removing a thread from
1938 // the list of active threads.
1939 Universe::heap()->flush_deferred_store_barrier(this);
1940 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1941
1942 #if INCLUDE_ALL_GCS
1943 // We must flush the G1-related buffers before removing a thread
1944 // from the list of active threads. We must do this after any deferred
1945 // card marks have been flushed (above) so that any entries that are
1946 // added to the thread's dirty card queue as a result are not lost.
1947 if (UseG1GC) {
1948 flush_barrier_queues();
1949 }
1950 #endif // INCLUDE_ALL_GCS
1951
1952 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1953 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1954 os::current_thread_id());
1955
1956 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1957 Threads::remove(this);
1958 }
1959
1960 #if INCLUDE_ALL_GCS
1961 // Flush G1-related queues.
1962 void JavaThread::flush_barrier_queues() {
1963 satb_mark_queue().flush();
1964 dirty_card_queue().flush();
1965 }
1966
1967 void JavaThread::initialize_queues() {
1968 assert(!SafepointSynchronize::is_at_safepoint(),
1969 "we should not be at a safepoint");
1970
1971 SATBMarkQueue& satb_queue = satb_mark_queue();
1972 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1973 // The SATB queue should have been constructed with its active
1974 // field set to false.
1975 assert(!satb_queue.is_active(), "SATB queue should not be active");
1976 assert(satb_queue.is_empty(), "SATB queue should be empty");
1977 // If we are creating the thread during a marking cycle, we should
1978 // set the active field of the SATB queue to true.
1979 if (satb_queue_set.is_active()) {
1980 satb_queue.set_active(true);
1981 }
1982
1983 DirtyCardQueue& dirty_queue = dirty_card_queue();
1984 // The dirty card queue should have been constructed with its
1985 // active field set to true.
1986 assert(dirty_queue.is_active(), "dirty card queue should be active");
1987 }
1988 #endif // INCLUDE_ALL_GCS
1989
1990 void JavaThread::cleanup_failed_attach_current_thread() {
1991 if (get_thread_profiler() != NULL) {
1992 get_thread_profiler()->disengage();
1993 ResourceMark rm;
1994 get_thread_profiler()->print(get_thread_name());
1995 }
1996
1997 if (active_handles() != NULL) {
1998 JNIHandleBlock* block = active_handles();
1999 set_active_handles(NULL);
2000 JNIHandleBlock::release_block(block);
2001 }
2002
2003 if (free_handle_block() != NULL) {
2004 JNIHandleBlock* block = free_handle_block();
2005 set_free_handle_block(NULL);
2006 JNIHandleBlock::release_block(block);
2007 }
2008
2009 // These have to be removed while this is still a valid thread.
2010 remove_stack_guard_pages();
2011
2012 if (UseTLAB) {
2013 tlab().make_parsable(true); // retire TLAB, if any
2014 }
2015
2016 #if INCLUDE_ALL_GCS
2017 if (UseG1GC) {
2018 flush_barrier_queues();
2019 }
2020 #endif // INCLUDE_ALL_GCS
2021
2022 Threads::remove(this);
2023 delete this;
2024 }
2025
2026
2027
2028
2029 JavaThread* JavaThread::active() {
2030 Thread* thread = Thread::current();
2031 if (thread->is_Java_thread()) {
2032 return (JavaThread*) thread;
2033 } else {
2034 assert(thread->is_VM_thread(), "this must be a vm thread");
2035 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2036 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2037 assert(ret->is_Java_thread(), "must be a Java thread");
2038 return ret;
2039 }
2040 }
2041
2042 bool JavaThread::is_lock_owned(address adr) const {
2043 if (Thread::is_lock_owned(adr)) return true;
2044
2045 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2046 if (chunk->contains(adr)) return true;
2047 }
2048
2049 return false;
2050 }
2051
2052
2053 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2054 chunk->set_next(monitor_chunks());
2055 set_monitor_chunks(chunk);
2056 }
2057
2058 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2059 guarantee(monitor_chunks() != NULL, "must be non empty");
2060 if (monitor_chunks() == chunk) {
2061 set_monitor_chunks(chunk->next());
2062 } else {
2063 MonitorChunk* prev = monitor_chunks();
2064 while (prev->next() != chunk) prev = prev->next();
2065 prev->set_next(chunk->next());
2066 }
2067 }
2068
2069 // JVM support.
2070
2071 // Note: this function shouldn't block if it's called in
2072 // _thread_in_native_trans state (such as from
2073 // check_special_condition_for_native_trans()).
2074 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2075
2076 if (has_last_Java_frame() && has_async_condition()) {
2077 // If we are at a polling page safepoint (not a poll return)
2078 // then we must defer async exception because live registers
2079 // will be clobbered by the exception path. Poll return is
2080 // ok because the call we a returning from already collides
2081 // with exception handling registers and so there is no issue.
2082 // (The exception handling path kills call result registers but
2083 // this is ok since the exception kills the result anyway).
2084
2085 if (is_at_poll_safepoint()) {
2086 // if the code we are returning to has deoptimized we must defer
2087 // the exception otherwise live registers get clobbered on the
2088 // exception path before deoptimization is able to retrieve them.
2089 //
2090 RegisterMap map(this, false);
2091 frame caller_fr = last_frame().sender(&map);
2092 assert(caller_fr.is_compiled_frame(), "what?");
2093 if (caller_fr.is_deoptimized_frame()) {
2094 log_info(exceptions)("deferred async exception at compiled safepoint");
2095 return;
2096 }
2097 }
2098 }
2099
2100 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2101 if (condition == _no_async_condition) {
2102 // Conditions have changed since has_special_runtime_exit_condition()
2103 // was called:
2104 // - if we were here only because of an external suspend request,
2105 // then that was taken care of above (or cancelled) so we are done
2106 // - if we were here because of another async request, then it has
2107 // been cleared between the has_special_runtime_exit_condition()
2108 // and now so again we are done
2109 return;
2110 }
2111
2112 // Check for pending async. exception
2113 if (_pending_async_exception != NULL) {
2114 // Only overwrite an already pending exception, if it is not a threadDeath.
2115 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2116
2117 // We cannot call Exceptions::_throw(...) here because we cannot block
2118 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2119
2120 if (log_is_enabled(Info, exceptions)) {
2121 ResourceMark rm;
2122 outputStream* logstream = Log(exceptions)::info_stream();
2123 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2124 if (has_last_Java_frame()) {
2125 frame f = last_frame();
2126 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2127 }
2128 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2129 }
2130 _pending_async_exception = NULL;
2131 clear_has_async_exception();
2132 }
2133 }
2134
2135 if (check_unsafe_error &&
2136 condition == _async_unsafe_access_error && !has_pending_exception()) {
2137 condition = _no_async_condition; // done
2138 switch (thread_state()) {
2139 case _thread_in_vm: {
2140 JavaThread* THREAD = this;
2141 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2142 }
2143 case _thread_in_native: {
2144 ThreadInVMfromNative tiv(this);
2145 JavaThread* THREAD = this;
2146 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2147 }
2148 case _thread_in_Java: {
2149 ThreadInVMfromJava tiv(this);
2150 JavaThread* THREAD = this;
2151 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2152 }
2153 default:
2154 ShouldNotReachHere();
2155 }
2156 }
2157
2158 assert(condition == _no_async_condition || has_pending_exception() ||
2159 (!check_unsafe_error && condition == _async_unsafe_access_error),
2160 "must have handled the async condition, if no exception");
2161 }
2162
2163 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2164 //
2165 // Check for pending external suspend. Internal suspend requests do
2166 // not use handle_special_runtime_exit_condition().
2167 // If JNIEnv proxies are allowed, don't self-suspend if the target
2168 // thread is not the current thread. In older versions of jdbx, jdbx
2169 // threads could call into the VM with another thread's JNIEnv so we
2170 // can be here operating on behalf of a suspended thread (4432884).
2171 bool do_self_suspend = is_external_suspend_with_lock();
2172 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2173 //
2174 // Because thread is external suspended the safepoint code will count
2175 // thread as at a safepoint. This can be odd because we can be here
2176 // as _thread_in_Java which would normally transition to _thread_blocked
2177 // at a safepoint. We would like to mark the thread as _thread_blocked
2178 // before calling java_suspend_self like all other callers of it but
2179 // we must then observe proper safepoint protocol. (We can't leave
2180 // _thread_blocked with a safepoint in progress). However we can be
2181 // here as _thread_in_native_trans so we can't use a normal transition
2182 // constructor/destructor pair because they assert on that type of
2183 // transition. We could do something like:
2184 //
2185 // JavaThreadState state = thread_state();
2186 // set_thread_state(_thread_in_vm);
2187 // {
2188 // ThreadBlockInVM tbivm(this);
2189 // java_suspend_self()
2190 // }
2191 // set_thread_state(_thread_in_vm_trans);
2192 // if (safepoint) block;
2193 // set_thread_state(state);
2194 //
2195 // but that is pretty messy. Instead we just go with the way the
2196 // code has worked before and note that this is the only path to
2197 // java_suspend_self that doesn't put the thread in _thread_blocked
2198 // mode.
2199
2200 frame_anchor()->make_walkable(this);
2201 java_suspend_self();
2202
2203 // We might be here for reasons in addition to the self-suspend request
2204 // so check for other async requests.
2205 }
2206
2207 if (check_asyncs) {
2208 check_and_handle_async_exceptions();
2209 }
2210 }
2211
2212 void JavaThread::send_thread_stop(oop java_throwable) {
2213 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2214 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2215 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2216
2217 // Do not throw asynchronous exceptions against the compiler thread
2218 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2219 if (!can_call_java()) return;
2220
2221 {
2222 // Actually throw the Throwable against the target Thread - however
2223 // only if there is no thread death exception installed already.
2224 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2225 // If the topmost frame is a runtime stub, then we are calling into
2226 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2227 // must deoptimize the caller before continuing, as the compiled exception handler table
2228 // may not be valid
2229 if (has_last_Java_frame()) {
2230 frame f = last_frame();
2231 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2232 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2233 RegisterMap reg_map(this, UseBiasedLocking);
2234 frame compiled_frame = f.sender(®_map);
2235 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2236 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2237 }
2238 }
2239 }
2240
2241 // Set async. pending exception in thread.
2242 set_pending_async_exception(java_throwable);
2243
2244 if (log_is_enabled(Info, exceptions)) {
2245 ResourceMark rm;
2246 log_info(exceptions)("Pending Async. exception installed of type: %s",
2247 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2248 }
2249 // for AbortVMOnException flag
2250 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2251 }
2252 }
2253
2254
2255 // Interrupt thread so it will wake up from a potential wait()
2256 Thread::interrupt(this);
2257 }
2258
2259 // External suspension mechanism.
2260 //
2261 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2262 // to any VM_locks and it is at a transition
2263 // Self-suspension will happen on the transition out of the vm.
2264 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2265 //
2266 // Guarantees on return:
2267 // + Target thread will not execute any new bytecode (that's why we need to
2268 // force a safepoint)
2269 // + Target thread will not enter any new monitors
2270 //
2271 void JavaThread::java_suspend() {
2272 { MutexLocker mu(Threads_lock);
2273 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2274 return;
2275 }
2276 }
2277
2278 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2279 if (!is_external_suspend()) {
2280 // a racing resume has cancelled us; bail out now
2281 return;
2282 }
2283
2284 // suspend is done
2285 uint32_t debug_bits = 0;
2286 // Warning: is_ext_suspend_completed() may temporarily drop the
2287 // SR_lock to allow the thread to reach a stable thread state if
2288 // it is currently in a transient thread state.
2289 if (is_ext_suspend_completed(false /* !called_by_wait */,
2290 SuspendRetryDelay, &debug_bits)) {
2291 return;
2292 }
2293 }
2294
2295 VM_ForceSafepoint vm_suspend;
2296 VMThread::execute(&vm_suspend);
2297 }
2298
2299 // Part II of external suspension.
