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 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/scopeDesc.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "interpreter/linkResolver.hpp"
34 #include "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
110
111 #ifdef DTRACE_ENABLED
112
113 // Only bother with this argument setup if dtrace is available
114
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);
122
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 }
135
136 #else /* USDT2 */
137
138 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START
139 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP
140
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 }
153
154 #endif /* USDT2 */
155
156 #else // ndef DTRACE_ENABLED
157
158 #define DTRACE_THREAD_PROBE(probe, javathread)
159
160 #endif // ndef DTRACE_ENABLED
161
162 // Class hierarchy
163 // - Thread
164 // - VMThread
165 // - WatcherThread
166 // - ConcurrentMarkSweepThread
167 // - JavaThread
168 // - CompilerThread
169
170 // ======= Thread ========
171
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 }
193
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 }
202
203
204 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
205 // JavaThread
206
207
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);
214
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);
222
223 // This initial value ==> never claimed.
224 _oops_do_parity = 0;
225
226 // the handle mark links itself to last_handle_mark
227 new HandleMark(this);
228
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 ;
249
250 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
251 _suspend_flags = 0;
252
253 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
254 _hashStateX = os::random() ;
255 _hashStateY = 842502087 ;
256 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
257 _hashStateW = 273326509 ;
258
259 _OnTrap = 0 ;
260 _schedctl = NULL ;
261 _Stalled = 0 ;
262 _TypeTag = 0x2BAD ;
263
264 // Many of the following fields are effectively final - immutable
265 // Note that nascent threads can't use the Native Monitor-Mutex
266 // construct until the _MutexEvent is initialized ...
267 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
268 // we might instead use a stack of ParkEvents that we could provision on-demand.
269 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
270 // and ::Release()
271 _ParkEvent = ParkEvent::Allocate (this) ;
272 _SleepEvent = ParkEvent::Allocate (this) ;
273 _MutexEvent = ParkEvent::Allocate (this) ;
274 _MuxEvent = ParkEvent::Allocate (this) ;
275
276 #ifdef CHECK_UNHANDLED_OOPS
277 if (CheckUnhandledOops) {
278 _unhandled_oops = new UnhandledOops(this);
279 }
280 #endif // CHECK_UNHANDLED_OOPS
281 #ifdef ASSERT
282 if (UseBiasedLocking) {
283 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
284 assert(this == _real_malloc_address ||
285 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
286 "bug in forced alignment of thread objects");
287 }
288 #endif /* ASSERT */
289 }
290
291 void Thread::initialize_thread_local_storage() {
292 // Note: Make sure this method only calls
293 // non-blocking operations. Otherwise, it might not work
294 // with the thread-startup/safepoint interaction.
295
296 // During Java thread startup, safepoint code should allow this
297 // method to complete because it may need to allocate memory to
298 // store information for the new thread.
299
300 // initialize structure dependent on thread local storage
301 ThreadLocalStorage::set_thread(this);
302
303 // set up any platform-specific state.
304 os::initialize_thread();
305
306 }
307
308 void Thread::record_stack_base_and_size() {
309 set_stack_base(os::current_stack_base());
310 set_stack_size(os::current_stack_size());
311 }
312
313
314 Thread::~Thread() {
315 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
316 ObjectSynchronizer::omFlush (this) ;
317
318 // deallocate data structures
319 delete resource_area();
320 // since the handle marks are using the handle area, we have to deallocated the root
321 // handle mark before deallocating the thread's handle area,
322 assert(last_handle_mark() != NULL, "check we have an element");
323 delete last_handle_mark();
324 assert(last_handle_mark() == NULL, "check we have reached the end");
325
326 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
327 // We NULL out the fields for good hygiene.
328 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
329 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
330 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
331 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
332
333 delete handle_area();
334
335 // osthread() can be NULL, if creation of thread failed.
336 if (osthread() != NULL) os::free_thread(osthread());
337
338 delete _SR_lock;
339
340 // clear thread local storage if the Thread is deleting itself
341 if (this == Thread::current()) {
342 ThreadLocalStorage::set_thread(NULL);
343 } else {
344 // In the case where we're not the current thread, invalidate all the
345 // caches in case some code tries to get the current thread or the
346 // thread that was destroyed, and gets stale information.
347 ThreadLocalStorage::invalidate_all();
348 }
349 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
350 }
351
352 // NOTE: dummy function for assertion purpose.
353 void Thread::run() {
354 ShouldNotReachHere();
355 }
356
357 #ifdef ASSERT
358 // Private method to check for dangling thread pointer
359 void check_for_dangling_thread_pointer(Thread *thread) {
360 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
361 "possibility of dangling Thread pointer");
362 }
363 #endif
364
365
366 #ifndef PRODUCT
367 // Tracing method for basic thread operations
368 void Thread::trace(const char* msg, const Thread* const thread) {
369 if (!TraceThreadEvents) return;
370 ResourceMark rm;
371 ThreadCritical tc;
372 const char *name = "non-Java thread";
373 int prio = -1;
374 if (thread->is_Java_thread()
375 && !thread->is_Compiler_thread()) {
376 // The Threads_lock must be held to get information about
377 // this thread but may not be in some situations when
378 // tracing thread events.
379 bool release_Threads_lock = false;
380 if (!Threads_lock->owned_by_self()) {
381 Threads_lock->lock();
382 release_Threads_lock = true;
383 }
384 JavaThread* jt = (JavaThread *)thread;
385 name = (char *)jt->get_thread_name();
386 oop thread_oop = jt->threadObj();
387 if (thread_oop != NULL) {
388 prio = java_lang_Thread::priority(thread_oop);
389 }
390 if (release_Threads_lock) {
391 Threads_lock->unlock();
392 }
393 }
394 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
395 }
396 #endif
397
398
399 ThreadPriority Thread::get_priority(const Thread* const thread) {
400 trace("get priority", thread);
401 ThreadPriority priority;
402 // Can return an error!
403 (void)os::get_priority(thread, priority);
404 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
405 return priority;
406 }
407
408 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
409 trace("set priority", thread);
410 debug_only(check_for_dangling_thread_pointer(thread);)
411 // Can return an error!
412 (void)os::set_priority(thread, priority);
413 }
414
415
416 void Thread::start(Thread* thread) {
417 trace("start", thread);
418 // Start is different from resume in that its safety is guaranteed by context or
419 // being called from a Java method synchronized on the Thread object.
420 if (!DisableStartThread) {
421 if (thread->is_Java_thread()) {
422 // Initialize the thread state to RUNNABLE before starting this thread.
423 // Can not set it after the thread started because we do not know the
424 // exact thread state at that time. It could be in MONITOR_WAIT or
425 // in SLEEPING or some other state.
426 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
427 java_lang_Thread::RUNNABLE);
428 }
429 os::start_thread(thread);
430 }
431 }
432
433 // Enqueue a VM_Operation to do the job for us - sometime later
434 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
435 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
436 VMThread::execute(vm_stop);
437 }
438
439
440 //
441 // Check if an external suspend request has completed (or has been
442 // cancelled). Returns true if the thread is externally suspended and
443 // false otherwise.
444 //
445 // The bits parameter returns information about the code path through
446 // the routine. Useful for debugging:
447 //
448 // set in is_ext_suspend_completed():
449 // 0x00000001 - routine was entered
450 // 0x00000010 - routine return false at end
451 // 0x00000100 - thread exited (return false)
452 // 0x00000200 - suspend request cancelled (return false)
453 // 0x00000400 - thread suspended (return true)
454 // 0x00001000 - thread is in a suspend equivalent state (return true)
455 // 0x00002000 - thread is native and walkable (return true)
456 // 0x00004000 - thread is native_trans and walkable (needed retry)
457 //
458 // set in wait_for_ext_suspend_completion():
459 // 0x00010000 - routine was entered
460 // 0x00020000 - suspend request cancelled before loop (return false)
461 // 0x00040000 - thread suspended before loop (return true)
462 // 0x00080000 - suspend request cancelled in loop (return false)
463 // 0x00100000 - thread suspended in loop (return true)
464 // 0x00200000 - suspend not completed during retry loop (return false)
465 //
466
467 // Helper class for tracing suspend wait debug bits.
468 //
469 // 0x00000100 indicates that the target thread exited before it could
470 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
471 // 0x00080000 each indicate a cancelled suspend request so they don't
472 // count as wait failures either.
473 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
474
475 class TraceSuspendDebugBits : public StackObj {
476 private:
477 JavaThread * jt;
478 bool is_wait;
479 bool called_by_wait; // meaningful when !is_wait
480 uint32_t * bits;
481
482 public:
483 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
484 uint32_t *_bits) {
485 jt = _jt;
486 is_wait = _is_wait;
487 called_by_wait = _called_by_wait;
488 bits = _bits;
489 }
490
491 ~TraceSuspendDebugBits() {
492 if (!is_wait) {
493 #if 1
494 // By default, don't trace bits for is_ext_suspend_completed() calls.
495 // That trace is very chatty.
496 return;
497 #else
498 if (!called_by_wait) {
499 // If tracing for is_ext_suspend_completed() is enabled, then only
500 // trace calls to it from wait_for_ext_suspend_completion()
501 return;
502 }
503 #endif
504 }
505
506 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
507 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
508 MutexLocker ml(Threads_lock); // needed for get_thread_name()
509 ResourceMark rm;
510
511 tty->print_cr(
512 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
513 jt->get_thread_name(), *bits);
514
515 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
516 }
517 }
518 }
519 };
520 #undef DEBUG_FALSE_BITS
521
522
523 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
525
526 bool did_trans_retry = false; // only do thread_in_native_trans retry once
527 bool do_trans_retry; // flag to force the retry
528
529 *bits |= 0x00000001;
530
531 do {
532 do_trans_retry = false;
533
534 if (is_exiting()) {
535 // Thread is in the process of exiting. This is always checked
536 // first to reduce the risk of dereferencing a freed JavaThread.
537 *bits |= 0x00000100;
538 return false;
539 }
540
541 if (!is_external_suspend()) {
542 // Suspend request is cancelled. This is always checked before
543 // is_ext_suspended() to reduce the risk of a rogue resume
544 // confusing the thread that made the suspend request.
545 *bits |= 0x00000200;
546 return false;
547 }
548
549 if (is_ext_suspended()) {
550 // thread is suspended
551 *bits |= 0x00000400;
552 return true;
553 }
554
555 // Now that we no longer do hard suspends of threads running
556 // native code, the target thread can be changing thread state
557 // while we are in this routine:
558 //
559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
560 //
561 // We save a copy of the thread state as observed at this moment
562 // and make our decision about suspend completeness based on the
563 // copy. This closes the race where the thread state is seen as
564 // _thread_in_native_trans in the if-thread_blocked check, but is
565 // seen as _thread_blocked in if-thread_in_native_trans check.
566 JavaThreadState save_state = thread_state();
567
568 if (save_state == _thread_blocked && is_suspend_equivalent()) {
569 // If the thread's state is _thread_blocked and this blocking
570 // condition is known to be equivalent to a suspend, then we can
571 // consider the thread to be externally suspended. This means that
572 // the code that sets _thread_blocked has been modified to do
573 // self-suspension if the blocking condition releases. We also
574 // used to check for CONDVAR_WAIT here, but that is now covered by
575 // the _thread_blocked with self-suspension check.
576 //
577 // Return true since we wouldn't be here unless there was still an
578 // external suspend request.
579 *bits |= 0x00001000;
580 return true;
581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
582 // Threads running native code will self-suspend on native==>VM/Java
583 // transitions. If its stack is walkable (should always be the case
584 // unless this function is called before the actual java_suspend()
585 // call), then the wait is done.
586 *bits |= 0x00002000;
587 return true;
588 } else if (!called_by_wait && !did_trans_retry &&
589 save_state == _thread_in_native_trans &&
590 frame_anchor()->walkable()) {
591 // The thread is transitioning from thread_in_native to another
592 // thread state. check_safepoint_and_suspend_for_native_trans()
593 // will force the thread to self-suspend. If it hasn't gotten
594 // there yet we may have caught the thread in-between the native
595 // code check above and the self-suspend. Lucky us. If we were
596 // called by wait_for_ext_suspend_completion(), then it
597 // will be doing the retries so we don't have to.
598 //
599 // Since we use the saved thread state in the if-statement above,
600 // there is a chance that the thread has already transitioned to
601 // _thread_blocked by the time we get here. In that case, we will
602 // make a single unnecessary pass through the logic below. This
603 // doesn't hurt anything since we still do the trans retry.
604
605 *bits |= 0x00004000;
606
607 // Once the thread leaves thread_in_native_trans for another
608 // thread state, we break out of this retry loop. We shouldn't
609 // need this flag to prevent us from getting back here, but
610 // sometimes paranoia is good.
611 did_trans_retry = true;
612
613 // We wait for the thread to transition to a more usable state.
614 for (int i = 1; i <= SuspendRetryCount; i++) {
615 // We used to do an "os::yield_all(i)" call here with the intention
616 // that yielding would increase on each retry. However, the parameter
617 // is ignored on Linux which means the yield didn't scale up. Waiting
618 // on the SR_lock below provides a much more predictable scale up for
619 // the delay. It also provides a simple/direct point to check for any
620 // safepoint requests from the VMThread
621
622 // temporarily drops SR_lock while doing wait with safepoint check
623 // (if we're a JavaThread - the WatcherThread can also call this)
624 // and increase delay with each retry
625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
626
627 // check the actual thread state instead of what we saved above
628 if (thread_state() != _thread_in_native_trans) {
629 // the thread has transitioned to another thread state so
630 // try all the checks (except this one) one more time.
631 do_trans_retry = true;
632 break;
633 }
634 } // end retry loop
635
636
637 }
638 } while (do_trans_retry);
639
640 *bits |= 0x00000010;
641 return false;
642 }
643
644 //
645 // Wait for an external suspend request to complete (or be cancelled).
646 // Returns true if the thread is externally suspended and false otherwise.
647 //
648 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
649 uint32_t *bits) {
650 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
651 false /* !called_by_wait */, bits);
652
653 // local flag copies to minimize SR_lock hold time
654 bool is_suspended;
655 bool pending;
656 uint32_t reset_bits;
657
658 // set a marker so is_ext_suspend_completed() knows we are the caller
659 *bits |= 0x00010000;
660
661 // We use reset_bits to reinitialize the bits value at the top of
662 // each retry loop. This allows the caller to make use of any
663 // unused bits for their own marking purposes.
664 reset_bits = *bits;
665
666 {
667 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
668 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
669 delay, bits);
670 pending = is_external_suspend();
671 }
672 // must release SR_lock to allow suspension to complete
673
674 if (!pending) {
675 // A cancelled suspend request is the only false return from
676 // is_ext_suspend_completed() that keeps us from entering the
677 // retry loop.
678 *bits |= 0x00020000;
679 return false;
680 }
681
682 if (is_suspended) {
683 *bits |= 0x00040000;
684 return true;
685 }
686
687 for (int i = 1; i <= retries; i++) {
688 *bits = reset_bits; // reinit to only track last retry
689
690 // We used to do an "os::yield_all(i)" call here with the intention
691 // that yielding would increase on each retry. However, the parameter
692 // is ignored on Linux which means the yield didn't scale up. Waiting
693 // on the SR_lock below provides a much more predictable scale up for
694 // the delay. It also provides a simple/direct point to check for any
695 // safepoint requests from the VMThread
696
697 {
698 MutexLocker ml(SR_lock());
699 // wait with safepoint check (if we're a JavaThread - the WatcherThread
700 // can also call this) and increase delay with each retry
701 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
702
703 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
704 delay, bits);
705
706 // It is possible for the external suspend request to be cancelled
707 // (by a resume) before the actual suspend operation is completed.
708 // Refresh our local copy to see if we still need to wait.
709 pending = is_external_suspend();
710 }
711
712 if (!pending) {
713 // A cancelled suspend request is the only false return from
714 // is_ext_suspend_completed() that keeps us from staying in the
715 // retry loop.
716 *bits |= 0x00080000;
717 return false;
718 }
719
720 if (is_suspended) {
721 *bits |= 0x00100000;
722 return true;
723 }
724 } // end retry loop
725
726 // thread did not suspend after all our retries
727 *bits |= 0x00200000;
728 return false;
729 }
730
731 #ifndef PRODUCT
732 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
733
734 // This should not need to be atomic as the only way for simultaneous
735 // updates is via interrupts. Even then this should be rare or non-existant
736 // and we don't care that much anyway.
737
738 int index = _jmp_ring_index;
739 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
740 _jmp_ring[index]._target = (intptr_t) target;
741 _jmp_ring[index]._instruction = (intptr_t) instr;
742 _jmp_ring[index]._file = file;
743 _jmp_ring[index]._line = line;
744 }
745 #endif /* PRODUCT */
746
747 // Called by flat profiler
748 // Callers have already called wait_for_ext_suspend_completion
749 // The assertion for that is currently too complex to put here:
750 bool JavaThread::profile_last_Java_frame(frame* _fr) {
751 bool gotframe = false;
752 // self suspension saves needed state.
