Mon, 18 Jun 2012 12:29:21 -0700
7176856: add the JRE name to the error log
Reviewed-by: coleenp, jrose, kvn, twisti
Contributed-by: Krystal Mok <sajia@taobao.com>
1 /*
2 * Copyright (c) 1997, 2012, 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 */
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 "interpreter/oopMapCache.hpp"
35 #include "jvmtifiles/jvmtiEnv.hpp"
36 #include "memory/gcLocker.inline.hpp"
37 #include "memory/oopFactory.hpp"
38 #include "memory/universe.inline.hpp"
39 #include "oops/instanceKlass.hpp"
40 #include "oops/objArrayOop.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "oops/symbol.hpp"
43 #include "prims/jvm_misc.hpp"
44 #include "prims/jvmtiExport.hpp"
45 #include "prims/jvmtiThreadState.hpp"
46 #include "prims/privilegedStack.hpp"
47 #include "runtime/aprofiler.hpp"
48 #include "runtime/arguments.hpp"
49 #include "runtime/biasedLocking.hpp"
50 #include "runtime/deoptimization.hpp"
51 #include "runtime/fprofiler.hpp"
52 #include "runtime/frame.inline.hpp"
53 #include "runtime/init.hpp"
54 #include "runtime/interfaceSupport.hpp"
55 #include "runtime/java.hpp"
56 #include "runtime/javaCalls.hpp"
57 #include "runtime/jniPeriodicChecker.hpp"
58 #include "runtime/memprofiler.hpp"
59 #include "runtime/mutexLocker.hpp"
60 #include "runtime/objectMonitor.hpp"
61 #include "runtime/osThread.hpp"
62 #include "runtime/safepoint.hpp"
63 #include "runtime/sharedRuntime.hpp"
64 #include "runtime/statSampler.hpp"
65 #include "runtime/stubRoutines.hpp"
66 #include "runtime/task.hpp"
67 #include "runtime/threadCritical.hpp"
68 #include "runtime/threadLocalStorage.hpp"
69 #include "runtime/vframe.hpp"
70 #include "runtime/vframeArray.hpp"
71 #include "runtime/vframe_hp.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "runtime/vm_operations.hpp"
74 #include "services/attachListener.hpp"
75 #include "services/management.hpp"
76 #include "services/threadService.hpp"
77 #include "trace/traceEventTypes.hpp"
78 #include "utilities/defaultStream.hpp"
79 #include "utilities/dtrace.hpp"
80 #include "utilities/events.hpp"
81 #include "utilities/preserveException.hpp"
82 #ifdef TARGET_OS_FAMILY_linux
83 # include "os_linux.inline.hpp"
84 # include "thread_linux.inline.hpp"
85 #endif
86 #ifdef TARGET_OS_FAMILY_solaris
87 # include "os_solaris.inline.hpp"
88 # include "thread_solaris.inline.hpp"
89 #endif
90 #ifdef TARGET_OS_FAMILY_windows
91 # include "os_windows.inline.hpp"
92 # include "thread_windows.inline.hpp"
93 #endif
94 #ifdef TARGET_OS_FAMILY_bsd
95 # include "os_bsd.inline.hpp"
96 # include "thread_bsd.inline.hpp"
97 #endif
98 #ifndef SERIALGC
99 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
100 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
101 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
102 #endif
103 #ifdef COMPILER1
104 #include "c1/c1_Compiler.hpp"
105 #endif
106 #ifdef COMPILER2
107 #include "opto/c2compiler.hpp"
108 #include "opto/idealGraphPrinter.hpp"
109 #endif
111 #ifdef DTRACE_ENABLED
113 // Only bother with this argument setup if dtrace is available
115 #ifndef USDT2
116 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
117 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
118 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
119 intptr_t, intptr_t, bool);
120 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
121 intptr_t, intptr_t, bool);
123 #define DTRACE_THREAD_PROBE(probe, javathread) \
124 { \
125 ResourceMark rm(this); \
126 int len = 0; \
127 const char* name = (javathread)->get_thread_name(); \
128 len = strlen(name); \
129 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
130 name, len, \
131 java_lang_Thread::thread_id((javathread)->threadObj()), \
132 (javathread)->osthread()->thread_id(), \
133 java_lang_Thread::is_daemon((javathread)->threadObj())); \
134 }
136 #else /* USDT2 */
138 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START
139 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP
141 #define DTRACE_THREAD_PROBE(probe, javathread) \
142 { \
143 ResourceMark rm(this); \
144 int len = 0; \
145 const char* name = (javathread)->get_thread_name(); \
146 len = strlen(name); \
147 HOTSPOT_THREAD_PROBE_##probe( /* probe = start, stop */ \
148 (char *) name, len, \
149 java_lang_Thread::thread_id((javathread)->threadObj()), \
150 (uintptr_t) (javathread)->osthread()->thread_id(), \
151 java_lang_Thread::is_daemon((javathread)->threadObj())); \
152 }
154 #endif /* USDT2 */
156 #else // ndef DTRACE_ENABLED
158 #define DTRACE_THREAD_PROBE(probe, javathread)
160 #endif // ndef DTRACE_ENABLED
162 // Class hierarchy
163 // - Thread
164 // - VMThread
165 // - WatcherThread
166 // - ConcurrentMarkSweepThread
167 // - JavaThread
168 // - CompilerThread
170 // ======= Thread ========
172 // Support for forcing alignment of thread objects for biased locking
173 void* Thread::operator new(size_t size) {
174 if (UseBiasedLocking) {
175 const int alignment = markOopDesc::biased_lock_alignment;
176 size_t aligned_size = size + (alignment - sizeof(intptr_t));
177 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
178 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
181 "JavaThread alignment code overflowed allocated storage");
182 if (TraceBiasedLocking) {
183 if (aligned_addr != real_malloc_addr)
184 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
185 real_malloc_addr, aligned_addr);
186 }
187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
188 return aligned_addr;
189 } else {
190 return CHeapObj::operator new(size);
191 }
192 }
194 void Thread::operator delete(void* p) {
195 if (UseBiasedLocking) {
196 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
197 CHeapObj::operator delete(real_malloc_addr);
198 } else {
199 CHeapObj::operator delete(p);
200 }
201 }
204 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
205 // JavaThread
208 Thread::Thread() {
209 // stack and get_thread
210 set_stack_base(NULL);
211 set_stack_size(0);
212 set_self_raw_id(0);
213 set_lgrp_id(-1);
215 // allocated data structures
216 set_osthread(NULL);
217 set_resource_area(new ResourceArea());
218 set_handle_area(new HandleArea(NULL));
219 set_active_handles(NULL);
220 set_free_handle_block(NULL);
221 set_last_handle_mark(NULL);
223 // This initial value ==> never claimed.
224 _oops_do_parity = 0;
226 // the handle mark links itself to last_handle_mark
227 new HandleMark(this);
229 // plain initialization
230 debug_only(_owned_locks = NULL;)
231 debug_only(_allow_allocation_count = 0;)
232 NOT_PRODUCT(_allow_safepoint_count = 0;)
233 NOT_PRODUCT(_skip_gcalot = false;)
234 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
235 _jvmti_env_iteration_count = 0;
236 set_allocated_bytes(0);
237 set_trace_buffer(NULL);
238 _vm_operation_started_count = 0;
239 _vm_operation_completed_count = 0;
240 _current_pending_monitor = NULL;
241 _current_pending_monitor_is_from_java = true;
242 _current_waiting_monitor = NULL;
243 _num_nested_signal = 0;
244 omFreeList = NULL ;
245 omFreeCount = 0 ;
246 omFreeProvision = 32 ;
247 omInUseList = NULL ;
248 omInUseCount = 0 ;
250 #ifdef ASSERT
251 _visited_for_critical_count = false;
252 #endif
254 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
255 _suspend_flags = 0;
257 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
258 _hashStateX = os::random() ;
259 _hashStateY = 842502087 ;
260 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
261 _hashStateW = 273326509 ;
263 _OnTrap = 0 ;
264 _schedctl = NULL ;
265 _Stalled = 0 ;
266 _TypeTag = 0x2BAD ;
268 // Many of the following fields are effectively final - immutable
269 // Note that nascent threads can't use the Native Monitor-Mutex
270 // construct until the _MutexEvent is initialized ...
271 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
272 // we might instead use a stack of ParkEvents that we could provision on-demand.
273 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
274 // and ::Release()
275 _ParkEvent = ParkEvent::Allocate (this) ;
276 _SleepEvent = ParkEvent::Allocate (this) ;
277 _MutexEvent = ParkEvent::Allocate (this) ;
278 _MuxEvent = ParkEvent::Allocate (this) ;
280 #ifdef CHECK_UNHANDLED_OOPS
281 if (CheckUnhandledOops) {
282 _unhandled_oops = new UnhandledOops(this);
283 }
284 #endif // CHECK_UNHANDLED_OOPS
285 #ifdef ASSERT
286 if (UseBiasedLocking) {
287 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
288 assert(this == _real_malloc_address ||
289 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
290 "bug in forced alignment of thread objects");
291 }
292 #endif /* ASSERT */
293 }
295 void Thread::initialize_thread_local_storage() {
296 // Note: Make sure this method only calls
297 // non-blocking operations. Otherwise, it might not work
298 // with the thread-startup/safepoint interaction.
300 // During Java thread startup, safepoint code should allow this
301 // method to complete because it may need to allocate memory to
302 // store information for the new thread.
304 // initialize structure dependent on thread local storage
305 ThreadLocalStorage::set_thread(this);
307 // set up any platform-specific state.
308 os::initialize_thread();
310 }
312 void Thread::record_stack_base_and_size() {
313 set_stack_base(os::current_stack_base());
314 set_stack_size(os::current_stack_size());
315 }
318 Thread::~Thread() {
319 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
320 ObjectSynchronizer::omFlush (this) ;
322 // deallocate data structures
323 delete resource_area();
324 // since the handle marks are using the handle area, we have to deallocated the root
325 // handle mark before deallocating the thread's handle area,
326 assert(last_handle_mark() != NULL, "check we have an element");
327 delete last_handle_mark();
328 assert(last_handle_mark() == NULL, "check we have reached the end");
330 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
331 // We NULL out the fields for good hygiene.
332 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
333 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
334 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
335 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
337 delete handle_area();
339 // osthread() can be NULL, if creation of thread failed.
340 if (osthread() != NULL) os::free_thread(osthread());
342 delete _SR_lock;
344 // clear thread local storage if the Thread is deleting itself
345 if (this == Thread::current()) {
346 ThreadLocalStorage::set_thread(NULL);
347 } else {
348 // In the case where we're not the current thread, invalidate all the
349 // caches in case some code tries to get the current thread or the
350 // thread that was destroyed, and gets stale information.
351 ThreadLocalStorage::invalidate_all();
352 }
353 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
354 }
356 // NOTE: dummy function for assertion purpose.
357 void Thread::run() {
358 ShouldNotReachHere();
359 }
361 #ifdef ASSERT
362 // Private method to check for dangling thread pointer
363 void check_for_dangling_thread_pointer(Thread *thread) {
364 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
365 "possibility of dangling Thread pointer");
366 }
367 #endif
370 #ifndef PRODUCT
371 // Tracing method for basic thread operations
372 void Thread::trace(const char* msg, const Thread* const thread) {
373 if (!TraceThreadEvents) return;
374 ResourceMark rm;
375 ThreadCritical tc;
376 const char *name = "non-Java thread";
377 int prio = -1;
378 if (thread->is_Java_thread()
379 && !thread->is_Compiler_thread()) {
380 // The Threads_lock must be held to get information about
381 // this thread but may not be in some situations when
382 // tracing thread events.
383 bool release_Threads_lock = false;
384 if (!Threads_lock->owned_by_self()) {
385 Threads_lock->lock();
386 release_Threads_lock = true;
387 }
388 JavaThread* jt = (JavaThread *)thread;
389 name = (char *)jt->get_thread_name();
390 oop thread_oop = jt->threadObj();
391 if (thread_oop != NULL) {
392 prio = java_lang_Thread::priority(thread_oop);
393 }
394 if (release_Threads_lock) {
395 Threads_lock->unlock();
396 }
397 }
398 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
399 }
400 #endif
403 ThreadPriority Thread::get_priority(const Thread* const thread) {
404 trace("get priority", thread);
405 ThreadPriority priority;
406 // Can return an error!
407 (void)os::get_priority(thread, priority);
408 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
409 return priority;
410 }
412 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
413 trace("set priority", thread);
414 debug_only(check_for_dangling_thread_pointer(thread);)
415 // Can return an error!
416 (void)os::set_priority(thread, priority);
417 }
420 void Thread::start(Thread* thread) {
421 trace("start", thread);
422 // Start is different from resume in that its safety is guaranteed by context or
423 // being called from a Java method synchronized on the Thread object.
424 if (!DisableStartThread) {
425 if (thread->is_Java_thread()) {
426 // Initialize the thread state to RUNNABLE before starting this thread.
427 // Can not set it after the thread started because we do not know the
428 // exact thread state at that time. It could be in MONITOR_WAIT or
429 // in SLEEPING or some other state.
430 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
431 java_lang_Thread::RUNNABLE);
432 }
433 os::start_thread(thread);
434 }
435 }
437 // Enqueue a VM_Operation to do the job for us - sometime later
438 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
439 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
440 VMThread::execute(vm_stop);
441 }
444 //
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469 //
471 // Helper class for tracing suspend wait debug bits.
472 //
473 // 0x00000100 indicates that the target thread exited before it could
474 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
475 // 0x00080000 each indicate a cancelled suspend request so they don't
476 // count as wait failures either.
477 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
479 class TraceSuspendDebugBits : public StackObj {
480 private:
481 JavaThread * jt;
482 bool is_wait;
483 bool called_by_wait; // meaningful when !is_wait
484 uint32_t * bits;
486 public:
487 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
488 uint32_t *_bits) {
489 jt = _jt;
490 is_wait = _is_wait;
491 called_by_wait = _called_by_wait;
492 bits = _bits;
493 }
495 ~TraceSuspendDebugBits() {
496 if (!is_wait) {
497 #if 1
498 // By default, don't trace bits for is_ext_suspend_completed() calls.
499 // That trace is very chatty.
500 return;
501 #else
502 if (!called_by_wait) {
503 // If tracing for is_ext_suspend_completed() is enabled, then only
504 // trace calls to it from wait_for_ext_suspend_completion()
505 return;
506 }
507 #endif
508 }
510 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
511 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
512 MutexLocker ml(Threads_lock); // needed for get_thread_name()
513 ResourceMark rm;
515 tty->print_cr(
516 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
517 jt->get_thread_name(), *bits);
519 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
520 }
521 }
522 }
523 };
524 #undef DEBUG_FALSE_BITS
527 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
533 *bits |= 0x00000001;
535 do {
536 do_trans_retry = false;
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
609 *bits |= 0x00004000;
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
641 }
642 } while (do_trans_retry);
644 *bits |= 0x00000010;
645 return false;
646 }
648 //
649 // Wait for an external suspend request to complete (or be cancelled).
650 // Returns true if the thread is externally suspended and false otherwise.
651 //
652 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
653 uint32_t *bits) {
654 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
655 false /* !called_by_wait */, bits);
657 // local flag copies to minimize SR_lock hold time
658 bool is_suspended;
659 bool pending;
660 uint32_t reset_bits;
662 // set a marker so is_ext_suspend_completed() knows we are the caller
663 *bits |= 0x00010000;
665 // We use reset_bits to reinitialize the bits value at the top of
666 // each retry loop. This allows the caller to make use of any
667 // unused bits for their own marking purposes.
668 reset_bits = *bits;
670 {
671 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
672 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
673 delay, bits);
674 pending = is_external_suspend();
675 }
676 // must release SR_lock to allow suspension to complete
678 if (!pending) {
679 // A cancelled suspend request is the only false return from
680 // is_ext_suspend_completed() that keeps us from entering the
681 // retry loop.
682 *bits |= 0x00020000;
683 return false;
684 }
686 if (is_suspended) {
687 *bits |= 0x00040000;
688 return true;
689 }
691 for (int i = 1; i <= retries; i++) {
692 *bits = reset_bits; // reinit to only track last retry
694 // We used to do an "os::yield_all(i)" call here with the intention
695 // that yielding would increase on each retry. However, the parameter
696 // is ignored on Linux which means the yield didn't scale up. Waiting
697 // on the SR_lock below provides a much more predictable scale up for
698 // the delay. It also provides a simple/direct point to check for any
699 // safepoint requests from the VMThread
701 {
702 MutexLocker ml(SR_lock());
703 // wait with safepoint check (if we're a JavaThread - the WatcherThread
704 // can also call this) and increase delay with each retry
705 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
707 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
708 delay, bits);
710 // It is possible for the external suspend request to be cancelled
711 // (by a resume) before the actual suspend operation is completed.
712 // Refresh our local copy to see if we still need to wait.
