1 /*
2 * Copyright (c) 1997, 2010, 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 "memory/oopFactory.hpp"
35 #include "memory/universe.inline.hpp"
36 #include "oops/instanceKlass.hpp"
37 #include "oops/objArrayOop.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "oops/symbolOop.hpp"
40 #include "prims/jvm_misc.hpp"
41 #include "prims/jvmtiExport.hpp"
42 #include "prims/jvmtiThreadState.hpp"
43 #include "prims/privilegedStack.hpp"
44 #include "runtime/aprofiler.hpp"
45 #include "runtime/arguments.hpp"
46 #include "runtime/biasedLocking.hpp"
47 #include "runtime/deoptimization.hpp"
48 #include "runtime/fprofiler.hpp"
49 #include "runtime/frame.inline.hpp"
50 #include "runtime/init.hpp"
51 #include "runtime/interfaceSupport.hpp"
52 #include "runtime/java.hpp"
53 #include "runtime/javaCalls.hpp"
54 #include "runtime/jniPeriodicChecker.hpp"
55 #include "runtime/memprofiler.hpp"
56 #include "runtime/mutexLocker.hpp"
57 #include "runtime/objectMonitor.hpp"
58 #include "runtime/osThread.hpp"
59 #include "runtime/safepoint.hpp"
60 #include "runtime/sharedRuntime.hpp"
61 #include "runtime/statSampler.hpp"
62 #include "runtime/stubRoutines.hpp"
63 #include "runtime/task.hpp"
64 #include "runtime/threadCritical.hpp"
65 #include "runtime/threadLocalStorage.hpp"
66 #include "runtime/vframe.hpp"
67 #include "runtime/vframeArray.hpp"
68 #include "runtime/vframe_hp.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "runtime/vm_operations.hpp"
71 #include "services/attachListener.hpp"
72 #include "services/management.hpp"
73 #include "services/threadService.hpp"
74 #include "utilities/defaultStream.hpp"
75 #include "utilities/dtrace.hpp"
76 #include "utilities/events.hpp"
77 #include "utilities/preserveException.hpp"
78 #ifdef TARGET_OS_FAMILY_linux
79 # include "os_linux.inline.hpp"
80 # include "thread_linux.inline.hpp"
81 #endif
82 #ifdef TARGET_OS_FAMILY_solaris
83 # include "os_solaris.inline.hpp"
84 # include "thread_solaris.inline.hpp"
85 #endif
86 #ifdef TARGET_OS_FAMILY_windows
87 # include "os_windows.inline.hpp"
88 # include "thread_windows.inline.hpp"
89 #endif
90 #ifndef SERIALGC
91 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
92 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
93 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
94 #endif
95 #ifdef COMPILER1
96 #include "c1/c1_Compiler.hpp"
97 #endif
98 #ifdef COMPILER2
99 #include "opto/c2compiler.hpp"
100 #include "opto/idealGraphPrinter.hpp"
101 #endif
102
103 #ifdef DTRACE_ENABLED
104
105 // Only bother with this argument setup if dtrace is available
106
107 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
109 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
110 intptr_t, intptr_t, bool);
111 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
112 intptr_t, intptr_t, bool);
113
114 #define DTRACE_THREAD_PROBE(probe, javathread) \
115 { \
116 ResourceMark rm(this); \
117 int len = 0; \
118 const char* name = (javathread)->get_thread_name(); \
119 len = strlen(name); \
120 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
121 name, len, \
122 java_lang_Thread::thread_id((javathread)->threadObj()), \
123 (javathread)->osthread()->thread_id(), \
124 java_lang_Thread::is_daemon((javathread)->threadObj())); \
125 }
126
127 #else // ndef DTRACE_ENABLED
128
129 #define DTRACE_THREAD_PROBE(probe, javathread)
130
131 #endif // ndef DTRACE_ENABLED
132
133 // Class hierarchy
134 // - Thread
135 // - VMThread
136 // - WatcherThread
137 // - ConcurrentMarkSweepThread
138 // - JavaThread
139 // - CompilerThread
140
141 // ======= Thread ========
142
143 // Support for forcing alignment of thread objects for biased locking
144 void* Thread::operator new(size_t size) {
145 if (UseBiasedLocking) {
146 const int alignment = markOopDesc::biased_lock_alignment;
147 size_t aligned_size = size + (alignment - sizeof(intptr_t));
148 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
149 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
150 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
151 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
152 "JavaThread alignment code overflowed allocated storage");
153 if (TraceBiasedLocking) {
154 if (aligned_addr != real_malloc_addr)
155 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
156 real_malloc_addr, aligned_addr);
157 }
158 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
159 return aligned_addr;
160 } else {
161 return CHeapObj::operator new(size);
162 }
163 }
164
165 void Thread::operator delete(void* p) {
166 if (UseBiasedLocking) {
167 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
168 CHeapObj::operator delete(real_malloc_addr);
169 } else {
170 CHeapObj::operator delete(p);
171 }
172 }
173
174
175 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
176 // JavaThread
177
178
179 Thread::Thread() {
180 // stack
181 _stack_base = NULL;
182 _stack_size = 0;
183 _self_raw_id = 0;
184 _lgrp_id = -1;
185 _osthread = NULL;
186
187 // allocated data structures
188 set_resource_area(new ResourceArea());
189 set_handle_area(new HandleArea(NULL));
190 set_active_handles(NULL);
191 set_free_handle_block(NULL);
192 set_last_handle_mark(NULL);
193 set_osthread(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 _vm_operation_started_count = 0;
209 _vm_operation_completed_count = 0;
210 _current_pending_monitor = NULL;
211 _current_pending_monitor_is_from_java = true;
212 _current_waiting_monitor = NULL;
213 _num_nested_signal = 0;
214 omFreeList = NULL ;
215 omFreeCount = 0 ;
216 omFreeProvision = 32 ;
217 omInUseList = NULL ;
218 omInUseCount = 0 ;
219
220 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
221 _suspend_flags = 0;
222
223 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
224 _hashStateX = os::random() ;
225 _hashStateY = 842502087 ;
226 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
227 _hashStateW = 273326509 ;
228
229 _OnTrap = 0 ;
230 _schedctl = NULL ;
231 _Stalled = 0 ;
232 _TypeTag = 0x2BAD ;
233
234 // Many of the following fields are effectively final - immutable
235 // Note that nascent threads can't use the Native Monitor-Mutex
236 // construct until the _MutexEvent is initialized ...
237 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
238 // we might instead use a stack of ParkEvents that we could provision on-demand.
239 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
240 // and ::Release()
241 _ParkEvent = ParkEvent::Allocate (this) ;
242 _SleepEvent = ParkEvent::Allocate (this) ;
243 _MutexEvent = ParkEvent::Allocate (this) ;
244 _MuxEvent = ParkEvent::Allocate (this) ;
245
246 #ifdef CHECK_UNHANDLED_OOPS
247 if (CheckUnhandledOops) {
248 _unhandled_oops = new UnhandledOops(this);
249 }
250 #endif // CHECK_UNHANDLED_OOPS
251 #ifdef ASSERT
252 if (UseBiasedLocking) {
253 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
254 assert(this == _real_malloc_address ||
255 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
256 "bug in forced alignment of thread objects");
257 }
258 #endif /* ASSERT */
259 }
260
261 void Thread::initialize_thread_local_storage() {
262 // Note: Make sure this method only calls
263 // non-blocking operations. Otherwise, it might not work
264 // with the thread-startup/safepoint interaction.
265
266 // During Java thread startup, safepoint code should allow this
267 // method to complete because it may need to allocate memory to
268 // store information for the new thread.
269
270 // initialize structure dependent on thread local storage
271 ThreadLocalStorage::set_thread(this);
272
273 // set up any platform-specific state.
274 os::initialize_thread();
275
276 }
277
278 void Thread::record_stack_base_and_size() {
279 set_stack_base(os::current_stack_base());
280 set_stack_size(os::current_stack_size());
281 }
282
283
284 Thread::~Thread() {
285 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
286 ObjectSynchronizer::omFlush (this) ;
287
288 // deallocate data structures
289 delete resource_area();
290 // since the handle marks are using the handle area, we have to deallocated the root
291 // handle mark before deallocating the thread's handle area,
292 assert(last_handle_mark() != NULL, "check we have an element");
293 delete last_handle_mark();
294 assert(last_handle_mark() == NULL, "check we have reached the end");
295
296 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
297 // We NULL out the fields for good hygiene.
298 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
299 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
300 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
301 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
302
303 delete handle_area();
304
305 // osthread() can be NULL, if creation of thread failed.
306 if (osthread() != NULL) os::free_thread(osthread());
307
308 delete _SR_lock;
309
310 // clear thread local storage if the Thread is deleting itself
311 if (this == Thread::current()) {
312 ThreadLocalStorage::set_thread(NULL);
313 } else {
314 // In the case where we're not the current thread, invalidate all the
315 // caches in case some code tries to get the current thread or the
316 // thread that was destroyed, and gets stale information.
317 ThreadLocalStorage::invalidate_all();
318 }
319 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
320 }
321
322 // NOTE: dummy function for assertion purpose.
323 void Thread::run() {
324 ShouldNotReachHere();
325 }
326
327 #ifdef ASSERT
328 // Private method to check for dangling thread pointer
329 void check_for_dangling_thread_pointer(Thread *thread) {
330 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
331 "possibility of dangling Thread pointer");
332 }
333 #endif
334
335
336 #ifndef PRODUCT
337 // Tracing method for basic thread operations
338 void Thread::trace(const char* msg, const Thread* const thread) {
339 if (!TraceThreadEvents) return;
340 ResourceMark rm;
341 ThreadCritical tc;
342 const char *name = "non-Java thread";
343 int prio = -1;
344 if (thread->is_Java_thread()
345 && !thread->is_Compiler_thread()) {
346 // The Threads_lock must be held to get information about
347 // this thread but may not be in some situations when
348 // tracing thread events.
349 bool release_Threads_lock = false;
350 if (!Threads_lock->owned_by_self()) {
351 Threads_lock->lock();
352 release_Threads_lock = true;
353 }
354 JavaThread* jt = (JavaThread *)thread;
355 name = (char *)jt->get_thread_name();
356 oop thread_oop = jt->threadObj();
357 if (thread_oop != NULL) {
358 prio = java_lang_Thread::priority(thread_oop);
359 }
360 if (release_Threads_lock) {
361 Threads_lock->unlock();
362 }
363 }
364 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
365 }
366 #endif
367
368
369 ThreadPriority Thread::get_priority(const Thread* const thread) {
370 trace("get priority", thread);
371 ThreadPriority priority;
372 // Can return an error!
373 (void)os::get_priority(thread, priority);
374 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
375 return priority;
376 }
377
378 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
379 trace("set priority", thread);
380 debug_only(check_for_dangling_thread_pointer(thread);)
381 // Can return an error!
382 (void)os::set_priority(thread, priority);
383 }
384
385
386 void Thread::start(Thread* thread) {
387 trace("start", thread);
388 // Start is different from resume in that its safety is guaranteed by context or
389 // being called from a Java method synchronized on the Thread object.
390 if (!DisableStartThread) {
391 if (thread->is_Java_thread()) {
392 // Initialize the thread state to RUNNABLE before starting this thread.
393 // Can not set it after the thread started because we do not know the
394 // exact thread state at that time. It could be in MONITOR_WAIT or
395 // in SLEEPING or some other state.
396 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
397 java_lang_Thread::RUNNABLE);
398 }
399 os::start_thread(thread);
400 }
401 }
402
403 // Enqueue a VM_Operation to do the job for us - sometime later
404 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
405 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
406 VMThread::execute(vm_stop);
407 }
408
409
410 //
411 // Check if an external suspend request has completed (or has been
412 // cancelled). Returns true if the thread is externally suspended and
413 // false otherwise.
414 //
415 // The bits parameter returns information about the code path through
416 // the routine. Useful for debugging:
417 //
418 // set in is_ext_suspend_completed():
419 // 0x00000001 - routine was entered
420 // 0x00000010 - routine return false at end
421 // 0x00000100 - thread exited (return false)
422 // 0x00000200 - suspend request cancelled (return false)
423 // 0x00000400 - thread suspended (return true)
424 // 0x00001000 - thread is in a suspend equivalent state (return true)
425 // 0x00002000 - thread is native and walkable (return true)
426 // 0x00004000 - thread is native_trans and walkable (needed retry)
427 //
428 // set in wait_for_ext_suspend_completion():
429 // 0x00010000 - routine was entered
430 // 0x00020000 - suspend request cancelled before loop (return false)
431 // 0x00040000 - thread suspended before loop (return true)
432 // 0x00080000 - suspend request cancelled in loop (return false)
433 // 0x00100000 - thread suspended in loop (return true)
434 // 0x00200000 - suspend not completed during retry loop (return false)
435 //
436
437 // Helper class for tracing suspend wait debug bits.
438 //
439 // 0x00000100 indicates that the target thread exited before it could
440 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
441 // 0x00080000 each indicate a cancelled suspend request so they don't
442 // count as wait failures either.
443 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
444
445 class TraceSuspendDebugBits : public StackObj {
446 private:
447 JavaThread * jt;
448 bool is_wait;
449 bool called_by_wait; // meaningful when !is_wait
450 uint32_t * bits;
451
452 public:
453 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
454 uint32_t *_bits) {
455 jt = _jt;
456 is_wait = _is_wait;
457 called_by_wait = _called_by_wait;
458 bits = _bits;
459 }
460
461 ~TraceSuspendDebugBits() {
462 if (!is_wait) {
463 #if 1
464 // By default, don't trace bits for is_ext_suspend_completed() calls.
465 // That trace is very chatty.
466 return;
467 #else
468 if (!called_by_wait) {
469 // If tracing for is_ext_suspend_completed() is enabled, then only
470 // trace calls to it from wait_for_ext_suspend_completion()
471 return;
472 }
473 #endif
474 }
475
476 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
477 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
478 MutexLocker ml(Threads_lock); // needed for get_thread_name()
479 ResourceMark rm;
480
481 tty->print_cr(
482 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
483 jt->get_thread_name(), *bits);
484
485 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
486 }
487 }
488 }
489 };
490 #undef DEBUG_FALSE_BITS
491
492
493 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
494 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
495
496 bool did_trans_retry = false; // only do thread_in_native_trans retry once
497 bool do_trans_retry; // flag to force the retry
498
499 *bits |= 0x00000001;
500
501 do {
502 do_trans_retry = false;
503
504 if (is_exiting()) {
505 // Thread is in the process of exiting. This is always checked
506 // first to reduce the risk of dereferencing a freed JavaThread.
507 *bits |= 0x00000100;
508 return false;
509 }
510
511 if (!is_external_suspend()) {
512 // Suspend request is cancelled. This is always checked before
513 // is_ext_suspended() to reduce the risk of a rogue resume
514 // confusing the thread that made the suspend request.
515 *bits |= 0x00000200;
516 return false;
517 }
518
519 if (is_ext_suspended()) {
520 // thread is suspended
521 *bits |= 0x00000400;
522 return true;
523 }
524
525 // Now that we no longer do hard suspends of threads running
526 // native code, the target thread can be changing thread state
527 // while we are in this routine:
528 //
529 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
530 //
531 // We save a copy of the thread state as observed at this moment
532 // and make our decision about suspend completeness based on the
533 // copy. This closes the race where the thread state is seen as
534 // _thread_in_native_trans in the if-thread_blocked check, but is
535 // seen as _thread_blocked in if-thread_in_native_trans check.
536 JavaThreadState save_state = thread_state();
537
538 if (save_state == _thread_blocked && is_suspend_equivalent()) {
539 // If the thread's state is _thread_blocked and this blocking
540 // condition is known to be equivalent to a suspend, then we can
541 // consider the thread to be externally suspended. This means that
542 // the code that sets _thread_blocked has been modified to do
543 // self-suspension if the blocking condition releases. We also
544 // used to check for CONDVAR_WAIT here, but that is now covered by
545 // the _thread_blocked with self-suspension check.
546 //
547 // Return true since we wouldn't be here unless there was still an
548 // external suspend request.
