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 #ifdef ASSERT
251 _visited_for_critical_count = false;
252 #endif
253
254 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
255 _suspend_flags = 0;
256
257 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
258 _hashStateX = os::random() ;
259 _hashStateY = 842502087 ;
260 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
261 _hashStateW = 273326509 ;
262
263 _OnTrap = 0 ;
264 _schedctl = NULL ;
265 _Stalled = 0 ;
266 _TypeTag = 0x2BAD ;
267
268 // Many of the following fields are effectively final - immutable
269 // Note that nascent threads can't use the Native Monitor-Mutex
270 // construct until the _MutexEvent is initialized ...
271 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
272 // we might instead use a stack of ParkEvents that we could provision on-demand.
273 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
274 // and ::Release()
275 _ParkEvent = ParkEvent::Allocate (this) ;
276 _SleepEvent = ParkEvent::Allocate (this) ;
277 _MutexEvent = ParkEvent::Allocate (this) ;
278 _MuxEvent = ParkEvent::Allocate (this) ;
279
280 #ifdef CHECK_UNHANDLED_OOPS
281 if (CheckUnhandledOops) {
282 _unhandled_oops = new UnhandledOops(this);
283 }
284 #endif // CHECK_UNHANDLED_OOPS
285 #ifdef ASSERT
286 if (UseBiasedLocking) {
287 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
288 assert(this == _real_malloc_address ||
289 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
290 "bug in forced alignment of thread objects");
291 }
292 #endif /* ASSERT */
293 }
294
295 void Thread::initialize_thread_local_storage() {
296 // Note: Make sure this method only calls
297 // non-blocking operations. Otherwise, it might not work
298 // with the thread-startup/safepoint interaction.
299
300 // During Java thread startup, safepoint code should allow this
301 // method to complete because it may need to allocate memory to
302 // store information for the new thread.
303
304 // initialize structure dependent on thread local storage
305 ThreadLocalStorage::set_thread(this);
306
307 // set up any platform-specific state.
308 os::initialize_thread();
309
310 }
311
312 void Thread::record_stack_base_and_size() {
313 set_stack_base(os::current_stack_base());
314 set_stack_size(os::current_stack_size());
315 }
316
317
318 Thread::~Thread() {
319 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
320 ObjectSynchronizer::omFlush (this) ;
321
322 // deallocate data structures
323 delete resource_area();
324 // since the handle marks are using the handle area, we have to deallocated the root
325 // handle mark before deallocating the thread's handle area,
326 assert(last_handle_mark() != NULL, "check we have an element");
327 delete last_handle_mark();
328 assert(last_handle_mark() == NULL, "check we have reached the end");
329
330 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
331 // We NULL out the fields for good hygiene.
332 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
333 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
334 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
335 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
336
337 delete handle_area();
338
339 // osthread() can be NULL, if creation of thread failed.
340 if (osthread() != NULL) os::free_thread(osthread());
341
342 delete _SR_lock;
343
344 // clear thread local storage if the Thread is deleting itself
345 if (this == Thread::current()) {
346 ThreadLocalStorage::set_thread(NULL);
347 } else {
348 // In the case where we're not the current thread, invalidate all the
349 // caches in case some code tries to get the current thread or the
350 // thread that was destroyed, and gets stale information.
351 ThreadLocalStorage::invalidate_all();
352 }
353 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
354 }
355
356 // NOTE: dummy function for assertion purpose.
357 void Thread::run() {
358 ShouldNotReachHere();
359 }
360
361 #ifdef ASSERT
362 // Private method to check for dangling thread pointer
363 void check_for_dangling_thread_pointer(Thread *thread) {
364 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
365 "possibility of dangling Thread pointer");
366 }
367 #endif
368
369
370 #ifndef PRODUCT
371 // Tracing method for basic thread operations
372 void Thread::trace(const char* msg, const Thread* const thread) {
373 if (!TraceThreadEvents) return;
374 ResourceMark rm;
375 ThreadCritical tc;
376 const char *name = "non-Java thread";
377 int prio = -1;
378 if (thread->is_Java_thread()
379 && !thread->is_Compiler_thread()) {
380 // The Threads_lock must be held to get information about
381 // this thread but may not be in some situations when
382 // tracing thread events.
383 bool release_Threads_lock = false;
384 if (!Threads_lock->owned_by_self()) {
385 Threads_lock->lock();
386 release_Threads_lock = true;
387 }
388 JavaThread* jt = (JavaThread *)thread;
389 name = (char *)jt->get_thread_name();
390 oop thread_oop = jt->threadObj();
391 if (thread_oop != NULL) {
392 prio = java_lang_Thread::priority(thread_oop);
393 }
394 if (release_Threads_lock) {
395 Threads_lock->unlock();
396 }
397 }
398 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
399 }
400 #endif
401
402
403 ThreadPriority Thread::get_priority(const Thread* const thread) {
404 trace("get priority", thread);
405 ThreadPriority priority;
406 // Can return an error!
407 (void)os::get_priority(thread, priority);
408 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
409 return priority;
410 }
411
412 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
413 trace("set priority", thread);
414 debug_only(check_for_dangling_thread_pointer(thread);)
415 // Can return an error!
416 (void)os::set_priority(thread, priority);
417 }
418
419
420 void Thread::start(Thread* thread) {
421 trace("start", thread);
422 // Start is different from resume in that its safety is guaranteed by context or
423 // being called from a Java method synchronized on the Thread object.
424 if (!DisableStartThread) {
425 if (thread->is_Java_thread()) {
426 // Initialize the thread state to RUNNABLE before starting this thread.
427 // Can not set it after the thread started because we do not know the
428 // exact thread state at that time. It could be in MONITOR_WAIT or
429 // in SLEEPING or some other state.
430 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
431 java_lang_Thread::RUNNABLE);
432 }
433 os::start_thread(thread);
434 }
435 }
436
437 // Enqueue a VM_Operation to do the job for us - sometime later
438 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
439 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
440 VMThread::execute(vm_stop);
441 }
442
443
444 //
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469 //
470
471 // Helper class for tracing suspend wait debug bits.
472 //
473 // 0x00000100 indicates that the target thread exited before it could
474 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
475 // 0x00080000 each indicate a cancelled suspend request so they don't
476 // count as wait failures either.
477 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
478
479 class TraceSuspendDebugBits : public StackObj {
480 private:
481 JavaThread * jt;
482 bool is_wait;
483 bool called_by_wait; // meaningful when !is_wait
484 uint32_t * bits;
485
486 public:
487 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
488 uint32_t *_bits) {
489 jt = _jt;
490 is_wait = _is_wait;
491 called_by_wait = _called_by_wait;
492 bits = _bits;
493 }
494
495 ~TraceSuspendDebugBits() {
496 if (!is_wait) {
497 #if 1
498 // By default, don't trace bits for is_ext_suspend_completed() calls.
499 // That trace is very chatty.
500 return;
501 #else
502 if (!called_by_wait) {
503 // If tracing for is_ext_suspend_completed() is enabled, then only
504 // trace calls to it from wait_for_ext_suspend_completion()
505 return;
506 }
507 #endif
508 }
509
510 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
511 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
512 MutexLocker ml(Threads_lock); // needed for get_thread_name()
513 ResourceMark rm;
514
515 tty->print_cr(
516 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
517 jt->get_thread_name(), *bits);
518
519 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
520 }
521 }
522 }
523 };
524 #undef DEBUG_FALSE_BITS
525
526
527 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
529
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
532
533 *bits |= 0x00000001;
534
535 do {
536 do_trans_retry = false;
537
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
544
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
552
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
558
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
571
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
608
609 *bits |= 0x00004000;
610
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
616
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
625
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
630
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
639
640
641 }
642 } while (do_trans_retry);
643
644 *bits |= 0x00000010;
645 return false;
646 }
647
648 //
649 // Wait for an external suspend request to complete (or be cancelled).
650 // Returns true if the thread is externally suspended and false otherwise.
651 //
652 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
653 uint32_t *bits) {
654 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
655 false /* !called_by_wait */, bits);
656
657 // local flag copies to minimize SR_lock hold time
658 bool is_suspended;
659 bool pending;
660 uint32_t reset_bits;
661
662 // set a marker so is_ext_suspend_completed() knows we are the caller
663 *bits |= 0x00010000;
664
665 // We use reset_bits to reinitialize the bits value at the top of
666 // each retry loop. This allows the caller to make use of any
667 // unused bits for their own marking purposes.