713 pending = is_external_suspend();
714 }
716 if (!pending) {
717 // A cancelled suspend request is the only false return from
718 // is_ext_suspend_completed() that keeps us from staying in the
719 // retry loop.
720 *bits |= 0x00080000;
721 return false;
722 }
724 if (is_suspended) {
725 *bits |= 0x00100000;
726 return true;
727 }
728 } // end retry loop
730 // thread did not suspend after all our retries
731 *bits |= 0x00200000;
732 return false;
733 }
735 #ifndef PRODUCT
736 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existant
740 // and we don't care that much anyway.
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif /* PRODUCT */
751 // Called by flat profiler
752 // Callers have already called wait_for_ext_suspend_completion
753 // The assertion for that is currently too complex to put here:
754 bool JavaThread::profile_last_Java_frame(frame* _fr) {
755 bool gotframe = false;
756 // self suspension saves needed state.
757 if (has_last_Java_frame() && _anchor.walkable()) {
758 *_fr = pd_last_frame();
759 gotframe = true;
760 }
761 return gotframe;
762 }
764 void Thread::interrupt(Thread* thread) {
765 trace("interrupt", thread);
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 os::interrupt(thread);
768 }
770 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
771 trace("is_interrupted", thread);
772 debug_only(check_for_dangling_thread_pointer(thread);)
773 // Note: If clear_interrupted==false, this simply fetches and
774 // returns the value of the field osthread()->interrupted().
775 return os::is_interrupted(thread, clear_interrupted);
776 }
779 // GC Support
780 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
781 jint thread_parity = _oops_do_parity;
782 if (thread_parity != strong_roots_parity) {
783 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
784 if (res == thread_parity) {
785 return true;
786 } else {
787 guarantee(res == strong_roots_parity, "Or else what?");
788 assert(SharedHeap::heap()->workers()->active_workers() > 0,
789 "Should only fail when parallel.");
790 return false;
791 }
792 }
793 assert(SharedHeap::heap()->workers()->active_workers() > 0,
794 "Should only fail when parallel.");
795 return false;
796 }
798 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
799 active_handles()->oops_do(f);
800 // Do oop for ThreadShadow
801 f->do_oop((oop*)&_pending_exception);
802 handle_area()->oops_do(f);
803 }
805 void Thread::nmethods_do(CodeBlobClosure* cf) {
806 // no nmethods in a generic thread...
807 }
809 void Thread::print_on(outputStream* st) const {
810 // get_priority assumes osthread initialized
811 if (osthread() != NULL) {
812 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
813 osthread()->print_on(st);
814 }
815 debug_only(if (WizardMode) print_owned_locks_on(st);)
816 }
818 // Thread::print_on_error() is called by fatal error handler. Don't use
819 // any lock or allocate memory.
820 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
821 if (is_VM_thread()) st->print("VMThread");
822 else if (is_Compiler_thread()) st->print("CompilerThread");
823 else if (is_Java_thread()) st->print("JavaThread");
824 else if (is_GC_task_thread()) st->print("GCTaskThread");
825 else if (is_Watcher_thread()) st->print("WatcherThread");
826 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
827 else st->print("Thread");
829 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
830 _stack_base - _stack_size, _stack_base);
832 if (osthread()) {
833 st->print(" [id=%d]", osthread()->thread_id());
834 }
835 }
837 #ifdef ASSERT
838 void Thread::print_owned_locks_on(outputStream* st) const {
839 Monitor *cur = _owned_locks;
840 if (cur == NULL) {
841 st->print(" (no locks) ");
842 } else {
843 st->print_cr(" Locks owned:");
844 while(cur) {
845 cur->print_on(st);
846 cur = cur->next();
847 }
848 }
849 }
851 static int ref_use_count = 0;
853 bool Thread::owns_locks_but_compiled_lock() const {
854 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
855 if (cur != Compile_lock) return true;
856 }
857 return false;
858 }
861 #endif
863 #ifndef PRODUCT
865 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
866 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
867 // no threads which allow_vm_block's are held
868 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
869 // Check if current thread is allowed to block at a safepoint
870 if (!(_allow_safepoint_count == 0))
871 fatal("Possible safepoint reached by thread that does not allow it");
872 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
873 fatal("LEAF method calling lock?");
874 }
876 #ifdef ASSERT
877 if (potential_vm_operation && is_Java_thread()
878 && !Universe::is_bootstrapping()) {
879 // Make sure we do not hold any locks that the VM thread also uses.
880 // This could potentially lead to deadlocks
881 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
882 // Threads_lock is special, since the safepoint synchronization will not start before this is
883 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
884 // since it is used to transfer control between JavaThreads and the VMThread
885 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
886 if ( (cur->allow_vm_block() &&
887 cur != Threads_lock &&
888 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
889 cur != VMOperationRequest_lock &&
890 cur != VMOperationQueue_lock) ||
891 cur->rank() == Mutex::special) {
892 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
893 }
894 }
895 }
897 if (GCALotAtAllSafepoints) {
898 // We could enter a safepoint here and thus have a gc
899 InterfaceSupport::check_gc_alot();
900 }
901 #endif
902 }
903 #endif
905 bool Thread::is_in_stack(address adr) const {
906 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
907 address end = os::current_stack_pointer();
908 if (stack_base() >= adr && adr >= end) return true;
910 return false;
911 }
914 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
915 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
916 // used for compilation in the future. If that change is made, the need for these methods
917 // should be revisited, and they should be removed if possible.
919 bool Thread::is_lock_owned(address adr) const {
920 return on_local_stack(adr);
921 }
923 bool Thread::set_as_starting_thread() {
924 // NOTE: this must be called inside the main thread.
925 return os::create_main_thread((JavaThread*)this);
926 }
928 static void initialize_class(Symbol* class_name, TRAPS) {
929 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
930 instanceKlass::cast(klass)->initialize(CHECK);
931 }
934 // Creates the initial ThreadGroup
935 static Handle create_initial_thread_group(TRAPS) {
936 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
937 instanceKlassHandle klass (THREAD, k);
939 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
940 {
941 JavaValue result(T_VOID);
942 JavaCalls::call_special(&result,
943 system_instance,
944 klass,
945 vmSymbols::object_initializer_name(),
946 vmSymbols::void_method_signature(),
947 CHECK_NH);
948 }
949 Universe::set_system_thread_group(system_instance());
951 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
952 {
953 JavaValue result(T_VOID);
954 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
955 JavaCalls::call_special(&result,
956 main_instance,
957 klass,
958 vmSymbols::object_initializer_name(),
959 vmSymbols::threadgroup_string_void_signature(),
960 system_instance,
961 string,
962 CHECK_NH);
963 }
964 return main_instance;
965 }
967 // Creates the initial Thread
968 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
969 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
970 instanceKlassHandle klass (THREAD, k);
971 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
973 java_lang_Thread::set_thread(thread_oop(), thread);
974 java_lang_Thread::set_priority(thread_oop(), NormPriority);
975 thread->set_threadObj(thread_oop());
977 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
979 JavaValue result(T_VOID);
980 JavaCalls::call_special(&result, thread_oop,
981 klass,
982 vmSymbols::object_initializer_name(),
983 vmSymbols::threadgroup_string_void_signature(),
984 thread_group,
985 string,
986 CHECK_NULL);
987 return thread_oop();
988 }
990 static void call_initializeSystemClass(TRAPS) {
991 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
992 instanceKlassHandle klass (THREAD, k);
994 JavaValue result(T_VOID);
995 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
996 vmSymbols::void_method_signature(), CHECK);
997 }
999 char java_runtime_name[128] = "";
1001 // extract the JRE name from sun.misc.Version.java_runtime_name
1002 static const char* get_java_runtime_name(TRAPS) {
1003 klassOop k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1004 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1005 fieldDescriptor fd;
1006 bool found = k != NULL &&
1007 instanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1008 vmSymbols::string_signature(), &fd);
1009 if (found) {
1010 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1011 if (name_oop == NULL)
1012 return NULL;
1013 const char* name = java_lang_String::as_utf8_string(name_oop,
1014 java_runtime_name,
1015 sizeof(java_runtime_name));
1016 return name;
1017 } else {
1018 return NULL;
1019 }
1020 }
1022 // General purpose hook into Java code, run once when the VM is initialized.
1023 // The Java library method itself may be changed independently from the VM.
1024 static void call_postVMInitHook(TRAPS) {
1025 klassOop k = SystemDictionary::PostVMInitHook_klass();
1026 instanceKlassHandle klass (THREAD, k);
1027 if (klass.not_null()) {
1028 JavaValue result(T_VOID);
1029 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1030 vmSymbols::void_method_signature(),
1031 CHECK);
1032 }
1033 }
1035 static void reset_vm_info_property(TRAPS) {
1036 // the vm info string
1037 ResourceMark rm(THREAD);
1038 const char *vm_info = VM_Version::vm_info_string();
1040 // java.lang.System class
1041 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1042 instanceKlassHandle klass (THREAD, k);
1044 // setProperty arguments
1045 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1046 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1048 // return value
1049 JavaValue r(T_OBJECT);
1051 // public static String setProperty(String key, String value);
1052 JavaCalls::call_static(&r,
1053 klass,
1054 vmSymbols::setProperty_name(),
1055 vmSymbols::string_string_string_signature(),
1056 key_str,
1057 value_str,
1058 CHECK);
1059 }
1062 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1063 assert(thread_group.not_null(), "thread group should be specified");
1064 assert(threadObj() == NULL, "should only create Java thread object once");
1066 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1067 instanceKlassHandle klass (THREAD, k);
1068 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1070 java_lang_Thread::set_thread(thread_oop(), this);
1071 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1072 set_threadObj(thread_oop());
1074 JavaValue result(T_VOID);
1075 if (thread_name != NULL) {
1076 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1077 // Thread gets assigned specified name and null target
1078 JavaCalls::call_special(&result,
1079 thread_oop,
1080 klass,
1081 vmSymbols::object_initializer_name(),
1082 vmSymbols::threadgroup_string_void_signature(),
1083 thread_group, // Argument 1
1084 name, // Argument 2
1085 THREAD);
1086 } else {
1087 // Thread gets assigned name "Thread-nnn" and null target
1088 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1089 JavaCalls::call_special(&result,
1090 thread_oop,
1091 klass,
1092 vmSymbols::object_initializer_name(),
1093 vmSymbols::threadgroup_runnable_void_signature(),
1094 thread_group, // Argument 1
1095 Handle(), // Argument 2
1096 THREAD);
1097 }
1100 if (daemon) {
1101 java_lang_Thread::set_daemon(thread_oop());
1102 }
1104 if (HAS_PENDING_EXCEPTION) {
1105 return;
1106 }
1108 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1109 Handle threadObj(this, this->threadObj());
1111 JavaCalls::call_special(&result,
1112 thread_group,
1113 group,
1114 vmSymbols::add_method_name(),
1115 vmSymbols::thread_void_signature(),
1116 threadObj, // Arg 1
1117 THREAD);
1120 }
1122 // NamedThread -- non-JavaThread subclasses with multiple
1123 // uniquely named instances should derive from this.
1124 NamedThread::NamedThread() : Thread() {
1125 _name = NULL;
1126 _processed_thread = NULL;
1127 }
1129 NamedThread::~NamedThread() {
1130 if (_name != NULL) {
1131 FREE_C_HEAP_ARRAY(char, _name);
1132 _name = NULL;
1133 }
1134 }
1136 void NamedThread::set_name(const char* format, ...) {
1137 guarantee(_name == NULL, "Only get to set name once.");
1138 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1139 guarantee(_name != NULL, "alloc failure");
1140 va_list ap;
1141 va_start(ap, format);
1142 jio_vsnprintf(_name, max_name_len, format, ap);
1143 va_end(ap);
1144 }
1146 // ======= WatcherThread ========
1148 // The watcher thread exists to simulate timer interrupts. It should
1149 // be replaced by an abstraction over whatever native support for
1150 // timer interrupts exists on the platform.
1152 WatcherThread* WatcherThread::_watcher_thread = NULL;
1153 volatile bool WatcherThread::_should_terminate = false;
1155 WatcherThread::WatcherThread() : Thread() {
1156 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1157 if (os::create_thread(this, os::watcher_thread)) {
1158 _watcher_thread = this;
1160 // Set the watcher thread to the highest OS priority which should not be
1161 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1162 // is created. The only normal thread using this priority is the reference
1163 // handler thread, which runs for very short intervals only.
1164 // If the VMThread's priority is not lower than the WatcherThread profiling
1165 // will be inaccurate.
1166 os::set_priority(this, MaxPriority);
1167 if (!DisableStartThread) {
1168 os::start_thread(this);
1169 }
1170 }
1171 }
1173 void WatcherThread::run() {
1174 assert(this == watcher_thread(), "just checking");
1176 this->record_stack_base_and_size();
1177 this->initialize_thread_local_storage();
1178 this->set_active_handles(JNIHandleBlock::allocate_block());
1179 while(!_should_terminate) {
1180 assert(watcher_thread() == Thread::current(), "thread consistency check");
1181 assert(watcher_thread() == this, "thread consistency check");
1183 // Calculate how long it'll be until the next PeriodicTask work
1184 // should be done, and sleep that amount of time.
1185 size_t time_to_wait = PeriodicTask::time_to_wait();
1187 // we expect this to timeout - we only ever get unparked when
1188 // we should terminate
1189 {
1190 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1192 jlong prev_time = os::javaTimeNanos();
1193 for (;;) {
1194 int res= _SleepEvent->park(time_to_wait);
1195 if (res == OS_TIMEOUT || _should_terminate)
1196 break;
1197 // spurious wakeup of some kind
1198 jlong now = os::javaTimeNanos();
1199 time_to_wait -= (now - prev_time) / 1000000;
1200 if (time_to_wait <= 0)
1201 break;
1202 prev_time = now;
1203 }
1204 }
1206 if (is_error_reported()) {
1207 // A fatal error has happened, the error handler(VMError::report_and_die)
1208 // should abort JVM after creating an error log file. However in some
1209 // rare cases, the error handler itself might deadlock. Here we try to
1210 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1211 //
1212 // This code is in WatcherThread because WatcherThread wakes up
1213 // periodically so the fatal error handler doesn't need to do anything;
1214 // also because the WatcherThread is less likely to crash than other
1215 // threads.
1217 for (;;) {
1218 if (!ShowMessageBoxOnError
1219 && (OnError == NULL || OnError[0] == '\0')
1220 && Arguments::abort_hook() == NULL) {
1221 os::sleep(this, 2 * 60 * 1000, false);
1222 fdStream err(defaultStream::output_fd());
1223 err.print_raw_cr("# [ timer expired, abort... ]");
1224 // skip atexit/vm_exit/vm_abort hooks
1225 os::die();
1226 }
1228 // Wake up 5 seconds later, the fatal handler may reset OnError or
1229 // ShowMessageBoxOnError when it is ready to abort.
1230 os::sleep(this, 5 * 1000, false);
1231 }
1232 }
1234 PeriodicTask::real_time_tick(time_to_wait);
1236 // If we have no more tasks left due to dynamic disenrollment,
1237 // shut down the thread since we don't currently support dynamic enrollment
1238 if (PeriodicTask::num_tasks() == 0) {
1239 _should_terminate = true;
1240 }
1241 }
1243 // Signal that it is terminated
1244 {
1245 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1246 _watcher_thread = NULL;
1247 Terminator_lock->notify();
1248 }
1250 // Thread destructor usually does this..
1251 ThreadLocalStorage::set_thread(NULL);
1252 }
1254 void WatcherThread::start() {
1255 if (watcher_thread() == NULL) {
1256 _should_terminate = false;
1257 // Create the single instance of WatcherThread
1258 new WatcherThread();
1259 }
1260 }
1262 void WatcherThread::stop() {
1263 // it is ok to take late safepoints here, if needed
1264 MutexLocker mu(Terminator_lock);
1265 _should_terminate = true;
1266 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1268 Thread* watcher = watcher_thread();
1269 if (watcher != NULL)
1270 watcher->_SleepEvent->unpark();
1272 while(watcher_thread() != NULL) {
1273 // This wait should make safepoint checks, wait without a timeout,
1274 // and wait as a suspend-equivalent condition.
1275 //
1276 // Note: If the FlatProfiler is running, then this thread is waiting
1277 // for the WatcherThread to terminate and the WatcherThread, via the
1278 // FlatProfiler task, is waiting for the external suspend request on
1279 // this thread to complete. wait_for_ext_suspend_completion() will
1280 // eventually timeout, but that takes time. Making this wait a
1281 // suspend-equivalent condition solves that timeout problem.