753 if (has_last_Java_frame() && _anchor.walkable()) {
754 *_fr = pd_last_frame();
755 gotframe = true;
756 }
757 return gotframe;
758 }
759
760 void Thread::interrupt(Thread* thread) {
761 trace("interrupt", thread);
762 debug_only(check_for_dangling_thread_pointer(thread);)
763 os::interrupt(thread);
764 }
765
766 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
767 trace("is_interrupted", thread);
768 debug_only(check_for_dangling_thread_pointer(thread);)
769 // Note: If clear_interrupted==false, this simply fetches and
770 // returns the value of the field osthread()->interrupted().
771 return os::is_interrupted(thread, clear_interrupted);
772 }
773
774
775 // GC Support
776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
777 jint thread_parity = _oops_do_parity;
778 if (thread_parity != strong_roots_parity) {
779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
780 if (res == thread_parity) {
781 return true;
782 } else {
783 guarantee(res == strong_roots_parity, "Or else what?");
784 assert(SharedHeap::heap()->workers()->active_workers() > 0,
785 "Should only fail when parallel.");
786 return false;
787 }
788 }
789 assert(SharedHeap::heap()->workers()->active_workers() > 0,
790 "Should only fail when parallel.");
791 return false;
792 }
793
794 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
795 active_handles()->oops_do(f);
796 // Do oop for ThreadShadow
797 f->do_oop((oop*)&_pending_exception);
798 handle_area()->oops_do(f);
799 }
800
801 void Thread::nmethods_do(CodeBlobClosure* cf) {
802 // no nmethods in a generic thread...
803 }
804
805 void Thread::print_on(outputStream* st) const {
806 // get_priority assumes osthread initialized
807 if (osthread() != NULL) {
808 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
809 osthread()->print_on(st);
810 }
811 debug_only(if (WizardMode) print_owned_locks_on(st);)
812 }
813
814 // Thread::print_on_error() is called by fatal error handler. Don't use
815 // any lock or allocate memory.
816 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
817 if (is_VM_thread()) st->print("VMThread");
818 else if (is_Compiler_thread()) st->print("CompilerThread");
819 else if (is_Java_thread()) st->print("JavaThread");
820 else if (is_GC_task_thread()) st->print("GCTaskThread");
821 else if (is_Watcher_thread()) st->print("WatcherThread");
822 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
823 else st->print("Thread");
824
825 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
826 _stack_base - _stack_size, _stack_base);
827
828 if (osthread()) {
829 st->print(" [id=%d]", osthread()->thread_id());
830 }
831 }
832
833 #ifdef ASSERT
834 void Thread::print_owned_locks_on(outputStream* st) const {
835 Monitor *cur = _owned_locks;
836 if (cur == NULL) {
837 st->print(" (no locks) ");
838 } else {
839 st->print_cr(" Locks owned:");
840 while(cur) {
841 cur->print_on(st);
842 cur = cur->next();
843 }
844 }
845 }
846
847 static int ref_use_count = 0;
848
849 bool Thread::owns_locks_but_compiled_lock() const {
850 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
851 if (cur != Compile_lock) return true;
852 }
853 return false;
854 }
855
856
857 #endif
858
859 #ifndef PRODUCT
860
861 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
862 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
863 // no threads which allow_vm_block's are held
864 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
865 // Check if current thread is allowed to block at a safepoint
866 if (!(_allow_safepoint_count == 0))
867 fatal("Possible safepoint reached by thread that does not allow it");
868 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
869 fatal("LEAF method calling lock?");
870 }
871
872 #ifdef ASSERT
873 if (potential_vm_operation && is_Java_thread()
874 && !Universe::is_bootstrapping()) {
875 // Make sure we do not hold any locks that the VM thread also uses.
876 // This could potentially lead to deadlocks
877 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
878 // Threads_lock is special, since the safepoint synchronization will not start before this is
879 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
880 // since it is used to transfer control between JavaThreads and the VMThread
881 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
882 if ( (cur->allow_vm_block() &&
883 cur != Threads_lock &&
884 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
885 cur != VMOperationRequest_lock &&
886 cur != VMOperationQueue_lock) ||
887 cur->rank() == Mutex::special) {
888 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
889 }
890 }
891 }
892
893 if (GCALotAtAllSafepoints) {
894 // We could enter a safepoint here and thus have a gc
895 InterfaceSupport::check_gc_alot();
896 }
897 #endif
898 }
899 #endif
900
901 bool Thread::is_in_stack(address adr) const {
902 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
903 address end = os::current_stack_pointer();
904 if (stack_base() >= adr && adr >= end) return true;
905
906 return false;
907 }
908
909
910 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
911 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
912 // used for compilation in the future. If that change is made, the need for these methods
913 // should be revisited, and they should be removed if possible.
914
915 bool Thread::is_lock_owned(address adr) const {
916 return on_local_stack(adr);
917 }
918
919 bool Thread::set_as_starting_thread() {
920 // NOTE: this must be called inside the main thread.
921 return os::create_main_thread((JavaThread*)this);
922 }
923
924 static void initialize_class(Symbol* class_name, TRAPS) {
925 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
926 instanceKlass::cast(klass)->initialize(CHECK);
927 }
928
929
930 // Creates the initial ThreadGroup
931 static Handle create_initial_thread_group(TRAPS) {
932 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
933 instanceKlassHandle klass (THREAD, k);
934
935 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
936 {
937 JavaValue result(T_VOID);
938 JavaCalls::call_special(&result,
939 system_instance,
940 klass,
941 vmSymbols::object_initializer_name(),
942 vmSymbols::void_method_signature(),
943 CHECK_NH);
944 }
945 Universe::set_system_thread_group(system_instance());
946
947 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
948 {
949 JavaValue result(T_VOID);
950 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
951 JavaCalls::call_special(&result,
952 main_instance,
953 klass,
954 vmSymbols::object_initializer_name(),
955 vmSymbols::threadgroup_string_void_signature(),
956 system_instance,
957 string,
958 CHECK_NH);
959 }
960 return main_instance;
961 }
962
963 // Creates the initial Thread
964 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
965 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
966 instanceKlassHandle klass (THREAD, k);
967 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
968
969 java_lang_Thread::set_thread(thread_oop(), thread);
970 java_lang_Thread::set_priority(thread_oop(), NormPriority);
971 thread->set_threadObj(thread_oop());
972
973 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
974
975 JavaValue result(T_VOID);
976 JavaCalls::call_special(&result, thread_oop,
977 klass,
978 vmSymbols::object_initializer_name(),
979 vmSymbols::threadgroup_string_void_signature(),
980 thread_group,
981 string,
982 CHECK_NULL);
983 return thread_oop();
984 }
985
986 static void call_initializeSystemClass(TRAPS) {
987 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
988 instanceKlassHandle klass (THREAD, k);
989
990 JavaValue result(T_VOID);
991 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
992 vmSymbols::void_method_signature(), CHECK);
993 }
994
995 // General purpose hook into Java code, run once when the VM is initialized.
996 // The Java library method itself may be changed independently from the VM.
997 static void call_postVMInitHook(TRAPS) {
998 klassOop k = SystemDictionary::PostVMInitHook_klass();
999 instanceKlassHandle klass (THREAD, k);
1000 if (klass.not_null()) {
1001 JavaValue result(T_VOID);
1002 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1003 vmSymbols::void_method_signature(),
1004 CHECK);
1005 }
1006 }
1007
1008 static void reset_vm_info_property(TRAPS) {
1009 // the vm info string
1010 ResourceMark rm(THREAD);
1011 const char *vm_info = VM_Version::vm_info_string();
1012
1013 // java.lang.System class
1014 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1015 instanceKlassHandle klass (THREAD, k);
1016
1017 // setProperty arguments
1018 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1019 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1020
1021 // return value
1022 JavaValue r(T_OBJECT);
1023
1024 // public static String setProperty(String key, String value);
1025 JavaCalls::call_static(&r,
1026 klass,
1027 vmSymbols::setProperty_name(),
1028 vmSymbols::string_string_string_signature(),
1029 key_str,
1030 value_str,
1031 CHECK);
1032 }
1033
1034
1035 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1036 assert(thread_group.not_null(), "thread group should be specified");
1037 assert(threadObj() == NULL, "should only create Java thread object once");
1038
1039 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1040 instanceKlassHandle klass (THREAD, k);
1041 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1042
1043 java_lang_Thread::set_thread(thread_oop(), this);
1044 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1045 set_threadObj(thread_oop());
1046
1047 JavaValue result(T_VOID);
1048 if (thread_name != NULL) {
1049 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1050 // Thread gets assigned specified name and null target
1051 JavaCalls::call_special(&result,
1052 thread_oop,
1053 klass,
1054 vmSymbols::object_initializer_name(),
1055 vmSymbols::threadgroup_string_void_signature(),
1056 thread_group, // Argument 1
1057 name, // Argument 2
1058 THREAD);
1059 } else {
1060 // Thread gets assigned name "Thread-nnn" and null target
1061 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1062 JavaCalls::call_special(&result,
1063 thread_oop,
1064 klass,
1065 vmSymbols::object_initializer_name(),
1066 vmSymbols::threadgroup_runnable_void_signature(),
1067 thread_group, // Argument 1
1068 Handle(), // Argument 2
1069 THREAD);
1070 }
1071
1072
1073 if (daemon) {
1074 java_lang_Thread::set_daemon(thread_oop());
1075 }
1076
1077 if (HAS_PENDING_EXCEPTION) {
1078 return;
1079 }
1080
1081 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1082 Handle threadObj(this, this->threadObj());
1083
1084 JavaCalls::call_special(&result,
1085 thread_group,
1086 group,
1087 vmSymbols::add_method_name(),
1088 vmSymbols::thread_void_signature(),
1089 threadObj, // Arg 1
1090 THREAD);
1091
1092
1093 }
1094
1095 // NamedThread -- non-JavaThread subclasses with multiple
1096 // uniquely named instances should derive from this.
1097 NamedThread::NamedThread() : Thread() {
1098 _name = NULL;
1099 _processed_thread = NULL;
1100 }
1101
1102 NamedThread::~NamedThread() {
1103 if (_name != NULL) {
1104 FREE_C_HEAP_ARRAY(char, _name);
1105 _name = NULL;
1106 }
1107 }
1108
1109 void NamedThread::set_name(const char* format, ...) {
1110 guarantee(_name == NULL, "Only get to set name once.");
1111 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1112 guarantee(_name != NULL, "alloc failure");
1113 va_list ap;
1114 va_start(ap, format);
1115 jio_vsnprintf(_name, max_name_len, format, ap);
1116 va_end(ap);
1117 }
1118
1119 // ======= WatcherThread ========
1120
1121 // The watcher thread exists to simulate timer interrupts. It should
1122 // be replaced by an abstraction over whatever native support for
1123 // timer interrupts exists on the platform.
1124
1125 WatcherThread* WatcherThread::_watcher_thread = NULL;
1126 volatile bool WatcherThread::_should_terminate = false;
1127
1128 WatcherThread::WatcherThread() : Thread() {
1129 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1130 if (os::create_thread(this, os::watcher_thread)) {
1131 _watcher_thread = this;
1132
1133 // Set the watcher thread to the highest OS priority which should not be
1134 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1135 // is created. The only normal thread using this priority is the reference
1136 // handler thread, which runs for very short intervals only.
1137 // If the VMThread's priority is not lower than the WatcherThread profiling
1138 // will be inaccurate.
1139 os::set_priority(this, MaxPriority);
1140 if (!DisableStartThread) {
1141 os::start_thread(this);
1142 }
1143 }
1144 }
1145
1146 void WatcherThread::run() {
1147 assert(this == watcher_thread(), "just checking");
1148
1149 this->record_stack_base_and_size();
1150 this->initialize_thread_local_storage();
1151 this->set_active_handles(JNIHandleBlock::allocate_block());
1152 while(!_should_terminate) {
1153 assert(watcher_thread() == Thread::current(), "thread consistency check");
1154 assert(watcher_thread() == this, "thread consistency check");
1155
1156 // Calculate how long it'll be until the next PeriodicTask work
1157 // should be done, and sleep that amount of time.
1158 size_t time_to_wait = PeriodicTask::time_to_wait();
1159
1160 // we expect this to timeout - we only ever get unparked when
1161 // we should terminate
1162 {
1163 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1164
1165 jlong prev_time = os::javaTimeNanos();
1166 for (;;) {
1167 int res= _SleepEvent->park(time_to_wait);
1168 if (res == OS_TIMEOUT || _should_terminate)
1169 break;
1170 // spurious wakeup of some kind
1171 jlong now = os::javaTimeNanos();
1172 time_to_wait -= (now - prev_time) / 1000000;
1173 if (time_to_wait <= 0)
1174 break;
1175 prev_time = now;
1176 }
1177 }
1178
1179 if (is_error_reported()) {
1180 // A fatal error has happened, the error handler(VMError::report_and_die)
1181 // should abort JVM after creating an error log file. However in some
1182 // rare cases, the error handler itself might deadlock. Here we try to
1183 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1184 //
1185 // This code is in WatcherThread because WatcherThread wakes up
1186 // periodically so the fatal error handler doesn't need to do anything;
1187 // also because the WatcherThread is less likely to crash than other
1188 // threads.
1189
1190 for (;;) {
1191 if (!ShowMessageBoxOnError
1192 && (OnError == NULL || OnError[0] == '\0')
1193 && Arguments::abort_hook() == NULL) {
1194 os::sleep(this, 2 * 60 * 1000, false);
1195 fdStream err(defaultStream::output_fd());
1196 err.print_raw_cr("# [ timer expired, abort... ]");
1197 // skip atexit/vm_exit/vm_abort hooks
1198 os::die();
1199 }
1200
1201 // Wake up 5 seconds later, the fatal handler may reset OnError or
1202 // ShowMessageBoxOnError when it is ready to abort.
1203 os::sleep(this, 5 * 1000, false);
1204 }
1205 }
1206
1207 PeriodicTask::real_time_tick(time_to_wait);
1208
1209 // If we have no more tasks left due to dynamic disenrollment,
1210 // shut down the thread since we don't currently support dynamic enrollment
1211 if (PeriodicTask::num_tasks() == 0) {
1212 _should_terminate = true;
1213 }
1214 }
1215
1216 // Signal that it is terminated
1217 {
1218 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1219 _watcher_thread = NULL;
1220 Terminator_lock->notify();
1221 }
1222
1223 // Thread destructor usually does this..
1224 ThreadLocalStorage::set_thread(NULL);
1225 }
1226
1227 void WatcherThread::start() {
1228 if (watcher_thread() == NULL) {
1229 _should_terminate = false;
1230 // Create the single instance of WatcherThread
1231 new WatcherThread();
1232 }
1233 }
1234
1235 void WatcherThread::stop() {
1236 // it is ok to take late safepoints here, if needed
1237 MutexLocker mu(Terminator_lock);
1238 _should_terminate = true;
1239 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1240
1241 Thread* watcher = watcher_thread();
1242 if (watcher != NULL)
1243 watcher->_SleepEvent->unpark();
1244
1245 while(watcher_thread() != NULL) {
1246 // This wait should make safepoint checks, wait without a timeout,
1247 // and wait as a suspend-equivalent condition.
1248 //
1249 // Note: If the FlatProfiler is running, then this thread is waiting
1250 // for the WatcherThread to terminate and the WatcherThread, via the
1251 // FlatProfiler task, is waiting for the external suspend request on
1252 // this thread to complete. wait_for_ext_suspend_completion() will
1253 // eventually timeout, but that takes time. Making this wait a
1254 // suspend-equivalent condition solves that timeout problem.
1255 //
1256 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1257 Mutex::_as_suspend_equivalent_flag);
1258 }
1259 }
1260
1261 void WatcherThread::print_on(outputStream* st) const {
1262 st->print("\"%s\" ", name());
1263 Thread::print_on(st);
1264 st->cr();
1265 }
1266
1267 // ======= JavaThread ========
1268
1269 // A JavaThread is a normal Java thread
1270
1271 void JavaThread::initialize() {
1272 // Initialize fields
1273
1274 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1275 set_claimed_par_id(-1);
1276
1277 set_saved_exception_pc(NULL);
1278 set_threadObj(NULL);
1279 _anchor.clear();
1280 set_entry_point(NULL);
1281 set_jni_functions(jni_functions());
1282 set_callee_target(NULL);
1283 set_vm_result(NULL);
1284 set_vm_result_2(NULL);
1285 set_vframe_array_head(NULL);
1286 set_vframe_array_last(NULL);
1287 set_deferred_locals(NULL);
1288 set_deopt_mark(NULL);
1289 set_deopt_nmethod(NULL);
1290 clear_must_deopt_id();
1291 set_monitor_chunks(NULL);
1292 set_next(NULL);
1293 set_thread_state(_thread_new);
1294 _terminated = _not_terminated;
1295 _privileged_stack_top = NULL;
1296 _array_for_gc = NULL;
1297 _suspend_equivalent = false;
1298 _in_deopt_handler = 0;
1299 _doing_unsafe_access = false;
1300 _stack_guard_state = stack_guard_unused;
1301 _exception_oop = NULL;
1302 _exception_pc = 0;
1303 _exception_handler_pc = 0;
1304 _is_method_handle_return = 0;
1305 _jvmti_thread_state= NULL;
1306 _should_post_on_exceptions_flag = JNI_FALSE;
1307 _jvmti_get_loaded_classes_closure = NULL;
1308 _interp_only_mode = 0;
1309 _special_runtime_exit_condition = _no_async_condition;
1310 _pending_async_exception = NULL;
1311 _is_compiling = false;
1312 _thread_stat = NULL;
1313 _thread_stat = new ThreadStatistics();
1314 _blocked_on_compilation = false;
1315 _jni_active_critical = 0;
1316 _do_not_unlock_if_synchronized = false;
1317 _cached_monitor_info = NULL;
1318 _parker = Parker::Allocate(this) ;
1319
1320 #ifndef PRODUCT
1321 _jmp_ring_index = 0;
1322 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1323 record_jump(NULL, NULL, NULL, 0);
1324 }
1325 #endif /* PRODUCT */
1326
1327 set_thread_profiler(NULL);
1328 if (FlatProfiler::is_active()) {
1329 // This is where we would decide to either give each thread it's own profiler
1330 // or use one global one from FlatProfiler,
1331 // or up to some count of the number of profiled threads, etc.