549 *bits |= 0x00001000;
550 return true;
551 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
552 // Threads running native code will self-suspend on native==>VM/Java
553 // transitions. If its stack is walkable (should always be the case
554 // unless this function is called before the actual java_suspend()
555 // call), then the wait is done.
556 *bits |= 0x00002000;
557 return true;
558 } else if (!called_by_wait && !did_trans_retry &&
559 save_state == _thread_in_native_trans &&
560 frame_anchor()->walkable()) {
561 // The thread is transitioning from thread_in_native to another
562 // thread state. check_safepoint_and_suspend_for_native_trans()
563 // will force the thread to self-suspend. If it hasn't gotten
564 // there yet we may have caught the thread in-between the native
565 // code check above and the self-suspend. Lucky us. If we were
566 // called by wait_for_ext_suspend_completion(), then it
567 // will be doing the retries so we don't have to.
568 //
569 // Since we use the saved thread state in the if-statement above,
570 // there is a chance that the thread has already transitioned to
571 // _thread_blocked by the time we get here. In that case, we will
572 // make a single unnecessary pass through the logic below. This
573 // doesn't hurt anything since we still do the trans retry.
574
575 *bits |= 0x00004000;
576
577 // Once the thread leaves thread_in_native_trans for another
578 // thread state, we break out of this retry loop. We shouldn't
579 // need this flag to prevent us from getting back here, but
580 // sometimes paranoia is good.
581 did_trans_retry = true;
582
583 // We wait for the thread to transition to a more usable state.
584 for (int i = 1; i <= SuspendRetryCount; i++) {
585 // We used to do an "os::yield_all(i)" call here with the intention
586 // that yielding would increase on each retry. However, the parameter
587 // is ignored on Linux which means the yield didn't scale up. Waiting
588 // on the SR_lock below provides a much more predictable scale up for
589 // the delay. It also provides a simple/direct point to check for any
590 // safepoint requests from the VMThread
591
592 // temporarily drops SR_lock while doing wait with safepoint check
593 // (if we're a JavaThread - the WatcherThread can also call this)
594 // and increase delay with each retry
595 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
596
597 // check the actual thread state instead of what we saved above
598 if (thread_state() != _thread_in_native_trans) {
599 // the thread has transitioned to another thread state so
600 // try all the checks (except this one) one more time.
601 do_trans_retry = true;
602 break;
603 }
604 } // end retry loop
605
606
607 }
608 } while (do_trans_retry);
609
610 *bits |= 0x00000010;
611 return false;
612 }
613
614 //
615 // Wait for an external suspend request to complete (or be cancelled).
616 // Returns true if the thread is externally suspended and false otherwise.
617 //
618 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
619 uint32_t *bits) {
620 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
621 false /* !called_by_wait */, bits);
622
623 // local flag copies to minimize SR_lock hold time
624 bool is_suspended;
625 bool pending;
626 uint32_t reset_bits;
627
628 // set a marker so is_ext_suspend_completed() knows we are the caller
629 *bits |= 0x00010000;
630
631 // We use reset_bits to reinitialize the bits value at the top of
632 // each retry loop. This allows the caller to make use of any
633 // unused bits for their own marking purposes.
634 reset_bits = *bits;
635
636 {
637 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
638 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
639 delay, bits);
640 pending = is_external_suspend();
641 }
642 // must release SR_lock to allow suspension to complete
643
644 if (!pending) {
645 // A cancelled suspend request is the only false return from
646 // is_ext_suspend_completed() that keeps us from entering the
647 // retry loop.
648 *bits |= 0x00020000;
649 return false;
650 }
651
652 if (is_suspended) {
653 *bits |= 0x00040000;
654 return true;
655 }
656
657 for (int i = 1; i <= retries; i++) {
658 *bits = reset_bits; // reinit to only track last retry
659
660 // We used to do an "os::yield_all(i)" call here with the intention
661 // that yielding would increase on each retry. However, the parameter
662 // is ignored on Linux which means the yield didn't scale up. Waiting
663 // on the SR_lock below provides a much more predictable scale up for
664 // the delay. It also provides a simple/direct point to check for any
665 // safepoint requests from the VMThread
666
667 {
668 MutexLocker ml(SR_lock());
669 // wait with safepoint check (if we're a JavaThread - the WatcherThread
670 // can also call this) and increase delay with each retry
671 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
672
673 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
674 delay, bits);
675
676 // It is possible for the external suspend request to be cancelled
677 // (by a resume) before the actual suspend operation is completed.
678 // Refresh our local copy to see if we still need to wait.
679 pending = is_external_suspend();
680 }
681
682 if (!pending) {
683 // A cancelled suspend request is the only false return from
684 // is_ext_suspend_completed() that keeps us from staying in the
685 // retry loop.
686 *bits |= 0x00080000;
687 return false;
688 }
689
690 if (is_suspended) {
691 *bits |= 0x00100000;
692 return true;
693 }
694 } // end retry loop
695
696 // thread did not suspend after all our retries
697 *bits |= 0x00200000;
698 return false;
699 }
700
701 #ifndef PRODUCT
702 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
703
704 // This should not need to be atomic as the only way for simultaneous
705 // updates is via interrupts. Even then this should be rare or non-existant
706 // and we don't care that much anyway.
707
708 int index = _jmp_ring_index;
709 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
710 _jmp_ring[index]._target = (intptr_t) target;
711 _jmp_ring[index]._instruction = (intptr_t) instr;
712 _jmp_ring[index]._file = file;
713 _jmp_ring[index]._line = line;
714 }
715 #endif /* PRODUCT */
716
717 // Called by flat profiler
718 // Callers have already called wait_for_ext_suspend_completion
719 // The assertion for that is currently too complex to put here:
720 bool JavaThread::profile_last_Java_frame(frame* _fr) {
721 bool gotframe = false;
722 // self suspension saves needed state.
723 if (has_last_Java_frame() && _anchor.walkable()) {
724 *_fr = pd_last_frame();
725 gotframe = true;
726 }
727 return gotframe;
728 }
729
730 void Thread::interrupt(Thread* thread) {
731 trace("interrupt", thread);
732 debug_only(check_for_dangling_thread_pointer(thread);)
733 os::interrupt(thread);
734 }
735
736 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
737 trace("is_interrupted", thread);
738 debug_only(check_for_dangling_thread_pointer(thread);)
739 // Note: If clear_interrupted==false, this simply fetches and
740 // returns the value of the field osthread()->interrupted().
741 return os::is_interrupted(thread, clear_interrupted);
742 }
743
744
745 // GC Support
746 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
747 jint thread_parity = _oops_do_parity;
748 if (thread_parity != strong_roots_parity) {
749 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
750 if (res == thread_parity) return true;
751 else {
752 guarantee(res == strong_roots_parity, "Or else what?");
753 assert(SharedHeap::heap()->n_par_threads() > 0,
754 "Should only fail when parallel.");
755 return false;
756 }
757 }
758 assert(SharedHeap::heap()->n_par_threads() > 0,
759 "Should only fail when parallel.");
760 return false;
761 }
762
763 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
764 active_handles()->oops_do(f);
765 // Do oop for ThreadShadow
766 f->do_oop((oop*)&_pending_exception);
767 handle_area()->oops_do(f);
768 }
769
770 void Thread::nmethods_do(CodeBlobClosure* cf) {
771 // no nmethods in a generic thread...
772 }
773
774 void Thread::print_on(outputStream* st) const {
775 // get_priority assumes osthread initialized
776 if (osthread() != NULL) {
777 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
778 osthread()->print_on(st);
779 }
780 debug_only(if (WizardMode) print_owned_locks_on(st);)
781 }
782
783 // Thread::print_on_error() is called by fatal error handler. Don't use
784 // any lock or allocate memory.
785 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
786 if (is_VM_thread()) st->print("VMThread");
787 else if (is_Compiler_thread()) st->print("CompilerThread");
788 else if (is_Java_thread()) st->print("JavaThread");
789 else if (is_GC_task_thread()) st->print("GCTaskThread");
790 else if (is_Watcher_thread()) st->print("WatcherThread");
791 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
792 else st->print("Thread");
793
794 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
795 _stack_base - _stack_size, _stack_base);
796
797 if (osthread()) {
798 st->print(" [id=%d]", osthread()->thread_id());
799 }
800 }
801
802 #ifdef ASSERT
803 void Thread::print_owned_locks_on(outputStream* st) const {
804 Monitor *cur = _owned_locks;
805 if (cur == NULL) {
806 st->print(" (no locks) ");
807 } else {
808 st->print_cr(" Locks owned:");
809 while(cur) {
810 cur->print_on(st);
811 cur = cur->next();
812 }
813 }
814 }
815
816 static int ref_use_count = 0;
817
818 bool Thread::owns_locks_but_compiled_lock() const {
819 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
820 if (cur != Compile_lock) return true;
821 }
822 return false;
823 }
824
825
826 #endif
827
828 #ifndef PRODUCT
829
830 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
831 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
832 // no threads which allow_vm_block's are held
833 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
834 // Check if current thread is allowed to block at a safepoint
835 if (!(_allow_safepoint_count == 0))
836 fatal("Possible safepoint reached by thread that does not allow it");
837 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
838 fatal("LEAF method calling lock?");
839 }
840
841 #ifdef ASSERT
842 if (potential_vm_operation && is_Java_thread()
843 && !Universe::is_bootstrapping()) {
844 // Make sure we do not hold any locks that the VM thread also uses.
845 // This could potentially lead to deadlocks
846 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
847 // Threads_lock is special, since the safepoint synchronization will not start before this is
848 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
849 // since it is used to transfer control between JavaThreads and the VMThread
850 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
851 if ( (cur->allow_vm_block() &&
852 cur != Threads_lock &&
853 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
854 cur != VMOperationRequest_lock &&
855 cur != VMOperationQueue_lock) ||
856 cur->rank() == Mutex::special) {
857 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
858 }
859 }
860 }
861
862 if (GCALotAtAllSafepoints) {
863 // We could enter a safepoint here and thus have a gc
864 InterfaceSupport::check_gc_alot();
865 }
866 #endif
867 }
868 #endif
869
870 bool Thread::is_in_stack(address adr) const {
871 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
872 address end = os::current_stack_pointer();
873 if (stack_base() >= adr && adr >= end) return true;
874
875 return false;
876 }
877
878
879 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
880 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
881 // used for compilation in the future. If that change is made, the need for these methods
882 // should be revisited, and they should be removed if possible.
883
884 bool Thread::is_lock_owned(address adr) const {
885 return on_local_stack(adr);
886 }
887
888 bool Thread::set_as_starting_thread() {
889 // NOTE: this must be called inside the main thread.
890 return os::create_main_thread((JavaThread*)this);
891 }
892
893 static void initialize_class(symbolHandle class_name, TRAPS) {
894 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
895 instanceKlass::cast(klass)->initialize(CHECK);
896 }
897
898
899 // Creates the initial ThreadGroup
900 static Handle create_initial_thread_group(TRAPS) {
901 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_ThreadGroup(), true, CHECK_NH);
902 instanceKlassHandle klass (THREAD, k);
903
904 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
905 {
906 JavaValue result(T_VOID);
907 JavaCalls::call_special(&result,
908 system_instance,
909 klass,
910 vmSymbolHandles::object_initializer_name(),
911 vmSymbolHandles::void_method_signature(),
912 CHECK_NH);
913 }
914 Universe::set_system_thread_group(system_instance());
915
916 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
917 {
918 JavaValue result(T_VOID);
919 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
920 JavaCalls::call_special(&result,
921 main_instance,
922 klass,
923 vmSymbolHandles::object_initializer_name(),
924 vmSymbolHandles::threadgroup_string_void_signature(),
925 system_instance,
926 string,
927 CHECK_NH);
928 }
929 return main_instance;
930 }
931
932 // Creates the initial Thread
933 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
934 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK_NULL);
935 instanceKlassHandle klass (THREAD, k);
936 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
937
938 java_lang_Thread::set_thread(thread_oop(), thread);
939 java_lang_Thread::set_priority(thread_oop(), NormPriority);
940 thread->set_threadObj(thread_oop());
941
942 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
943
944 JavaValue result(T_VOID);
945 JavaCalls::call_special(&result, thread_oop,
946 klass,
947 vmSymbolHandles::object_initializer_name(),
948 vmSymbolHandles::threadgroup_string_void_signature(),
949 thread_group,
950 string,
951 CHECK_NULL);
952 return thread_oop();
953 }
954
955 static void call_initializeSystemClass(TRAPS) {
956 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
957 instanceKlassHandle klass (THREAD, k);
958
959 JavaValue result(T_VOID);
960 JavaCalls::call_static(&result, klass, vmSymbolHandles::initializeSystemClass_name(),
961 vmSymbolHandles::void_method_signature(), CHECK);
962 }
963
964 #ifdef KERNEL
965 static void set_jkernel_boot_classloader_hook(TRAPS) {
966 klassOop k = SystemDictionary::sun_jkernel_DownloadManager_klass();
967 instanceKlassHandle klass (THREAD, k);
968
969 if (k == NULL) {
970 // sun.jkernel.DownloadManager may not present in the JDK; just return
971 return;
972 }
973
974 JavaValue result(T_VOID);
975 JavaCalls::call_static(&result, klass, vmSymbolHandles::setBootClassLoaderHook_name(),
976 vmSymbolHandles::void_method_signature(), CHECK);
977 }
978 #endif // KERNEL
979
980 static void reset_vm_info_property(TRAPS) {
981 // the vm info string
982 ResourceMark rm(THREAD);
983 const char *vm_info = VM_Version::vm_info_string();
984
985 // java.lang.System class
986 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
987 instanceKlassHandle klass (THREAD, k);
988
989 // setProperty arguments
990 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
991 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
992
993 // return value
994 JavaValue r(T_OBJECT);
995
996 // public static String setProperty(String key, String value);
997 JavaCalls::call_static(&r,
998 klass,
999 vmSymbolHandles::setProperty_name(),
1000 vmSymbolHandles::string_string_string_signature(),
1001 key_str,
1002 value_str,
1003 CHECK);
1004 }
1005
1006
1007 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1008 assert(thread_group.not_null(), "thread group should be specified");
1009 assert(threadObj() == NULL, "should only create Java thread object once");
1010
1011 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK);
1012 instanceKlassHandle klass (THREAD, k);
1013 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1014
1015 java_lang_Thread::set_thread(thread_oop(), this);
1016 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1017 set_threadObj(thread_oop());
1018
1019 JavaValue result(T_VOID);
1020 if (thread_name != NULL) {
1021 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1022 // Thread gets assigned specified name and null target
1023 JavaCalls::call_special(&result,
1024 thread_oop,
1025 klass,
1026 vmSymbolHandles::object_initializer_name(),
1027 vmSymbolHandles::threadgroup_string_void_signature(),
1028 thread_group, // Argument 1
1029 name, // Argument 2
1030 THREAD);
1031 } else {
1032 // Thread gets assigned name "Thread-nnn" and null target
1033 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1034 JavaCalls::call_special(&result,
1035 thread_oop,
1036 klass,
1037 vmSymbolHandles::object_initializer_name(),
1038 vmSymbolHandles::threadgroup_runnable_void_signature(),
1039 thread_group, // Argument 1
1040 Handle(), // Argument 2
1041 THREAD);
1042 }
1043
1044
1045 if (daemon) {
1046 java_lang_Thread::set_daemon(thread_oop());
1047 }
1048
1049 if (HAS_PENDING_EXCEPTION) {
1050 return;
1051 }
1052
1053 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1054 Handle threadObj(this, this->threadObj());
1055
1056 JavaCalls::call_special(&result,
1057 thread_group,
1058 group,
1059 vmSymbolHandles::add_method_name(),
1060 vmSymbolHandles::thread_void_signature(),
1061 threadObj, // Arg 1
1062 THREAD);
1063
1064
1065 }
1066
1067 // NamedThread -- non-JavaThread subclasses with multiple
1068 // uniquely named instances should derive from this.