2300 // A JavaThread self suspends when it detects a pending external suspend
2301 // request. This is usually on transitions. It is also done in places
2302 // where continuing to the next transition would surprise the caller,
2303 // e.g., monitor entry.
2304 //
2305 // Returns the number of times that the thread self-suspended.
2306 //
2307 // Note: DO NOT call java_suspend_self() when you just want to block current
2308 // thread. java_suspend_self() is the second stage of cooperative
2309 // suspension for external suspend requests and should only be used
2310 // to complete an external suspend request.
2311 //
2312 int JavaThread::java_suspend_self() {
2313 int ret = 0;
2314
2315 // we are in the process of exiting so don't suspend
2316 if (is_exiting()) {
2317 clear_external_suspend();
2318 return ret;
2319 }
2320
2321 assert(_anchor.walkable() ||
2322 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2323 "must have walkable stack");
2324
2325 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2326
2327 assert(!this->is_ext_suspended(),
2328 "a thread trying to self-suspend should not already be suspended");
2329
2330 if (this->is_suspend_equivalent()) {
2331 // If we are self-suspending as a result of the lifting of a
2332 // suspend equivalent condition, then the suspend_equivalent
2333 // flag is not cleared until we set the ext_suspended flag so
2334 // that wait_for_ext_suspend_completion() returns consistent
2335 // results.
2336 this->clear_suspend_equivalent();
2337 }
2338
2339 // A racing resume may have cancelled us before we grabbed SR_lock
2340 // above. Or another external suspend request could be waiting for us
2341 // by the time we return from SR_lock()->wait(). The thread
2342 // that requested the suspension may already be trying to walk our
2343 // stack and if we return now, we can change the stack out from under
2344 // it. This would be a "bad thing (TM)" and cause the stack walker
2345 // to crash. We stay self-suspended until there are no more pending
2346 // external suspend requests.
2347 while (is_external_suspend()) {
2348 ret++;
2349 this->set_ext_suspended();
2350
2351 // _ext_suspended flag is cleared by java_resume()
2352 while (is_ext_suspended()) {
2353 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2354 }
2355 }
2356
2357 return ret;
2358 }
2359
2360 #ifdef ASSERT
2361 // verify the JavaThread has not yet been published in the Threads::list, and
2362 // hence doesn't need protection from concurrent access at this stage
2363 void JavaThread::verify_not_published() {
2364 if (!Threads_lock->owned_by_self()) {
2365 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2366 assert(!Threads::includes(this),
2367 "java thread shouldn't have been published yet!");
2368 } else {
2369 assert(!Threads::includes(this),
2370 "java thread shouldn't have been published yet!");
2371 }
2372 }
2373 #endif
2374
2375 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2376 // progress or when _suspend_flags is non-zero.
2377 // Current thread needs to self-suspend if there is a suspend request and/or
2378 // block if a safepoint is in progress.
2379 // Async exception ISN'T checked.
2380 // Note only the ThreadInVMfromNative transition can call this function
2381 // directly and when thread state is _thread_in_native_trans
2382 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2383 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2384
2385 JavaThread *curJT = JavaThread::current();
2386 bool do_self_suspend = thread->is_external_suspend();
2387
2388 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2389
2390 // If JNIEnv proxies are allowed, don't self-suspend if the target
2391 // thread is not the current thread. In older versions of jdbx, jdbx
2392 // threads could call into the VM with another thread's JNIEnv so we
2393 // can be here operating on behalf of a suspended thread (4432884).
2394 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2395 JavaThreadState state = thread->thread_state();
2396
2397 // We mark this thread_blocked state as a suspend-equivalent so
2398 // that a caller to is_ext_suspend_completed() won't be confused.
2399 // The suspend-equivalent state is cleared by java_suspend_self().
2400 thread->set_suspend_equivalent();
2401
2402 // If the safepoint code sees the _thread_in_native_trans state, it will
2403 // wait until the thread changes to other thread state. There is no
2404 // guarantee on how soon we can obtain the SR_lock and complete the
2405 // self-suspend request. It would be a bad idea to let safepoint wait for
2406 // too long. Temporarily change the state to _thread_blocked to
2407 // let the VM thread know that this thread is ready for GC. The problem
2408 // of changing thread state is that safepoint could happen just after
2409 // java_suspend_self() returns after being resumed, and VM thread will
2410 // see the _thread_blocked state. We must check for safepoint
2411 // after restoring the state and make sure we won't leave while a safepoint
2412 // is in progress.
2413 thread->set_thread_state(_thread_blocked);
2414 thread->java_suspend_self();
2415 thread->set_thread_state(state);
2416 // Make sure new state is seen by VM thread
2417 if (os::is_MP()) {
2418 if (UseMembar) {
2419 // Force a fence between the write above and read below
2420 OrderAccess::fence();
2421 } else {
2422 // Must use this rather than serialization page in particular on Windows
2423 InterfaceSupport::serialize_memory(thread);
2424 }
2425 }
2426 }
2427
2428 if (SafepointSynchronize::do_call_back()) {
2429 // If we are safepointing, then block the caller which may not be
2430 // the same as the target thread (see above).
2431 SafepointSynchronize::block(curJT);
2432 }
2433
2434 if (thread->is_deopt_suspend()) {
2435 thread->clear_deopt_suspend();
2436 RegisterMap map(thread, false);
2437 frame f = thread->last_frame();
2438 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2439 f = f.sender(&map);
2440 }
2441 if (f.id() == thread->must_deopt_id()) {
2442 thread->clear_must_deopt_id();
2443 f.deoptimize(thread);
2444 } else {
2445 fatal("missed deoptimization!");
2446 }
2447 }
2448 }
2449
2450 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2451 // progress or when _suspend_flags is non-zero.
2452 // Current thread needs to self-suspend if there is a suspend request and/or
2453 // block if a safepoint is in progress.
2454 // Also check for pending async exception (not including unsafe access error).
2455 // Note only the native==>VM/Java barriers can call this function and when
2456 // thread state is _thread_in_native_trans.
2457 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2458 check_safepoint_and_suspend_for_native_trans(thread);
2459
2460 if (thread->has_async_exception()) {
2461 // We are in _thread_in_native_trans state, don't handle unsafe
2462 // access error since that may block.
2463 thread->check_and_handle_async_exceptions(false);
2464 }
2465 }
2466
2467 // This is a variant of the normal
2468 // check_special_condition_for_native_trans with slightly different
2469 // semantics for use by critical native wrappers. It does all the
2470 // normal checks but also performs the transition back into
2471 // thread_in_Java state. This is required so that critical natives
2472 // can potentially block and perform a GC if they are the last thread
2473 // exiting the GCLocker.
2474 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2475 check_special_condition_for_native_trans(thread);
2476
2477 // Finish the transition
2478 thread->set_thread_state(_thread_in_Java);
2479
2480 if (thread->do_critical_native_unlock()) {
2481 ThreadInVMfromJavaNoAsyncException tiv(thread);
2482 GCLocker::unlock_critical(thread);
2483 thread->clear_critical_native_unlock();
2484 }
2485 }
2486
2487 // We need to guarantee the Threads_lock here, since resumes are not
2488 // allowed during safepoint synchronization
2489 // Can only resume from an external suspension
2490 void JavaThread::java_resume() {
2491 assert_locked_or_safepoint(Threads_lock);
2492
2493 // Sanity check: thread is gone, has started exiting or the thread
2494 // was not externally suspended.
2495 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2496 return;
2497 }
2498
2499 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2500
2501 clear_external_suspend();
2502
2503 if (is_ext_suspended()) {
2504 clear_ext_suspended();
2505 SR_lock()->notify_all();
2506 }
2507 }
2508
2509 size_t JavaThread::_stack_red_zone_size = 0;
2510 size_t JavaThread::_stack_yellow_zone_size = 0;
2511 size_t JavaThread::_stack_reserved_zone_size = 0;
2512 size_t JavaThread::_stack_shadow_zone_size = 0;
2513
2514 void JavaThread::create_stack_guard_pages() {
2515 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2516 address low_addr = stack_end();
2517 size_t len = stack_guard_zone_size();
2518
2519 int must_commit = os::must_commit_stack_guard_pages();
2520 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2521
2522 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2523 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2524 return;
2525 }
2526
2527 if (os::guard_memory((char *) low_addr, len)) {
2528 _stack_guard_state = stack_guard_enabled;
2529 } else {
2530 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2531 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2532 if (os::uncommit_memory((char *) low_addr, len)) {
2533 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2534 }
2535 return;
2536 }
2537
2538 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2539 PTR_FORMAT "-" PTR_FORMAT ".",
2540 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2541 }
2542
2543 void JavaThread::remove_stack_guard_pages() {
2544 assert(Thread::current() == this, "from different thread");
2545 if (_stack_guard_state == stack_guard_unused) return;
2546 address low_addr = stack_end();
2547 size_t len = stack_guard_zone_size();
2548
2549 if (os::must_commit_stack_guard_pages()) {
2550 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2551 _stack_guard_state = stack_guard_unused;
2552 } else {
2553 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2554 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2555 return;
2556 }
2557 } else {
2558 if (_stack_guard_state == stack_guard_unused) return;
2559 if (os::unguard_memory((char *) low_addr, len)) {
2560 _stack_guard_state = stack_guard_unused;
2561 } else {
2562 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2563 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2564 return;
2565 }
2566 }
2567
2568 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2569 PTR_FORMAT "-" PTR_FORMAT ".",
2570 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2571 }
2572
2573 void JavaThread::enable_stack_reserved_zone() {
2574 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2575 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2576
2577 // The base notation is from the stack's point of view, growing downward.
2578 // We need to adjust it to work correctly with guard_memory()
2579 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2580
2581 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2582 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2583
2584 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2585 _stack_guard_state = stack_guard_enabled;
2586 } else {
2587 warning("Attempt to guard stack reserved zone failed.");
2588 }
2589 enable_register_stack_guard();
2590 }
2591
2592 void JavaThread::disable_stack_reserved_zone() {
2593 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2594 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2595
2596 // Simply return if called for a thread that does not use guard pages.
2597 if (_stack_guard_state == stack_guard_unused) return;
2598
2599 // The base notation is from the stack's point of view, growing downward.
2600 // We need to adjust it to work correctly with guard_memory()
2601 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2602
2603 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2604 _stack_guard_state = stack_guard_reserved_disabled;
2605 } else {
2606 warning("Attempt to unguard stack reserved zone failed.");
2607 }
2608 disable_register_stack_guard();
2609 }
2610
2611 void JavaThread::enable_stack_yellow_reserved_zone() {
2612 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2613 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2614
2615 // The base notation is from the stacks point of view, growing downward.
2616 // We need to adjust it to work correctly with guard_memory()
2617 address base = stack_red_zone_base();
2618
2619 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2620 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2621
2622 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2623 _stack_guard_state = stack_guard_enabled;
2624 } else {
2625 warning("Attempt to guard stack yellow zone failed.");
2626 }
2627 enable_register_stack_guard();
2628 }
2629
2630 void JavaThread::disable_stack_yellow_reserved_zone() {
2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2632 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2633
2634 // Simply return if called for a thread that does not use guard pages.
2635 if (_stack_guard_state == stack_guard_unused) return;
2636
2637 // The base notation is from the stacks point of view, growing downward.
2638 // We need to adjust it to work correctly with guard_memory()
2639 address base = stack_red_zone_base();
2640
2641 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2642 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2643 } else {
2644 warning("Attempt to unguard stack yellow zone failed.");
2645 }
2646 disable_register_stack_guard();
2647 }
2648
2649 void JavaThread::enable_stack_red_zone() {
2650 // The base notation is from the stacks point of view, growing downward.