1332 ThreadProfiler* pp = new ThreadProfiler();
1333 pp->engage();
1334 set_thread_profiler(pp);
1335 }
1336
1337 // Setup safepoint state info for this thread
1338 ThreadSafepointState::create(this);
1339
1340 debug_only(_java_call_counter = 0);
1341
1342 // JVMTI PopFrame support
1343 _popframe_condition = popframe_inactive;
1344 _popframe_preserved_args = NULL;
1345 _popframe_preserved_args_size = 0;
1346
1347 pd_initialize();
1348 }
1349
1350 #ifndef SERIALGC
1351 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1352 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1353 #endif // !SERIALGC
1354
1355 JavaThread::JavaThread(bool is_attaching_via_jni) :
1356 Thread()
1357 #ifndef SERIALGC
1358 , _satb_mark_queue(&_satb_mark_queue_set),
1359 _dirty_card_queue(&_dirty_card_queue_set)
1360 #endif // !SERIALGC
1361 {
1362 initialize();
1363 if (is_attaching_via_jni) {
1364 _jni_attach_state = _attaching_via_jni;
1365 } else {
1366 _jni_attach_state = _not_attaching_via_jni;
1367 }
1368 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1369 }
1370
1371 bool JavaThread::reguard_stack(address cur_sp) {
1372 if (_stack_guard_state != stack_guard_yellow_disabled) {
1373 return true; // Stack already guarded or guard pages not needed.
1374 }
1375
1376 if (register_stack_overflow()) {
1377 // For those architectures which have separate register and
1378 // memory stacks, we must check the register stack to see if
1379 // it has overflowed.
1380 return false;
1381 }
1382
1383 // Java code never executes within the yellow zone: the latter is only
1384 // there to provoke an exception during stack banging. If java code
1385 // is executing there, either StackShadowPages should be larger, or
1386 // some exception code in c1, c2 or the interpreter isn't unwinding
1387 // when it should.
1388 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1389
1390 enable_stack_yellow_zone();
1391 return true;
1392 }
1393
1394 bool JavaThread::reguard_stack(void) {
1395 return reguard_stack(os::current_stack_pointer());
1396 }
1397
1398
1399 void JavaThread::block_if_vm_exited() {
1400 if (_terminated == _vm_exited) {
1401 // _vm_exited is set at safepoint, and Threads_lock is never released
1402 // we will block here forever
1403 Threads_lock->lock_without_safepoint_check();
1404 ShouldNotReachHere();
1405 }
1406 }
1407
1408
1409 // Remove this ifdef when C1 is ported to the compiler interface.
1410 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1411
1412 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1413 Thread()
1414 #ifndef SERIALGC
1415 , _satb_mark_queue(&_satb_mark_queue_set),
1416 _dirty_card_queue(&_dirty_card_queue_set)
1417 #endif // !SERIALGC
1418 {
1419 if (TraceThreadEvents) {
1420 tty->print_cr("creating thread %p", this);
1421 }
1422 initialize();
1423 _jni_attach_state = _not_attaching_via_jni;
1424 set_entry_point(entry_point);
1425 // Create the native thread itself.
1426 // %note runtime_23
1427 os::ThreadType thr_type = os::java_thread;
1428 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1429 os::java_thread;
1430 os::create_thread(this, thr_type, stack_sz);
1431
1432 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1433 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1434 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1435 // the exception consists of creating the exception object & initializing it, initialization
1436 // will leave the VM via a JavaCall and then all locks must be unlocked).
1437 //
1438 // The thread is still suspended when we reach here. Thread must be explicit started
1439 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1440 // by calling Threads:add. The reason why this is not done here, is because the thread
1441 // object must be fully initialized (take a look at JVM_Start)
1442 }
1443
1444 JavaThread::~JavaThread() {
1445 if (TraceThreadEvents) {
1446 tty->print_cr("terminate thread %p", this);
1447 }
1448
1449 // JSR166 -- return the parker to the free list
1450 Parker::Release(_parker);
1451 _parker = NULL ;
1452
1453 // Free any remaining previous UnrollBlock
1454 vframeArray* old_array = vframe_array_last();
1455
1456 if (old_array != NULL) {
1457 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1458 old_array->set_unroll_block(NULL);
1459 delete old_info;
1460 delete old_array;
1461 }
1462
1463 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1464 if (deferred != NULL) {
1465 // This can only happen if thread is destroyed before deoptimization occurs.
1466 assert(deferred->length() != 0, "empty array!");
1467 do {
1468 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1469 deferred->remove_at(0);
1470 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1471 delete dlv;
1472 } while (deferred->length() != 0);
1473 delete deferred;
1474 }
1475
1476 // All Java related clean up happens in exit
1477 ThreadSafepointState::destroy(this);
1478 if (_thread_profiler != NULL) delete _thread_profiler;
1479 if (_thread_stat != NULL) delete _thread_stat;
1480 }
1481
1482
1483 // The first routine called by a new Java thread
1484 void JavaThread::run() {
1485 // initialize thread-local alloc buffer related fields
1486 this->initialize_tlab();
1487
1488 // used to test validitity of stack trace backs
1489 this->record_base_of_stack_pointer();
1490
1491 // Record real stack base and size.
1492 this->record_stack_base_and_size();
1493
1494 // Initialize thread local storage; set before calling MutexLocker
1495 this->initialize_thread_local_storage();
1496
1497 this->create_stack_guard_pages();
1498
1499 this->cache_global_variables();
1500
1501 // Thread is now sufficient initialized to be handled by the safepoint code as being
1502 // in the VM. Change thread state from _thread_new to _thread_in_vm
1503 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1504
1505 assert(JavaThread::current() == this, "sanity check");
1506 assert(!Thread::current()->owns_locks(), "sanity check");
1507
1508 DTRACE_THREAD_PROBE(start, this);
1509
1510 // This operation might block. We call that after all safepoint checks for a new thread has
1511 // been completed.
1512 this->set_active_handles(JNIHandleBlock::allocate_block());
1513
1514 if (JvmtiExport::should_post_thread_life()) {
1515 JvmtiExport::post_thread_start(this);
1516 }
1517
1518 EVENT_BEGIN(TraceEventThreadStart, event);
1519 EVENT_COMMIT(event,
1520 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1521
1522 // We call another function to do the rest so we are sure that the stack addresses used
1523 // from there will be lower than the stack base just computed
1524 thread_main_inner();
1525
1526 // Note, thread is no longer valid at this point!
1527 }
1528
1529
1530 void JavaThread::thread_main_inner() {
1531 assert(JavaThread::current() == this, "sanity check");
1532 assert(this->threadObj() != NULL, "just checking");
1533
1534 // Execute thread entry point unless this thread has a pending exception
1535 // or has been stopped before starting.
1536 // Note: Due to JVM_StopThread we can have pending exceptions already!
1537 if (!this->has_pending_exception() &&
1538 !java_lang_Thread::is_stillborn(this->threadObj())) {
1539 {
1540 ResourceMark rm(this);
1541 this->set_native_thread_name(this->get_thread_name());
1542 }
1543 HandleMark hm(this);
1544 this->entry_point()(this, this);
1545 }
1546
1547 DTRACE_THREAD_PROBE(stop, this);
1548
1549 this->exit(false);
1550 delete this;
1551 }
1552
1553
1554 static void ensure_join(JavaThread* thread) {
1555 // We do not need to grap the Threads_lock, since we are operating on ourself.
1556 Handle threadObj(thread, thread->threadObj());
1557 assert(threadObj.not_null(), "java thread object must exist");
1558 ObjectLocker lock(threadObj, thread);
1559 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1560 thread->clear_pending_exception();
1561 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1562 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1563 // Clear the native thread instance - this makes isAlive return false and allows the join()
1564 // to complete once we've done the notify_all below
1565 java_lang_Thread::set_thread(threadObj(), NULL);
1566 lock.notify_all(thread);
1567 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1568 thread->clear_pending_exception();
1569 }
1570
1571
1572 // For any new cleanup additions, please check to see if they need to be applied to
1573 // cleanup_failed_attach_current_thread as well.
1574 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1575 assert(this == JavaThread::current(), "thread consistency check");
1576 if (!InitializeJavaLangSystem) return;
1577
1578 HandleMark hm(this);
1579 Handle uncaught_exception(this, this->pending_exception());
1580 this->clear_pending_exception();
1581 Handle threadObj(this, this->threadObj());
1582 assert(threadObj.not_null(), "Java thread object should be created");
1583
1584 if (get_thread_profiler() != NULL) {
1585 get_thread_profiler()->disengage();
1586 ResourceMark rm;
1587 get_thread_profiler()->print(get_thread_name());
1588 }
1589
1590
1591 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1592 {
1593 EXCEPTION_MARK;
1594
1595 CLEAR_PENDING_EXCEPTION;
1596 }
1597 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1598 // has to be fixed by a runtime query method
1599 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1600 // JSR-166: change call from from ThreadGroup.uncaughtException to
1601 // java.lang.Thread.dispatchUncaughtException
1602 if (uncaught_exception.not_null()) {
1603 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1604 {
1605 EXCEPTION_MARK;
1606 // Check if the method Thread.dispatchUncaughtException() exists. If so
1607 // call it. Otherwise we have an older library without the JSR-166 changes,
1608 // so call ThreadGroup.uncaughtException()
1609 KlassHandle recvrKlass(THREAD, threadObj->klass());
1610 CallInfo callinfo;
1611 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1612 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1613 vmSymbols::dispatchUncaughtException_name(),
1614 vmSymbols::throwable_void_signature(),
1615 KlassHandle(), false, false, THREAD);
1616 CLEAR_PENDING_EXCEPTION;
1617 methodHandle method = callinfo.selected_method();
1618 if (method.not_null()) {
1619 JavaValue result(T_VOID);
1620 JavaCalls::call_virtual(&result,
1621 threadObj, thread_klass,
1622 vmSymbols::dispatchUncaughtException_name(),
1623 vmSymbols::throwable_void_signature(),
1624 uncaught_exception,
1625 THREAD);
1626 } else {
1627 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1628 JavaValue result(T_VOID);
1629 JavaCalls::call_virtual(&result,
1630 group, thread_group,
1631 vmSymbols::uncaughtException_name(),
1632 vmSymbols::thread_throwable_void_signature(),
1633 threadObj, // Arg 1
1634 uncaught_exception, // Arg 2
1635 THREAD);
1636 }
1637 if (HAS_PENDING_EXCEPTION) {
1638 ResourceMark rm(this);
1639 jio_fprintf(defaultStream::error_stream(),
1640 "\nException: %s thrown from the UncaughtExceptionHandler"
1641 " in thread \"%s\"\n",
1642 Klass::cast(pending_exception()->klass())->external_name(),
1643 get_thread_name());
1644 CLEAR_PENDING_EXCEPTION;
1645 }
1646 }
1647 }
1648
1649 // Called before the java thread exit since we want to read info
1650 // from java_lang_Thread object
1651 EVENT_BEGIN(TraceEventThreadEnd, event);
1652 EVENT_COMMIT(event,
1653 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1654
1655 // Call after last event on thread
1656 EVENT_THREAD_EXIT(this);
1657
1658 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1659 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1660 // is deprecated anyhow.
1661 { int count = 3;
1662 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1663 EXCEPTION_MARK;
1664 JavaValue result(T_VOID);
1665 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1666 JavaCalls::call_virtual(&result,
1667 threadObj, thread_klass,
1668 vmSymbols::exit_method_name(),
1669 vmSymbols::void_method_signature(),
1670 THREAD);
1671 CLEAR_PENDING_EXCEPTION;
1672 }
1673 }
1674
1675 // notify JVMTI
1676 if (JvmtiExport::should_post_thread_life()) {
1677 JvmtiExport::post_thread_end(this);
1678 }
1679
1680 // We have notified the agents that we are exiting, before we go on,
1681 // we must check for a pending external suspend request and honor it
1682 // in order to not surprise the thread that made the suspend request.
1683 while (true) {
1684 {
1685 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1686 if (!is_external_suspend()) {
1687 set_terminated(_thread_exiting);
1688 ThreadService::current_thread_exiting(this);
1689 break;
1690 }
1691 // Implied else:
1692 // Things get a little tricky here. We have a pending external
1693 // suspend request, but we are holding the SR_lock so we
1694 // can't just self-suspend. So we temporarily drop the lock
1695 // and then self-suspend.
1696 }
1697
1698 ThreadBlockInVM tbivm(this);
1699 java_suspend_self();
1700
1701 // We're done with this suspend request, but we have to loop around
1702 // and check again. Eventually we will get SR_lock without a pending
1703 // external suspend request and will be able to mark ourselves as
1704 // exiting.
1705 }
1706 // no more external suspends are allowed at this point
1707 } else {
1708 // before_exit() has already posted JVMTI THREAD_END events
1709 }
1710
1711 // Notify waiters on thread object. This has to be done after exit() is called
1712 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1713 // group should have the destroyed bit set before waiters are notified).
1714 ensure_join(this);
1715 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1716
1717 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1718 // held by this thread must be released. A detach operation must only
1719 // get here if there are no Java frames on the stack. Therefore, any
1720 // owned monitors at this point MUST be JNI-acquired monitors which are
1721 // pre-inflated and in the monitor cache.
1722 //
1723 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1724 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1725 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1726 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1727 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1728 }
1729
1730 // These things needs to be done while we are still a Java Thread. Make sure that thread
1731 // is in a consistent state, in case GC happens
1732 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1733
1734 if (active_handles() != NULL) {
1735 JNIHandleBlock* block = active_handles();
1736 set_active_handles(NULL);
1737 JNIHandleBlock::release_block(block);
1738 }
1739
1740 if (free_handle_block() != NULL) {
1741 JNIHandleBlock* block = free_handle_block();
1742 set_free_handle_block(NULL);
1743 JNIHandleBlock::release_block(block);
1744 }
1745
1746 // These have to be removed while this is still a valid thread.
1747 remove_stack_guard_pages();
1748
1749 if (UseTLAB) {
1750 tlab().make_parsable(true); // retire TLAB
1751 }
1752
1753 if (JvmtiEnv::environments_might_exist()) {
1754 JvmtiExport::cleanup_thread(this);
1755 }
1756
1757 #ifndef SERIALGC
1758 // We must flush G1-related buffers before removing a thread from
1759 // the list of active threads.
1760 if (UseG1GC) {
1761 flush_barrier_queues();
1762 }
1763 #endif
1764
1765 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1766 Threads::remove(this);
1767 }
1768
1769 #ifndef SERIALGC
1770 // Flush G1-related queues.
1771 void JavaThread::flush_barrier_queues() {
1772 satb_mark_queue().flush();
1773 dirty_card_queue().flush();
1774 }
1775
1776 void JavaThread::initialize_queues() {
1777 assert(!SafepointSynchronize::is_at_safepoint(),
1778 "we should not be at a safepoint");
1779
1780 ObjPtrQueue& satb_queue = satb_mark_queue();
1781 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1782 // The SATB queue should have been constructed with its active
1783 // field set to false.
1784 assert(!satb_queue.is_active(), "SATB queue should not be active");
1785 assert(satb_queue.is_empty(), "SATB queue should be empty");
1786 // If we are creating the thread during a marking cycle, we should
1787 // set the active field of the SATB queue to true.
1788 if (satb_queue_set.is_active()) {
1789 satb_queue.set_active(true);
1790 }
1791
1792 DirtyCardQueue& dirty_queue = dirty_card_queue();
1793 // The dirty card queue should have been constructed with its
1794 // active field set to true.
1795 assert(dirty_queue.is_active(), "dirty card queue should be active");
1796 }
1797 #endif // !SERIALGC
1798
1799 void JavaThread::cleanup_failed_attach_current_thread() {
1800 if (get_thread_profiler() != NULL) {
1801 get_thread_profiler()->disengage();
1802 ResourceMark rm;
1803 get_thread_profiler()->print(get_thread_name());
1804 }
1805
1806 if (active_handles() != NULL) {
1807 JNIHandleBlock* block = active_handles();
1808 set_active_handles(NULL);
1809 JNIHandleBlock::release_block(block);
1810 }
1811
1812 if (free_handle_block() != NULL) {
1813 JNIHandleBlock* block = free_handle_block();
1814 set_free_handle_block(NULL);
1815 JNIHandleBlock::release_block(block);
1816 }
1817
1818 // These have to be removed while this is still a valid thread.
