1 /*
2 * Copyright (c) 1997, 2011, 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/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/scopeDesc.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "interpreter/linkResolver.hpp"
34 #include "jvmtifiles/jvmtiEnv.hpp"
35 #include "memory/oopFactory.hpp"
36 #include "memory/universe.inline.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/objArrayOop.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "oops/symbol.hpp"
41 #include "prims/jvm_misc.hpp"
42 #include "prims/jvmtiExport.hpp"
43 #include "prims/jvmtiThreadState.hpp"
44 #include "prims/privilegedStack.hpp"
45 #include "runtime/aprofiler.hpp"
46 #include "runtime/arguments.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/deoptimization.hpp"
49 #include "runtime/fprofiler.hpp"
50 #include "runtime/frame.inline.hpp"
51 #include "runtime/init.hpp"
52 #include "runtime/interfaceSupport.hpp"
53 #include "runtime/java.hpp"
54 #include "runtime/javaCalls.hpp"
55 #include "runtime/jniPeriodicChecker.hpp"
56 #include "runtime/memprofiler.hpp"
57 #include "runtime/mutexLocker.hpp"
58 #include "runtime/objectMonitor.hpp"
59 #include "runtime/osThread.hpp"
60 #include "runtime/safepoint.hpp"
61 #include "runtime/sharedRuntime.hpp"
62 #include "runtime/statSampler.hpp"
63 #include "runtime/stubRoutines.hpp"
64 #include "runtime/task.hpp"
65 #include "runtime/threadCritical.hpp"
66 #include "runtime/threadLocalStorage.hpp"
67 #include "runtime/vframe.hpp"
68 #include "runtime/vframeArray.hpp"
69 #include "runtime/vframe_hp.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "runtime/vm_operations.hpp"
72 #include "services/attachListener.hpp"
73 #include "services/management.hpp"
74 #include "services/threadService.hpp"
75 #include "utilities/defaultStream.hpp"
76 #include "utilities/dtrace.hpp"
77 #include "utilities/events.hpp"
78 #include "utilities/preserveException.hpp"
79 #ifdef TARGET_OS_FAMILY_linux
80 # include "os_linux.inline.hpp"
81 # include "thread_linux.inline.hpp"
82 #endif
83 #ifdef TARGET_OS_FAMILY_solaris
84 # include "os_solaris.inline.hpp"
85 # include "thread_solaris.inline.hpp"
86 #endif
87 #ifdef TARGET_OS_FAMILY_windows
88 # include "os_windows.inline.hpp"
89 # include "thread_windows.inline.hpp"
90 #endif
91 #ifndef SERIALGC
92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
95 #endif
96 #ifdef COMPILER1
97 #include "c1/c1_Compiler.hpp"
98 #endif
99 #ifdef COMPILER2
100 #include "opto/c2compiler.hpp"
101 #include "opto/idealGraphPrinter.hpp"
102 #endif
103
104 #ifdef DTRACE_ENABLED
105
106 // Only bother with this argument setup if dtrace is available
107
108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
110 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
111 intptr_t, intptr_t, bool);
112 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
113 intptr_t, intptr_t, bool);
114
115 #define DTRACE_THREAD_PROBE(probe, javathread) \
116 { \
117 ResourceMark rm(this); \
118 int len = 0; \
119 const char* name = (javathread)->get_thread_name(); \
120 len = strlen(name); \
121 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
122 name, len, \
123 java_lang_Thread::thread_id((javathread)->threadObj()), \
124 (javathread)->osthread()->thread_id(), \
125 java_lang_Thread::is_daemon((javathread)->threadObj())); \
126 }
127
128 #else // ndef DTRACE_ENABLED
129
130 #define DTRACE_THREAD_PROBE(probe, javathread)
131
132 #endif // ndef DTRACE_ENABLED
133
134 // Class hierarchy
135 // - Thread
136 // - VMThread
137 // - WatcherThread
138 // - ConcurrentMarkSweepThread
139 // - JavaThread
140 // - CompilerThread
141
142 // ======= Thread ========
143
144 // Support for forcing alignment of thread objects for biased locking
145 void* Thread::operator new(size_t size) {
146 if (UseBiasedLocking) {
147 const int alignment = markOopDesc::biased_lock_alignment;
148 size_t aligned_size = size + (alignment - sizeof(intptr_t));
149 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
150 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
151 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
152 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
153 "JavaThread alignment code overflowed allocated storage");
154 if (TraceBiasedLocking) {
155 if (aligned_addr != real_malloc_addr)
156 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
157 real_malloc_addr, aligned_addr);
158 }
159 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
160 return aligned_addr;
161 } else {
162 return CHeapObj::operator new(size);
163 }
164 }
165
166 void Thread::operator delete(void* p) {
167 if (UseBiasedLocking) {
168 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
169 CHeapObj::operator delete(real_malloc_addr);
170 } else {
171 CHeapObj::operator delete(p);
172 }
173 }
174
175
176 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
177 // JavaThread
178
179
180 Thread::Thread() {
181 // stack and get_thread
182 set_stack_base(NULL);
183 set_stack_size(0);
184 set_self_raw_id(0);
185 set_lgrp_id(-1);
186
187 // allocated data structures
188 set_osthread(NULL);
189 set_resource_area(new ResourceArea());
190 set_handle_area(new HandleArea(NULL));
191 set_active_handles(NULL);
192 set_free_handle_block(NULL);
193 set_last_handle_mark(NULL);
194
195 // This initial value ==> never claimed.
196 _oops_do_parity = 0;
197
198 // the handle mark links itself to last_handle_mark
199 new HandleMark(this);
200
201 // plain initialization
202 debug_only(_owned_locks = NULL;)
203 debug_only(_allow_allocation_count = 0;)
204 NOT_PRODUCT(_allow_safepoint_count = 0;)
205 NOT_PRODUCT(_skip_gcalot = false;)
206 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
207 _jvmti_env_iteration_count = 0;
208 set_allocated_bytes(0);
209 _vm_operation_started_count = 0;
210 _vm_operation_completed_count = 0;
211 _current_pending_monitor = NULL;
212 _current_pending_monitor_is_from_java = true;
213 _current_waiting_monitor = NULL;
214 _num_nested_signal = 0;
215 omFreeList = NULL ;
216 omFreeCount = 0 ;
217 omFreeProvision = 32 ;
218 omInUseList = NULL ;
219 omInUseCount = 0 ;
220
221 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
222 _suspend_flags = 0;
223
224 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
225 _hashStateX = os::random() ;
226 _hashStateY = 842502087 ;
227 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
228 _hashStateW = 273326509 ;
229
230 _OnTrap = 0 ;
231 _schedctl = NULL ;
232 _Stalled = 0 ;
233 _TypeTag = 0x2BAD ;
234
235 // Many of the following fields are effectively final - immutable
236 // Note that nascent threads can't use the Native Monitor-Mutex
237 // construct until the _MutexEvent is initialized ...
238 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
239 // we might instead use a stack of ParkEvents that we could provision on-demand.
240 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
241 // and ::Release()
242 _ParkEvent = ParkEvent::Allocate (this) ;
243 _SleepEvent = ParkEvent::Allocate (this) ;
244 _MutexEvent = ParkEvent::Allocate (this) ;
245 _MuxEvent = ParkEvent::Allocate (this) ;
246
247 #ifdef CHECK_UNHANDLED_OOPS
248 if (CheckUnhandledOops) {
249 _unhandled_oops = new UnhandledOops(this);
250 }
251 #endif // CHECK_UNHANDLED_OOPS
252 #ifdef ASSERT
253 if (UseBiasedLocking) {
254 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
255 assert(this == _real_malloc_address ||
256 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
257 "bug in forced alignment of thread objects");
258 }
259 #endif /* ASSERT */
260 }
261
262 void Thread::initialize_thread_local_storage() {
263 // Note: Make sure this method only calls
264 // non-blocking operations. Otherwise, it might not work
265 // with the thread-startup/safepoint interaction.
266
267 // During Java thread startup, safepoint code should allow this
268 // method to complete because it may need to allocate memory to
269 // store information for the new thread.
270
271 // initialize structure dependent on thread local storage
272 ThreadLocalStorage::set_thread(this);
273
274 // set up any platform-specific state.
275 os::initialize_thread();
276
277 }
278
279 void Thread::record_stack_base_and_size() {
280 set_stack_base(os::current_stack_base());
281 set_stack_size(os::current_stack_size());
282 }
283
284
285 Thread::~Thread() {
286 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
287 ObjectSynchronizer::omFlush (this) ;
288
289 // deallocate data structures
290 delete resource_area();
291 // since the handle marks are using the handle area, we have to deallocated the root
292 // handle mark before deallocating the thread's handle area,
293 assert(last_handle_mark() != NULL, "check we have an element");
294 delete last_handle_mark();
295 assert(last_handle_mark() == NULL, "check we have reached the end");
296
297 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
298 // We NULL out the fields for good hygiene.
299 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
300 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
301 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
302 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
303
304 delete handle_area();
305
306 // osthread() can be NULL, if creation of thread failed.
307 if (osthread() != NULL) os::free_thread(osthread());
308
309 delete _SR_lock;
310
311 // clear thread local storage if the Thread is deleting itself
312 if (this == Thread::current()) {
313 ThreadLocalStorage::set_thread(NULL);
314 } else {
315 // In the case where we're not the current thread, invalidate all the
316 // caches in case some code tries to get the current thread or the
317 // thread that was destroyed, and gets stale information.
318 ThreadLocalStorage::invalidate_all();
319 }
320 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
321 }
322
323 // NOTE: dummy function for assertion purpose.
324 void Thread::run() {
325 ShouldNotReachHere();
326 }
327
328 #ifdef ASSERT
329 // Private method to check for dangling thread pointer
330 void check_for_dangling_thread_pointer(Thread *thread) {
331 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
332 "possibility of dangling Thread pointer");
333 }
334 #endif
335
336
337 #ifndef PRODUCT
338 // Tracing method for basic thread operations
339 void Thread::trace(const char* msg, const Thread* const thread) {
340 if (!TraceThreadEvents) return;
341 ResourceMark rm;
342 ThreadCritical tc;
343 const char *name = "non-Java thread";
344 int prio = -1;
345 if (thread->is_Java_thread()
346 && !thread->is_Compiler_thread()) {
347 // The Threads_lock must be held to get information about
348 // this thread but may not be in some situations when
349 // tracing thread events.
350 bool release_Threads_lock = false;
351 if (!Threads_lock->owned_by_self()) {
352 Threads_lock->lock();
353 release_Threads_lock = true;
354 }
355 JavaThread* jt = (JavaThread *)thread;
356 name = (char *)jt->get_thread_name();
357 oop thread_oop = jt->threadObj();
358 if (thread_oop != NULL) {
359 prio = java_lang_Thread::priority(thread_oop);
360 }
361 if (release_Threads_lock) {
362 Threads_lock->unlock();
363 }
364 }
365 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
366 }
367 #endif
368
369
370 ThreadPriority Thread::get_priority(const Thread* const thread) {
371 trace("get priority", thread);
372 ThreadPriority priority;
373 // Can return an error!
374 (void)os::get_priority(thread, priority);
375 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
376 return priority;
377 }
378
379 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
380 trace("set priority", thread);
381 debug_only(check_for_dangling_thread_pointer(thread);)
382 // Can return an error!
383 (void)os::set_priority(thread, priority);
384 }
385
386
387 void Thread::start(Thread* thread) {
388 trace("start", thread);
389 // Start is different from resume in that its safety is guaranteed by context or
390 // being called from a Java method synchronized on the Thread object.
391 if (!DisableStartThread) {
392 if (thread->is_Java_thread()) {
393 // Initialize the thread state to RUNNABLE before starting this thread.
394 // Can not set it after the thread started because we do not know the
395 // exact thread state at that time. It could be in MONITOR_WAIT or
396 // in SLEEPING or some other state.
397 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
398 java_lang_Thread::RUNNABLE);
399 }
400 os::start_thread(thread);
401 }
402 }
403
404 // Enqueue a VM_Operation to do the job for us - sometime later
405 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
406 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
407 VMThread::execute(vm_stop);
408 }
409
410
411 //
412 // Check if an external suspend request has completed (or has been
413 // cancelled). Returns true if the thread is externally suspended and
414 // false otherwise.
415 //
416 // The bits parameter returns information about the code path through
417 // the routine. Useful for debugging:
418 //
419 // set in is_ext_suspend_completed():
420 // 0x00000001 - routine was entered
421 // 0x00000010 - routine return false at end
422 // 0x00000100 - thread exited (return false)
423 // 0x00000200 - suspend request cancelled (return false)
424 // 0x00000400 - thread suspended (return true)
425 // 0x00001000 - thread is in a suspend equivalent state (return true)
426 // 0x00002000 - thread is native and walkable (return true)
427 // 0x00004000 - thread is native_trans and walkable (needed retry)
428 //
429 // set in wait_for_ext_suspend_completion():
430 // 0x00010000 - routine was entered
431 // 0x00020000 - suspend request cancelled before loop (return false)
432 // 0x00040000 - thread suspended before loop (return true)
433 // 0x00080000 - suspend request cancelled in loop (return false)
434 // 0x00100000 - thread suspended in loop (return true)
435 // 0x00200000 - suspend not completed during retry loop (return false)
436 //
437
438 // Helper class for tracing suspend wait debug bits.
439 //
440 // 0x00000100 indicates that the target thread exited before it could
441 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
442 // 0x00080000 each indicate a cancelled suspend request so they don't
443 // count as wait failures either.
444 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
445
446 class TraceSuspendDebugBits : public StackObj {
447 private:
448 JavaThread * jt;
449 bool is_wait;
450 bool called_by_wait; // meaningful when !is_wait
451 uint32_t * bits;
452
453 public:
454 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
455 uint32_t *_bits) {
456 jt = _jt;
457 is_wait = _is_wait;
458 called_by_wait = _called_by_wait;
459 bits = _bits;
460 }
461
462 ~TraceSuspendDebugBits() {
463 if (!is_wait) {
464 #if 1
465 // By default, don't trace bits for is_ext_suspend_completed() calls.
466 // That trace is very chatty.
467 return;
468 #else
469 if (!called_by_wait) {
470 // If tracing for is_ext_suspend_completed() is enabled, then only
471 // trace calls to it from wait_for_ext_suspend_completion()
472 return;
473 }
474 #endif
475 }
476
477 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
478 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
479 MutexLocker ml(Threads_lock); // needed for get_thread_name()
480 ResourceMark rm;
481
482 tty->print_cr(
483 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
484 jt->get_thread_name(), *bits);
485
486 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
487 }
488 }
489 }
490 };
491 #undef DEBUG_FALSE_BITS
492
493
494 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
495 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
496
497 bool did_trans_retry = false; // only do thread_in_native_trans retry once
498 bool do_trans_retry; // flag to force the retry
499
500 *bits |= 0x00000001;
501
502 do {
503 do_trans_retry = false;
504
505 if (is_exiting()) {
506 // Thread is in the process of exiting. This is always checked
507 // first to reduce the risk of dereferencing a freed JavaThread.
508 *bits |= 0x00000100;
509 return false;
510 }
511
512 if (!is_external_suspend()) {
513 // Suspend request is cancelled. This is always checked before
514 // is_ext_suspended() to reduce the risk of a rogue resume
515 // confusing the thread that made the suspend request.
516 *bits |= 0x00000200;
517 return false;
518 }
519
520 if (is_ext_suspended()) {
521 // thread is suspended
522 *bits |= 0x00000400;
523 return true;
524 }
525
526 // Now that we no longer do hard suspends of threads running
527 // native code, the target thread can be changing thread state
528 // while we are in this routine:
529 //
530 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
531 //
532 // We save a copy of the thread state as observed at this moment
533 // and make our decision about suspend completeness based on the
534 // copy. This closes the race where the thread state is seen as
535 // _thread_in_native_trans in the if-thread_blocked check, but is
536 // seen as _thread_blocked in if-thread_in_native_trans check.
537 JavaThreadState save_state = thread_state();
538
539 if (save_state == _thread_blocked && is_suspend_equivalent()) {
540 // If the thread's state is _thread_blocked and this blocking
541 // condition is known to be equivalent to a suspend, then we can
542 // consider the thread to be externally suspended. This means that
543 // the code that sets _thread_blocked has been modified to do
544 // self-suspension if the blocking condition releases. We also
545 // used to check for CONDVAR_WAIT here, but that is now covered by
546 // the _thread_blocked with self-suspension check.
547 //
548 // Return true since we wouldn't be here unless there was still an
549 // external suspend request.
550 *bits |= 0x00001000;
551 return true;
552 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
553 // Threads running native code will self-suspend on native==>VM/Java
554 // transitions. If its stack is walkable (should always be the case
555 // unless this function is called before the actual java_suspend()
556 // call), then the wait is done.
557 *bits |= 0x00002000;
558 return true;
559 } else if (!called_by_wait && !did_trans_retry &&
560 save_state == _thread_in_native_trans &&
561 frame_anchor()->walkable()) {
562 // The thread is transitioning from thread_in_native to another
563 // thread state. check_safepoint_and_suspend_for_native_trans()
564 // will force the thread to self-suspend. If it hasn't gotten
565 // there yet we may have caught the thread in-between the native
566 // code check above and the self-suspend. Lucky us. If we were
567 // called by wait_for_ext_suspend_completion(), then it
568 // will be doing the retries so we don't have to.