1069 NamedThread::NamedThread() : Thread() {
1070 _name = NULL;
1071 _processed_thread = NULL;
1072 }
1073
1074 NamedThread::~NamedThread() {
1075 if (_name != NULL) {
1076 FREE_C_HEAP_ARRAY(char, _name);
1077 _name = NULL;
1078 }
1079 }
1080
1081 void NamedThread::set_name(const char* format, ...) {
1082 guarantee(_name == NULL, "Only get to set name once.");
1083 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1084 guarantee(_name != NULL, "alloc failure");
1085 va_list ap;
1086 va_start(ap, format);
1087 jio_vsnprintf(_name, max_name_len, format, ap);
1088 va_end(ap);
1089 }
1090
1091 // ======= WatcherThread ========
1092
1093 // The watcher thread exists to simulate timer interrupts. It should
1094 // be replaced by an abstraction over whatever native support for
1095 // timer interrupts exists on the platform.
1096
1097 WatcherThread* WatcherThread::_watcher_thread = NULL;
1098 volatile bool WatcherThread::_should_terminate = false;
1099
1100 WatcherThread::WatcherThread() : Thread() {
1101 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1102 if (os::create_thread(this, os::watcher_thread)) {
1103 _watcher_thread = this;
1104
1105 // Set the watcher thread to the highest OS priority which should not be
1106 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1107 // is created. The only normal thread using this priority is the reference
1108 // handler thread, which runs for very short intervals only.
1109 // If the VMThread's priority is not lower than the WatcherThread profiling
1110 // will be inaccurate.
1111 os::set_priority(this, MaxPriority);
1112 if (!DisableStartThread) {
1113 os::start_thread(this);
1114 }
1115 }
1116 }
1117
1118 void WatcherThread::run() {
1119 assert(this == watcher_thread(), "just checking");
1120
1121 this->record_stack_base_and_size();
1122 this->initialize_thread_local_storage();
1123 this->set_active_handles(JNIHandleBlock::allocate_block());
1124 while(!_should_terminate) {
1125 assert(watcher_thread() == Thread::current(), "thread consistency check");
1126 assert(watcher_thread() == this, "thread consistency check");
1127
1128 // Calculate how long it'll be until the next PeriodicTask work
1129 // should be done, and sleep that amount of time.
1130 size_t time_to_wait = PeriodicTask::time_to_wait();
1131
1132 // we expect this to timeout - we only ever get unparked when
1133 // we should terminate
1134 {
1135 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1136
1137 jlong prev_time = os::javaTimeNanos();
1138 for (;;) {
1139 int res= _SleepEvent->park(time_to_wait);
1140 if (res == OS_TIMEOUT || _should_terminate)
1141 break;
1142 // spurious wakeup of some kind
1143 jlong now = os::javaTimeNanos();
1144 time_to_wait -= (now - prev_time) / 1000000;
1145 if (time_to_wait <= 0)
1146 break;
1147 prev_time = now;
1148 }
1149 }
1150
1151 if (is_error_reported()) {
1152 // A fatal error has happened, the error handler(VMError::report_and_die)
1153 // should abort JVM after creating an error log file. However in some
1154 // rare cases, the error handler itself might deadlock. Here we try to
1155 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1156 //
1157 // This code is in WatcherThread because WatcherThread wakes up
1158 // periodically so the fatal error handler doesn't need to do anything;
1159 // also because the WatcherThread is less likely to crash than other
1160 // threads.
1161
1162 for (;;) {
1163 if (!ShowMessageBoxOnError
1164 && (OnError == NULL || OnError[0] == '\0')
1165 && Arguments::abort_hook() == NULL) {
1166 os::sleep(this, 2 * 60 * 1000, false);
1167 fdStream err(defaultStream::output_fd());
1168 err.print_raw_cr("# [ timer expired, abort... ]");
1169 // skip atexit/vm_exit/vm_abort hooks
1170 os::die();
1171 }
1172
1173 // Wake up 5 seconds later, the fatal handler may reset OnError or
1174 // ShowMessageBoxOnError when it is ready to abort.
1175 os::sleep(this, 5 * 1000, false);
1176 }
1177 }
1178
1179 PeriodicTask::real_time_tick(time_to_wait);
1180
1181 // If we have no more tasks left due to dynamic disenrollment,
1182 // shut down the thread since we don't currently support dynamic enrollment
1183 if (PeriodicTask::num_tasks() == 0) {
1184 _should_terminate = true;
1185 }
1186 }
1187
1188 // Signal that it is terminated
1189 {
1190 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1191 _watcher_thread = NULL;
1192 Terminator_lock->notify();
1193 }
1194
1195 // Thread destructor usually does this..
1196 ThreadLocalStorage::set_thread(NULL);
1197 }
1198
1199 void WatcherThread::start() {
1200 if (watcher_thread() == NULL) {
1201 _should_terminate = false;
1202 // Create the single instance of WatcherThread
1203 new WatcherThread();
1204 }
1205 }
1206
1207 void WatcherThread::stop() {
1208 // it is ok to take late safepoints here, if needed
1209 MutexLocker mu(Terminator_lock);
1210 _should_terminate = true;
1211 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1212
1213 Thread* watcher = watcher_thread();
1214 if (watcher != NULL)
1215 watcher->_SleepEvent->unpark();
1216
1217 while(watcher_thread() != NULL) {
1218 // This wait should make safepoint checks, wait without a timeout,
1219 // and wait as a suspend-equivalent condition.
1220 //
1221 // Note: If the FlatProfiler is running, then this thread is waiting
1222 // for the WatcherThread to terminate and the WatcherThread, via the
1223 // FlatProfiler task, is waiting for the external suspend request on
1224 // this thread to complete. wait_for_ext_suspend_completion() will
1225 // eventually timeout, but that takes time. Making this wait a
1226 // suspend-equivalent condition solves that timeout problem.
1227 //
1228 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1229 Mutex::_as_suspend_equivalent_flag);
1230 }
1231 }
1232
1233 void WatcherThread::print_on(outputStream* st) const {
1234 st->print("\"%s\" ", name());
1235 Thread::print_on(st);
1236 st->cr();
1237 }
1238
1239 // ======= JavaThread ========
1240
1241 // A JavaThread is a normal Java thread
1242
1243 void JavaThread::initialize() {
1244 // Initialize fields
1245
1246 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1247 set_claimed_par_id(-1);
1248
1249 set_saved_exception_pc(NULL);
1250 set_threadObj(NULL);
1251 _anchor.clear();
1252 set_entry_point(NULL);
1253 set_jni_functions(jni_functions());
1254 set_callee_target(NULL);
1255 set_vm_result(NULL);
1256 set_vm_result_2(NULL);
1257 set_vframe_array_head(NULL);
1258 set_vframe_array_last(NULL);
1259 set_deferred_locals(NULL);
1260 set_deopt_mark(NULL);
1261 set_deopt_nmethod(NULL);
1262 clear_must_deopt_id();
1263 set_monitor_chunks(NULL);
1264 set_next(NULL);
1265 set_thread_state(_thread_new);
1266 _terminated = _not_terminated;
1267 _privileged_stack_top = NULL;
1268 _array_for_gc = NULL;
1269 _suspend_equivalent = false;
1270 _in_deopt_handler = 0;
1271 _doing_unsafe_access = false;
1272 _stack_guard_state = stack_guard_unused;
1273 _exception_oop = NULL;
1274 _exception_pc = 0;
1275 _exception_handler_pc = 0;
1276 _exception_stack_size = 0;
1277 _is_method_handle_return = 0;
1278 _jvmti_thread_state= NULL;
1279 _should_post_on_exceptions_flag = JNI_FALSE;
1280 _jvmti_get_loaded_classes_closure = NULL;
1281 _interp_only_mode = 0;
1282 _special_runtime_exit_condition = _no_async_condition;
1283 _pending_async_exception = NULL;
1284 _is_compiling = false;
1285 _thread_stat = NULL;
1286 _thread_stat = new ThreadStatistics();
1287 _blocked_on_compilation = false;
1288 _jni_active_critical = 0;
1289 _do_not_unlock_if_synchronized = false;
1290 _cached_monitor_info = NULL;
1291 _parker = Parker::Allocate(this) ;
1292
1293 #ifndef PRODUCT
1294 _jmp_ring_index = 0;
1295 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1296 record_jump(NULL, NULL, NULL, 0);
1297 }
1298 #endif /* PRODUCT */
1299
1300 set_thread_profiler(NULL);
1301 if (FlatProfiler::is_active()) {
1302 // This is where we would decide to either give each thread it's own profiler
1303 // or use one global one from FlatProfiler,
1304 // or up to some count of the number of profiled threads, etc.
1305 ThreadProfiler* pp = new ThreadProfiler();
1306 pp->engage();
1307 set_thread_profiler(pp);
1308 }
1309
1310 // Setup safepoint state info for this thread
1311 ThreadSafepointState::create(this);
1312
1313 debug_only(_java_call_counter = 0);
1314
1315 // JVMTI PopFrame support
1316 _popframe_condition = popframe_inactive;
1317 _popframe_preserved_args = NULL;
1318 _popframe_preserved_args_size = 0;
1319
1320 pd_initialize();
1321 }
1322
1323 #ifndef SERIALGC
1324 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1325 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1326 #endif // !SERIALGC
1327
1328 JavaThread::JavaThread(bool is_attaching) :
1329 Thread()
1330 #ifndef SERIALGC
1331 , _satb_mark_queue(&_satb_mark_queue_set),
1332 _dirty_card_queue(&_dirty_card_queue_set)
1333 #endif // !SERIALGC
1334 {
1335 initialize();
1336 _is_attaching = is_attaching;
1337 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1338 }
1339
1340 bool JavaThread::reguard_stack(address cur_sp) {
1341 if (_stack_guard_state != stack_guard_yellow_disabled) {
1342 return true; // Stack already guarded or guard pages not needed.
1343 }
1344
1345 if (register_stack_overflow()) {
1346 // For those architectures which have separate register and
1347 // memory stacks, we must check the register stack to see if
1348 // it has overflowed.
1349 return false;
1350 }
1351
1352 // Java code never executes within the yellow zone: the latter is only
1353 // there to provoke an exception during stack banging. If java code
1354 // is executing there, either StackShadowPages should be larger, or
1355 // some exception code in c1, c2 or the interpreter isn't unwinding
1356 // when it should.
1357 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1358
1359 enable_stack_yellow_zone();
1360 return true;
1361 }
1362
1363 bool JavaThread::reguard_stack(void) {
1364 return reguard_stack(os::current_stack_pointer());
1365 }
1366
1367
1368 void JavaThread::block_if_vm_exited() {
1369 if (_terminated == _vm_exited) {
1370 // _vm_exited is set at safepoint, and Threads_lock is never released
1371 // we will block here forever
1372 Threads_lock->lock_without_safepoint_check();
1373 ShouldNotReachHere();
1374 }
1375 }
1376
1377
1378 // Remove this ifdef when C1 is ported to the compiler interface.
1379 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1380
1381 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1382 Thread()
1383 #ifndef SERIALGC
1384 , _satb_mark_queue(&_satb_mark_queue_set),
1385 _dirty_card_queue(&_dirty_card_queue_set)
1386 #endif // !SERIALGC
1387 {
1388 if (TraceThreadEvents) {
1389 tty->print_cr("creating thread %p", this);
1390 }
1391 initialize();
1392 _is_attaching = false;
1393 set_entry_point(entry_point);
1394 // Create the native thread itself.
1395 // %note runtime_23
1396 os::ThreadType thr_type = os::java_thread;
1397 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1398 os::java_thread;
1399 os::create_thread(this, thr_type, stack_sz);
1400
1401 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1402 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1403 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1404 // the exception consists of creating the exception object & initializing it, initialization
1405 // will leave the VM via a JavaCall and then all locks must be unlocked).
1406 //
1407 // The thread is still suspended when we reach here. Thread must be explicit started
1408 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1409 // by calling Threads:add. The reason why this is not done here, is because the thread
1410 // object must be fully initialized (take a look at JVM_Start)
1411 }
1412
1413 JavaThread::~JavaThread() {
1414 if (TraceThreadEvents) {
1415 tty->print_cr("terminate thread %p", this);
1416 }
1417
1418 // JSR166 -- return the parker to the free list
1419 Parker::Release(_parker);
1420 _parker = NULL ;
1421
1422 // Free any remaining previous UnrollBlock
1423 vframeArray* old_array = vframe_array_last();
1424
1425 if (old_array != NULL) {
1426 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1427 old_array->set_unroll_block(NULL);
1428 delete old_info;
1429 delete old_array;
1430 }
1431
1432 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1433 if (deferred != NULL) {
1434 // This can only happen if thread is destroyed before deoptimization occurs.
1435 assert(deferred->length() != 0, "empty array!");
1436 do {
1437 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1438 deferred->remove_at(0);
1439 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1440 delete dlv;
1441 } while (deferred->length() != 0);
1442 delete deferred;
1443 }
1444
1445 // All Java related clean up happens in exit
1446 ThreadSafepointState::destroy(this);
1447 if (_thread_profiler != NULL) delete _thread_profiler;
1448 if (_thread_stat != NULL) delete _thread_stat;
1449 }
1450
1451
1452 // The first routine called by a new Java thread
1453 void JavaThread::run() {
1454 // initialize thread-local alloc buffer related fields
1455 this->initialize_tlab();
1456
1457 // used to test validitity of stack trace backs
1458 this->record_base_of_stack_pointer();
1459
1460 // Record real stack base and size.
1461 this->record_stack_base_and_size();
1462
1463 // Initialize thread local storage; set before calling MutexLocker
1464 this->initialize_thread_local_storage();
1465
1466 this->create_stack_guard_pages();
1467
1468 this->cache_global_variables();
1469
1470 // Thread is now sufficient initialized to be handled by the safepoint code as being
1471 // in the VM. Change thread state from _thread_new to _thread_in_vm
1472 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1473
1474 assert(JavaThread::current() == this, "sanity check");
1475 assert(!Thread::current()->owns_locks(), "sanity check");
1476
1477 DTRACE_THREAD_PROBE(start, this);
1478
1479 // This operation might block. We call that after all safepoint checks for a new thread has
1480 // been completed.
1481 this->set_active_handles(JNIHandleBlock::allocate_block());
1482
1483 if (JvmtiExport::should_post_thread_life()) {
1484 JvmtiExport::post_thread_start(this);
1485 }
1486
1487 // We call another function to do the rest so we are sure that the stack addresses used
1488 // from there will be lower than the stack base just computed
1489 thread_main_inner();
1490
1491 // Note, thread is no longer valid at this point!
1492 }
1493
1494
1495 void JavaThread::thread_main_inner() {
1496 assert(JavaThread::current() == this, "sanity check");
1497 assert(this->threadObj() != NULL, "just checking");
1498
1499 // Execute thread entry point. If this thread is being asked to restart,
1500 // or has been stopped before starting, do not reexecute entry point.
1501 // Note: Due to JVM_StopThread we can have pending exceptions already!
1502 if (!this->has_pending_exception() && !java_lang_Thread::is_stillborn(this->threadObj())) {
1503 // enter the thread's entry point only if we have no pending exceptions
1504 HandleMark hm(this);
1505 this->entry_point()(this, this);
1506 }
1507
1508 DTRACE_THREAD_PROBE(stop, this);
1509
1510 this->exit(false);
1511 delete this;
1512 }
1513
1514
1515 static void ensure_join(JavaThread* thread) {
1516 // We do not need to grap the Threads_lock, since we are operating on ourself.
1517 Handle threadObj(thread, thread->threadObj());
1518 assert(threadObj.not_null(), "java thread object must exist");
1519 ObjectLocker lock(threadObj, thread);
1520 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1521 thread->clear_pending_exception();
1522 // It is of profound importance that we set the stillborn bit and reset the thread object,
1523 // before we do the notify. Since, changing these two variable will make JVM_IsAlive return
1524 // false. So in case another thread is doing a join on this thread , it will detect that the thread
1525 // is dead when it gets notified.
1526 java_lang_Thread::set_stillborn(threadObj());
1527 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1528 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1529 java_lang_Thread::set_thread(threadObj(), NULL);
1530 lock.notify_all(thread);
1531 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1532 thread->clear_pending_exception();
1533 }
1534
1535
1536 // For any new cleanup additions, please check to see if they need to be applied to
1537 // cleanup_failed_attach_current_thread as well.