1819 remove_stack_guard_pages();
1820
1821 if (UseTLAB) {
1822 tlab().make_parsable(true); // retire TLAB, if any
1823 }
1824
1825 #ifndef SERIALGC
1826 if (UseG1GC) {
1827 flush_barrier_queues();
1828 }
1829 #endif
1830
1831 Threads::remove(this);
1832 delete this;
1833 }
1834
1835
1836
1837
1838 JavaThread* JavaThread::active() {
1839 Thread* thread = ThreadLocalStorage::thread();
1840 assert(thread != NULL, "just checking");
1841 if (thread->is_Java_thread()) {
1842 return (JavaThread*) thread;
1843 } else {
1844 assert(thread->is_VM_thread(), "this must be a vm thread");
1845 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1846 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1847 assert(ret->is_Java_thread(), "must be a Java thread");
1848 return ret;
1849 }
1850 }
1851
1852 bool JavaThread::is_lock_owned(address adr) const {
1853 if (Thread::is_lock_owned(adr)) return true;
1854
1855 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1856 if (chunk->contains(adr)) return true;
1857 }
1858
1859 return false;
1860 }
1861
1862
1863 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1864 chunk->set_next(monitor_chunks());
1865 set_monitor_chunks(chunk);
1866 }
1867
1868 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1869 guarantee(monitor_chunks() != NULL, "must be non empty");
1870 if (monitor_chunks() == chunk) {
1871 set_monitor_chunks(chunk->next());
1872 } else {
1873 MonitorChunk* prev = monitor_chunks();
1874 while (prev->next() != chunk) prev = prev->next();
1875 prev->set_next(chunk->next());
1876 }
1877 }
1878
1879 // JVM support.
1880
1881 // Note: this function shouldn't block if it's called in
1882 // _thread_in_native_trans state (such as from
1883 // check_special_condition_for_native_trans()).
1884 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1885
1886 if (has_last_Java_frame() && has_async_condition()) {
1887 // If we are at a polling page safepoint (not a poll return)
1888 // then we must defer async exception because live registers
1889 // will be clobbered by the exception path. Poll return is
1890 // ok because the call we a returning from already collides
1891 // with exception handling registers and so there is no issue.
1892 // (The exception handling path kills call result registers but
1893 // this is ok since the exception kills the result anyway).
1894
1895 if (is_at_poll_safepoint()) {
1896 // if the code we are returning to has deoptimized we must defer
1897 // the exception otherwise live registers get clobbered on the
1898 // exception path before deoptimization is able to retrieve them.
1899 //
1900 RegisterMap map(this, false);
1901 frame caller_fr = last_frame().sender(&map);
1902 assert(caller_fr.is_compiled_frame(), "what?");
1903 if (caller_fr.is_deoptimized_frame()) {
1904 if (TraceExceptions) {
1905 ResourceMark rm;
1906 tty->print_cr("deferred async exception at compiled safepoint");
1907 }
1908 return;
1909 }
1910 }
1911 }
1912
1913 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1914 if (condition == _no_async_condition) {
1915 // Conditions have changed since has_special_runtime_exit_condition()
1916 // was called:
1917 // - if we were here only because of an external suspend request,
1918 // then that was taken care of above (or cancelled) so we are done
1919 // - if we were here because of another async request, then it has
1920 // been cleared between the has_special_runtime_exit_condition()
1921 // and now so again we are done
1922 return;
1923 }
1924
1925 // Check for pending async. exception
1926 if (_pending_async_exception != NULL) {
1927 // Only overwrite an already pending exception, if it is not a threadDeath.
1928 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1929
1930 // We cannot call Exceptions::_throw(...) here because we cannot block
1931 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1932
1933 if (TraceExceptions) {
1934 ResourceMark rm;
1935 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1936 if (has_last_Java_frame() ) {
1937 frame f = last_frame();
1938 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1939 }
1940 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1941 }
1942 _pending_async_exception = NULL;
1943 clear_has_async_exception();
1944 }
1945 }
1946
1947 if (check_unsafe_error &&
1948 condition == _async_unsafe_access_error && !has_pending_exception()) {
1949 condition = _no_async_condition; // done
1950 switch (thread_state()) {
1951 case _thread_in_vm:
1952 {
1953 JavaThread* THREAD = this;
1954 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1955 }
1956 case _thread_in_native:
1957 {
1958 ThreadInVMfromNative tiv(this);
1959 JavaThread* THREAD = this;
1960 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1961 }
1962 case _thread_in_Java:
1963 {
1964 ThreadInVMfromJava tiv(this);
1965 JavaThread* THREAD = this;
1966 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1967 }
1968 default:
1969 ShouldNotReachHere();
1970 }
1971 }
1972
1973 assert(condition == _no_async_condition || has_pending_exception() ||
1974 (!check_unsafe_error && condition == _async_unsafe_access_error),
1975 "must have handled the async condition, if no exception");
1976 }
1977
1978 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1979 //
1980 // Check for pending external suspend. Internal suspend requests do
1981 // not use handle_special_runtime_exit_condition().
1982 // If JNIEnv proxies are allowed, don't self-suspend if the target
1983 // thread is not the current thread. In older versions of jdbx, jdbx
1984 // threads could call into the VM with another thread's JNIEnv so we
1985 // can be here operating on behalf of a suspended thread (4432884).
1986 bool do_self_suspend = is_external_suspend_with_lock();
1987 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1988 //
1989 // Because thread is external suspended the safepoint code will count
1990 // thread as at a safepoint. This can be odd because we can be here
1991 // as _thread_in_Java which would normally transition to _thread_blocked
1992 // at a safepoint. We would like to mark the thread as _thread_blocked
1993 // before calling java_suspend_self like all other callers of it but
1994 // we must then observe proper safepoint protocol. (We can't leave
1995 // _thread_blocked with a safepoint in progress). However we can be
1996 // here as _thread_in_native_trans so we can't use a normal transition
1997 // constructor/destructor pair because they assert on that type of
1998 // transition. We could do something like:
1999 //
2000 // JavaThreadState state = thread_state();
2001 // set_thread_state(_thread_in_vm);
2002 // {
2003 // ThreadBlockInVM tbivm(this);
2004 // java_suspend_self()
2005 // }
2006 // set_thread_state(_thread_in_vm_trans);
2007 // if (safepoint) block;
2008 // set_thread_state(state);
2009 //
2010 // but that is pretty messy. Instead we just go with the way the
2011 // code has worked before and note that this is the only path to
2012 // java_suspend_self that doesn't put the thread in _thread_blocked
2013 // mode.
2014
2015 frame_anchor()->make_walkable(this);
2016 java_suspend_self();
2017
2018 // We might be here for reasons in addition to the self-suspend request
2019 // so check for other async requests.
2020 }
2021
2022 if (check_asyncs) {
2023 check_and_handle_async_exceptions();
2024 }
2025 }
2026
2027 void JavaThread::send_thread_stop(oop java_throwable) {
2028 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2029 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2030 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2031
2032 // Do not throw asynchronous exceptions against the compiler thread
2033 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2034 if (is_Compiler_thread()) return;
2035
2036 {
2037 // Actually throw the Throwable against the target Thread - however
2038 // only if there is no thread death exception installed already.
2039 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2040 // If the topmost frame is a runtime stub, then we are calling into
2041 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2042 // must deoptimize the caller before continuing, as the compiled exception handler table
2043 // may not be valid
2044 if (has_last_Java_frame()) {
2045 frame f = last_frame();
2046 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2047 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2048 RegisterMap reg_map(this, UseBiasedLocking);
2049 frame compiled_frame = f.sender(®_map);
2050 if (compiled_frame.can_be_deoptimized()) {
2051 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2052 }
2053 }
2054 }
2055
2056 // Set async. pending exception in thread.
2057 set_pending_async_exception(java_throwable);
2058
2059 if (TraceExceptions) {
2060 ResourceMark rm;
2061 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2062 }
2063 // for AbortVMOnException flag
2064 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2065 }
2066 }
2067
2068
2069 // Interrupt thread so it will wake up from a potential wait()
2070 Thread::interrupt(this);
2071 }
2072
2073 // External suspension mechanism.
2074 //
2075 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2076 // to any VM_locks and it is at a transition
2077 // Self-suspension will happen on the transition out of the vm.
2078 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2079 //
2080 // Guarantees on return:
2081 // + Target thread will not execute any new bytecode (that's why we need to
2082 // force a safepoint)
2083 // + Target thread will not enter any new monitors
2084 //
2085 void JavaThread::java_suspend() {
2086 { MutexLocker mu(Threads_lock);
2087 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2088 return;
2089 }
2090 }
2091
2092 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2093 if (!is_external_suspend()) {
2094 // a racing resume has cancelled us; bail out now
2095 return;
2096 }
2097
2098 // suspend is done
2099 uint32_t debug_bits = 0;
2100 // Warning: is_ext_suspend_completed() may temporarily drop the
2101 // SR_lock to allow the thread to reach a stable thread state if
2102 // it is currently in a transient thread state.
2103 if (is_ext_suspend_completed(false /* !called_by_wait */,
2104 SuspendRetryDelay, &debug_bits) ) {
2105 return;
2106 }
2107 }
2108
2109 VM_ForceSafepoint vm_suspend;
2110 VMThread::execute(&vm_suspend);
2111 }
2112
2113 // Part II of external suspension.
2114 // A JavaThread self suspends when it detects a pending external suspend
2115 // request. This is usually on transitions. It is also done in places
2116 // where continuing to the next transition would surprise the caller,
2117 // e.g., monitor entry.
2118 //
2119 // Returns the number of times that the thread self-suspended.
2120 //
2121 // Note: DO NOT call java_suspend_self() when you just want to block current
2122 // thread. java_suspend_self() is the second stage of cooperative
2123 // suspension for external suspend requests and should only be used
2124 // to complete an external suspend request.
2125 //
2126 int JavaThread::java_suspend_self() {
2127 int ret = 0;
2128
2129 // we are in the process of exiting so don't suspend
2130 if (is_exiting()) {
2131 clear_external_suspend();
2132 return ret;
2133 }
2134
2135 assert(_anchor.walkable() ||
2136 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2137 "must have walkable stack");
2138
2139 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2140
2141 assert(!this->is_ext_suspended(),
2142 "a thread trying to self-suspend should not already be suspended");
2143
2144 if (this->is_suspend_equivalent()) {
2145 // If we are self-suspending as a result of the lifting of a
2146 // suspend equivalent condition, then the suspend_equivalent
2147 // flag is not cleared until we set the ext_suspended flag so
2148 // that wait_for_ext_suspend_completion() returns consistent
2149 // results.
2150 this->clear_suspend_equivalent();
2151 }
2152
2153 // A racing resume may have cancelled us before we grabbed SR_lock
2154 // above. Or another external suspend request could be waiting for us
2155 // by the time we return from SR_lock()->wait(). The thread
2156 // that requested the suspension may already be trying to walk our
2157 // stack and if we return now, we can change the stack out from under
2158 // it. This would be a "bad thing (TM)" and cause the stack walker
2159 // to crash. We stay self-suspended until there are no more pending
2160 // external suspend requests.
2161 while (is_external_suspend()) {
2162 ret++;
2163 this->set_ext_suspended();
2164
2165 // _ext_suspended flag is cleared by java_resume()
2166 while (is_ext_suspended()) {
2167 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2168 }
2169 }
2170
2171 return ret;
2172 }
2173
2174 #ifdef ASSERT
2175 // verify the JavaThread has not yet been published in the Threads::list, and
2176 // hence doesn't need protection from concurrent access at this stage
2177 void JavaThread::verify_not_published() {
2178 if (!Threads_lock->owned_by_self()) {
2179 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2180 assert( !Threads::includes(this),
2181 "java thread shouldn't have been published yet!");
2182 }
2183 else {
2184 assert( !Threads::includes(this),
2185 "java thread shouldn't have been published yet!");
2186 }
2187 }
2188 #endif
2189
2190 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2191 // progress or when _suspend_flags is non-zero.
2192 // Current thread needs to self-suspend if there is a suspend request and/or
2193 // block if a safepoint is in progress.
2194 // Async exception ISN'T checked.
2195 // Note only the ThreadInVMfromNative transition can call this function
2196 // directly and when thread state is _thread_in_native_trans
2197 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2198 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2199
2200 JavaThread *curJT = JavaThread::current();
2201 bool do_self_suspend = thread->is_external_suspend();
2202
2203 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2204
2205 // If JNIEnv proxies are allowed, don't self-suspend if the target
2206 // thread is not the current thread. In older versions of jdbx, jdbx
2207 // threads could call into the VM with another thread's JNIEnv so we
2208 // can be here operating on behalf of a suspended thread (4432884).
2209 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2210 JavaThreadState state = thread->thread_state();
2211
2212 // We mark this thread_blocked state as a suspend-equivalent so
2213 // that a caller to is_ext_suspend_completed() won't be confused.
2214 // The suspend-equivalent state is cleared by java_suspend_self().
2215 thread->set_suspend_equivalent();
2216
2217 // If the safepoint code sees the _thread_in_native_trans state, it will
2218 // wait until the thread changes to other thread state. There is no
2219 // guarantee on how soon we can obtain the SR_lock and complete the
2220 // self-suspend request. It would be a bad idea to let safepoint wait for
2221 // too long. Temporarily change the state to _thread_blocked to
2222 // let the VM thread know that this thread is ready for GC. The problem
2223 // of changing thread state is that safepoint could happen just after
2224 // java_suspend_self() returns after being resumed, and VM thread will
2225 // see the _thread_blocked state. We must check for safepoint
2226 // after restoring the state and make sure we won't leave while a safepoint
2227 // is in progress.
2228 thread->set_thread_state(_thread_blocked);
2229 thread->java_suspend_self();
2230 thread->set_thread_state(state);
2231 // Make sure new state is seen by VM thread
2232 if (os::is_MP()) {
2233 if (UseMembar) {
2234 // Force a fence between the write above and read below
2235 OrderAccess::fence();
2236 } else {
2237 // Must use this rather than serialization page in particular on Windows
2238 InterfaceSupport::serialize_memory(thread);
2239 }
2240 }
2241 }
2242
2243 if (SafepointSynchronize::do_call_back()) {
2244 // If we are safepointing, then block the caller which may not be
2245 // the same as the target thread (see above).
2246 SafepointSynchronize::block(curJT);
2247 }
2248
2249 if (thread->is_deopt_suspend()) {
2250 thread->clear_deopt_suspend();
2251 RegisterMap map(thread, false);
2252 frame f = thread->last_frame();
2253 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2254 f = f.sender(&map);
2255 }
2256 if (f.id() == thread->must_deopt_id()) {
2257 thread->clear_must_deopt_id();
2258 f.deoptimize(thread);
2259 } else {
2260 fatal("missed deoptimization!");
2261 }
2262 }
2263 }
2264
2265 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2266 // progress or when _suspend_flags is non-zero.
2267 // Current thread needs to self-suspend if there is a suspend request and/or
2268 // block if a safepoint is in progress.
2269 // Also check for pending async exception (not including unsafe access error).
2270 // Note only the native==>VM/Java barriers can call this function and when
2271 // thread state is _thread_in_native_trans.
2272 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2273 check_safepoint_and_suspend_for_native_trans(thread);
2274
2275 if (thread->has_async_exception()) {
2276 // We are in _thread_in_native_trans state, don't handle unsafe
2277 // access error since that may block.
2278 thread->check_and_handle_async_exceptions(false);
2279 }
2280 }
2281
2282 // This is a variant of the normal
2283 // check_special_condition_for_native_trans with slightly different
2284 // semantics for use by critical native wrappers. It does all the
2285 // normal checks but also performs the transition back into
2286 // thread_in_Java state. This is required so that critical natives
2287 // can potentially block and perform a GC if they are the last thread
2288 // exiting the GC_locker.
2289 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2290 check_special_condition_for_native_trans(thread);
2291
2292 // Finish the transition
2293 thread->set_thread_state(_thread_in_Java);
2294
2295 if (thread->do_critical_native_unlock()) {
2296 ThreadInVMfromJavaNoAsyncException tiv(thread);
2297 GC_locker::unlock_critical(thread);
2298 thread->clear_critical_native_unlock();
2299 }
2300 }
2301
2302 // We need to guarantee the Threads_lock here, since resumes are not
2303 // allowed during safepoint synchronization
2304 // Can only resume from an external suspension
2305 void JavaThread::java_resume() {
2306 assert_locked_or_safepoint(Threads_lock);
2307
2308 // Sanity check: thread is gone, has started exiting or the thread
2309 // was not externally suspended.