2651 // We need to adjust it to work correctly with guard_memory()
2652 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2653 address base = stack_red_zone_base() - stack_red_zone_size();
2654
2655 guarantee(base < stack_base(), "Error calculating stack red zone");
2656 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2657
2658 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2659 warning("Attempt to guard stack red zone failed.");
2660 }
2661 }
2662
2663 void JavaThread::disable_stack_red_zone() {
2664 // The base notation is from the stacks point of view, growing downward.
2665 // We need to adjust it to work correctly with guard_memory()
2666 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2667 address base = stack_red_zone_base() - stack_red_zone_size();
2668 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2669 warning("Attempt to unguard stack red zone failed.");
2670 }
2671 }
2672
2673 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2674 // ignore is there is no stack
2675 if (!has_last_Java_frame()) return;
2676 // traverse the stack frames. Starts from top frame.
2677 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2678 frame* fr = fst.current();
2679 f(fr, fst.register_map());
2680 }
2681 }
2682
2683
2684 #ifndef PRODUCT
2685 // Deoptimization
2686 // Function for testing deoptimization
2687 void JavaThread::deoptimize() {
2688 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2689 StackFrameStream fst(this, UseBiasedLocking);
2690 bool deopt = false; // Dump stack only if a deopt actually happens.
2691 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2692 // Iterate over all frames in the thread and deoptimize
2693 for (; !fst.is_done(); fst.next()) {
2694 if (fst.current()->can_be_deoptimized()) {
2695
2696 if (only_at) {
2697 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2698 // consists of comma or carriage return separated numbers so
2699 // search for the current bci in that string.
2700 address pc = fst.current()->pc();
2701 nmethod* nm = (nmethod*) fst.current()->cb();
2702 ScopeDesc* sd = nm->scope_desc_at(pc);
2703 char buffer[8];
2704 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2705 size_t len = strlen(buffer);
2706 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2707 while (found != NULL) {
2708 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2709 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2710 // Check that the bci found is bracketed by terminators.
2711 break;
2712 }
2713 found = strstr(found + 1, buffer);
2714 }
2715 if (!found) {
2716 continue;
2717 }
2718 }
2719
2720 if (DebugDeoptimization && !deopt) {
2721 deopt = true; // One-time only print before deopt
2722 tty->print_cr("[BEFORE Deoptimization]");
2723 trace_frames();
2724 trace_stack();
2725 }
2726 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2727 }
2728 }
2729
2730 if (DebugDeoptimization && deopt) {
2731 tty->print_cr("[AFTER Deoptimization]");
2732 trace_frames();
2733 }
2734 }
2735
2736
2737 // Make zombies
2738 void JavaThread::make_zombies() {
2739 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2740 if (fst.current()->can_be_deoptimized()) {
2741 // it is a Java nmethod
2742 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2743 nm->make_not_entrant();
2744 }
2745 }
2746 }
2747 #endif // PRODUCT
2748
2749
2750 void JavaThread::deoptimized_wrt_marked_nmethods() {
2751 if (!has_last_Java_frame()) return;
2752 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2753 StackFrameStream fst(this, UseBiasedLocking);
2754 for (; !fst.is_done(); fst.next()) {
2755 if (fst.current()->should_be_deoptimized()) {
2756 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2757 }
2758 }
2759 }
2760
2761
2762 // If the caller is a NamedThread, then remember, in the current scope,
2763 // the given JavaThread in its _processed_thread field.
2764 class RememberProcessedThread: public StackObj {
2765 NamedThread* _cur_thr;
2766 public:
2767 RememberProcessedThread(JavaThread* jthr) {
2768 Thread* thread = Thread::current();
2769 if (thread->is_Named_thread()) {
2770 _cur_thr = (NamedThread *)thread;
2771 _cur_thr->set_processed_thread(jthr);
2772 } else {
2773 _cur_thr = NULL;
2774 }
2775 }
2776
2777 ~RememberProcessedThread() {
2778 if (_cur_thr) {
2779 _cur_thr->set_processed_thread(NULL);
2780 }
2781 }
2782 };
2783
2784 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2785 // Verify that the deferred card marks have been flushed.
2786 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2787
2788 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2789 // since there may be more than one thread using each ThreadProfiler.
2790
2791 // Traverse the GCHandles
2792 Thread::oops_do(f, cf);
2793
2794 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2795
2796 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2797 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2798
2799 if (has_last_Java_frame()) {
2800 // Record JavaThread to GC thread
2801 RememberProcessedThread rpt(this);
2802
2803 // Traverse the privileged stack
2804 if (_privileged_stack_top != NULL) {
2805 _privileged_stack_top->oops_do(f);
2806 }
2807
2808 // traverse the registered growable array
2809 if (_array_for_gc != NULL) {
2810 for (int index = 0; index < _array_for_gc->length(); index++) {
2811 f->do_oop(_array_for_gc->adr_at(index));
2812 }
2813 }
2814
2815 // Traverse the monitor chunks
2816 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2817 chunk->oops_do(f);
2818 }
2819
2820 // Traverse the execution stack
2821 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2822 fst.current()->oops_do(f, cf, fst.register_map());
2823 }
2824 }
2825
2826 // callee_target is never live across a gc point so NULL it here should
2827 // it still contain a methdOop.
2828
2829 set_callee_target(NULL);
2830
2831 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2832 // If we have deferred set_locals there might be oops waiting to be
2833 // written
2834 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2835 if (list != NULL) {
2836 for (int i = 0; i < list->length(); i++) {
2837 list->at(i)->oops_do(f);
2838 }
2839 }
2840
2841 // Traverse instance variables at the end since the GC may be moving things
2842 // around using this function
2843 f->do_oop((oop*) &_threadObj);
2844 // if (Universe::heap()->is_in_reserved_or_null((void*)_vm_result)) {
2845 if (!VTBufferChunk::check_buffered(&_vm_result)) {
2846 f->do_oop((oop*) &_vm_result);
2847 }
2848 f->do_oop((oop*) &_exception_oop);
2849 f->do_oop((oop*) &_pending_async_exception);
2850
2851 if (jvmti_thread_state() != NULL) {
2852 jvmti_thread_state()->oops_do(f);
2853 }
2854 }
2855
2856 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2857 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2858 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2859
2860 if (has_last_Java_frame()) {
2861 // Traverse the execution stack
2862 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2863 fst.current()->nmethods_do(cf);
2864 }
2865 }
2866 }
2867
2868 void JavaThread::metadata_do(void f(Metadata*)) {
2869 if (has_last_Java_frame()) {
2870 // Traverse the execution stack to call f() on the methods in the stack
2871 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2872 fst.current()->metadata_do(f);
2873 }
2874 } else if (is_Compiler_thread()) {
2875 // need to walk ciMetadata in current compile tasks to keep alive.
2876 CompilerThread* ct = (CompilerThread*)this;
2877 if (ct->env() != NULL) {
2878 ct->env()->metadata_do(f);
2879 }
2880 if (ct->task() != NULL) {
2881 ct->task()->metadata_do(f);
2882 }
2883 }
2884 }
2885
2886 // Printing
2887 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2888 switch (_thread_state) {
2889 case _thread_uninitialized: return "_thread_uninitialized";
2890 case _thread_new: return "_thread_new";
2891 case _thread_new_trans: return "_thread_new_trans";
2892 case _thread_in_native: return "_thread_in_native";
2893 case _thread_in_native_trans: return "_thread_in_native_trans";
2894 case _thread_in_vm: return "_thread_in_vm";
2895 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2896 case _thread_in_Java: return "_thread_in_Java";
2897 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2898 case _thread_blocked: return "_thread_blocked";
2899 case _thread_blocked_trans: return "_thread_blocked_trans";
2900 default: return "unknown thread state";
2901 }
2902 }
2903
2904 #ifndef PRODUCT
2905 void JavaThread::print_thread_state_on(outputStream *st) const {
2906 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2907 };
2908 void JavaThread::print_thread_state() const {
2909 print_thread_state_on(tty);
2910 }
2911 #endif // PRODUCT
2912
2913 // Called by Threads::print() for VM_PrintThreads operation
2914 void JavaThread::print_on(outputStream *st) const {
2915 st->print_raw("\"");
2916 st->print_raw(get_thread_name());
2917 st->print_raw("\" ");
2918 oop thread_oop = threadObj();
2919 if (thread_oop != NULL) {
2920 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2921 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2922 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2923 }
2924 Thread::print_on(st);
2925 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2926 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2927 if (thread_oop != NULL) {
2928 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2929 }
2930 #ifndef PRODUCT
2931 print_thread_state_on(st);
2932 _safepoint_state->print_on(st);
2933 #endif // PRODUCT
2934 if (is_Compiler_thread()) {
2935 CompilerThread* ct = (CompilerThread*)this;
2936 if (ct->task() != NULL) {
2937 st->print(" Compiling: ");
2938 ct->task()->print(st, NULL, true, false);
2939 } else {
2940 st->print(" No compile task");
2941 }
2942 st->cr();
2943 }
2944 }
2945
2946 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2947 st->print("%s", get_thread_name_string(buf, buflen));
2948 }
2949
2950 // Called by fatal error handler. The difference between this and
2951 // JavaThread::print() is that we can't grab lock or allocate memory.
2952 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2953 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2954 oop thread_obj = threadObj();
2955 if (thread_obj != NULL) {
2956 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2957 }
2958 st->print(" [");
2959 st->print("%s", _get_thread_state_name(_thread_state));
2960 if (osthread()) {
2961 st->print(", id=%d", osthread()->thread_id());
2962 }
2963 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2964 p2i(stack_end()), p2i(stack_base()));
2965 st->print("]");
2966 return;
2967 }
2968
2969 // Verification
2970
2971 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2972
2973 void JavaThread::verify() {
2974 // Verify oops in the thread.
2975 oops_do(&VerifyOopClosure::verify_oop, NULL);
2976
2977 // Verify the stack frames.
2978 frames_do(frame_verify);
2979 }
2980
2981 // CR 6300358 (sub-CR 2137150)
2982 // Most callers of this method assume that it can't return NULL but a
2983 // thread may not have a name whilst it is in the process of attaching to
2984 // the VM - see CR 6412693, and there are places where a JavaThread can be
2985 // seen prior to having it's threadObj set (eg JNI attaching threads and
2986 // if vm exit occurs during initialization). These cases can all be accounted
2987 // for such that this method never returns NULL.
2988 const char* JavaThread::get_thread_name() const {
2989 #ifdef ASSERT
2990 // early safepoints can hit while current thread does not yet have TLS
2991 if (!SafepointSynchronize::is_at_safepoint()) {
2992 Thread *cur = Thread::current();
2993 if (!(cur->is_Java_thread() && cur == this)) {
2994 // Current JavaThreads are allowed to get their own name without
2995 // the Threads_lock.
2996 assert_locked_or_safepoint(Threads_lock);
2997 }
2998 }
2999 #endif // ASSERT
3000 return get_thread_name_string();
3001 }
3002
3003 // Returns a non-NULL representation of this thread's name, or a suitable
3004 // descriptive string if there is no set name
3005 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3006 const char* name_str;
3007 oop thread_obj = threadObj();
3008 if (thread_obj != NULL) {
3009 oop name = java_lang_Thread::name(thread_obj);
3010 if (name != NULL) {
3011 if (buf == NULL) {
3012 name_str = java_lang_String::as_utf8_string(name);
3013 } else {
3014 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3015 }
3016 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3017 name_str = "<no-name - thread is attaching>";
3018 } else {
3019 name_str = Thread::name();
3020 }
3021 } else {
3022 name_str = Thread::name();
3023 }
3024 assert(name_str != NULL, "unexpected NULL thread name");
3025 return name_str;
3026 }
3027
3028
3029 const char* JavaThread::get_threadgroup_name() const {
3030 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3031 oop thread_obj = threadObj();
3032 if (thread_obj != NULL) {
3033 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3034 if (thread_group != NULL) {
3035 // ThreadGroup.name can be null
3036 return java_lang_ThreadGroup::name(thread_group);
3037 }
3038 }
3039 return NULL;
3040 }
3041
3042 const char* JavaThread::get_parent_name() const {
3043 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3044 oop thread_obj = threadObj();
3045 if (thread_obj != NULL) {
3046 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3047 if (thread_group != NULL) {
3048 oop parent = java_lang_ThreadGroup::parent(thread_group);
3049 if (parent != NULL) {
3050 // ThreadGroup.name can be null
3051 return java_lang_ThreadGroup::name(parent);
3052 }
3053 }
3054 }
3055 return NULL;
3056 }
3057
3058 ThreadPriority JavaThread::java_priority() const {
3059 oop thr_oop = threadObj();
3060 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3061 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3062 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3063 return priority;
3064 }
3065
3066 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3067
3068 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3069 // Link Java Thread object <-> C++ Thread
3070
3071 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3072 // and put it into a new Handle. The Handle "thread_oop" can then
3073 // be used to pass the C++ thread object to other methods.