1282 //
1283 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1284 Mutex::_as_suspend_equivalent_flag);
1285 }
1286 }
1288 void WatcherThread::print_on(outputStream* st) const {
1289 st->print("\"%s\" ", name());
1290 Thread::print_on(st);
1291 st->cr();
1292 }
1294 // ======= JavaThread ========
1296 // A JavaThread is a normal Java thread
1298 void JavaThread::initialize() {
1299 // Initialize fields
1301 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1302 set_claimed_par_id(-1);
1304 set_saved_exception_pc(NULL);
1305 set_threadObj(NULL);
1306 _anchor.clear();
1307 set_entry_point(NULL);
1308 set_jni_functions(jni_functions());
1309 set_callee_target(NULL);
1310 set_vm_result(NULL);
1311 set_vm_result_2(NULL);
1312 set_vframe_array_head(NULL);
1313 set_vframe_array_last(NULL);
1314 set_deferred_locals(NULL);
1315 set_deopt_mark(NULL);
1316 set_deopt_nmethod(NULL);
1317 clear_must_deopt_id();
1318 set_monitor_chunks(NULL);
1319 set_next(NULL);
1320 set_thread_state(_thread_new);
1321 _terminated = _not_terminated;
1322 _privileged_stack_top = NULL;
1323 _array_for_gc = NULL;
1324 _suspend_equivalent = false;
1325 _in_deopt_handler = 0;
1326 _doing_unsafe_access = false;
1327 _stack_guard_state = stack_guard_unused;
1328 _exception_oop = NULL;
1329 _exception_pc = 0;
1330 _exception_handler_pc = 0;
1331 _is_method_handle_return = 0;
1332 _jvmti_thread_state= NULL;
1333 _should_post_on_exceptions_flag = JNI_FALSE;
1334 _jvmti_get_loaded_classes_closure = NULL;
1335 _interp_only_mode = 0;
1336 _special_runtime_exit_condition = _no_async_condition;
1337 _pending_async_exception = NULL;
1338 _is_compiling = false;
1339 _thread_stat = NULL;
1340 _thread_stat = new ThreadStatistics();
1341 _blocked_on_compilation = false;
1342 _jni_active_critical = 0;
1343 _do_not_unlock_if_synchronized = false;
1344 _cached_monitor_info = NULL;
1345 _parker = Parker::Allocate(this) ;
1347 #ifndef PRODUCT
1348 _jmp_ring_index = 0;
1349 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1350 record_jump(NULL, NULL, NULL, 0);
1351 }
1352 #endif /* PRODUCT */
1354 set_thread_profiler(NULL);
1355 if (FlatProfiler::is_active()) {
1356 // This is where we would decide to either give each thread it's own profiler
1357 // or use one global one from FlatProfiler,
1358 // or up to some count of the number of profiled threads, etc.
1359 ThreadProfiler* pp = new ThreadProfiler();
1360 pp->engage();
1361 set_thread_profiler(pp);
1362 }
1364 // Setup safepoint state info for this thread
1365 ThreadSafepointState::create(this);
1367 debug_only(_java_call_counter = 0);
1369 // JVMTI PopFrame support
1370 _popframe_condition = popframe_inactive;
1371 _popframe_preserved_args = NULL;
1372 _popframe_preserved_args_size = 0;
1374 pd_initialize();
1375 }
1377 #ifndef SERIALGC
1378 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1379 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1380 #endif // !SERIALGC
1382 JavaThread::JavaThread(bool is_attaching_via_jni) :
1383 Thread()
1384 #ifndef SERIALGC
1385 , _satb_mark_queue(&_satb_mark_queue_set),
1386 _dirty_card_queue(&_dirty_card_queue_set)
1387 #endif // !SERIALGC
1388 {
1389 initialize();
1390 if (is_attaching_via_jni) {
1391 _jni_attach_state = _attaching_via_jni;
1392 } else {
1393 _jni_attach_state = _not_attaching_via_jni;
1394 }
1395 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1396 }
1398 bool JavaThread::reguard_stack(address cur_sp) {
1399 if (_stack_guard_state != stack_guard_yellow_disabled) {
1400 return true; // Stack already guarded or guard pages not needed.
1401 }
1403 if (register_stack_overflow()) {
1404 // For those architectures which have separate register and
1405 // memory stacks, we must check the register stack to see if
1406 // it has overflowed.
1407 return false;
1408 }
1410 // Java code never executes within the yellow zone: the latter is only
1411 // there to provoke an exception during stack banging. If java code
1412 // is executing there, either StackShadowPages should be larger, or
1413 // some exception code in c1, c2 or the interpreter isn't unwinding
1414 // when it should.
1415 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1417 enable_stack_yellow_zone();
1418 return true;
1419 }
1421 bool JavaThread::reguard_stack(void) {
1422 return reguard_stack(os::current_stack_pointer());
1423 }
1426 void JavaThread::block_if_vm_exited() {
1427 if (_terminated == _vm_exited) {
1428 // _vm_exited is set at safepoint, and Threads_lock is never released
1429 // we will block here forever
1430 Threads_lock->lock_without_safepoint_check();
1431 ShouldNotReachHere();
1432 }
1433 }
1436 // Remove this ifdef when C1 is ported to the compiler interface.
1437 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1439 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1440 Thread()
1441 #ifndef SERIALGC
1442 , _satb_mark_queue(&_satb_mark_queue_set),
1443 _dirty_card_queue(&_dirty_card_queue_set)
1444 #endif // !SERIALGC
1445 {
1446 if (TraceThreadEvents) {
1447 tty->print_cr("creating thread %p", this);
1448 }
1449 initialize();
1450 _jni_attach_state = _not_attaching_via_jni;
1451 set_entry_point(entry_point);
1452 // Create the native thread itself.
1453 // %note runtime_23
1454 os::ThreadType thr_type = os::java_thread;
1455 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1456 os::java_thread;
1457 os::create_thread(this, thr_type, stack_sz);
1459 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1460 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1461 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1462 // the exception consists of creating the exception object & initializing it, initialization
1463 // will leave the VM via a JavaCall and then all locks must be unlocked).
1464 //
1465 // The thread is still suspended when we reach here. Thread must be explicit started
1466 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1467 // by calling Threads:add. The reason why this is not done here, is because the thread
1468 // object must be fully initialized (take a look at JVM_Start)
1469 }
1471 JavaThread::~JavaThread() {
1472 if (TraceThreadEvents) {
1473 tty->print_cr("terminate thread %p", this);
1474 }
1476 // JSR166 -- return the parker to the free list
1477 Parker::Release(_parker);
1478 _parker = NULL ;
1480 // Free any remaining previous UnrollBlock
1481 vframeArray* old_array = vframe_array_last();
1483 if (old_array != NULL) {
1484 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1485 old_array->set_unroll_block(NULL);
1486 delete old_info;
1487 delete old_array;
1488 }
1490 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1491 if (deferred != NULL) {
1492 // This can only happen if thread is destroyed before deoptimization occurs.
1493 assert(deferred->length() != 0, "empty array!");
1494 do {
1495 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1496 deferred->remove_at(0);
1497 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1498 delete dlv;
1499 } while (deferred->length() != 0);
1500 delete deferred;
1501 }
1503 // All Java related clean up happens in exit
1504 ThreadSafepointState::destroy(this);
1505 if (_thread_profiler != NULL) delete _thread_profiler;
1506 if (_thread_stat != NULL) delete _thread_stat;
1507 }
1510 // The first routine called by a new Java thread
1511 void JavaThread::run() {
1512 // initialize thread-local alloc buffer related fields
1513 this->initialize_tlab();
1515 // used to test validitity of stack trace backs
1516 this->record_base_of_stack_pointer();
1518 // Record real stack base and size.
1519 this->record_stack_base_and_size();
1521 // Initialize thread local storage; set before calling MutexLocker
1522 this->initialize_thread_local_storage();
1524 this->create_stack_guard_pages();
1526 this->cache_global_variables();
1528 // Thread is now sufficient initialized to be handled by the safepoint code as being
1529 // in the VM. Change thread state from _thread_new to _thread_in_vm
1530 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1532 assert(JavaThread::current() == this, "sanity check");
1533 assert(!Thread::current()->owns_locks(), "sanity check");
1535 DTRACE_THREAD_PROBE(start, this);
1537 // This operation might block. We call that after all safepoint checks for a new thread has
1538 // been completed.
1539 this->set_active_handles(JNIHandleBlock::allocate_block());
1541 if (JvmtiExport::should_post_thread_life()) {
1542 JvmtiExport::post_thread_start(this);
1543 }
1545 EVENT_BEGIN(TraceEventThreadStart, event);
1546 EVENT_COMMIT(event,
1547 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1549 // We call another function to do the rest so we are sure that the stack addresses used
1550 // from there will be lower than the stack base just computed
1551 thread_main_inner();
1553 // Note, thread is no longer valid at this point!
1554 }
1557 void JavaThread::thread_main_inner() {
1558 assert(JavaThread::current() == this, "sanity check");
1559 assert(this->threadObj() != NULL, "just checking");
1561 // Execute thread entry point unless this thread has a pending exception
1562 // or has been stopped before starting.
1563 // Note: Due to JVM_StopThread we can have pending exceptions already!
1564 if (!this->has_pending_exception() &&
1565 !java_lang_Thread::is_stillborn(this->threadObj())) {
1566 {
1567 ResourceMark rm(this);
1568 this->set_native_thread_name(this->get_thread_name());
1569 }
1570 HandleMark hm(this);
1571 this->entry_point()(this, this);
1572 }
1574 DTRACE_THREAD_PROBE(stop, this);
1576 this->exit(false);
1577 delete this;
1578 }
1581 static void ensure_join(JavaThread* thread) {
1582 // We do not need to grap the Threads_lock, since we are operating on ourself.
1583 Handle threadObj(thread, thread->threadObj());
1584 assert(threadObj.not_null(), "java thread object must exist");
1585 ObjectLocker lock(threadObj, thread);
1586 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1587 thread->clear_pending_exception();
1588 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1589 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1590 // Clear the native thread instance - this makes isAlive return false and allows the join()
1591 // to complete once we've done the notify_all below
1592 java_lang_Thread::set_thread(threadObj(), NULL);
1593 lock.notify_all(thread);
1594 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1595 thread->clear_pending_exception();
1596 }
1599 // For any new cleanup additions, please check to see if they need to be applied to
1600 // cleanup_failed_attach_current_thread as well.
1601 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1602 assert(this == JavaThread::current(), "thread consistency check");
1603 if (!InitializeJavaLangSystem) return;
1605 HandleMark hm(this);
1606 Handle uncaught_exception(this, this->pending_exception());
1607 this->clear_pending_exception();
1608 Handle threadObj(this, this->threadObj());
1609 assert(threadObj.not_null(), "Java thread object should be created");
1611 if (get_thread_profiler() != NULL) {
1612 get_thread_profiler()->disengage();
1613 ResourceMark rm;
1614 get_thread_profiler()->print(get_thread_name());
1615 }
1618 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1619 {
1620 EXCEPTION_MARK;
1622 CLEAR_PENDING_EXCEPTION;
1623 }
1624 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1625 // has to be fixed by a runtime query method
1626 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1627 // JSR-166: change call from from ThreadGroup.uncaughtException to
1628 // java.lang.Thread.dispatchUncaughtException
1629 if (uncaught_exception.not_null()) {
1630 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1631 {
1632 EXCEPTION_MARK;
1633 // Check if the method Thread.dispatchUncaughtException() exists. If so
1634 // call it. Otherwise we have an older library without the JSR-166 changes,
1635 // so call ThreadGroup.uncaughtException()
1636 KlassHandle recvrKlass(THREAD, threadObj->klass());
1637 CallInfo callinfo;
1638 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1639 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1640 vmSymbols::dispatchUncaughtException_name(),
1641 vmSymbols::throwable_void_signature(),
1642 KlassHandle(), false, false, THREAD);
1643 CLEAR_PENDING_EXCEPTION;
1644 methodHandle method = callinfo.selected_method();
1645 if (method.not_null()) {
1646 JavaValue result(T_VOID);
1647 JavaCalls::call_virtual(&result,
1648 threadObj, thread_klass,
1649 vmSymbols::dispatchUncaughtException_name(),
1650 vmSymbols::throwable_void_signature(),
1651 uncaught_exception,
1652 THREAD);
1653 } else {
1654 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1655 JavaValue result(T_VOID);
1656 JavaCalls::call_virtual(&result,
1657 group, thread_group,
1658 vmSymbols::uncaughtException_name(),
1659 vmSymbols::thread_throwable_void_signature(),
1660 threadObj, // Arg 1
1661 uncaught_exception, // Arg 2
1662 THREAD);
1663 }
1664 if (HAS_PENDING_EXCEPTION) {
1665 ResourceMark rm(this);
1666 jio_fprintf(defaultStream::error_stream(),
1667 "\nException: %s thrown from the UncaughtExceptionHandler"
1668 " in thread \"%s\"\n",
1669 Klass::cast(pending_exception()->klass())->external_name(),
1670 get_thread_name());
1671 CLEAR_PENDING_EXCEPTION;
1672 }
1673 }
1674 }
1676 // Called before the java thread exit since we want to read info
1677 // from java_lang_Thread object
1678 EVENT_BEGIN(TraceEventThreadEnd, event);
1679 EVENT_COMMIT(event,
1680 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1682 // Call after last event on thread
1683 EVENT_THREAD_EXIT(this);
1685 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1686 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1687 // is deprecated anyhow.
1688 { int count = 3;
1689 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1690 EXCEPTION_MARK;
1691 JavaValue result(T_VOID);
1692 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1693 JavaCalls::call_virtual(&result,
1694 threadObj, thread_klass,
1695 vmSymbols::exit_method_name(),
1696 vmSymbols::void_method_signature(),
1697 THREAD);
1698 CLEAR_PENDING_EXCEPTION;
1699 }
1700 }
1702 // notify JVMTI
1703 if (JvmtiExport::should_post_thread_life()) {
1704 JvmtiExport::post_thread_end(this);
1705 }
1707 // We have notified the agents that we are exiting, before we go on,
1708 // we must check for a pending external suspend request and honor it
1709 // in order to not surprise the thread that made the suspend request.
1710 while (true) {
1711 {
1712 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1713 if (!is_external_suspend()) {
1714 set_terminated(_thread_exiting);
1715 ThreadService::current_thread_exiting(this);
1716 break;
1717 }
1718 // Implied else:
1719 // Things get a little tricky here. We have a pending external
1720 // suspend request, but we are holding the SR_lock so we
1721 // can't just self-suspend. So we temporarily drop the lock
1722 // and then self-suspend.
1723 }
1725 ThreadBlockInVM tbivm(this);
1726 java_suspend_self();
1728 // We're done with this suspend request, but we have to loop around
1729 // and check again. Eventually we will get SR_lock without a pending
1730 // external suspend request and will be able to mark ourselves as
1731 // exiting.
1732 }
1733 // no more external suspends are allowed at this point
1734 } else {
1735 // before_exit() has already posted JVMTI THREAD_END events
1736 }
1738 // Notify waiters on thread object. This has to be done after exit() is called
1739 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1740 // group should have the destroyed bit set before waiters are notified).
1741 ensure_join(this);
1742 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1744 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1745 // held by this thread must be released. A detach operation must only
1746 // get here if there are no Java frames on the stack. Therefore, any
1747 // owned monitors at this point MUST be JNI-acquired monitors which are
1748 // pre-inflated and in the monitor cache.
1749 //
1750 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1751 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1752 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1753 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1754 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1755 }
1757 // These things needs to be done while we are still a Java Thread. Make sure that thread
1758 // is in a consistent state, in case GC happens
1759 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1761 if (active_handles() != NULL) {
1762 JNIHandleBlock* block = active_handles();
1763 set_active_handles(NULL);
1764 JNIHandleBlock::release_block(block);
1765 }
1767 if (free_handle_block() != NULL) {
1768 JNIHandleBlock* block = free_handle_block();
1769 set_free_handle_block(NULL);
1770 JNIHandleBlock::release_block(block);
1771 }
1773 // These have to be removed while this is still a valid thread.
1774 remove_stack_guard_pages();
1776 if (UseTLAB) {
1777 tlab().make_parsable(true); // retire TLAB
1778 }
1780 if (JvmtiEnv::environments_might_exist()) {
1781 JvmtiExport::cleanup_thread(this);
1782 }
1784 #ifndef SERIALGC
1785 // We must flush G1-related buffers before removing a thread from
1786 // the list of active threads.
1787 if (UseG1GC) {
1788 flush_barrier_queues();
1789 }
1790 #endif
1792 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1793 Threads::remove(this);
1794 }
1796 #ifndef SERIALGC
1797 // Flush G1-related queues.
1798 void JavaThread::flush_barrier_queues() {
1799 satb_mark_queue().flush();
1800 dirty_card_queue().flush();
1801 }
1803 void JavaThread::initialize_queues() {
1804 assert(!SafepointSynchronize::is_at_safepoint(),
1805 "we should not be at a safepoint");
1807 ObjPtrQueue& satb_queue = satb_mark_queue();
1808 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1809 // The SATB queue should have been constructed with its active
1810 // field set to false.