569 //
570 // Since we use the saved thread state in the if-statement above,
571 // there is a chance that the thread has already transitioned to
572 // _thread_blocked by the time we get here. In that case, we will
573 // make a single unnecessary pass through the logic below. This
574 // doesn't hurt anything since we still do the trans retry.
575
576 *bits |= 0x00004000;
577
578 // Once the thread leaves thread_in_native_trans for another
579 // thread state, we break out of this retry loop. We shouldn't
580 // need this flag to prevent us from getting back here, but
581 // sometimes paranoia is good.
582 did_trans_retry = true;
583
584 // We wait for the thread to transition to a more usable state.
585 for (int i = 1; i <= SuspendRetryCount; i++) {
586 // We used to do an "os::yield_all(i)" call here with the intention
587 // that yielding would increase on each retry. However, the parameter
588 // is ignored on Linux which means the yield didn't scale up. Waiting
589 // on the SR_lock below provides a much more predictable scale up for
590 // the delay. It also provides a simple/direct point to check for any
591 // safepoint requests from the VMThread
592
593 // temporarily drops SR_lock while doing wait with safepoint check
594 // (if we're a JavaThread - the WatcherThread can also call this)
595 // and increase delay with each retry
596 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
597
598 // check the actual thread state instead of what we saved above
599 if (thread_state() != _thread_in_native_trans) {
600 // the thread has transitioned to another thread state so
601 // try all the checks (except this one) one more time.
602 do_trans_retry = true;
603 break;
604 }
605 } // end retry loop
606
607
608 }
609 } while (do_trans_retry);
610
611 *bits |= 0x00000010;
612 return false;
613 }
614
615 //
616 // Wait for an external suspend request to complete (or be cancelled).
617 // Returns true if the thread is externally suspended and false otherwise.
618 //
619 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
620 uint32_t *bits) {
621 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
622 false /* !called_by_wait */, bits);
623
624 // local flag copies to minimize SR_lock hold time
625 bool is_suspended;
626 bool pending;
627 uint32_t reset_bits;
628
629 // set a marker so is_ext_suspend_completed() knows we are the caller
630 *bits |= 0x00010000;
631
632 // We use reset_bits to reinitialize the bits value at the top of
633 // each retry loop. This allows the caller to make use of any
634 // unused bits for their own marking purposes.
635 reset_bits = *bits;
636
637 {
638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
639 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
640 delay, bits);
641 pending = is_external_suspend();
642 }
643 // must release SR_lock to allow suspension to complete
644
645 if (!pending) {
646 // A cancelled suspend request is the only false return from
647 // is_ext_suspend_completed() that keeps us from entering the
648 // retry loop.
649 *bits |= 0x00020000;
650 return false;
651 }
652
653 if (is_suspended) {
654 *bits |= 0x00040000;
655 return true;
656 }
657
658 for (int i = 1; i <= retries; i++) {
659 *bits = reset_bits; // reinit to only track last retry
660
661 // We used to do an "os::yield_all(i)" call here with the intention
662 // that yielding would increase on each retry. However, the parameter
663 // is ignored on Linux which means the yield didn't scale up. Waiting
664 // on the SR_lock below provides a much more predictable scale up for
665 // the delay. It also provides a simple/direct point to check for any
666 // safepoint requests from the VMThread
667
668 {
669 MutexLocker ml(SR_lock());
670 // wait with safepoint check (if we're a JavaThread - the WatcherThread
671 // can also call this) and increase delay with each retry
672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
673
674 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
675 delay, bits);
676
677 // It is possible for the external suspend request to be cancelled
678 // (by a resume) before the actual suspend operation is completed.
679 // Refresh our local copy to see if we still need to wait.
680 pending = is_external_suspend();
681 }
682
683 if (!pending) {
684 // A cancelled suspend request is the only false return from
685 // is_ext_suspend_completed() that keeps us from staying in the
686 // retry loop.
687 *bits |= 0x00080000;
688 return false;
689 }
690
691 if (is_suspended) {
692 *bits |= 0x00100000;
693 return true;
694 }
695 } // end retry loop
696
697 // thread did not suspend after all our retries
698 *bits |= 0x00200000;
699 return false;
700 }
701
702 #ifndef PRODUCT
703 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
704
705 // This should not need to be atomic as the only way for simultaneous
706 // updates is via interrupts. Even then this should be rare or non-existant
707 // and we don't care that much anyway.
708
709 int index = _jmp_ring_index;
710 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
711 _jmp_ring[index]._target = (intptr_t) target;
712 _jmp_ring[index]._instruction = (intptr_t) instr;
713 _jmp_ring[index]._file = file;
714 _jmp_ring[index]._line = line;
715 }
716 #endif /* PRODUCT */
717
718 // Called by flat profiler
719 // Callers have already called wait_for_ext_suspend_completion
720 // The assertion for that is currently too complex to put here:
721 bool JavaThread::profile_last_Java_frame(frame* _fr) {
722 bool gotframe = false;
723 // self suspension saves needed state.
724 if (has_last_Java_frame() && _anchor.walkable()) {
725 *_fr = pd_last_frame();
726 gotframe = true;
727 }
728 return gotframe;
729 }
730
731 void Thread::interrupt(Thread* thread) {
732 trace("interrupt", thread);
733 debug_only(check_for_dangling_thread_pointer(thread);)
734 os::interrupt(thread);
735 }
736
737 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
738 trace("is_interrupted", thread);
739 debug_only(check_for_dangling_thread_pointer(thread);)
740 // Note: If clear_interrupted==false, this simply fetches and
741 // returns the value of the field osthread()->interrupted().
742 return os::is_interrupted(thread, clear_interrupted);
743 }
744
745
746 // GC Support
747 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
748 jint thread_parity = _oops_do_parity;
749 if (thread_parity != strong_roots_parity) {
750 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
751 if (res == thread_parity) return true;
752 else {
753 guarantee(res == strong_roots_parity, "Or else what?");
754 assert(SharedHeap::heap()->n_par_threads() > 0,
755 "Should only fail when parallel.");
756 return false;
757 }
758 }
759 assert(SharedHeap::heap()->n_par_threads() > 0,
760 "Should only fail when parallel.");
761 return false;
762 }
763
764 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
765 active_handles()->oops_do(f);
766 // Do oop for ThreadShadow
767 f->do_oop((oop*)&_pending_exception);
768 handle_area()->oops_do(f);
769 }
770
771 void Thread::nmethods_do(CodeBlobClosure* cf) {
772 // no nmethods in a generic thread...
773 }
774
775 void Thread::print_on(outputStream* st) const {
776 // get_priority assumes osthread initialized
777 if (osthread() != NULL) {
778 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
779 osthread()->print_on(st);
780 }
781 debug_only(if (WizardMode) print_owned_locks_on(st);)
782 }
783
784 // Thread::print_on_error() is called by fatal error handler. Don't use
785 // any lock or allocate memory.
786 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
787 if (is_VM_thread()) st->print("VMThread");
788 else if (is_Compiler_thread()) st->print("CompilerThread");
789 else if (is_Java_thread()) st->print("JavaThread");
790 else if (is_GC_task_thread()) st->print("GCTaskThread");
791 else if (is_Watcher_thread()) st->print("WatcherThread");
792 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
793 else st->print("Thread");
794
795 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
796 _stack_base - _stack_size, _stack_base);
797
798 if (osthread()) {
799 st->print(" [id=%d]", osthread()->thread_id());
800 }
801 }
802
803 #ifdef ASSERT
804 void Thread::print_owned_locks_on(outputStream* st) const {
805 Monitor *cur = _owned_locks;
806 if (cur == NULL) {
807 st->print(" (no locks) ");
808 } else {
809 st->print_cr(" Locks owned:");
810 while(cur) {
811 cur->print_on(st);
812 cur = cur->next();
813 }
814 }
815 }
816
817 static int ref_use_count = 0;
818
819 bool Thread::owns_locks_but_compiled_lock() const {
820 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
821 if (cur != Compile_lock) return true;
822 }
823 return false;
824 }
825
826
827 #endif
828
829 #ifndef PRODUCT
830
831 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
832 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
833 // no threads which allow_vm_block's are held
834 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
835 // Check if current thread is allowed to block at a safepoint
836 if (!(_allow_safepoint_count == 0))
837 fatal("Possible safepoint reached by thread that does not allow it");
838 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
839 fatal("LEAF method calling lock?");
840 }
841
842 #ifdef ASSERT
843 if (potential_vm_operation && is_Java_thread()
844 && !Universe::is_bootstrapping()) {
845 // Make sure we do not hold any locks that the VM thread also uses.
846 // This could potentially lead to deadlocks
847 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
848 // Threads_lock is special, since the safepoint synchronization will not start before this is
849 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
850 // since it is used to transfer control between JavaThreads and the VMThread
851 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
852 if ( (cur->allow_vm_block() &&
853 cur != Threads_lock &&
854 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
855 cur != VMOperationRequest_lock &&
856 cur != VMOperationQueue_lock) ||
857 cur->rank() == Mutex::special) {
858 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
859 }
860 }
861 }
862
863 if (GCALotAtAllSafepoints) {
864 // We could enter a safepoint here and thus have a gc
865 InterfaceSupport::check_gc_alot();
866 }
867 #endif
868 }
869 #endif
870
871 bool Thread::is_in_stack(address adr) const {
872 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
873 address end = os::current_stack_pointer();
874 if (stack_base() >= adr && adr >= end) return true;
875
876 return false;
877 }
878
879
880 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
881 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
882 // used for compilation in the future. If that change is made, the need for these methods
883 // should be revisited, and they should be removed if possible.
884
885 bool Thread::is_lock_owned(address adr) const {
886 return on_local_stack(adr);
887 }
888
889 bool Thread::set_as_starting_thread() {
890 // NOTE: this must be called inside the main thread.
891 return os::create_main_thread((JavaThread*)this);
892 }
893
894 static void initialize_class(Symbol* class_name, TRAPS) {
895 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
896 instanceKlass::cast(klass)->initialize(CHECK);
897 }
898
899
900 // Creates the initial ThreadGroup
901 static Handle create_initial_thread_group(TRAPS) {
902 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
903 instanceKlassHandle klass (THREAD, k);
904
905 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
906 {
907 JavaValue result(T_VOID);
908 JavaCalls::call_special(&result,
909 system_instance,
910 klass,
911 vmSymbols::object_initializer_name(),
912 vmSymbols::void_method_signature(),
913 CHECK_NH);
914 }
915 Universe::set_system_thread_group(system_instance());
916
917 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
918 {
919 JavaValue result(T_VOID);
920 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
921 JavaCalls::call_special(&result,
922 main_instance,
923 klass,
924 vmSymbols::object_initializer_name(),
925 vmSymbols::threadgroup_string_void_signature(),
926 system_instance,
927 string,
928 CHECK_NH);
929 }
930 return main_instance;
931 }
932
933 // Creates the initial Thread
934 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
935 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
936 instanceKlassHandle klass (THREAD, k);
937 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
938
939 java_lang_Thread::set_thread(thread_oop(), thread);
940 java_lang_Thread::set_priority(thread_oop(), NormPriority);
941 thread->set_threadObj(thread_oop());
942
943 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
944
945 JavaValue result(T_VOID);
946 JavaCalls::call_special(&result, thread_oop,
947 klass,
948 vmSymbols::object_initializer_name(),
949 vmSymbols::threadgroup_string_void_signature(),
950 thread_group,
951 string,
952 CHECK_NULL);
953 return thread_oop();
954 }
955
956 static void call_initializeSystemClass(TRAPS) {
957 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
958 instanceKlassHandle klass (THREAD, k);
959
960 JavaValue result(T_VOID);
961 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
962 vmSymbols::void_method_signature(), CHECK);
963 }
964
965 // General purpose hook into Java code, run once when the VM is initialized.
966 // The Java library method itself may be changed independently from the VM.
967 static void call_postVMInitHook(TRAPS) {
968 klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass();
969 instanceKlassHandle klass (THREAD, k);
970 if (klass.not_null()) {
971 JavaValue result(T_VOID);
972 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
973 vmSymbols::void_method_signature(),
974 CHECK);
975 }
976 }
977
978 static void reset_vm_info_property(TRAPS) {
979 // the vm info string
980 ResourceMark rm(THREAD);
981 const char *vm_info = VM_Version::vm_info_string();
982
983 // java.lang.System class
984 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
985 instanceKlassHandle klass (THREAD, k);
986
987 // setProperty arguments
988 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
989 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
990
991 // return value
992 JavaValue r(T_OBJECT);
993
994 // public static String setProperty(String key, String value);
995 JavaCalls::call_static(&r,
996 klass,
997 vmSymbols::setProperty_name(),
998 vmSymbols::string_string_string_signature(),
999 key_str,
1000 value_str,
1001 CHECK);
1002 }
1003
1004
1005 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1006 assert(thread_group.not_null(), "thread group should be specified");
1007 assert(threadObj() == NULL, "should only create Java thread object once");
1008
1009 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1010 instanceKlassHandle klass (THREAD, k);
1011 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1012
1013 java_lang_Thread::set_thread(thread_oop(), this);
1014 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1015 set_threadObj(thread_oop());
1016
1017 JavaValue result(T_VOID);
1018 if (thread_name != NULL) {
1019 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1020 // Thread gets assigned specified name and null target
1021 JavaCalls::call_special(&result,
1022 thread_oop,
1023 klass,
1024 vmSymbols::object_initializer_name(),
1025 vmSymbols::threadgroup_string_void_signature(),
1026 thread_group, // Argument 1
1027 name, // Argument 2
1028 THREAD);
1029 } else {
1030 // Thread gets assigned name "Thread-nnn" and null target
1031 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1032 JavaCalls::call_special(&result,
1033 thread_oop,
1034 klass,
1035 vmSymbols::object_initializer_name(),
1036 vmSymbols::threadgroup_runnable_void_signature(),
1037 thread_group, // Argument 1
1038 Handle(), // Argument 2
1039 THREAD);
1040 }
1041
1042
1043 if (daemon) {
1044 java_lang_Thread::set_daemon(thread_oop());
1045 }
1046
1047 if (HAS_PENDING_EXCEPTION) {
1048 return;
1049 }
1050
1051 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1052 Handle threadObj(this, this->threadObj());
1053
1054 JavaCalls::call_special(&result,
1055 thread_group,
1056 group,
1057 vmSymbols::add_method_name(),
1058 vmSymbols::thread_void_signature(),
1059 threadObj, // Arg 1
1060 THREAD);
1061
1062
1063 }
1064
1065 // NamedThread -- non-JavaThread subclasses with multiple
1066 // uniquely named instances should derive from this.
1067 NamedThread::NamedThread() : Thread() {
1068 _name = NULL;
1069 _processed_thread = NULL;
1070 }
1071
1072 NamedThread::~NamedThread() {
1073 if (_name != NULL) {
1074 FREE_C_HEAP_ARRAY(char, _name);
1075 _name = NULL;
1076 }
1077 }
1078
1079 void NamedThread::set_name(const char* format, ...) {
1080 guarantee(_name == NULL, "Only get to set name once.");
1081 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1082 guarantee(_name != NULL, "alloc failure");
1083 va_list ap;
1084 va_start(ap, format);
1085 jio_vsnprintf(_name, max_name_len, format, ap);
1086 va_end(ap);
1087 }
1088
1089 // ======= WatcherThread ========
1090
1091 // The watcher thread exists to simulate timer interrupts. It should
1092 // be replaced by an abstraction over whatever native support for
1093 // timer interrupts exists on the platform.
1094
1095 WatcherThread* WatcherThread::_watcher_thread = NULL;
1096 volatile bool WatcherThread::_should_terminate = false;
1097
1098 WatcherThread::WatcherThread() : Thread() {
1099 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1100 if (os::create_thread(this, os::watcher_thread)) {
1101 _watcher_thread = this;
1102
1103 // Set the watcher thread to the highest OS priority which should not be
1104 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1105 // is created. The only normal thread using this priority is the reference
1106 // handler thread, which runs for very short intervals only.
1107 // If the VMThread's priority is not lower than the WatcherThread profiling
1108 // will be inaccurate.
1109 os::set_priority(this, MaxPriority);
1110 if (!DisableStartThread) {
1111 os::start_thread(this);
1112 }
1113 }
1114 }
1115
1116 void WatcherThread::run() {
1117 assert(this == watcher_thread(), "just checking");
1118
1119 this->record_stack_base_and_size();
1120 this->initialize_thread_local_storage();
1121 this->set_active_handles(JNIHandleBlock::allocate_block());
1122 while(!_should_terminate) {
1123 assert(watcher_thread() == Thread::current(), "thread consistency check");
1124 assert(watcher_thread() == this, "thread consistency check");
1125
1126 // Calculate how long it'll be until the next PeriodicTask work
1127 // should be done, and sleep that amount of time.