3074
3075 // Set the Java level thread object (jthread) field of the
3076 // new thread (a JavaThread *) to C++ thread object using the
3077 // "thread_oop" handle.
3078
3079 // Set the thread field (a JavaThread *) of the
3080 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3081
3082 Handle thread_oop(Thread::current(),
3083 JNIHandles::resolve_non_null(jni_thread));
3084 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3085 "must be initialized");
3086 set_threadObj(thread_oop());
3087 java_lang_Thread::set_thread(thread_oop(), this);
3088
3089 if (prio == NoPriority) {
3090 prio = java_lang_Thread::priority(thread_oop());
3091 assert(prio != NoPriority, "A valid priority should be present");
3092 }
3093
3094 // Push the Java priority down to the native thread; needs Threads_lock
3095 Thread::set_priority(this, prio);
3096
3097 prepare_ext();
3098
3099 // Add the new thread to the Threads list and set it in motion.
3100 // We must have threads lock in order to call Threads::add.
3101 // It is crucial that we do not block before the thread is
3102 // added to the Threads list for if a GC happens, then the java_thread oop
3103 // will not be visited by GC.
3104 Threads::add(this);
3105 }
3106
3107 oop JavaThread::current_park_blocker() {
3108 // Support for JSR-166 locks
3109 oop thread_oop = threadObj();
3110 if (thread_oop != NULL &&
3111 JDK_Version::current().supports_thread_park_blocker()) {
3112 return java_lang_Thread::park_blocker(thread_oop);
3113 }
3114 return NULL;
3115 }
3116
3117
3118 void JavaThread::print_stack_on(outputStream* st) {
3119 if (!has_last_Java_frame()) return;
3120 ResourceMark rm;
3121 HandleMark hm;
3122
3123 RegisterMap reg_map(this);
3124 vframe* start_vf = last_java_vframe(®_map);
3125 int count = 0;
3126 for (vframe* f = start_vf; f; f = f->sender()) {
3127 if (f->is_java_frame()) {
3128 javaVFrame* jvf = javaVFrame::cast(f);
3129 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3130
3131 // Print out lock information
3132 if (JavaMonitorsInStackTrace) {
3133 jvf->print_lock_info_on(st, count);
3134 }
3135 } else {
3136 // Ignore non-Java frames
3137 }
3138
3139 // Bail-out case for too deep stacks
3140 count++;
3141 if (MaxJavaStackTraceDepth == count) return;
3142 }
3143 }
3144
3145
3146 // JVMTI PopFrame support
3147 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3148 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3149 if (in_bytes(size_in_bytes) != 0) {
3150 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3151 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3152 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3153 }
3154 }
3155
3156 void* JavaThread::popframe_preserved_args() {
3157 return _popframe_preserved_args;
3158 }
3159
3160 ByteSize JavaThread::popframe_preserved_args_size() {
3161 return in_ByteSize(_popframe_preserved_args_size);
3162 }
3163
3164 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3165 int sz = in_bytes(popframe_preserved_args_size());
3166 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3167 return in_WordSize(sz / wordSize);
3168 }
3169
3170 void JavaThread::popframe_free_preserved_args() {
3171 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3172 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3173 _popframe_preserved_args = NULL;
3174 _popframe_preserved_args_size = 0;
3175 }
3176
3177 #ifndef PRODUCT
3178
3179 void JavaThread::trace_frames() {
3180 tty->print_cr("[Describe stack]");
3181 int frame_no = 1;
3182 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3183 tty->print(" %d. ", frame_no++);
3184 fst.current()->print_value_on(tty, this);
3185 tty->cr();
3186 }
3187 }
3188
3189 class PrintAndVerifyOopClosure: public OopClosure {
3190 protected:
3191 template <class T> inline void do_oop_work(T* p) {
3192 oop obj = oopDesc::load_decode_heap_oop(p);
3193 if (obj == NULL) return;
3194 tty->print(INTPTR_FORMAT ": ", p2i(p));
3195 if (obj->is_oop_or_null()) {
3196 if (obj->is_objArray()) {
3197 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3198 } else {
3199 obj->print();
3200 }
3201 } else {
3202 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3203 }
3204 tty->cr();
3205 }
3206 public:
3207 virtual void do_oop(oop* p) { do_oop_work(p); }
3208 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3209 };
3210
3211
3212 static void oops_print(frame* f, const RegisterMap *map) {
3213 PrintAndVerifyOopClosure print;
3214 f->print_value();
3215 f->oops_do(&print, NULL, (RegisterMap*)map);
3216 }
3217
3218 // Print our all the locations that contain oops and whether they are
3219 // valid or not. This useful when trying to find the oldest frame
3220 // where an oop has gone bad since the frame walk is from youngest to
3221 // oldest.
3222 void JavaThread::trace_oops() {
3223 tty->print_cr("[Trace oops]");
3224 frames_do(oops_print);
3225 }
3226
3227
3228 #ifdef ASSERT
3229 // Print or validate the layout of stack frames
3230 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3231 ResourceMark rm;
3232 PRESERVE_EXCEPTION_MARK;
3233 FrameValues values;
3234 int frame_no = 0;
3235 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3236 fst.current()->describe(values, ++frame_no);
3237 if (depth == frame_no) break;
3238 }
3239 if (validate_only) {
3240 values.validate();
3241 } else {
3242 tty->print_cr("[Describe stack layout]");
3243 values.print(this);
3244 }
3245 }
3246 #endif
3247
3248 void JavaThread::trace_stack_from(vframe* start_vf) {
3249 ResourceMark rm;
3250 int vframe_no = 1;
3251 for (vframe* f = start_vf; f; f = f->sender()) {
3252 if (f->is_java_frame()) {
3253 javaVFrame::cast(f)->print_activation(vframe_no++);
3254 } else {
3255 f->print();
3256 }
3257 if (vframe_no > StackPrintLimit) {
3258 tty->print_cr("...<more frames>...");
3259 return;
3260 }
3261 }
3262 }
3263
3264
3265 void JavaThread::trace_stack() {
3266 if (!has_last_Java_frame()) return;
3267 ResourceMark rm;
3268 HandleMark hm;
3269 RegisterMap reg_map(this);
3270 trace_stack_from(last_java_vframe(®_map));
3271 }
3272
3273
3274 #endif // PRODUCT
3275
3276
3277 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3278 assert(reg_map != NULL, "a map must be given");
3279 frame f = last_frame();
3280 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3281 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3282 }
3283 return NULL;
3284 }
3285
3286
3287 Klass* JavaThread::security_get_caller_class(int depth) {
3288 vframeStream vfst(this);
3289 vfst.security_get_caller_frame(depth);
3290 if (!vfst.at_end()) {
3291 return vfst.method()->method_holder();
3292 }
3293 return NULL;
3294 }
3295
3296 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3297 assert(thread->is_Compiler_thread(), "must be compiler thread");
3298 CompileBroker::compiler_thread_loop();
3299 }
3300
3301 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3302 NMethodSweeper::sweeper_loop();
3303 }
3304
3305 // Create a CompilerThread
3306 CompilerThread::CompilerThread(CompileQueue* queue,
3307 CompilerCounters* counters)
3308 : JavaThread(&compiler_thread_entry) {
3309 _env = NULL;
3310 _log = NULL;
3311 _task = NULL;
3312 _queue = queue;
3313 _counters = counters;
3314 _buffer_blob = NULL;
3315 _compiler = NULL;
3316
3317 #ifndef PRODUCT
3318 _ideal_graph_printer = NULL;
3319 #endif
3320 }
3321
3322 bool CompilerThread::can_call_java() const {
3323 return _compiler != NULL && _compiler->is_jvmci();
3324 }
3325
3326 // Create sweeper thread
3327 CodeCacheSweeperThread::CodeCacheSweeperThread()
3328 : JavaThread(&sweeper_thread_entry) {
3329 _scanned_compiled_method = NULL;
3330 }
3331
3332 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3333 JavaThread::oops_do(f, cf);
3334 if (_scanned_compiled_method != NULL && cf != NULL) {
3335 // Safepoints can occur when the sweeper is scanning an nmethod so
3336 // process it here to make sure it isn't unloaded in the middle of
3337 // a scan.
3338 cf->do_code_blob(_scanned_compiled_method);
3339 }
3340 }
3341
3342 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3343 JavaThread::nmethods_do(cf);
3344 if (_scanned_compiled_method != NULL && cf != NULL) {
3345 // Safepoints can occur when the sweeper is scanning an nmethod so
3346 // process it here to make sure it isn't unloaded in the middle of
3347 // a scan.
3348 cf->do_code_blob(_scanned_compiled_method);
3349 }
3350 }
3351
3352
3353 // ======= Threads ========
3354
3355 // The Threads class links together all active threads, and provides
3356 // operations over all threads. It is protected by its own Mutex
3357 // lock, which is also used in other contexts to protect thread
3358 // operations from having the thread being operated on from exiting
3359 // and going away unexpectedly (e.g., safepoint synchronization)
3360
3361 JavaThread* Threads::_thread_list = NULL;
3362 int Threads::_number_of_threads = 0;
3363 int Threads::_number_of_non_daemon_threads = 0;
3364 int Threads::_return_code = 0;
3365 int Threads::_thread_claim_parity = 0;
3366 size_t JavaThread::_stack_size_at_create = 0;
3367 #ifdef ASSERT
3368 bool Threads::_vm_complete = false;
3369 #endif
3370
3371 // All JavaThreads
3372 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3373
3374 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3375 void Threads::threads_do(ThreadClosure* tc) {
3376 assert_locked_or_safepoint(Threads_lock);
3377 // ALL_JAVA_THREADS iterates through all JavaThreads
3378 ALL_JAVA_THREADS(p) {
3379 tc->do_thread(p);
3380 }
3381 // Someday we could have a table or list of all non-JavaThreads.
3382 // For now, just manually iterate through them.
3383 tc->do_thread(VMThread::vm_thread());
3384 Universe::heap()->gc_threads_do(tc);
3385 WatcherThread *wt = WatcherThread::watcher_thread();
3386 // Strictly speaking, the following NULL check isn't sufficient to make sure
3387 // the data for WatcherThread is still valid upon being examined. However,
3388 // considering that WatchThread terminates when the VM is on the way to
3389 // exit at safepoint, the chance of the above is extremely small. The right
3390 // way to prevent termination of WatcherThread would be to acquire
3391 // Terminator_lock, but we can't do that without violating the lock rank
3392 // checking in some cases.
3393 if (wt != NULL) {
3394 tc->do_thread(wt);
3395 }
3396
3397 // If CompilerThreads ever become non-JavaThreads, add them here
3398 }
3399
3400 // The system initialization in the library has three phases.
3401 //
3402 // Phase 1: java.lang.System class initialization
3403 // java.lang.System is a primordial class loaded and initialized
3404 // by the VM early during startup. java.lang.System.<clinit>
3405 // only does registerNatives and keeps the rest of the class
3406 // initialization work later until thread initialization completes.