668 reset_bits = *bits;
669
670 {
671 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
672 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
673 delay, bits);
674 pending = is_external_suspend();
675 }
676 // must release SR_lock to allow suspension to complete
677
678 if (!pending) {
679 // A cancelled suspend request is the only false return from
680 // is_ext_suspend_completed() that keeps us from entering the
681 // retry loop.
682 *bits |= 0x00020000;
683 return false;
684 }
685
686 if (is_suspended) {
687 *bits |= 0x00040000;
688 return true;
689 }
690
691 for (int i = 1; i <= retries; i++) {
692 *bits = reset_bits; // reinit to only track last retry
693
694 // We used to do an "os::yield_all(i)" call here with the intention
695 // that yielding would increase on each retry. However, the parameter
696 // is ignored on Linux which means the yield didn't scale up. Waiting
697 // on the SR_lock below provides a much more predictable scale up for
698 // the delay. It also provides a simple/direct point to check for any
699 // safepoint requests from the VMThread
700
701 {
702 MutexLocker ml(SR_lock());
703 // wait with safepoint check (if we're a JavaThread - the WatcherThread
704 // can also call this) and increase delay with each retry
705 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
706
707 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
708 delay, bits);
709
710 // It is possible for the external suspend request to be cancelled
711 // (by a resume) before the actual suspend operation is completed.
712 // Refresh our local copy to see if we still need to wait.
713 pending = is_external_suspend();
714 }
715
716 if (!pending) {
717 // A cancelled suspend request is the only false return from
718 // is_ext_suspend_completed() that keeps us from staying in the
719 // retry loop.
720 *bits |= 0x00080000;
721 return false;
722 }
723
724 if (is_suspended) {
725 *bits |= 0x00100000;
726 return true;
727 }
728 } // end retry loop
729
730 // thread did not suspend after all our retries
731 *bits |= 0x00200000;
732 return false;
733 }
734
735 #ifndef PRODUCT
736 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
737
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existant
740 // and we don't care that much anyway.
741
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif /* PRODUCT */
750
751 // Called by flat profiler
752 // Callers have already called wait_for_ext_suspend_completion
753 // The assertion for that is currently too complex to put here:
754 bool JavaThread::profile_last_Java_frame(frame* _fr) {
755 bool gotframe = false;
756 // self suspension saves needed state.
757 if (has_last_Java_frame() && _anchor.walkable()) {
758 *_fr = pd_last_frame();
759 gotframe = true;
760 }
761 return gotframe;
762 }
763
764 void Thread::interrupt(Thread* thread) {
765 trace("interrupt", thread);
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 os::interrupt(thread);
768 }
769
770 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
771 trace("is_interrupted", thread);
772 debug_only(check_for_dangling_thread_pointer(thread);)
773 // Note: If clear_interrupted==false, this simply fetches and
774 // returns the value of the field osthread()->interrupted().
775 return os::is_interrupted(thread, clear_interrupted);
776 }
777
778
779 // GC Support
780 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
781 jint thread_parity = _oops_do_parity;
782 if (thread_parity != strong_roots_parity) {
783 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
784 if (res == thread_parity) {
785 return true;
786 } else {
787 guarantee(res == strong_roots_parity, "Or else what?");
788 assert(SharedHeap::heap()->workers()->active_workers() > 0,
789 "Should only fail when parallel.");
790 return false;
791 }
792 }
793 assert(SharedHeap::heap()->workers()->active_workers() > 0,
794 "Should only fail when parallel.");
795 return false;
796 }
797
798 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
799 active_handles()->oops_do(f);
800 // Do oop for ThreadShadow
801 f->do_oop((oop*)&_pending_exception);
802 handle_area()->oops_do(f);
803 }
804
805 void Thread::nmethods_do(CodeBlobClosure* cf) {
806 // no nmethods in a generic thread...
807 }
808
809 void Thread::print_on(outputStream* st) const {
810 // get_priority assumes osthread initialized
811 if (osthread() != NULL) {
812 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
813 osthread()->print_on(st);
814 }
815 debug_only(if (WizardMode) print_owned_locks_on(st);)
816 }
817
818 // Thread::print_on_error() is called by fatal error handler. Don't use
819 // any lock or allocate memory.
820 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
821 if (is_VM_thread()) st->print("VMThread");
822 else if (is_Compiler_thread()) st->print("CompilerThread");
823 else if (is_Java_thread()) st->print("JavaThread");
824 else if (is_GC_task_thread()) st->print("GCTaskThread");
825 else if (is_Watcher_thread()) st->print("WatcherThread");
826 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
827 else st->print("Thread");
828
829 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
830 _stack_base - _stack_size, _stack_base);
831
832 if (osthread()) {
833 st->print(" [id=%d]", osthread()->thread_id());
834 }
835 }
836
837 #ifdef ASSERT
838 void Thread::print_owned_locks_on(outputStream* st) const {
839 Monitor *cur = _owned_locks;
840 if (cur == NULL) {
841 st->print(" (no locks) ");
842 } else {
843 st->print_cr(" Locks owned:");
844 while(cur) {
845 cur->print_on(st);
846 cur = cur->next();
847 }
848 }
849 }
850
851 static int ref_use_count = 0;
852
853 bool Thread::owns_locks_but_compiled_lock() const {
854 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
855 if (cur != Compile_lock) return true;
856 }
857 return false;
858 }
859
860
861 #endif
862
863 #ifndef PRODUCT
864
865 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
866 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
867 // no threads which allow_vm_block's are held
868 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
869 // Check if current thread is allowed to block at a safepoint
870 if (!(_allow_safepoint_count == 0))
871 fatal("Possible safepoint reached by thread that does not allow it");
872 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
873 fatal("LEAF method calling lock?");
874 }
875
876 #ifdef ASSERT
877 if (potential_vm_operation && is_Java_thread()
878 && !Universe::is_bootstrapping()) {
879 // Make sure we do not hold any locks that the VM thread also uses.
880 // This could potentially lead to deadlocks
881 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
882 // Threads_lock is special, since the safepoint synchronization will not start before this is
883 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
884 // since it is used to transfer control between JavaThreads and the VMThread
885 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
886 if ( (cur->allow_vm_block() &&
887 cur != Threads_lock &&
888 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
889 cur != VMOperationRequest_lock &&
890 cur != VMOperationQueue_lock) ||
891 cur->rank() == Mutex::special) {
892 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
893 }
894 }
895 }
896
897 if (GCALotAtAllSafepoints) {
898 // We could enter a safepoint here and thus have a gc
899 InterfaceSupport::check_gc_alot();
900 }
901 #endif
902 }
903 #endif
904
905 bool Thread::is_in_stack(address adr) const {
906 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
907 address end = os::current_stack_pointer();
908 if (stack_base() >= adr && adr >= end) return true;
909
910 return false;
911 }
912
913
914 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
915 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
916 // used for compilation in the future. If that change is made, the need for these methods
917 // should be revisited, and they should be removed if possible.
918
919 bool Thread::is_lock_owned(address adr) const {
920 return on_local_stack(adr);
921 }
922
923 bool Thread::set_as_starting_thread() {
924 // NOTE: this must be called inside the main thread.
925 return os::create_main_thread((JavaThread*)this);
926 }
927
928 static void initialize_class(Symbol* class_name, TRAPS) {
929 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
930 instanceKlass::cast(klass)->initialize(CHECK);
931 }
932
933
934 // Creates the initial ThreadGroup
935 static Handle create_initial_thread_group(TRAPS) {
936 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
937 instanceKlassHandle klass (THREAD, k);
938
939 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
940 {
941 JavaValue result(T_VOID);
942 JavaCalls::call_special(&result,
943 system_instance,
944 klass,
945 vmSymbols::object_initializer_name(),
946 vmSymbols::void_method_signature(),
947 CHECK_NH);
948 }
949 Universe::set_system_thread_group(system_instance());
950
951 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
952 {
953 JavaValue result(T_VOID);
954 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
955 JavaCalls::call_special(&result,
956 main_instance,
957 klass,
958 vmSymbols::object_initializer_name(),
959 vmSymbols::threadgroup_string_void_signature(),
960 system_instance,
961 string,
962 CHECK_NH);
963 }
964 return main_instance;
965 }
966
967 // Creates the initial Thread
968 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
969 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
970 instanceKlassHandle klass (THREAD, k);
971 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
972
973 java_lang_Thread::set_thread(thread_oop(), thread);
974 java_lang_Thread::set_priority(thread_oop(), NormPriority);
975 thread->set_threadObj(thread_oop());
976
977 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
978
979 JavaValue result(T_VOID);
980 JavaCalls::call_special(&result, thread_oop,
981 klass,
982 vmSymbols::object_initializer_name(),
983 vmSymbols::threadgroup_string_void_signature(),
984 thread_group,
985 string,
986 CHECK_NULL);
987 return thread_oop();
988 }
989
990 static void call_initializeSystemClass(TRAPS) {
991 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
992 instanceKlassHandle klass (THREAD, k);
993
994 JavaValue result(T_VOID);
995 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
996 vmSymbols::void_method_signature(), CHECK);
997 }
998
999 // General purpose hook into Java code, run once when the VM is initialized.