1128 size_t time_to_wait = PeriodicTask::time_to_wait();
1129
1130 // we expect this to timeout - we only ever get unparked when
1131 // we should terminate
1132 {
1133 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1134
1135 jlong prev_time = os::javaTimeNanos();
1136 for (;;) {
1137 int res= _SleepEvent->park(time_to_wait);
1138 if (res == OS_TIMEOUT || _should_terminate)
1139 break;
1140 // spurious wakeup of some kind
1141 jlong now = os::javaTimeNanos();
1142 time_to_wait -= (now - prev_time) / 1000000;
1143 if (time_to_wait <= 0)
1144 break;
1145 prev_time = now;
1146 }
1147 }
1148
1149 if (is_error_reported()) {
1150 // A fatal error has happened, the error handler(VMError::report_and_die)
1151 // should abort JVM after creating an error log file. However in some
1152 // rare cases, the error handler itself might deadlock. Here we try to
1153 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1154 //
1155 // This code is in WatcherThread because WatcherThread wakes up
1156 // periodically so the fatal error handler doesn't need to do anything;
1157 // also because the WatcherThread is less likely to crash than other
1158 // threads.
1159
1160 for (;;) {
1161 if (!ShowMessageBoxOnError
1162 && (OnError == NULL || OnError[0] == '\0')
1163 && Arguments::abort_hook() == NULL) {
1164 os::sleep(this, 2 * 60 * 1000, false);
1165 fdStream err(defaultStream::output_fd());
1166 err.print_raw_cr("# [ timer expired, abort... ]");
1167 // skip atexit/vm_exit/vm_abort hooks
1168 os::die();
1169 }
1170
1171 // Wake up 5 seconds later, the fatal handler may reset OnError or
1172 // ShowMessageBoxOnError when it is ready to abort.
1173 os::sleep(this, 5 * 1000, false);
1174 }
1175 }
1176
1177 PeriodicTask::real_time_tick(time_to_wait);
1178
1179 // If we have no more tasks left due to dynamic disenrollment,
1180 // shut down the thread since we don't currently support dynamic enrollment
1181 if (PeriodicTask::num_tasks() == 0) {
1182 _should_terminate = true;
1183 }
1184 }
1185
1186 // Signal that it is terminated
1187 {
1188 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1189 _watcher_thread = NULL;
1190 Terminator_lock->notify();
1191 }
1192
1193 // Thread destructor usually does this..
1194 ThreadLocalStorage::set_thread(NULL);
1195 }
1196
1197 void WatcherThread::start() {
1198 if (watcher_thread() == NULL) {
1199 _should_terminate = false;
1200 // Create the single instance of WatcherThread
1201 new WatcherThread();
1202 }
1203 }
1204
1205 void WatcherThread::stop() {
1206 // it is ok to take late safepoints here, if needed
1207 MutexLocker mu(Terminator_lock);
1208 _should_terminate = true;
1209 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1210
1211 Thread* watcher = watcher_thread();
1212 if (watcher != NULL)
1213 watcher->_SleepEvent->unpark();
1214
1215 while(watcher_thread() != NULL) {
1216 // This wait should make safepoint checks, wait without a timeout,
1217 // and wait as a suspend-equivalent condition.
1218 //
1219 // Note: If the FlatProfiler is running, then this thread is waiting
1220 // for the WatcherThread to terminate and the WatcherThread, via the
1221 // FlatProfiler task, is waiting for the external suspend request on
1222 // this thread to complete. wait_for_ext_suspend_completion() will
1223 // eventually timeout, but that takes time. Making this wait a
1224 // suspend-equivalent condition solves that timeout problem.
1225 //
1226 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1227 Mutex::_as_suspend_equivalent_flag);
1228 }
1229 }
1230
1231 void WatcherThread::print_on(outputStream* st) const {
1232 st->print("\"%s\" ", name());
1233 Thread::print_on(st);
1234 st->cr();
1235 }
1236
1237 // ======= JavaThread ========
1238
1239 // A JavaThread is a normal Java thread
1240
1241 void JavaThread::initialize() {
1242 // Initialize fields
1243
1244 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1245 set_claimed_par_id(-1);
1246
1247 set_saved_exception_pc(NULL);
1248 set_threadObj(NULL);
1249 _anchor.clear();
1250 set_entry_point(NULL);
1251 set_jni_functions(jni_functions());
1252 set_callee_target(NULL);
1253 set_vm_result(NULL);
1254 set_vm_result_2(NULL);
1255 set_vframe_array_head(NULL);
1256 set_vframe_array_last(NULL);
1257 set_deferred_locals(NULL);
1258 set_deopt_mark(NULL);
1259 set_deopt_nmethod(NULL);
1260 clear_must_deopt_id();
1261 set_monitor_chunks(NULL);
1262 set_next(NULL);
1263 set_thread_state(_thread_new);
1264 _terminated = _not_terminated;
1265 _privileged_stack_top = NULL;
1266 _array_for_gc = NULL;
1267 _suspend_equivalent = false;
1268 _in_deopt_handler = 0;
1269 _doing_unsafe_access = false;
1270 _stack_guard_state = stack_guard_unused;
1271 _exception_oop = NULL;
1272 _exception_pc = 0;
1273 _exception_handler_pc = 0;
1274 _exception_stack_size = 0;
1275 _is_method_handle_return = 0;
1276 _jvmti_thread_state= NULL;
1277 _should_post_on_exceptions_flag = JNI_FALSE;
1278 _jvmti_get_loaded_classes_closure = NULL;
1279 _interp_only_mode = 0;
1280 _special_runtime_exit_condition = _no_async_condition;
1281 _pending_async_exception = NULL;
1282 _is_compiling = false;
1283 _thread_stat = NULL;
1284 _thread_stat = new ThreadStatistics();
1285 _blocked_on_compilation = false;
1286 _jni_active_critical = 0;
1287 _do_not_unlock_if_synchronized = false;
1288 _cached_monitor_info = NULL;
1289 _parker = Parker::Allocate(this) ;
1290
1291 #ifndef PRODUCT
1292 _jmp_ring_index = 0;
1293 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1294 record_jump(NULL, NULL, NULL, 0);
1295 }
1296 #endif /* PRODUCT */
1297
1298 set_thread_profiler(NULL);
1299 if (FlatProfiler::is_active()) {
1300 // This is where we would decide to either give each thread it's own profiler
1301 // or use one global one from FlatProfiler,
1302 // or up to some count of the number of profiled threads, etc.
1303 ThreadProfiler* pp = new ThreadProfiler();
1304 pp->engage();
1305 set_thread_profiler(pp);
1306 }
1307
1308 // Setup safepoint state info for this thread
1309 ThreadSafepointState::create(this);
1310
1311 debug_only(_java_call_counter = 0);
1312
1313 // JVMTI PopFrame support
1314 _popframe_condition = popframe_inactive;
1315 _popframe_preserved_args = NULL;
1316 _popframe_preserved_args_size = 0;
1317
1318 pd_initialize();
1319 }
1320
1321 #ifndef SERIALGC
1322 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1323 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1324 #endif // !SERIALGC
1325
1326 JavaThread::JavaThread(bool is_attaching) :
1327 Thread()
1328 #ifndef SERIALGC
1329 , _satb_mark_queue(&_satb_mark_queue_set),
1330 _dirty_card_queue(&_dirty_card_queue_set)
1331 #endif // !SERIALGC
1332 {
1333 initialize();
1334 _is_attaching = is_attaching;
1335 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1336 }
1337
1338 bool JavaThread::reguard_stack(address cur_sp) {
1339 if (_stack_guard_state != stack_guard_yellow_disabled) {
1340 return true; // Stack already guarded or guard pages not needed.
1341 }
1342
1343 if (register_stack_overflow()) {
1344 // For those architectures which have separate register and
1345 // memory stacks, we must check the register stack to see if
1346 // it has overflowed.
1347 return false;
1348 }
1349
1350 // Java code never executes within the yellow zone: the latter is only
1351 // there to provoke an exception during stack banging. If java code
1352 // is executing there, either StackShadowPages should be larger, or
1353 // some exception code in c1, c2 or the interpreter isn't unwinding
1354 // when it should.
1355 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1356
1357 enable_stack_yellow_zone();
1358 return true;
1359 }
1360
1361 bool JavaThread::reguard_stack(void) {
1362 return reguard_stack(os::current_stack_pointer());
1363 }
1364
1365
1366 void JavaThread::block_if_vm_exited() {
1367 if (_terminated == _vm_exited) {
1368 // _vm_exited is set at safepoint, and Threads_lock is never released
1369 // we will block here forever
1370 Threads_lock->lock_without_safepoint_check();
1371 ShouldNotReachHere();
1372 }
1373 }
1374
1375
1376 // Remove this ifdef when C1 is ported to the compiler interface.
1377 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1378
1379 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1380 Thread()
1381 #ifndef SERIALGC
1382 , _satb_mark_queue(&_satb_mark_queue_set),
1383 _dirty_card_queue(&_dirty_card_queue_set)
1384 #endif // !SERIALGC
1385 {
1386 if (TraceThreadEvents) {
1387 tty->print_cr("creating thread %p", this);
1388 }
1389 initialize();
1390 _is_attaching = false;
1391 set_entry_point(entry_point);
1392 // Create the native thread itself.
1393 // %note runtime_23
1394 os::ThreadType thr_type = os::java_thread;
1395 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1396 os::java_thread;
1397 os::create_thread(this, thr_type, stack_sz);
1398
1399 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1400 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1401 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1402 // the exception consists of creating the exception object & initializing it, initialization
1403 // will leave the VM via a JavaCall and then all locks must be unlocked).
1404 //
1405 // The thread is still suspended when we reach here. Thread must be explicit started
1406 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1407 // by calling Threads:add. The reason why this is not done here, is because the thread
1408 // object must be fully initialized (take a look at JVM_Start)
1409 }
1410
1411 JavaThread::~JavaThread() {
1412 if (TraceThreadEvents) {
1413 tty->print_cr("terminate thread %p", this);
1414 }
1415
1416 // JSR166 -- return the parker to the free list
1417 Parker::Release(_parker);
1418 _parker = NULL ;
1419
1420 // Free any remaining previous UnrollBlock
1421 vframeArray* old_array = vframe_array_last();
1422
1423 if (old_array != NULL) {
1424 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1425 old_array->set_unroll_block(NULL);
1426 delete old_info;
1427 delete old_array;
1428 }
1429
1430 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1431 if (deferred != NULL) {
1432 // This can only happen if thread is destroyed before deoptimization occurs.
1433 assert(deferred->length() != 0, "empty array!");
1434 do {
1435 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1436 deferred->remove_at(0);
1437 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1438 delete dlv;
1439 } while (deferred->length() != 0);
1440 delete deferred;
1441 }
1442
1443 // All Java related clean up happens in exit
1444 ThreadSafepointState::destroy(this);
1445 if (_thread_profiler != NULL) delete _thread_profiler;
1446 if (_thread_stat != NULL) delete _thread_stat;
1447 }
1448
1449
1450 // The first routine called by a new Java thread
1451 void JavaThread::run() {
1452 // initialize thread-local alloc buffer related fields
1453 this->initialize_tlab();
1454
1455 // used to test validitity of stack trace backs
1456 this->record_base_of_stack_pointer();
1457
1458 // Record real stack base and size.
1459 this->record_stack_base_and_size();
1460
1461 // Initialize thread local storage; set before calling MutexLocker
1462 this->initialize_thread_local_storage();
1463
1464 this->create_stack_guard_pages();
1465
1466 this->cache_global_variables();
1467
1468 // Thread is now sufficient initialized to be handled by the safepoint code as being
1469 // in the VM. Change thread state from _thread_new to _thread_in_vm
1470 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1471
1472 assert(JavaThread::current() == this, "sanity check");
1473 assert(!Thread::current()->owns_locks(), "sanity check");
1474
1475 DTRACE_THREAD_PROBE(start, this);
1476
1477 // This operation might block. We call that after all safepoint checks for a new thread has
1478 // been completed.
1479 this->set_active_handles(JNIHandleBlock::allocate_block());
1480
1481 if (JvmtiExport::should_post_thread_life()) {
1482 JvmtiExport::post_thread_start(this);
1483 }
1484
1485 // We call another function to do the rest so we are sure that the stack addresses used
1486 // from there will be lower than the stack base just computed
1487 thread_main_inner();
1488
1489 // Note, thread is no longer valid at this point!
1490 }
1491
1492
1493 void JavaThread::thread_main_inner() {
1494 assert(JavaThread::current() == this, "sanity check");
1495 assert(this->threadObj() != NULL, "just checking");
1496
1497 // Execute thread entry point unless this thread has a pending exception
1498 // or has been stopped before starting.
1499 // Note: Due to JVM_StopThread we can have pending exceptions already!
1500 if (!this->has_pending_exception() &&
1501 !java_lang_Thread::is_stillborn(this->threadObj())) {
1502 HandleMark hm(this);
1503 this->entry_point()(this, this);
1504 }
1505
1506 DTRACE_THREAD_PROBE(stop, this);
1507
1508 this->exit(false);
1509 delete this;
1510 }
1511
1512
1513 static void ensure_join(JavaThread* thread) {
1514 // We do not need to grap the Threads_lock, since we are operating on ourself.
1515 Handle threadObj(thread, thread->threadObj());
1516 assert(threadObj.not_null(), "java thread object must exist");
1517 ObjectLocker lock(threadObj, thread);
1518 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1519 thread->clear_pending_exception();
1520 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1521 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1522 // Clear the native thread instance - this makes isAlive return false and allows the join()
1523 // to complete once we've done the notify_all below
1524 java_lang_Thread::set_thread(threadObj(), NULL);
1525 lock.notify_all(thread);
1526 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1527 thread->clear_pending_exception();
1528 }
1529
1530
1531 // For any new cleanup additions, please check to see if they need to be applied to
1532 // cleanup_failed_attach_current_thread as well.
1533 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1534 assert(this == JavaThread::current(), "thread consistency check");
1535 if (!InitializeJavaLangSystem) return;
1536
1537 HandleMark hm(this);
1538 Handle uncaught_exception(this, this->pending_exception());
1539 this->clear_pending_exception();
1540 Handle threadObj(this, this->threadObj());
1541 assert(threadObj.not_null(), "Java thread object should be created");
1542
1543 if (get_thread_profiler() != NULL) {
1544 get_thread_profiler()->disengage();
1545 ResourceMark rm;
1546 get_thread_profiler()->print(get_thread_name());
1547 }
1548
1549
1550 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1551 {
1552 EXCEPTION_MARK;
1553
1554 CLEAR_PENDING_EXCEPTION;
1555 }
1556 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1557 // has to be fixed by a runtime query method
1558 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1559 // JSR-166: change call from from ThreadGroup.uncaughtException to
1560 // java.lang.Thread.dispatchUncaughtException
1561 if (uncaught_exception.not_null()) {
1562 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1563 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1564 (address)uncaught_exception(), (address)threadObj(), (address)group());
1565 {
1566 EXCEPTION_MARK;
1567 // Check if the method Thread.dispatchUncaughtException() exists. If so
1568 // call it. Otherwise we have an older library without the JSR-166 changes,
1569 // so call ThreadGroup.uncaughtException()
1570 KlassHandle recvrKlass(THREAD, threadObj->klass());
1571 CallInfo callinfo;
1572 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1573 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1574 vmSymbols::dispatchUncaughtException_name(),
1575 vmSymbols::throwable_void_signature(),
1576 KlassHandle(), false, false, THREAD);
1577 CLEAR_PENDING_EXCEPTION;
1578 methodHandle method = callinfo.selected_method();
1579 if (method.not_null()) {
1580 JavaValue result(T_VOID);
1581 JavaCalls::call_virtual(&result,
1582 threadObj, thread_klass,
1583 vmSymbols::dispatchUncaughtException_name(),
1584 vmSymbols::throwable_void_signature(),
1585 uncaught_exception,
1586 THREAD);
1587 } else {
1588 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1589 JavaValue result(T_VOID);
1590 JavaCalls::call_virtual(&result,
1591 group, thread_group,
1592 vmSymbols::uncaughtException_name(),
1593 vmSymbols::thread_throwable_void_signature(),
1594 threadObj, // Arg 1
1595 uncaught_exception, // Arg 2
1596 THREAD);
1597 }
1598 if (HAS_PENDING_EXCEPTION) {
1599 ResourceMark rm(this);
1600 jio_fprintf(defaultStream::error_stream(),
1601 "\nException: %s thrown from the UncaughtExceptionHandler"
1602 " in thread \"%s\"\n",
1603 Klass::cast(pending_exception()->klass())->external_name(),
1604 get_thread_name());
1605 CLEAR_PENDING_EXCEPTION;
1606 }
1607 }
1608 }
1609
1610 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1611 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1612 // is deprecated anyhow.
1613 { int count = 3;
1614 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1615 EXCEPTION_MARK;
1616 JavaValue result(T_VOID);
1617 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1618 JavaCalls::call_virtual(&result,
1619 threadObj, thread_klass,
1620 vmSymbols::exit_method_name(),
1621 vmSymbols::void_method_signature(),
1622 THREAD);
1623 CLEAR_PENDING_EXCEPTION;
1624 }
1625 }
1626
1627 // notify JVMTI
1628 if (JvmtiExport::should_post_thread_life()) {
1629 JvmtiExport::post_thread_end(this);
1630 }
1631
1632 // We have notified the agents that we are exiting, before we go on,
1633 // we must check for a pending external suspend request and honor it
1634 // in order to not surprise the thread that made the suspend request.