1538 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1539 assert(this == JavaThread::current(), "thread consistency check");
1540 if (!InitializeJavaLangSystem) return;
1541
1542 HandleMark hm(this);
1543 Handle uncaught_exception(this, this->pending_exception());
1544 this->clear_pending_exception();
1545 Handle threadObj(this, this->threadObj());
1546 assert(threadObj.not_null(), "Java thread object should be created");
1547
1548 if (get_thread_profiler() != NULL) {
1549 get_thread_profiler()->disengage();
1550 ResourceMark rm;
1551 get_thread_profiler()->print(get_thread_name());
1552 }
1553
1554
1555 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1556 {
1557 EXCEPTION_MARK;
1558
1559 CLEAR_PENDING_EXCEPTION;
1560 }
1561 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1562 // has to be fixed by a runtime query method
1563 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1564 // JSR-166: change call from from ThreadGroup.uncaughtException to
1565 // java.lang.Thread.dispatchUncaughtException
1566 if (uncaught_exception.not_null()) {
1567 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1568 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1569 (address)uncaught_exception(), (address)threadObj(), (address)group());
1570 {
1571 EXCEPTION_MARK;
1572 // Check if the method Thread.dispatchUncaughtException() exists. If so
1573 // call it. Otherwise we have an older library without the JSR-166 changes,
1574 // so call ThreadGroup.uncaughtException()
1575 KlassHandle recvrKlass(THREAD, threadObj->klass());
1576 CallInfo callinfo;
1577 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1578 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1579 vmSymbolHandles::dispatchUncaughtException_name(),
1580 vmSymbolHandles::throwable_void_signature(),
1581 KlassHandle(), false, false, THREAD);
1582 CLEAR_PENDING_EXCEPTION;
1583 methodHandle method = callinfo.selected_method();
1584 if (method.not_null()) {
1585 JavaValue result(T_VOID);
1586 JavaCalls::call_virtual(&result,
1587 threadObj, thread_klass,
1588 vmSymbolHandles::dispatchUncaughtException_name(),
1589 vmSymbolHandles::throwable_void_signature(),
1590 uncaught_exception,
1591 THREAD);
1592 } else {
1593 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1594 JavaValue result(T_VOID);
1595 JavaCalls::call_virtual(&result,
1596 group, thread_group,
1597 vmSymbolHandles::uncaughtException_name(),
1598 vmSymbolHandles::thread_throwable_void_signature(),
1599 threadObj, // Arg 1
1600 uncaught_exception, // Arg 2
1601 THREAD);
1602 }
1603 CLEAR_PENDING_EXCEPTION;
1604 }
1605 }
1606
1607 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1608 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1609 // is deprecated anyhow.
1610 { int count = 3;
1611 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1612 EXCEPTION_MARK;
1613 JavaValue result(T_VOID);
1614 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1615 JavaCalls::call_virtual(&result,
1616 threadObj, thread_klass,
1617 vmSymbolHandles::exit_method_name(),
1618 vmSymbolHandles::void_method_signature(),
1619 THREAD);
1620 CLEAR_PENDING_EXCEPTION;
1621 }
1622 }
1623
1624 // notify JVMTI
1625 if (JvmtiExport::should_post_thread_life()) {
1626 JvmtiExport::post_thread_end(this);
1627 }
1628
1629 // We have notified the agents that we are exiting, before we go on,
1630 // we must check for a pending external suspend request and honor it
1631 // in order to not surprise the thread that made the suspend request.
1632 while (true) {
1633 {
1634 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1635 if (!is_external_suspend()) {
1636 set_terminated(_thread_exiting);
1637 ThreadService::current_thread_exiting(this);
1638 break;
1639 }
1640 // Implied else:
1641 // Things get a little tricky here. We have a pending external
1642 // suspend request, but we are holding the SR_lock so we
1643 // can't just self-suspend. So we temporarily drop the lock
1644 // and then self-suspend.
1645 }
1646
1647 ThreadBlockInVM tbivm(this);
1648 java_suspend_self();
1649
1650 // We're done with this suspend request, but we have to loop around
1651 // and check again. Eventually we will get SR_lock without a pending
1652 // external suspend request and will be able to mark ourselves as
1653 // exiting.
1654 }
1655 // no more external suspends are allowed at this point
1656 } else {
1657 // before_exit() has already posted JVMTI THREAD_END events
1658 }
1659
1660 // Notify waiters on thread object. This has to be done after exit() is called
1661 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1662 // group should have the destroyed bit set before waiters are notified).
1663 ensure_join(this);
1664 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1665
1666 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1667 // held by this thread must be released. A detach operation must only
1668 // get here if there are no Java frames on the stack. Therefore, any
1669 // owned monitors at this point MUST be JNI-acquired monitors which are
1670 // pre-inflated and in the monitor cache.
1671 //
1672 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1673 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1674 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1675 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1676 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1677 }
1678
1679 // These things needs to be done while we are still a Java Thread. Make sure that thread
1680 // is in a consistent state, in case GC happens
1681 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1682
1683 if (active_handles() != NULL) {
1684 JNIHandleBlock* block = active_handles();
1685 set_active_handles(NULL);
1686 JNIHandleBlock::release_block(block);
1687 }
1688
1689 if (free_handle_block() != NULL) {
1690 JNIHandleBlock* block = free_handle_block();
1691 set_free_handle_block(NULL);
1692 JNIHandleBlock::release_block(block);
1693 }
1694
1695 // These have to be removed while this is still a valid thread.
1696 remove_stack_guard_pages();
1697
1698 if (UseTLAB) {
1699 tlab().make_parsable(true); // retire TLAB
1700 }
1701
1702 if (jvmti_thread_state() != NULL) {
1703 JvmtiExport::cleanup_thread(this);
1704 }
1705
1706 #ifndef SERIALGC
1707 // We must flush G1-related buffers before removing a thread from
1708 // the list of active threads.
1709 if (UseG1GC) {
1710 flush_barrier_queues();
1711 }
1712 #endif
1713
1714 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1715 Threads::remove(this);
1716 }
1717
1718 #ifndef SERIALGC
1719 // Flush G1-related queues.
1720 void JavaThread::flush_barrier_queues() {
1721 satb_mark_queue().flush();
1722 dirty_card_queue().flush();
1723 }
1724
1725 void JavaThread::initialize_queues() {
1726 assert(!SafepointSynchronize::is_at_safepoint(),
1727 "we should not be at a safepoint");
1728
1729 ObjPtrQueue& satb_queue = satb_mark_queue();
1730 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1731 // The SATB queue should have been constructed with its active
1732 // field set to false.
1733 assert(!satb_queue.is_active(), "SATB queue should not be active");
1734 assert(satb_queue.is_empty(), "SATB queue should be empty");
1735 // If we are creating the thread during a marking cycle, we should
1736 // set the active field of the SATB queue to true.
1737 if (satb_queue_set.is_active()) {
1738 satb_queue.set_active(true);
1739 }
1740
1741 DirtyCardQueue& dirty_queue = dirty_card_queue();
1742 // The dirty card queue should have been constructed with its
1743 // active field set to true.
1744 assert(dirty_queue.is_active(), "dirty card queue should be active");
1745 }
1746 #endif // !SERIALGC
1747
1748 void JavaThread::cleanup_failed_attach_current_thread() {
1749 if (get_thread_profiler() != NULL) {
1750 get_thread_profiler()->disengage();
1751 ResourceMark rm;
1752 get_thread_profiler()->print(get_thread_name());
1753 }
1754
1755 if (active_handles() != NULL) {
1756 JNIHandleBlock* block = active_handles();
1757 set_active_handles(NULL);
1758 JNIHandleBlock::release_block(block);
1759 }
1760
1761 if (free_handle_block() != NULL) {
1762 JNIHandleBlock* block = free_handle_block();
1763 set_free_handle_block(NULL);
1764 JNIHandleBlock::release_block(block);
1765 }
1766
1767 // These have to be removed while this is still a valid thread.
1768 remove_stack_guard_pages();
1769
1770 if (UseTLAB) {
1771 tlab().make_parsable(true); // retire TLAB, if any
1772 }
1773
1774 #ifndef SERIALGC
1775 if (UseG1GC) {
1776 flush_barrier_queues();
1777 }
1778 #endif
1779
1780 Threads::remove(this);
1781 delete this;
1782 }
1783
1784
1785
1786
1787 JavaThread* JavaThread::active() {
1788 Thread* thread = ThreadLocalStorage::thread();
1789 assert(thread != NULL, "just checking");
1790 if (thread->is_Java_thread()) {
1791 return (JavaThread*) thread;
1792 } else {
1793 assert(thread->is_VM_thread(), "this must be a vm thread");
1794 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1795 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1796 assert(ret->is_Java_thread(), "must be a Java thread");
1797 return ret;
1798 }
1799 }
1800
1801 bool JavaThread::is_lock_owned(address adr) const {
1802 if (Thread::is_lock_owned(adr)) return true;
1803
1804 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1805 if (chunk->contains(adr)) return true;
1806 }
1807
1808 return false;
1809 }
1810
1811
1812 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1813 chunk->set_next(monitor_chunks());
1814 set_monitor_chunks(chunk);
1815 }
1816
1817 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1818 guarantee(monitor_chunks() != NULL, "must be non empty");
1819 if (monitor_chunks() == chunk) {
1820 set_monitor_chunks(chunk->next());
1821 } else {
1822 MonitorChunk* prev = monitor_chunks();
1823 while (prev->next() != chunk) prev = prev->next();
1824 prev->set_next(chunk->next());
1825 }
1826 }
1827
1828 // JVM support.
1829
1830 // Note: this function shouldn't block if it's called in
1831 // _thread_in_native_trans state (such as from
1832 // check_special_condition_for_native_trans()).
1833 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1834
1835 if (has_last_Java_frame() && has_async_condition()) {
1836 // If we are at a polling page safepoint (not a poll return)
1837 // then we must defer async exception because live registers
1838 // will be clobbered by the exception path. Poll return is
1839 // ok because the call we a returning from already collides
1840 // with exception handling registers and so there is no issue.
1841 // (The exception handling path kills call result registers but
1842 // this is ok since the exception kills the result anyway).
1843
1844 if (is_at_poll_safepoint()) {
1845 // if the code we are returning to has deoptimized we must defer
1846 // the exception otherwise live registers get clobbered on the
1847 // exception path before deoptimization is able to retrieve them.
1848 //
1849 RegisterMap map(this, false);
1850 frame caller_fr = last_frame().sender(&map);
1851 assert(caller_fr.is_compiled_frame(), "what?");
1852 if (caller_fr.is_deoptimized_frame()) {
1853 if (TraceExceptions) {
1854 ResourceMark rm;
1855 tty->print_cr("deferred async exception at compiled safepoint");
1856 }
1857 return;
1858 }
1859 }
1860 }
1861
1862 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1863 if (condition == _no_async_condition) {
1864 // Conditions have changed since has_special_runtime_exit_condition()
1865 // was called:
1866 // - if we were here only because of an external suspend request,
1867 // then that was taken care of above (or cancelled) so we are done
1868 // - if we were here because of another async request, then it has
1869 // been cleared between the has_special_runtime_exit_condition()
1870 // and now so again we are done
1871 return;
1872 }
1873
1874 // Check for pending async. exception
1875 if (_pending_async_exception != NULL) {
1876 // Only overwrite an already pending exception, if it is not a threadDeath.
1877 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1878
1879 // We cannot call Exceptions::_throw(...) here because we cannot block
1880 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1881
1882 if (TraceExceptions) {
1883 ResourceMark rm;
1884 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1885 if (has_last_Java_frame() ) {
1886 frame f = last_frame();
1887 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1888 }
1889 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1890 }
1891 _pending_async_exception = NULL;
1892 clear_has_async_exception();
1893 }
1894 }
1895
1896 if (check_unsafe_error &&
1897 condition == _async_unsafe_access_error && !has_pending_exception()) {
1898 condition = _no_async_condition; // done
1899 switch (thread_state()) {
1900 case _thread_in_vm:
1901 {
1902 JavaThread* THREAD = this;
1903 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1904 }
1905 case _thread_in_native:
1906 {
1907 ThreadInVMfromNative tiv(this);
1908 JavaThread* THREAD = this;
1909 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1910 }
1911 case _thread_in_Java:
1912 {
1913 ThreadInVMfromJava tiv(this);
1914 JavaThread* THREAD = this;
1915 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1916 }
1917 default:
1918 ShouldNotReachHere();
1919 }
1920 }
1921
1922 assert(condition == _no_async_condition || has_pending_exception() ||
1923 (!check_unsafe_error && condition == _async_unsafe_access_error),
1924 "must have handled the async condition, if no exception");
1925 }
1926
1927 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1928 //
1929 // Check for pending external suspend. Internal suspend requests do
1930 // not use handle_special_runtime_exit_condition().
1931 // If JNIEnv proxies are allowed, don't self-suspend if the target
1932 // thread is not the current thread. In older versions of jdbx, jdbx
1933 // threads could call into the VM with another thread's JNIEnv so we
1934 // can be here operating on behalf of a suspended thread (4432884).
1935 bool do_self_suspend = is_external_suspend_with_lock();
1936 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1937 //
1938 // Because thread is external suspended the safepoint code will count
1939 // thread as at a safepoint. This can be odd because we can be here
1940 // as _thread_in_Java which would normally transition to _thread_blocked
1941 // at a safepoint. We would like to mark the thread as _thread_blocked
1942 // before calling java_suspend_self like all other callers of it but
1943 // we must then observe proper safepoint protocol. (We can't leave
1944 // _thread_blocked with a safepoint in progress). However we can be
1945 // here as _thread_in_native_trans so we can't use a normal transition
1946 // constructor/destructor pair because they assert on that type of
1947 // transition. We could do something like:
1948 //
1949 // JavaThreadState state = thread_state();
1950 // set_thread_state(_thread_in_vm);
1951 // {
1952 // ThreadBlockInVM tbivm(this);
1953 // java_suspend_self()
1954 // }
1955 // set_thread_state(_thread_in_vm_trans);
1956 // if (safepoint) block;
1957 // set_thread_state(state);
1958 //
1959 // but that is pretty messy. Instead we just go with the way the
1960 // code has worked before and note that this is the only path to
1961 // java_suspend_self that doesn't put the thread in _thread_blocked
1962 // mode.
1963
1964 frame_anchor()->make_walkable(this);
1965 java_suspend_self();
1966
1967 // We might be here for reasons in addition to the self-suspend request
1968 // so check for other async requests.
1969 }
1970
1971 if (check_asyncs) {
1972 check_and_handle_async_exceptions();
1973 }
1974 }
1975
1976 void JavaThread::send_thread_stop(oop java_throwable) {
1977 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1978 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1979 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1980
1981 // Do not throw asynchronous exceptions against the compiler thread
1982 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1983 if (is_Compiler_thread()) return;
1984
1985 // This is a change from JDK 1.1, but JDK 1.2 will also do it:
1986 if (java_throwable->is_a(SystemDictionary::ThreadDeath_klass())) {
1987 java_lang_Thread::set_stillborn(threadObj());
1988 }
1989
1990 {
1991 // Actually throw the Throwable against the target Thread - however
1992 // only if there is no thread death exception installed already.
1993 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1994 // If the topmost frame is a runtime stub, then we are calling into
1995 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1996 // must deoptimize the caller before continuing, as the compiled exception handler table
1997 // may not be valid
1998 if (has_last_Java_frame()) {
1999 frame f = last_frame();
2000 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2001 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2002 RegisterMap reg_map(this, UseBiasedLocking);
2003 frame compiled_frame = f.sender(®_map);
2004 if (compiled_frame.can_be_deoptimized()) {
2005 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2006 }
2007 }
2008 }
2009
2010 // Set async. pending exception in thread.
2011 set_pending_async_exception(java_throwable);
2012
2013 if (TraceExceptions) {
2014 ResourceMark rm;
2015 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2016 }
2017 // for AbortVMOnException flag
2018 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2019 }
2020 }
2021
2022
2023 // Interrupt thread so it will wake up from a potential wait()
2024 Thread::interrupt(this);
2025 }
2026
2027 // External suspension mechanism.
2028 //
2029 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2030 // to any VM_locks and it is at a transition
2031 // Self-suspension will happen on the transition out of the vm.