1811 assert(!satb_queue.is_active(), "SATB queue should not be active");
1812 assert(satb_queue.is_empty(), "SATB queue should be empty");
1813 // If we are creating the thread during a marking cycle, we should
1814 // set the active field of the SATB queue to true.
1815 if (satb_queue_set.is_active()) {
1816 satb_queue.set_active(true);
1817 }
1819 DirtyCardQueue& dirty_queue = dirty_card_queue();
1820 // The dirty card queue should have been constructed with its
1821 // active field set to true.
1822 assert(dirty_queue.is_active(), "dirty card queue should be active");
1823 }
1824 #endif // !SERIALGC
1826 void JavaThread::cleanup_failed_attach_current_thread() {
1827 if (get_thread_profiler() != NULL) {
1828 get_thread_profiler()->disengage();
1829 ResourceMark rm;
1830 get_thread_profiler()->print(get_thread_name());
1831 }
1833 if (active_handles() != NULL) {
1834 JNIHandleBlock* block = active_handles();
1835 set_active_handles(NULL);
1836 JNIHandleBlock::release_block(block);
1837 }
1839 if (free_handle_block() != NULL) {
1840 JNIHandleBlock* block = free_handle_block();
1841 set_free_handle_block(NULL);
1842 JNIHandleBlock::release_block(block);
1843 }
1845 // These have to be removed while this is still a valid thread.
1846 remove_stack_guard_pages();
1848 if (UseTLAB) {
1849 tlab().make_parsable(true); // retire TLAB, if any
1850 }
1852 #ifndef SERIALGC
1853 if (UseG1GC) {
1854 flush_barrier_queues();
1855 }
1856 #endif
1858 Threads::remove(this);
1859 delete this;
1860 }
1865 JavaThread* JavaThread::active() {
1866 Thread* thread = ThreadLocalStorage::thread();
1867 assert(thread != NULL, "just checking");
1868 if (thread->is_Java_thread()) {
1869 return (JavaThread*) thread;
1870 } else {
1871 assert(thread->is_VM_thread(), "this must be a vm thread");
1872 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1873 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1874 assert(ret->is_Java_thread(), "must be a Java thread");
1875 return ret;
1876 }
1877 }
1879 bool JavaThread::is_lock_owned(address adr) const {
1880 if (Thread::is_lock_owned(adr)) return true;
1882 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1883 if (chunk->contains(adr)) return true;
1884 }
1886 return false;
1887 }
1890 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1891 chunk->set_next(monitor_chunks());
1892 set_monitor_chunks(chunk);
1893 }
1895 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1896 guarantee(monitor_chunks() != NULL, "must be non empty");
1897 if (monitor_chunks() == chunk) {
1898 set_monitor_chunks(chunk->next());
1899 } else {
1900 MonitorChunk* prev = monitor_chunks();
1901 while (prev->next() != chunk) prev = prev->next();
1902 prev->set_next(chunk->next());
1903 }
1904 }
1906 // JVM support.
1908 // Note: this function shouldn't block if it's called in
1909 // _thread_in_native_trans state (such as from
1910 // check_special_condition_for_native_trans()).
1911 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1913 if (has_last_Java_frame() && has_async_condition()) {
1914 // If we are at a polling page safepoint (not a poll return)
1915 // then we must defer async exception because live registers
1916 // will be clobbered by the exception path. Poll return is
1917 // ok because the call we a returning from already collides
1918 // with exception handling registers and so there is no issue.
1919 // (The exception handling path kills call result registers but
1920 // this is ok since the exception kills the result anyway).
1922 if (is_at_poll_safepoint()) {
1923 // if the code we are returning to has deoptimized we must defer
1924 // the exception otherwise live registers get clobbered on the
1925 // exception path before deoptimization is able to retrieve them.
1926 //
1927 RegisterMap map(this, false);
1928 frame caller_fr = last_frame().sender(&map);
1929 assert(caller_fr.is_compiled_frame(), "what?");
1930 if (caller_fr.is_deoptimized_frame()) {
1931 if (TraceExceptions) {
1932 ResourceMark rm;
1933 tty->print_cr("deferred async exception at compiled safepoint");
1934 }
1935 return;
1936 }
1937 }
1938 }
1940 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1941 if (condition == _no_async_condition) {
1942 // Conditions have changed since has_special_runtime_exit_condition()
1943 // was called:
1944 // - if we were here only because of an external suspend request,
1945 // then that was taken care of above (or cancelled) so we are done
1946 // - if we were here because of another async request, then it has
1947 // been cleared between the has_special_runtime_exit_condition()
1948 // and now so again we are done
1949 return;
1950 }
1952 // Check for pending async. exception
1953 if (_pending_async_exception != NULL) {
1954 // Only overwrite an already pending exception, if it is not a threadDeath.
1955 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1957 // We cannot call Exceptions::_throw(...) here because we cannot block
1958 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1960 if (TraceExceptions) {
1961 ResourceMark rm;
1962 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1963 if (has_last_Java_frame() ) {
1964 frame f = last_frame();
1965 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1966 }
1967 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1968 }
1969 _pending_async_exception = NULL;
1970 clear_has_async_exception();
1971 }
1972 }
1974 if (check_unsafe_error &&
1975 condition == _async_unsafe_access_error && !has_pending_exception()) {
1976 condition = _no_async_condition; // done
1977 switch (thread_state()) {
1978 case _thread_in_vm:
1979 {
1980 JavaThread* THREAD = this;
1981 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1982 }
1983 case _thread_in_native:
1984 {
1985 ThreadInVMfromNative tiv(this);
1986 JavaThread* THREAD = this;
1987 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1988 }
1989 case _thread_in_Java:
1990 {
1991 ThreadInVMfromJava tiv(this);
1992 JavaThread* THREAD = this;
1993 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1994 }
1995 default:
1996 ShouldNotReachHere();
1997 }
1998 }
2000 assert(condition == _no_async_condition || has_pending_exception() ||
2001 (!check_unsafe_error && condition == _async_unsafe_access_error),
2002 "must have handled the async condition, if no exception");
2003 }
2005 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2006 //
2007 // Check for pending external suspend. Internal suspend requests do
2008 // not use handle_special_runtime_exit_condition().
2009 // If JNIEnv proxies are allowed, don't self-suspend if the target
2010 // thread is not the current thread. In older versions of jdbx, jdbx
2011 // threads could call into the VM with another thread's JNIEnv so we
2012 // can be here operating on behalf of a suspended thread (4432884).
2013 bool do_self_suspend = is_external_suspend_with_lock();
2014 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2015 //
2016 // Because thread is external suspended the safepoint code will count
2017 // thread as at a safepoint. This can be odd because we can be here
2018 // as _thread_in_Java which would normally transition to _thread_blocked
2019 // at a safepoint. We would like to mark the thread as _thread_blocked
2020 // before calling java_suspend_self like all other callers of it but
2021 // we must then observe proper safepoint protocol. (We can't leave
2022 // _thread_blocked with a safepoint in progress). However we can be
2023 // here as _thread_in_native_trans so we can't use a normal transition
2024 // constructor/destructor pair because they assert on that type of
2025 // transition. We could do something like:
2026 //
2027 // JavaThreadState state = thread_state();
2028 // set_thread_state(_thread_in_vm);
2029 // {
2030 // ThreadBlockInVM tbivm(this);
2031 // java_suspend_self()
2032 // }
2033 // set_thread_state(_thread_in_vm_trans);
2034 // if (safepoint) block;
2035 // set_thread_state(state);
2036 //
2037 // but that is pretty messy. Instead we just go with the way the
2038 // code has worked before and note that this is the only path to
2039 // java_suspend_self that doesn't put the thread in _thread_blocked
2040 // mode.
2042 frame_anchor()->make_walkable(this);
2043 java_suspend_self();
2045 // We might be here for reasons in addition to the self-suspend request
2046 // so check for other async requests.
2047 }
2049 if (check_asyncs) {
2050 check_and_handle_async_exceptions();
2051 }
2052 }
2054 void JavaThread::send_thread_stop(oop java_throwable) {
2055 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2056 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2057 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2059 // Do not throw asynchronous exceptions against the compiler thread
2060 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2061 if (is_Compiler_thread()) return;
2063 {
2064 // Actually throw the Throwable against the target Thread - however
2065 // only if there is no thread death exception installed already.
2066 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2067 // If the topmost frame is a runtime stub, then we are calling into
2068 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2069 // must deoptimize the caller before continuing, as the compiled exception handler table
2070 // may not be valid
2071 if (has_last_Java_frame()) {
2072 frame f = last_frame();
2073 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2074 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2075 RegisterMap reg_map(this, UseBiasedLocking);
2076 frame compiled_frame = f.sender(®_map);
2077 if (compiled_frame.can_be_deoptimized()) {
2078 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2079 }
2080 }
2081 }
2083 // Set async. pending exception in thread.
2084 set_pending_async_exception(java_throwable);
2086 if (TraceExceptions) {
2087 ResourceMark rm;
2088 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2089 }
2090 // for AbortVMOnException flag
2091 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2092 }
2093 }
2096 // Interrupt thread so it will wake up from a potential wait()
2097 Thread::interrupt(this);
2098 }
2100 // External suspension mechanism.
2101 //
2102 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2103 // to any VM_locks and it is at a transition
2104 // Self-suspension will happen on the transition out of the vm.
2105 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2106 //
2107 // Guarantees on return:
2108 // + Target thread will not execute any new bytecode (that's why we need to
2109 // force a safepoint)
2110 // + Target thread will not enter any new monitors
2111 //
2112 void JavaThread::java_suspend() {
2113 { MutexLocker mu(Threads_lock);
2114 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2115 return;
2116 }
2117 }
2119 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2120 if (!is_external_suspend()) {
2121 // a racing resume has cancelled us; bail out now
2122 return;
2123 }
2125 // suspend is done
2126 uint32_t debug_bits = 0;
2127 // Warning: is_ext_suspend_completed() may temporarily drop the
2128 // SR_lock to allow the thread to reach a stable thread state if
2129 // it is currently in a transient thread state.
2130 if (is_ext_suspend_completed(false /* !called_by_wait */,
2131 SuspendRetryDelay, &debug_bits) ) {
2132 return;
2133 }
2134 }
2136 VM_ForceSafepoint vm_suspend;
2137 VMThread::execute(&vm_suspend);
2138 }
2140 // Part II of external suspension.
2141 // A JavaThread self suspends when it detects a pending external suspend
2142 // request. This is usually on transitions. It is also done in places
2143 // where continuing to the next transition would surprise the caller,
2144 // e.g., monitor entry.
2145 //
2146 // Returns the number of times that the thread self-suspended.
2147 //
2148 // Note: DO NOT call java_suspend_self() when you just want to block current
2149 // thread. java_suspend_self() is the second stage of cooperative
2150 // suspension for external suspend requests and should only be used
2151 // to complete an external suspend request.
2152 //
2153 int JavaThread::java_suspend_self() {
2154 int ret = 0;
2156 // we are in the process of exiting so don't suspend
2157 if (is_exiting()) {
2158 clear_external_suspend();
2159 return ret;
2160 }
2162 assert(_anchor.walkable() ||
2163 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2164 "must have walkable stack");
2166 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2168 assert(!this->is_ext_suspended(),
2169 "a thread trying to self-suspend should not already be suspended");
2171 if (this->is_suspend_equivalent()) {
2172 // If we are self-suspending as a result of the lifting of a
2173 // suspend equivalent condition, then the suspend_equivalent
2174 // flag is not cleared until we set the ext_suspended flag so
2175 // that wait_for_ext_suspend_completion() returns consistent
2176 // results.
2177 this->clear_suspend_equivalent();
2178 }
2180 // A racing resume may have cancelled us before we grabbed SR_lock
2181 // above. Or another external suspend request could be waiting for us
2182 // by the time we return from SR_lock()->wait(). The thread
2183 // that requested the suspension may already be trying to walk our
2184 // stack and if we return now, we can change the stack out from under
2185 // it. This would be a "bad thing (TM)" and cause the stack walker
2186 // to crash. We stay self-suspended until there are no more pending
2187 // external suspend requests.
2188 while (is_external_suspend()) {
2189 ret++;
2190 this->set_ext_suspended();
2192 // _ext_suspended flag is cleared by java_resume()
2193 while (is_ext_suspended()) {
2194 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2195 }
2196 }
2198 return ret;
2199 }
2201 #ifdef ASSERT
2202 // verify the JavaThread has not yet been published in the Threads::list, and
2203 // hence doesn't need protection from concurrent access at this stage
2204 void JavaThread::verify_not_published() {
2205 if (!Threads_lock->owned_by_self()) {
2206 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2207 assert( !Threads::includes(this),
2208 "java thread shouldn't have been published yet!");
2209 }
2210 else {
2211 assert( !Threads::includes(this),
2212 "java thread shouldn't have been published yet!");
2213 }
2214 }
2215 #endif
2217 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2218 // progress or when _suspend_flags is non-zero.
2219 // Current thread needs to self-suspend if there is a suspend request and/or
2220 // block if a safepoint is in progress.
2221 // Async exception ISN'T checked.
2222 // Note only the ThreadInVMfromNative transition can call this function
2223 // directly and when thread state is _thread_in_native_trans
2224 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2225 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2227 JavaThread *curJT = JavaThread::current();
2228 bool do_self_suspend = thread->is_external_suspend();
2230 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2232 // If JNIEnv proxies are allowed, don't self-suspend if the target
2233 // thread is not the current thread. In older versions of jdbx, jdbx
2234 // threads could call into the VM with another thread's JNIEnv so we
2235 // can be here operating on behalf of a suspended thread (4432884).
2236 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2237 JavaThreadState state = thread->thread_state();
2239 // We mark this thread_blocked state as a suspend-equivalent so
2240 // that a caller to is_ext_suspend_completed() won't be confused.
2241 // The suspend-equivalent state is cleared by java_suspend_self().
2242 thread->set_suspend_equivalent();
2244 // If the safepoint code sees the _thread_in_native_trans state, it will
2245 // wait until the thread changes to other thread state. There is no
2246 // guarantee on how soon we can obtain the SR_lock and complete the
2247 // self-suspend request. It would be a bad idea to let safepoint wait for
2248 // too long. Temporarily change the state to _thread_blocked to
2249 // let the VM thread know that this thread is ready for GC. The problem
2250 // of changing thread state is that safepoint could happen just after
2251 // java_suspend_self() returns after being resumed, and VM thread will
2252 // see the _thread_blocked state. We must check for safepoint
2253 // after restoring the state and make sure we won't leave while a safepoint
2254 // is in progress.
2255 thread->set_thread_state(_thread_blocked);
2256 thread->java_suspend_self();
2257 thread->set_thread_state(state);
2258 // Make sure new state is seen by VM thread
2259 if (os::is_MP()) {
2260 if (UseMembar) {
2261 // Force a fence between the write above and read below
2262 OrderAccess::fence();
2263 } else {
2264 // Must use this rather than serialization page in particular on Windows
2265 InterfaceSupport::serialize_memory(thread);
2266 }
2267 }
2268 }
2270 if (SafepointSynchronize::do_call_back()) {
2271 // If we are safepointing, then block the caller which may not be
2272 // the same as the target thread (see above).
2273 SafepointSynchronize::block(curJT);
2274 }
2276 if (thread->is_deopt_suspend()) {
2277 thread->clear_deopt_suspend();
2278 RegisterMap map(thread, false);
2279 frame f = thread->last_frame();
2280 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2281 f = f.sender(&map);
2282 }
2283 if (f.id() == thread->must_deopt_id()) {
2284 thread->clear_must_deopt_id();
2285 f.deoptimize(thread);
2286 } else {
2287 fatal("missed deoptimization!");
2288 }
2289 }
2290 }
2292 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2293 // progress or when _suspend_flags is non-zero.
2294 // Current thread needs to self-suspend if there is a suspend request and/or
2295 // block if a safepoint is in progress.
2296 // Also check for pending async exception (not including unsafe access error).
2297 // Note only the native==>VM/Java barriers can call this function and when
2298 // thread state is _thread_in_native_trans.
2299 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2300 check_safepoint_and_suspend_for_native_trans(thread);
2302 if (thread->has_async_exception()) {
2303 // We are in _thread_in_native_trans state, don't handle unsafe
2304 // access error since that may block.
2305 thread->check_and_handle_async_exceptions(false);
2306 }
2307 }
2309 // This is a variant of the normal
2310 // check_special_condition_for_native_trans with slightly different
2311 // semantics for use by critical native wrappers. It does all the
2312 // normal checks but also performs the transition back into
2313 // thread_in_Java state. This is required so that critical natives
2314 // can potentially block and perform a GC if they are the last thread
2315 // exiting the GC_locker.