3407 //
3408 // System.initPhase1 initializes the system properties, the static
3409 // fields in, out, and err. Set up java signal handlers, OS-specific
3410 // system settings, and thread group of the main thread.
3411 static void call_initPhase1(TRAPS) {
3412 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3413 JavaValue result(T_VOID);
3414 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3415 vmSymbols::void_method_signature(), CHECK);
3416 }
3417
3418 // Phase 2. Module system initialization
3419 // This will initialize the module system. Only java.base classes
3420 // can be loaded until phase 2 completes.
3421 //
3422 // Call System.initPhase2 after the compiler initialization and jsr292
3423 // classes get initialized because module initialization runs a lot of java
3424 // code, that for performance reasons, should be compiled. Also, this will
3425 // enable the startup code to use lambda and other language features in this
3426 // phase and onward.
3427 //
3428 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3429 static void call_initPhase2(TRAPS) {
3430 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
3431
3432 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3433
3434 JavaValue result(T_INT);
3435 JavaCallArguments args;
3436 args.push_int(DisplayVMOutputToStderr);
3437 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3438 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3439 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3440 if (result.get_jint() != JNI_OK) {
3441 vm_exit_during_initialization(); // no message or exception
3442 }
3443
3444 universe_post_module_init();
3445 }
3446
3447 // Phase 3. final setup - set security manager, system class loader and TCCL
3448 //
3449 // This will instantiate and set the security manager, set the system class
3450 // loader as well as the thread context class loader. The security manager
3451 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3452 // other modules or the application's classpath.
3453 static void call_initPhase3(TRAPS) {
3454 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3455 JavaValue result(T_VOID);
3456 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3457 vmSymbols::void_method_signature(), CHECK);
3458 }
3459
3460 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3461 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3462
3463 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3464 create_vm_init_libraries();
3465 }
3466
3467 initialize_class(vmSymbols::java_lang_String(), CHECK);
3468
3469 // Inject CompactStrings value after the static initializers for String ran.
3470 java_lang_String::set_compact_strings(CompactStrings);
3471
3472 // Initialize java_lang.System (needed before creating the thread)
3473 initialize_class(vmSymbols::java_lang_System(), CHECK);
3474 // The VM creates & returns objects of this class. Make sure it's initialized.
3475 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3476 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3477 Handle thread_group = create_initial_thread_group(CHECK);
3478 Universe::set_main_thread_group(thread_group());
3479 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3480 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3481 main_thread->set_threadObj(thread_object);
3482 // Set thread status to running since main thread has
3483 // been started and running.
3484 java_lang_Thread::set_thread_status(thread_object,
3485 java_lang_Thread::RUNNABLE);
3486
3487 // The VM creates objects of this class.
3488 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3489
3490 // The VM preresolves methods to these classes. Make sure that they get initialized
3491 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3492 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3493
3494 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3495 call_initPhase1(CHECK);
3496
3497 // get the Java runtime name after java.lang.System is initialized
3498 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3499 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3500
3501 // an instance of OutOfMemory exception has been allocated earlier
3502 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3503 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3504 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3505 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3506 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3507 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3508 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3509 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3510 }
3511
3512 void Threads::initialize_jsr292_core_classes(TRAPS) {
3513 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3514
3515 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3516 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3517 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3518 }
3519
3520 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3521 extern void JDK_Version_init();
3522
3523 // Preinitialize version info.
3524 VM_Version::early_initialize();
3525
3526 // Check version
3527 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3528
3529 // Initialize library-based TLS
3530 ThreadLocalStorage::init();
3531
3532 // Initialize the output stream module
3533 ostream_init();
3534
3535 // Process java launcher properties.
3536 Arguments::process_sun_java_launcher_properties(args);
3537
3538 // Initialize the os module
3539 os::init();
3540
3541 // Record VM creation timing statistics
3542 TraceVmCreationTime create_vm_timer;
3543 create_vm_timer.start();
3544
3545 // Initialize system properties.
3546 Arguments::init_system_properties();
3547
3548 // So that JDK version can be used as a discriminator when parsing arguments
3549 JDK_Version_init();
3550
3551 // Update/Initialize System properties after JDK version number is known
3552 Arguments::init_version_specific_system_properties();
3553
3554 // Make sure to initialize log configuration *before* parsing arguments
3555 LogConfiguration::initialize(create_vm_timer.begin_time());
3556
3557 // Parse arguments
3558 jint parse_result = Arguments::parse(args);
3559 if (parse_result != JNI_OK) return parse_result;
3560
3561 os::init_before_ergo();
3562
3563 jint ergo_result = Arguments::apply_ergo();
3564 if (ergo_result != JNI_OK) return ergo_result;
3565
3566 // Final check of all ranges after ergonomics which may change values.
3567 if (!CommandLineFlagRangeList::check_ranges()) {
3568 return JNI_EINVAL;
3569 }
3570
3571 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3572 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3573 if (!constraint_result) {
3574 return JNI_EINVAL;
3575 }
3576
3577 CommandLineFlagWriteableList::mark_startup();
3578
3579 if (PauseAtStartup) {
3580 os::pause();
3581 }
3582
3583 HOTSPOT_VM_INIT_BEGIN();
3584
3585 // Timing (must come after argument parsing)
3586 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3587
3588 // Initialize the os module after parsing the args
3589 jint os_init_2_result = os::init_2();
3590 if (os_init_2_result != JNI_OK) return os_init_2_result;
3591
3592 jint adjust_after_os_result = Arguments::adjust_after_os();
3593 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3594
3595 // Initialize output stream logging
3596 ostream_init_log();
3597
3598 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3599 // Must be before create_vm_init_agents()
3600 if (Arguments::init_libraries_at_startup()) {
3601 convert_vm_init_libraries_to_agents();
3602 }
3603
3604 // Launch -agentlib/-agentpath and converted -Xrun agents
3605 if (Arguments::init_agents_at_startup()) {
3606 create_vm_init_agents();
3607 }
3608
3609 // Initialize Threads state
3610 _thread_list = NULL;
3611 _number_of_threads = 0;
3612 _number_of_non_daemon_threads = 0;
3613
3614 // Initialize global data structures and create system classes in heap
3615 vm_init_globals();
3616
3617 #if INCLUDE_JVMCI
3618 if (JVMCICounterSize > 0) {
3619 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3620 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3621 } else {
3622 JavaThread::_jvmci_old_thread_counters = NULL;
3623 }
3624 #endif // INCLUDE_JVMCI
3625
3626 // Attach the main thread to this os thread
3627 JavaThread* main_thread = new JavaThread();
3628 main_thread->set_thread_state(_thread_in_vm);
3629 main_thread->initialize_thread_current();
3630 // must do this before set_active_handles
3631 main_thread->record_stack_base_and_size();
3632 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3633
3634 if (!main_thread->set_as_starting_thread()) {
3635 vm_shutdown_during_initialization(
3636 "Failed necessary internal allocation. Out of swap space");
3637 delete main_thread;
3638 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3639 return JNI_ENOMEM;
3640 }
3641
3642 // Enable guard page *after* os::create_main_thread(), otherwise it would
3643 // crash Linux VM, see notes in os_linux.cpp.
3644 main_thread->create_stack_guard_pages();
3645
3646 // Initialize Java-Level synchronization subsystem
3647 ObjectMonitor::Initialize();
3648
3649 // Initialize global modules
3650 jint status = init_globals();
3651 if (status != JNI_OK) {
3652 delete main_thread;
3653 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3654 return status;
3655 }
3656
3657 if (TRACE_INITIALIZE() != JNI_OK) {
3658 vm_exit_during_initialization("Failed to initialize tracing backend");
3659 }
3660
3661 // Should be done after the heap is fully created
3662 main_thread->cache_global_variables();
3663
3664 HandleMark hm;
3665
3666 { MutexLocker mu(Threads_lock);
3667 Threads::add(main_thread);
3668 }
3669
3670 // Any JVMTI raw monitors entered in onload will transition into
3671 // real raw monitor. VM is setup enough here for raw monitor enter.
3672 JvmtiExport::transition_pending_onload_raw_monitors();
3673
3674 // Create the VMThread
3675 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3676
3677 VMThread::create();
3678 Thread* vmthread = VMThread::vm_thread();
3679
3680 if (!os::create_thread(vmthread, os::vm_thread)) {
3681 vm_exit_during_initialization("Cannot create VM thread. "
3682 "Out of system resources.");
3683 }
3684
3685 // Wait for the VM thread to become ready, and VMThread::run to initialize
3686 // Monitors can have spurious returns, must always check another state flag
3687 {
3688 MutexLocker ml(Notify_lock);
3689 os::start_thread(vmthread);
3690 while (vmthread->active_handles() == NULL) {
3691 Notify_lock->wait();
3692 }
3693 }
3694 }
3695
3696 assert(Universe::is_fully_initialized(), "not initialized");
3697 if (VerifyDuringStartup) {
3698 // Make sure we're starting with a clean slate.
3699 VM_Verify verify_op;
3700 VMThread::execute(&verify_op);
3701 }
3702
3703 Thread* THREAD = Thread::current();
3704
3705 // At this point, the Universe is initialized, but we have not executed
3706 // any byte code. Now is a good time (the only time) to dump out the
3707 // internal state of the JVM for sharing.
3708 if (DumpSharedSpaces) {
3709 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3710 ShouldNotReachHere();
3711 }
3712
3713 // Always call even when there are not JVMTI environments yet, since environments
3714 // may be attached late and JVMTI must track phases of VM execution
3715 JvmtiExport::enter_early_start_phase();
3716
3717 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3718 JvmtiExport::post_early_vm_start();
3719
3720 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3721
3722 // We need this for ClassDataSharing - the initial vm.info property is set
3723 // with the default value of CDS "sharing" which may be reset through
3724 // command line options.
3725 reset_vm_info_property(CHECK_JNI_ERR);
3726
3727 quicken_jni_functions();
3728
3729 // No more stub generation allowed after that point.
3730 StubCodeDesc::freeze();
3731
3732 // Set flag that basic initialization has completed. Used by exceptions and various
3733 // debug stuff, that does not work until all basic classes have been initialized.
3734 set_init_completed();
3735
3736 LogConfiguration::post_initialize();
3737 Metaspace::post_initialize();
3738
3739 HOTSPOT_VM_INIT_END();
3740
3741 // record VM initialization completion time
3742 #if INCLUDE_MANAGEMENT
3743 Management::record_vm_init_completed();
3744 #endif // INCLUDE_MANAGEMENT
3745
3746 // Signal Dispatcher needs to be started before VMInit event is posted
3747 os::signal_init(CHECK_JNI_ERR);
3748
3749 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3750 if (!DisableAttachMechanism) {
3751 AttachListener::vm_start();
3752 if (StartAttachListener || AttachListener::init_at_startup()) {
3753 AttachListener::init();
3754 }
3755 }
3756
3757 // Launch -Xrun agents
3758 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3759 // back-end can launch with -Xdebug -Xrunjdwp.
3760 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3761 create_vm_init_libraries();
3762 }
3763
3764 if (CleanChunkPoolAsync) {
3765 Chunk::start_chunk_pool_cleaner_task();
3766 }
3767
3768 // initialize compiler(s)
3769 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3770 CompileBroker::compilation_init(CHECK_JNI_ERR);
3771 #endif
3772
3773 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3774 // It is done after compilers are initialized, because otherwise compilations of
3775 // signature polymorphic MH intrinsics can be missed
3776 // (see SystemDictionary::find_method_handle_intrinsic).