2310 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2311 return;
2312 }
2313
2314 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2315
2316 clear_external_suspend();
2317
2318 if (is_ext_suspended()) {
2319 clear_ext_suspended();
2320 SR_lock()->notify_all();
2321 }
2322 }
2323
2324 void JavaThread::create_stack_guard_pages() {
2325 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2326 address low_addr = stack_base() - stack_size();
2327 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2328
2329 int allocate = os::allocate_stack_guard_pages();
2330 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2331
2332 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2333 warning("Attempt to allocate stack guard pages failed.");
2334 return;
2335 }
2336
2337 if (os::guard_memory((char *) low_addr, len)) {
2338 _stack_guard_state = stack_guard_enabled;
2339 } else {
2340 warning("Attempt to protect stack guard pages failed.");
2341 if (os::uncommit_memory((char *) low_addr, len)) {
2342 warning("Attempt to deallocate stack guard pages failed.");
2343 }
2344 }
2345 }
2346
2347 void JavaThread::remove_stack_guard_pages() {
2348 if (_stack_guard_state == stack_guard_unused) return;
2349 address low_addr = stack_base() - stack_size();
2350 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2351
2352 if (os::allocate_stack_guard_pages()) {
2353 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2354 _stack_guard_state = stack_guard_unused;
2355 } else {
2356 warning("Attempt to deallocate stack guard pages failed.");
2357 }
2358 } else {
2359 if (_stack_guard_state == stack_guard_unused) return;
2360 if (os::unguard_memory((char *) low_addr, len)) {
2361 _stack_guard_state = stack_guard_unused;
2362 } else {
2363 warning("Attempt to unprotect stack guard pages failed.");
2364 }
2365 }
2366 }
2367
2368 void JavaThread::enable_stack_yellow_zone() {
2369 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2370 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2371
2372 // The base notation is from the stacks point of view, growing downward.
2373 // We need to adjust it to work correctly with guard_memory()
2374 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2375
2376 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2377 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2378
2379 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2380 _stack_guard_state = stack_guard_enabled;
2381 } else {
2382 warning("Attempt to guard stack yellow zone failed.");
2383 }
2384 enable_register_stack_guard();
2385 }
2386
2387 void JavaThread::disable_stack_yellow_zone() {
2388 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2389 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2390
2391 // Simply return if called for a thread that does not use guard pages.
2392 if (_stack_guard_state == stack_guard_unused) return;
2393
2394 // The base notation is from the stacks point of view, growing downward.
2395 // We need to adjust it to work correctly with guard_memory()
2396 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2397
2398 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2399 _stack_guard_state = stack_guard_yellow_disabled;
2400 } else {
2401 warning("Attempt to unguard stack yellow zone failed.");
2402 }
2403 disable_register_stack_guard();
2404 }
2405
2406 void JavaThread::enable_stack_red_zone() {
2407 // The base notation is from the stacks point of view, growing downward.
2408 // We need to adjust it to work correctly with guard_memory()
2409 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2410 address base = stack_red_zone_base() - stack_red_zone_size();
2411
2412 guarantee(base < stack_base(),"Error calculating stack red zone");
2413 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2414
2415 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2416 warning("Attempt to guard stack red zone failed.");
2417 }
2418 }
2419
2420 void JavaThread::disable_stack_red_zone() {
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 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2424 address base = stack_red_zone_base() - stack_red_zone_size();
2425 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2426 warning("Attempt to unguard stack red zone failed.");
2427 }
2428 }
2429
2430 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2431 // ignore is there is no stack
2432 if (!has_last_Java_frame()) return;
2433 // traverse the stack frames. Starts from top frame.
2434 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2435 frame* fr = fst.current();
2436 f(fr, fst.register_map());
2437 }
2438 }
2439
2440
2441 #ifndef PRODUCT
2442 // Deoptimization
2443 // Function for testing deoptimization
2444 void JavaThread::deoptimize() {
2445 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2446 StackFrameStream fst(this, UseBiasedLocking);
2447 bool deopt = false; // Dump stack only if a deopt actually happens.
2448 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2449 // Iterate over all frames in the thread and deoptimize
2450 for(; !fst.is_done(); fst.next()) {
2451 if(fst.current()->can_be_deoptimized()) {
2452
2453 if (only_at) {
2454 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2455 // consists of comma or carriage return separated numbers so
2456 // search for the current bci in that string.
2457 address pc = fst.current()->pc();
2458 nmethod* nm = (nmethod*) fst.current()->cb();
2459 ScopeDesc* sd = nm->scope_desc_at( pc);
2460 char buffer[8];
2461 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2462 size_t len = strlen(buffer);
2463 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2464 while (found != NULL) {
2465 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2466 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2467 // Check that the bci found is bracketed by terminators.
2468 break;
2469 }
2470 found = strstr(found + 1, buffer);
2471 }
2472 if (!found) {
2473 continue;
2474 }
2475 }
2476
2477 if (DebugDeoptimization && !deopt) {
2478 deopt = true; // One-time only print before deopt
2479 tty->print_cr("[BEFORE Deoptimization]");
2480 trace_frames();
2481 trace_stack();
2482 }
2483 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2484 }
2485 }
2486
2487 if (DebugDeoptimization && deopt) {
2488 tty->print_cr("[AFTER Deoptimization]");
2489 trace_frames();
2490 }
2491 }
2492
2493
2494 // Make zombies
2495 void JavaThread::make_zombies() {
2496 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2497 if (fst.current()->can_be_deoptimized()) {
2498 // it is a Java nmethod
2499 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2500 nm->make_not_entrant();
2501 }
2502 }
2503 }
2504 #endif // PRODUCT
2505
2506
2507 void JavaThread::deoptimized_wrt_marked_nmethods() {
2508 if (!has_last_Java_frame()) return;
2509 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2510 StackFrameStream fst(this, UseBiasedLocking);
2511 for(; !fst.is_done(); fst.next()) {
2512 if (fst.current()->should_be_deoptimized()) {
2513 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2514 }
2515 }
2516 }
2517
2518
2519 // GC support
2520 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2521
2522 void JavaThread::gc_epilogue() {
2523 frames_do(frame_gc_epilogue);
2524 }
2525
2526
2527 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2528
2529 void JavaThread::gc_prologue() {
2530 frames_do(frame_gc_prologue);
2531 }
2532
2533 // If the caller is a NamedThread, then remember, in the current scope,
2534 // the given JavaThread in its _processed_thread field.
2535 class RememberProcessedThread: public StackObj {
2536 NamedThread* _cur_thr;
2537 public:
2538 RememberProcessedThread(JavaThread* jthr) {
2539 Thread* thread = Thread::current();
2540 if (thread->is_Named_thread()) {
2541 _cur_thr = (NamedThread *)thread;
2542 _cur_thr->set_processed_thread(jthr);
2543 } else {
2544 _cur_thr = NULL;
2545 }
2546 }
2547
2548 ~RememberProcessedThread() {
2549 if (_cur_thr) {
2550 _cur_thr->set_processed_thread(NULL);
2551 }
2552 }
2553 };
2554
2555 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2556 // Verify that the deferred card marks have been flushed.
2557 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2558
2559 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2560 // since there may be more than one thread using each ThreadProfiler.
2561
2562 // Traverse the GCHandles
2563 Thread::oops_do(f, cf);
2564
2565 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2566 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2567
2568 if (has_last_Java_frame()) {
2569 // Record JavaThread to GC thread
2570 RememberProcessedThread rpt(this);
2571
2572 // Traverse the privileged stack
2573 if (_privileged_stack_top != NULL) {
2574 _privileged_stack_top->oops_do(f);
2575 }
2576
2577 // traverse the registered growable array
2578 if (_array_for_gc != NULL) {
2579 for (int index = 0; index < _array_for_gc->length(); index++) {
2580 f->do_oop(_array_for_gc->adr_at(index));
2581 }
2582 }
2583
2584 // Traverse the monitor chunks
2585 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2586 chunk->oops_do(f);
2587 }
2588
2589 // Traverse the execution stack
2590 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2591 fst.current()->oops_do(f, cf, fst.register_map());
2592 }
2593 }
2594
2595 // callee_target is never live across a gc point so NULL it here should
2596 // it still contain a methdOop.
2597
2598 set_callee_target(NULL);
2599
2600 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2601 // If we have deferred set_locals there might be oops waiting to be
2602 // written
2603 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2604 if (list != NULL) {
2605 for (int i = 0; i < list->length(); i++) {
2606 list->at(i)->oops_do(f);
2607 }
2608 }
2609
2610 // Traverse instance variables at the end since the GC may be moving things
2611 // around using this function
2612 f->do_oop((oop*) &_threadObj);
2613 f->do_oop((oop*) &_vm_result);
2614 f->do_oop((oop*) &_vm_result_2);
2615 f->do_oop((oop*) &_exception_oop);
2616 f->do_oop((oop*) &_pending_async_exception);
2617
2618 if (jvmti_thread_state() != NULL) {
2619 jvmti_thread_state()->oops_do(f);
2620 }
2621 }
2622
2623 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2624 Thread::nmethods_do(cf); // (super method is a no-op)
2625
2626 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2627 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2628
2629 if (has_last_Java_frame()) {
2630 // Traverse the execution stack
2631 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2632 fst.current()->nmethods_do(cf);
2633 }
2634 }
2635 }
2636
2637 // Printing
2638 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2639 switch (_thread_state) {
2640 case _thread_uninitialized: return "_thread_uninitialized";
2641 case _thread_new: return "_thread_new";
2642 case _thread_new_trans: return "_thread_new_trans";
2643 case _thread_in_native: return "_thread_in_native";
2644 case _thread_in_native_trans: return "_thread_in_native_trans";
2645 case _thread_in_vm: return "_thread_in_vm";
2646 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2647 case _thread_in_Java: return "_thread_in_Java";
2648 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2649 case _thread_blocked: return "_thread_blocked";
2650 case _thread_blocked_trans: return "_thread_blocked_trans";
2651 default: return "unknown thread state";
2652 }
2653 }
2654
2655 #ifndef PRODUCT
2656 void JavaThread::print_thread_state_on(outputStream *st) const {
2657 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2658 };
2659 void JavaThread::print_thread_state() const {
2660 print_thread_state_on(tty);
2661 };
2662 #endif // PRODUCT
2663
2664 // Called by Threads::print() for VM_PrintThreads operation
2665 void JavaThread::print_on(outputStream *st) const {
2666 st->print("\"%s\" ", get_thread_name());
2667 oop thread_oop = threadObj();
2668 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2669 Thread::print_on(st);
2670 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2671 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2672 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2673 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2674 }
2675 #ifndef PRODUCT
2676 print_thread_state_on(st);
2677 _safepoint_state->print_on(st);
2678 #endif // PRODUCT
2679 }
2680
2681 // Called by fatal error handler. The difference between this and
2682 // JavaThread::print() is that we can't grab lock or allocate memory.
2683 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2684 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2685 oop thread_obj = threadObj();
2686 if (thread_obj != NULL) {
2687 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2688 }
2689 st->print(" [");
2690 st->print("%s", _get_thread_state_name(_thread_state));
2691 if (osthread()) {
2692 st->print(", id=%d", osthread()->thread_id());
2693 }
2694 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2695 _stack_base - _stack_size, _stack_base);
2696 st->print("]");
2697 return;
2698 }
2699
2700 // Verification
2701
2702 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2703
2704 void JavaThread::verify() {
2705 // Verify oops in the thread.
2706 oops_do(&VerifyOopClosure::verify_oop, NULL);
2707
2708 // Verify the stack frames.
2709 frames_do(frame_verify);
2710 }
2711
2712 // CR 6300358 (sub-CR 2137150)
2713 // Most callers of this method assume that it can't return NULL but a
2714 // thread may not have a name whilst it is in the process of attaching to
2715 // the VM - see CR 6412693, and there are places where a JavaThread can be
2716 // seen prior to having it's threadObj set (eg JNI attaching threads and
2717 // if vm exit occurs during initialization). These cases can all be accounted
2718 // for such that this method never returns NULL.
2719 const char* JavaThread::get_thread_name() const {
2720 #ifdef ASSERT
2721 // early safepoints can hit while current thread does not yet have TLS
2722 if (!SafepointSynchronize::is_at_safepoint()) {
2723 Thread *cur = Thread::current();
2724 if (!(cur->is_Java_thread() && cur == this)) {
2725 // Current JavaThreads are allowed to get their own name without
2726 // the Threads_lock.
2727 assert_locked_or_safepoint(Threads_lock);
2728 }
2729 }
2730 #endif // ASSERT
2731 return get_thread_name_string();
2732 }
2733
2734 // Returns a non-NULL representation of this thread's name, or a suitable
2735 // descriptive string if there is no set name
2736 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2737 const char* name_str;
2738 oop thread_obj = threadObj();
2739 if (thread_obj != NULL) {
2740 typeArrayOop name = java_lang_Thread::name(thread_obj);
2741 if (name != NULL) {
2742 if (buf == NULL) {
2743 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2744 }
2745 else {
2746 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2747 }
2748 }
2749 else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2750 name_str = "<no-name - thread is attaching>";
2751 }
2752 else {
2753 name_str = Thread::name();
2754 }
2755 }
2756 else {
2757 name_str = Thread::name();
2758 }
2759 assert(name_str != NULL, "unexpected NULL thread name");
2760 return name_str;
2761 }
2762
2763
2764 const char* JavaThread::get_threadgroup_name() const {
2765 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2766 oop thread_obj = threadObj();
2767 if (thread_obj != NULL) {
2768 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2769 if (thread_group != NULL) {
2770 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2771 // ThreadGroup.name can be null
2772 if (name != NULL) {
2773 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2774 return str;
2775 }
2776 }
2777 }
2778 return NULL;
2779 }
2780
2781 const char* JavaThread::get_parent_name() const {
2782 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2783 oop thread_obj = threadObj();
2784 if (thread_obj != NULL) {
2785 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2786 if (thread_group != NULL) {
2787 oop parent = java_lang_ThreadGroup::parent(thread_group);
2788 if (parent != NULL) {
2789 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2790 // ThreadGroup.name can be null
2791 if (name != NULL) {
2792 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2793 return str;
2794 }
2795 }
2796 }
2797 }
2798 return NULL;
2799 }
2800
2801 ThreadPriority JavaThread::java_priority() const {
2802 oop thr_oop = threadObj();
2803 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2804 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2805 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2806 return priority;
2807 }
2808
2809 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2810
2811 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2812 // Link Java Thread object <-> C++ Thread
2813
2814 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2815 // and put it into a new Handle. The Handle "thread_oop" can then
2816 // be used to pass the C++ thread object to other methods.
2817
2818 // Set the Java level thread object (jthread) field of the
2819 // new thread (a JavaThread *) to C++ thread object using the
2820 // "thread_oop" handle.
2821
2822 // Set the thread field (a JavaThread *) of the
2823 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2824
2825 Handle thread_oop(Thread::current(),
2826 JNIHandles::resolve_non_null(jni_thread));
2827 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2828 "must be initialized");
2829 set_threadObj(thread_oop());
2830 java_lang_Thread::set_thread(thread_oop(), this);
2831
2832 if (prio == NoPriority) {
2833 prio = java_lang_Thread::priority(thread_oop());
2834 assert(prio != NoPriority, "A valid priority should be present");
2835 }
2836
2837 // Push the Java priority down to the native thread; needs Threads_lock
2838 Thread::set_priority(this, prio);
2839
2840 // Add the new thread to the Threads list and set it in motion.
2841 // We must have threads lock in order to call Threads::add.
2842 // It is crucial that we do not block before the thread is
2843 // added to the Threads list for if a GC happens, then the java_thread oop
2844 // will not be visited by GC.
2845 Threads::add(this);
2846 }
2847
2848 oop JavaThread::current_park_blocker() {
2849 // Support for JSR-166 locks
2850 oop thread_oop = threadObj();
2851 if (thread_oop != NULL &&
2852 JDK_Version::current().supports_thread_park_blocker()) {
2853 return java_lang_Thread::park_blocker(thread_oop);
2854 }
2855 return NULL;
2856 }
2857
2858
2859 void JavaThread::print_stack_on(outputStream* st) {
2860 if (!has_last_Java_frame()) return;
2861 ResourceMark rm;
2862 HandleMark hm;
2863
2864 RegisterMap reg_map(this);
2865 vframe* start_vf = last_java_vframe(®_map);
2866 int count = 0;
2867 for (vframe* f = start_vf; f; f = f->sender() ) {
2868 if (f->is_java_frame()) {
2869 javaVFrame* jvf = javaVFrame::cast(f);
2870 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2871
2872 // Print out lock information
2873 if (JavaMonitorsInStackTrace) {
2874 jvf->print_lock_info_on(st, count);
2875 }
2876 } else {
2877 // Ignore non-Java frames
2878 }
2879
2880 // Bail-out case for too deep stacks
2881 count++;
2882 if (MaxJavaStackTraceDepth == count) return;
2883 }
2884 }
2885
2886
2887 // JVMTI PopFrame support
2888 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2889 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2890 if (in_bytes(size_in_bytes) != 0) {
2891 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2892 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2893 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2894 }
2895 }
2896
2897 void* JavaThread::popframe_preserved_args() {
2898 return _popframe_preserved_args;
2899 }
2900
2901 ByteSize JavaThread::popframe_preserved_args_size() {
2902 return in_ByteSize(_popframe_preserved_args_size);
2903 }
2904
2905 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2906 int sz = in_bytes(popframe_preserved_args_size());
2907 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2908 return in_WordSize(sz / wordSize);
2909 }
2910
2911 void JavaThread::popframe_free_preserved_args() {
2912 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2913 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2914 _popframe_preserved_args = NULL;
2915 _popframe_preserved_args_size = 0;
2916 }
2917
2918 #ifndef PRODUCT
2919
2920 void JavaThread::trace_frames() {
2921 tty->print_cr("[Describe stack]");
2922 int frame_no = 1;
2923 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2924 tty->print(" %d. ", frame_no++);
2925 fst.current()->print_value_on(tty,this);
2926 tty->cr();
2927 }
2928 }
2929
2930 class PrintAndVerifyOopClosure: public OopClosure {
2931 protected:
2932 template <class T> inline void do_oop_work(T* p) {
2933 oop obj = oopDesc::load_decode_heap_oop(p);
2934 if (obj == NULL) return;
2935 tty->print(INTPTR_FORMAT ": ", p);
2936 if (obj->is_oop_or_null()) {
2937 if (obj->is_objArray()) {
2938 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
2939 } else {
2940 obj->print();
2941 }
2942 } else {
2943 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
2944 }
2945 tty->cr();
2946 }
2947 public:
2948 virtual void do_oop(oop* p) { do_oop_work(p); }
2949 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2950 };
2951
2952
2953 static void oops_print(frame* f, const RegisterMap *map) {
2954 PrintAndVerifyOopClosure print;
2955 f->print_value();
2956 f->oops_do(&print, NULL, (RegisterMap*)map);
2957 }
2958
2959 // Print our all the locations that contain oops and whether they are
2960 // valid or not. This useful when trying to find the oldest frame
2961 // where an oop has gone bad since the frame walk is from youngest to
2962 // oldest.