2316 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2317 check_special_condition_for_native_trans(thread);
2319 // Finish the transition
2320 thread->set_thread_state(_thread_in_Java);
2322 if (thread->do_critical_native_unlock()) {
2323 ThreadInVMfromJavaNoAsyncException tiv(thread);
2324 GC_locker::unlock_critical(thread);
2325 thread->clear_critical_native_unlock();
2326 }
2327 }
2329 // We need to guarantee the Threads_lock here, since resumes are not
2330 // allowed during safepoint synchronization
2331 // Can only resume from an external suspension
2332 void JavaThread::java_resume() {
2333 assert_locked_or_safepoint(Threads_lock);
2335 // Sanity check: thread is gone, has started exiting or the thread
2336 // was not externally suspended.
2337 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2338 return;
2339 }
2341 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2343 clear_external_suspend();
2345 if (is_ext_suspended()) {
2346 clear_ext_suspended();
2347 SR_lock()->notify_all();
2348 }
2349 }
2351 void JavaThread::create_stack_guard_pages() {
2352 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2353 address low_addr = stack_base() - stack_size();
2354 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2356 int allocate = os::allocate_stack_guard_pages();
2357 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2359 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2360 warning("Attempt to allocate stack guard pages failed.");
2361 return;
2362 }
2364 if (os::guard_memory((char *) low_addr, len)) {
2365 _stack_guard_state = stack_guard_enabled;
2366 } else {
2367 warning("Attempt to protect stack guard pages failed.");
2368 if (os::uncommit_memory((char *) low_addr, len)) {
2369 warning("Attempt to deallocate stack guard pages failed.");
2370 }
2371 }
2372 }
2374 void JavaThread::remove_stack_guard_pages() {
2375 if (_stack_guard_state == stack_guard_unused) return;
2376 address low_addr = stack_base() - stack_size();
2377 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2379 if (os::allocate_stack_guard_pages()) {
2380 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2381 _stack_guard_state = stack_guard_unused;
2382 } else {
2383 warning("Attempt to deallocate stack guard pages failed.");
2384 }
2385 } else {
2386 if (_stack_guard_state == stack_guard_unused) return;
2387 if (os::unguard_memory((char *) low_addr, len)) {
2388 _stack_guard_state = stack_guard_unused;
2389 } else {
2390 warning("Attempt to unprotect stack guard pages failed.");
2391 }
2392 }
2393 }
2395 void JavaThread::enable_stack_yellow_zone() {
2396 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2397 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2399 // The base notation is from the stacks point of view, growing downward.
2400 // We need to adjust it to work correctly with guard_memory()
2401 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2403 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2404 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2406 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2407 _stack_guard_state = stack_guard_enabled;
2408 } else {
2409 warning("Attempt to guard stack yellow zone failed.");
2410 }
2411 enable_register_stack_guard();
2412 }
2414 void JavaThread::disable_stack_yellow_zone() {
2415 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2416 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2418 // Simply return if called for a thread that does not use guard pages.
2419 if (_stack_guard_state == stack_guard_unused) return;
2421 // The base notation is from the stacks point of view, growing downward.
2422 // We need to adjust it to work correctly with guard_memory()
2423 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2425 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2426 _stack_guard_state = stack_guard_yellow_disabled;
2427 } else {
2428 warning("Attempt to unguard stack yellow zone failed.");
2429 }
2430 disable_register_stack_guard();
2431 }
2433 void JavaThread::enable_stack_red_zone() {
2434 // The base notation is from the stacks point of view, growing downward.
2435 // We need to adjust it to work correctly with guard_memory()
2436 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2437 address base = stack_red_zone_base() - stack_red_zone_size();
2439 guarantee(base < stack_base(),"Error calculating stack red zone");
2440 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2442 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2443 warning("Attempt to guard stack red zone failed.");
2444 }
2445 }
2447 void JavaThread::disable_stack_red_zone() {
2448 // The base notation is from the stacks point of view, growing downward.
2449 // We need to adjust it to work correctly with guard_memory()
2450 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2451 address base = stack_red_zone_base() - stack_red_zone_size();
2452 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2453 warning("Attempt to unguard stack red zone failed.");
2454 }
2455 }
2457 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2458 // ignore is there is no stack
2459 if (!has_last_Java_frame()) return;
2460 // traverse the stack frames. Starts from top frame.
2461 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2462 frame* fr = fst.current();
2463 f(fr, fst.register_map());
2464 }
2465 }
2468 #ifndef PRODUCT
2469 // Deoptimization
2470 // Function for testing deoptimization
2471 void JavaThread::deoptimize() {
2472 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2473 StackFrameStream fst(this, UseBiasedLocking);
2474 bool deopt = false; // Dump stack only if a deopt actually happens.
2475 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2476 // Iterate over all frames in the thread and deoptimize
2477 for(; !fst.is_done(); fst.next()) {
2478 if(fst.current()->can_be_deoptimized()) {
2480 if (only_at) {
2481 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2482 // consists of comma or carriage return separated numbers so
2483 // search for the current bci in that string.
2484 address pc = fst.current()->pc();
2485 nmethod* nm = (nmethod*) fst.current()->cb();
2486 ScopeDesc* sd = nm->scope_desc_at( pc);
2487 char buffer[8];
2488 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2489 size_t len = strlen(buffer);
2490 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2491 while (found != NULL) {
2492 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2493 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2494 // Check that the bci found is bracketed by terminators.
2495 break;
2496 }
2497 found = strstr(found + 1, buffer);
2498 }
2499 if (!found) {
2500 continue;
2501 }
2502 }
2504 if (DebugDeoptimization && !deopt) {
2505 deopt = true; // One-time only print before deopt
2506 tty->print_cr("[BEFORE Deoptimization]");
2507 trace_frames();
2508 trace_stack();
2509 }
2510 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2511 }
2512 }
2514 if (DebugDeoptimization && deopt) {
2515 tty->print_cr("[AFTER Deoptimization]");
2516 trace_frames();
2517 }
2518 }
2521 // Make zombies
2522 void JavaThread::make_zombies() {
2523 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2524 if (fst.current()->can_be_deoptimized()) {
2525 // it is a Java nmethod
2526 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2527 nm->make_not_entrant();
2528 }
2529 }
2530 }
2531 #endif // PRODUCT
2534 void JavaThread::deoptimized_wrt_marked_nmethods() {
2535 if (!has_last_Java_frame()) return;
2536 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2537 StackFrameStream fst(this, UseBiasedLocking);
2538 for(; !fst.is_done(); fst.next()) {
2539 if (fst.current()->should_be_deoptimized()) {
2540 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2541 }
2542 }
2543 }
2546 // GC support
2547 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2549 void JavaThread::gc_epilogue() {
2550 frames_do(frame_gc_epilogue);
2551 }
2554 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2556 void JavaThread::gc_prologue() {
2557 frames_do(frame_gc_prologue);
2558 }
2560 // If the caller is a NamedThread, then remember, in the current scope,
2561 // the given JavaThread in its _processed_thread field.
2562 class RememberProcessedThread: public StackObj {
2563 NamedThread* _cur_thr;
2564 public:
2565 RememberProcessedThread(JavaThread* jthr) {
2566 Thread* thread = Thread::current();
2567 if (thread->is_Named_thread()) {
2568 _cur_thr = (NamedThread *)thread;
2569 _cur_thr->set_processed_thread(jthr);
2570 } else {
2571 _cur_thr = NULL;
2572 }
2573 }
2575 ~RememberProcessedThread() {
2576 if (_cur_thr) {
2577 _cur_thr->set_processed_thread(NULL);
2578 }
2579 }
2580 };
2582 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2583 // Verify that the deferred card marks have been flushed.
2584 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2586 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2587 // since there may be more than one thread using each ThreadProfiler.
2589 // Traverse the GCHandles
2590 Thread::oops_do(f, cf);
2592 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2593 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2595 if (has_last_Java_frame()) {
2596 // Record JavaThread to GC thread
2597 RememberProcessedThread rpt(this);
2599 // Traverse the privileged stack
2600 if (_privileged_stack_top != NULL) {
2601 _privileged_stack_top->oops_do(f);
2602 }
2604 // traverse the registered growable array
2605 if (_array_for_gc != NULL) {
2606 for (int index = 0; index < _array_for_gc->length(); index++) {
2607 f->do_oop(_array_for_gc->adr_at(index));
2608 }
2609 }
2611 // Traverse the monitor chunks
2612 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2613 chunk->oops_do(f);
2614 }
2616 // Traverse the execution stack
2617 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2618 fst.current()->oops_do(f, cf, fst.register_map());
2619 }
2620 }
2622 // callee_target is never live across a gc point so NULL it here should
2623 // it still contain a methdOop.
2625 set_callee_target(NULL);
2627 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2628 // If we have deferred set_locals there might be oops waiting to be
2629 // written
2630 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2631 if (list != NULL) {
2632 for (int i = 0; i < list->length(); i++) {
2633 list->at(i)->oops_do(f);
2634 }
2635 }
2637 // Traverse instance variables at the end since the GC may be moving things
2638 // around using this function
2639 f->do_oop((oop*) &_threadObj);
2640 f->do_oop((oop*) &_vm_result);
2641 f->do_oop((oop*) &_vm_result_2);
2642 f->do_oop((oop*) &_exception_oop);
2643 f->do_oop((oop*) &_pending_async_exception);
2645 if (jvmti_thread_state() != NULL) {
2646 jvmti_thread_state()->oops_do(f);
2647 }
2648 }
2650 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2651 Thread::nmethods_do(cf); // (super method is a no-op)
2653 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2654 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2656 if (has_last_Java_frame()) {
2657 // Traverse the execution stack
2658 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2659 fst.current()->nmethods_do(cf);
2660 }
2661 }
2662 }
2664 // Printing
2665 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2666 switch (_thread_state) {
2667 case _thread_uninitialized: return "_thread_uninitialized";
2668 case _thread_new: return "_thread_new";
2669 case _thread_new_trans: return "_thread_new_trans";
2670 case _thread_in_native: return "_thread_in_native";
2671 case _thread_in_native_trans: return "_thread_in_native_trans";
2672 case _thread_in_vm: return "_thread_in_vm";
2673 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2674 case _thread_in_Java: return "_thread_in_Java";
2675 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2676 case _thread_blocked: return "_thread_blocked";
2677 case _thread_blocked_trans: return "_thread_blocked_trans";
2678 default: return "unknown thread state";
2679 }
2680 }
2682 #ifndef PRODUCT
2683 void JavaThread::print_thread_state_on(outputStream *st) const {
2684 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2685 };
2686 void JavaThread::print_thread_state() const {
2687 print_thread_state_on(tty);
2688 };
2689 #endif // PRODUCT
2691 // Called by Threads::print() for VM_PrintThreads operation
2692 void JavaThread::print_on(outputStream *st) const {
2693 st->print("\"%s\" ", get_thread_name());
2694 oop thread_oop = threadObj();
2695 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2696 Thread::print_on(st);
2697 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2698 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2699 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2700 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2701 }
2702 #ifndef PRODUCT
2703 print_thread_state_on(st);
2704 _safepoint_state->print_on(st);
2705 #endif // PRODUCT
2706 }
2708 // Called by fatal error handler. The difference between this and
2709 // JavaThread::print() is that we can't grab lock or allocate memory.
2710 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2711 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2712 oop thread_obj = threadObj();
2713 if (thread_obj != NULL) {
2714 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2715 }
2716 st->print(" [");
2717 st->print("%s", _get_thread_state_name(_thread_state));
2718 if (osthread()) {
2719 st->print(", id=%d", osthread()->thread_id());
2720 }
2721 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2722 _stack_base - _stack_size, _stack_base);
2723 st->print("]");
2724 return;
2725 }
2727 // Verification
2729 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2731 void JavaThread::verify() {
2732 // Verify oops in the thread.
2733 oops_do(&VerifyOopClosure::verify_oop, NULL);
2735 // Verify the stack frames.
2736 frames_do(frame_verify);
2737 }
2739 // CR 6300358 (sub-CR 2137150)
2740 // Most callers of this method assume that it can't return NULL but a
2741 // thread may not have a name whilst it is in the process of attaching to
2742 // the VM - see CR 6412693, and there are places where a JavaThread can be
2743 // seen prior to having it's threadObj set (eg JNI attaching threads and
2744 // if vm exit occurs during initialization). These cases can all be accounted
2745 // for such that this method never returns NULL.
2746 const char* JavaThread::get_thread_name() const {
2747 #ifdef ASSERT
2748 // early safepoints can hit while current thread does not yet have TLS
2749 if (!SafepointSynchronize::is_at_safepoint()) {
2750 Thread *cur = Thread::current();
2751 if (!(cur->is_Java_thread() && cur == this)) {
2752 // Current JavaThreads are allowed to get their own name without
2753 // the Threads_lock.
2754 assert_locked_or_safepoint(Threads_lock);
2755 }
2756 }
2757 #endif // ASSERT
2758 return get_thread_name_string();
2759 }
2761 // Returns a non-NULL representation of this thread's name, or a suitable
2762 // descriptive string if there is no set name
2763 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2764 const char* name_str;
2765 oop thread_obj = threadObj();
2766 if (thread_obj != NULL) {
2767 typeArrayOop name = java_lang_Thread::name(thread_obj);
2768 if (name != NULL) {
2769 if (buf == NULL) {
2770 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2771 }
2772 else {
2773 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2774 }
2775 }
2776 else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2777 name_str = "<no-name - thread is attaching>";
2778 }
2779 else {
2780 name_str = Thread::name();
2781 }
2782 }
2783 else {
2784 name_str = Thread::name();
2785 }
2786 assert(name_str != NULL, "unexpected NULL thread name");
2787 return name_str;
2788 }
2791 const char* JavaThread::get_threadgroup_name() const {
2792 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2793 oop thread_obj = threadObj();
2794 if (thread_obj != NULL) {
2795 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2796 if (thread_group != NULL) {
2797 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2798 // ThreadGroup.name can be null
2799 if (name != NULL) {
2800 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2801 return str;
2802 }
2803 }
2804 }
2805 return NULL;
2806 }
2808 const char* JavaThread::get_parent_name() const {
2809 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2810 oop thread_obj = threadObj();
2811 if (thread_obj != NULL) {
2812 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2813 if (thread_group != NULL) {
2814 oop parent = java_lang_ThreadGroup::parent(thread_group);
2815 if (parent != NULL) {
2816 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2817 // ThreadGroup.name can be null
2818 if (name != NULL) {
2819 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2820 return str;
2821 }
2822 }
2823 }
2824 }
2825 return NULL;
2826 }
2828 ThreadPriority JavaThread::java_priority() const {
2829 oop thr_oop = threadObj();
2830 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2831 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2832 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2833 return priority;
2834 }
2836 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2838 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2839 // Link Java Thread object <-> C++ Thread
2841 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2842 // and put it into a new Handle. The Handle "thread_oop" can then
2843 // be used to pass the C++ thread object to other methods.
2845 // Set the Java level thread object (jthread) field of the
2846 // new thread (a JavaThread *) to C++ thread object using the
2847 // "thread_oop" handle.
2849 // Set the thread field (a JavaThread *) of the
2850 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2852 Handle thread_oop(Thread::current(),
2853 JNIHandles::resolve_non_null(jni_thread));
2854 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2855 "must be initialized");
2856 set_threadObj(thread_oop());
2857 java_lang_Thread::set_thread(thread_oop(), this);
2859 if (prio == NoPriority) {
2860 prio = java_lang_Thread::priority(thread_oop());
2861 assert(prio != NoPriority, "A valid priority should be present");
2862 }
2864 // Push the Java priority down to the native thread; needs Threads_lock
2865 Thread::set_priority(this, prio);
2867 // Add the new thread to the Threads list and set it in motion.
2868 // We must have threads lock in order to call Threads::add.
2869 // It is crucial that we do not block before the thread is
2870 // added to the Threads list for if a GC happens, then the java_thread oop
2871 // will not be visited by GC.