1635 while (true) {
1636 {
1637 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1638 if (!is_external_suspend()) {
1639 set_terminated(_thread_exiting);
1640 ThreadService::current_thread_exiting(this);
1641 break;
1642 }
1643 // Implied else:
1644 // Things get a little tricky here. We have a pending external
1645 // suspend request, but we are holding the SR_lock so we
1646 // can't just self-suspend. So we temporarily drop the lock
1647 // and then self-suspend.
1648 }
1649
1650 ThreadBlockInVM tbivm(this);
1651 java_suspend_self();
1652
1653 // We're done with this suspend request, but we have to loop around
1654 // and check again. Eventually we will get SR_lock without a pending
1655 // external suspend request and will be able to mark ourselves as
1656 // exiting.
1657 }
1658 // no more external suspends are allowed at this point
1659 } else {
1660 // before_exit() has already posted JVMTI THREAD_END events
1661 }
1662
1663 // Notify waiters on thread object. This has to be done after exit() is called
1664 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1665 // group should have the destroyed bit set before waiters are notified).
1666 ensure_join(this);
1667 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1668
1669 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1670 // held by this thread must be released. A detach operation must only
1671 // get here if there are no Java frames on the stack. Therefore, any
1672 // owned monitors at this point MUST be JNI-acquired monitors which are
1673 // pre-inflated and in the monitor cache.
1674 //
1675 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1676 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1677 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1678 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1679 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1680 }
1681
1682 // These things needs to be done while we are still a Java Thread. Make sure that thread
1683 // is in a consistent state, in case GC happens
1684 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1685
1686 if (active_handles() != NULL) {
1687 JNIHandleBlock* block = active_handles();
1688 set_active_handles(NULL);
1689 JNIHandleBlock::release_block(block);
1690 }
1691
1692 if (free_handle_block() != NULL) {
1693 JNIHandleBlock* block = free_handle_block();
1694 set_free_handle_block(NULL);
1695 JNIHandleBlock::release_block(block);
1696 }
1697
1698 // These have to be removed while this is still a valid thread.
1699 remove_stack_guard_pages();
1700
1701 if (UseTLAB) {
1702 tlab().make_parsable(true); // retire TLAB
1703 }
1704
1705 if (JvmtiEnv::environments_might_exist()) {
1706 JvmtiExport::cleanup_thread(this);
1707 }
1708
1709 #ifndef SERIALGC
1710 // We must flush G1-related buffers before removing a thread from
1711 // the list of active threads.
1712 if (UseG1GC) {
1713 flush_barrier_queues();
1714 }
1715 #endif
1716
1717 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1718 Threads::remove(this);
1719 }
1720
1721 #ifndef SERIALGC
1722 // Flush G1-related queues.
1723 void JavaThread::flush_barrier_queues() {
1724 satb_mark_queue().flush();
1725 dirty_card_queue().flush();
1726 }
1727
1728 void JavaThread::initialize_queues() {
1729 assert(!SafepointSynchronize::is_at_safepoint(),
1730 "we should not be at a safepoint");
1731
1732 ObjPtrQueue& satb_queue = satb_mark_queue();
1733 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1734 // The SATB queue should have been constructed with its active
1735 // field set to false.
1736 assert(!satb_queue.is_active(), "SATB queue should not be active");
1737 assert(satb_queue.is_empty(), "SATB queue should be empty");
1738 // If we are creating the thread during a marking cycle, we should
1739 // set the active field of the SATB queue to true.
1740 if (satb_queue_set.is_active()) {
1741 satb_queue.set_active(true);
1742 }
1743
1744 DirtyCardQueue& dirty_queue = dirty_card_queue();
1745 // The dirty card queue should have been constructed with its
1746 // active field set to true.
1747 assert(dirty_queue.is_active(), "dirty card queue should be active");
1748 }
1749 #endif // !SERIALGC
1750
1751 void JavaThread::cleanup_failed_attach_current_thread() {
1752 if (get_thread_profiler() != NULL) {
1753 get_thread_profiler()->disengage();
1754 ResourceMark rm;
1755 get_thread_profiler()->print(get_thread_name());
1756 }
1757
1758 if (active_handles() != NULL) {
1759 JNIHandleBlock* block = active_handles();
1760 set_active_handles(NULL);
1761 JNIHandleBlock::release_block(block);
1762 }
1763
1764 if (free_handle_block() != NULL) {
1765 JNIHandleBlock* block = free_handle_block();
1766 set_free_handle_block(NULL);
1767 JNIHandleBlock::release_block(block);
1768 }
1769
1770 // These have to be removed while this is still a valid thread.
1771 remove_stack_guard_pages();
1772
1773 if (UseTLAB) {
1774 tlab().make_parsable(true); // retire TLAB, if any
1775 }
1776
1777 #ifndef SERIALGC
1778 if (UseG1GC) {
1779 flush_barrier_queues();
1780 }
1781 #endif
1782
1783 Threads::remove(this);
1784 delete this;
1785 }
1786
1787
1788
1789
1790 JavaThread* JavaThread::active() {
1791 Thread* thread = ThreadLocalStorage::thread();
1792 assert(thread != NULL, "just checking");
1793 if (thread->is_Java_thread()) {
1794 return (JavaThread*) thread;
1795 } else {
1796 assert(thread->is_VM_thread(), "this must be a vm thread");
1797 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1798 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1799 assert(ret->is_Java_thread(), "must be a Java thread");
1800 return ret;
1801 }
1802 }
1803
1804 bool JavaThread::is_lock_owned(address adr) const {
1805 if (Thread::is_lock_owned(adr)) return true;
1806
1807 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1808 if (chunk->contains(adr)) return true;
1809 }
1810
1811 return false;
1812 }
1813
1814
1815 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1816 chunk->set_next(monitor_chunks());
1817 set_monitor_chunks(chunk);
1818 }
1819
1820 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1821 guarantee(monitor_chunks() != NULL, "must be non empty");
1822 if (monitor_chunks() == chunk) {
1823 set_monitor_chunks(chunk->next());
1824 } else {
1825 MonitorChunk* prev = monitor_chunks();
1826 while (prev->next() != chunk) prev = prev->next();
1827 prev->set_next(chunk->next());
1828 }
1829 }
1830
1831 // JVM support.
1832
1833 // Note: this function shouldn't block if it's called in
1834 // _thread_in_native_trans state (such as from
1835 // check_special_condition_for_native_trans()).
1836 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1837
1838 if (has_last_Java_frame() && has_async_condition()) {
1839 // If we are at a polling page safepoint (not a poll return)
1840 // then we must defer async exception because live registers
1841 // will be clobbered by the exception path. Poll return is
1842 // ok because the call we a returning from already collides
1843 // with exception handling registers and so there is no issue.
1844 // (The exception handling path kills call result registers but
1845 // this is ok since the exception kills the result anyway).
1846
1847 if (is_at_poll_safepoint()) {
1848 // if the code we are returning to has deoptimized we must defer
1849 // the exception otherwise live registers get clobbered on the
1850 // exception path before deoptimization is able to retrieve them.
1851 //
1852 RegisterMap map(this, false);
1853 frame caller_fr = last_frame().sender(&map);
1854 assert(caller_fr.is_compiled_frame(), "what?");
1855 if (caller_fr.is_deoptimized_frame()) {
1856 if (TraceExceptions) {
1857 ResourceMark rm;
1858 tty->print_cr("deferred async exception at compiled safepoint");
1859 }
1860 return;
1861 }
1862 }
1863 }
1864
1865 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1866 if (condition == _no_async_condition) {
1867 // Conditions have changed since has_special_runtime_exit_condition()
1868 // was called:
1869 // - if we were here only because of an external suspend request,
1870 // then that was taken care of above (or cancelled) so we are done
1871 // - if we were here because of another async request, then it has
1872 // been cleared between the has_special_runtime_exit_condition()
1873 // and now so again we are done
1874 return;
1875 }
1876
1877 // Check for pending async. exception
1878 if (_pending_async_exception != NULL) {
1879 // Only overwrite an already pending exception, if it is not a threadDeath.
1880 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1881
1882 // We cannot call Exceptions::_throw(...) here because we cannot block
1883 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1884
1885 if (TraceExceptions) {
1886 ResourceMark rm;
1887 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1888 if (has_last_Java_frame() ) {
1889 frame f = last_frame();
1890 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1891 }
1892 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1893 }
1894 _pending_async_exception = NULL;
1895 clear_has_async_exception();
1896 }
1897 }
1898
1899 if (check_unsafe_error &&
1900 condition == _async_unsafe_access_error && !has_pending_exception()) {
1901 condition = _no_async_condition; // done
1902 switch (thread_state()) {
1903 case _thread_in_vm:
1904 {
1905 JavaThread* THREAD = this;
1906 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1907 }
1908 case _thread_in_native:
1909 {
1910 ThreadInVMfromNative tiv(this);
1911 JavaThread* THREAD = this;
1912 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1913 }
1914 case _thread_in_Java:
1915 {
1916 ThreadInVMfromJava tiv(this);
1917 JavaThread* THREAD = this;
1918 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1919 }
1920 default:
1921 ShouldNotReachHere();
1922 }
1923 }
1924
1925 assert(condition == _no_async_condition || has_pending_exception() ||
1926 (!check_unsafe_error && condition == _async_unsafe_access_error),
1927 "must have handled the async condition, if no exception");
1928 }
1929
1930 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1931 //
1932 // Check for pending external suspend. Internal suspend requests do
1933 // not use handle_special_runtime_exit_condition().
1934 // If JNIEnv proxies are allowed, don't self-suspend if the target
1935 // thread is not the current thread. In older versions of jdbx, jdbx
1936 // threads could call into the VM with another thread's JNIEnv so we
1937 // can be here operating on behalf of a suspended thread (4432884).
1938 bool do_self_suspend = is_external_suspend_with_lock();
1939 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1940 //
1941 // Because thread is external suspended the safepoint code will count
1942 // thread as at a safepoint. This can be odd because we can be here
1943 // as _thread_in_Java which would normally transition to _thread_blocked
1944 // at a safepoint. We would like to mark the thread as _thread_blocked
1945 // before calling java_suspend_self like all other callers of it but
1946 // we must then observe proper safepoint protocol. (We can't leave
1947 // _thread_blocked with a safepoint in progress). However we can be
1948 // here as _thread_in_native_trans so we can't use a normal transition
1949 // constructor/destructor pair because they assert on that type of
1950 // transition. We could do something like:
1951 //
1952 // JavaThreadState state = thread_state();
1953 // set_thread_state(_thread_in_vm);
1954 // {
1955 // ThreadBlockInVM tbivm(this);
1956 // java_suspend_self()
1957 // }
1958 // set_thread_state(_thread_in_vm_trans);
1959 // if (safepoint) block;
1960 // set_thread_state(state);
1961 //
1962 // but that is pretty messy. Instead we just go with the way the
1963 // code has worked before and note that this is the only path to
1964 // java_suspend_self that doesn't put the thread in _thread_blocked
1965 // mode.
1966
1967 frame_anchor()->make_walkable(this);
1968 java_suspend_self();
1969
1970 // We might be here for reasons in addition to the self-suspend request
1971 // so check for other async requests.
1972 }
1973
1974 if (check_asyncs) {
1975 check_and_handle_async_exceptions();
1976 }
1977 }
1978
1979 void JavaThread::send_thread_stop(oop java_throwable) {
1980 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1981 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1982 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1983
1984 // Do not throw asynchronous exceptions against the compiler thread
1985 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1986 if (is_Compiler_thread()) return;
1987
1988 {
1989 // Actually throw the Throwable against the target Thread - however
1990 // only if there is no thread death exception installed already.
1991 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1992 // If the topmost frame is a runtime stub, then we are calling into
1993 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1994 // must deoptimize the caller before continuing, as the compiled exception handler table
1995 // may not be valid
1996 if (has_last_Java_frame()) {
1997 frame f = last_frame();
1998 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
1999 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2000 RegisterMap reg_map(this, UseBiasedLocking);
2001 frame compiled_frame = f.sender(®_map);
2002 if (compiled_frame.can_be_deoptimized()) {
2003 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2004 }
2005 }
2006 }
2007
2008 // Set async. pending exception in thread.
2009 set_pending_async_exception(java_throwable);
2010
2011 if (TraceExceptions) {
2012 ResourceMark rm;
2013 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2014 }
2015 // for AbortVMOnException flag
2016 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2017 }
2018 }
2019
2020
2021 // Interrupt thread so it will wake up from a potential wait()
2022 Thread::interrupt(this);
2023 }
2024
2025 // External suspension mechanism.
2026 //
2027 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2028 // to any VM_locks and it is at a transition
2029 // Self-suspension will happen on the transition out of the vm.
2030 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2031 //
2032 // Guarantees on return:
2033 // + Target thread will not execute any new bytecode (that's why we need to
2034 // force a safepoint)
2035 // + Target thread will not enter any new monitors
2036 //
2037 void JavaThread::java_suspend() {
2038 { MutexLocker mu(Threads_lock);
2039 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2040 return;
2041 }
2042 }
2043
2044 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2045 if (!is_external_suspend()) {
2046 // a racing resume has cancelled us; bail out now
2047 return;
2048 }
2049
2050 // suspend is done
2051 uint32_t debug_bits = 0;
2052 // Warning: is_ext_suspend_completed() may temporarily drop the
2053 // SR_lock to allow the thread to reach a stable thread state if
2054 // it is currently in a transient thread state.
2055 if (is_ext_suspend_completed(false /* !called_by_wait */,
2056 SuspendRetryDelay, &debug_bits) ) {
2057 return;
2058 }
2059 }
2060
2061 VM_ForceSafepoint vm_suspend;
2062 VMThread::execute(&vm_suspend);
2063 }
2064
2065 // Part II of external suspension.
2066 // A JavaThread self suspends when it detects a pending external suspend
2067 // request. This is usually on transitions. It is also done in places
2068 // where continuing to the next transition would surprise the caller,
2069 // e.g., monitor entry.
2070 //
2071 // Returns the number of times that the thread self-suspended.
2072 //
2073 // Note: DO NOT call java_suspend_self() when you just want to block current
2074 // thread. java_suspend_self() is the second stage of cooperative
2075 // suspension for external suspend requests and should only be used
2076 // to complete an external suspend request.
2077 //
2078 int JavaThread::java_suspend_self() {
2079 int ret = 0;
2080
2081 // we are in the process of exiting so don't suspend
2082 if (is_exiting()) {
2083 clear_external_suspend();
2084 return ret;
2085 }
2086
2087 assert(_anchor.walkable() ||
2088 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2089 "must have walkable stack");
2090
2091 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2092
2093 assert(!this->is_ext_suspended(),
2094 "a thread trying to self-suspend should not already be suspended");
2095
2096 if (this->is_suspend_equivalent()) {
2097 // If we are self-suspending as a result of the lifting of a
2098 // suspend equivalent condition, then the suspend_equivalent
2099 // flag is not cleared until we set the ext_suspended flag so
2100 // that wait_for_ext_suspend_completion() returns consistent
2101 // results.
2102 this->clear_suspend_equivalent();
2103 }
2104
2105 // A racing resume may have cancelled us before we grabbed SR_lock
2106 // above. Or another external suspend request could be waiting for us
2107 // by the time we return from SR_lock()->wait(). The thread
2108 // that requested the suspension may already be trying to walk our
2109 // stack and if we return now, we can change the stack out from under
2110 // it. This would be a "bad thing (TM)" and cause the stack walker
2111 // to crash. We stay self-suspended until there are no more pending
2112 // external suspend requests.
2113 while (is_external_suspend()) {
2114 ret++;
2115 this->set_ext_suspended();
2116
2117 // _ext_suspended flag is cleared by java_resume()
2118 while (is_ext_suspended()) {
2119 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2120 }
2121 }
2122
2123 return ret;
2124 }
2125
2126 #ifdef ASSERT
2127 // verify the JavaThread has not yet been published in the Threads::list, and
2128 // hence doesn't need protection from concurrent access at this stage
2129 void JavaThread::verify_not_published() {
2130 if (!Threads_lock->owned_by_self()) {
2131 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2132 assert( !Threads::includes(this),
2133 "java thread shouldn't have been published yet!");
2134 }
2135 else {
2136 assert( !Threads::includes(this),
2137 "java thread shouldn't have been published yet!");
2138 }
2139 }
2140 #endif
2141
2142 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2143 // progress or when _suspend_flags is non-zero.
2144 // Current thread needs to self-suspend if there is a suspend request and/or
2145 // block if a safepoint is in progress.
2146 // Async exception ISN'T checked.
2147 // Note only the ThreadInVMfromNative transition can call this function
2148 // directly and when thread state is _thread_in_native_trans
2149 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2150 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2151
2152 JavaThread *curJT = JavaThread::current();
2153 bool do_self_suspend = thread->is_external_suspend();
2154
2155 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2156
2157 // If JNIEnv proxies are allowed, don't self-suspend if the target
2158 // thread is not the current thread. In older versions of jdbx, jdbx
2159 // threads could call into the VM with another thread's JNIEnv so we
2160 // can be here operating on behalf of a suspended thread (4432884).