2032 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2033 //
2034 // Guarantees on return:
2035 // + Target thread will not execute any new bytecode (that's why we need to
2036 // force a safepoint)
2037 // + Target thread will not enter any new monitors
2038 //
2039 void JavaThread::java_suspend() {
2040 { MutexLocker mu(Threads_lock);
2041 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2042 return;
2043 }
2044 }
2045
2046 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2047 if (!is_external_suspend()) {
2048 // a racing resume has cancelled us; bail out now
2049 return;
2050 }
2051
2052 // suspend is done
2053 uint32_t debug_bits = 0;
2054 // Warning: is_ext_suspend_completed() may temporarily drop the
2055 // SR_lock to allow the thread to reach a stable thread state if
2056 // it is currently in a transient thread state.
2057 if (is_ext_suspend_completed(false /* !called_by_wait */,
2058 SuspendRetryDelay, &debug_bits) ) {
2059 return;
2060 }
2061 }
2062
2063 VM_ForceSafepoint vm_suspend;
2064 VMThread::execute(&vm_suspend);
2065 }
2066
2067 // Part II of external suspension.
2068 // A JavaThread self suspends when it detects a pending external suspend
2069 // request. This is usually on transitions. It is also done in places
2070 // where continuing to the next transition would surprise the caller,
2071 // e.g., monitor entry.
2072 //
2073 // Returns the number of times that the thread self-suspended.
2074 //
2075 // Note: DO NOT call java_suspend_self() when you just want to block current
2076 // thread. java_suspend_self() is the second stage of cooperative
2077 // suspension for external suspend requests and should only be used
2078 // to complete an external suspend request.
2079 //
2080 int JavaThread::java_suspend_self() {
2081 int ret = 0;
2082
2083 // we are in the process of exiting so don't suspend
2084 if (is_exiting()) {
2085 clear_external_suspend();
2086 return ret;
2087 }
2088
2089 assert(_anchor.walkable() ||
2090 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2091 "must have walkable stack");
2092
2093 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2094
2095 assert(!this->is_ext_suspended(),
2096 "a thread trying to self-suspend should not already be suspended");
2097
2098 if (this->is_suspend_equivalent()) {
2099 // If we are self-suspending as a result of the lifting of a
2100 // suspend equivalent condition, then the suspend_equivalent
2101 // flag is not cleared until we set the ext_suspended flag so
2102 // that wait_for_ext_suspend_completion() returns consistent
2103 // results.
2104 this->clear_suspend_equivalent();
2105 }
2106
2107 // A racing resume may have cancelled us before we grabbed SR_lock
2108 // above. Or another external suspend request could be waiting for us
2109 // by the time we return from SR_lock()->wait(). The thread
2110 // that requested the suspension may already be trying to walk our
2111 // stack and if we return now, we can change the stack out from under
2112 // it. This would be a "bad thing (TM)" and cause the stack walker
2113 // to crash. We stay self-suspended until there are no more pending
2114 // external suspend requests.
2115 while (is_external_suspend()) {
2116 ret++;
2117 this->set_ext_suspended();
2118
2119 // _ext_suspended flag is cleared by java_resume()
2120 while (is_ext_suspended()) {
2121 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2122 }
2123 }
2124
2125 return ret;
2126 }
2127
2128 #ifdef ASSERT
2129 // verify the JavaThread has not yet been published in the Threads::list, and
2130 // hence doesn't need protection from concurrent access at this stage
2131 void JavaThread::verify_not_published() {
2132 if (!Threads_lock->owned_by_self()) {
2133 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2134 assert( !Threads::includes(this),
2135 "java thread shouldn't have been published yet!");
2136 }
2137 else {
2138 assert( !Threads::includes(this),
2139 "java thread shouldn't have been published yet!");
2140 }
2141 }
2142 #endif
2143
2144 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2145 // progress or when _suspend_flags is non-zero.
2146 // Current thread needs to self-suspend if there is a suspend request and/or
2147 // block if a safepoint is in progress.
2148 // Async exception ISN'T checked.
2149 // Note only the ThreadInVMfromNative transition can call this function
2150 // directly and when thread state is _thread_in_native_trans
2151 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2152 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2153
2154 JavaThread *curJT = JavaThread::current();
2155 bool do_self_suspend = thread->is_external_suspend();
2156
2157 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2158
2159 // If JNIEnv proxies are allowed, don't self-suspend if the target
2160 // thread is not the current thread. In older versions of jdbx, jdbx
2161 // threads could call into the VM with another thread's JNIEnv so we
2162 // can be here operating on behalf of a suspended thread (4432884).
2163 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2164 JavaThreadState state = thread->thread_state();
2165
2166 // We mark this thread_blocked state as a suspend-equivalent so
2167 // that a caller to is_ext_suspend_completed() won't be confused.
2168 // The suspend-equivalent state is cleared by java_suspend_self().
2169 thread->set_suspend_equivalent();
2170
2171 // If the safepoint code sees the _thread_in_native_trans state, it will
2172 // wait until the thread changes to other thread state. There is no
2173 // guarantee on how soon we can obtain the SR_lock and complete the
2174 // self-suspend request. It would be a bad idea to let safepoint wait for
2175 // too long. Temporarily change the state to _thread_blocked to
2176 // let the VM thread know that this thread is ready for GC. The problem
2177 // of changing thread state is that safepoint could happen just after
2178 // java_suspend_self() returns after being resumed, and VM thread will
2179 // see the _thread_blocked state. We must check for safepoint
2180 // after restoring the state and make sure we won't leave while a safepoint
2181 // is in progress.
2182 thread->set_thread_state(_thread_blocked);
2183 thread->java_suspend_self();
2184 thread->set_thread_state(state);
2185 // Make sure new state is seen by VM thread
2186 if (os::is_MP()) {
2187 if (UseMembar) {
2188 // Force a fence between the write above and read below
2189 OrderAccess::fence();
2190 } else {
2191 // Must use this rather than serialization page in particular on Windows
2192 InterfaceSupport::serialize_memory(thread);
2193 }
2194 }
2195 }
2196
2197 if (SafepointSynchronize::do_call_back()) {
2198 // If we are safepointing, then block the caller which may not be
2199 // the same as the target thread (see above).
2200 SafepointSynchronize::block(curJT);
2201 }
2202
2203 if (thread->is_deopt_suspend()) {
2204 thread->clear_deopt_suspend();
2205 RegisterMap map(thread, false);
2206 frame f = thread->last_frame();
2207 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2208 f = f.sender(&map);
2209 }
2210 if (f.id() == thread->must_deopt_id()) {
2211 thread->clear_must_deopt_id();
2212 f.deoptimize(thread);
2213 } else {
2214 fatal("missed deoptimization!");
2215 }
2216 }
2217 }
2218
2219 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2220 // progress or when _suspend_flags is non-zero.
2221 // Current thread needs to self-suspend if there is a suspend request and/or
2222 // block if a safepoint is in progress.
2223 // Also check for pending async exception (not including unsafe access error).
2224 // Note only the native==>VM/Java barriers can call this function and when
2225 // thread state is _thread_in_native_trans.
2226 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2227 check_safepoint_and_suspend_for_native_trans(thread);
2228
2229 if (thread->has_async_exception()) {
2230 // We are in _thread_in_native_trans state, don't handle unsafe
2231 // access error since that may block.
2232 thread->check_and_handle_async_exceptions(false);
2233 }
2234 }
2235
2236 // We need to guarantee the Threads_lock here, since resumes are not
2237 // allowed during safepoint synchronization
2238 // Can only resume from an external suspension
2239 void JavaThread::java_resume() {
2240 assert_locked_or_safepoint(Threads_lock);
2241
2242 // Sanity check: thread is gone, has started exiting or the thread
2243 // was not externally suspended.
2244 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2245 return;
2246 }
2247
2248 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2249
2250 clear_external_suspend();
2251
2252 if (is_ext_suspended()) {
2253 clear_ext_suspended();
2254 SR_lock()->notify_all();
2255 }
2256 }
2257
2258 void JavaThread::create_stack_guard_pages() {
2259 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2260 address low_addr = stack_base() - stack_size();
2261 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2262
2263 int allocate = os::allocate_stack_guard_pages();
2264 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2265
2266 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2267 warning("Attempt to allocate stack guard pages failed.");
2268 return;
2269 }
2270
2271 if (os::guard_memory((char *) low_addr, len)) {
2272 _stack_guard_state = stack_guard_enabled;
2273 } else {
2274 warning("Attempt to protect stack guard pages failed.");
2275 if (os::uncommit_memory((char *) low_addr, len)) {
2276 warning("Attempt to deallocate stack guard pages failed.");
2277 }
2278 }
2279 }
2280
2281 void JavaThread::remove_stack_guard_pages() {
2282 if (_stack_guard_state == stack_guard_unused) return;
2283 address low_addr = stack_base() - stack_size();
2284 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2285
2286 if (os::allocate_stack_guard_pages()) {
2287 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2288 _stack_guard_state = stack_guard_unused;
2289 } else {
2290 warning("Attempt to deallocate stack guard pages failed.");
2291 }
2292 } else {
2293 if (_stack_guard_state == stack_guard_unused) return;
2294 if (os::unguard_memory((char *) low_addr, len)) {
2295 _stack_guard_state = stack_guard_unused;
2296 } else {
2297 warning("Attempt to unprotect stack guard pages failed.");
2298 }
2299 }
2300 }
2301
2302 void JavaThread::enable_stack_yellow_zone() {
2303 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2304 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2305
2306 // The base notation is from the stacks point of view, growing downward.
2307 // We need to adjust it to work correctly with guard_memory()
2308 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2309
2310 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2311 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2312
2313 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2314 _stack_guard_state = stack_guard_enabled;
2315 } else {
2316 warning("Attempt to guard stack yellow zone failed.");
2317 }
2318 enable_register_stack_guard();
2319 }
2320
2321 void JavaThread::disable_stack_yellow_zone() {
2322 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2323 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2324
2325 // Simply return if called for a thread that does not use guard pages.
2326 if (_stack_guard_state == stack_guard_unused) return;
2327
2328 // The base notation is from the stacks point of view, growing downward.
2329 // We need to adjust it to work correctly with guard_memory()
2330 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2331
2332 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2333 _stack_guard_state = stack_guard_yellow_disabled;
2334 } else {
2335 warning("Attempt to unguard stack yellow zone failed.");
2336 }
2337 disable_register_stack_guard();
2338 }
2339
2340 void JavaThread::enable_stack_red_zone() {
2341 // The base notation is from the stacks point of view, growing downward.
2342 // We need to adjust it to work correctly with guard_memory()
2343 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2344 address base = stack_red_zone_base() - stack_red_zone_size();
2345
2346 guarantee(base < stack_base(),"Error calculating stack red zone");
2347 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2348
2349 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2350 warning("Attempt to guard stack red zone failed.");
2351 }
2352 }
2353
2354 void JavaThread::disable_stack_red_zone() {
2355 // The base notation is from the stacks point of view, growing downward.
2356 // We need to adjust it to work correctly with guard_memory()
2357 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2358 address base = stack_red_zone_base() - stack_red_zone_size();
2359 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2360 warning("Attempt to unguard stack red zone failed.");
2361 }
2362 }
2363
2364 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2365 // ignore is there is no stack
2366 if (!has_last_Java_frame()) return;
2367 // traverse the stack frames. Starts from top frame.
2368 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2369 frame* fr = fst.current();
2370 f(fr, fst.register_map());
2371 }
2372 }
2373
2374
2375 #ifndef PRODUCT
2376 // Deoptimization
2377 // Function for testing deoptimization
2378 void JavaThread::deoptimize() {
2379 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2380 StackFrameStream fst(this, UseBiasedLocking);
2381 bool deopt = false; // Dump stack only if a deopt actually happens.
2382 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2383 // Iterate over all frames in the thread and deoptimize
2384 for(; !fst.is_done(); fst.next()) {
2385 if(fst.current()->can_be_deoptimized()) {
2386
2387 if (only_at) {
2388 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2389 // consists of comma or carriage return separated numbers so
2390 // search for the current bci in that string.
2391 address pc = fst.current()->pc();
2392 nmethod* nm = (nmethod*) fst.current()->cb();
2393 ScopeDesc* sd = nm->scope_desc_at( pc);
2394 char buffer[8];
2395 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2396 size_t len = strlen(buffer);
2397 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2398 while (found != NULL) {
2399 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2400 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2401 // Check that the bci found is bracketed by terminators.
2402 break;
2403 }
2404 found = strstr(found + 1, buffer);
2405 }
2406 if (!found) {
2407 continue;
2408 }
2409 }
2410
2411 if (DebugDeoptimization && !deopt) {
2412 deopt = true; // One-time only print before deopt
2413 tty->print_cr("[BEFORE Deoptimization]");
2414 trace_frames();
2415 trace_stack();
2416 }
2417 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2418 }
2419 }
2420
2421 if (DebugDeoptimization && deopt) {
2422 tty->print_cr("[AFTER Deoptimization]");
2423 trace_frames();
2424 }
2425 }
2426
2427
2428 // Make zombies
2429 void JavaThread::make_zombies() {
2430 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2431 if (fst.current()->can_be_deoptimized()) {
2432 // it is a Java nmethod
2433 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2434 nm->make_not_entrant();
2435 }
2436 }
2437 }
2438 #endif // PRODUCT
2439
2440
2441 void JavaThread::deoptimized_wrt_marked_nmethods() {
2442 if (!has_last_Java_frame()) return;
2443 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2444 StackFrameStream fst(this, UseBiasedLocking);
2445 for(; !fst.is_done(); fst.next()) {
2446 if (fst.current()->should_be_deoptimized()) {
2447 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2448 }
2449 }
2450 }
2451
2452
2453 // GC support
2454 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2455
2456 void JavaThread::gc_epilogue() {
2457 frames_do(frame_gc_epilogue);
2458 }
2459
2460
2461 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2462
2463 void JavaThread::gc_prologue() {
2464 frames_do(frame_gc_prologue);
2465 }
2466
2467 // If the caller is a NamedThread, then remember, in the current scope,
2468 // the given JavaThread in its _processed_thread field.
2469 class RememberProcessedThread: public StackObj {
2470 NamedThread* _cur_thr;
2471 public:
2472 RememberProcessedThread(JavaThread* jthr) {
2473 Thread* thread = Thread::current();
2474 if (thread->is_Named_thread()) {
2475 _cur_thr = (NamedThread *)thread;
2476 _cur_thr->set_processed_thread(jthr);
2477 } else {
2478 _cur_thr = NULL;
2479 }
2480 }
2481
2482 ~RememberProcessedThread() {
2483 if (_cur_thr) {
2484 _cur_thr->set_processed_thread(NULL);
2485 }
2486 }
2487 };
2488
2489 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2490 // Verify that the deferred card marks have been flushed.
2491 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2492
2493 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2494 // since there may be more than one thread using each ThreadProfiler.
2495
2496 // Traverse the GCHandles
2497 Thread::oops_do(f, cf);
2498
2499 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2500 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2501
2502 if (has_last_Java_frame()) {
2503 // Record JavaThread to GC thread
2504 RememberProcessedThread rpt(this);
2505
2506 // Traverse the privileged stack
2507 if (_privileged_stack_top != NULL) {
2508 _privileged_stack_top->oops_do(f);
2509 }
2510
2511 // traverse the registered growable array
2512 if (_array_for_gc != NULL) {
2513 for (int index = 0; index < _array_for_gc->length(); index++) {
2514 f->do_oop(_array_for_gc->adr_at(index));
2515 }
2516 }
2517
2518 // Traverse the monitor chunks
2519 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2520 chunk->oops_do(f);
2521 }
2522
2523 // Traverse the execution stack
2524 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2525 fst.current()->oops_do(f, cf, fst.register_map());
2526 }
2527 }
2528
2529 // callee_target is never live across a gc point so NULL it here should
2530 // it still contain a methdOop.