2963 void JavaThread::trace_oops() {
2964 tty->print_cr("[Trace oops]");
2965 frames_do(oops_print);
2966 }
2967
2968
2969 #ifdef ASSERT
2970 // Print or validate the layout of stack frames
2971 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2972 ResourceMark rm;
2973 PRESERVE_EXCEPTION_MARK;
2974 FrameValues values;
2975 int frame_no = 0;
2976 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
2977 fst.current()->describe(values, ++frame_no);
2978 if (depth == frame_no) break;
2979 }
2980 if (validate_only) {
2981 values.validate();
2982 } else {
2983 tty->print_cr("[Describe stack layout]");
2984 values.print(this);
2985 }
2986 }
2987 #endif
2988
2989 void JavaThread::trace_stack_from(vframe* start_vf) {
2990 ResourceMark rm;
2991 int vframe_no = 1;
2992 for (vframe* f = start_vf; f; f = f->sender() ) {
2993 if (f->is_java_frame()) {
2994 javaVFrame::cast(f)->print_activation(vframe_no++);
2995 } else {
2996 f->print();
2997 }
2998 if (vframe_no > StackPrintLimit) {
2999 tty->print_cr("...<more frames>...");
3000 return;
3001 }
3002 }
3003 }
3004
3005
3006 void JavaThread::trace_stack() {
3007 if (!has_last_Java_frame()) return;
3008 ResourceMark rm;
3009 HandleMark hm;
3010 RegisterMap reg_map(this);
3011 trace_stack_from(last_java_vframe(®_map));
3012 }
3013
3014
3015 #endif // PRODUCT
3016
3017
3018 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3019 assert(reg_map != NULL, "a map must be given");
3020 frame f = last_frame();
3021 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3022 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3023 }
3024 return NULL;
3025 }
3026
3027
3028 klassOop JavaThread::security_get_caller_class(int depth) {
3029 vframeStream vfst(this);
3030 vfst.security_get_caller_frame(depth);
3031 if (!vfst.at_end()) {
3032 return vfst.method()->method_holder();
3033 }
3034 return NULL;
3035 }
3036
3037 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3038 assert(thread->is_Compiler_thread(), "must be compiler thread");
3039 CompileBroker::compiler_thread_loop();
3040 }
3041
3042 // Create a CompilerThread
3043 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3044 : JavaThread(&compiler_thread_entry) {
3045 _env = NULL;
3046 _log = NULL;
3047 _task = NULL;
3048 _queue = queue;
3049 _counters = counters;
3050 _buffer_blob = NULL;
3051 _scanned_nmethod = NULL;
3052
3053 #ifndef PRODUCT
3054 _ideal_graph_printer = NULL;
3055 #endif
3056 }
3057
3058 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3059 JavaThread::oops_do(f, cf);
3060 if (_scanned_nmethod != NULL && cf != NULL) {
3061 // Safepoints can occur when the sweeper is scanning an nmethod so
3062 // process it here to make sure it isn't unloaded in the middle of
3063 // a scan.
3064 cf->do_code_blob(_scanned_nmethod);
3065 }
3066 }
3067
3068 // ======= Threads ========
3069
3070 // The Threads class links together all active threads, and provides
3071 // operations over all threads. It is protected by its own Mutex
3072 // lock, which is also used in other contexts to protect thread
3073 // operations from having the thread being operated on from exiting
3074 // and going away unexpectedly (e.g., safepoint synchronization)
3075
3076 JavaThread* Threads::_thread_list = NULL;
3077 int Threads::_number_of_threads = 0;
3078 int Threads::_number_of_non_daemon_threads = 0;
3079 int Threads::_return_code = 0;
3080 size_t JavaThread::_stack_size_at_create = 0;
3081
3082 // All JavaThreads
3083 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3084
3085 void os_stream();
3086
3087 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3088 void Threads::threads_do(ThreadClosure* tc) {
3089 assert_locked_or_safepoint(Threads_lock);
3090 // ALL_JAVA_THREADS iterates through all JavaThreads
3091 ALL_JAVA_THREADS(p) {
3092 tc->do_thread(p);
3093 }
3094 // Someday we could have a table or list of all non-JavaThreads.
3095 // For now, just manually iterate through them.
3096 tc->do_thread(VMThread::vm_thread());
3097 Universe::heap()->gc_threads_do(tc);
3098 WatcherThread *wt = WatcherThread::watcher_thread();
3099 // Strictly speaking, the following NULL check isn't sufficient to make sure
3100 // the data for WatcherThread is still valid upon being examined. However,
3101 // considering that WatchThread terminates when the VM is on the way to
3102 // exit at safepoint, the chance of the above is extremely small. The right
3103 // way to prevent termination of WatcherThread would be to acquire
3104 // Terminator_lock, but we can't do that without violating the lock rank
3105 // checking in some cases.
3106 if (wt != NULL)
3107 tc->do_thread(wt);
3108
3109 // If CompilerThreads ever become non-JavaThreads, add them here
3110 }
3111
3112 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3113
3114 extern void JDK_Version_init();
3115
3116 // Check version
3117 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3118
3119 // Initialize the output stream module
3120 ostream_init();
3121
3122 // Process java launcher properties.
3123 Arguments::process_sun_java_launcher_properties(args);
3124
3125 // Initialize the os module before using TLS
3126 os::init();
3127
3128 // Initialize system properties.
3129 Arguments::init_system_properties();
3130
3131 // So that JDK version can be used as a discrimintor when parsing arguments
3132 JDK_Version_init();
3133
3134 // Update/Initialize System properties after JDK version number is known
3135 Arguments::init_version_specific_system_properties();
3136
3137 // Parse arguments
3138 jint parse_result = Arguments::parse(args);
3139 if (parse_result != JNI_OK) return parse_result;
3140
3141 if (PauseAtStartup) {
3142 os::pause();
3143 }
3144
3145 #ifndef USDT2
3146 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3147 #else /* USDT2 */
3148 HOTSPOT_VM_INIT_BEGIN();
3149 #endif /* USDT2 */
3150
3151 // Record VM creation timing statistics
3152 TraceVmCreationTime create_vm_timer;
3153 create_vm_timer.start();
3154
3155 // Timing (must come after argument parsing)
3156 TraceTime timer("Create VM", TraceStartupTime);
3157
3158 // Initialize the os module after parsing the args
3159 jint os_init_2_result = os::init_2();
3160 if (os_init_2_result != JNI_OK) return os_init_2_result;
3161
3162 // Initialize output stream logging
3163 ostream_init_log();
3164
3165 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3166 // Must be before create_vm_init_agents()
3167 if (Arguments::init_libraries_at_startup()) {
3168 convert_vm_init_libraries_to_agents();
3169 }
3170
3171 // Launch -agentlib/-agentpath and converted -Xrun agents
3172 if (Arguments::init_agents_at_startup()) {
3173 create_vm_init_agents();
3174 }
3175
3176 // Initialize Threads state
3177 _thread_list = NULL;
3178 _number_of_threads = 0;
3179 _number_of_non_daemon_threads = 0;
3180
3181 // Initialize TLS
3182 ThreadLocalStorage::init();
3183
3184 // Initialize global data structures and create system classes in heap
3185 vm_init_globals();
3186
3187 // Attach the main thread to this os thread
3188 JavaThread* main_thread = new JavaThread();
3189 main_thread->set_thread_state(_thread_in_vm);
3190 // must do this before set_active_handles and initialize_thread_local_storage
3191 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3192 // change the stack size recorded here to one based on the java thread
3193 // stacksize. This adjusted size is what is used to figure the placement
3194 // of the guard pages.
3195 main_thread->record_stack_base_and_size();
3196 main_thread->initialize_thread_local_storage();
3197
3198 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3199
3200 if (!main_thread->set_as_starting_thread()) {
3201 vm_shutdown_during_initialization(
3202 "Failed necessary internal allocation. Out of swap space");
3203 delete main_thread;
3204 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3205 return JNI_ENOMEM;
3206 }
3207
3208 // Enable guard page *after* os::create_main_thread(), otherwise it would
3209 // crash Linux VM, see notes in os_linux.cpp.
3210 main_thread->create_stack_guard_pages();
3211
3212 // Initialize Java-Level synchronization subsystem
3213 ObjectMonitor::Initialize() ;
3214
3215 // Initialize global modules
3216 jint status = init_globals();
3217 if (status != JNI_OK) {
3218 delete main_thread;
3219 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3220 return status;
3221 }
3222
3223 // Must be run after init_ft which initializes ft_enabled
3224 if (TRACE_INITIALIZE() != JNI_OK) {
3225 vm_exit_during_initialization("Failed to initialize tracing backend");
3226 }
3227
3228 // Should be done after the heap is fully created
3229 main_thread->cache_global_variables();
3230
3231 HandleMark hm;
3232
3233 { MutexLocker mu(Threads_lock);
3234 Threads::add(main_thread);
3235 }
3236
3237 // Any JVMTI raw monitors entered in onload will transition into
3238 // real raw monitor. VM is setup enough here for raw monitor enter.
3239 JvmtiExport::transition_pending_onload_raw_monitors();
3240
3241 if (VerifyBeforeGC &&
3242 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3243 Universe::heap()->prepare_for_verify();
3244 Universe::verify(); // make sure we're starting with a clean slate
3245 }
3246
3247 // Create the VMThread
3248 { TraceTime timer("Start VMThread", TraceStartupTime);
3249 VMThread::create();
3250 Thread* vmthread = VMThread::vm_thread();
3251
3252 if (!os::create_thread(vmthread, os::vm_thread))
3253 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3254
3255 // Wait for the VM thread to become ready, and VMThread::run to initialize
3256 // Monitors can have spurious returns, must always check another state flag
3257 {
3258 MutexLocker ml(Notify_lock);
3259 os::start_thread(vmthread);
3260 while (vmthread->active_handles() == NULL) {
3261 Notify_lock->wait();
3262 }
3263 }
3264 }
3265
3266 assert (Universe::is_fully_initialized(), "not initialized");
3267 EXCEPTION_MARK;
3268
3269 // At this point, the Universe is initialized, but we have not executed
3270 // any byte code. Now is a good time (the only time) to dump out the
3271 // internal state of the JVM for sharing.
3272
3273 if (DumpSharedSpaces) {
3274 Universe::heap()->preload_and_dump(CHECK_0);
3275 ShouldNotReachHere();
3276 }
3277
3278 // Always call even when there are not JVMTI environments yet, since environments
3279 // may be attached late and JVMTI must track phases of VM execution
3280 JvmtiExport::enter_start_phase();
3281
3282 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3283 JvmtiExport::post_vm_start();
3284
3285 {
3286 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3287
3288 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3289 create_vm_init_libraries();
3290 }
3291
3292 if (InitializeJavaLangString) {
3293 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3294 } else {
3295 warning("java.lang.String not initialized");
3296 }
3297
3298 if (AggressiveOpts) {
3299 {
3300 // Forcibly initialize java/util/HashMap and mutate the private
3301 // static final "frontCacheEnabled" field before we start creating instances
3302 #ifdef ASSERT
3303 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3304 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3305 #endif
3306 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3307 KlassHandle k = KlassHandle(THREAD, k_o);
3308 guarantee(k.not_null(), "Must find java/util/HashMap");
3309 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3310 ik->initialize(CHECK_0);
3311 fieldDescriptor fd;
3312 // Possible we might not find this field; if so, don't break
3313 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3314 k()->java_mirror()->bool_field_put(fd.offset(), true);
3315 }
3316 }
3317
3318 if (UseStringCache) {
3319 // Forcibly initialize java/lang/StringValue and mutate the private
3320 // static final "stringCacheEnabled" field before we start creating instances
3321 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3322 // Possible that StringValue isn't present: if so, silently don't break
3323 if (k_o != NULL) {
3324 KlassHandle k = KlassHandle(THREAD, k_o);
3325 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3326 ik->initialize(CHECK_0);
3327 fieldDescriptor fd;
3328 // Possible we might not find this field: if so, silently don't break
3329 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3330 k()->java_mirror()->bool_field_put(fd.offset(), true);
3331 }
3332 }
3333 }
3334 }
3335
3336 // Initialize java_lang.System (needed before creating the thread)
3337 if (InitializeJavaLangSystem) {
3338 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3339 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3340 Handle thread_group = create_initial_thread_group(CHECK_0);
3341 Universe::set_main_thread_group(thread_group());
3342 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3343 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3344 main_thread->set_threadObj(thread_object);
3345 // Set thread status to running since main thread has
3346 // been started and running.
3347 java_lang_Thread::set_thread_status(thread_object,
3348 java_lang_Thread::RUNNABLE);
3349
3350 // The VM preresolve methods to these classes. Make sure that get initialized
3351 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3352 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3353 // The VM creates & returns objects of this class. Make sure it's initialized.
3354 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3355 call_initializeSystemClass(CHECK_0);
3356 } else {
3357 warning("java.lang.System not initialized");
3358 }
3359
3360 // an instance of OutOfMemory exception has been allocated earlier
3361 if (InitializeJavaLangExceptionsErrors) {
3362 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3363 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3364 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3365 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3366 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3367 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3368 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3369 } else {
3370 warning("java.lang.OutOfMemoryError has not been initialized");
3371 warning("java.lang.NullPointerException has not been initialized");
3372 warning("java.lang.ClassCastException has not been initialized");
3373 warning("java.lang.ArrayStoreException has not been initialized");
3374 warning("java.lang.ArithmeticException has not been initialized");
3375 warning("java.lang.StackOverflowError has not been initialized");
3376 }
3377 }
3378
3379 // See : bugid 4211085.
3380 // Background : the static initializer of java.lang.Compiler tries to read
3381 // property"java.compiler" and read & write property "java.vm.info".
3382 // When a security manager is installed through the command line
3383 // option "-Djava.security.manager", the above properties are not
3384 // readable and the static initializer for java.lang.Compiler fails
3385 // resulting in a NoClassDefFoundError. This can happen in any
3386 // user code which calls methods in java.lang.Compiler.
3387 // Hack : the hack is to pre-load and initialize this class, so that only
3388 // system domains are on the stack when the properties are read.
3389 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3390 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3391 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3392 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3393 // Once that is done, we should remove this hack.
3394 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3395
3396 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3397 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3398 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3399 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3400 // This should also be taken out as soon as 4211383 gets fixed.
3401 reset_vm_info_property(CHECK_0);
3402
3403 quicken_jni_functions();
3404
3405 // Set flag that basic initialization has completed. Used by exceptions and various
3406 // debug stuff, that does not work until all basic classes have been initialized.
3407 set_init_completed();
3408
3409 #ifndef USDT2
3410 HS_DTRACE_PROBE(hotspot, vm__init__end);
3411 #else /* USDT2 */
3412 HOTSPOT_VM_INIT_END();
3413 #endif /* USDT2 */
3414
3415 // record VM initialization completion time
3416 Management::record_vm_init_completed();
3417
3418 // Compute system loader. Note that this has to occur after set_init_completed, since
3419 // valid exceptions may be thrown in the process.
3420 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3421 // set_init_completed has just been called, causing exceptions not to be shortcut
3422 // anymore. We call vm_exit_during_initialization directly instead.