1000 // The Java library method itself may be changed independently from the VM.
1001 static void call_postVMInitHook(TRAPS) {
1002 klassOop k = SystemDictionary::PostVMInitHook_klass();
1003 instanceKlassHandle klass (THREAD, k);
1004 if (klass.not_null()) {
1005 JavaValue result(T_VOID);
1006 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1007 vmSymbols::void_method_signature(),
1008 CHECK);
1009 }
1010 }
1011
1012 static void reset_vm_info_property(TRAPS) {
1013 // the vm info string
1014 ResourceMark rm(THREAD);
1015 const char *vm_info = VM_Version::vm_info_string();
1016
1017 // java.lang.System class
1018 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1019 instanceKlassHandle klass (THREAD, k);
1020
1021 // setProperty arguments
1022 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1023 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1024
1025 // return value
1026 JavaValue r(T_OBJECT);
1027
1028 // public static String setProperty(String key, String value);
1029 JavaCalls::call_static(&r,
1030 klass,
1031 vmSymbols::setProperty_name(),
1032 vmSymbols::string_string_string_signature(),
1033 key_str,
1034 value_str,
1035 CHECK);
1036 }
1037
1038
1039 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1040 assert(thread_group.not_null(), "thread group should be specified");
1041 assert(threadObj() == NULL, "should only create Java thread object once");
1042
1043 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1044 instanceKlassHandle klass (THREAD, k);
1045 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1046
1047 java_lang_Thread::set_thread(thread_oop(), this);
1048 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1049 set_threadObj(thread_oop());
1050
1051 JavaValue result(T_VOID);
1052 if (thread_name != NULL) {
1053 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1054 // Thread gets assigned specified name and null target
1055 JavaCalls::call_special(&result,
1056 thread_oop,
1057 klass,
1058 vmSymbols::object_initializer_name(),
1059 vmSymbols::threadgroup_string_void_signature(),
1060 thread_group, // Argument 1
1061 name, // Argument 2
1062 THREAD);
1063 } else {
1064 // Thread gets assigned name "Thread-nnn" and null target
1065 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1066 JavaCalls::call_special(&result,
1067 thread_oop,
1068 klass,
1069 vmSymbols::object_initializer_name(),
1070 vmSymbols::threadgroup_runnable_void_signature(),
1071 thread_group, // Argument 1
1072 Handle(), // Argument 2
1073 THREAD);
1074 }
1075
1076
1077 if (daemon) {
1078 java_lang_Thread::set_daemon(thread_oop());
1079 }
1080
1081 if (HAS_PENDING_EXCEPTION) {
1082 return;
1083 }
1084
1085 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1086 Handle threadObj(this, this->threadObj());
1087
1088 JavaCalls::call_special(&result,
1089 thread_group,
1090 group,
1091 vmSymbols::add_method_name(),
1092 vmSymbols::thread_void_signature(),
1093 threadObj, // Arg 1
1094 THREAD);
1095
1096
1097 }
1098
1099 // NamedThread -- non-JavaThread subclasses with multiple
1100 // uniquely named instances should derive from this.
1101 NamedThread::NamedThread() : Thread() {
1102 _name = NULL;
1103 _processed_thread = NULL;
1104 }
1105
1106 NamedThread::~NamedThread() {
1107 if (_name != NULL) {
1108 FREE_C_HEAP_ARRAY(char, _name);
1109 _name = NULL;
1110 }
1111 }
1112
1113 void NamedThread::set_name(const char* format, ...) {
1114 guarantee(_name == NULL, "Only get to set name once.");
1115 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1116 guarantee(_name != NULL, "alloc failure");
1117 va_list ap;
1118 va_start(ap, format);
1119 jio_vsnprintf(_name, max_name_len, format, ap);
1120 va_end(ap);
1121 }
1122
1123 // ======= WatcherThread ========
1124
1125 // The watcher thread exists to simulate timer interrupts. It should
1126 // be replaced by an abstraction over whatever native support for
1127 // timer interrupts exists on the platform.
1128
1129 WatcherThread* WatcherThread::_watcher_thread = NULL;
1130 volatile bool WatcherThread::_should_terminate = false;
1131
1132 WatcherThread::WatcherThread() : Thread() {
1133 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1134 if (os::create_thread(this, os::watcher_thread)) {
1135 _watcher_thread = this;
1136
1137 // Set the watcher thread to the highest OS priority which should not be
1138 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1139 // is created. The only normal thread using this priority is the reference
1140 // handler thread, which runs for very short intervals only.
1141 // If the VMThread's priority is not lower than the WatcherThread profiling
1142 // will be inaccurate.
1143 os::set_priority(this, MaxPriority);
1144 if (!DisableStartThread) {
1145 os::start_thread(this);
1146 }
1147 }
1148 }
1149
1150 void WatcherThread::run() {
1151 assert(this == watcher_thread(), "just checking");
1152
1153 this->record_stack_base_and_size();
1154 this->initialize_thread_local_storage();
1155 this->set_active_handles(JNIHandleBlock::allocate_block());
1156 while(!_should_terminate) {
1157 assert(watcher_thread() == Thread::current(), "thread consistency check");
1158 assert(watcher_thread() == this, "thread consistency check");
1159
1160 // Calculate how long it'll be until the next PeriodicTask work
1161 // should be done, and sleep that amount of time.
1162 size_t time_to_wait = PeriodicTask::time_to_wait();
1163
1164 // we expect this to timeout - we only ever get unparked when
1165 // we should terminate
1166 {
1167 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1168
1169 jlong prev_time = os::javaTimeNanos();
1170 for (;;) {
1171 int res= _SleepEvent->park(time_to_wait);
1172 if (res == OS_TIMEOUT || _should_terminate)
1173 break;
1174 // spurious wakeup of some kind
1175 jlong now = os::javaTimeNanos();
1176 time_to_wait -= (now - prev_time) / 1000000;
1177 if (time_to_wait <= 0)
1178 break;
1179 prev_time = now;
1180 }
1181 }
1182
1183 if (is_error_reported()) {
1184 // A fatal error has happened, the error handler(VMError::report_and_die)
1185 // should abort JVM after creating an error log file. However in some
1186 // rare cases, the error handler itself might deadlock. Here we try to
1187 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1188 //
1189 // This code is in WatcherThread because WatcherThread wakes up
1190 // periodically so the fatal error handler doesn't need to do anything;
1191 // also because the WatcherThread is less likely to crash than other
1192 // threads.
1193
1194 for (;;) {
1195 if (!ShowMessageBoxOnError
1196 && (OnError == NULL || OnError[0] == '\0')
1197 && Arguments::abort_hook() == NULL) {
1198 os::sleep(this, 2 * 60 * 1000, false);
1199 fdStream err(defaultStream::output_fd());
1200 err.print_raw_cr("# [ timer expired, abort... ]");
1201 // skip atexit/vm_exit/vm_abort hooks
1202 os::die();
1203 }
1204
1205 // Wake up 5 seconds later, the fatal handler may reset OnError or
1206 // ShowMessageBoxOnError when it is ready to abort.
1207 os::sleep(this, 5 * 1000, false);
1208 }
1209 }
1210
1211 PeriodicTask::real_time_tick(time_to_wait);
1212
1213 // If we have no more tasks left due to dynamic disenrollment,
1214 // shut down the thread since we don't currently support dynamic enrollment
1215 if (PeriodicTask::num_tasks() == 0) {
1216 _should_terminate = true;
1217 }
1218 }
1219
1220 // Signal that it is terminated
1221 {
1222 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1223 _watcher_thread = NULL;
1224 Terminator_lock->notify();
1225 }
1226
1227 // Thread destructor usually does this..