2872 Threads::add(this);
2873 }
2875 oop JavaThread::current_park_blocker() {
2876 // Support for JSR-166 locks
2877 oop thread_oop = threadObj();
2878 if (thread_oop != NULL &&
2879 JDK_Version::current().supports_thread_park_blocker()) {
2880 return java_lang_Thread::park_blocker(thread_oop);
2881 }
2882 return NULL;
2883 }
2886 void JavaThread::print_stack_on(outputStream* st) {
2887 if (!has_last_Java_frame()) return;
2888 ResourceMark rm;
2889 HandleMark hm;
2891 RegisterMap reg_map(this);
2892 vframe* start_vf = last_java_vframe(®_map);
2893 int count = 0;
2894 for (vframe* f = start_vf; f; f = f->sender() ) {
2895 if (f->is_java_frame()) {
2896 javaVFrame* jvf = javaVFrame::cast(f);
2897 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2899 // Print out lock information
2900 if (JavaMonitorsInStackTrace) {
2901 jvf->print_lock_info_on(st, count);
2902 }
2903 } else {
2904 // Ignore non-Java frames
2905 }
2907 // Bail-out case for too deep stacks
2908 count++;
2909 if (MaxJavaStackTraceDepth == count) return;
2910 }
2911 }
2914 // JVMTI PopFrame support
2915 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2916 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2917 if (in_bytes(size_in_bytes) != 0) {
2918 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2919 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2920 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2921 }
2922 }
2924 void* JavaThread::popframe_preserved_args() {
2925 return _popframe_preserved_args;
2926 }
2928 ByteSize JavaThread::popframe_preserved_args_size() {
2929 return in_ByteSize(_popframe_preserved_args_size);
2930 }
2932 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2933 int sz = in_bytes(popframe_preserved_args_size());
2934 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2935 return in_WordSize(sz / wordSize);
2936 }
2938 void JavaThread::popframe_free_preserved_args() {
2939 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2940 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2941 _popframe_preserved_args = NULL;
2942 _popframe_preserved_args_size = 0;
2943 }
2945 #ifndef PRODUCT
2947 void JavaThread::trace_frames() {
2948 tty->print_cr("[Describe stack]");
2949 int frame_no = 1;
2950 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2951 tty->print(" %d. ", frame_no++);
2952 fst.current()->print_value_on(tty,this);
2953 tty->cr();
2954 }
2955 }
2957 class PrintAndVerifyOopClosure: public OopClosure {
2958 protected:
2959 template <class T> inline void do_oop_work(T* p) {
2960 oop obj = oopDesc::load_decode_heap_oop(p);
2961 if (obj == NULL) return;
2962 tty->print(INTPTR_FORMAT ": ", p);
2963 if (obj->is_oop_or_null()) {
2964 if (obj->is_objArray()) {
2965 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
2966 } else {
2967 obj->print();
2968 }
2969 } else {
2970 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
2971 }
2972 tty->cr();
2973 }
2974 public:
2975 virtual void do_oop(oop* p) { do_oop_work(p); }
2976 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2977 };
2980 static void oops_print(frame* f, const RegisterMap *map) {
2981 PrintAndVerifyOopClosure print;
2982 f->print_value();
2983 f->oops_do(&print, NULL, (RegisterMap*)map);
2984 }
2986 // Print our all the locations that contain oops and whether they are
2987 // valid or not. This useful when trying to find the oldest frame
2988 // where an oop has gone bad since the frame walk is from youngest to
2989 // oldest.
2990 void JavaThread::trace_oops() {
2991 tty->print_cr("[Trace oops]");
2992 frames_do(oops_print);
2993 }
2996 #ifdef ASSERT
2997 // Print or validate the layout of stack frames
2998 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2999 ResourceMark rm;
3000 PRESERVE_EXCEPTION_MARK;
3001 FrameValues values;
3002 int frame_no = 0;
3003 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3004 fst.current()->describe(values, ++frame_no);
3005 if (depth == frame_no) break;
3006 }
3007 if (validate_only) {
3008 values.validate();
3009 } else {
3010 tty->print_cr("[Describe stack layout]");
3011 values.print(this);
3012 }
3013 }
3014 #endif
3016 void JavaThread::trace_stack_from(vframe* start_vf) {
3017 ResourceMark rm;
3018 int vframe_no = 1;
3019 for (vframe* f = start_vf; f; f = f->sender() ) {
3020 if (f->is_java_frame()) {
3021 javaVFrame::cast(f)->print_activation(vframe_no++);
3022 } else {
3023 f->print();
3024 }
3025 if (vframe_no > StackPrintLimit) {
3026 tty->print_cr("...<more frames>...");
3027 return;
3028 }
3029 }
3030 }
3033 void JavaThread::trace_stack() {
3034 if (!has_last_Java_frame()) return;
3035 ResourceMark rm;
3036 HandleMark hm;
3037 RegisterMap reg_map(this);
3038 trace_stack_from(last_java_vframe(®_map));
3039 }
3042 #endif // PRODUCT
3045 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3046 assert(reg_map != NULL, "a map must be given");
3047 frame f = last_frame();
3048 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3049 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3050 }
3051 return NULL;
3052 }
3055 klassOop JavaThread::security_get_caller_class(int depth) {
3056 vframeStream vfst(this);
3057 vfst.security_get_caller_frame(depth);
3058 if (!vfst.at_end()) {
3059 return vfst.method()->method_holder();
3060 }
3061 return NULL;
3062 }
3064 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3065 assert(thread->is_Compiler_thread(), "must be compiler thread");
3066 CompileBroker::compiler_thread_loop();
3067 }
3069 // Create a CompilerThread
3070 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3071 : JavaThread(&compiler_thread_entry) {
3072 _env = NULL;
3073 _log = NULL;
3074 _task = NULL;
3075 _queue = queue;
3076 _counters = counters;
3077 _buffer_blob = NULL;
3078 _scanned_nmethod = NULL;
3080 #ifndef PRODUCT
3081 _ideal_graph_printer = NULL;
3082 #endif
3083 }
3085 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3086 JavaThread::oops_do(f, cf);
3087 if (_scanned_nmethod != NULL && cf != NULL) {
3088 // Safepoints can occur when the sweeper is scanning an nmethod so
3089 // process it here to make sure it isn't unloaded in the middle of
3090 // a scan.
3091 cf->do_code_blob(_scanned_nmethod);
3092 }
3093 }
3095 // ======= Threads ========
3097 // The Threads class links together all active threads, and provides
3098 // operations over all threads. It is protected by its own Mutex
3099 // lock, which is also used in other contexts to protect thread
3100 // operations from having the thread being operated on from exiting
3101 // and going away unexpectedly (e.g., safepoint synchronization)
3103 JavaThread* Threads::_thread_list = NULL;
3104 int Threads::_number_of_threads = 0;
3105 int Threads::_number_of_non_daemon_threads = 0;
3106 int Threads::_return_code = 0;
3107 size_t JavaThread::_stack_size_at_create = 0;
3109 // All JavaThreads
3110 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3112 void os_stream();
3114 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3115 void Threads::threads_do(ThreadClosure* tc) {
3116 assert_locked_or_safepoint(Threads_lock);
3117 // ALL_JAVA_THREADS iterates through all JavaThreads
3118 ALL_JAVA_THREADS(p) {
3119 tc->do_thread(p);
3120 }
3121 // Someday we could have a table or list of all non-JavaThreads.
3122 // For now, just manually iterate through them.
3123 tc->do_thread(VMThread::vm_thread());
3124 Universe::heap()->gc_threads_do(tc);
3125 WatcherThread *wt = WatcherThread::watcher_thread();
3126 // Strictly speaking, the following NULL check isn't sufficient to make sure
3127 // the data for WatcherThread is still valid upon being examined. However,
3128 // considering that WatchThread terminates when the VM is on the way to
3129 // exit at safepoint, the chance of the above is extremely small. The right
3130 // way to prevent termination of WatcherThread would be to acquire
3131 // Terminator_lock, but we can't do that without violating the lock rank
3132 // checking in some cases.
3133 if (wt != NULL)
3134 tc->do_thread(wt);
3136 // If CompilerThreads ever become non-JavaThreads, add them here
3137 }
3139 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3141 extern void JDK_Version_init();
3143 // Check version
3144 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3146 // Initialize the output stream module
3147 ostream_init();
3149 // Process java launcher properties.
3150 Arguments::process_sun_java_launcher_properties(args);
3152 // Initialize the os module before using TLS
3153 os::init();
3155 // Initialize system properties.
3156 Arguments::init_system_properties();
3158 // So that JDK version can be used as a discrimintor when parsing arguments
3159 JDK_Version_init();
3161 // Update/Initialize System properties after JDK version number is known
3162 Arguments::init_version_specific_system_properties();
3164 // Parse arguments
3165 jint parse_result = Arguments::parse(args);
3166 if (parse_result != JNI_OK) return parse_result;
3168 if (PauseAtStartup) {
3169 os::pause();
3170 }
3172 #ifndef USDT2
3173 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3174 #else /* USDT2 */
3175 HOTSPOT_VM_INIT_BEGIN();
3176 #endif /* USDT2 */
3178 // Record VM creation timing statistics
3179 TraceVmCreationTime create_vm_timer;
3180 create_vm_timer.start();
3182 // Timing (must come after argument parsing)
3183 TraceTime timer("Create VM", TraceStartupTime);
3185 // Initialize the os module after parsing the args
3186 jint os_init_2_result = os::init_2();
3187 if (os_init_2_result != JNI_OK) return os_init_2_result;
3189 // Initialize output stream logging
3190 ostream_init_log();
3192 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3193 // Must be before create_vm_init_agents()
3194 if (Arguments::init_libraries_at_startup()) {
3195 convert_vm_init_libraries_to_agents();
3196 }
3198 // Launch -agentlib/-agentpath and converted -Xrun agents
3199 if (Arguments::init_agents_at_startup()) {
3200 create_vm_init_agents();
3201 }
3203 // Initialize Threads state
3204 _thread_list = NULL;
3205 _number_of_threads = 0;
3206 _number_of_non_daemon_threads = 0;
3208 // Initialize TLS
3209 ThreadLocalStorage::init();
3211 // Initialize global data structures and create system classes in heap
3212 vm_init_globals();
3214 // Attach the main thread to this os thread
3215 JavaThread* main_thread = new JavaThread();
3216 main_thread->set_thread_state(_thread_in_vm);
3217 // must do this before set_active_handles and initialize_thread_local_storage
3218 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3219 // change the stack size recorded here to one based on the java thread
3220 // stacksize. This adjusted size is what is used to figure the placement
3221 // of the guard pages.
3222 main_thread->record_stack_base_and_size();
3223 main_thread->initialize_thread_local_storage();
3225 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3227 if (!main_thread->set_as_starting_thread()) {
3228 vm_shutdown_during_initialization(
3229 "Failed necessary internal allocation. Out of swap space");
3230 delete main_thread;
3231 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3232 return JNI_ENOMEM;
3233 }
3235 // Enable guard page *after* os::create_main_thread(), otherwise it would
3236 // crash Linux VM, see notes in os_linux.cpp.
3237 main_thread->create_stack_guard_pages();
3239 // Initialize Java-Level synchronization subsystem
3240 ObjectMonitor::Initialize() ;
3242 // Initialize global modules
3243 jint status = init_globals();
3244 if (status != JNI_OK) {
3245 delete main_thread;
3246 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3247 return status;
3248 }
3250 // Should be done after the heap is fully created
3251 main_thread->cache_global_variables();
3253 HandleMark hm;
3255 { MutexLocker mu(Threads_lock);
3256 Threads::add(main_thread);
3257 }
3259 // Any JVMTI raw monitors entered in onload will transition into
3260 // real raw monitor. VM is setup enough here for raw monitor enter.
3261 JvmtiExport::transition_pending_onload_raw_monitors();
3263 if (VerifyBeforeGC &&
3264 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3265 Universe::heap()->prepare_for_verify();
3266 Universe::verify(); // make sure we're starting with a clean slate
3267 }
3269 // Create the VMThread
3270 { TraceTime timer("Start VMThread", TraceStartupTime);
3271 VMThread::create();
3272 Thread* vmthread = VMThread::vm_thread();
3274 if (!os::create_thread(vmthread, os::vm_thread))
3275 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3277 // Wait for the VM thread to become ready, and VMThread::run to initialize
3278 // Monitors can have spurious returns, must always check another state flag
3279 {
3280 MutexLocker ml(Notify_lock);
3281 os::start_thread(vmthread);
3282 while (vmthread->active_handles() == NULL) {
3283 Notify_lock->wait();
3284 }
3285 }
3286 }
3288 assert (Universe::is_fully_initialized(), "not initialized");
3289 EXCEPTION_MARK;
3291 // At this point, the Universe is initialized, but we have not executed
3292 // any byte code. Now is a good time (the only time) to dump out the
3293 // internal state of the JVM for sharing.
3295 if (DumpSharedSpaces) {
3296 Universe::heap()->preload_and_dump(CHECK_0);
3297 ShouldNotReachHere();
3298 }
3300 // Always call even when there are not JVMTI environments yet, since environments
3301 // may be attached late and JVMTI must track phases of VM execution
3302 JvmtiExport::enter_start_phase();
3304 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3305 JvmtiExport::post_vm_start();
3307 {
3308 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3310 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3311 create_vm_init_libraries();
3312 }
3314 if (InitializeJavaLangString) {
3315 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3316 } else {
3317 warning("java.lang.String not initialized");
3318 }
3320 if (AggressiveOpts) {
3321 {
3322 // Forcibly initialize java/util/HashMap and mutate the private
3323 // static final "frontCacheEnabled" field before we start creating instances
3324 #ifdef ASSERT
3325 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3326 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3327 #endif
3328 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3329 KlassHandle k = KlassHandle(THREAD, k_o);
3330 guarantee(k.not_null(), "Must find java/util/HashMap");
3331 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3332 ik->initialize(CHECK_0);
3333 fieldDescriptor fd;
3334 // Possible we might not find this field; if so, don't break
3335 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3336 k()->java_mirror()->bool_field_put(fd.offset(), true);
3337 }
3338 }
3340 if (UseStringCache) {
3341 // Forcibly initialize java/lang/StringValue and mutate the private
3342 // static final "stringCacheEnabled" field before we start creating instances
3343 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3344 // Possible that StringValue isn't present: if so, silently don't break
3345 if (k_o != NULL) {
3346 KlassHandle k = KlassHandle(THREAD, k_o);
3347 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3348 ik->initialize(CHECK_0);
3349 fieldDescriptor fd;
3350 // Possible we might not find this field: if so, silently don't break
3351 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3352 k()->java_mirror()->bool_field_put(fd.offset(), true);
3353 }
3354 }
3355 }
3356 }
3358 // Initialize java_lang.System (needed before creating the thread)
3359 if (InitializeJavaLangSystem) {
3360 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3361 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3362 Handle thread_group = create_initial_thread_group(CHECK_0);
3363 Universe::set_main_thread_group(thread_group());
3364 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3365 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3366 main_thread->set_threadObj(thread_object);
3367 // Set thread status to running since main thread has
3368 // been started and running.
3369 java_lang_Thread::set_thread_status(thread_object,
3370 java_lang_Thread::RUNNABLE);
3372 // The VM preresolve methods to these classes. Make sure that get initialized
3373 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3374 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3375 // The VM creates & returns objects of this class. Make sure it's initialized.
3376 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3377 call_initializeSystemClass(CHECK_0);
3379 // get the Java runtime name after java.lang.System is initialized
3380 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3381 } else {
3382 warning("java.lang.System not initialized");
3383 }
3385 // an instance of OutOfMemory exception has been allocated earlier
3386 if (InitializeJavaLangExceptionsErrors) {
3387 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3388 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3389 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3390 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3391 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3392 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3393 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3394 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK_0);
3395 } else {
3396 warning("java.lang.OutOfMemoryError has not been initialized");
3397 warning("java.lang.NullPointerException has not been initialized");
3398 warning("java.lang.ClassCastException has not been initialized");
3399 warning("java.lang.ArrayStoreException has not been initialized");
3400 warning("java.lang.ArithmeticException has not been initialized");
3401 warning("java.lang.StackOverflowError has not been initialized");
3402 warning("java.lang.IllegalArgumentException has not been initialized");
3403 }
3404 }
3406 // See : bugid 4211085.
3407 // Background : the static initializer of java.lang.Compiler tries to read
3408 // property"java.compiler" and read & write property "java.vm.info".
3409 // When a security manager is installed through the command line
3410 // option "-Djava.security.manager", the above properties are not
3411 // readable and the static initializer for java.lang.Compiler fails
3412 // resulting in a NoClassDefFoundError. This can happen in any
3413 // user code which calls methods in java.lang.Compiler.
3414 // Hack : the hack is to pre-load and initialize this class, so that only
3415 // system domains are on the stack when the properties are read.
3416 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3417 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3418 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3419 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3420 // Once that is done, we should remove this hack.
3421 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3423 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3424 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3425 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3426 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3427 // This should also be taken out as soon as 4211383 gets fixed.
3428 reset_vm_info_property(CHECK_0);
3430 quicken_jni_functions();
3432 // Must be run after init_ft which initializes ft_enabled
3433 if (TRACE_INITIALIZE() != JNI_OK) {
3434 vm_exit_during_initialization("Failed to initialize tracing backend");
3435 }
3437 // Set flag that basic initialization has completed. Used by exceptions and various
3438 // debug stuff, that does not work until all basic classes have been initialized.
3439 set_init_completed();
3441 #ifndef USDT2
3442 HS_DTRACE_PROBE(hotspot, vm__init__end);
3443 #else /* USDT2 */
3444 HOTSPOT_VM_INIT_END();
3445 #endif /* USDT2 */
3447 // record VM initialization completion time
3448 Management::record_vm_init_completed();
3450 // Compute system loader. Note that this has to occur after set_init_completed, since
3451 // valid exceptions may be thrown in the process.
3452 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3453 // set_init_completed has just been called, causing exceptions not to be shortcut
3454 // anymore. We call vm_exit_during_initialization directly instead.