2531
2532 set_callee_target(NULL);
2533
2534 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2535 // If we have deferred set_locals there might be oops waiting to be
2536 // written
2537 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2538 if (list != NULL) {
2539 for (int i = 0; i < list->length(); i++) {
2540 list->at(i)->oops_do(f);
2541 }
2542 }
2543
2544 // Traverse instance variables at the end since the GC may be moving things
2545 // around using this function
2546 f->do_oop((oop*) &_threadObj);
2547 f->do_oop((oop*) &_vm_result);
2548 f->do_oop((oop*) &_vm_result_2);
2549 f->do_oop((oop*) &_exception_oop);
2550 f->do_oop((oop*) &_pending_async_exception);
2551
2552 if (jvmti_thread_state() != NULL) {
2553 jvmti_thread_state()->oops_do(f);
2554 }
2555 }
2556
2557 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2558 Thread::nmethods_do(cf); // (super method is a no-op)
2559
2560 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2561 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2562
2563 if (has_last_Java_frame()) {
2564 // Traverse the execution stack
2565 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2566 fst.current()->nmethods_do(cf);
2567 }
2568 }
2569 }
2570
2571 // Printing
2572 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2573 switch (_thread_state) {
2574 case _thread_uninitialized: return "_thread_uninitialized";
2575 case _thread_new: return "_thread_new";
2576 case _thread_new_trans: return "_thread_new_trans";
2577 case _thread_in_native: return "_thread_in_native";
2578 case _thread_in_native_trans: return "_thread_in_native_trans";
2579 case _thread_in_vm: return "_thread_in_vm";
2580 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2581 case _thread_in_Java: return "_thread_in_Java";
2582 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2583 case _thread_blocked: return "_thread_blocked";
2584 case _thread_blocked_trans: return "_thread_blocked_trans";
2585 default: return "unknown thread state";
2586 }
2587 }
2588
2589 #ifndef PRODUCT
2590 void JavaThread::print_thread_state_on(outputStream *st) const {
2591 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2592 };
2593 void JavaThread::print_thread_state() const {
2594 print_thread_state_on(tty);
2595 };
2596 #endif // PRODUCT
2597
2598 // Called by Threads::print() for VM_PrintThreads operation
2599 void JavaThread::print_on(outputStream *st) const {
2600 st->print("\"%s\" ", get_thread_name());
2601 oop thread_oop = threadObj();
2602 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2603 Thread::print_on(st);
2604 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2605 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2606 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2607 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2608 }
2609 #ifndef PRODUCT
2610 print_thread_state_on(st);
2611 _safepoint_state->print_on(st);
2612 #endif // PRODUCT
2613 }
2614
2615 // Called by fatal error handler. The difference between this and
2616 // JavaThread::print() is that we can't grab lock or allocate memory.
2617 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2618 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2619 oop thread_obj = threadObj();
2620 if (thread_obj != NULL) {
2621 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2622 }
2623 st->print(" [");
2624 st->print("%s", _get_thread_state_name(_thread_state));
2625 if (osthread()) {
2626 st->print(", id=%d", osthread()->thread_id());
2627 }
2628 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2629 _stack_base - _stack_size, _stack_base);
2630 st->print("]");
2631 return;
2632 }
2633
2634 // Verification
2635
2636 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2637
2638 void JavaThread::verify() {
2639 // Verify oops in the thread.
2640 oops_do(&VerifyOopClosure::verify_oop, NULL);
2641
2642 // Verify the stack frames.
2643 frames_do(frame_verify);
2644 }
2645
2646 // CR 6300358 (sub-CR 2137150)
2647 // Most callers of this method assume that it can't return NULL but a
2648 // thread may not have a name whilst it is in the process of attaching to
2649 // the VM - see CR 6412693, and there are places where a JavaThread can be
2650 // seen prior to having it's threadObj set (eg JNI attaching threads and
2651 // if vm exit occurs during initialization). These cases can all be accounted
2652 // for such that this method never returns NULL.
2653 const char* JavaThread::get_thread_name() const {
2654 #ifdef ASSERT
2655 // early safepoints can hit while current thread does not yet have TLS
2656 if (!SafepointSynchronize::is_at_safepoint()) {
2657 Thread *cur = Thread::current();
2658 if (!(cur->is_Java_thread() && cur == this)) {
2659 // Current JavaThreads are allowed to get their own name without
2660 // the Threads_lock.
2661 assert_locked_or_safepoint(Threads_lock);
2662 }
2663 }
2664 #endif // ASSERT
2665 return get_thread_name_string();
2666 }
2667
2668 // Returns a non-NULL representation of this thread's name, or a suitable
2669 // descriptive string if there is no set name
2670 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2671 const char* name_str;
2672 oop thread_obj = threadObj();
2673 if (thread_obj != NULL) {
2674 typeArrayOop name = java_lang_Thread::name(thread_obj);
2675 if (name != NULL) {
2676 if (buf == NULL) {
2677 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2678 }
2679 else {
2680 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2681 }
2682 }
2683 else if (is_attaching()) { // workaround for 6412693 - see 6404306
2684 name_str = "<no-name - thread is attaching>";
2685 }
2686 else {
2687 name_str = Thread::name();
2688 }
2689 }
2690 else {
2691 name_str = Thread::name();
2692 }
2693 assert(name_str != NULL, "unexpected NULL thread name");
2694 return name_str;
2695 }
2696
2697
2698 const char* JavaThread::get_threadgroup_name() const {
2699 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2700 oop thread_obj = threadObj();
2701 if (thread_obj != NULL) {
2702 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2703 if (thread_group != NULL) {
2704 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2705 // ThreadGroup.name can be null
2706 if (name != NULL) {
2707 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2708 return str;
2709 }
2710 }
2711 }
2712 return NULL;
2713 }
2714
2715 const char* JavaThread::get_parent_name() const {
2716 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2717 oop thread_obj = threadObj();
2718 if (thread_obj != NULL) {
2719 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2720 if (thread_group != NULL) {
2721 oop parent = java_lang_ThreadGroup::parent(thread_group);
2722 if (parent != NULL) {
2723 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2724 // ThreadGroup.name can be null
2725 if (name != NULL) {
2726 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2727 return str;
2728 }
2729 }
2730 }
2731 }
2732 return NULL;
2733 }
2734
2735 ThreadPriority JavaThread::java_priority() const {
2736 oop thr_oop = threadObj();
2737 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2738 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2739 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2740 return priority;
2741 }
2742
2743 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2744
2745 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2746 // Link Java Thread object <-> C++ Thread
2747
2748 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2749 // and put it into a new Handle. The Handle "thread_oop" can then
2750 // be used to pass the C++ thread object to other methods.
2751
2752 // Set the Java level thread object (jthread) field of the
2753 // new thread (a JavaThread *) to C++ thread object using the
2754 // "thread_oop" handle.
2755
2756 // Set the thread field (a JavaThread *) of the
2757 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2758
2759 Handle thread_oop(Thread::current(),
2760 JNIHandles::resolve_non_null(jni_thread));
2761 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2762 "must be initialized");
2763 set_threadObj(thread_oop());
2764 java_lang_Thread::set_thread(thread_oop(), this);
2765
2766 if (prio == NoPriority) {
2767 prio = java_lang_Thread::priority(thread_oop());
2768 assert(prio != NoPriority, "A valid priority should be present");
2769 }
2770
2771 // Push the Java priority down to the native thread; needs Threads_lock
2772 Thread::set_priority(this, prio);
2773
2774 // Add the new thread to the Threads list and set it in motion.
2775 // We must have threads lock in order to call Threads::add.
2776 // It is crucial that we do not block before the thread is
2777 // added to the Threads list for if a GC happens, then the java_thread oop
2778 // will not be visited by GC.
2779 Threads::add(this);
2780 }
2781
2782 oop JavaThread::current_park_blocker() {
2783 // Support for JSR-166 locks
2784 oop thread_oop = threadObj();
2785 if (thread_oop != NULL &&
2786 JDK_Version::current().supports_thread_park_blocker()) {
2787 return java_lang_Thread::park_blocker(thread_oop);
2788 }
2789 return NULL;
2790 }
2791
2792
2793 void JavaThread::print_stack_on(outputStream* st) {
2794 if (!has_last_Java_frame()) return;
2795 ResourceMark rm;
2796 HandleMark hm;
2797
2798 RegisterMap reg_map(this);
2799 vframe* start_vf = last_java_vframe(®_map);
2800 int count = 0;
2801 for (vframe* f = start_vf; f; f = f->sender() ) {
2802 if (f->is_java_frame()) {
2803 javaVFrame* jvf = javaVFrame::cast(f);
2804 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2805
2806 // Print out lock information
2807 if (JavaMonitorsInStackTrace) {
2808 jvf->print_lock_info_on(st, count);
2809 }
2810 } else {
2811 // Ignore non-Java frames
2812 }
2813
2814 // Bail-out case for too deep stacks
2815 count++;
2816 if (MaxJavaStackTraceDepth == count) return;
2817 }
2818 }
2819
2820
2821 // JVMTI PopFrame support
2822 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2823 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2824 if (in_bytes(size_in_bytes) != 0) {
2825 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2826 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2827 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2828 }
2829 }
2830
2831 void* JavaThread::popframe_preserved_args() {
2832 return _popframe_preserved_args;
2833 }
2834
2835 ByteSize JavaThread::popframe_preserved_args_size() {
2836 return in_ByteSize(_popframe_preserved_args_size);
2837 }
2838
2839 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2840 int sz = in_bytes(popframe_preserved_args_size());
2841 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2842 return in_WordSize(sz / wordSize);
2843 }
2844
2845 void JavaThread::popframe_free_preserved_args() {
2846 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2847 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2848 _popframe_preserved_args = NULL;
2849 _popframe_preserved_args_size = 0;
2850 }
2851
2852 #ifndef PRODUCT
2853
2854 void JavaThread::trace_frames() {
2855 tty->print_cr("[Describe stack]");
2856 int frame_no = 1;
2857 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2858 tty->print(" %d. ", frame_no++);
2859 fst.current()->print_value_on(tty,this);
2860 tty->cr();
2861 }
2862 }
2863
2864
2865 void JavaThread::trace_stack_from(vframe* start_vf) {
2866 ResourceMark rm;
2867 int vframe_no = 1;
2868 for (vframe* f = start_vf; f; f = f->sender() ) {
2869 if (f->is_java_frame()) {
2870 javaVFrame::cast(f)->print_activation(vframe_no++);
2871 } else {
2872 f->print();
2873 }
2874 if (vframe_no > StackPrintLimit) {
2875 tty->print_cr("...<more frames>...");
2876 return;
2877 }
2878 }
2879 }
2880
2881
2882 void JavaThread::trace_stack() {
2883 if (!has_last_Java_frame()) return;
2884 ResourceMark rm;
2885 HandleMark hm;
2886 RegisterMap reg_map(this);
2887 trace_stack_from(last_java_vframe(®_map));
2888 }
2889
2890
2891 #endif // PRODUCT
2892
2893
2894 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2895 assert(reg_map != NULL, "a map must be given");
2896 frame f = last_frame();
2897 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2898 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2899 }
2900 return NULL;
2901 }
2902
2903
2904 klassOop JavaThread::security_get_caller_class(int depth) {
2905 vframeStream vfst(this);
2906 vfst.security_get_caller_frame(depth);
2907 if (!vfst.at_end()) {
2908 return vfst.method()->method_holder();
2909 }
2910 return NULL;
2911 }
2912
2913 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2914 assert(thread->is_Compiler_thread(), "must be compiler thread");
2915 CompileBroker::compiler_thread_loop();
2916 }
2917
2918 // Create a CompilerThread
2919 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2920 : JavaThread(&compiler_thread_entry) {
2921 _env = NULL;
2922 _log = NULL;
2923 _task = NULL;
2924 _queue = queue;
2925 _counters = counters;
2926 _buffer_blob = NULL;
2927
2928 #ifndef PRODUCT
2929 _ideal_graph_printer = NULL;
2930 #endif
2931 }
2932
2933
2934 // ======= Threads ========
2935
2936 // The Threads class links together all active threads, and provides
2937 // operations over all threads. It is protected by its own Mutex
2938 // lock, which is also used in other contexts to protect thread
2939 // operations from having the thread being operated on from exiting
2940 // and going away unexpectedly (e.g., safepoint synchronization)
2941
2942 JavaThread* Threads::_thread_list = NULL;
2943 int Threads::_number_of_threads = 0;
2944 int Threads::_number_of_non_daemon_threads = 0;
2945 int Threads::_return_code = 0;
2946 size_t JavaThread::_stack_size_at_create = 0;
2947
2948 // All JavaThreads
2949 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2950
2951 void os_stream();
2952
2953 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2954 void Threads::threads_do(ThreadClosure* tc) {
2955 assert_locked_or_safepoint(Threads_lock);
2956 // ALL_JAVA_THREADS iterates through all JavaThreads
2957 ALL_JAVA_THREADS(p) {
2958 tc->do_thread(p);
2959 }
2960 // Someday we could have a table or list of all non-JavaThreads.
2961 // For now, just manually iterate through them.
2962 tc->do_thread(VMThread::vm_thread());
2963 Universe::heap()->gc_threads_do(tc);
2964 WatcherThread *wt = WatcherThread::watcher_thread();
2965 // Strictly speaking, the following NULL check isn't sufficient to make sure
2966 // the data for WatcherThread is still valid upon being examined. However,
2967 // considering that WatchThread terminates when the VM is on the way to
2968 // exit at safepoint, the chance of the above is extremely small. The right
2969 // way to prevent termination of WatcherThread would be to acquire
2970 // Terminator_lock, but we can't do that without violating the lock rank
2971 // checking in some cases.
2972 if (wt != NULL)
2973 tc->do_thread(wt);
2974
2975 // If CompilerThreads ever become non-JavaThreads, add them here
2976 }
2977
2978 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2979
2980 extern void JDK_Version_init();
2981
2982 // Check version
2983 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2984
2985 // Initialize the output stream module
2986 ostream_init();
2987
2988 // Process java launcher properties.
2989 Arguments::process_sun_java_launcher_properties(args);
2990
2991 // Initialize the os module before using TLS
2992 os::init();
2993
2994 // Initialize system properties.
2995 Arguments::init_system_properties();
2996
2997 // So that JDK version can be used as a discrimintor when parsing arguments
2998 JDK_Version_init();
2999
3000 // Update/Initialize System properties after JDK version number is known
3001 Arguments::init_version_specific_system_properties();
3002
3003 // Parse arguments
3004 jint parse_result = Arguments::parse(args);
3005 if (parse_result != JNI_OK) return parse_result;
3006
3007 if (PauseAtStartup) {
3008 os::pause();
3009 }
3010
3011 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3012
3013 // Record VM creation timing statistics
3014 TraceVmCreationTime create_vm_timer;
3015 create_vm_timer.start();
3016
3017 // Timing (must come after argument parsing)
3018 TraceTime timer("Create VM", TraceStartupTime);
3019
3020 // Initialize the os module after parsing the args
3021 jint os_init_2_result = os::init_2();
3022 if (os_init_2_result != JNI_OK) return os_init_2_result;
3023
3024 // Initialize output stream logging
3025 ostream_init_log();
3026
3027 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3028 // Must be before create_vm_init_agents()
3029 if (Arguments::init_libraries_at_startup()) {
3030 convert_vm_init_libraries_to_agents();
3031 }
3032
3033 // Launch -agentlib/-agentpath and converted -Xrun agents
3034 if (Arguments::init_agents_at_startup()) {
3035 create_vm_init_agents();
3036 }
3037
3038 // Initialize Threads state
3039 _thread_list = NULL;
3040 _number_of_threads = 0;
3041 _number_of_non_daemon_threads = 0;
3042
3043 // Initialize TLS
3044 ThreadLocalStorage::init();
3045
3046 // Initialize global data structures and create system classes in heap
3047 vm_init_globals();
3048
3049 // Attach the main thread to this os thread
3050 JavaThread* main_thread = new JavaThread();
3051 main_thread->set_thread_state(_thread_in_vm);
3052 // must do this before set_active_handles and initialize_thread_local_storage
3053 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3054 // change the stack size recorded here to one based on the java thread
3055 // stacksize. This adjusted size is what is used to figure the placement
3056 // of the guard pages.
3057 main_thread->record_stack_base_and_size();
3058 main_thread->initialize_thread_local_storage();
3059
3060 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3061
3062 if (!main_thread->set_as_starting_thread()) {
3063 vm_shutdown_during_initialization(
3064 "Failed necessary internal allocation. Out of swap space");
3065 delete main_thread;
3066 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3067 return JNI_ENOMEM;
3068 }
3069
3070 // Enable guard page *after* os::create_main_thread(), otherwise it would
3071 // crash Linux VM, see notes in os_linux.cpp.