1228 ThreadLocalStorage::set_thread(NULL);
1229 }
1230
1231 void WatcherThread::start() {
1232 if (watcher_thread() == NULL) {
1233 _should_terminate = false;
1234 // Create the single instance of WatcherThread
1235 new WatcherThread();
1236 }
1237 }
1238
1239 void WatcherThread::stop() {
1240 // it is ok to take late safepoints here, if needed
1241 MutexLocker mu(Terminator_lock);
1242 _should_terminate = true;
1243 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1244
1245 Thread* watcher = watcher_thread();
1246 if (watcher != NULL)
1247 watcher->_SleepEvent->unpark();
1248
1249 while(watcher_thread() != NULL) {
1250 // This wait should make safepoint checks, wait without a timeout,
1251 // and wait as a suspend-equivalent condition.
1252 //
1253 // Note: If the FlatProfiler is running, then this thread is waiting
1254 // for the WatcherThread to terminate and the WatcherThread, via the
1255 // FlatProfiler task, is waiting for the external suspend request on
1256 // this thread to complete. wait_for_ext_suspend_completion() will
1257 // eventually timeout, but that takes time. Making this wait a
1258 // suspend-equivalent condition solves that timeout problem.
1259 //
1260 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1261 Mutex::_as_suspend_equivalent_flag);
1262 }
1263 }
1264
1265 void WatcherThread::print_on(outputStream* st) const {
1266 st->print("\"%s\" ", name());
1267 Thread::print_on(st);
1268 st->cr();
1269 }
1270
1271 // ======= JavaThread ========
1272
1273 // A JavaThread is a normal Java thread
1274
1275 void JavaThread::initialize() {
1276 // Initialize fields
1277
1278 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1279 set_claimed_par_id(-1);
1280
1281 set_saved_exception_pc(NULL);
1282 set_threadObj(NULL);
1283 _anchor.clear();
1284 set_entry_point(NULL);
1285 set_jni_functions(jni_functions());
1286 set_callee_target(NULL);
1287 set_vm_result(NULL);
1288 set_vm_result_2(NULL);
1289 set_vframe_array_head(NULL);
1290 set_vframe_array_last(NULL);
1291 set_deferred_locals(NULL);
1292 set_deopt_mark(NULL);
1293 set_deopt_nmethod(NULL);
1294 clear_must_deopt_id();
1295 set_monitor_chunks(NULL);
1296 set_next(NULL);
1297 set_thread_state(_thread_new);
1298 _terminated = _not_terminated;
1299 _privileged_stack_top = NULL;
1300 _array_for_gc = NULL;
1301 _suspend_equivalent = false;
1302 _in_deopt_handler = 0;
1303 _doing_unsafe_access = false;
1304 _stack_guard_state = stack_guard_unused;
1305 _exception_oop = NULL;
1306 _exception_pc = 0;
1307 _exception_handler_pc = 0;
1308 _is_method_handle_return = 0;
1309 _jvmti_thread_state= NULL;
1310 _should_post_on_exceptions_flag = JNI_FALSE;
1311 _jvmti_get_loaded_classes_closure = NULL;
1312 _interp_only_mode = 0;
1313 _special_runtime_exit_condition = _no_async_condition;
1314 _pending_async_exception = NULL;
1315 _is_compiling = false;
1316 _thread_stat = NULL;
1317 _thread_stat = new ThreadStatistics();
1318 _blocked_on_compilation = false;
1319 _jni_active_critical = 0;
1320 _do_not_unlock_if_synchronized = false;
1321 _cached_monitor_info = NULL;
1322 _parker = Parker::Allocate(this) ;
1323
1324 #ifndef PRODUCT
1325 _jmp_ring_index = 0;
1326 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1327 record_jump(NULL, NULL, NULL, 0);
1328 }
1329 #endif /* PRODUCT */
1330
1331 set_thread_profiler(NULL);
1332 if (FlatProfiler::is_active()) {
1333 // This is where we would decide to either give each thread it's own profiler
1334 // or use one global one from FlatProfiler,
1335 // or up to some count of the number of profiled threads, etc.
1336 ThreadProfiler* pp = new ThreadProfiler();
1337 pp->engage();
1338 set_thread_profiler(pp);
1339 }
1340
1341 // Setup safepoint state info for this thread
1342 ThreadSafepointState::create(this);
1343
1344 debug_only(_java_call_counter = 0);
1345
1346 // JVMTI PopFrame support
1347 _popframe_condition = popframe_inactive;
1348 _popframe_preserved_args = NULL;
1349 _popframe_preserved_args_size = 0;
1350
1351 pd_initialize();
1352 }
1353
1354 #ifndef SERIALGC
1355 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1356 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1357 #endif // !SERIALGC
1358
1359 JavaThread::JavaThread(bool is_attaching_via_jni) :
1360 Thread()
1361 #ifndef SERIALGC
1362 , _satb_mark_queue(&_satb_mark_queue_set),
1363 _dirty_card_queue(&_dirty_card_queue_set)
1364 #endif // !SERIALGC
1365 {
1366 initialize();
1367 if (is_attaching_via_jni) {
1368 _jni_attach_state = _attaching_via_jni;
1369 } else {
1370 _jni_attach_state = _not_attaching_via_jni;
1371 }
1372 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1373 }
1374
1375 bool JavaThread::reguard_stack(address cur_sp) {
1376 if (_stack_guard_state != stack_guard_yellow_disabled) {
1377 return true; // Stack already guarded or guard pages not needed.
1378 }
1379
1380 if (register_stack_overflow()) {
1381 // For those architectures which have separate register and
1382 // memory stacks, we must check the register stack to see if
1383 // it has overflowed.
1384 return false;
1385 }
1386
1387 // Java code never executes within the yellow zone: the latter is only
1388 // there to provoke an exception during stack banging. If java code
1389 // is executing there, either StackShadowPages should be larger, or
1390 // some exception code in c1, c2 or the interpreter isn't unwinding
1391 // when it should.
1392 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1393
1394 enable_stack_yellow_zone();
1395 return true;
1396 }
1397
1398 bool JavaThread::reguard_stack(void) {
1399 return reguard_stack(os::current_stack_pointer());
1400 }
1401
1402
1403 void JavaThread::block_if_vm_exited() {
1404 if (_terminated == _vm_exited) {
1405 // _vm_exited is set at safepoint, and Threads_lock is never released
1406 // we will block here forever
1407 Threads_lock->lock_without_safepoint_check();
1408 ShouldNotReachHere();
1409 }
1410 }
1411
1412
1413 // Remove this ifdef when C1 is ported to the compiler interface.
1414 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1415
1416 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1417 Thread()
1418 #ifndef SERIALGC
1419 , _satb_mark_queue(&_satb_mark_queue_set),
1420 _dirty_card_queue(&_dirty_card_queue_set)
1421 #endif // !SERIALGC
1422 {
1423 if (TraceThreadEvents) {
1424 tty->print_cr("creating thread %p", this);
1425 }
1426 initialize();
1427 _jni_attach_state = _not_attaching_via_jni;
1428 set_entry_point(entry_point);
1429 // Create the native thread itself.
1430 // %note runtime_23
1431 os::ThreadType thr_type = os::java_thread;
1432 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1433 os::java_thread;
1434 os::create_thread(this, thr_type, stack_sz);
1435
1436 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1437 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1438 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1439 // the exception consists of creating the exception object & initializing it, initialization
1440 // will leave the VM via a JavaCall and then all locks must be unlocked).
1441 //
1442 // The thread is still suspended when we reach here. Thread must be explicit started
1443 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1444 // by calling Threads:add. The reason why this is not done here, is because the thread
1445 // object must be fully initialized (take a look at JVM_Start)
1446 }
1447
1448 JavaThread::~JavaThread() {
1449 if (TraceThreadEvents) {
1450 tty->print_cr("terminate thread %p", this);
1451 }
1452
1453 // JSR166 -- return the parker to the free list
1454 Parker::Release(_parker);
1455 _parker = NULL ;
1456
1457 // Free any remaining previous UnrollBlock
1458 vframeArray* old_array = vframe_array_last();
1459
1460 if (old_array != NULL) {
1461 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1462 old_array->set_unroll_block(NULL);
1463 delete old_info;
1464 delete old_array;
1465 }
1466
1467 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1468 if (deferred != NULL) {
1469 // This can only happen if thread is destroyed before deoptimization occurs.