3777 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3778
3779 // This will initialize the module system. Only java.base classes can be
3780 // loaded until phase 2 completes
3781 call_initPhase2(CHECK_JNI_ERR);
3782
3783 // Always call even when there are not JVMTI environments yet, since environments
3784 // may be attached late and JVMTI must track phases of VM execution
3785 JvmtiExport::enter_start_phase();
3786
3787 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3788 JvmtiExport::post_vm_start();
3789
3790 // Final system initialization including security manager and system class loader
3791 call_initPhase3(CHECK_JNI_ERR);
3792
3793 // cache the system class loader
3794 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3795
3796 #if INCLUDE_JVMCI
3797 if (EnableJVMCI) {
3798 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3799 // The JVMCI Java initialization code will read this flag and
3800 // do the printing if it's set.
3801 bool init = JVMCIPrintProperties;
3802
3803 if (!init) {
3804 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3805 // compilations via JVMCI will not actually block until JVMCI is initialized.
3806 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3807 }
3808
3809 if (init) {
3810 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3811 }
3812 }
3813 #endif
3814
3815 // Always call even when there are not JVMTI environments yet, since environments
3816 // may be attached late and JVMTI must track phases of VM execution
3817 JvmtiExport::enter_live_phase();
3818
3819 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3820 JvmtiExport::post_vm_initialized();
3821
3822 if (TRACE_START() != JNI_OK) {
3823 vm_exit_during_initialization("Failed to start tracing backend.");
3824 }
3825
3826 #if INCLUDE_MANAGEMENT
3827 Management::initialize(THREAD);
3828
3829 if (HAS_PENDING_EXCEPTION) {
3830 // management agent fails to start possibly due to
3831 // configuration problem and is responsible for printing
3832 // stack trace if appropriate. Simply exit VM.
3833 vm_exit(1);
3834 }
3835 #endif // INCLUDE_MANAGEMENT
3836
3837 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3838 if (MemProfiling) MemProfiler::engage();
3839 StatSampler::engage();
3840 if (CheckJNICalls) JniPeriodicChecker::engage();
3841
3842 BiasedLocking::init();
3843
3844 #if INCLUDE_RTM_OPT
3845 RTMLockingCounters::init();
3846 #endif
3847
3848 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3849 call_postVMInitHook(THREAD);
3850 // The Java side of PostVMInitHook.run must deal with all
3851 // exceptions and provide means of diagnosis.
3852 if (HAS_PENDING_EXCEPTION) {
3853 CLEAR_PENDING_EXCEPTION;
3854 }
3855 }
3856
3857 {
3858 MutexLocker ml(PeriodicTask_lock);
3859 // Make sure the WatcherThread can be started by WatcherThread::start()
3860 // or by dynamic enrollment.
3861 WatcherThread::make_startable();
3862 // Start up the WatcherThread if there are any periodic tasks
3863 // NOTE: All PeriodicTasks should be registered by now. If they
3864 // aren't, late joiners might appear to start slowly (we might
3865 // take a while to process their first tick).
3866 if (PeriodicTask::num_tasks() > 0) {
3867 WatcherThread::start();
3868 }
3869 }
3870
3871 create_vm_timer.end();
3872 #ifdef ASSERT
3873 _vm_complete = true;
3874 #endif
3875 return JNI_OK;
3876 }
3877
3878 // type for the Agent_OnLoad and JVM_OnLoad entry points
3879 extern "C" {
3880 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3881 }
3882 // Find a command line agent library and return its entry point for
3883 // -agentlib: -agentpath: -Xrun
3884 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3885 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3886 const char *on_load_symbols[],
3887 size_t num_symbol_entries) {
3888 OnLoadEntry_t on_load_entry = NULL;
3889 void *library = NULL;
3890
3891 if (!agent->valid()) {
3892 char buffer[JVM_MAXPATHLEN];
3893 char ebuf[1024] = "";
3894 const char *name = agent->name();
3895 const char *msg = "Could not find agent library ";
3896
3897 // First check to see if agent is statically linked into executable
3898 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3899 library = agent->os_lib();
3900 } else if (agent->is_absolute_path()) {
3901 library = os::dll_load(name, ebuf, sizeof ebuf);
3902 if (library == NULL) {
3903 const char *sub_msg = " in absolute path, with error: ";
3904 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3905 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3906 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3907 // If we can't find the agent, exit.
3908 vm_exit_during_initialization(buf, NULL);
3909 FREE_C_HEAP_ARRAY(char, buf);
3910 }
3911 } else {
3912 // Try to load the agent from the standard dll directory
3913 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3914 name)) {
3915 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3916 }
3917 if (library == NULL) { // Try the local directory
3918 char ns[1] = {0};
3919 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3920 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3921 }
3922 if (library == NULL) {
3923 const char *sub_msg = " on the library path, with error: ";
3924 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3925 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3926 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3927 // If we can't find the agent, exit.
3928 vm_exit_during_initialization(buf, NULL);
3929 FREE_C_HEAP_ARRAY(char, buf);
3930 }
3931 }
3932 }
3933 agent->set_os_lib(library);
3934 agent->set_valid();
3935 }
3936
3937 // Find the OnLoad function.
3938 on_load_entry =
3939 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3940 false,
3941 on_load_symbols,
3942 num_symbol_entries));
3943 return on_load_entry;
3944 }
3945
3946 // Find the JVM_OnLoad entry point
3947 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3948 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3949 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3950 }
3951
3952 // Find the Agent_OnLoad entry point
3953 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3954 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3955 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3956 }
3957
3958 // For backwards compatibility with -Xrun
3959 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3960 // treated like -agentpath:
3961 // Must be called before agent libraries are created
3962 void Threads::convert_vm_init_libraries_to_agents() {
3963 AgentLibrary* agent;
3964 AgentLibrary* next;
3965
3966 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3967 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3968 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3969
3970 // If there is an JVM_OnLoad function it will get called later,
3971 // otherwise see if there is an Agent_OnLoad
3972 if (on_load_entry == NULL) {
3973 on_load_entry = lookup_agent_on_load(agent);
3974 if (on_load_entry != NULL) {
3975 // switch it to the agent list -- so that Agent_OnLoad will be called,
3976 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3977 Arguments::convert_library_to_agent(agent);
3978 } else {
3979 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3980 }
3981 }
3982 }
3983 }
3984
3985 // Create agents for -agentlib: -agentpath: and converted -Xrun
3986 // Invokes Agent_OnLoad
3987 // Called very early -- before JavaThreads exist
3988 void Threads::create_vm_init_agents() {
3989 extern struct JavaVM_ main_vm;
3990 AgentLibrary* agent;
3991
3992 JvmtiExport::enter_onload_phase();
3993
3994 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3995 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3996
3997 if (on_load_entry != NULL) {
3998 // Invoke the Agent_OnLoad function
3999 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4000 if (err != JNI_OK) {
4001 vm_exit_during_initialization("agent library failed to init", agent->name());
4002 }
4003 } else {
4004 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4005 }
4006 }
4007 JvmtiExport::enter_primordial_phase();
4008 }
4009
4010 extern "C" {
4011 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4012 }
4013
4014 void Threads::shutdown_vm_agents() {
4015 // Send any Agent_OnUnload notifications
4016 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4017 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4018 extern struct JavaVM_ main_vm;
4019 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4020
4021 // Find the Agent_OnUnload function.
4022 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4023 os::find_agent_function(agent,
4024 false,
4025 on_unload_symbols,
4026 num_symbol_entries));
4027
4028 // Invoke the Agent_OnUnload function
4029 if (unload_entry != NULL) {
4030 JavaThread* thread = JavaThread::current();
4031 ThreadToNativeFromVM ttn(thread);
4032 HandleMark hm(thread);
4033 (*unload_entry)(&main_vm);
4034 }
4035 }
4036 }
4037
4038 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4039 // Invokes JVM_OnLoad
4040 void Threads::create_vm_init_libraries() {
4041 extern struct JavaVM_ main_vm;
4042 AgentLibrary* agent;
4043
4044 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4045 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4046
4047 if (on_load_entry != NULL) {
4048 // Invoke the JVM_OnLoad function
4049 JavaThread* thread = JavaThread::current();
4050 ThreadToNativeFromVM ttn(thread);
4051 HandleMark hm(thread);
4052 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4053 if (err != JNI_OK) {
4054 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4055 }
4056 } else {
4057 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4058 }
4059 }
4060 }
4061
4062 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4063 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4064
4065 JavaThread* java_thread = NULL;
4066 // Sequential search for now. Need to do better optimization later.
4067 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4068 oop tobj = thread->threadObj();
4069 if (!thread->is_exiting() &&
4070 tobj != NULL &&
4071 java_tid == java_lang_Thread::thread_id(tobj)) {
4072 java_thread = thread;
4073 break;
4074 }
4075 }
4076 return java_thread;
4077 }
4078
4079
4080 // Last thread running calls java.lang.Shutdown.shutdown()
4081 void JavaThread::invoke_shutdown_hooks() {
4082 HandleMark hm(this);
4083
4084 // We could get here with a pending exception, if so clear it now.
4085 if (this->has_pending_exception()) {
4086 this->clear_pending_exception();
4087 }
4088
4089 EXCEPTION_MARK;
4090 Klass* shutdown_klass =
4091 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4092 THREAD);
4093 if (shutdown_klass != NULL) {
4094 // SystemDictionary::resolve_or_null will return null if there was
4095 // an exception. If we cannot load the Shutdown class, just don't
4096 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4097 // and finalizers (if runFinalizersOnExit is set) won't be run.
4098 // Note that if a shutdown hook was registered or runFinalizersOnExit
4099 // was called, the Shutdown class would have already been loaded
4100 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4101 JavaValue result(T_VOID);
4102 JavaCalls::call_static(&result,
4103 shutdown_klass,
4104 vmSymbols::shutdown_method_name(),
4105 vmSymbols::void_method_signature(),
4106 THREAD);
4107 }
4108 CLEAR_PENDING_EXCEPTION;
4109 }
4110
4111 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4112 // the program falls off the end of main(). Another VM exit path is through
4113 // vm_exit() when the program calls System.exit() to return a value or when
4114 // there is a serious error in VM. The two shutdown paths are not exactly
4115 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4116 // and VM_Exit op at VM level.
4117 //
4118 // Shutdown sequence:
4119 // + Shutdown native memory tracking if it is on
4120 // + Wait until we are the last non-daemon thread to execute
4121 // <-- every thing is still working at this moment -->
4122 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4123 // shutdown hooks, run finalizers if finalization-on-exit
4124 // + Call before_exit(), prepare for VM exit
4125 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4126 // currently the only user of this mechanism is File.deleteOnExit())
4127 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4128 // post thread end and vm death events to JVMTI,
4129 // stop signal thread
4130 // + Call JavaThread::exit(), it will:
4131 // > release JNI handle blocks, remove stack guard pages
4132 // > remove this thread from Threads list
4133 // <-- no more Java code from this thread after this point -->
4134 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4135 // the compiler threads at safepoint
4136 // <-- do not use anything that could get blocked by Safepoint -->
4137 // + Disable tracing at JNI/JVM barriers
4138 // + Set _vm_exited flag for threads that are still running native code
4139 // + Delete this thread
4140 // + Call exit_globals()
4141 // > deletes tty
4142 // > deletes PerfMemory resources
4143 // + Return to caller
4144
4145 bool Threads::destroy_vm() {
4146 JavaThread* thread = JavaThread::current();
4147
4148 #ifdef ASSERT
4149 _vm_complete = false;
4150 #endif
4151 // Wait until we are the last non-daemon thread to execute
4152 { MutexLocker nu(Threads_lock);
4153 while (Threads::number_of_non_daemon_threads() > 1)
4154 // This wait should make safepoint checks, wait without a timeout,
4155 // and wait as a suspend-equivalent condition.
4156 //
4157 // Note: If the FlatProfiler is running and this thread is waiting
4158 // for another non-daemon thread to finish, then the FlatProfiler
4159 // is waiting for the external suspend request on this thread to
4160 // complete. wait_for_ext_suspend_completion() will eventually
4161 // timeout, but that takes time. Making this wait a suspend-
4162 // equivalent condition solves that timeout problem.