3072 main_thread->create_stack_guard_pages();
3073
3074 // Initialize Java-Level synchronization subsystem
3075 ObjectMonitor::Initialize() ;
3076
3077 // Initialize global modules
3078 jint status = init_globals();
3079 if (status != JNI_OK) {
3080 delete main_thread;
3081 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3082 return status;
3083 }
3084
3085 // Should be done after the heap is fully created
3086 main_thread->cache_global_variables();
3087
3088 HandleMark hm;
3089
3090 { MutexLocker mu(Threads_lock);
3091 Threads::add(main_thread);
3092 }
3093
3094 // Any JVMTI raw monitors entered in onload will transition into
3095 // real raw monitor. VM is setup enough here for raw monitor enter.
3096 JvmtiExport::transition_pending_onload_raw_monitors();
3097
3098 if (VerifyBeforeGC &&
3099 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3100 Universe::heap()->prepare_for_verify();
3101 Universe::verify(); // make sure we're starting with a clean slate
3102 }
3103
3104 // Create the VMThread
3105 { TraceTime timer("Start VMThread", TraceStartupTime);
3106 VMThread::create();
3107 Thread* vmthread = VMThread::vm_thread();
3108
3109 if (!os::create_thread(vmthread, os::vm_thread))
3110 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3111
3112 // Wait for the VM thread to become ready, and VMThread::run to initialize
3113 // Monitors can have spurious returns, must always check another state flag
3114 {
3115 MutexLocker ml(Notify_lock);
3116 os::start_thread(vmthread);
3117 while (vmthread->active_handles() == NULL) {
3118 Notify_lock->wait();
3119 }
3120 }
3121 }
3122
3123 assert (Universe::is_fully_initialized(), "not initialized");
3124 EXCEPTION_MARK;
3125
3126 // At this point, the Universe is initialized, but we have not executed
3127 // any byte code. Now is a good time (the only time) to dump out the
3128 // internal state of the JVM for sharing.
3129
3130 if (DumpSharedSpaces) {
3131 Universe::heap()->preload_and_dump(CHECK_0);
3132 ShouldNotReachHere();
3133 }
3134
3135 // Always call even when there are not JVMTI environments yet, since environments
3136 // may be attached late and JVMTI must track phases of VM execution
3137 JvmtiExport::enter_start_phase();
3138
3139 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3140 JvmtiExport::post_vm_start();
3141
3142 {
3143 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3144
3145 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3146 create_vm_init_libraries();
3147 }
3148
3149 if (InitializeJavaLangString) {
3150 initialize_class(vmSymbolHandles::java_lang_String(), CHECK_0);
3151 } else {
3152 warning("java.lang.String not initialized");
3153 }
3154
3155 if (AggressiveOpts) {
3156 {
3157 // Forcibly initialize java/util/HashMap and mutate the private
3158 // static final "frontCacheEnabled" field before we start creating instances
3159 #ifdef ASSERT
3160 klassOop tmp_k = SystemDictionary::find(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3161 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3162 #endif
3163 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3164 KlassHandle k = KlassHandle(THREAD, k_o);
3165 guarantee(k.not_null(), "Must find java/util/HashMap");
3166 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3167 ik->initialize(CHECK_0);
3168 fieldDescriptor fd;
3169 // Possible we might not find this field; if so, don't break
3170 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3171 k()->bool_field_put(fd.offset(), true);
3172 }
3173 }
3174
3175 if (UseStringCache) {
3176 // Forcibly initialize java/lang/StringValue and mutate the private
3177 // static final "stringCacheEnabled" field before we start creating instances
3178 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3179 // Possible that StringValue isn't present: if so, silently don't break
3180 if (k_o != NULL) {
3181 KlassHandle k = KlassHandle(THREAD, k_o);
3182 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3183 ik->initialize(CHECK_0);
3184 fieldDescriptor fd;
3185 // Possible we might not find this field: if so, silently don't break
3186 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3187 k()->bool_field_put(fd.offset(), true);
3188 }
3189 }
3190 }
3191 }
3192
3193 // Initialize java_lang.System (needed before creating the thread)
3194 if (InitializeJavaLangSystem) {
3195 initialize_class(vmSymbolHandles::java_lang_System(), CHECK_0);
3196 initialize_class(vmSymbolHandles::java_lang_ThreadGroup(), CHECK_0);
3197 Handle thread_group = create_initial_thread_group(CHECK_0);
3198 Universe::set_main_thread_group(thread_group());
3199 initialize_class(vmSymbolHandles::java_lang_Thread(), CHECK_0);
3200 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3201 main_thread->set_threadObj(thread_object);
3202 // Set thread status to running since main thread has
3203 // been started and running.
3204 java_lang_Thread::set_thread_status(thread_object,
3205 java_lang_Thread::RUNNABLE);
3206
3207 // The VM preresolve methods to these classes. Make sure that get initialized
3208 initialize_class(vmSymbolHandles::java_lang_reflect_Method(), CHECK_0);
3209 initialize_class(vmSymbolHandles::java_lang_ref_Finalizer(), CHECK_0);
3210 // The VM creates & returns objects of this class. Make sure it's initialized.
3211 initialize_class(vmSymbolHandles::java_lang_Class(), CHECK_0);
3212 call_initializeSystemClass(CHECK_0);
3213 } else {
3214 warning("java.lang.System not initialized");
3215 }
3216
3217 // an instance of OutOfMemory exception has been allocated earlier
3218 if (InitializeJavaLangExceptionsErrors) {
3219 initialize_class(vmSymbolHandles::java_lang_OutOfMemoryError(), CHECK_0);
3220 initialize_class(vmSymbolHandles::java_lang_NullPointerException(), CHECK_0);
3221 initialize_class(vmSymbolHandles::java_lang_ClassCastException(), CHECK_0);
3222 initialize_class(vmSymbolHandles::java_lang_ArrayStoreException(), CHECK_0);
3223 initialize_class(vmSymbolHandles::java_lang_ArithmeticException(), CHECK_0);
3224 initialize_class(vmSymbolHandles::java_lang_StackOverflowError(), CHECK_0);
3225 initialize_class(vmSymbolHandles::java_lang_IllegalMonitorStateException(), CHECK_0);
3226 } else {
3227 warning("java.lang.OutOfMemoryError has not been initialized");
3228 warning("java.lang.NullPointerException has not been initialized");
3229 warning("java.lang.ClassCastException has not been initialized");
3230 warning("java.lang.ArrayStoreException has not been initialized");
3231 warning("java.lang.ArithmeticException has not been initialized");
3232 warning("java.lang.StackOverflowError has not been initialized");
3233 }
3234 }
3235
3236 // See : bugid 4211085.
3237 // Background : the static initializer of java.lang.Compiler tries to read
3238 // property"java.compiler" and read & write property "java.vm.info".
3239 // When a security manager is installed through the command line
3240 // option "-Djava.security.manager", the above properties are not
3241 // readable and the static initializer for java.lang.Compiler fails
3242 // resulting in a NoClassDefFoundError. This can happen in any
3243 // user code which calls methods in java.lang.Compiler.
3244 // Hack : the hack is to pre-load and initialize this class, so that only
3245 // system domains are on the stack when the properties are read.
3246 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3247 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3248 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3249 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3250 // Once that is done, we should remove this hack.
3251 initialize_class(vmSymbolHandles::java_lang_Compiler(), CHECK_0);
3252
3253 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3254 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3255 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3256 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3257 // This should also be taken out as soon as 4211383 gets fixed.
3258 reset_vm_info_property(CHECK_0);
3259
3260 quicken_jni_functions();
3261
3262 // Set flag that basic initialization has completed. Used by exceptions and various
3263 // debug stuff, that does not work until all basic classes have been initialized.
3264 set_init_completed();
3265
3266 HS_DTRACE_PROBE(hotspot, vm__init__end);
3267
3268 // record VM initialization completion time
3269 Management::record_vm_init_completed();
3270
3271 // Compute system loader. Note that this has to occur after set_init_completed, since
3272 // valid exceptions may be thrown in the process.
3273 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3274 // set_init_completed has just been called, causing exceptions not to be shortcut
3275 // anymore. We call vm_exit_during_initialization directly instead.
3276 SystemDictionary::compute_java_system_loader(THREAD);
3277 if (HAS_PENDING_EXCEPTION) {
3278 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3279 }
3280
3281 #ifdef KERNEL
3282 if (JDK_Version::is_gte_jdk17x_version()) {
3283 set_jkernel_boot_classloader_hook(THREAD);
3284 }
3285 #endif // KERNEL
3286
3287 #ifndef SERIALGC
3288 // Support for ConcurrentMarkSweep. This should be cleaned up
3289 // and better encapsulated. The ugly nested if test would go away
3290 // once things are properly refactored. XXX YSR
3291 if (UseConcMarkSweepGC || UseG1GC) {
3292 if (UseConcMarkSweepGC) {
3293 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3294 } else {
3295 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3296 }
3297 if (HAS_PENDING_EXCEPTION) {
3298 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3299 }
3300 }
3301 #endif // SERIALGC
3302
3303 // Always call even when there are not JVMTI environments yet, since environments
3304 // may be attached late and JVMTI must track phases of VM execution
3305 JvmtiExport::enter_live_phase();
3306
3307 // Signal Dispatcher needs to be started before VMInit event is posted
3308 os::signal_init();
3309
3310 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3311 if (!DisableAttachMechanism) {
3312 if (StartAttachListener || AttachListener::init_at_startup()) {
3313 AttachListener::init();
3314 }
3315 }
3316
3317 // Launch -Xrun agents
3318 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3319 // back-end can launch with -Xdebug -Xrunjdwp.
3320 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3321 create_vm_init_libraries();
3322 }
3323
3324 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3325 JvmtiExport::post_vm_initialized();
3326
3327 Chunk::start_chunk_pool_cleaner_task();
3328
3329 // initialize compiler(s)
3330 CompileBroker::compilation_init();
3331
3332 Management::initialize(THREAD);
3333 if (HAS_PENDING_EXCEPTION) {
3334 // management agent fails to start possibly due to
3335 // configuration problem and is responsible for printing
3336 // stack trace if appropriate. Simply exit VM.
3337 vm_exit(1);
3338 }
3339
3340 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3341 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3342 if (MemProfiling) MemProfiler::engage();
3343 StatSampler::engage();
3344 if (CheckJNICalls) JniPeriodicChecker::engage();
3345
3346 BiasedLocking::init();
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(vmSymbolHandles::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 vmSymbolHandles::shutdown_method_name(),
3584 vmSymbolHandles::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
3648 if (JDK_Version::is_jdk12x_version()) {
3649 // We are the last thread running, so check if finalizers should be run.
3650 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3651 HandleMark rm(thread);
3652 Universe::run_finalizers_on_exit();
3653 } else {
3654 // run Java level shutdown hooks
3655 thread->invoke_shutdown_hooks();
3656 }
3657
3658 before_exit(thread);
3659
3660 thread->exit(true);
3661
3662 // Stop VM thread.
3663 {
3664 // 4945125 The vm thread comes to a safepoint during exit.
3665 // GC vm_operations can get caught at the safepoint, and the
3666 // heap is unparseable if they are caught. Grab the Heap_lock
3667 // to prevent this. The GC vm_operations will not be able to
3668 // queue until after the vm thread is dead.
3669 MutexLocker ml(Heap_lock);
3670
3671 VMThread::wait_for_vm_thread_exit();
3672 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3673 VMThread::destroy();
3674 }
3675
3676 // clean up ideal graph printers
3677 #if defined(COMPILER2) && !defined(PRODUCT)
3678 IdealGraphPrinter::clean_up();
3679 #endif
3680
3681 // Now, all Java threads are gone except daemon threads. Daemon threads
3682 // running Java code or in VM are stopped by the Safepoint. However,
3683 // daemon threads executing native code are still running. But they
3684 // will be stopped at native=>Java/VM barriers. Note that we can't
3685 // simply kill or suspend them, as it is inherently deadlock-prone.
3686
3687 #ifndef PRODUCT
3688 // disable function tracing at JNI/JVM barriers
3689 TraceJNICalls = false;
3690 TraceJVMCalls = false;
3691 TraceRuntimeCalls = false;
3692 #endif
3693
3694 VM_Exit::set_vm_exited();
3695
3696 notify_vm_shutdown();
3697
3698 delete thread;
3699
3700 // exit_globals() will delete tty
3701 exit_globals();
3702
3703 return true;
3704 }
3705
3706
3707 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3708 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3709 return is_supported_jni_version(version);
3710 }
3711
3712
3713 jboolean Threads::is_supported_jni_version(jint version) {
3714 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3715 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3716 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3717 return JNI_FALSE;
3718 }
3719
3720
3721 void Threads::add(JavaThread* p, bool force_daemon) {
3722 // The threads lock must be owned at this point
3723 assert_locked_or_safepoint(Threads_lock);
3724
3725 // See the comment for this method in thread.hpp for its purpose and
3726 // why it is called here.
3727 p->initialize_queues();
3728 p->set_next(_thread_list);
3729 _thread_list = p;
3730 _number_of_threads++;
3731 oop threadObj = p->threadObj();
3732 bool daemon = true;
3733 // Bootstrapping problem: threadObj can be null for initial
3734 // JavaThread (or for threads attached via JNI)
3735 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3736 _number_of_non_daemon_threads++;
3737 daemon = false;
3738 }
3739
3740 ThreadService::add_thread(p, daemon);
3741
3742 // Possible GC point.
3743 Events::log("Thread added: " INTPTR_FORMAT, p);
3744 }
3745
3746 void Threads::remove(JavaThread* p) {
3747 // Extra scope needed for Thread_lock, so we can check
3748 // that we do not remove thread without safepoint code notice
3749 { MutexLocker ml(Threads_lock);
3750
3751 assert(includes(p), "p must be present");
3752
3753 JavaThread* current = _thread_list;
3754 JavaThread* prev = NULL;
3755
3756 while (current != p) {
3757 prev = current;
3758 current = current->next();
3759 }
3760
3761 if (prev) {
3762 prev->set_next(current->next());
3763 } else {
3764 _thread_list = p->next();
3765 }
3766 _number_of_threads--;
3767 oop threadObj = p->threadObj();
3768 bool daemon = true;
3769 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3770 _number_of_non_daemon_threads--;
3771 daemon = false;
3772
3773 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3774 // on destroy_vm will wake up.
3775 if (number_of_non_daemon_threads() == 1)
3776 Threads_lock->notify_all();
3777 }
3778 ThreadService::remove_thread(p, daemon);
3779
3780 // Make sure that safepoint code disregard this thread. This is needed since
3781 // the thread might mess around with locks after this point. This can cause it
3782 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3783 // of this thread since it is removed from the queue.
3784 p->set_terminated_value();
3785 } // unlock Threads_lock
3786
3787 // Since Events::log uses a lock, we grab it outside the Threads_lock
3788 Events::log("Thread exited: " INTPTR_FORMAT, p);
3789 }
3790
3791 // Threads_lock must be held when this is called (or must be called during a safepoint)
3792 bool Threads::includes(JavaThread* p) {
3793 assert(Threads_lock->is_locked(), "sanity check");
3794 ALL_JAVA_THREADS(q) {
3795 if (q == p ) {
3796 return true;
3797 }
3798 }
3799 return false;
3800 }
3801
3802 // Operations on the Threads list for GC. These are not explicitly locked,
3803 // but the garbage collector must provide a safe context for them to run.
3804 // In particular, these things should never be called when the Threads_lock
3805 // is held by some other thread. (Note: the Safepoint abstraction also
3806 // uses the Threads_lock to gurantee this property. It also makes sure that
3807 // all threads gets blocked when exiting or starting).
3808
3809 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3810 ALL_JAVA_THREADS(p) {
3811 p->oops_do(f, cf);
3812 }
3813 VMThread::vm_thread()->oops_do(f, cf);
3814 }
3815
3816 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3817 // Introduce a mechanism allowing parallel threads to claim threads as
3818 // root groups. Overhead should be small enough to use all the time,
3819 // even in sequential code.