1470 assert(deferred->length() != 0, "empty array!");
1471 do {
1472 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1473 deferred->remove_at(0);
1474 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1475 delete dlv;
1476 } while (deferred->length() != 0);
1477 delete deferred;
1478 }
1479
1480 // All Java related clean up happens in exit
1481 ThreadSafepointState::destroy(this);
1482 if (_thread_profiler != NULL) delete _thread_profiler;
1483 if (_thread_stat != NULL) delete _thread_stat;
1484 }
1485
1486
1487 // The first routine called by a new Java thread
1488 void JavaThread::run() {
1489 // initialize thread-local alloc buffer related fields
1490 this->initialize_tlab();
1491
1492 // used to test validitity of stack trace backs
1493 this->record_base_of_stack_pointer();
1494
1495 // Record real stack base and size.
1496 this->record_stack_base_and_size();
1497
1498 // Initialize thread local storage; set before calling MutexLocker
1499 this->initialize_thread_local_storage();
1500
1501 this->create_stack_guard_pages();
1502
1503 this->cache_global_variables();
1504
1505 // Thread is now sufficient initialized to be handled by the safepoint code as being
1506 // in the VM. Change thread state from _thread_new to _thread_in_vm
1507 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1508
1509 assert(JavaThread::current() == this, "sanity check");
1510 assert(!Thread::current()->owns_locks(), "sanity check");
1511
1512 DTRACE_THREAD_PROBE(start, this);
1513
1514 // This operation might block. We call that after all safepoint checks for a new thread has
1515 // been completed.
1516 this->set_active_handles(JNIHandleBlock::allocate_block());
1517
1518 if (JvmtiExport::should_post_thread_life()) {
1519 JvmtiExport::post_thread_start(this);
1520 }
1521
1522 EVENT_BEGIN(TraceEventThreadStart, event);
1523 EVENT_COMMIT(event,
1524 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1525
1526 // We call another function to do the rest so we are sure that the stack addresses used
1527 // from there will be lower than the stack base just computed
1528 thread_main_inner();
1529
1530 // Note, thread is no longer valid at this point!
1531 }
1532
1533
1534 void JavaThread::thread_main_inner() {
1535 assert(JavaThread::current() == this, "sanity check");
1536 assert(this->threadObj() != NULL, "just checking");
1537
1538 // Execute thread entry point unless this thread has a pending exception
1539 // or has been stopped before starting.
1540 // Note: Due to JVM_StopThread we can have pending exceptions already!
1541 if (!this->has_pending_exception() &&
1542 !java_lang_Thread::is_stillborn(this->threadObj())) {
1543 {
1544 ResourceMark rm(this);
1545 this->set_native_thread_name(this->get_thread_name());
1546 }
1547 HandleMark hm(this);
1548 this->entry_point()(this, this);
1549 }
1550
1551 DTRACE_THREAD_PROBE(stop, this);
1552
1553 this->exit(false);
1554 delete this;
1555 }
1556
1557
1558 static void ensure_join(JavaThread* thread) {
1559 // We do not need to grap the Threads_lock, since we are operating on ourself.
1560 Handle threadObj(thread, thread->threadObj());
1561 assert(threadObj.not_null(), "java thread object must exist");
1562 ObjectLocker lock(threadObj, thread);
1563 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1564 thread->clear_pending_exception();
1565 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1566 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1567 // Clear the native thread instance - this makes isAlive return false and allows the join()
1568 // to complete once we've done the notify_all below
1569 java_lang_Thread::set_thread(threadObj(), NULL);
1570 lock.notify_all(thread);
1571 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1572 thread->clear_pending_exception();
1573 }
1574
1575
1576 // For any new cleanup additions, please check to see if they need to be applied to
1577 // cleanup_failed_attach_current_thread as well.
1578 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1579 assert(this == JavaThread::current(), "thread consistency check");
1580 if (!InitializeJavaLangSystem) return;
1581
1582 HandleMark hm(this);
1583 Handle uncaught_exception(this, this->pending_exception());
1584 this->clear_pending_exception();
1585 Handle threadObj(this, this->threadObj());
1586 assert(threadObj.not_null(), "Java thread object should be created");
1587
1588 if (get_thread_profiler() != NULL) {
1589 get_thread_profiler()->disengage();
1590 ResourceMark rm;
1591 get_thread_profiler()->print(get_thread_name());
1592 }
1593
1594
1595 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1596 {
1597 EXCEPTION_MARK;
1598
1599 CLEAR_PENDING_EXCEPTION;
1600 }
1601 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1602 // has to be fixed by a runtime query method
1603 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1604 // JSR-166: change call from from ThreadGroup.uncaughtException to
1605 // java.lang.Thread.dispatchUncaughtException
1606 if (uncaught_exception.not_null()) {
1607 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1608 {
1609 EXCEPTION_MARK;
1610 // Check if the method Thread.dispatchUncaughtException() exists. If so
1611 // call it. Otherwise we have an older library without the JSR-166 changes,
1612 // so call ThreadGroup.uncaughtException()
1613 KlassHandle recvrKlass(THREAD, threadObj->klass());
1614 CallInfo callinfo;
1615 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1616 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1617 vmSymbols::dispatchUncaughtException_name(),
1618 vmSymbols::throwable_void_signature(),
1619 KlassHandle(), false, false, THREAD);
1620 CLEAR_PENDING_EXCEPTION;
1621 methodHandle method = callinfo.selected_method();
1622 if (method.not_null()) {
1623 JavaValue result(T_VOID);
1624 JavaCalls::call_virtual(&result,
1625 threadObj, thread_klass,
1626 vmSymbols::dispatchUncaughtException_name(),
1627 vmSymbols::throwable_void_signature(),
1628 uncaught_exception,
1629 THREAD);
1630 } else {
1631 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1632 JavaValue result(T_VOID);
1633 JavaCalls::call_virtual(&result,
1634 group, thread_group,
1635 vmSymbols::uncaughtException_name(),
1636 vmSymbols::thread_throwable_void_signature(),
1637 threadObj, // Arg 1
1638 uncaught_exception, // Arg 2
1639 THREAD);
1640 }
1641 if (HAS_PENDING_EXCEPTION) {
1642 ResourceMark rm(this);
1643 jio_fprintf(defaultStream::error_stream(),
1644 "\nException: %s thrown from the UncaughtExceptionHandler"
1645 " in thread \"%s\"\n",
1646 Klass::cast(pending_exception()->klass())->external_name(),
1647 get_thread_name());
1648 CLEAR_PENDING_EXCEPTION;
1649 }
1650 }
1651 }
1652
1653 // Called before the java thread exit since we want to read info
1654 // from java_lang_Thread object
1655 EVENT_BEGIN(TraceEventThreadEnd, event);
1656 EVENT_COMMIT(event,
1657 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1658
1659 // Call after last event on thread
1660 EVENT_THREAD_EXIT(this);
1661
1662 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1663 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1664 // is deprecated anyhow.
1665 { int count = 3;
1666 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1667 EXCEPTION_MARK;
1668 JavaValue result(T_VOID);
1669 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1670 JavaCalls::call_virtual(&result,
1671 threadObj, thread_klass,
1672 vmSymbols::exit_method_name(),
1673 vmSymbols::void_method_signature(),
1674 THREAD);
1675 CLEAR_PENDING_EXCEPTION;
1676 }
1677 }
1678
1679 // notify JVMTI
1680 if (JvmtiExport::should_post_thread_life()) {
1681 JvmtiExport::post_thread_end(this);
1682 }
1683
1684 // We have notified the agents that we are exiting, before we go on,
1685 // we must check for a pending external suspend request and honor it
1686 // in order to not surprise the thread that made the suspend request.
1687 while (true) {
1688 {
1689 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1690 if (!is_external_suspend()) {
1691 set_terminated(_thread_exiting);
1692 ThreadService::current_thread_exiting(this);
1693 break;
1694 }
1695 // Implied else:
1696 // Things get a little tricky here. We have a pending external
1697 // suspend request, but we are holding the SR_lock so we
1698 // can't just self-suspend. So we temporarily drop the lock
1699 // and then self-suspend.