4163 //
4164 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4165 Mutex::_as_suspend_equivalent_flag);
4166 }
4167
4168 // Hang forever on exit if we are reporting an error.
4169 if (ShowMessageBoxOnError && is_error_reported()) {
4170 os::infinite_sleep();
4171 }
4172 os::wait_for_keypress_at_exit();
4173
4174 // run Java level shutdown hooks
4175 thread->invoke_shutdown_hooks();
4176
4177 before_exit(thread);
4178
4179 thread->exit(true);
4180
4181 // Stop VM thread.
4182 {
4183 // 4945125 The vm thread comes to a safepoint during exit.
4184 // GC vm_operations can get caught at the safepoint, and the
4185 // heap is unparseable if they are caught. Grab the Heap_lock
4186 // to prevent this. The GC vm_operations will not be able to
4187 // queue until after the vm thread is dead. After this point,
4188 // we'll never emerge out of the safepoint before the VM exits.
4189
4190 MutexLocker ml(Heap_lock);
4191
4192 VMThread::wait_for_vm_thread_exit();
4193 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4194 VMThread::destroy();
4195 }
4196
4197 // clean up ideal graph printers
4198 #if defined(COMPILER2) && !defined(PRODUCT)
4199 IdealGraphPrinter::clean_up();
4200 #endif
4201
4202 // Now, all Java threads are gone except daemon threads. Daemon threads
4203 // running Java code or in VM are stopped by the Safepoint. However,
4204 // daemon threads executing native code are still running. But they
4205 // will be stopped at native=>Java/VM barriers. Note that we can't
4206 // simply kill or suspend them, as it is inherently deadlock-prone.
4207
4208 VM_Exit::set_vm_exited();
4209
4210 notify_vm_shutdown();
4211
4212 delete thread;
4213
4214 #if INCLUDE_JVMCI
4215 if (JVMCICounterSize > 0) {
4216 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4217 }
4218 #endif
4219
4220 // exit_globals() will delete tty
4221 exit_globals();
4222
4223 LogConfiguration::finalize();
4224
4225 return true;
4226 }
4227
4228
4229 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4230 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4231 return is_supported_jni_version(version);
4232 }
4233
4234
4235 jboolean Threads::is_supported_jni_version(jint version) {
4236 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4237 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4238 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4239 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4240 if (version == JNI_VERSION_9) return JNI_TRUE;
4241 return JNI_FALSE;
4242 }
4243
4244
4245 void Threads::add(JavaThread* p, bool force_daemon) {
4246 // The threads lock must be owned at this point
4247 assert_locked_or_safepoint(Threads_lock);
4248
4249 // See the comment for this method in thread.hpp for its purpose and
4250 // why it is called here.
4251 p->initialize_queues();
4252 p->set_next(_thread_list);
4253 _thread_list = p;
4254 _number_of_threads++;
4255 oop threadObj = p->threadObj();
4256 bool daemon = true;
4257 // Bootstrapping problem: threadObj can be null for initial
4258 // JavaThread (or for threads attached via JNI)
4259 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4260 _number_of_non_daemon_threads++;
4261 daemon = false;
4262 }
4263
4264 ThreadService::add_thread(p, daemon);
4265
4266 // Possible GC point.
4267 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4268 }
4269
4270 void Threads::remove(JavaThread* p) {
4271 // Extra scope needed for Thread_lock, so we can check
4272 // that we do not remove thread without safepoint code notice
4273 { MutexLocker ml(Threads_lock);
4274
4275 assert(includes(p), "p must be present");
4276
4277 JavaThread* current = _thread_list;
4278 JavaThread* prev = NULL;
4279
4280 while (current != p) {
4281 prev = current;
4282 current = current->next();
4283 }
4284
4285 if (prev) {
4286 prev->set_next(current->next());
4287 } else {
4288 _thread_list = p->next();
4289 }
4290 _number_of_threads--;
4291 oop threadObj = p->threadObj();
4292 bool daemon = true;
4293 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4294 _number_of_non_daemon_threads--;
4295 daemon = false;
4296
4297 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4298 // on destroy_vm will wake up.
4299 if (number_of_non_daemon_threads() == 1) {
4300 Threads_lock->notify_all();
4301 }
4302 }
4303 ThreadService::remove_thread(p, daemon);
4304
4305 // Make sure that safepoint code disregard this thread. This is needed since
4306 // the thread might mess around with locks after this point. This can cause it
4307 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4308 // of this thread since it is removed from the queue.
4309 p->set_terminated_value();
4310 } // unlock Threads_lock
4311
4312 // Since Events::log uses a lock, we grab it outside the Threads_lock
4313 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4314 }
4315
4316 // Threads_lock must be held when this is called (or must be called during a safepoint)
4317 bool Threads::includes(JavaThread* p) {
4318 assert(Threads_lock->is_locked(), "sanity check");
4319 ALL_JAVA_THREADS(q) {
4320 if (q == p) {
4321 return true;
4322 }
4323 }
4324 return false;
4325 }
4326
4327 // Operations on the Threads list for GC. These are not explicitly locked,
4328 // but the garbage collector must provide a safe context for them to run.
4329 // In particular, these things should never be called when the Threads_lock
4330 // is held by some other thread. (Note: the Safepoint abstraction also
4331 // uses the Threads_lock to guarantee this property. It also makes sure that
4332 // all threads gets blocked when exiting or starting).
4333
4334 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4335 ALL_JAVA_THREADS(p) {
4336 p->oops_do(f, cf);
4337 }
4338 VMThread::vm_thread()->oops_do(f, cf);
4339 }
4340
4341 void Threads::change_thread_claim_parity() {
4342 // Set the new claim parity.
4343 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4344 "Not in range.");
4345 _thread_claim_parity++;
4346 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4347 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4348 "Not in range.");
4349 }
4350
4351 #ifdef ASSERT
4352 void Threads::assert_all_threads_claimed() {
4353 ALL_JAVA_THREADS(p) {
4354 const int thread_parity = p->oops_do_parity();
4355 assert((thread_parity == _thread_claim_parity),
4356 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4357 }
4358 }
4359 #endif // ASSERT
4360
4361 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4362 int cp = Threads::thread_claim_parity();
4363 ALL_JAVA_THREADS(p) {
4364 if (p->claim_oops_do(is_par, cp)) {
4365 p->oops_do(f, cf);
4366 }
4367 }
4368 VMThread* vmt = VMThread::vm_thread();
4369 if (vmt->claim_oops_do(is_par, cp)) {
4370 vmt->oops_do(f, cf);
4371 }
4372 }
4373
4374 #if INCLUDE_ALL_GCS
4375 // Used by ParallelScavenge
4376 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4377 ALL_JAVA_THREADS(p) {
4378 q->enqueue(new ThreadRootsTask(p));
4379 }
4380 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4381 }
4382
4383 // Used by Parallel Old
4384 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4385 ALL_JAVA_THREADS(p) {
4386 q->enqueue(new ThreadRootsMarkingTask(p));
4387 }
4388 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4389 }
4390 #endif // INCLUDE_ALL_GCS
4391
4392 void Threads::nmethods_do(CodeBlobClosure* cf) {
4393 ALL_JAVA_THREADS(p) {
4394 // This is used by the code cache sweeper to mark nmethods that are active
4395 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4396 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4397 if(!p->is_Code_cache_sweeper_thread()) {
4398 p->nmethods_do(cf);
4399 }
4400 }
4401 }
4402
4403 void Threads::metadata_do(void f(Metadata*)) {
4404 ALL_JAVA_THREADS(p) {
4405 p->metadata_do(f);
4406 }
4407 }
4408
4409 class ThreadHandlesClosure : public ThreadClosure {
4410 void (*_f)(Metadata*);
4411 public:
4412 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4413 virtual void do_thread(Thread* thread) {
4414 thread->metadata_handles_do(_f);
4415 }
4416 };
4417
4418 void Threads::metadata_handles_do(void f(Metadata*)) {
4419 // Only walk the Handles in Thread.
4420 ThreadHandlesClosure handles_closure(f);
4421 threads_do(&handles_closure);
4422 }
4423
4424 void Threads::deoptimized_wrt_marked_nmethods() {
4425 ALL_JAVA_THREADS(p) {
4426 p->deoptimized_wrt_marked_nmethods();
4427 }
4428 }
4429
4430
4431 // Get count Java threads that are waiting to enter the specified monitor.
4432 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4433 address monitor,
4434 bool doLock) {
4435 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4436 "must grab Threads_lock or be at safepoint");
4437 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4438
4439 int i = 0;
4440 {
4441 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4442 ALL_JAVA_THREADS(p) {
4443 if (!p->can_call_java()) continue;
4444
4445 address pending = (address)p->current_pending_monitor();
4446 if (pending == monitor) { // found a match
4447 if (i < count) result->append(p); // save the first count matches
4448 i++;
4449 }
4450 }
4451 }
4452 return result;
4453 }
4454
4455
4456 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4457 bool doLock) {
4458 assert(doLock ||
4459 Threads_lock->owned_by_self() ||
4460 SafepointSynchronize::is_at_safepoint(),
4461 "must grab Threads_lock or be at safepoint");
4462
4463 // NULL owner means not locked so we can skip the search
4464 if (owner == NULL) return NULL;
4465
4466 {
4467 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4468 ALL_JAVA_THREADS(p) {
4469 // first, see if owner is the address of a Java thread
4470 if (owner == (address)p) return p;
4471 }
4472 }
4473 // Cannot assert on lack of success here since this function may be
4474 // used by code that is trying to report useful problem information
4475 // like deadlock detection.
4476 if (UseHeavyMonitors) return NULL;
4477
4478 // If we didn't find a matching Java thread and we didn't force use of
4479 // heavyweight monitors, then the owner is the stack address of the
4480 // Lock Word in the owning Java thread's stack.
4481 //
4482 JavaThread* the_owner = NULL;
4483 {
4484 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4485 ALL_JAVA_THREADS(q) {
4486 if (q->is_lock_owned(owner)) {
4487 the_owner = q;
4488 break;
4489 }
4490 }
4491 }
4492 // cannot assert on lack of success here; see above comment
4493 return the_owner;
4494 }
4495
4496 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4497 void Threads::print_on(outputStream* st, bool print_stacks,
4498 bool internal_format, bool print_concurrent_locks) {
4499 char buf[32];
4500 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4501
4502 st->print_cr("Full thread dump %s (%s %s):",
4503 Abstract_VM_Version::vm_name(),
4504 Abstract_VM_Version::vm_release(),
4505 Abstract_VM_Version::vm_info_string());
4506 st->cr();
4507
4508 #if INCLUDE_SERVICES
4509 // Dump concurrent locks
4510 ConcurrentLocksDump concurrent_locks;
4511 if (print_concurrent_locks) {
4512 concurrent_locks.dump_at_safepoint();
4513 }
4514 #endif // INCLUDE_SERVICES
4515
4516 ALL_JAVA_THREADS(p) {
4517 ResourceMark rm;
4518 p->print_on(st);
4519 if (print_stacks) {
4520 if (internal_format) {
4521 p->trace_stack();
4522 } else {
4523 p->print_stack_on(st);
4524 }
4525 }
4526 st->cr();
4527 #if INCLUDE_SERVICES
4528 if (print_concurrent_locks) {
4529 concurrent_locks.print_locks_on(p, st);
4530 }
4531 #endif // INCLUDE_SERVICES
4532 }
4533
4534 VMThread::vm_thread()->print_on(st);
4535 st->cr();
4536 Universe::heap()->print_gc_threads_on(st);
4537 WatcherThread* wt = WatcherThread::watcher_thread();
4538 if (wt != NULL) {
4539 wt->print_on(st);
4540 st->cr();
4541 }
4542 st->flush();
4543 }
4544
4545 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4546 int buflen, bool* found_current) {
4547 if (this_thread != NULL) {
4548 bool is_current = (current == this_thread);
4549 *found_current = *found_current || is_current;
4550 st->print("%s", is_current ? "=>" : " ");
4551
4552 st->print(PTR_FORMAT, p2i(this_thread));
4553 st->print(" ");
4554 this_thread->print_on_error(st, buf, buflen);
4555 st->cr();
4556 }
4557 }
4558
4559 class PrintOnErrorClosure : public ThreadClosure {
4560 outputStream* _st;
4561 Thread* _current;
4562 char* _buf;
4563 int _buflen;
4564 bool* _found_current;
4565 public:
4566 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4567 int buflen, bool* found_current) :
4568 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4569
4570 virtual void do_thread(Thread* thread) {
4571 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4572 }
4573 };
4574
4575 // Threads::print_on_error() is called by fatal error handler. It's possible
4576 // that VM is not at safepoint and/or current thread is inside signal handler.