3820 SharedHeap* sh = SharedHeap::heap();
3821 bool is_par = (sh->n_par_threads() > 0);
3822 int cp = SharedHeap::heap()->strong_roots_parity();
3823 ALL_JAVA_THREADS(p) {
3824 if (p->claim_oops_do(is_par, cp)) {
3825 p->oops_do(f, cf);
3826 }
3827 }
3828 VMThread* vmt = VMThread::vm_thread();
3829 if (vmt->claim_oops_do(is_par, cp))
3830 vmt->oops_do(f, cf);
3831 }
3832
3833 #ifndef SERIALGC
3834 // Used by ParallelScavenge
3835 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3836 ALL_JAVA_THREADS(p) {
3837 q->enqueue(new ThreadRootsTask(p));
3838 }
3839 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3840 }
3841
3842 // Used by Parallel Old
3843 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3844 ALL_JAVA_THREADS(p) {
3845 q->enqueue(new ThreadRootsMarkingTask(p));
3846 }
3847 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3848 }
3849 #endif // SERIALGC
3850
3851 void Threads::nmethods_do(CodeBlobClosure* cf) {
3852 ALL_JAVA_THREADS(p) {
3853 p->nmethods_do(cf);
3854 }
3855 VMThread::vm_thread()->nmethods_do(cf);
3856 }
3857
3858 void Threads::gc_epilogue() {
3859 ALL_JAVA_THREADS(p) {
3860 p->gc_epilogue();
3861 }
3862 }
3863
3864 void Threads::gc_prologue() {
3865 ALL_JAVA_THREADS(p) {
3866 p->gc_prologue();
3867 }
3868 }
3869
3870 void Threads::deoptimized_wrt_marked_nmethods() {
3871 ALL_JAVA_THREADS(p) {
3872 p->deoptimized_wrt_marked_nmethods();
3873 }
3874 }
3875
3876
3877 // Get count Java threads that are waiting to enter the specified monitor.
3878 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3879 address monitor, bool doLock) {
3880 assert(doLock || SafepointSynchronize::is_at_safepoint(),
3881 "must grab Threads_lock or be at safepoint");
3882 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3883
3884 int i = 0;
3885 {
3886 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3887 ALL_JAVA_THREADS(p) {
3888 if (p->is_Compiler_thread()) continue;
3889
3890 address pending = (address)p->current_pending_monitor();
3891 if (pending == monitor) { // found a match
3892 if (i < count) result->append(p); // save the first count matches
3893 i++;
3894 }
3895 }
3896 }
3897 return result;
3898 }
3899
3900
3901 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3902 assert(doLock ||
3903 Threads_lock->owned_by_self() ||
3904 SafepointSynchronize::is_at_safepoint(),
3905 "must grab Threads_lock or be at safepoint");
3906
3907 // NULL owner means not locked so we can skip the search
3908 if (owner == NULL) return NULL;
3909
3910 {
3911 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3912 ALL_JAVA_THREADS(p) {
3913 // first, see if owner is the address of a Java thread
3914 if (owner == (address)p) return p;
3915 }
3916 }
3917 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3918 if (UseHeavyMonitors) return NULL;
3919
3920 //
3921 // If we didn't find a matching Java thread and we didn't force use of
3922 // heavyweight monitors, then the owner is the stack address of the
3923 // Lock Word in the owning Java thread's stack.
3924 //
3925 JavaThread* the_owner = NULL;
3926 {
3927 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3928 ALL_JAVA_THREADS(q) {
3929 if (q->is_lock_owned(owner)) {
3930 the_owner = q;
3931 break;
3932 }
3933 }
3934 }
3935 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3936 return the_owner;
3937 }
3938
3939 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3940 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3941 char buf[32];
3942 st->print_cr(os::local_time_string(buf, sizeof(buf)));
3943
3944 st->print_cr("Full thread dump %s (%s %s):",
3945 Abstract_VM_Version::vm_name(),
3946 Abstract_VM_Version::vm_release(),
3947 Abstract_VM_Version::vm_info_string()
3948 );
3949 st->cr();
3950
3951 #ifndef SERIALGC
3952 // Dump concurrent locks
3953 ConcurrentLocksDump concurrent_locks;
3954 if (print_concurrent_locks) {
3955 concurrent_locks.dump_at_safepoint();
3956 }
3957 #endif // SERIALGC
3958
3959 ALL_JAVA_THREADS(p) {
3960 ResourceMark rm;
3961 p->print_on(st);
3962 if (print_stacks) {
3963 if (internal_format) {
3964 p->trace_stack();
3965 } else {
3966 p->print_stack_on(st);
3967 }
3968 }
3969 st->cr();
3970 #ifndef SERIALGC
3971 if (print_concurrent_locks) {
3972 concurrent_locks.print_locks_on(p, st);
3973 }
3974 #endif // SERIALGC
3975 }
3976
3977 VMThread::vm_thread()->print_on(st);
3978 st->cr();
3979 Universe::heap()->print_gc_threads_on(st);
3980 WatcherThread* wt = WatcherThread::watcher_thread();
3981 if (wt != NULL) wt->print_on(st);
3982 st->cr();
3983 CompileBroker::print_compiler_threads_on(st);
3984 st->flush();
3985 }
3986
3987 // Threads::print_on_error() is called by fatal error handler. It's possible
3988 // that VM is not at safepoint and/or current thread is inside signal handler.
3989 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3990 // memory (even in resource area), it might deadlock the error handler.
3991 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
3992 bool found_current = false;
3993 st->print_cr("Java Threads: ( => current thread )");
3994 ALL_JAVA_THREADS(thread) {
3995 bool is_current = (current == thread);
3996 found_current = found_current || is_current;
3997
3998 st->print("%s", is_current ? "=>" : " ");
3999
4000 st->print(PTR_FORMAT, thread);
4001 st->print(" ");
4002 thread->print_on_error(st, buf, buflen);
4003 st->cr();
4004 }
4005 st->cr();
4006
4007 st->print_cr("Other Threads:");
4008 if (VMThread::vm_thread()) {
4009 bool is_current = (current == VMThread::vm_thread());
4010 found_current = found_current || is_current;
4011 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4012
4013 st->print(PTR_FORMAT, VMThread::vm_thread());
4014 st->print(" ");
4015 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4016 st->cr();
4017 }
4018 WatcherThread* wt = WatcherThread::watcher_thread();
4019 if (wt != NULL) {
4020 bool is_current = (current == wt);
4021 found_current = found_current || is_current;
4022 st->print("%s", is_current ? "=>" : " ");
4023
4024 st->print(PTR_FORMAT, wt);
4025 st->print(" ");
4026 wt->print_on_error(st, buf, buflen);
4027 st->cr();
4028 }
4029 if (!found_current) {
4030 st->cr();
4031 st->print("=>" PTR_FORMAT " (exited) ", current);
4032 current->print_on_error(st, buf, buflen);
4033 st->cr();
4034 }
4035 }
4036
4037 // Internal SpinLock and Mutex
4038 // Based on ParkEvent
4039
4040 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4041 //
4042 // We employ SpinLocks _only for low-contention, fixed-length
4043 // short-duration critical sections where we're concerned
4044 // about native mutex_t or HotSpot Mutex:: latency.
4045 // The mux construct provides a spin-then-block mutual exclusion
4046 // mechanism.
4047 //
4048 // Testing has shown that contention on the ListLock guarding gFreeList
4049 // is common. If we implement ListLock as a simple SpinLock it's common
4050 // for the JVM to devolve to yielding with little progress. This is true
4051 // despite the fact that the critical sections protected by ListLock are
4052 // extremely short.
4053 //
4054 // TODO-FIXME: ListLock should be of type SpinLock.
4055 // We should make this a 1st-class type, integrated into the lock
4056 // hierarchy as leaf-locks. Critically, the SpinLock structure
4057 // should have sufficient padding to avoid false-sharing and excessive
4058 // cache-coherency traffic.
4059
4060
4061 typedef volatile int SpinLockT ;
4062
4063 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4064 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4065 return ; // normal fast-path return
4066 }
4067
4068 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4069 TEVENT (SpinAcquire - ctx) ;
4070 int ctr = 0 ;
4071 int Yields = 0 ;
4072 for (;;) {
4073 while (*adr != 0) {
4074 ++ctr ;
4075 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4076 if (Yields > 5) {
4077 // Consider using a simple NakedSleep() instead.
4078 // Then SpinAcquire could be called by non-JVM threads
4079 Thread::current()->_ParkEvent->park(1) ;
4080 } else {
4081 os::NakedYield() ;
4082 ++Yields ;
4083 }
4084 } else {
4085 SpinPause() ;
4086 }
4087 }
4088 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4089 }
4090 }
4091
4092 void Thread::SpinRelease (volatile int * adr) {
4093 assert (*adr != 0, "invariant") ;
4094 OrderAccess::fence() ; // guarantee at least release consistency.
4095 // Roach-motel semantics.
4096 // It's safe if subsequent LDs and STs float "up" into the critical section,
4097 // but prior LDs and STs within the critical section can't be allowed
4098 // to reorder or float past the ST that releases the lock.
4099 *adr = 0 ;
4100 }
4101
4102 // muxAcquire and muxRelease:
4103 //
4104 // * muxAcquire and muxRelease support a single-word lock-word construct.
4105 // The LSB of the word is set IFF the lock is held.
4106 // The remainder of the word points to the head of a singly-linked list
4107 // of threads blocked on the lock.
4108 //
4109 // * The current implementation of muxAcquire-muxRelease uses its own
4110 // dedicated Thread._MuxEvent instance. If we're interested in
4111 // minimizing the peak number of extant ParkEvent instances then
4112 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4113 // as certain invariants were satisfied. Specifically, care would need
4114 // to be taken with regards to consuming unpark() "permits".
4115 // A safe rule of thumb is that a thread would never call muxAcquire()
4116 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4117 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4118 // consume an unpark() permit intended for monitorenter, for instance.
4119 // One way around this would be to widen the restricted-range semaphore
4120 // implemented in park(). Another alternative would be to provide
4121 // multiple instances of the PlatformEvent() for each thread. One
4122 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4123 //
4124 // * Usage:
4125 // -- Only as leaf locks
4126 // -- for short-term locking only as muxAcquire does not perform
4127 // thread state transitions.
4128 //
4129 // Alternatives:
4130 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4131 // but with parking or spin-then-park instead of pure spinning.
4132 // * Use Taura-Oyama-Yonenzawa locks.
4133 // * It's possible to construct a 1-0 lock if we encode the lockword as
4134 // (List,LockByte). Acquire will CAS the full lockword while Release
4135 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4136 // acquiring threads use timers (ParkTimed) to detect and recover from
4137 // the stranding window. Thread/Node structures must be aligned on 256-byte
4138 // boundaries by using placement-new.
4139 // * Augment MCS with advisory back-link fields maintained with CAS().
4140 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4141 // The validity of the backlinks must be ratified before we trust the value.
4142 // If the backlinks are invalid the exiting thread must back-track through the
4143 // the forward links, which are always trustworthy.
4144 // * Add a successor indication. The LockWord is currently encoded as
4145 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4146 // to provide the usual futile-wakeup optimization.
4147 // See RTStt for details.
4148 // * Consider schedctl.sc_nopreempt to cover the critical section.
4149 //
4150
4151
4152 typedef volatile intptr_t MutexT ; // Mux Lock-word
4153 enum MuxBits { LOCKBIT = 1 } ;
4154
4155 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4156 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4157 if (w == 0) return ;
4158 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4159 return ;
4160 }
4161
4162 TEVENT (muxAcquire - Contention) ;
4163 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4164 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4165 for (;;) {
4166 int its = (os::is_MP() ? 100 : 0) + 1 ;
4167
4168 // Optional spin phase: spin-then-park strategy
4169 while (--its >= 0) {
4170 w = *Lock ;
4171 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4172 return ;
4173 }
4174 }
4175
4176 Self->reset() ;
4177 Self->OnList = intptr_t(Lock) ;
4178 // The following fence() isn't _strictly necessary as the subsequent
4179 // CAS() both serializes execution and ratifies the fetched *Lock value.
4180 OrderAccess::fence();
4181 for (;;) {
4182 w = *Lock ;
4183 if ((w & LOCKBIT) == 0) {
4184 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4185 Self->OnList = 0 ; // hygiene - allows stronger asserts
4186 return ;
4187 }
4188 continue ; // Interference -- *Lock changed -- Just retry
4189 }
4190 assert (w & LOCKBIT, "invariant") ;
4191 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4192 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4193 }
4194
4195 while (Self->OnList != 0) {
4196 Self->park() ;
4197 }
4198 }
4199 }
4200
4201 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4202 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4203 if (w == 0) return ;
4204 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4205 return ;
4206 }
4207
4208 TEVENT (muxAcquire - Contention) ;
4209 ParkEvent * ReleaseAfter = NULL ;
4210 if (ev == NULL) {
4211 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4212 }
4213 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4214 for (;;) {
4215 guarantee (ev->OnList == 0, "invariant") ;
4216 int its = (os::is_MP() ? 100 : 0) + 1 ;
4217
4218 // Optional spin phase: spin-then-park strategy
4219 while (--its >= 0) {
4220 w = *Lock ;
4221 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4222 if (ReleaseAfter != NULL) {
4223 ParkEvent::Release (ReleaseAfter) ;
4224 }
4225 return ;
4226 }
4227 }
4228
4229 ev->reset() ;
4230 ev->OnList = intptr_t(Lock) ;
4231 // The following fence() isn't _strictly necessary as the subsequent
4232 // CAS() both serializes execution and ratifies the fetched *Lock value.
4233 OrderAccess::fence();
4234 for (;;) {
4235 w = *Lock ;
4236 if ((w & LOCKBIT) == 0) {
4237 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4238 ev->OnList = 0 ;
4239 // We call ::Release while holding the outer lock, thus
4240 // artificially lengthening the critical section.
4241 // Consider deferring the ::Release() until the subsequent unlock(),
4242 // after we've dropped the outer lock.
4243 if (ReleaseAfter != NULL) {
4244 ParkEvent::Release (ReleaseAfter) ;
4245 }
4246 return ;
4247 }
4248 continue ; // Interference -- *Lock changed -- Just retry
4249 }
4250 assert (w & LOCKBIT, "invariant") ;
4251 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4252 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4253 }
4254
4255 while (ev->OnList != 0) {
4256 ev->park() ;
4257 }
4258 }
4259 }
4260
4261 // Release() must extract a successor from the list and then wake that thread.
4262 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4263 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4264 // Release() would :
4265 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4266 // (B) Extract a successor from the private list "in-hand"
4267 // (C) attempt to CAS() the residual back into *Lock over null.
4268 // If there were any newly arrived threads and the CAS() would fail.
4269 // In that case Release() would detach the RATs, re-merge the list in-hand
4270 // with the RATs and repeat as needed. Alternately, Release() might
4271 // detach and extract a successor, but then pass the residual list to the wakee.
4272 // The wakee would be responsible for reattaching and remerging before it
4273 // competed for the lock.
4274 //
4275 // Both "pop" and DMR are immune from ABA corruption -- there can be
4276 // multiple concurrent pushers, but only one popper or detacher.
4277 // This implementation pops from the head of the list. This is unfair,
4278 // but tends to provide excellent throughput as hot threads remain hot.
4279 // (We wake recently run threads first).
4280
4281 void Thread::muxRelease (volatile intptr_t * Lock) {
4282 for (;;) {
4283 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4284 assert (w & LOCKBIT, "invariant") ;
4285 if (w == LOCKBIT) return ;
4286 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4287 assert (List != NULL, "invariant") ;
4288 assert (List->OnList == intptr_t(Lock), "invariant") ;
4289 ParkEvent * nxt = List->ListNext ;
4290
4291 // The following CAS() releases the lock and pops the head element.
4292 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4293 continue ;
4294 }
4295 List->OnList = 0 ;
4296 OrderAccess::fence() ;
4297 List->unpark () ;
4298 return ;
4299 }
4300 }
4301
4302
4303 void Threads::verify() {
4304 ALL_JAVA_THREADS(p) {
4305 p->verify();
4306 }
4307 VMThread* thread = VMThread::vm_thread();
4308 if (thread != NULL) thread->verify();
4309 }