1700 }
1701
1702 ThreadBlockInVM tbivm(this);
1703 java_suspend_self();
1704
1705 // We're done with this suspend request, but we have to loop around
1706 // and check again. Eventually we will get SR_lock without a pending
1707 // external suspend request and will be able to mark ourselves as
1708 // exiting.
1709 }
1710 // no more external suspends are allowed at this point
1711 } else {
1712 // before_exit() has already posted JVMTI THREAD_END events
1713 }
1714
1715 // Notify waiters on thread object. This has to be done after exit() is called
1716 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1717 // group should have the destroyed bit set before waiters are notified).
1718 ensure_join(this);
1719 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1720
1721 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1722 // held by this thread must be released. A detach operation must only
1723 // get here if there are no Java frames on the stack. Therefore, any
1724 // owned monitors at this point MUST be JNI-acquired monitors which are
1725 // pre-inflated and in the monitor cache.
1726 //
1727 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1728 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1729 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1730 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1731 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1732 }
1733
1734 // These things needs to be done while we are still a Java Thread. Make sure that thread
1735 // is in a consistent state, in case GC happens
1736 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1737
1738 if (active_handles() != NULL) {
1739 JNIHandleBlock* block = active_handles();
1740 set_active_handles(NULL);
1741 JNIHandleBlock::release_block(block);
1742 }
1743
1744 if (free_handle_block() != NULL) {
1745 JNIHandleBlock* block = free_handle_block();
1746 set_free_handle_block(NULL);
1747 JNIHandleBlock::release_block(block);
1748 }
1749
1750 // These have to be removed while this is still a valid thread.
1751 remove_stack_guard_pages();
1752
1753 if (UseTLAB) {
1754 tlab().make_parsable(true); // retire TLAB
1755 }
1756
1757 if (JvmtiEnv::environments_might_exist()) {
1758 JvmtiExport::cleanup_thread(this);
1759 }
1760
1761 #ifndef SERIALGC
1762 // We must flush G1-related buffers before removing a thread from
1763 // the list of active threads.
1764 if (UseG1GC) {
1765 flush_barrier_queues();
1766 }
1767 #endif
1768
1769 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1770 Threads::remove(this);
1771 }
1772
1773 #ifndef SERIALGC
1774 // Flush G1-related queues.
1775 void JavaThread::flush_barrier_queues() {
1776 satb_mark_queue().flush();
1777 dirty_card_queue().flush();
1778 }
1779
1780 void JavaThread::initialize_queues() {
1781 assert(!SafepointSynchronize::is_at_safepoint(),
1782 "we should not be at a safepoint");
1783
1784 ObjPtrQueue& satb_queue = satb_mark_queue();
1785 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1786 // The SATB queue should have been constructed with its active
1787 // field set to false.
1788 assert(!satb_queue.is_active(), "SATB queue should not be active");
1789 assert(satb_queue.is_empty(), "SATB queue should be empty");
1790 // If we are creating the thread during a marking cycle, we should
1791 // set the active field of the SATB queue to true.
1792 if (satb_queue_set.is_active()) {
1793 satb_queue.set_active(true);
1794 }
1795
1796 DirtyCardQueue& dirty_queue = dirty_card_queue();
1797 // The dirty card queue should have been constructed with its
1798 // active field set to true.
1799 assert(dirty_queue.is_active(), "dirty card queue should be active");
1800 }
1801 #endif // !SERIALGC
1802
1803 void JavaThread::cleanup_failed_attach_current_thread() {
1804 if (get_thread_profiler() != NULL) {
1805 get_thread_profiler()->disengage();
1806 ResourceMark rm;
1807 get_thread_profiler()->print(get_thread_name());
1808 }
1809
1810 if (active_handles() != NULL) {
1811 JNIHandleBlock* block = active_handles();
1812 set_active_handles(NULL);
1813 JNIHandleBlock::release_block(block);
1814 }
1815
1816 if (free_handle_block() != NULL) {
1817 JNIHandleBlock* block = free_handle_block();
1818 set_free_handle_block(NULL);
1819 JNIHandleBlock::release_block(block);
1820 }
1821
1822 // These have to be removed while this is still a valid thread.
1823 remove_stack_guard_pages();
1824
1825 if (UseTLAB) {
1826 tlab().make_parsable(true); // retire TLAB, if any
1827 }
1828
1829 #ifndef SERIALGC
1830 if (UseG1GC) {
1831 flush_barrier_queues();
1832 }
1833 #endif
1834
1835 Threads::remove(this);
1836 delete this;
1837 }
1838
1839
1840
1841
1842 JavaThread* JavaThread::active() {
1843 Thread* thread = ThreadLocalStorage::thread();
1844 assert(thread != NULL, "just checking");
1845 if (thread->is_Java_thread()) {
1846 return (JavaThread*) thread;
1847 } else {
1848 assert(thread->is_VM_thread(), "this must be a vm thread");
1849 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1850 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1851 assert(ret->is_Java_thread(), "must be a Java thread");
1852 return ret;
1853 }
1854 }
1855
1856 bool JavaThread::is_lock_owned(address adr) const {
1857 if (Thread::is_lock_owned(adr)) return true;
1858
1859 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1860 if (chunk->contains(adr)) return true;
1861 }
1862
1863 return false;
1864 }
1865
1866
1867 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1868 chunk->set_next(monitor_chunks());
1869 set_monitor_chunks(chunk);
1870 }
1871
1872 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1873 guarantee(monitor_chunks() != NULL, "must be non empty");
1874 if (monitor_chunks() == chunk) {
1875 set_monitor_chunks(chunk->next());
1876 } else {
1877 MonitorChunk* prev = monitor_chunks();
1878 while (prev->next() != chunk) prev = prev->next();
1879 prev->set_next(chunk->next());
1880 }
1881 }
1882
1883 // JVM support.
1884
1885 // Note: this function shouldn't block if it's called in
1886 // _thread_in_native_trans state (such as from
1887 // check_special_condition_for_native_trans()).
1888 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1889
1890 if (has_last_Java_frame() && has_async_condition()) {
1891 // If we are at a polling page safepoint (not a poll return)
1892 // then we must defer async exception because live registers
1893 // will be clobbered by the exception path. Poll return is
1894 // ok because the call we a returning from already collides
1895 // with exception handling registers and so there is no issue.
1896 // (The exception handling path kills call result registers but
1897 // this is ok since the exception kills the result anyway).
1898
1899 if (is_at_poll_safepoint()) {
1900 // if the code we are returning to has deoptimized we must defer
1901 // the exception otherwise live registers get clobbered on the
1902 // exception path before deoptimization is able to retrieve them.
1903 //
1904 RegisterMap map(this, false);
1905 frame caller_fr = last_frame().sender(&map);
1906 assert(caller_fr.is_compiled_frame(), "what?");
1907 if (caller_fr.is_deoptimized_frame()) {
1908 if (TraceExceptions) {
1909 ResourceMark rm;
1910 tty->print_cr("deferred async exception at compiled safepoint");
1911 }
1912 return;
1913 }
1914 }
1915 }
1916
1917 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1918 if (condition == _no_async_condition) {
1919 // Conditions have changed since has_special_runtime_exit_condition()
1920 // was called:
1921 // - if we were here only because of an external suspend request,
1922 // then that was taken care of above (or cancelled) so we are done
1923 // - if we were here because of another async request, then it has
1924 // been cleared between the has_special_runtime_exit_condition()
1925 // and now so again we are done
1926 return;
1927 }
1928
1929 // Check for pending async. exception
1930 if (_pending_async_exception != NULL) {
1931 // Only overwrite an already pending exception, if it is not a threadDeath.
1932 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1933
1934 // We cannot call Exceptions::_throw(...) here because we cannot block
1935 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1936
1937 if (TraceExceptions) {
1938 ResourceMark rm;
1939 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1940 if (has_last_Java_frame() ) {
1941 frame f = last_frame();
1942 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1943 }
1944 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1945 }
1946 _pending_async_exception = NULL;
1947 clear_has_async_exception();
1948 }
1949 }
1950
1951 if (check_unsafe_error &&
1952 condition == _async_unsafe_access_error && !has_pending_exception()) {
1953 condition = _no_async_condition; // done
1954 switch (thread_state()) {
1955 case _thread_in_vm:
1956 {
1957 JavaThread* THREAD = this;
1958 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1959 }
1960 case _thread_in_native:
1961 {
1962 ThreadInVMfromNative tiv(this);
1963 JavaThread* THREAD = this;
1964 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1965 }
1966 case _thread_in_Java:
1967 {
1968 ThreadInVMfromJava tiv(this);
1969 JavaThread* THREAD = this;
1970 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1971 }
1972 default:
1973 ShouldNotReachHere();
1974 }
1975 }
1976
1977 assert(condition == _no_async_condition || has_pending_exception() ||
1978 (!check_unsafe_error && condition == _async_unsafe_access_error),
1979 "must have handled the async condition, if no exception");
1980 }
1981
1982 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1983 //
1984 // Check for pending external suspend. Internal suspend requests do
1985 // not use handle_special_runtime_exit_condition().