2161 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2162 JavaThreadState state = thread->thread_state();
2163
2164 // We mark this thread_blocked state as a suspend-equivalent so
2165 // that a caller to is_ext_suspend_completed() won't be confused.
2166 // The suspend-equivalent state is cleared by java_suspend_self().
2167 thread->set_suspend_equivalent();
2168
2169 // If the safepoint code sees the _thread_in_native_trans state, it will
2170 // wait until the thread changes to other thread state. There is no
2171 // guarantee on how soon we can obtain the SR_lock and complete the
2172 // self-suspend request. It would be a bad idea to let safepoint wait for
2173 // too long. Temporarily change the state to _thread_blocked to
2174 // let the VM thread know that this thread is ready for GC. The problem
2175 // of changing thread state is that safepoint could happen just after
2176 // java_suspend_self() returns after being resumed, and VM thread will
2177 // see the _thread_blocked state. We must check for safepoint
2178 // after restoring the state and make sure we won't leave while a safepoint
2179 // is in progress.
2180 thread->set_thread_state(_thread_blocked);
2181 thread->java_suspend_self();
2182 thread->set_thread_state(state);
2183 // Make sure new state is seen by VM thread
2184 if (os::is_MP()) {
2185 if (UseMembar) {
2186 // Force a fence between the write above and read below
2187 OrderAccess::fence();
2188 } else {
2189 // Must use this rather than serialization page in particular on Windows
2190 InterfaceSupport::serialize_memory(thread);
2191 }
2192 }
2193 }
2194
2195 if (SafepointSynchronize::do_call_back()) {
2196 // If we are safepointing, then block the caller which may not be
2197 // the same as the target thread (see above).
2198 SafepointSynchronize::block(curJT);
2199 }
2200
2201 if (thread->is_deopt_suspend()) {
2202 thread->clear_deopt_suspend();
2203 RegisterMap map(thread, false);
2204 frame f = thread->last_frame();
2205 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2206 f = f.sender(&map);
2207 }
2208 if (f.id() == thread->must_deopt_id()) {
2209 thread->clear_must_deopt_id();
2210 f.deoptimize(thread);
2211 } else {
2212 fatal("missed deoptimization!");
2213 }
2214 }
2215 }
2216
2217 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2218 // progress or when _suspend_flags is non-zero.
2219 // Current thread needs to self-suspend if there is a suspend request and/or
2220 // block if a safepoint is in progress.
2221 // Also check for pending async exception (not including unsafe access error).
2222 // Note only the native==>VM/Java barriers can call this function and when
2223 // thread state is _thread_in_native_trans.
2224 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2225 check_safepoint_and_suspend_for_native_trans(thread);
2226
2227 if (thread->has_async_exception()) {
2228 // We are in _thread_in_native_trans state, don't handle unsafe
2229 // access error since that may block.
2230 thread->check_and_handle_async_exceptions(false);
2231 }
2232 }
2233
2234 // We need to guarantee the Threads_lock here, since resumes are not
2235 // allowed during safepoint synchronization
2236 // Can only resume from an external suspension
2237 void JavaThread::java_resume() {
2238 assert_locked_or_safepoint(Threads_lock);
2239
2240 // Sanity check: thread is gone, has started exiting or the thread
2241 // was not externally suspended.
2242 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2243 return;
2244 }
2245
2246 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2247
2248 clear_external_suspend();
2249
2250 if (is_ext_suspended()) {
2251 clear_ext_suspended();
2252 SR_lock()->notify_all();
2253 }
2254 }
2255
2256 void JavaThread::create_stack_guard_pages() {
2257 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2258 address low_addr = stack_base() - stack_size();
2259 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2260
2261 int allocate = os::allocate_stack_guard_pages();
2262 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2263
2264 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2265 warning("Attempt to allocate stack guard pages failed.");
2266 return;
2267 }
2268
2269 if (os::guard_memory((char *) low_addr, len)) {
2270 _stack_guard_state = stack_guard_enabled;
2271 } else {
2272 warning("Attempt to protect stack guard pages failed.");
2273 if (os::uncommit_memory((char *) low_addr, len)) {
2274 warning("Attempt to deallocate stack guard pages failed.");
2275 }
2276 }
2277 }
2278
2279 void JavaThread::remove_stack_guard_pages() {
2280 if (_stack_guard_state == stack_guard_unused) return;
2281 address low_addr = stack_base() - stack_size();
2282 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2283
2284 if (os::allocate_stack_guard_pages()) {
2285 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2286 _stack_guard_state = stack_guard_unused;
2287 } else {
2288 warning("Attempt to deallocate stack guard pages failed.");
2289 }
2290 } else {
2291 if (_stack_guard_state == stack_guard_unused) return;
2292 if (os::unguard_memory((char *) low_addr, len)) {
2293 _stack_guard_state = stack_guard_unused;
2294 } else {
2295 warning("Attempt to unprotect stack guard pages failed.");
2296 }
2297 }
2298 }
2299
2300 void JavaThread::enable_stack_yellow_zone() {
2301 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2302 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2303
2304 // The base notation is from the stacks point of view, growing downward.
2305 // We need to adjust it to work correctly with guard_memory()
2306 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2307
2308 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2309 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2310
2311 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2312 _stack_guard_state = stack_guard_enabled;
2313 } else {
2314 warning("Attempt to guard stack yellow zone failed.");
2315 }
2316 enable_register_stack_guard();
2317 }
2318
2319 void JavaThread::disable_stack_yellow_zone() {
2320 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2321 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2322
2323 // Simply return if called for a thread that does not use guard pages.
2324 if (_stack_guard_state == stack_guard_unused) return;
2325
2326 // The base notation is from the stacks point of view, growing downward.
2327 // We need to adjust it to work correctly with guard_memory()
2328 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2329
2330 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2331 _stack_guard_state = stack_guard_yellow_disabled;
2332 } else {
2333 warning("Attempt to unguard stack yellow zone failed.");
2334 }
2335 disable_register_stack_guard();
2336 }
2337
2338 void JavaThread::enable_stack_red_zone() {
2339 // The base notation is from the stacks point of view, growing downward.
2340 // We need to adjust it to work correctly with guard_memory()
2341 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2342 address base = stack_red_zone_base() - stack_red_zone_size();
2343
2344 guarantee(base < stack_base(),"Error calculating stack red zone");
2345 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2346
2347 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2348 warning("Attempt to guard stack red zone failed.");
2349 }
2350 }
2351
2352 void JavaThread::disable_stack_red_zone() {
2353 // The base notation is from the stacks point of view, growing downward.
2354 // We need to adjust it to work correctly with guard_memory()
2355 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2356 address base = stack_red_zone_base() - stack_red_zone_size();
2357 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2358 warning("Attempt to unguard stack red zone failed.");
2359 }
2360 }
2361
2362 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2363 // ignore is there is no stack
2364 if (!has_last_Java_frame()) return;
2365 // traverse the stack frames. Starts from top frame.
2366 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2367 frame* fr = fst.current();
2368 f(fr, fst.register_map());
2369 }
2370 }
2371
2372
2373 #ifndef PRODUCT
2374 // Deoptimization
2375 // Function for testing deoptimization
2376 void JavaThread::deoptimize() {
2377 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2378 StackFrameStream fst(this, UseBiasedLocking);
2379 bool deopt = false; // Dump stack only if a deopt actually happens.
2380 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2381 // Iterate over all frames in the thread and deoptimize
2382 for(; !fst.is_done(); fst.next()) {
2383 if(fst.current()->can_be_deoptimized()) {
2384
2385 if (only_at) {
2386 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2387 // consists of comma or carriage return separated numbers so
2388 // search for the current bci in that string.
2389 address pc = fst.current()->pc();
2390 nmethod* nm = (nmethod*) fst.current()->cb();
2391 ScopeDesc* sd = nm->scope_desc_at( pc);
2392 char buffer[8];
2393 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2394 size_t len = strlen(buffer);
2395 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2396 while (found != NULL) {
2397 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2398 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2399 // Check that the bci found is bracketed by terminators.
2400 break;
2401 }
2402 found = strstr(found + 1, buffer);
2403 }
2404 if (!found) {
2405 continue;
2406 }
2407 }
2408
2409 if (DebugDeoptimization && !deopt) {
2410 deopt = true; // One-time only print before deopt
2411 tty->print_cr("[BEFORE Deoptimization]");
2412 trace_frames();
2413 trace_stack();
2414 }
2415 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2416 }
2417 }
2418
2419 if (DebugDeoptimization && deopt) {
2420 tty->print_cr("[AFTER Deoptimization]");
2421 trace_frames();
2422 }
2423 }
2424
2425
2426 // Make zombies
2427 void JavaThread::make_zombies() {
2428 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2429 if (fst.current()->can_be_deoptimized()) {
2430 // it is a Java nmethod
2431 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2432 nm->make_not_entrant();
2433 }
2434 }
2435 }
2436 #endif // PRODUCT
2437
2438
2439 void JavaThread::deoptimized_wrt_marked_nmethods() {
2440 if (!has_last_Java_frame()) return;
2441 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2442 StackFrameStream fst(this, UseBiasedLocking);
2443 for(; !fst.is_done(); fst.next()) {
2444 if (fst.current()->should_be_deoptimized()) {
2445 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2446 }
2447 }
2448 }
2449
2450
2451 // GC support
2452 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2453
2454 void JavaThread::gc_epilogue() {
2455 frames_do(frame_gc_epilogue);
2456 }
2457
2458
2459 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2460
2461 void JavaThread::gc_prologue() {
2462 frames_do(frame_gc_prologue);
2463 }
2464
2465 // If the caller is a NamedThread, then remember, in the current scope,
2466 // the given JavaThread in its _processed_thread field.
2467 class RememberProcessedThread: public StackObj {
2468 NamedThread* _cur_thr;
2469 public:
2470 RememberProcessedThread(JavaThread* jthr) {
2471 Thread* thread = Thread::current();
2472 if (thread->is_Named_thread()) {
2473 _cur_thr = (NamedThread *)thread;
2474 _cur_thr->set_processed_thread(jthr);
2475 } else {
2476 _cur_thr = NULL;
2477 }
2478 }
2479
2480 ~RememberProcessedThread() {
2481 if (_cur_thr) {
2482 _cur_thr->set_processed_thread(NULL);
2483 }
2484 }
2485 };
2486
2487 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2488 // Verify that the deferred card marks have been flushed.
2489 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2490
2491 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2492 // since there may be more than one thread using each ThreadProfiler.
2493
2494 // Traverse the GCHandles
2495 Thread::oops_do(f, cf);
2496
2497 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2498 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2499
2500 if (has_last_Java_frame()) {
2501 // Record JavaThread to GC thread
2502 RememberProcessedThread rpt(this);
2503
2504 // Traverse the privileged stack
2505 if (_privileged_stack_top != NULL) {
2506 _privileged_stack_top->oops_do(f);
2507 }
2508
2509 // traverse the registered growable array
2510 if (_array_for_gc != NULL) {
2511 for (int index = 0; index < _array_for_gc->length(); index++) {
2512 f->do_oop(_array_for_gc->adr_at(index));
2513 }
2514 }
2515
2516 // Traverse the monitor chunks
2517 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2518 chunk->oops_do(f);
2519 }
2520
2521 // Traverse the execution stack
2522 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2523 fst.current()->oops_do(f, cf, fst.register_map());
2524 }
2525 }
2526
2527 // callee_target is never live across a gc point so NULL it here should
2528 // it still contain a methdOop.
2529
2530 set_callee_target(NULL);
2531
2532 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2533 // If we have deferred set_locals there might be oops waiting to be
2534 // written
2535 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2536 if (list != NULL) {
2537 for (int i = 0; i < list->length(); i++) {
2538 list->at(i)->oops_do(f);
2539 }
2540 }
2541
2542 // Traverse instance variables at the end since the GC may be moving things
2543 // around using this function
2544 f->do_oop((oop*) &_threadObj);
2545 f->do_oop((oop*) &_vm_result);
2546 f->do_oop((oop*) &_vm_result_2);
2547 f->do_oop((oop*) &_exception_oop);
2548 f->do_oop((oop*) &_pending_async_exception);
2549
2550 if (jvmti_thread_state() != NULL) {
2551 jvmti_thread_state()->oops_do(f);
2552 }
2553 }
2554
2555 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2556 Thread::nmethods_do(cf); // (super method is a no-op)
2557
2558 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2559 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2560
2561 if (has_last_Java_frame()) {
2562 // Traverse the execution stack
2563 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2564 fst.current()->nmethods_do(cf);
2565 }
2566 }
2567 }
2568
2569 // Printing
2570 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2571 switch (_thread_state) {
2572 case _thread_uninitialized: return "_thread_uninitialized";
2573 case _thread_new: return "_thread_new";
2574 case _thread_new_trans: return "_thread_new_trans";
2575 case _thread_in_native: return "_thread_in_native";
2576 case _thread_in_native_trans: return "_thread_in_native_trans";
2577 case _thread_in_vm: return "_thread_in_vm";
2578 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2579 case _thread_in_Java: return "_thread_in_Java";
2580 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2581 case _thread_blocked: return "_thread_blocked";
2582 case _thread_blocked_trans: return "_thread_blocked_trans";
2583 default: return "unknown thread state";
2584 }
2585 }
2586
2587 #ifndef PRODUCT
2588 void JavaThread::print_thread_state_on(outputStream *st) const {
2589 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2590 };
2591 void JavaThread::print_thread_state() const {
2592 print_thread_state_on(tty);
2593 };
2594 #endif // PRODUCT
2595
2596 // Called by Threads::print() for VM_PrintThreads operation
2597 void JavaThread::print_on(outputStream *st) const {
2598 st->print("\"%s\" ", get_thread_name());
2599 oop thread_oop = threadObj();
2600 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2601 Thread::print_on(st);
2602 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2603 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2604 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2605 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2606 }
2607 #ifndef PRODUCT
2608 print_thread_state_on(st);
2609 _safepoint_state->print_on(st);
2610 #endif // PRODUCT
2611 }
2612
2613 // Called by fatal error handler. The difference between this and
2614 // JavaThread::print() is that we can't grab lock or allocate memory.
2615 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2616 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2617 oop thread_obj = threadObj();
2618 if (thread_obj != NULL) {
2619 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2620 }
2621 st->print(" [");
2622 st->print("%s", _get_thread_state_name(_thread_state));
2623 if (osthread()) {
2624 st->print(", id=%d", osthread()->thread_id());
2625 }
2626 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2627 _stack_base - _stack_size, _stack_base);
2628 st->print("]");
2629 return;
2630 }
2631
2632 // Verification
2633
2634 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2635
2636 void JavaThread::verify() {
2637 // Verify oops in the thread.
2638 oops_do(&VerifyOopClosure::verify_oop, NULL);
2639
2640 // Verify the stack frames.
2641 frames_do(frame_verify);
2642 }
2643
2644 // CR 6300358 (sub-CR 2137150)
2645 // Most callers of this method assume that it can't return NULL but a
2646 // thread may not have a name whilst it is in the process of attaching to
2647 // the VM - see CR 6412693, and there are places where a JavaThread can be
2648 // seen prior to having it's threadObj set (eg JNI attaching threads and
2649 // if vm exit occurs during initialization). These cases can all be accounted
2650 // for such that this method never returns NULL.
2651 const char* JavaThread::get_thread_name() const {
2652 #ifdef ASSERT
2653 // early safepoints can hit while current thread does not yet have TLS
2654 if (!SafepointSynchronize::is_at_safepoint()) {
2655 Thread *cur = Thread::current();
2656 if (!(cur->is_Java_thread() && cur == this)) {
2657 // Current JavaThreads are allowed to get their own name without
2658 // the Threads_lock.
2659 assert_locked_or_safepoint(Threads_lock);
2660 }
2661 }
2662 #endif // ASSERT
2663 return get_thread_name_string();
2664 }
2665
2666 // Returns a non-NULL representation of this thread's name, or a suitable
2667 // descriptive string if there is no set name
2668 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2669 const char* name_str;
2670 oop thread_obj = threadObj();
2671 if (thread_obj != NULL) {
2672 typeArrayOop name = java_lang_Thread::name(thread_obj);
2673 if (name != NULL) {
2674 if (buf == NULL) {
2675 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2676 }
2677 else {
2678 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2679 }
2680 }
2681 else if (is_attaching()) { // workaround for 6412693 - see 6404306
2682 name_str = "<no-name - thread is attaching>";
2683 }
2684 else {
2685 name_str = Thread::name();
2686 }
2687 }
2688 else {
2689 name_str = Thread::name();
2690 }
2691 assert(name_str != NULL, "unexpected NULL thread name");
2692 return name_str;
2693 }
2694
2695
2696 const char* JavaThread::get_threadgroup_name() const {
2697 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2698 oop thread_obj = threadObj();
2699 if (thread_obj != NULL) {
2700 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2701 if (thread_group != NULL) {
2702 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2703 // ThreadGroup.name can be null
2704 if (name != NULL) {
2705 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2706 return str;
2707 }
2708 }
2709 }
2710 return NULL;
2711 }
2712
2713 const char* JavaThread::get_parent_name() const {
2714 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2715 oop thread_obj = threadObj();
2716 if (thread_obj != NULL) {
2717 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2718 if (thread_group != NULL) {
2719 oop parent = java_lang_ThreadGroup::parent(thread_group);
2720 if (parent != NULL) {
2721 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2722 // ThreadGroup.name can be null
2723 if (name != NULL) {
2724 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2725 return str;
2726 }
2727 }
2728 }
2729 }
2730 return NULL;
2731 }
2732
2733 ThreadPriority JavaThread::java_priority() const {
2734 oop thr_oop = threadObj();
2735 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2736 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2737 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2738 return priority;
2739 }
2740
2741 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2742
2743 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2744 // Link Java Thread object <-> C++ Thread
2745
2746 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2747 // and put it into a new Handle. The Handle "thread_oop" can then
2748 // be used to pass the C++ thread object to other methods.