3455 SystemDictionary::compute_java_system_loader(THREAD);
3456 if (HAS_PENDING_EXCEPTION) {
3457 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3458 }
3460 #ifndef SERIALGC
3461 // Support for ConcurrentMarkSweep. This should be cleaned up
3462 // and better encapsulated. The ugly nested if test would go away
3463 // once things are properly refactored. XXX YSR
3464 if (UseConcMarkSweepGC || UseG1GC) {
3465 if (UseConcMarkSweepGC) {
3466 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3467 } else {
3468 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3469 }
3470 if (HAS_PENDING_EXCEPTION) {
3471 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3472 }
3473 }
3474 #endif // SERIALGC
3476 // Always call even when there are not JVMTI environments yet, since environments
3477 // may be attached late and JVMTI must track phases of VM execution
3478 JvmtiExport::enter_live_phase();
3480 // Signal Dispatcher needs to be started before VMInit event is posted
3481 os::signal_init();
3483 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3484 if (!DisableAttachMechanism) {
3485 if (StartAttachListener || AttachListener::init_at_startup()) {
3486 AttachListener::init();
3487 }
3488 }
3490 // Launch -Xrun agents
3491 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3492 // back-end can launch with -Xdebug -Xrunjdwp.
3493 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3494 create_vm_init_libraries();
3495 }
3497 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3498 JvmtiExport::post_vm_initialized();
3500 if (!TRACE_START()) {
3501 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3502 }
3504 if (CleanChunkPoolAsync) {
3505 Chunk::start_chunk_pool_cleaner_task();
3506 }
3508 // initialize compiler(s)
3509 CompileBroker::compilation_init();
3511 Management::initialize(THREAD);
3512 if (HAS_PENDING_EXCEPTION) {
3513 // management agent fails to start possibly due to
3514 // configuration problem and is responsible for printing
3515 // stack trace if appropriate. Simply exit VM.
3516 vm_exit(1);
3517 }
3519 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3520 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3521 if (MemProfiling) MemProfiler::engage();
3522 StatSampler::engage();
3523 if (CheckJNICalls) JniPeriodicChecker::engage();
3525 BiasedLocking::init();
3527 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3528 call_postVMInitHook(THREAD);
3529 // The Java side of PostVMInitHook.run must deal with all
3530 // exceptions and provide means of diagnosis.
3531 if (HAS_PENDING_EXCEPTION) {
3532 CLEAR_PENDING_EXCEPTION;
3533 }
3534 }
3536 // Start up the WatcherThread if there are any periodic tasks
3537 // NOTE: All PeriodicTasks should be registered by now. If they
3538 // aren't, late joiners might appear to start slowly (we might
3539 // take a while to process their first tick).
3540 if (PeriodicTask::num_tasks() > 0) {
3541 WatcherThread::start();
3542 }
3544 // Give os specific code one last chance to start
3545 os::init_3();
3547 create_vm_timer.end();
3548 return JNI_OK;
3549 }
3551 // type for the Agent_OnLoad and JVM_OnLoad entry points
3552 extern "C" {
3553 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3554 }
3555 // Find a command line agent library and return its entry point for
3556 // -agentlib: -agentpath: -Xrun
3557 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3558 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3559 OnLoadEntry_t on_load_entry = NULL;
3560 void *library = agent->os_lib(); // check if we have looked it up before
3562 if (library == NULL) {
3563 char buffer[JVM_MAXPATHLEN];
3564 char ebuf[1024];
3565 const char *name = agent->name();
3566 const char *msg = "Could not find agent library ";
3568 if (agent->is_absolute_path()) {
3569 library = os::dll_load(name, ebuf, sizeof ebuf);
3570 if (library == NULL) {
3571 const char *sub_msg = " in absolute path, with error: ";
3572 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3573 char *buf = NEW_C_HEAP_ARRAY(char, len);
3574 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3575 // If we can't find the agent, exit.
3576 vm_exit_during_initialization(buf, NULL);
3577 FREE_C_HEAP_ARRAY(char, buf);
3578 }
3579 } else {
3580 // Try to load the agent from the standard dll directory
3581 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3582 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3583 #ifdef KERNEL
3584 // Download instrument dll
3585 if (library == NULL && strcmp(name, "instrument") == 0) {
3586 char *props = Arguments::get_kernel_properties();
3587 char *home = Arguments::get_java_home();
3588 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3589 " sun.jkernel.DownloadManager -download client_jvm";
3590 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3591 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3592 jio_snprintf(cmd, length, fmt, home, props);
3593 int status = os::fork_and_exec(cmd);
3594 FreeHeap(props);
3595 if (status == -1) {
3596 warning(cmd);
3597 vm_exit_during_initialization("fork_and_exec failed: %s",
3598 strerror(errno));
3599 }
3600 FREE_C_HEAP_ARRAY(char, cmd);
3601 // when this comes back the instrument.dll should be where it belongs.
3602 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3603 }
3604 #endif // KERNEL
3605 if (library == NULL) { // Try the local directory
3606 char ns[1] = {0};
3607 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3608 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3609 if (library == NULL) {
3610 const char *sub_msg = " on the library path, with error: ";
3611 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3612 char *buf = NEW_C_HEAP_ARRAY(char, len);
3613 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3614 // If we can't find the agent, exit.
3615 vm_exit_during_initialization(buf, NULL);
3616 FREE_C_HEAP_ARRAY(char, buf);
3617 }
3618 }
3619 }
3620 agent->set_os_lib(library);
3621 }
3623 // Find the OnLoad function.
3624 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3625 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3626 if (on_load_entry != NULL) break;
3627 }
3628 return on_load_entry;
3629 }
3631 // Find the JVM_OnLoad entry point
3632 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3633 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3634 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3635 }
3637 // Find the Agent_OnLoad entry point
3638 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3639 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3640 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3641 }
3643 // For backwards compatibility with -Xrun
3644 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3645 // treated like -agentpath:
3646 // Must be called before agent libraries are created
3647 void Threads::convert_vm_init_libraries_to_agents() {
3648 AgentLibrary* agent;
3649 AgentLibrary* next;
3651 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3652 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3653 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3655 // If there is an JVM_OnLoad function it will get called later,
3656 // otherwise see if there is an Agent_OnLoad
3657 if (on_load_entry == NULL) {
3658 on_load_entry = lookup_agent_on_load(agent);
3659 if (on_load_entry != NULL) {
3660 // switch it to the agent list -- so that Agent_OnLoad will be called,
3661 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3662 Arguments::convert_library_to_agent(agent);
3663 } else {
3664 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3665 }
3666 }
3667 }
3668 }
3670 // Create agents for -agentlib: -agentpath: and converted -Xrun
3671 // Invokes Agent_OnLoad
3672 // Called very early -- before JavaThreads exist
3673 void Threads::create_vm_init_agents() {
3674 extern struct JavaVM_ main_vm;
3675 AgentLibrary* agent;
3677 JvmtiExport::enter_onload_phase();
3678 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3679 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3681 if (on_load_entry != NULL) {
3682 // Invoke the Agent_OnLoad function
3683 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3684 if (err != JNI_OK) {
3685 vm_exit_during_initialization("agent library failed to init", agent->name());
3686 }
3687 } else {
3688 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3689 }
3690 }
3691 JvmtiExport::enter_primordial_phase();
3692 }
3694 extern "C" {
3695 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3696 }
3698 void Threads::shutdown_vm_agents() {
3699 // Send any Agent_OnUnload notifications
3700 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3701 extern struct JavaVM_ main_vm;
3702 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3704 // Find the Agent_OnUnload function.
3705 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3706 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3707 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3709 // Invoke the Agent_OnUnload function
3710 if (unload_entry != NULL) {
3711 JavaThread* thread = JavaThread::current();
3712 ThreadToNativeFromVM ttn(thread);
3713 HandleMark hm(thread);
3714 (*unload_entry)(&main_vm);
3715 break;
3716 }
3717 }
3718 }
3719 }
3721 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3722 // Invokes JVM_OnLoad
3723 void Threads::create_vm_init_libraries() {
3724 extern struct JavaVM_ main_vm;
3725 AgentLibrary* agent;
3727 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3728 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3730 if (on_load_entry != NULL) {
3731 // Invoke the JVM_OnLoad function
3732 JavaThread* thread = JavaThread::current();
3733 ThreadToNativeFromVM ttn(thread);
3734 HandleMark hm(thread);
3735 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3736 if (err != JNI_OK) {
3737 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3738 }
3739 } else {
3740 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3741 }
3742 }
3743 }
3745 // Last thread running calls java.lang.Shutdown.shutdown()
3746 void JavaThread::invoke_shutdown_hooks() {
3747 HandleMark hm(this);
3749 // We could get here with a pending exception, if so clear it now.
3750 if (this->has_pending_exception()) {
3751 this->clear_pending_exception();
3752 }
3754 EXCEPTION_MARK;
3755 klassOop k =
3756 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3757 THREAD);
3758 if (k != NULL) {
3759 // SystemDictionary::resolve_or_null will return null if there was
3760 // an exception. If we cannot load the Shutdown class, just don't
3761 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3762 // and finalizers (if runFinalizersOnExit is set) won't be run.
3763 // Note that if a shutdown hook was registered or runFinalizersOnExit
3764 // was called, the Shutdown class would have already been loaded
3765 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3766 instanceKlassHandle shutdown_klass (THREAD, k);
3767 JavaValue result(T_VOID);
3768 JavaCalls::call_static(&result,
3769 shutdown_klass,
3770 vmSymbols::shutdown_method_name(),
3771 vmSymbols::void_method_signature(),
3772 THREAD);
3773 }
3774 CLEAR_PENDING_EXCEPTION;
3775 }
3777 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3778 // the program falls off the end of main(). Another VM exit path is through
3779 // vm_exit() when the program calls System.exit() to return a value or when
3780 // there is a serious error in VM. The two shutdown paths are not exactly
3781 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3782 // and VM_Exit op at VM level.
3783 //
3784 // Shutdown sequence:
3785 // + Wait until we are the last non-daemon thread to execute
3786 // <-- every thing is still working at this moment -->
3787 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3788 // shutdown hooks, run finalizers if finalization-on-exit
3789 // + Call before_exit(), prepare for VM exit
3790 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3791 // currently the only user of this mechanism is File.deleteOnExit())
3792 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3793 // post thread end and vm death events to JVMTI,
3794 // stop signal thread
3795 // + Call JavaThread::exit(), it will:
3796 // > release JNI handle blocks, remove stack guard pages
3797 // > remove this thread from Threads list
3798 // <-- no more Java code from this thread after this point -->
3799 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3800 // the compiler threads at safepoint
3801 // <-- do not use anything that could get blocked by Safepoint -->
3802 // + Disable tracing at JNI/JVM barriers
3803 // + Set _vm_exited flag for threads that are still running native code
3804 // + Delete this thread
3805 // + Call exit_globals()
3806 // > deletes tty
3807 // > deletes PerfMemory resources
3808 // + Return to caller
3810 bool Threads::destroy_vm() {
3811 JavaThread* thread = JavaThread::current();
3813 // Wait until we are the last non-daemon thread to execute
3814 { MutexLocker nu(Threads_lock);
3815 while (Threads::number_of_non_daemon_threads() > 1 )
3816 // This wait should make safepoint checks, wait without a timeout,
3817 // and wait as a suspend-equivalent condition.
3818 //
3819 // Note: If the FlatProfiler is running and this thread is waiting
3820 // for another non-daemon thread to finish, then the FlatProfiler
3821 // is waiting for the external suspend request on this thread to
3822 // complete. wait_for_ext_suspend_completion() will eventually
3823 // timeout, but that takes time. Making this wait a suspend-
3824 // equivalent condition solves that timeout problem.
3825 //
3826 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3827 Mutex::_as_suspend_equivalent_flag);
3828 }
3830 // Hang forever on exit if we are reporting an error.
3831 if (ShowMessageBoxOnError && is_error_reported()) {
3832 os::infinite_sleep();
3833 }
3834 os::wait_for_keypress_at_exit();
3836 if (JDK_Version::is_jdk12x_version()) {
3837 // We are the last thread running, so check if finalizers should be run.
3838 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3839 HandleMark rm(thread);
3840 Universe::run_finalizers_on_exit();
3841 } else {
3842 // run Java level shutdown hooks
3843 thread->invoke_shutdown_hooks();
3844 }
3846 before_exit(thread);
3848 thread->exit(true);
3850 // Stop VM thread.
3851 {
3852 // 4945125 The vm thread comes to a safepoint during exit.
3853 // GC vm_operations can get caught at the safepoint, and the
3854 // heap is unparseable if they are caught. Grab the Heap_lock
3855 // to prevent this. The GC vm_operations will not be able to
3856 // queue until after the vm thread is dead.
3857 // After this point, we'll never emerge out of the safepoint before
3858 // the VM exits, so concurrent GC threads do not need to be explicitly
3859 // stopped; they remain inactive until the process exits.
3860 // Note: some concurrent G1 threads may be running during a safepoint,
3861 // but these will not be accessing the heap, just some G1-specific side
3862 // data structures that are not accessed by any other threads but them
3863 // after this point in a terminal safepoint.
3865 MutexLocker ml(Heap_lock);
3867 VMThread::wait_for_vm_thread_exit();
3868 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3869 VMThread::destroy();
3870 }
3872 // clean up ideal graph printers
3873 #if defined(COMPILER2) && !defined(PRODUCT)
3874 IdealGraphPrinter::clean_up();
3875 #endif
3877 // Now, all Java threads are gone except daemon threads. Daemon threads
3878 // running Java code or in VM are stopped by the Safepoint. However,
3879 // daemon threads executing native code are still running. But they
3880 // will be stopped at native=>Java/VM barriers. Note that we can't
3881 // simply kill or suspend them, as it is inherently deadlock-prone.
3883 #ifndef PRODUCT
3884 // disable function tracing at JNI/JVM barriers
3885 TraceJNICalls = false;
3886 TraceJVMCalls = false;
3887 TraceRuntimeCalls = false;
3888 #endif
3890 VM_Exit::set_vm_exited();
3892 notify_vm_shutdown();
3894 delete thread;
3896 // exit_globals() will delete tty
3897 exit_globals();
3899 return true;
3900 }
3903 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3904 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3905 return is_supported_jni_version(version);
3906 }
3909 jboolean Threads::is_supported_jni_version(jint version) {
3910 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3911 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3912 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3913 return JNI_FALSE;
3914 }
3917 void Threads::add(JavaThread* p, bool force_daemon) {
3918 // The threads lock must be owned at this point
3919 assert_locked_or_safepoint(Threads_lock);
3921 // See the comment for this method in thread.hpp for its purpose and
3922 // why it is called here.
3923 p->initialize_queues();
3924 p->set_next(_thread_list);
3925 _thread_list = p;
3926 _number_of_threads++;
3927 oop threadObj = p->threadObj();
3928 bool daemon = true;
3929 // Bootstrapping problem: threadObj can be null for initial
3930 // JavaThread (or for threads attached via JNI)
3931 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3932 _number_of_non_daemon_threads++;
3933 daemon = false;
3934 }
3936 ThreadService::add_thread(p, daemon);
3938 // Possible GC point.
3939 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3940 }
3942 void Threads::remove(JavaThread* p) {
3943 // Extra scope needed for Thread_lock, so we can check
3944 // that we do not remove thread without safepoint code notice
3945 { MutexLocker ml(Threads_lock);
3947 assert(includes(p), "p must be present");
3949 JavaThread* current = _thread_list;
3950 JavaThread* prev = NULL;
3952 while (current != p) {
3953 prev = current;
3954 current = current->next();
3955 }
3957 if (prev) {
3958 prev->set_next(current->next());
3959 } else {
3960 _thread_list = p->next();
3961 }
3962 _number_of_threads--;
3963 oop threadObj = p->threadObj();
3964 bool daemon = true;
3965 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3966 _number_of_non_daemon_threads--;
3967 daemon = false;
3969 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3970 // on destroy_vm will wake up.
3971 if (number_of_non_daemon_threads() == 1)
3972 Threads_lock->notify_all();
3973 }
3974 ThreadService::remove_thread(p, daemon);
3976 // Make sure that safepoint code disregard this thread. This is needed since
3977 // the thread might mess around with locks after this point. This can cause it
3978 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3979 // of this thread since it is removed from the queue.
3980 p->set_terminated_value();
3981 } // unlock Threads_lock
3983 // Since Events::log uses a lock, we grab it outside the Threads_lock
3984 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
3985 }
3987 // Threads_lock must be held when this is called (or must be called during a safepoint)
3988 bool Threads::includes(JavaThread* p) {
3989 assert(Threads_lock->is_locked(), "sanity check");
3990 ALL_JAVA_THREADS(q) {
3991 if (q == p ) {
3992 return true;
3993 }
3994 }
3995 return false;
3996 }
3998 // Operations on the Threads list for GC. These are not explicitly locked,
3999 // but the garbage collector must provide a safe context for them to run.