3423 SystemDictionary::compute_java_system_loader(THREAD);
3424 if (HAS_PENDING_EXCEPTION) {
3425 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3426 }
3427
3428 #ifndef SERIALGC
3429 // Support for ConcurrentMarkSweep. This should be cleaned up
3430 // and better encapsulated. The ugly nested if test would go away
3431 // once things are properly refactored. XXX YSR
3432 if (UseConcMarkSweepGC || UseG1GC) {
3433 if (UseConcMarkSweepGC) {
3434 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3435 } else {
3436 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3437 }
3438 if (HAS_PENDING_EXCEPTION) {
3439 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3440 }
3441 }
3442 #endif // SERIALGC
3443
3444 // Always call even when there are not JVMTI environments yet, since environments
3445 // may be attached late and JVMTI must track phases of VM execution
3446 JvmtiExport::enter_live_phase();
3447
3448 // Signal Dispatcher needs to be started before VMInit event is posted
3449 os::signal_init();
3450
3451 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3452 if (!DisableAttachMechanism) {
3453 if (StartAttachListener || AttachListener::init_at_startup()) {
3454 AttachListener::init();
3455 }
3456 }
3457
3458 // Launch -Xrun agents
3459 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3460 // back-end can launch with -Xdebug -Xrunjdwp.
3461 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3462 create_vm_init_libraries();
3463 }
3464
3465 if (!TRACE_START()) {
3466 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3467 }
3468
3469 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3470 JvmtiExport::post_vm_initialized();
3471
3472 if (CleanChunkPoolAsync) {
3473 Chunk::start_chunk_pool_cleaner_task();
3474 }
3475
3476 // initialize compiler(s)
3477 CompileBroker::compilation_init();
3478
3479 Management::initialize(THREAD);
3480 if (HAS_PENDING_EXCEPTION) {
3481 // management agent fails to start possibly due to
3482 // configuration problem and is responsible for printing
3483 // stack trace if appropriate. Simply exit VM.
3484 vm_exit(1);
3485 }
3486
3487 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3488 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3489 if (MemProfiling) MemProfiler::engage();
3490 StatSampler::engage();
3491 if (CheckJNICalls) JniPeriodicChecker::engage();
3492
3493 BiasedLocking::init();
3494
3495 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3496 call_postVMInitHook(THREAD);
3497 // The Java side of PostVMInitHook.run must deal with all
3498 // exceptions and provide means of diagnosis.
3499 if (HAS_PENDING_EXCEPTION) {
3500 CLEAR_PENDING_EXCEPTION;
3501 }
3502 }
3503
3504 // Start up the WatcherThread if there are any periodic tasks
3505 // NOTE: All PeriodicTasks should be registered by now. If they
3506 // aren't, late joiners might appear to start slowly (we might
3507 // take a while to process their first tick).
3508 if (PeriodicTask::num_tasks() > 0) {
3509 WatcherThread::start();
3510 }
3511
3512 // Give os specific code one last chance to start
3513 os::init_3();
3514
3515 create_vm_timer.end();
3516 return JNI_OK;
3517 }
3518
3519 // type for the Agent_OnLoad and JVM_OnLoad entry points
3520 extern "C" {
3521 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3522 }
3523 // Find a command line agent library and return its entry point for
3524 // -agentlib: -agentpath: -Xrun
3525 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3526 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3527 OnLoadEntry_t on_load_entry = NULL;
3528 void *library = agent->os_lib(); // check if we have looked it up before
3529
3530 if (library == NULL) {
3531 char buffer[JVM_MAXPATHLEN];
3532 char ebuf[1024];
3533 const char *name = agent->name();
3534 const char *msg = "Could not find agent library ";
3535
3536 if (agent->is_absolute_path()) {
3537 library = os::dll_load(name, ebuf, sizeof ebuf);
3538 if (library == NULL) {
3539 const char *sub_msg = " in absolute path, with error: ";
3540 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3541 char *buf = NEW_C_HEAP_ARRAY(char, len);
3542 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3543 // If we can't find the agent, exit.
3544 vm_exit_during_initialization(buf, NULL);
3545 FREE_C_HEAP_ARRAY(char, buf);
3546 }
3547 } else {
3548 // Try to load the agent from the standard dll directory
3549 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3550 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3551 #ifdef KERNEL
3552 // Download instrument dll
3553 if (library == NULL && strcmp(name, "instrument") == 0) {
3554 char *props = Arguments::get_kernel_properties();
3555 char *home = Arguments::get_java_home();
3556 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3557 " sun.jkernel.DownloadManager -download client_jvm";
3558 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3559 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3560 jio_snprintf(cmd, length, fmt, home, props);
3561 int status = os::fork_and_exec(cmd);
3562 FreeHeap(props);
3563 if (status == -1) {
3564 warning(cmd);
3565 vm_exit_during_initialization("fork_and_exec failed: %s",
3566 strerror(errno));
3567 }
3568 FREE_C_HEAP_ARRAY(char, cmd);
3569 // when this comes back the instrument.dll should be where it belongs.
3570 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3571 }
3572 #endif // KERNEL
3573 if (library == NULL) { // Try the local directory
3574 char ns[1] = {0};
3575 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3576 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3577 if (library == NULL) {
3578 const char *sub_msg = " on the library path, with error: ";
3579 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3580 char *buf = NEW_C_HEAP_ARRAY(char, len);
3581 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3582 // If we can't find the agent, exit.
3583 vm_exit_during_initialization(buf, NULL);
3584 FREE_C_HEAP_ARRAY(char, buf);
3585 }
3586 }
3587 }
3588 agent->set_os_lib(library);
3589 }
3590
3591 // Find the OnLoad function.
3592 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3593 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3594 if (on_load_entry != NULL) break;
3595 }
3596 return on_load_entry;
3597 }
3598
3599 // Find the JVM_OnLoad entry point
3600 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3601 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3602 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3603 }
3604
3605 // Find the Agent_OnLoad entry point
3606 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3607 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3608 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3609 }
3610
3611 // For backwards compatibility with -Xrun
3612 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3613 // treated like -agentpath:
3614 // Must be called before agent libraries are created
3615 void Threads::convert_vm_init_libraries_to_agents() {
3616 AgentLibrary* agent;
3617 AgentLibrary* next;
3618
3619 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3620 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3621 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3622
3623 // If there is an JVM_OnLoad function it will get called later,
3624 // otherwise see if there is an Agent_OnLoad
3625 if (on_load_entry == NULL) {
3626 on_load_entry = lookup_agent_on_load(agent);
3627 if (on_load_entry != NULL) {
3628 // switch it to the agent list -- so that Agent_OnLoad will be called,
3629 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3630 Arguments::convert_library_to_agent(agent);
3631 } else {
3632 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3633 }
3634 }
3635 }
3636 }
3637
3638 // Create agents for -agentlib: -agentpath: and converted -Xrun
3639 // Invokes Agent_OnLoad
3640 // Called very early -- before JavaThreads exist
3641 void Threads::create_vm_init_agents() {
3642 extern struct JavaVM_ main_vm;
3643 AgentLibrary* agent;
3644
3645 JvmtiExport::enter_onload_phase();
3646 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3647 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3648
3649 if (on_load_entry != NULL) {
3650 // Invoke the Agent_OnLoad function
3651 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3652 if (err != JNI_OK) {
3653 vm_exit_during_initialization("agent library failed to init", agent->name());
3654 }
3655 } else {
3656 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3657 }
3658 }
3659 JvmtiExport::enter_primordial_phase();
3660 }
3661
3662 extern "C" {
3663 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3664 }
3665
3666 void Threads::shutdown_vm_agents() {
3667 // Send any Agent_OnUnload notifications
3668 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3669 extern struct JavaVM_ main_vm;
3670 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3671
3672 // Find the Agent_OnUnload function.
3673 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3674 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3675 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3676
3677 // Invoke the Agent_OnUnload function
3678 if (unload_entry != NULL) {
3679 JavaThread* thread = JavaThread::current();
3680 ThreadToNativeFromVM ttn(thread);
3681 HandleMark hm(thread);
3682 (*unload_entry)(&main_vm);
3683 break;
3684 }
3685 }
3686 }
3687 }
3688
3689 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3690 // Invokes JVM_OnLoad
3691 void Threads::create_vm_init_libraries() {
3692 extern struct JavaVM_ main_vm;
3693 AgentLibrary* agent;
3694
3695 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3696 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3697
3698 if (on_load_entry != NULL) {
3699 // Invoke the JVM_OnLoad function
3700 JavaThread* thread = JavaThread::current();
3701 ThreadToNativeFromVM ttn(thread);
3702 HandleMark hm(thread);
3703 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3704 if (err != JNI_OK) {
3705 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3706 }
3707 } else {
3708 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3709 }
3710 }
3711 }
3712
3713 // Last thread running calls java.lang.Shutdown.shutdown()
3714 void JavaThread::invoke_shutdown_hooks() {
3715 HandleMark hm(this);
3716
3717 // We could get here with a pending exception, if so clear it now.
3718 if (this->has_pending_exception()) {
3719 this->clear_pending_exception();
3720 }
3721
3722 EXCEPTION_MARK;
3723 klassOop k =
3724 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3725 THREAD);
3726 if (k != NULL) {
3727 // SystemDictionary::resolve_or_null will return null if there was
3728 // an exception. If we cannot load the Shutdown class, just don't
3729 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3730 // and finalizers (if runFinalizersOnExit is set) won't be run.
3731 // Note that if a shutdown hook was registered or runFinalizersOnExit
3732 // was called, the Shutdown class would have already been loaded
3733 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3734 instanceKlassHandle shutdown_klass (THREAD, k);
3735 JavaValue result(T_VOID);
3736 JavaCalls::call_static(&result,
3737 shutdown_klass,
3738 vmSymbols::shutdown_method_name(),
3739 vmSymbols::void_method_signature(),
3740 THREAD);
3741 }
3742 CLEAR_PENDING_EXCEPTION;
3743 }
3744
3745 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3746 // the program falls off the end of main(). Another VM exit path is through
3747 // vm_exit() when the program calls System.exit() to return a value or when
3748 // there is a serious error in VM. The two shutdown paths are not exactly
3749 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3750 // and VM_Exit op at VM level.
3751 //
3752 // Shutdown sequence:
3753 // + Wait until we are the last non-daemon thread to execute
3754 // <-- every thing is still working at this moment -->
3755 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3756 // shutdown hooks, run finalizers if finalization-on-exit
3757 // + Call before_exit(), prepare for VM exit
3758 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3759 // currently the only user of this mechanism is File.deleteOnExit())
3760 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3761 // post thread end and vm death events to JVMTI,
3762 // stop signal thread
3763 // + Call JavaThread::exit(), it will:
3764 // > release JNI handle blocks, remove stack guard pages
3765 // > remove this thread from Threads list
3766 // <-- no more Java code from this thread after this point -->
3767 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3768 // the compiler threads at safepoint
3769 // <-- do not use anything that could get blocked by Safepoint -->
3770 // + Disable tracing at JNI/JVM barriers
3771 // + Set _vm_exited flag for threads that are still running native code
3772 // + Delete this thread
3773 // + Call exit_globals()
3774 // > deletes tty
3775 // > deletes PerfMemory resources
3776 // + Return to caller
3777
3778 bool Threads::destroy_vm() {
3779 JavaThread* thread = JavaThread::current();
3780
3781 // Wait until we are the last non-daemon thread to execute
3782 { MutexLocker nu(Threads_lock);
3783 while (Threads::number_of_non_daemon_threads() > 1 )
3784 // This wait should make safepoint checks, wait without a timeout,
3785 // and wait as a suspend-equivalent condition.
3786 //
3787 // Note: If the FlatProfiler is running and this thread is waiting
3788 // for another non-daemon thread to finish, then the FlatProfiler
3789 // is waiting for the external suspend request on this thread to
3790 // complete. wait_for_ext_suspend_completion() will eventually
3791 // timeout, but that takes time. Making this wait a suspend-
3792 // equivalent condition solves that timeout problem.
3793 //
3794 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3795 Mutex::_as_suspend_equivalent_flag);
3796 }
3797
3798 // Hang forever on exit if we are reporting an error.
3799 if (ShowMessageBoxOnError && is_error_reported()) {
3800 os::infinite_sleep();
3801 }
3802 os::wait_for_keypress_at_exit();
3803
3804 if (JDK_Version::is_jdk12x_version()) {
3805 // We are the last thread running, so check if finalizers should be run.
3806 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3807 HandleMark rm(thread);
3808 Universe::run_finalizers_on_exit();
3809 } else {
3810 // run Java level shutdown hooks
3811 thread->invoke_shutdown_hooks();
3812 }
3813
3814 before_exit(thread);
3815
3816 thread->exit(true);
3817
3818 // Stop VM thread.
3819 {
3820 // 4945125 The vm thread comes to a safepoint during exit.
3821 // GC vm_operations can get caught at the safepoint, and the
3822 // heap is unparseable if they are caught. Grab the Heap_lock
3823 // to prevent this. The GC vm_operations will not be able to
3824 // queue until after the vm thread is dead.
3825 // After this point, we'll never emerge out of the safepoint before
3826 // the VM exits, so concurrent GC threads do not need to be explicitly
3827 // stopped; they remain inactive until the process exits.
3828 // Note: some concurrent G1 threads may be running during a safepoint,
3829 // but these will not be accessing the heap, just some G1-specific side
3830 // data structures that are not accessed by any other threads but them
3831 // after this point in a terminal safepoint.
3832
3833 MutexLocker ml(Heap_lock);
3834
3835 VMThread::wait_for_vm_thread_exit();
3836 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3837 VMThread::destroy();
3838 }
3839
3840 // clean up ideal graph printers
3841 #if defined(COMPILER2) && !defined(PRODUCT)
3842 IdealGraphPrinter::clean_up();
3843 #endif
3844
3845 // Now, all Java threads are gone except daemon threads. Daemon threads
3846 // running Java code or in VM are stopped by the Safepoint. However,
3847 // daemon threads executing native code are still running. But they
3848 // will be stopped at native=>Java/VM barriers. Note that we can't
3849 // simply kill or suspend them, as it is inherently deadlock-prone.
3850
3851 #ifndef PRODUCT
3852 // disable function tracing at JNI/JVM barriers
3853 TraceJNICalls = false;
3854 TraceJVMCalls = false;
3855 TraceRuntimeCalls = false;
3856 #endif
3857
3858 VM_Exit::set_vm_exited();
3859
3860 notify_vm_shutdown();
3861
3862 delete thread;
3863
3864 // exit_globals() will delete tty
3865 exit_globals();
3866
3867 return true;
3868 }
3869
3870
3871 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3872 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3873 return is_supported_jni_version(version);
3874 }
3875
3876
3877 jboolean Threads::is_supported_jni_version(jint version) {
3878 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3879 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3880 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3881 return JNI_FALSE;
3882 }
3883
3884
3885 void Threads::add(JavaThread* p, bool force_daemon) {
3886 // The threads lock must be owned at this point
3887 assert_locked_or_safepoint(Threads_lock);
3888
3889 // See the comment for this method in thread.hpp for its purpose and
3890 // why it is called here.
3891 p->initialize_queues();
3892 p->set_next(_thread_list);
3893 _thread_list = p;
3894 _number_of_threads++;
3895 oop threadObj = p->threadObj();
3896 bool daemon = true;
3897 // Bootstrapping problem: threadObj can be null for initial
3898 // JavaThread (or for threads attached via JNI)
3899 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3900 _number_of_non_daemon_threads++;
3901 daemon = false;
3902 }
3903
3904 ThreadService::add_thread(p, daemon);
3905
3906 // Possible GC point.
3907 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3908 }
3909
3910 void Threads::remove(JavaThread* p) {
3911 // Extra scope needed for Thread_lock, so we can check
3912 // that we do not remove thread without safepoint code notice
3913 { MutexLocker ml(Threads_lock);
3914
3915 assert(includes(p), "p must be present");
3916
3917 JavaThread* current = _thread_list;
3918 JavaThread* prev = NULL;
3919
3920 while (current != p) {
3921 prev = current;
3922 current = current->next();
3923 }
3924
3925 if (prev) {
3926 prev->set_next(current->next());
3927 } else {
3928 _thread_list = p->next();
3929 }
3930 _number_of_threads--;
3931 oop threadObj = p->threadObj();
3932 bool daemon = true;
3933 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3934 _number_of_non_daemon_threads--;
3935 daemon = false;
3936
3937 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3938 // on destroy_vm will wake up.
3939 if (number_of_non_daemon_threads() == 1)
3940 Threads_lock->notify_all();
3941 }
3942 ThreadService::remove_thread(p, daemon);
3943
3944 // Make sure that safepoint code disregard this thread. This is needed since
3945 // the thread might mess around with locks after this point. This can cause it
3946 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3947 // of this thread since it is removed from the queue.
3948 p->set_terminated_value();
3949 } // unlock Threads_lock
3950
3951 // Since Events::log uses a lock, we grab it outside the Threads_lock
3952 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
3953 }
3954
3955 // Threads_lock must be held when this is called (or must be called during a safepoint)
3956 bool Threads::includes(JavaThread* p) {
3957 assert(Threads_lock->is_locked(), "sanity check");
3958 ALL_JAVA_THREADS(q) {
3959 if (q == p ) {
3960 return true;
3961 }
3962 }
3963 return false;
3964 }
3965
3966 // Operations on the Threads list for GC. These are not explicitly locked,
3967 // but the garbage collector must provide a safe context for them to run.