2749
2750 // Set the Java level thread object (jthread) field of the
2751 // new thread (a JavaThread *) to C++ thread object using the
2752 // "thread_oop" handle.
2753
2754 // Set the thread field (a JavaThread *) of the
2755 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2756
2757 Handle thread_oop(Thread::current(),
2758 JNIHandles::resolve_non_null(jni_thread));
2759 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2760 "must be initialized");
2761 set_threadObj(thread_oop());
2762 java_lang_Thread::set_thread(thread_oop(), this);
2763
2764 if (prio == NoPriority) {
2765 prio = java_lang_Thread::priority(thread_oop());
2766 assert(prio != NoPriority, "A valid priority should be present");
2767 }
2768
2769 // Push the Java priority down to the native thread; needs Threads_lock
2770 Thread::set_priority(this, prio);
2771
2772 // Add the new thread to the Threads list and set it in motion.
2773 // We must have threads lock in order to call Threads::add.
2774 // It is crucial that we do not block before the thread is
2775 // added to the Threads list for if a GC happens, then the java_thread oop
2776 // will not be visited by GC.
2777 Threads::add(this);
2778 }
2779
2780 oop JavaThread::current_park_blocker() {
2781 // Support for JSR-166 locks
2782 oop thread_oop = threadObj();
2783 if (thread_oop != NULL &&
2784 JDK_Version::current().supports_thread_park_blocker()) {
2785 return java_lang_Thread::park_blocker(thread_oop);
2786 }
2787 return NULL;
2788 }
2789
2790
2791 void JavaThread::print_stack_on(outputStream* st) {
2792 if (!has_last_Java_frame()) return;
2793 ResourceMark rm;
2794 HandleMark hm;
2795
2796 RegisterMap reg_map(this);
2797 vframe* start_vf = last_java_vframe(®_map);
2798 int count = 0;
2799 for (vframe* f = start_vf; f; f = f->sender() ) {
2800 if (f->is_java_frame()) {
2801 javaVFrame* jvf = javaVFrame::cast(f);
2802 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2803
2804 // Print out lock information
2805 if (JavaMonitorsInStackTrace) {
2806 jvf->print_lock_info_on(st, count);
2807 }
2808 } else {
2809 // Ignore non-Java frames
2810 }
2811
2812 // Bail-out case for too deep stacks
2813 count++;
2814 if (MaxJavaStackTraceDepth == count) return;
2815 }
2816 }
2817
2818
2819 // JVMTI PopFrame support
2820 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2821 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2822 if (in_bytes(size_in_bytes) != 0) {
2823 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2824 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2825 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2826 }
2827 }
2828
2829 void* JavaThread::popframe_preserved_args() {
2830 return _popframe_preserved_args;
2831 }
2832
2833 ByteSize JavaThread::popframe_preserved_args_size() {
2834 return in_ByteSize(_popframe_preserved_args_size);
2835 }
2836
2837 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2838 int sz = in_bytes(popframe_preserved_args_size());
2839 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2840 return in_WordSize(sz / wordSize);
2841 }
2842
2843 void JavaThread::popframe_free_preserved_args() {
2844 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2845 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2846 _popframe_preserved_args = NULL;
2847 _popframe_preserved_args_size = 0;
2848 }
2849
2850 #ifndef PRODUCT
2851
2852 void JavaThread::trace_frames() {
2853 tty->print_cr("[Describe stack]");
2854 int frame_no = 1;
2855 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2856 tty->print(" %d. ", frame_no++);
2857 fst.current()->print_value_on(tty,this);
2858 tty->cr();
2859 }
2860 }
2861
2862
2863 void JavaThread::trace_stack_from(vframe* start_vf) {
2864 ResourceMark rm;
2865 int vframe_no = 1;
2866 for (vframe* f = start_vf; f; f = f->sender() ) {
2867 if (f->is_java_frame()) {
2868 javaVFrame::cast(f)->print_activation(vframe_no++);
2869 } else {
2870 f->print();
2871 }
2872 if (vframe_no > StackPrintLimit) {
2873 tty->print_cr("...<more frames>...");
2874 return;
2875 }
2876 }
2877 }
2878
2879
2880 void JavaThread::trace_stack() {
2881 if (!has_last_Java_frame()) return;
2882 ResourceMark rm;
2883 HandleMark hm;
2884 RegisterMap reg_map(this);
2885 trace_stack_from(last_java_vframe(®_map));
2886 }
2887
2888
2889 #endif // PRODUCT
2890
2891
2892 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2893 assert(reg_map != NULL, "a map must be given");
2894 frame f = last_frame();
2895 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2896 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2897 }
2898 return NULL;
2899 }
2900
2901
2902 klassOop JavaThread::security_get_caller_class(int depth) {
2903 vframeStream vfst(this);
2904 vfst.security_get_caller_frame(depth);
2905 if (!vfst.at_end()) {
2906 return vfst.method()->method_holder();
2907 }
2908 return NULL;
2909 }
2910
2911 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2912 assert(thread->is_Compiler_thread(), "must be compiler thread");
2913 CompileBroker::compiler_thread_loop();
2914 }
2915
2916 // Create a CompilerThread
2917 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2918 : JavaThread(&compiler_thread_entry) {
2919 _env = NULL;
2920 _log = NULL;
2921 _task = NULL;
2922 _queue = queue;
2923 _counters = counters;
2924 _buffer_blob = NULL;
2925
2926 #ifndef PRODUCT
2927 _ideal_graph_printer = NULL;
2928 #endif
2929 }
2930
2931
2932 // ======= Threads ========
2933
2934 // The Threads class links together all active threads, and provides
2935 // operations over all threads. It is protected by its own Mutex
2936 // lock, which is also used in other contexts to protect thread
2937 // operations from having the thread being operated on from exiting
2938 // and going away unexpectedly (e.g., safepoint synchronization)
2939
2940 JavaThread* Threads::_thread_list = NULL;
2941 int Threads::_number_of_threads = 0;
2942 int Threads::_number_of_non_daemon_threads = 0;
2943 int Threads::_return_code = 0;
2944 size_t JavaThread::_stack_size_at_create = 0;
2945
2946 // All JavaThreads
2947 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2948
2949 void os_stream();
2950
2951 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2952 void Threads::threads_do(ThreadClosure* tc) {
2953 assert_locked_or_safepoint(Threads_lock);
2954 // ALL_JAVA_THREADS iterates through all JavaThreads
2955 ALL_JAVA_THREADS(p) {
2956 tc->do_thread(p);
2957 }
2958 // Someday we could have a table or list of all non-JavaThreads.
2959 // For now, just manually iterate through them.
2960 tc->do_thread(VMThread::vm_thread());
2961 Universe::heap()->gc_threads_do(tc);
2962 WatcherThread *wt = WatcherThread::watcher_thread();
2963 // Strictly speaking, the following NULL check isn't sufficient to make sure
2964 // the data for WatcherThread is still valid upon being examined. However,
2965 // considering that WatchThread terminates when the VM is on the way to
2966 // exit at safepoint, the chance of the above is extremely small. The right
2967 // way to prevent termination of WatcherThread would be to acquire
2968 // Terminator_lock, but we can't do that without violating the lock rank
2969 // checking in some cases.
2970 if (wt != NULL)
2971 tc->do_thread(wt);
2972
2973 // If CompilerThreads ever become non-JavaThreads, add them here
2974 }
2975
2976 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2977
2978 extern void JDK_Version_init();
2979
2980 // Check version
2981 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2982
2983 // Initialize the output stream module
2984 ostream_init();
2985
2986 // Process java launcher properties.
2987 Arguments::process_sun_java_launcher_properties(args);
2988
2989 // Initialize the os module before using TLS
2990 os::init();
2991
2992 // Initialize system properties.
2993 Arguments::init_system_properties();
2994
2995 // So that JDK version can be used as a discrimintor when parsing arguments
2996 JDK_Version_init();
2997
2998 // Update/Initialize System properties after JDK version number is known
2999 Arguments::init_version_specific_system_properties();
3000
3001 // Parse arguments
3002 jint parse_result = Arguments::parse(args);
3003 if (parse_result != JNI_OK) return parse_result;
3004
3005 if (PauseAtStartup) {
3006 os::pause();
3007 }
3008
3009 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3010
3011 // Record VM creation timing statistics
3012 TraceVmCreationTime create_vm_timer;
3013 create_vm_timer.start();
3014
3015 // Timing (must come after argument parsing)
3016 TraceTime timer("Create VM", TraceStartupTime);
3017
3018 // Initialize the os module after parsing the args
3019 jint os_init_2_result = os::init_2();
3020 if (os_init_2_result != JNI_OK) return os_init_2_result;
3021
3022 // Initialize output stream logging
3023 ostream_init_log();
3024
3025 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3026 // Must be before create_vm_init_agents()
3027 if (Arguments::init_libraries_at_startup()) {
3028 convert_vm_init_libraries_to_agents();
3029 }
3030
3031 // Launch -agentlib/-agentpath and converted -Xrun agents
3032 if (Arguments::init_agents_at_startup()) {
3033 create_vm_init_agents();
3034 }
3035
3036 // Initialize Threads state
3037 _thread_list = NULL;
3038 _number_of_threads = 0;
3039 _number_of_non_daemon_threads = 0;
3040
3041 // Initialize TLS
3042 ThreadLocalStorage::init();
3043
3044 // Initialize global data structures and create system classes in heap
3045 vm_init_globals();
3046
3047 // Attach the main thread to this os thread
3048 JavaThread* main_thread = new JavaThread();
3049 main_thread->set_thread_state(_thread_in_vm);
3050 // must do this before set_active_handles and initialize_thread_local_storage
3051 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3052 // change the stack size recorded here to one based on the java thread
3053 // stacksize. This adjusted size is what is used to figure the placement
3054 // of the guard pages.
3055 main_thread->record_stack_base_and_size();
3056 main_thread->initialize_thread_local_storage();
3057
3058 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3059
3060 if (!main_thread->set_as_starting_thread()) {
3061 vm_shutdown_during_initialization(
3062 "Failed necessary internal allocation. Out of swap space");
3063 delete main_thread;
3064 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3065 return JNI_ENOMEM;
3066 }
3067
3068 // Enable guard page *after* os::create_main_thread(), otherwise it would
3069 // crash Linux VM, see notes in os_linux.cpp.
3070 main_thread->create_stack_guard_pages();
3071
3072 // Initialize Java-Level synchronization subsystem
3073 ObjectMonitor::Initialize() ;
3074
3075 // Initialize global modules
3076 jint status = init_globals();
3077 if (status != JNI_OK) {
3078 delete main_thread;
3079 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3080 return status;
3081 }
3082
3083 // Should be done after the heap is fully created
3084 main_thread->cache_global_variables();
3085
3086 HandleMark hm;
3087
3088 { MutexLocker mu(Threads_lock);
3089 Threads::add(main_thread);
3090 }
3091
3092 // Any JVMTI raw monitors entered in onload will transition into
3093 // real raw monitor. VM is setup enough here for raw monitor enter.
3094 JvmtiExport::transition_pending_onload_raw_monitors();
3095
3096 if (VerifyBeforeGC &&
3097 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3098 Universe::heap()->prepare_for_verify();
3099 Universe::verify(); // make sure we're starting with a clean slate
3100 }
3101
3102 // Create the VMThread
3103 { TraceTime timer("Start VMThread", TraceStartupTime);
3104 VMThread::create();
3105 Thread* vmthread = VMThread::vm_thread();
3106
3107 if (!os::create_thread(vmthread, os::vm_thread))
3108 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3109
3110 // Wait for the VM thread to become ready, and VMThread::run to initialize
3111 // Monitors can have spurious returns, must always check another state flag
3112 {
3113 MutexLocker ml(Notify_lock);
3114 os::start_thread(vmthread);
3115 while (vmthread->active_handles() == NULL) {
3116 Notify_lock->wait();
3117 }
3118 }
3119 }
3120
3121 assert (Universe::is_fully_initialized(), "not initialized");
3122 EXCEPTION_MARK;
3123
3124 // At this point, the Universe is initialized, but we have not executed
3125 // any byte code. Now is a good time (the only time) to dump out the
3126 // internal state of the JVM for sharing.
3127
3128 if (DumpSharedSpaces) {
3129 Universe::heap()->preload_and_dump(CHECK_0);
3130 ShouldNotReachHere();
3131 }
3132
3133 // Always call even when there are not JVMTI environments yet, since environments
3134 // may be attached late and JVMTI must track phases of VM execution
3135 JvmtiExport::enter_start_phase();
3136
3137 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3138 JvmtiExport::post_vm_start();
3139
3140 {
3141 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3142
3143 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3144 create_vm_init_libraries();
3145 }
3146
3147 if (InitializeJavaLangString) {
3148 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3149 } else {
3150 warning("java.lang.String not initialized");
3151 }
3152
3153 if (AggressiveOpts) {
3154 {
3155 // Forcibly initialize java/util/HashMap and mutate the private
3156 // static final "frontCacheEnabled" field before we start creating instances
3157 #ifdef ASSERT
3158 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3159 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3160 #endif
3161 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3162 KlassHandle k = KlassHandle(THREAD, k_o);
3163 guarantee(k.not_null(), "Must find java/util/HashMap");
3164 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3165 ik->initialize(CHECK_0);
3166 fieldDescriptor fd;
3167 // Possible we might not find this field; if so, don't break
3168 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3169 k()->java_mirror()->bool_field_put(fd.offset(), true);
3170 }
3171 }
3172
3173 if (UseStringCache) {
3174 // Forcibly initialize java/lang/StringValue and mutate the private
3175 // static final "stringCacheEnabled" field before we start creating instances
3176 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3177 // Possible that StringValue isn't present: if so, silently don't break
3178 if (k_o != NULL) {
3179 KlassHandle k = KlassHandle(THREAD, k_o);
3180 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3181 ik->initialize(CHECK_0);
3182 fieldDescriptor fd;
3183 // Possible we might not find this field: if so, silently don't break
3184 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3185 k()->java_mirror()->bool_field_put(fd.offset(), true);
3186 }
3187 }
3188 }
3189 }
3190
3191 // Initialize java_lang.System (needed before creating the thread)
3192 if (InitializeJavaLangSystem) {
3193 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3194 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3195 Handle thread_group = create_initial_thread_group(CHECK_0);
3196 Universe::set_main_thread_group(thread_group());
3197 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3198 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3199 main_thread->set_threadObj(thread_object);
3200 // Set thread status to running since main thread has
3201 // been started and running.
3202 java_lang_Thread::set_thread_status(thread_object,
3203 java_lang_Thread::RUNNABLE);
3204
3205 // The VM preresolve methods to these classes. Make sure that get initialized
3206 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3207 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3208 // The VM creates & returns objects of this class. Make sure it's initialized.
3209 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3210 call_initializeSystemClass(CHECK_0);
3211 } else {
3212 warning("java.lang.System not initialized");
3213 }
3214
3215 // an instance of OutOfMemory exception has been allocated earlier
3216 if (InitializeJavaLangExceptionsErrors) {
3217 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3218 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3219 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3220 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3221 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3222 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3223 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3224 } else {
3225 warning("java.lang.OutOfMemoryError has not been initialized");
3226 warning("java.lang.NullPointerException has not been initialized");
3227 warning("java.lang.ClassCastException has not been initialized");
3228 warning("java.lang.ArrayStoreException has not been initialized");
3229 warning("java.lang.ArithmeticException has not been initialized");
3230 warning("java.lang.StackOverflowError has not been initialized");
3231 }
3232 }
3233
3234 // See : bugid 4211085.
3235 // Background : the static initializer of java.lang.Compiler tries to read
3236 // property"java.compiler" and read & write property "java.vm.info".
3237 // When a security manager is installed through the command line
3238 // option "-Djava.security.manager", the above properties are not
3239 // readable and the static initializer for java.lang.Compiler fails
3240 // resulting in a NoClassDefFoundError. This can happen in any
3241 // user code which calls methods in java.lang.Compiler.
3242 // Hack : the hack is to pre-load and initialize this class, so that only
3243 // system domains are on the stack when the properties are read.
3244 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3245 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3246 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3247 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3248 // Once that is done, we should remove this hack.
3249 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3250
3251 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3252 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3253 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3254 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3255 // This should also be taken out as soon as 4211383 gets fixed.
3256 reset_vm_info_property(CHECK_0);
3257
3258 quicken_jni_functions();
3259
3260 // Set flag that basic initialization has completed. Used by exceptions and various
3261 // debug stuff, that does not work until all basic classes have been initialized.