1986 // If JNIEnv proxies are allowed, don't self-suspend if the target
1987 // thread is not the current thread. In older versions of jdbx, jdbx
1988 // threads could call into the VM with another thread's JNIEnv so we
1989 // can be here operating on behalf of a suspended thread (4432884).
1990 bool do_self_suspend = is_external_suspend_with_lock();
1991 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1992 //
1993 // Because thread is external suspended the safepoint code will count
1994 // thread as at a safepoint. This can be odd because we can be here
1995 // as _thread_in_Java which would normally transition to _thread_blocked
1996 // at a safepoint. We would like to mark the thread as _thread_blocked
1997 // before calling java_suspend_self like all other callers of it but
1998 // we must then observe proper safepoint protocol. (We can't leave
1999 // _thread_blocked with a safepoint in progress). However we can be
2000 // here as _thread_in_native_trans so we can't use a normal transition
2001 // constructor/destructor pair because they assert on that type of
2002 // transition. We could do something like:
2003 //
2004 // JavaThreadState state = thread_state();
2005 // set_thread_state(_thread_in_vm);
2006 // {
2007 // ThreadBlockInVM tbivm(this);
2008 // java_suspend_self()
2009 // }
2010 // set_thread_state(_thread_in_vm_trans);
2011 // if (safepoint) block;
2012 // set_thread_state(state);
2013 //
2014 // but that is pretty messy. Instead we just go with the way the
2015 // code has worked before and note that this is the only path to
2016 // java_suspend_self that doesn't put the thread in _thread_blocked
2017 // mode.
2018
2019 frame_anchor()->make_walkable(this);
2020 java_suspend_self();
2021
2022 // We might be here for reasons in addition to the self-suspend request
2023 // so check for other async requests.
2024 }
2025
2026 if (check_asyncs) {
2027 check_and_handle_async_exceptions();
2028 }
2029 }
2030
2031 void JavaThread::send_thread_stop(oop java_throwable) {
2032 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2033 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2034 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2035
2036 // Do not throw asynchronous exceptions against the compiler thread
2037 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2038 if (is_Compiler_thread()) return;
2039
2040 {
2041 // Actually throw the Throwable against the target Thread - however
2042 // only if there is no thread death exception installed already.
2043 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2044 // If the topmost frame is a runtime stub, then we are calling into
2045 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2046 // must deoptimize the caller before continuing, as the compiled exception handler table
2047 // may not be valid
2048 if (has_last_Java_frame()) {
2049 frame f = last_frame();
2050 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2051 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2052 RegisterMap reg_map(this, UseBiasedLocking);
2053 frame compiled_frame = f.sender(®_map);
2054 if (compiled_frame.can_be_deoptimized()) {
2055 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2056 }
2057 }
2058 }
2059
2060 // Set async. pending exception in thread.
2061 set_pending_async_exception(java_throwable);
2062
2063 if (TraceExceptions) {
2064 ResourceMark rm;
2065 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2066 }
2067 // for AbortVMOnException flag
2068 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2069 }
2070 }
2071
2072
2073 // Interrupt thread so it will wake up from a potential wait()
2074 Thread::interrupt(this);
2075 }
2076
2077 // External suspension mechanism.
2078 //
2079 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2080 // to any VM_locks and it is at a transition
2081 // Self-suspension will happen on the transition out of the vm.
2082 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2083 //
2084 // Guarantees on return:
2085 // + Target thread will not execute any new bytecode (that's why we need to
2086 // force a safepoint)
2087 // + Target thread will not enter any new monitors
2088 //
2089 void JavaThread::java_suspend() {
2090 { MutexLocker mu(Threads_lock);
2091 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2092 return;
2093 }
2094 }
2095
2096 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2097 if (!is_external_suspend()) {
2098 // a racing resume has cancelled us; bail out now
2099 return;
2100 }
2101
2102 // suspend is done
2103 uint32_t debug_bits = 0;
2104 // Warning: is_ext_suspend_completed() may temporarily drop the
2105 // SR_lock to allow the thread to reach a stable thread state if
2106 // it is currently in a transient thread state.
2107 if (is_ext_suspend_completed(false /* !called_by_wait */,
2108 SuspendRetryDelay, &debug_bits) ) {
2109 return;
2110 }
2111 }
2112
2113 VM_ForceSafepoint vm_suspend;
2114 VMThread::execute(&vm_suspend);
2115 }
2116
2117 // Part II of external suspension.
2118 // A JavaThread self suspends when it detects a pending external suspend
2119 // request. This is usually on transitions. It is also done in places
2120 // where continuing to the next transition would surprise the caller,
2121 // e.g., monitor entry.
2122 //
2123 // Returns the number of times that the thread self-suspended.
2124 //
2125 // Note: DO NOT call java_suspend_self() when you just want to block current
2126 // thread. java_suspend_self() is the second stage of cooperative
2127 // suspension for external suspend requests and should only be used
2128 // to complete an external suspend request.
2129 //
2130 int JavaThread::java_suspend_self() {
2131 int ret = 0;
2132
2133 // we are in the process of exiting so don't suspend
2134 if (is_exiting()) {
2135 clear_external_suspend();
2136 return ret;
2137 }
2138
2139 assert(_anchor.walkable() ||
2140 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2141 "must have walkable stack");
2142
2143 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2144
2145 assert(!this->is_ext_suspended(),
2146 "a thread trying to self-suspend should not already be suspended");
2147
2148 if (this->is_suspend_equivalent()) {
2149 // If we are self-suspending as a result of the lifting of a
2150 // suspend equivalent condition, then the suspend_equivalent
2151 // flag is not cleared until we set the ext_suspended flag so
2152 // that wait_for_ext_suspend_completion() returns consistent
2153 // results.
2154 this->clear_suspend_equivalent();
2155 }
2156
2157 // A racing resume may have cancelled us before we grabbed SR_lock
2158 // above. Or another external suspend request could be waiting for us
2159 // by the time we return from SR_lock()->wait(). The thread
2160 // that requested the suspension may already be trying to walk our
2161 // stack and if we return now, we can change the stack out from under
2162 // it. This would be a "bad thing (TM)" and cause the stack walker
2163 // to crash. We stay self-suspended until there are no more pending
2164 // external suspend requests.
2165 while (is_external_suspend()) {
2166 ret++;
2167 this->set_ext_suspended();
2168
2169 // _ext_suspended flag is cleared by java_resume()
2170 while (is_ext_suspended()) {
2171 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2172 }
2173 }
2174
2175 return ret;
2176 }
2177
2178 #ifdef ASSERT
2179 // verify the JavaThread has not yet been published in the Threads::list, and
2180 // hence doesn't need protection from concurrent access at this stage
2181 void JavaThread::verify_not_published() {
2182 if (!Threads_lock->owned_by_self()) {
2183 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2184 assert( !Threads::includes(this),
2185 "java thread shouldn't have been published yet!");
2186 }
2187 else {
2188 assert( !Threads::includes(this),
2189 "java thread shouldn't have been published yet!");
2190 }
2191 }
2192 #endif
2193
2194 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2195 // progress or when _suspend_flags is non-zero.
2196 // Current thread needs to self-suspend if there is a suspend request and/or
2197 // block if a safepoint is in progress.
2198 // Async exception ISN'T checked.
2199 // Note only the ThreadInVMfromNative transition can call this function
2200 // directly and when thread state is _thread_in_native_trans
2201 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2202 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2203
2204 JavaThread *curJT = JavaThread::current();
2205 bool do_self_suspend = thread->is_external_suspend();
2206
2207 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2208
2209 // If JNIEnv proxies are allowed, don't self-suspend if the target
2210 // thread is not the current thread. In older versions of jdbx, jdbx
2211 // threads could call into the VM with another thread's JNIEnv so we
2212 // can be here operating on behalf of a suspended thread (4432884).