4577 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4578 // memory (even in resource area), it might deadlock the error handler.
4579 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4580 int buflen) {
4581 bool found_current = false;
4582 st->print_cr("Java Threads: ( => current thread )");
4583 ALL_JAVA_THREADS(thread) {
4584 print_on_error(thread, st, current, buf, buflen, &found_current);
4585 }
4586 st->cr();
4587
4588 st->print_cr("Other Threads:");
4589 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4590 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4591
4592 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4593 Universe::heap()->gc_threads_do(&print_closure);
4594
4595 if (!found_current) {
4596 st->cr();
4597 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4598 current->print_on_error(st, buf, buflen);
4599 st->cr();
4600 }
4601 st->cr();
4602 st->print_cr("Threads with active compile tasks:");
4603 print_threads_compiling(st, buf, buflen);
4604 }
4605
4606 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4607 ALL_JAVA_THREADS(thread) {
4608 if (thread->is_Compiler_thread()) {
4609 CompilerThread* ct = (CompilerThread*) thread;
4610 if (ct->task() != NULL) {
4611 thread->print_name_on_error(st, buf, buflen);
4612 ct->task()->print(st, NULL, true, true);
4613 }
4614 }
4615 }
4616 }
4617
4618
4619 // Internal SpinLock and Mutex
4620 // Based on ParkEvent
4621
4622 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4623 //
4624 // We employ SpinLocks _only for low-contention, fixed-length
4625 // short-duration critical sections where we're concerned
4626 // about native mutex_t or HotSpot Mutex:: latency.
4627 // The mux construct provides a spin-then-block mutual exclusion
4628 // mechanism.
4629 //
4630 // Testing has shown that contention on the ListLock guarding gFreeList
4631 // is common. If we implement ListLock as a simple SpinLock it's common
4632 // for the JVM to devolve to yielding with little progress. This is true
4633 // despite the fact that the critical sections protected by ListLock are
4634 // extremely short.
4635 //
4636 // TODO-FIXME: ListLock should be of type SpinLock.
4637 // We should make this a 1st-class type, integrated into the lock
4638 // hierarchy as leaf-locks. Critically, the SpinLock structure
4639 // should have sufficient padding to avoid false-sharing and excessive
4640 // cache-coherency traffic.
4641
4642
4643 typedef volatile int SpinLockT;
4644
4645 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4646 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4647 return; // normal fast-path return
4648 }
4649
4650 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4651 TEVENT(SpinAcquire - ctx);
4652 int ctr = 0;
4653 int Yields = 0;
4654 for (;;) {
4655 while (*adr != 0) {
4656 ++ctr;
4657 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4658 if (Yields > 5) {
4659 os::naked_short_sleep(1);
4660 } else {
4661 os::naked_yield();
4662 ++Yields;
4663 }
4664 } else {
4665 SpinPause();
4666 }
4667 }
4668 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4669 }
4670 }
4671
4672 void Thread::SpinRelease(volatile int * adr) {
4673 assert(*adr != 0, "invariant");
4674 OrderAccess::fence(); // guarantee at least release consistency.
4675 // Roach-motel semantics.
4676 // It's safe if subsequent LDs and STs float "up" into the critical section,
4677 // but prior LDs and STs within the critical section can't be allowed
4678 // to reorder or float past the ST that releases the lock.
4679 // Loads and stores in the critical section - which appear in program
4680 // order before the store that releases the lock - must also appear
4681 // before the store that releases the lock in memory visibility order.
4682 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4683 // the ST of 0 into the lock-word which releases the lock, so fence
4684 // more than covers this on all platforms.
4685 *adr = 0;
4686 }
4687
4688 // muxAcquire and muxRelease:
4689 //
4690 // * muxAcquire and muxRelease support a single-word lock-word construct.
4691 // The LSB of the word is set IFF the lock is held.
4692 // The remainder of the word points to the head of a singly-linked list
4693 // of threads blocked on the lock.
4694 //
4695 // * The current implementation of muxAcquire-muxRelease uses its own
4696 // dedicated Thread._MuxEvent instance. If we're interested in
4697 // minimizing the peak number of extant ParkEvent instances then
4698 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4699 // as certain invariants were satisfied. Specifically, care would need
4700 // to be taken with regards to consuming unpark() "permits".
4701 // A safe rule of thumb is that a thread would never call muxAcquire()
4702 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4703 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4704 // consume an unpark() permit intended for monitorenter, for instance.
4705 // One way around this would be to widen the restricted-range semaphore
4706 // implemented in park(). Another alternative would be to provide
4707 // multiple instances of the PlatformEvent() for each thread. One
4708 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4709 //
4710 // * Usage:
4711 // -- Only as leaf locks
4712 // -- for short-term locking only as muxAcquire does not perform
4713 // thread state transitions.
4714 //
4715 // Alternatives:
4716 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4717 // but with parking or spin-then-park instead of pure spinning.
4718 // * Use Taura-Oyama-Yonenzawa locks.
4719 // * It's possible to construct a 1-0 lock if we encode the lockword as
4720 // (List,LockByte). Acquire will CAS the full lockword while Release
4721 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4722 // acquiring threads use timers (ParkTimed) to detect and recover from
4723 // the stranding window. Thread/Node structures must be aligned on 256-byte
4724 // boundaries by using placement-new.
4725 // * Augment MCS with advisory back-link fields maintained with CAS().
4726 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4727 // The validity of the backlinks must be ratified before we trust the value.
4728 // If the backlinks are invalid the exiting thread must back-track through the
4729 // the forward links, which are always trustworthy.
4730 // * Add a successor indication. The LockWord is currently encoded as
4731 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4732 // to provide the usual futile-wakeup optimization.
4733 // See RTStt for details.
4734 // * Consider schedctl.sc_nopreempt to cover the critical section.
4735 //
4736
4737
4738 typedef volatile intptr_t MutexT; // Mux Lock-word
4739 enum MuxBits { LOCKBIT = 1 };
4740
4741 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4742 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4743 if (w == 0) return;
4744 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4745 return;
4746 }
4747
4748 TEVENT(muxAcquire - Contention);
4749 ParkEvent * const Self = Thread::current()->_MuxEvent;
4750 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4751 for (;;) {
4752 int its = (os::is_MP() ? 100 : 0) + 1;
4753
4754 // Optional spin phase: spin-then-park strategy
4755 while (--its >= 0) {
4756 w = *Lock;
4757 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4758 return;
4759 }
4760 }
4761
4762 Self->reset();
4763 Self->OnList = intptr_t(Lock);
4764 // The following fence() isn't _strictly necessary as the subsequent
4765 // CAS() both serializes execution and ratifies the fetched *Lock value.
4766 OrderAccess::fence();
4767 for (;;) {
4768 w = *Lock;
4769 if ((w & LOCKBIT) == 0) {
4770 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4771 Self->OnList = 0; // hygiene - allows stronger asserts
4772 return;
4773 }
4774 continue; // Interference -- *Lock changed -- Just retry
4775 }
4776 assert(w & LOCKBIT, "invariant");
4777 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4778 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4779 }
4780
4781 while (Self->OnList != 0) {
4782 Self->park();
4783 }
4784 }
4785 }
4786
4787 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4788 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4789 if (w == 0) return;
4790 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4791 return;
4792 }
4793
4794 TEVENT(muxAcquire - Contention);
4795 ParkEvent * ReleaseAfter = NULL;
4796 if (ev == NULL) {
4797 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4798 }
4799 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4800 for (;;) {
4801 guarantee(ev->OnList == 0, "invariant");
4802 int its = (os::is_MP() ? 100 : 0) + 1;
4803
4804 // Optional spin phase: spin-then-park strategy
4805 while (--its >= 0) {
4806 w = *Lock;
4807 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4808 if (ReleaseAfter != NULL) {
4809 ParkEvent::Release(ReleaseAfter);
4810 }
4811 return;
4812 }
4813 }
4814
4815 ev->reset();
4816 ev->OnList = intptr_t(Lock);
4817 // The following fence() isn't _strictly necessary as the subsequent
4818 // CAS() both serializes execution and ratifies the fetched *Lock value.
4819 OrderAccess::fence();
4820 for (;;) {
4821 w = *Lock;
4822 if ((w & LOCKBIT) == 0) {
4823 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4824 ev->OnList = 0;
4825 // We call ::Release while holding the outer lock, thus
4826 // artificially lengthening the critical section.
4827 // Consider deferring the ::Release() until the subsequent unlock(),
4828 // after we've dropped the outer lock.
4829 if (ReleaseAfter != NULL) {
4830 ParkEvent::Release(ReleaseAfter);
4831 }
4832 return;
4833 }
4834 continue; // Interference -- *Lock changed -- Just retry
4835 }
4836 assert(w & LOCKBIT, "invariant");
4837 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4838 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4839 }
4840
4841 while (ev->OnList != 0) {
4842 ev->park();
4843 }
4844 }
4845 }
4846
4847 // Release() must extract a successor from the list and then wake that thread.
4848 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4849 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4850 // Release() would :
4851 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4852 // (B) Extract a successor from the private list "in-hand"
4853 // (C) attempt to CAS() the residual back into *Lock over null.
4854 // If there were any newly arrived threads and the CAS() would fail.
4855 // In that case Release() would detach the RATs, re-merge the list in-hand
4856 // with the RATs and repeat as needed. Alternately, Release() might
4857 // detach and extract a successor, but then pass the residual list to the wakee.
4858 // The wakee would be responsible for reattaching and remerging before it
4859 // competed for the lock.
4860 //
4861 // Both "pop" and DMR are immune from ABA corruption -- there can be
4862 // multiple concurrent pushers, but only one popper or detacher.
4863 // This implementation pops from the head of the list. This is unfair,
4864 // but tends to provide excellent throughput as hot threads remain hot.
4865 // (We wake recently run threads first).
4866 //
4867 // All paths through muxRelease() will execute a CAS.
4868 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4869 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4870 // executed within the critical section are complete and globally visible before the
4871 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4872 void Thread::muxRelease(volatile intptr_t * Lock) {
4873 for (;;) {
4874 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4875 assert(w & LOCKBIT, "invariant");
4876 if (w == LOCKBIT) return;
4877 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4878 assert(List != NULL, "invariant");
4879 assert(List->OnList == intptr_t(Lock), "invariant");
4880 ParkEvent * const nxt = List->ListNext;
4881 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4882
4883 // The following CAS() releases the lock and pops the head element.
4884 // The CAS() also ratifies the previously fetched lock-word value.
4885 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4886 continue;
4887 }
4888 List->OnList = 0;
4889 OrderAccess::fence();
4890 List->unpark();
4891 return;
4892 }
4893 }
4894
4895
4896 void Threads::verify() {
4897 ALL_JAVA_THREADS(p) {
4898 p->verify();
4899 }
4900 VMThread* thread = VMThread::vm_thread();
4901 if (thread != NULL) thread->verify();
4902 }
4903
4904 void Threads::print_vt_buffer_stats_on(outputStream* st) {
4905 ALL_JAVA_THREADS(p) {
4906 p->print_vt_buffer_stats_on(st);
4907 }
4908 }