3262 set_init_completed();
3263
3264 HS_DTRACE_PROBE(hotspot, vm__init__end);
3265
3266 // record VM initialization completion time
3267 Management::record_vm_init_completed();
3268
3269 // Compute system loader. Note that this has to occur after set_init_completed, since
3270 // valid exceptions may be thrown in the process.
3271 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3272 // set_init_completed has just been called, causing exceptions not to be shortcut
3273 // anymore. We call vm_exit_during_initialization directly instead.
3274 SystemDictionary::compute_java_system_loader(THREAD);
3275 if (HAS_PENDING_EXCEPTION) {
3276 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3277 }
3278
3279 #ifndef SERIALGC
3280 // Support for ConcurrentMarkSweep. This should be cleaned up
3281 // and better encapsulated. The ugly nested if test would go away
3282 // once things are properly refactored. XXX YSR
3283 if (UseConcMarkSweepGC || UseG1GC) {
3284 if (UseConcMarkSweepGC) {
3285 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3286 } else {
3287 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3288 }
3289 if (HAS_PENDING_EXCEPTION) {
3290 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3291 }
3292 }
3293 #endif // SERIALGC
3294
3295 // Always call even when there are not JVMTI environments yet, since environments
3296 // may be attached late and JVMTI must track phases of VM execution
3297 JvmtiExport::enter_live_phase();
3298
3299 // Signal Dispatcher needs to be started before VMInit event is posted
3300 os::signal_init();
3301
3302 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3303 if (!DisableAttachMechanism) {
3304 if (StartAttachListener || AttachListener::init_at_startup()) {
3305 AttachListener::init();
3306 }
3307 }
3308
3309 // Launch -Xrun agents
3310 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3311 // back-end can launch with -Xdebug -Xrunjdwp.
3312 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3313 create_vm_init_libraries();
3314 }
3315
3316 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3317 JvmtiExport::post_vm_initialized();
3318
3319 Chunk::start_chunk_pool_cleaner_task();
3320
3321 // initialize compiler(s)
3322 CompileBroker::compilation_init();
3323
3324 Management::initialize(THREAD);
3325 if (HAS_PENDING_EXCEPTION) {
3326 // management agent fails to start possibly due to
3327 // configuration problem and is responsible for printing
3328 // stack trace if appropriate. Simply exit VM.
3329 vm_exit(1);
3330 }
3331
3332 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3333 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3334 if (MemProfiling) MemProfiler::engage();
3335 StatSampler::engage();
3336 if (CheckJNICalls) JniPeriodicChecker::engage();
3337
3338 BiasedLocking::init();
3339
3340 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3341 call_postVMInitHook(THREAD);
3342 // The Java side of PostVMInitHook.run must deal with all
3343 // exceptions and provide means of diagnosis.
3344 if (HAS_PENDING_EXCEPTION) {
3345 CLEAR_PENDING_EXCEPTION;
3346 }
3347 }
3348
3349 // Start up the WatcherThread if there are any periodic tasks
3350 // NOTE: All PeriodicTasks should be registered by now. If they
3351 // aren't, late joiners might appear to start slowly (we might
3352 // take a while to process their first tick).
3353 if (PeriodicTask::num_tasks() > 0) {
3354 WatcherThread::start();
3355 }
3356
3357 // Give os specific code one last chance to start
3358 os::init_3();
3359
3360 create_vm_timer.end();
3361 return JNI_OK;
3362 }
3363
3364 // type for the Agent_OnLoad and JVM_OnLoad entry points
3365 extern "C" {
3366 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3367 }
3368 // Find a command line agent library and return its entry point for
3369 // -agentlib: -agentpath: -Xrun
3370 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3371 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3372 OnLoadEntry_t on_load_entry = NULL;
3373 void *library = agent->os_lib(); // check if we have looked it up before
3374
3375 if (library == NULL) {
3376 char buffer[JVM_MAXPATHLEN];
3377 char ebuf[1024];
3378 const char *name = agent->name();
3379 const char *msg = "Could not find agent library ";
3380
3381 if (agent->is_absolute_path()) {
3382 library = os::dll_load(name, ebuf, sizeof ebuf);
3383 if (library == NULL) {
3384 const char *sub_msg = " in absolute path, with error: ";
3385 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3386 char *buf = NEW_C_HEAP_ARRAY(char, len);
3387 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3388 // If we can't find the agent, exit.
3389 vm_exit_during_initialization(buf, NULL);
3390 FREE_C_HEAP_ARRAY(char, buf);
3391 }
3392 } else {
3393 // Try to load the agent from the standard dll directory
3394 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3395 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3396 #ifdef KERNEL
3397 // Download instrument dll
3398 if (library == NULL && strcmp(name, "instrument") == 0) {
3399 char *props = Arguments::get_kernel_properties();
3400 char *home = Arguments::get_java_home();
3401 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3402 " sun.jkernel.DownloadManager -download client_jvm";
3403 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3404 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3405 jio_snprintf(cmd, length, fmt, home, props);
3406 int status = os::fork_and_exec(cmd);
3407 FreeHeap(props);
3408 if (status == -1) {
3409 warning(cmd);
3410 vm_exit_during_initialization("fork_and_exec failed: %s",
3411 strerror(errno));
3412 }
3413 FREE_C_HEAP_ARRAY(char, cmd);
3414 // when this comes back the instrument.dll should be where it belongs.
3415 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3416 }
3417 #endif // KERNEL
3418 if (library == NULL) { // Try the local directory
3419 char ns[1] = {0};
3420 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3421 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3422 if (library == NULL) {
3423 const char *sub_msg = " on the library path, with error: ";
3424 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3425 char *buf = NEW_C_HEAP_ARRAY(char, len);
3426 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3427 // If we can't find the agent, exit.
3428 vm_exit_during_initialization(buf, NULL);
3429 FREE_C_HEAP_ARRAY(char, buf);
3430 }
3431 }
3432 }
3433 agent->set_os_lib(library);
3434 }
3435
3436 // Find the OnLoad function.
3437 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3438 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3439 if (on_load_entry != NULL) break;
3440 }
3441 return on_load_entry;
3442 }
3443
3444 // Find the JVM_OnLoad entry point
3445 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3446 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3447 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3448 }
3449
3450 // Find the Agent_OnLoad entry point
3451 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3452 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3453 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3454 }
3455
3456 // For backwards compatibility with -Xrun
3457 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3458 // treated like -agentpath:
3459 // Must be called before agent libraries are created
3460 void Threads::convert_vm_init_libraries_to_agents() {
3461 AgentLibrary* agent;
3462 AgentLibrary* next;
3463
3464 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3465 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3466 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3467
3468 // If there is an JVM_OnLoad function it will get called later,
3469 // otherwise see if there is an Agent_OnLoad
3470 if (on_load_entry == NULL) {
3471 on_load_entry = lookup_agent_on_load(agent);
3472 if (on_load_entry != NULL) {
3473 // switch it to the agent list -- so that Agent_OnLoad will be called,
3474 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3475 Arguments::convert_library_to_agent(agent);
3476 } else {
3477 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3478 }
3479 }
3480 }
3481 }
3482
3483 // Create agents for -agentlib: -agentpath: and converted -Xrun
3484 // Invokes Agent_OnLoad
3485 // Called very early -- before JavaThreads exist
3486 void Threads::create_vm_init_agents() {
3487 extern struct JavaVM_ main_vm;
3488 AgentLibrary* agent;
3489
3490 JvmtiExport::enter_onload_phase();
3491 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3492 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3493
3494 if (on_load_entry != NULL) {
3495 // Invoke the Agent_OnLoad function
3496 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3497 if (err != JNI_OK) {
3498 vm_exit_during_initialization("agent library failed to init", agent->name());
3499 }
3500 } else {
3501 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3502 }
3503 }
3504 JvmtiExport::enter_primordial_phase();
3505 }
3506
3507 extern "C" {
3508 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3509 }
3510
3511 void Threads::shutdown_vm_agents() {
3512 // Send any Agent_OnUnload notifications
3513 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3514 extern struct JavaVM_ main_vm;
3515 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3516
3517 // Find the Agent_OnUnload function.
3518 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3519 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3520 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3521
3522 // Invoke the Agent_OnUnload function
3523 if (unload_entry != NULL) {
3524 JavaThread* thread = JavaThread::current();
3525 ThreadToNativeFromVM ttn(thread);
3526 HandleMark hm(thread);
3527 (*unload_entry)(&main_vm);
3528 break;
3529 }
3530 }
3531 }
3532 }
3533
3534 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3535 // Invokes JVM_OnLoad
3536 void Threads::create_vm_init_libraries() {
3537 extern struct JavaVM_ main_vm;
3538 AgentLibrary* agent;
3539
3540 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3541 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3542
3543 if (on_load_entry != NULL) {
3544 // Invoke the JVM_OnLoad function
3545 JavaThread* thread = JavaThread::current();
3546 ThreadToNativeFromVM ttn(thread);
3547 HandleMark hm(thread);
3548 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3549 if (err != JNI_OK) {
3550 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3551 }
3552 } else {
3553 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3554 }
3555 }
3556 }
3557
3558 // Last thread running calls java.lang.Shutdown.shutdown()
3559 void JavaThread::invoke_shutdown_hooks() {
3560 HandleMark hm(this);
3561
3562 // We could get here with a pending exception, if so clear it now.
3563 if (this->has_pending_exception()) {
3564 this->clear_pending_exception();
3565 }
3566
3567 EXCEPTION_MARK;
3568 klassOop k =
3569 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3570 THREAD);
3571 if (k != NULL) {
3572 // SystemDictionary::resolve_or_null will return null if there was
3573 // an exception. If we cannot load the Shutdown class, just don't
3574 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3575 // and finalizers (if runFinalizersOnExit is set) won't be run.
3576 // Note that if a shutdown hook was registered or runFinalizersOnExit
3577 // was called, the Shutdown class would have already been loaded
3578 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3579 instanceKlassHandle shutdown_klass (THREAD, k);
3580 JavaValue result(T_VOID);
3581 JavaCalls::call_static(&result,
3582 shutdown_klass,
3583 vmSymbols::shutdown_method_name(),
3584 vmSymbols::void_method_signature(),
3585 THREAD);
3586 }
3587 CLEAR_PENDING_EXCEPTION;
3588 }
3589
3590 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3591 // the program falls off the end of main(). Another VM exit path is through
3592 // vm_exit() when the program calls System.exit() to return a value or when
3593 // there is a serious error in VM. The two shutdown paths are not exactly
3594 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3595 // and VM_Exit op at VM level.
3596 //
3597 // Shutdown sequence:
3598 // + Wait until we are the last non-daemon thread to execute
3599 // <-- every thing is still working at this moment -->
3600 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3601 // shutdown hooks, run finalizers if finalization-on-exit
3602 // + Call before_exit(), prepare for VM exit
3603 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3604 // currently the only user of this mechanism is File.deleteOnExit())
3605 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3606 // post thread end and vm death events to JVMTI,
3607 // stop signal thread
3608 // + Call JavaThread::exit(), it will:
3609 // > release JNI handle blocks, remove stack guard pages
3610 // > remove this thread from Threads list
3611 // <-- no more Java code from this thread after this point -->
3612 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3613 // the compiler threads at safepoint
3614 // <-- do not use anything that could get blocked by Safepoint -->
3615 // + Disable tracing at JNI/JVM barriers
3616 // + Set _vm_exited flag for threads that are still running native code
3617 // + Delete this thread
3618 // + Call exit_globals()
3619 // > deletes tty
3620 // > deletes PerfMemory resources
3621 // + Return to caller
3622
3623 bool Threads::destroy_vm() {
3624 JavaThread* thread = JavaThread::current();
3625
3626 // Wait until we are the last non-daemon thread to execute
3627 { MutexLocker nu(Threads_lock);
3628 while (Threads::number_of_non_daemon_threads() > 1 )
3629 // This wait should make safepoint checks, wait without a timeout,
3630 // and wait as a suspend-equivalent condition.
3631 //
3632 // Note: If the FlatProfiler is running and this thread is waiting
3633 // for another non-daemon thread to finish, then the FlatProfiler
3634 // is waiting for the external suspend request on this thread to
3635 // complete. wait_for_ext_suspend_completion() will eventually
3636 // timeout, but that takes time. Making this wait a suspend-
3637 // equivalent condition solves that timeout problem.
3638 //
3639 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3640 Mutex::_as_suspend_equivalent_flag);
3641 }
3642
3643 // Hang forever on exit if we are reporting an error.
3644 if (ShowMessageBoxOnError && is_error_reported()) {
3645 os::infinite_sleep();
3646 }
3647 os::wait_for_keypress_at_exit();
3648
3649 if (JDK_Version::is_jdk12x_version()) {
3650 // We are the last thread running, so check if finalizers should be run.
3651 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3652 HandleMark rm(thread);
3653 Universe::run_finalizers_on_exit();
3654 } else {
3655 // run Java level shutdown hooks
3656 thread->invoke_shutdown_hooks();
3657 }
3658
3659 before_exit(thread);
3660
3661 thread->exit(true);
3662
3663 // Stop VM thread.
3664 {
3665 // 4945125 The vm thread comes to a safepoint during exit.
3666 // GC vm_operations can get caught at the safepoint, and the
3667 // heap is unparseable if they are caught. Grab the Heap_lock
3668 // to prevent this. The GC vm_operations will not be able to
3669 // queue until after the vm thread is dead.
3670 MutexLocker ml(Heap_lock);
3671
3672 VMThread::wait_for_vm_thread_exit();
3673 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3674 VMThread::destroy();
3675 }
3676
3677 // clean up ideal graph printers
3678 #if defined(COMPILER2) && !defined(PRODUCT)
3679 IdealGraphPrinter::clean_up();
3680 #endif
3681
3682 // Now, all Java threads are gone except daemon threads. Daemon threads
3683 // running Java code or in VM are stopped by the Safepoint. However,
3684 // daemon threads executing native code are still running. But they
3685 // will be stopped at native=>Java/VM barriers. Note that we can't
3686 // simply kill or suspend them, as it is inherently deadlock-prone.
3687
3688 #ifndef PRODUCT
3689 // disable function tracing at JNI/JVM barriers
3690 TraceJNICalls = false;
3691 TraceJVMCalls = false;
3692 TraceRuntimeCalls = false;
3693 #endif
3694
3695 VM_Exit::set_vm_exited();
3696
3697 notify_vm_shutdown();
3698
3699 delete thread;
3700
3701 // exit_globals() will delete tty
3702 exit_globals();
3703
3704 return true;
3705 }
3706
3707
3708 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3709 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3710 return is_supported_jni_version(version);
3711 }
3712
3713
3714 jboolean Threads::is_supported_jni_version(jint version) {
3715 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3716 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3717 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3718 return JNI_FALSE;
3719 }
3720
3721
3722 void Threads::add(JavaThread* p, bool force_daemon) {
3723 // The threads lock must be owned at this point
3724 assert_locked_or_safepoint(Threads_lock);
3725
3726 // See the comment for this method in thread.hpp for its purpose and
3727 // why it is called here.
3728 p->initialize_queues();
3729 p->set_next(_thread_list);
3730 _thread_list = p;
3731 _number_of_threads++;
3732 oop threadObj = p->threadObj();
3733 bool daemon = true;
3734 // Bootstrapping problem: threadObj can be null for initial
3735 // JavaThread (or for threads attached via JNI)
3736 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3737 _number_of_non_daemon_threads++;
3738 daemon = false;
3739 }
3740
3741 ThreadService::add_thread(p, daemon);
3742
3743 // Possible GC point.
3744 Events::log("Thread added: " INTPTR_FORMAT, p);
3745 }
3746
3747 void Threads::remove(JavaThread* p) {
3748 // Extra scope needed for Thread_lock, so we can check
3749 // that we do not remove thread without safepoint code notice
3750 { MutexLocker ml(Threads_lock);
3751
3752 assert(includes(p), "p must be present");
3753
3754 JavaThread* current = _thread_list;
3755 JavaThread* prev = NULL;
3756
3757 while (current != p) {
3758 prev = current;
3759 current = current->next();
3760 }
3761
3762 if (prev) {
3763 prev->set_next(current->next());
3764 } else {
3765 _thread_list = p->next();
3766 }
3767 _number_of_threads--;
3768 oop threadObj = p->threadObj();
3769 bool daemon = true;
3770 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3771 _number_of_non_daemon_threads--;
3772 daemon = false;
3773
3774 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3775 // on destroy_vm will wake up.
3776 if (number_of_non_daemon_threads() == 1)
3777 Threads_lock->notify_all();
3778 }
3779 ThreadService::remove_thread(p, daemon);
3780
3781 // Make sure that safepoint code disregard this thread. This is needed since
3782 // the thread might mess around with locks after this point. This can cause it
3783 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3784 // of this thread since it is removed from the queue.