4000 // In particular, these things should never be called when the Threads_lock
4001 // is held by some other thread. (Note: the Safepoint abstraction also
4002 // uses the Threads_lock to gurantee this property. It also makes sure that
4003 // all threads gets blocked when exiting or starting).
4005 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4006 ALL_JAVA_THREADS(p) {
4007 p->oops_do(f, cf);
4008 }
4009 VMThread::vm_thread()->oops_do(f, cf);
4010 }
4012 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
4013 // Introduce a mechanism allowing parallel threads to claim threads as
4014 // root groups. Overhead should be small enough to use all the time,
4015 // even in sequential code.
4016 SharedHeap* sh = SharedHeap::heap();
4017 // Cannot yet substitute active_workers for n_par_threads
4018 // because of G1CollectedHeap::verify() use of
4019 // SharedHeap::process_strong_roots(). n_par_threads == 0 will
4020 // turn off parallelism in process_strong_roots while active_workers
4021 // is being used for parallelism elsewhere.
4022 bool is_par = sh->n_par_threads() > 0;
4023 assert(!is_par ||
4024 (SharedHeap::heap()->n_par_threads() ==
4025 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4026 int cp = SharedHeap::heap()->strong_roots_parity();
4027 ALL_JAVA_THREADS(p) {
4028 if (p->claim_oops_do(is_par, cp)) {
4029 p->oops_do(f, cf);
4030 }
4031 }
4032 VMThread* vmt = VMThread::vm_thread();
4033 if (vmt->claim_oops_do(is_par, cp)) {
4034 vmt->oops_do(f, cf);
4035 }
4036 }
4038 #ifndef SERIALGC
4039 // Used by ParallelScavenge
4040 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4041 ALL_JAVA_THREADS(p) {
4042 q->enqueue(new ThreadRootsTask(p));
4043 }
4044 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4045 }
4047 // Used by Parallel Old
4048 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4049 ALL_JAVA_THREADS(p) {
4050 q->enqueue(new ThreadRootsMarkingTask(p));
4051 }
4052 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4053 }
4054 #endif // SERIALGC
4056 void Threads::nmethods_do(CodeBlobClosure* cf) {
4057 ALL_JAVA_THREADS(p) {
4058 p->nmethods_do(cf);
4059 }
4060 VMThread::vm_thread()->nmethods_do(cf);
4061 }
4063 void Threads::gc_epilogue() {
4064 ALL_JAVA_THREADS(p) {
4065 p->gc_epilogue();
4066 }
4067 }
4069 void Threads::gc_prologue() {
4070 ALL_JAVA_THREADS(p) {
4071 p->gc_prologue();
4072 }
4073 }
4075 void Threads::deoptimized_wrt_marked_nmethods() {
4076 ALL_JAVA_THREADS(p) {
4077 p->deoptimized_wrt_marked_nmethods();
4078 }
4079 }
4082 // Get count Java threads that are waiting to enter the specified monitor.
4083 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4084 address monitor, bool doLock) {
4085 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4086 "must grab Threads_lock or be at safepoint");
4087 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4089 int i = 0;
4090 {
4091 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4092 ALL_JAVA_THREADS(p) {
4093 if (p->is_Compiler_thread()) continue;
4095 address pending = (address)p->current_pending_monitor();
4096 if (pending == monitor) { // found a match
4097 if (i < count) result->append(p); // save the first count matches
4098 i++;
4099 }
4100 }
4101 }
4102 return result;
4103 }
4106 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4107 assert(doLock ||
4108 Threads_lock->owned_by_self() ||
4109 SafepointSynchronize::is_at_safepoint(),
4110 "must grab Threads_lock or be at safepoint");
4112 // NULL owner means not locked so we can skip the search
4113 if (owner == NULL) return NULL;
4115 {
4116 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4117 ALL_JAVA_THREADS(p) {
4118 // first, see if owner is the address of a Java thread
4119 if (owner == (address)p) return p;
4120 }
4121 }
4122 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
4123 if (UseHeavyMonitors) return NULL;
4125 //
4126 // If we didn't find a matching Java thread and we didn't force use of
4127 // heavyweight monitors, then the owner is the stack address of the
4128 // Lock Word in the owning Java thread's stack.
4129 //
4130 JavaThread* the_owner = NULL;
4131 {
4132 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4133 ALL_JAVA_THREADS(q) {
4134 if (q->is_lock_owned(owner)) {
4135 the_owner = q;
4136 break;
4137 }
4138 }
4139 }
4140 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
4141 return the_owner;
4142 }
4144 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4145 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4146 char buf[32];
4147 st->print_cr(os::local_time_string(buf, sizeof(buf)));
4149 st->print_cr("Full thread dump %s (%s %s):",
4150 Abstract_VM_Version::vm_name(),
4151 Abstract_VM_Version::vm_release(),
4152 Abstract_VM_Version::vm_info_string()
4153 );
4154 st->cr();
4156 #ifndef SERIALGC
4157 // Dump concurrent locks
4158 ConcurrentLocksDump concurrent_locks;
4159 if (print_concurrent_locks) {
4160 concurrent_locks.dump_at_safepoint();
4161 }
4162 #endif // SERIALGC
4164 ALL_JAVA_THREADS(p) {
4165 ResourceMark rm;
4166 p->print_on(st);
4167 if (print_stacks) {
4168 if (internal_format) {
4169 p->trace_stack();
4170 } else {
4171 p->print_stack_on(st);
4172 }
4173 }
4174 st->cr();
4175 #ifndef SERIALGC
4176 if (print_concurrent_locks) {
4177 concurrent_locks.print_locks_on(p, st);
4178 }
4179 #endif // SERIALGC
4180 }
4182 VMThread::vm_thread()->print_on(st);
4183 st->cr();
4184 Universe::heap()->print_gc_threads_on(st);
4185 WatcherThread* wt = WatcherThread::watcher_thread();
4186 if (wt != NULL) wt->print_on(st);
4187 st->cr();
4188 CompileBroker::print_compiler_threads_on(st);
4189 st->flush();
4190 }
4192 // Threads::print_on_error() is called by fatal error handler. It's possible
4193 // that VM is not at safepoint and/or current thread is inside signal handler.
4194 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4195 // memory (even in resource area), it might deadlock the error handler.
4196 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4197 bool found_current = false;
4198 st->print_cr("Java Threads: ( => current thread )");
4199 ALL_JAVA_THREADS(thread) {
4200 bool is_current = (current == thread);
4201 found_current = found_current || is_current;
4203 st->print("%s", is_current ? "=>" : " ");
4205 st->print(PTR_FORMAT, thread);
4206 st->print(" ");
4207 thread->print_on_error(st, buf, buflen);
4208 st->cr();
4209 }
4210 st->cr();
4212 st->print_cr("Other Threads:");
4213 if (VMThread::vm_thread()) {
4214 bool is_current = (current == VMThread::vm_thread());
4215 found_current = found_current || is_current;
4216 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4218 st->print(PTR_FORMAT, VMThread::vm_thread());
4219 st->print(" ");
4220 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4221 st->cr();
4222 }
4223 WatcherThread* wt = WatcherThread::watcher_thread();
4224 if (wt != NULL) {
4225 bool is_current = (current == wt);
4226 found_current = found_current || is_current;
4227 st->print("%s", is_current ? "=>" : " ");
4229 st->print(PTR_FORMAT, wt);
4230 st->print(" ");
4231 wt->print_on_error(st, buf, buflen);
4232 st->cr();
4233 }
4234 if (!found_current) {
4235 st->cr();
4236 st->print("=>" PTR_FORMAT " (exited) ", current);
4237 current->print_on_error(st, buf, buflen);
4238 st->cr();
4239 }
4240 }
4242 // Internal SpinLock and Mutex
4243 // Based on ParkEvent
4245 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4246 //
4247 // We employ SpinLocks _only for low-contention, fixed-length
4248 // short-duration critical sections where we're concerned
4249 // about native mutex_t or HotSpot Mutex:: latency.
4250 // The mux construct provides a spin-then-block mutual exclusion
4251 // mechanism.
4252 //
4253 // Testing has shown that contention on the ListLock guarding gFreeList
4254 // is common. If we implement ListLock as a simple SpinLock it's common
4255 // for the JVM to devolve to yielding with little progress. This is true
4256 // despite the fact that the critical sections protected by ListLock are
4257 // extremely short.
4258 //
4259 // TODO-FIXME: ListLock should be of type SpinLock.
4260 // We should make this a 1st-class type, integrated into the lock
4261 // hierarchy as leaf-locks. Critically, the SpinLock structure
4262 // should have sufficient padding to avoid false-sharing and excessive
4263 // cache-coherency traffic.
4266 typedef volatile int SpinLockT ;
4268 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4269 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4270 return ; // normal fast-path return
4271 }
4273 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4274 TEVENT (SpinAcquire - ctx) ;
4275 int ctr = 0 ;
4276 int Yields = 0 ;
4277 for (;;) {
4278 while (*adr != 0) {
4279 ++ctr ;
4280 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4281 if (Yields > 5) {
4282 // Consider using a simple NakedSleep() instead.
4283 // Then SpinAcquire could be called by non-JVM threads
4284 Thread::current()->_ParkEvent->park(1) ;
4285 } else {
4286 os::NakedYield() ;
4287 ++Yields ;
4288 }
4289 } else {
4290 SpinPause() ;
4291 }
4292 }
4293 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4294 }
4295 }
4297 void Thread::SpinRelease (volatile int * adr) {
4298 assert (*adr != 0, "invariant") ;
4299 OrderAccess::fence() ; // guarantee at least release consistency.
4300 // Roach-motel semantics.
4301 // It's safe if subsequent LDs and STs float "up" into the critical section,
4302 // but prior LDs and STs within the critical section can't be allowed
4303 // to reorder or float past the ST that releases the lock.
4304 *adr = 0 ;
4305 }
4307 // muxAcquire and muxRelease:
4308 //
4309 // * muxAcquire and muxRelease support a single-word lock-word construct.
4310 // The LSB of the word is set IFF the lock is held.
4311 // The remainder of the word points to the head of a singly-linked list
4312 // of threads blocked on the lock.
4313 //
4314 // * The current implementation of muxAcquire-muxRelease uses its own
4315 // dedicated Thread._MuxEvent instance. If we're interested in
4316 // minimizing the peak number of extant ParkEvent instances then
4317 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4318 // as certain invariants were satisfied. Specifically, care would need
4319 // to be taken with regards to consuming unpark() "permits".
4320 // A safe rule of thumb is that a thread would never call muxAcquire()
4321 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4322 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4323 // consume an unpark() permit intended for monitorenter, for instance.
4324 // One way around this would be to widen the restricted-range semaphore
4325 // implemented in park(). Another alternative would be to provide
4326 // multiple instances of the PlatformEvent() for each thread. One
4327 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4328 //
4329 // * Usage:
4330 // -- Only as leaf locks
4331 // -- for short-term locking only as muxAcquire does not perform
4332 // thread state transitions.
4333 //
4334 // Alternatives:
4335 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4336 // but with parking or spin-then-park instead of pure spinning.
4337 // * Use Taura-Oyama-Yonenzawa locks.
4338 // * It's possible to construct a 1-0 lock if we encode the lockword as
4339 // (List,LockByte). Acquire will CAS the full lockword while Release
4340 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4341 // acquiring threads use timers (ParkTimed) to detect and recover from
4342 // the stranding window. Thread/Node structures must be aligned on 256-byte
4343 // boundaries by using placement-new.
4344 // * Augment MCS with advisory back-link fields maintained with CAS().
4345 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4346 // The validity of the backlinks must be ratified before we trust the value.
4347 // If the backlinks are invalid the exiting thread must back-track through the
4348 // the forward links, which are always trustworthy.
4349 // * Add a successor indication. The LockWord is currently encoded as
4350 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4351 // to provide the usual futile-wakeup optimization.
4352 // See RTStt for details.
4353 // * Consider schedctl.sc_nopreempt to cover the critical section.
4354 //
4357 typedef volatile intptr_t MutexT ; // Mux Lock-word
4358 enum MuxBits { LOCKBIT = 1 } ;
4360 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4361 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4362 if (w == 0) return ;
4363 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4364 return ;
4365 }
4367 TEVENT (muxAcquire - Contention) ;
4368 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4369 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4370 for (;;) {
4371 int its = (os::is_MP() ? 100 : 0) + 1 ;
4373 // Optional spin phase: spin-then-park strategy
4374 while (--its >= 0) {
4375 w = *Lock ;
4376 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4377 return ;
4378 }
4379 }
4381 Self->reset() ;
4382 Self->OnList = intptr_t(Lock) ;
4383 // The following fence() isn't _strictly necessary as the subsequent
4384 // CAS() both serializes execution and ratifies the fetched *Lock value.
4385 OrderAccess::fence();
4386 for (;;) {
4387 w = *Lock ;
4388 if ((w & LOCKBIT) == 0) {
4389 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4390 Self->OnList = 0 ; // hygiene - allows stronger asserts
4391 return ;
4392 }
4393 continue ; // Interference -- *Lock changed -- Just retry
4394 }
4395 assert (w & LOCKBIT, "invariant") ;
4396 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4397 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4398 }
4400 while (Self->OnList != 0) {
4401 Self->park() ;
4402 }
4403 }
4404 }
4406 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4407 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4408 if (w == 0) return ;
4409 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4410 return ;
4411 }
4413 TEVENT (muxAcquire - Contention) ;
4414 ParkEvent * ReleaseAfter = NULL ;
4415 if (ev == NULL) {
4416 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4417 }
4418 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4419 for (;;) {
4420 guarantee (ev->OnList == 0, "invariant") ;
4421 int its = (os::is_MP() ? 100 : 0) + 1 ;
4423 // Optional spin phase: spin-then-park strategy
4424 while (--its >= 0) {
4425 w = *Lock ;
4426 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4427 if (ReleaseAfter != NULL) {
4428 ParkEvent::Release (ReleaseAfter) ;
4429 }
4430 return ;
4431 }
4432 }
4434 ev->reset() ;
4435 ev->OnList = intptr_t(Lock) ;
4436 // The following fence() isn't _strictly necessary as the subsequent
4437 // CAS() both serializes execution and ratifies the fetched *Lock value.
4438 OrderAccess::fence();
4439 for (;;) {
4440 w = *Lock ;
4441 if ((w & LOCKBIT) == 0) {
4442 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4443 ev->OnList = 0 ;
4444 // We call ::Release while holding the outer lock, thus
4445 // artificially lengthening the critical section.
4446 // Consider deferring the ::Release() until the subsequent unlock(),
4447 // after we've dropped the outer lock.
4448 if (ReleaseAfter != NULL) {
4449 ParkEvent::Release (ReleaseAfter) ;
4450 }
4451 return ;
4452 }
4453 continue ; // Interference -- *Lock changed -- Just retry
4454 }
4455 assert (w & LOCKBIT, "invariant") ;
4456 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4457 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4458 }
4460 while (ev->OnList != 0) {
4461 ev->park() ;
4462 }
4463 }
4464 }
4466 // Release() must extract a successor from the list and then wake that thread.
4467 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4468 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4469 // Release() would :
4470 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4471 // (B) Extract a successor from the private list "in-hand"
4472 // (C) attempt to CAS() the residual back into *Lock over null.
4473 // If there were any newly arrived threads and the CAS() would fail.
4474 // In that case Release() would detach the RATs, re-merge the list in-hand
4475 // with the RATs and repeat as needed. Alternately, Release() might
4476 // detach and extract a successor, but then pass the residual list to the wakee.
4477 // The wakee would be responsible for reattaching and remerging before it
4478 // competed for the lock.
4479 //
4480 // Both "pop" and DMR are immune from ABA corruption -- there can be
4481 // multiple concurrent pushers, but only one popper or detacher.
4482 // This implementation pops from the head of the list. This is unfair,
4483 // but tends to provide excellent throughput as hot threads remain hot.
4484 // (We wake recently run threads first).
4486 void Thread::muxRelease (volatile intptr_t * Lock) {
4487 for (;;) {
4488 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4489 assert (w & LOCKBIT, "invariant") ;
4490 if (w == LOCKBIT) return ;
4491 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4492 assert (List != NULL, "invariant") ;
4493 assert (List->OnList == intptr_t(Lock), "invariant") ;
4494 ParkEvent * nxt = List->ListNext ;
4496 // The following CAS() releases the lock and pops the head element.
4497 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4498 continue ;
4499 }
4500 List->OnList = 0 ;
4501 OrderAccess::fence() ;
4502 List->unpark () ;
4503 return ;
4504 }
4505 }
4508 void Threads::verify() {
4509 ALL_JAVA_THREADS(p) {
4510 p->verify();
4511 }
4512 VMThread* thread = VMThread::vm_thread();
4513 if (thread != NULL) thread->verify();
4514 }