3968 // In particular, these things should never be called when the Threads_lock
3969 // is held by some other thread. (Note: the Safepoint abstraction also
3970 // uses the Threads_lock to gurantee this property. It also makes sure that
3971 // all threads gets blocked when exiting or starting).
3972
3973 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3974 ALL_JAVA_THREADS(p) {
3975 p->oops_do(f, cf);
3976 }
3977 VMThread::vm_thread()->oops_do(f, cf);
3978 }
3979
3980 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3981 // Introduce a mechanism allowing parallel threads to claim threads as
3982 // root groups. Overhead should be small enough to use all the time,
3983 // even in sequential code.
3984 SharedHeap* sh = SharedHeap::heap();
3985 // Cannot yet substitute active_workers for n_par_threads
3986 // because of G1CollectedHeap::verify() use of
3987 // SharedHeap::process_strong_roots(). n_par_threads == 0 will
3988 // turn off parallelism in process_strong_roots while active_workers
3989 // is being used for parallelism elsewhere.
3990 bool is_par = sh->n_par_threads() > 0;
3991 assert(!is_par ||
3992 (SharedHeap::heap()->n_par_threads() ==
3993 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
3994 int cp = SharedHeap::heap()->strong_roots_parity();
3995 ALL_JAVA_THREADS(p) {
3996 if (p->claim_oops_do(is_par, cp)) {
3997 p->oops_do(f, cf);
3998 }
3999 }
4000 VMThread* vmt = VMThread::vm_thread();
4001 if (vmt->claim_oops_do(is_par, cp)) {
4002 vmt->oops_do(f, cf);
4003 }
4004 }
4005
4006 #ifndef SERIALGC
4007 // Used by ParallelScavenge
4008 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4009 ALL_JAVA_THREADS(p) {
4010 q->enqueue(new ThreadRootsTask(p));
4011 }
4012 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4013 }
4014
4015 // Used by Parallel Old
4016 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4017 ALL_JAVA_THREADS(p) {
4018 q->enqueue(new ThreadRootsMarkingTask(p));
4019 }
4020 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4021 }
4022 #endif // SERIALGC
4023
4024 void Threads::nmethods_do(CodeBlobClosure* cf) {
4025 ALL_JAVA_THREADS(p) {
4026 p->nmethods_do(cf);
4027 }
4028 VMThread::vm_thread()->nmethods_do(cf);
4029 }
4030
4031 void Threads::gc_epilogue() {
4032 ALL_JAVA_THREADS(p) {
4033 p->gc_epilogue();
4034 }
4035 }
4036
4037 void Threads::gc_prologue() {
4038 ALL_JAVA_THREADS(p) {
4039 p->gc_prologue();
4040 }
4041 }
4042
4043 void Threads::deoptimized_wrt_marked_nmethods() {
4044 ALL_JAVA_THREADS(p) {
4045 p->deoptimized_wrt_marked_nmethods();
4046 }
4047 }
4048
4049
4050 // Get count Java threads that are waiting to enter the specified monitor.
4051 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4052 address monitor, bool doLock) {
4053 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4054 "must grab Threads_lock or be at safepoint");
4055 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4056
4057 int i = 0;
4058 {
4059 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4060 ALL_JAVA_THREADS(p) {
4061 if (p->is_Compiler_thread()) continue;
4062
4063 address pending = (address)p->current_pending_monitor();
4064 if (pending == monitor) { // found a match
4065 if (i < count) result->append(p); // save the first count matches
4066 i++;
4067 }
4068 }
4069 }
4070 return result;
4071 }
4072
4073
4074 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4075 assert(doLock ||
4076 Threads_lock->owned_by_self() ||
4077 SafepointSynchronize::is_at_safepoint(),
4078 "must grab Threads_lock or be at safepoint");
4079
4080 // NULL owner means not locked so we can skip the search
4081 if (owner == NULL) return NULL;
4082
4083 {
4084 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4085 ALL_JAVA_THREADS(p) {
4086 // first, see if owner is the address of a Java thread
4087 if (owner == (address)p) return p;
4088 }
4089 }
4090 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
4091 if (UseHeavyMonitors) return NULL;
4092
4093 //
4094 // If we didn't find a matching Java thread and we didn't force use of
4095 // heavyweight monitors, then the owner is the stack address of the
4096 // Lock Word in the owning Java thread's stack.
4097 //
4098 JavaThread* the_owner = NULL;
4099 {
4100 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4101 ALL_JAVA_THREADS(q) {
4102 if (q->is_lock_owned(owner)) {
4103 the_owner = q;
4104 break;
4105 }
4106 }
4107 }
4108 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
4109 return the_owner;
4110 }
4111
4112 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4113 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4114 char buf[32];
4115 st->print_cr(os::local_time_string(buf, sizeof(buf)));
4116
4117 st->print_cr("Full thread dump %s (%s %s):",
4118 Abstract_VM_Version::vm_name(),
4119 Abstract_VM_Version::vm_release(),
4120 Abstract_VM_Version::vm_info_string()
4121 );
4122 st->cr();
4123
4124 #ifndef SERIALGC
4125 // Dump concurrent locks
4126 ConcurrentLocksDump concurrent_locks;
4127 if (print_concurrent_locks) {
4128 concurrent_locks.dump_at_safepoint();
4129 }
4130 #endif // SERIALGC
4131
4132 ALL_JAVA_THREADS(p) {
4133 ResourceMark rm;
4134 p->print_on(st);
4135 if (print_stacks) {
4136 if (internal_format) {
4137 p->trace_stack();
4138 } else {
4139 p->print_stack_on(st);
4140 }
4141 }
4142 st->cr();
4143 #ifndef SERIALGC
4144 if (print_concurrent_locks) {
4145 concurrent_locks.print_locks_on(p, st);
4146 }
4147 #endif // SERIALGC
4148 }
4149
4150 VMThread::vm_thread()->print_on(st);
4151 st->cr();
4152 Universe::heap()->print_gc_threads_on(st);
4153 WatcherThread* wt = WatcherThread::watcher_thread();
4154 if (wt != NULL) wt->print_on(st);
4155 st->cr();
4156 CompileBroker::print_compiler_threads_on(st);
4157 st->flush();
4158 }
4159
4160 // Threads::print_on_error() is called by fatal error handler. It's possible
4161 // that VM is not at safepoint and/or current thread is inside signal handler.
4162 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4163 // memory (even in resource area), it might deadlock the error handler.
4164 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4165 bool found_current = false;
4166 st->print_cr("Java Threads: ( => current thread )");
4167 ALL_JAVA_THREADS(thread) {
4168 bool is_current = (current == thread);
4169 found_current = found_current || is_current;
4170
4171 st->print("%s", is_current ? "=>" : " ");
4172
4173 st->print(PTR_FORMAT, thread);
4174 st->print(" ");
4175 thread->print_on_error(st, buf, buflen);
4176 st->cr();
4177 }
4178 st->cr();
4179
4180 st->print_cr("Other Threads:");
4181 if (VMThread::vm_thread()) {
4182 bool is_current = (current == VMThread::vm_thread());
4183 found_current = found_current || is_current;
4184 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4185
4186 st->print(PTR_FORMAT, VMThread::vm_thread());
4187 st->print(" ");
4188 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4189 st->cr();
4190 }
4191 WatcherThread* wt = WatcherThread::watcher_thread();
4192 if (wt != NULL) {
4193 bool is_current = (current == wt);
4194 found_current = found_current || is_current;
4195 st->print("%s", is_current ? "=>" : " ");
4196
4197 st->print(PTR_FORMAT, wt);
4198 st->print(" ");
4199 wt->print_on_error(st, buf, buflen);
4200 st->cr();
4201 }
4202 if (!found_current) {
4203 st->cr();
4204 st->print("=>" PTR_FORMAT " (exited) ", current);
4205 current->print_on_error(st, buf, buflen);
4206 st->cr();
4207 }
4208 }
4209
4210 // Internal SpinLock and Mutex
4211 // Based on ParkEvent
4212
4213 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4214 //
4215 // We employ SpinLocks _only for low-contention, fixed-length
4216 // short-duration critical sections where we're concerned
4217 // about native mutex_t or HotSpot Mutex:: latency.
4218 // The mux construct provides a spin-then-block mutual exclusion
4219 // mechanism.
4220 //
4221 // Testing has shown that contention on the ListLock guarding gFreeList
4222 // is common. If we implement ListLock as a simple SpinLock it's common
4223 // for the JVM to devolve to yielding with little progress. This is true
4224 // despite the fact that the critical sections protected by ListLock are
4225 // extremely short.
4226 //
4227 // TODO-FIXME: ListLock should be of type SpinLock.
4228 // We should make this a 1st-class type, integrated into the lock
4229 // hierarchy as leaf-locks. Critically, the SpinLock structure
4230 // should have sufficient padding to avoid false-sharing and excessive
4231 // cache-coherency traffic.
4232
4233
4234 typedef volatile int SpinLockT ;
4235
4236 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4237 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4238 return ; // normal fast-path return
4239 }
4240
4241 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4242 TEVENT (SpinAcquire - ctx) ;
4243 int ctr = 0 ;
4244 int Yields = 0 ;
4245 for (;;) {
4246 while (*adr != 0) {
4247 ++ctr ;
4248 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4249 if (Yields > 5) {
4250 // Consider using a simple NakedSleep() instead.
4251 // Then SpinAcquire could be called by non-JVM threads
4252 Thread::current()->_ParkEvent->park(1) ;
4253 } else {
4254 os::NakedYield() ;
4255 ++Yields ;
4256 }
4257 } else {
4258 SpinPause() ;
4259 }
4260 }
4261 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4262 }
4263 }
4264
4265 void Thread::SpinRelease (volatile int * adr) {
4266 assert (*adr != 0, "invariant") ;
4267 OrderAccess::fence() ; // guarantee at least release consistency.
4268 // Roach-motel semantics.
4269 // It's safe if subsequent LDs and STs float "up" into the critical section,
4270 // but prior LDs and STs within the critical section can't be allowed
4271 // to reorder or float past the ST that releases the lock.
4272 *adr = 0 ;
4273 }
4274
4275 // muxAcquire and muxRelease:
4276 //
4277 // * muxAcquire and muxRelease support a single-word lock-word construct.
4278 // The LSB of the word is set IFF the lock is held.
4279 // The remainder of the word points to the head of a singly-linked list
4280 // of threads blocked on the lock.
4281 //
4282 // * The current implementation of muxAcquire-muxRelease uses its own
4283 // dedicated Thread._MuxEvent instance. If we're interested in
4284 // minimizing the peak number of extant ParkEvent instances then
4285 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4286 // as certain invariants were satisfied. Specifically, care would need
4287 // to be taken with regards to consuming unpark() "permits".
4288 // A safe rule of thumb is that a thread would never call muxAcquire()
4289 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4290 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4291 // consume an unpark() permit intended for monitorenter, for instance.
4292 // One way around this would be to widen the restricted-range semaphore
4293 // implemented in park(). Another alternative would be to provide
4294 // multiple instances of the PlatformEvent() for each thread. One
4295 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4296 //
4297 // * Usage:
4298 // -- Only as leaf locks
4299 // -- for short-term locking only as muxAcquire does not perform
4300 // thread state transitions.
4301 //
4302 // Alternatives:
4303 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4304 // but with parking or spin-then-park instead of pure spinning.
4305 // * Use Taura-Oyama-Yonenzawa locks.
4306 // * It's possible to construct a 1-0 lock if we encode the lockword as
4307 // (List,LockByte). Acquire will CAS the full lockword while Release
4308 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4309 // acquiring threads use timers (ParkTimed) to detect and recover from
4310 // the stranding window. Thread/Node structures must be aligned on 256-byte
4311 // boundaries by using placement-new.
4312 // * Augment MCS with advisory back-link fields maintained with CAS().
4313 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4314 // The validity of the backlinks must be ratified before we trust the value.
4315 // If the backlinks are invalid the exiting thread must back-track through the
4316 // the forward links, which are always trustworthy.
4317 // * Add a successor indication. The LockWord is currently encoded as
4318 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4319 // to provide the usual futile-wakeup optimization.
4320 // See RTStt for details.
4321 // * Consider schedctl.sc_nopreempt to cover the critical section.
4322 //
4323
4324
4325 typedef volatile intptr_t MutexT ; // Mux Lock-word
4326 enum MuxBits { LOCKBIT = 1 } ;
4327
4328 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4329 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4330 if (w == 0) return ;
4331 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4332 return ;
4333 }
4334
4335 TEVENT (muxAcquire - Contention) ;
4336 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4337 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4338 for (;;) {
4339 int its = (os::is_MP() ? 100 : 0) + 1 ;
4340
4341 // Optional spin phase: spin-then-park strategy
4342 while (--its >= 0) {
4343 w = *Lock ;
4344 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4345 return ;
4346 }
4347 }
4348
4349 Self->reset() ;
4350 Self->OnList = intptr_t(Lock) ;
4351 // The following fence() isn't _strictly necessary as the subsequent
4352 // CAS() both serializes execution and ratifies the fetched *Lock value.
4353 OrderAccess::fence();
4354 for (;;) {
4355 w = *Lock ;
4356 if ((w & LOCKBIT) == 0) {
4357 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4358 Self->OnList = 0 ; // hygiene - allows stronger asserts
4359 return ;
4360 }
4361 continue ; // Interference -- *Lock changed -- Just retry
4362 }
4363 assert (w & LOCKBIT, "invariant") ;
4364 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4365 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4366 }
4367
4368 while (Self->OnList != 0) {
4369 Self->park() ;
4370 }
4371 }
4372 }
4373
4374 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4375 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4376 if (w == 0) return ;
4377 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4378 return ;
4379 }
4380
4381 TEVENT (muxAcquire - Contention) ;
4382 ParkEvent * ReleaseAfter = NULL ;
4383 if (ev == NULL) {
4384 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4385 }
4386 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4387 for (;;) {
4388 guarantee (ev->OnList == 0, "invariant") ;
4389 int its = (os::is_MP() ? 100 : 0) + 1 ;
4390
4391 // Optional spin phase: spin-then-park strategy
4392 while (--its >= 0) {
4393 w = *Lock ;
4394 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4395 if (ReleaseAfter != NULL) {
4396 ParkEvent::Release (ReleaseAfter) ;
4397 }
4398 return ;
4399 }
4400 }
4401
4402 ev->reset() ;
4403 ev->OnList = intptr_t(Lock) ;
4404 // The following fence() isn't _strictly necessary as the subsequent
4405 // CAS() both serializes execution and ratifies the fetched *Lock value.
4406 OrderAccess::fence();
4407 for (;;) {
4408 w = *Lock ;
4409 if ((w & LOCKBIT) == 0) {
4410 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4411 ev->OnList = 0 ;
4412 // We call ::Release while holding the outer lock, thus
4413 // artificially lengthening the critical section.
4414 // Consider deferring the ::Release() until the subsequent unlock(),
4415 // after we've dropped the outer lock.
4416 if (ReleaseAfter != NULL) {
4417 ParkEvent::Release (ReleaseAfter) ;
4418 }
4419 return ;
4420 }
4421 continue ; // Interference -- *Lock changed -- Just retry
4422 }
4423 assert (w & LOCKBIT, "invariant") ;
4424 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4425 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4426 }
4427
4428 while (ev->OnList != 0) {
4429 ev->park() ;
4430 }
4431 }
4432 }
4433
4434 // Release() must extract a successor from the list and then wake that thread.
4435 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4436 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4437 // Release() would :
4438 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4439 // (B) Extract a successor from the private list "in-hand"
4440 // (C) attempt to CAS() the residual back into *Lock over null.
4441 // If there were any newly arrived threads and the CAS() would fail.
4442 // In that case Release() would detach the RATs, re-merge the list in-hand
4443 // with the RATs and repeat as needed. Alternately, Release() might
4444 // detach and extract a successor, but then pass the residual list to the wakee.
4445 // The wakee would be responsible for reattaching and remerging before it
4446 // competed for the lock.
4447 //
4448 // Both "pop" and DMR are immune from ABA corruption -- there can be
4449 // multiple concurrent pushers, but only one popper or detacher.
4450 // This implementation pops from the head of the list. This is unfair,
4451 // but tends to provide excellent throughput as hot threads remain hot.
4452 // (We wake recently run threads first).
4453
4454 void Thread::muxRelease (volatile intptr_t * Lock) {
4455 for (;;) {
4456 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4457 assert (w & LOCKBIT, "invariant") ;
4458 if (w == LOCKBIT) return ;
4459 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4460 assert (List != NULL, "invariant") ;
4461 assert (List->OnList == intptr_t(Lock), "invariant") ;
4462 ParkEvent * nxt = List->ListNext ;
4463
4464 // The following CAS() releases the lock and pops the head element.
4465 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4466 continue ;
4467 }
4468 List->OnList = 0 ;
4469 OrderAccess::fence() ;
4470 List->unpark () ;
4471 return ;
4472 }
4473 }
4474
4475
4476 void Threads::verify() {
4477 ALL_JAVA_THREADS(p) {
4478 p->verify();
4479 }
4480 VMThread* thread = VMThread::vm_thread();
4481 if (thread != NULL) thread->verify();
4482 }