3785 p->set_terminated_value();
3786 } // unlock Threads_lock
3787
3788 // Since Events::log uses a lock, we grab it outside the Threads_lock
3789 Events::log("Thread exited: " INTPTR_FORMAT, p);
3790 }
3791
3792 // Threads_lock must be held when this is called (or must be called during a safepoint)
3793 bool Threads::includes(JavaThread* p) {
3794 assert(Threads_lock->is_locked(), "sanity check");
3795 ALL_JAVA_THREADS(q) {
3796 if (q == p ) {
3797 return true;
3798 }
3799 }
3800 return false;
3801 }
3802
3803 // Operations on the Threads list for GC. These are not explicitly locked,
3804 // but the garbage collector must provide a safe context for them to run.
3805 // In particular, these things should never be called when the Threads_lock
3806 // is held by some other thread. (Note: the Safepoint abstraction also
3807 // uses the Threads_lock to gurantee this property. It also makes sure that
3808 // all threads gets blocked when exiting or starting).
3809
3810 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3811 ALL_JAVA_THREADS(p) {
3812 p->oops_do(f, cf);
3813 }
3814 VMThread::vm_thread()->oops_do(f, cf);
3815 }
3816
3817 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3818 // Introduce a mechanism allowing parallel threads to claim threads as
3819 // root groups. Overhead should be small enough to use all the time,
3820 // even in sequential code.
3821 SharedHeap* sh = SharedHeap::heap();
3822 bool is_par = (sh->n_par_threads() > 0);
3823 int cp = SharedHeap::heap()->strong_roots_parity();
3824 ALL_JAVA_THREADS(p) {
3825 if (p->claim_oops_do(is_par, cp)) {
3826 p->oops_do(f, cf);
3827 }
3828 }
3829 VMThread* vmt = VMThread::vm_thread();
3830 if (vmt->claim_oops_do(is_par, cp))
3831 vmt->oops_do(f, cf);
3832 }
3833
3834 #ifndef SERIALGC
3835 // Used by ParallelScavenge
3836 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3837 ALL_JAVA_THREADS(p) {
3838 q->enqueue(new ThreadRootsTask(p));
3839 }
3840 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3841 }
3842
3843 // Used by Parallel Old
3844 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3845 ALL_JAVA_THREADS(p) {
3846 q->enqueue(new ThreadRootsMarkingTask(p));
3847 }
3848 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3849 }
3850 #endif // SERIALGC
3851
3852 void Threads::nmethods_do(CodeBlobClosure* cf) {
3853 ALL_JAVA_THREADS(p) {
3854 p->nmethods_do(cf);
3855 }
3856 VMThread::vm_thread()->nmethods_do(cf);
3857 }
3858
3859 void Threads::gc_epilogue() {
3860 ALL_JAVA_THREADS(p) {
3861 p->gc_epilogue();
3862 }
3863 }
3864
3865 void Threads::gc_prologue() {
3866 ALL_JAVA_THREADS(p) {
3867 p->gc_prologue();
3868 }
3869 }
3870
3871 void Threads::deoptimized_wrt_marked_nmethods() {
3872 ALL_JAVA_THREADS(p) {
3873 p->deoptimized_wrt_marked_nmethods();
3874 }
3875 }
3876
3877
3878 // Get count Java threads that are waiting to enter the specified monitor.
3879 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3880 address monitor, bool doLock) {
3881 assert(doLock || SafepointSynchronize::is_at_safepoint(),
3882 "must grab Threads_lock or be at safepoint");
3883 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3884
3885 int i = 0;
3886 {
3887 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3888 ALL_JAVA_THREADS(p) {
3889 if (p->is_Compiler_thread()) continue;
3890
3891 address pending = (address)p->current_pending_monitor();
3892 if (pending == monitor) { // found a match
3893 if (i < count) result->append(p); // save the first count matches
3894 i++;
3895 }
3896 }
3897 }
3898 return result;
3899 }
3900
3901
3902 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3903 assert(doLock ||
3904 Threads_lock->owned_by_self() ||
3905 SafepointSynchronize::is_at_safepoint(),
3906 "must grab Threads_lock or be at safepoint");
3907
3908 // NULL owner means not locked so we can skip the search
3909 if (owner == NULL) return NULL;
3910
3911 {
3912 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3913 ALL_JAVA_THREADS(p) {
3914 // first, see if owner is the address of a Java thread
3915 if (owner == (address)p) return p;
3916 }
3917 }
3918 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3919 if (UseHeavyMonitors) return NULL;
3920
3921 //
3922 // If we didn't find a matching Java thread and we didn't force use of
3923 // heavyweight monitors, then the owner is the stack address of the
3924 // Lock Word in the owning Java thread's stack.
3925 //
3926 JavaThread* the_owner = NULL;
3927 {
3928 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3929 ALL_JAVA_THREADS(q) {
3930 if (q->is_lock_owned(owner)) {
3931 the_owner = q;
3932 break;
3933 }
3934 }
3935 }
3936 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3937 return the_owner;
3938 }
3939
3940 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3941 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3942 char buf[32];
3943 st->print_cr(os::local_time_string(buf, sizeof(buf)));
3944
3945 st->print_cr("Full thread dump %s (%s %s):",
3946 Abstract_VM_Version::vm_name(),
3947 Abstract_VM_Version::vm_release(),
3948 Abstract_VM_Version::vm_info_string()
3949 );
3950 st->cr();
3951
3952 #ifndef SERIALGC
3953 // Dump concurrent locks
3954 ConcurrentLocksDump concurrent_locks;
3955 if (print_concurrent_locks) {
3956 concurrent_locks.dump_at_safepoint();
3957 }
3958 #endif // SERIALGC
3959
3960 ALL_JAVA_THREADS(p) {
3961 ResourceMark rm;
3962 p->print_on(st);
3963 if (print_stacks) {
3964 if (internal_format) {
3965 p->trace_stack();
3966 } else {
3967 p->print_stack_on(st);
3968 }
3969 }
3970 st->cr();
3971 #ifndef SERIALGC
3972 if (print_concurrent_locks) {
3973 concurrent_locks.print_locks_on(p, st);
3974 }
3975 #endif // SERIALGC
3976 }
3977
3978 VMThread::vm_thread()->print_on(st);
3979 st->cr();
3980 Universe::heap()->print_gc_threads_on(st);
3981 WatcherThread* wt = WatcherThread::watcher_thread();
3982 if (wt != NULL) wt->print_on(st);
3983 st->cr();
3984 CompileBroker::print_compiler_threads_on(st);
3985 st->flush();
3986 }
3987
3988 // Threads::print_on_error() is called by fatal error handler. It's possible
3989 // that VM is not at safepoint and/or current thread is inside signal handler.
3990 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3991 // memory (even in resource area), it might deadlock the error handler.
3992 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
3993 bool found_current = false;
3994 st->print_cr("Java Threads: ( => current thread )");
3995 ALL_JAVA_THREADS(thread) {
3996 bool is_current = (current == thread);
3997 found_current = found_current || is_current;
3998
3999 st->print("%s", is_current ? "=>" : " ");
4000
4001 st->print(PTR_FORMAT, thread);
4002 st->print(" ");
4003 thread->print_on_error(st, buf, buflen);
4004 st->cr();
4005 }
4006 st->cr();
4007
4008 st->print_cr("Other Threads:");
4009 if (VMThread::vm_thread()) {
4010 bool is_current = (current == VMThread::vm_thread());
4011 found_current = found_current || is_current;
4012 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4013
4014 st->print(PTR_FORMAT, VMThread::vm_thread());
4015 st->print(" ");
4016 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4017 st->cr();
4018 }
4019 WatcherThread* wt = WatcherThread::watcher_thread();
4020 if (wt != NULL) {
4021 bool is_current = (current == wt);
4022 found_current = found_current || is_current;
4023 st->print("%s", is_current ? "=>" : " ");
4024
4025 st->print(PTR_FORMAT, wt);
4026 st->print(" ");
4027 wt->print_on_error(st, buf, buflen);
4028 st->cr();
4029 }
4030 if (!found_current) {
4031 st->cr();
4032 st->print("=>" PTR_FORMAT " (exited) ", current);
4033 current->print_on_error(st, buf, buflen);
4034 st->cr();
4035 }
4036 }
4037
4038 // Internal SpinLock and Mutex
4039 // Based on ParkEvent
4040
4041 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4042 //
4043 // We employ SpinLocks _only for low-contention, fixed-length
4044 // short-duration critical sections where we're concerned
4045 // about native mutex_t or HotSpot Mutex:: latency.
4046 // The mux construct provides a spin-then-block mutual exclusion
4047 // mechanism.
4048 //
4049 // Testing has shown that contention on the ListLock guarding gFreeList
4050 // is common. If we implement ListLock as a simple SpinLock it's common
4051 // for the JVM to devolve to yielding with little progress. This is true
4052 // despite the fact that the critical sections protected by ListLock are
4053 // extremely short.
4054 //
4055 // TODO-FIXME: ListLock should be of type SpinLock.
4056 // We should make this a 1st-class type, integrated into the lock
4057 // hierarchy as leaf-locks. Critically, the SpinLock structure
4058 // should have sufficient padding to avoid false-sharing and excessive
4059 // cache-coherency traffic.
4060
4061
4062 typedef volatile int SpinLockT ;
4063
4064 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4065 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4066 return ; // normal fast-path return
4067 }
4068
4069 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4070 TEVENT (SpinAcquire - ctx) ;
4071 int ctr = 0 ;
4072 int Yields = 0 ;
4073 for (;;) {
4074 while (*adr != 0) {
4075 ++ctr ;
4076 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4077 if (Yields > 5) {
4078 // Consider using a simple NakedSleep() instead.
4079 // Then SpinAcquire could be called by non-JVM threads
4080 Thread::current()->_ParkEvent->park(1) ;
4081 } else {
4082 os::NakedYield() ;
4083 ++Yields ;
4084 }
4085 } else {
4086 SpinPause() ;
4087 }
4088 }
4089 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4090 }
4091 }
4092
4093 void Thread::SpinRelease (volatile int * adr) {
4094 assert (*adr != 0, "invariant") ;
4095 OrderAccess::fence() ; // guarantee at least release consistency.
4096 // Roach-motel semantics.
4097 // It's safe if subsequent LDs and STs float "up" into the critical section,
4098 // but prior LDs and STs within the critical section can't be allowed
4099 // to reorder or float past the ST that releases the lock.
4100 *adr = 0 ;
4101 }
4102
4103 // muxAcquire and muxRelease:
4104 //
4105 // * muxAcquire and muxRelease support a single-word lock-word construct.
4106 // The LSB of the word is set IFF the lock is held.
4107 // The remainder of the word points to the head of a singly-linked list
4108 // of threads blocked on the lock.
4109 //
4110 // * The current implementation of muxAcquire-muxRelease uses its own
4111 // dedicated Thread._MuxEvent instance. If we're interested in
4112 // minimizing the peak number of extant ParkEvent instances then
4113 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4114 // as certain invariants were satisfied. Specifically, care would need
4115 // to be taken with regards to consuming unpark() "permits".
4116 // A safe rule of thumb is that a thread would never call muxAcquire()
4117 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4118 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4119 // consume an unpark() permit intended for monitorenter, for instance.
4120 // One way around this would be to widen the restricted-range semaphore
4121 // implemented in park(). Another alternative would be to provide
4122 // multiple instances of the PlatformEvent() for each thread. One
4123 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4124 //
4125 // * Usage:
4126 // -- Only as leaf locks
4127 // -- for short-term locking only as muxAcquire does not perform
4128 // thread state transitions.
4129 //
4130 // Alternatives:
4131 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4132 // but with parking or spin-then-park instead of pure spinning.
4133 // * Use Taura-Oyama-Yonenzawa locks.
4134 // * It's possible to construct a 1-0 lock if we encode the lockword as
4135 // (List,LockByte). Acquire will CAS the full lockword while Release
4136 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4137 // acquiring threads use timers (ParkTimed) to detect and recover from
4138 // the stranding window. Thread/Node structures must be aligned on 256-byte
4139 // boundaries by using placement-new.
4140 // * Augment MCS with advisory back-link fields maintained with CAS().
4141 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4142 // The validity of the backlinks must be ratified before we trust the value.
4143 // If the backlinks are invalid the exiting thread must back-track through the
4144 // the forward links, which are always trustworthy.
4145 // * Add a successor indication. The LockWord is currently encoded as
4146 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4147 // to provide the usual futile-wakeup optimization.
4148 // See RTStt for details.
4149 // * Consider schedctl.sc_nopreempt to cover the critical section.
4150 //
4151
4152
4153 typedef volatile intptr_t MutexT ; // Mux Lock-word
4154 enum MuxBits { LOCKBIT = 1 } ;
4155
4156 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4157 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4158 if (w == 0) return ;
4159 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4160 return ;
4161 }
4162
4163 TEVENT (muxAcquire - Contention) ;
4164 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4165 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4166 for (;;) {
4167 int its = (os::is_MP() ? 100 : 0) + 1 ;
4168
4169 // Optional spin phase: spin-then-park strategy
4170 while (--its >= 0) {
4171 w = *Lock ;
4172 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4173 return ;
4174 }
4175 }
4176
4177 Self->reset() ;
4178 Self->OnList = intptr_t(Lock) ;
4179 // The following fence() isn't _strictly necessary as the subsequent
4180 // CAS() both serializes execution and ratifies the fetched *Lock value.
4181 OrderAccess::fence();
4182 for (;;) {
4183 w = *Lock ;
4184 if ((w & LOCKBIT) == 0) {
4185 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4186 Self->OnList = 0 ; // hygiene - allows stronger asserts
4187 return ;
4188 }
4189 continue ; // Interference -- *Lock changed -- Just retry
4190 }
4191 assert (w & LOCKBIT, "invariant") ;
4192 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4193 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4194 }
4195
4196 while (Self->OnList != 0) {
4197 Self->park() ;
4198 }
4199 }
4200 }
4201
4202 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4203 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4204 if (w == 0) return ;
4205 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4206 return ;
4207 }
4208
4209 TEVENT (muxAcquire - Contention) ;
4210 ParkEvent * ReleaseAfter = NULL ;
4211 if (ev == NULL) {
4212 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4213 }
4214 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4215 for (;;) {
4216 guarantee (ev->OnList == 0, "invariant") ;
4217 int its = (os::is_MP() ? 100 : 0) + 1 ;
4218
4219 // Optional spin phase: spin-then-park strategy
4220 while (--its >= 0) {
4221 w = *Lock ;
4222 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4223 if (ReleaseAfter != NULL) {
4224 ParkEvent::Release (ReleaseAfter) ;
4225 }
4226 return ;
4227 }
4228 }
4229
4230 ev->reset() ;
4231 ev->OnList = intptr_t(Lock) ;
4232 // The following fence() isn't _strictly necessary as the subsequent
4233 // CAS() both serializes execution and ratifies the fetched *Lock value.
4234 OrderAccess::fence();
4235 for (;;) {
4236 w = *Lock ;
4237 if ((w & LOCKBIT) == 0) {
4238 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4239 ev->OnList = 0 ;
4240 // We call ::Release while holding the outer lock, thus
4241 // artificially lengthening the critical section.
4242 // Consider deferring the ::Release() until the subsequent unlock(),
4243 // after we've dropped the outer lock.
4244 if (ReleaseAfter != NULL) {
4245 ParkEvent::Release (ReleaseAfter) ;
4246 }
4247 return ;
4248 }
4249 continue ; // Interference -- *Lock changed -- Just retry
4250 }
4251 assert (w & LOCKBIT, "invariant") ;
4252 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4253 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4254 }
4255
4256 while (ev->OnList != 0) {
4257 ev->park() ;
4258 }
4259 }
4260 }
4261
4262 // Release() must extract a successor from the list and then wake that thread.
4263 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4264 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4265 // Release() would :
4266 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4267 // (B) Extract a successor from the private list "in-hand"
4268 // (C) attempt to CAS() the residual back into *Lock over null.
4269 // If there were any newly arrived threads and the CAS() would fail.
4270 // In that case Release() would detach the RATs, re-merge the list in-hand
4271 // with the RATs and repeat as needed. Alternately, Release() might
4272 // detach and extract a successor, but then pass the residual list to the wakee.
4273 // The wakee would be responsible for reattaching and remerging before it
4274 // competed for the lock.
4275 //
4276 // Both "pop" and DMR are immune from ABA corruption -- there can be
4277 // multiple concurrent pushers, but only one popper or detacher.
4278 // This implementation pops from the head of the list. This is unfair,
4279 // but tends to provide excellent throughput as hot threads remain hot.
4280 // (We wake recently run threads first).
4281
4282 void Thread::muxRelease (volatile intptr_t * Lock) {
4283 for (;;) {
4284 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4285 assert (w & LOCKBIT, "invariant") ;
4286 if (w == LOCKBIT) return ;
4287 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4288 assert (List != NULL, "invariant") ;
4289 assert (List->OnList == intptr_t(Lock), "invariant") ;
4290 ParkEvent * nxt = List->ListNext ;
4291
4292 // The following CAS() releases the lock and pops the head element.
4293 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4294 continue ;
4295 }
4296 List->OnList = 0 ;
4297 OrderAccess::fence() ;
4298 List->unpark () ;
4299 return ;
4300 }
4301 }
4302
4303
4304 void Threads::verify() {
4305 ALL_JAVA_THREADS(p) {
4306 p->verify();
4307 }
4308 VMThread* thread = VMThread::vm_thread();
4309 if (thread != NULL) thread->verify();
4310 }