2213 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2214 JavaThreadState state = thread->thread_state();
2215
2216 // We mark this thread_blocked state as a suspend-equivalent so
2217 // that a caller to is_ext_suspend_completed() won't be confused.
2218 // The suspend-equivalent state is cleared by java_suspend_self().
2219 thread->set_suspend_equivalent();
2220
2221 // If the safepoint code sees the _thread_in_native_trans state, it will
2222 // wait until the thread changes to other thread state. There is no
2223 // guarantee on how soon we can obtain the SR_lock and complete the
2224 // self-suspend request. It would be a bad idea to let safepoint wait for
2225 // too long. Temporarily change the state to _thread_blocked to
2226 // let the VM thread know that this thread is ready for GC. The problem
2227 // of changing thread state is that safepoint could happen just after
2228 // java_suspend_self() returns after being resumed, and VM thread will
2229 // see the _thread_blocked state. We must check for safepoint
2230 // after restoring the state and make sure we won't leave while a safepoint
2231 // is in progress.
2232 thread->set_thread_state(_thread_blocked);
2233 thread->java_suspend_self();
2234 thread->set_thread_state(state);
2235 // Make sure new state is seen by VM thread
2236 if (os::is_MP()) {
2237 if (UseMembar) {
2238 // Force a fence between the write above and read below
2239 OrderAccess::fence();
2240 } else {
2241 // Must use this rather than serialization page in particular on Windows
2242 InterfaceSupport::serialize_memory(thread);
2243 }
2244 }
2245 }
2246
2247 if (SafepointSynchronize::do_call_back()) {
2248 // If we are safepointing, then block the caller which may not be
2249 // the same as the target thread (see above).
2250 SafepointSynchronize::block(curJT);
2251 }
2252
2253 if (thread->is_deopt_suspend()) {
2254 thread->clear_deopt_suspend();
2255 RegisterMap map(thread, false);
2256 frame f = thread->last_frame();
2257 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2258 f = f.sender(&map);
2259 }
2260 if (f.id() == thread->must_deopt_id()) {
2261 thread->clear_must_deopt_id();
2262 f.deoptimize(thread);
2263 } else {
2264 fatal("missed deoptimization!");
2265 }
2266 }
2267 }
2268
2269 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2270 // progress or when _suspend_flags is non-zero.
2271 // Current thread needs to self-suspend if there is a suspend request and/or
2272 // block if a safepoint is in progress.
2273 // Also check for pending async exception (not including unsafe access error).
2274 // Note only the native==>VM/Java barriers can call this function and when
2275 // thread state is _thread_in_native_trans.
2276 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2277 check_safepoint_and_suspend_for_native_trans(thread);
2278
2279 if (thread->has_async_exception()) {
2280 // We are in _thread_in_native_trans state, don't handle unsafe
2281 // access error since that may block.
2282 thread->check_and_handle_async_exceptions(false);
2283 }
2284 }
2285
2286 // This is a variant of the normal
2287 // check_special_condition_for_native_trans with slightly different
2288 // semantics for use by critical native wrappers. It does all the
2289 // normal checks but also performs the transition back into
2290 // thread_in_Java state. This is required so that critical natives
2291 // can potentially block and perform a GC if they are the last thread
2292 // exiting the GC_locker.
2293 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2294 check_special_condition_for_native_trans(thread);
2295
2296 // Finish the transition
2297 thread->set_thread_state(_thread_in_Java);
2298
2299 if (thread->do_critical_native_unlock()) {
2300 ThreadInVMfromJavaNoAsyncException tiv(thread);
2301 GC_locker::unlock_critical(thread);
2302 thread->clear_critical_native_unlock();
2303 }
2304 }
2305
2306 // We need to guarantee the Threads_lock here, since resumes are not
2307 // allowed during safepoint synchronization
2308 // Can only resume from an external suspension
2309 void JavaThread::java_resume() {
2310 assert_locked_or_safepoint(Threads_lock);
2311
2312 // Sanity check: thread is gone, has started exiting or the thread
2313 // was not externally suspended.
2314 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2315 return;
2316 }
2317
2318 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2319
2320 clear_external_suspend();
2321
2322 if (is_ext_suspended()) {
2323 clear_ext_suspended();
2324 SR_lock()->notify_all();
2325 }
2326 }
2327
2328 void JavaThread::create_stack_guard_pages() {
2329 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2330 address low_addr = stack_base() - stack_size();
2331 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2332
2333 int allocate = os::allocate_stack_guard_pages();
2334 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2335
2336 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2337 warning("Attempt to allocate stack guard pages failed.");
2338 return;
2339 }
2340
2341 if (os::guard_memory((char *) low_addr, len)) {
2342 _stack_guard_state = stack_guard_enabled;
2343 } else {
2344 warning("Attempt to protect stack guard pages failed.");
2345 if (os::uncommit_memory((char *) low_addr, len)) {
2346 warning("Attempt to deallocate stack guard pages failed.");
2347 }
2348 }
2349 }
2350
2351 void JavaThread::remove_stack_guard_pages() {
2352 if (_stack_guard_state == stack_guard_unused) return;
2353 address low_addr = stack_base() - stack_size();
2354 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2355
2356 if (os::allocate_stack_guard_pages()) {
2357 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2358 _stack_guard_state = stack_guard_unused;
2359 } else {
2360 warning("Attempt to deallocate stack guard pages failed.");
2361 }
2362 } else {
2363 if (_stack_guard_state == stack_guard_unused) return;
2364 if (os::unguard_memory((char *) low_addr, len)) {
2365 _stack_guard_state = stack_guard_unused;
2366 } else {
2367 warning("Attempt to unprotect stack guard pages failed.");
2368 }
2369 }
2370 }
2371
2372 void JavaThread::enable_stack_yellow_zone() {
2373 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2374 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2375
2376 // The base notation is from the stacks point of view, growing downward.
2377 // We need to adjust it to work correctly with guard_memory()
2378 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2379
2380 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2381 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2382
2383 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2384 _stack_guard_state = stack_guard_enabled;
2385 } else {
2386 warning("Attempt to guard stack yellow zone failed.");
2387 }
2388 enable_register_stack_guard();
2389 }
2390
2391 void JavaThread::disable_stack_yellow_zone() {
2392 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2393 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2394
2395 // Simply return if called for a thread that does not use guard pages.
2396 if (_stack_guard_state == stack_guard_unused) return;
2397
2398 // The base notation is from the stacks point of view, growing downward.
2399 // We need to adjust it to work correctly with guard_memory()
2400 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2401
2402 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2403 _stack_guard_state = stack_guard_yellow_disabled;
2404 } else {
2405 warning("Attempt to unguard stack yellow zone failed.");
2406 }
2407 disable_register_stack_guard();
2408 }
2409
2410 void JavaThread::enable_stack_red_zone() {
2411 // The base notation is from the stacks point of view, growing downward.
2412 // We need to adjust it to work correctly with guard_memory()
2413 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2414 address base = stack_red_zone_base() - stack_red_zone_size();
2415
2416 guarantee(base < stack_base(),"Error calculating stack red zone");
2417 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2418
2419 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2420 warning("Attempt to guard stack red zone failed.");
2421 }
2422 }
2423
2424 void JavaThread::disable_stack_red_zone() {
2425 // The base notation is from the stacks point of view, growing downward.
2426 // We need to adjust it to work correctly with guard_memory()
2427 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2428 address base = stack_red_zone_base() - stack_red_zone_size();
2429 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2430 warning("Attempt to unguard stack red zone failed.");
2431 }
2432 }
2433
2434 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2435 // ignore is there is no stack
2436 if (!has_last_Java_frame()) return;
2437 // traverse the stack frames. Starts from top frame.
2438 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2439 frame* fr = fst.current();
2440 f(fr, fst.register_map());
2441 }
2442 }
2443
2444
2445 #ifndef PRODUCT
2446 // Deoptimization
2447 // Function for testing deoptimization
2448 void JavaThread::deoptimize() {
2449 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2450 StackFrameStream fst(this, UseBiasedLocking);
2451 bool deopt = false; // Dump stack only if a deopt actually happens.
2452 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2453 // Iterate over all frames in the thread and deoptimize
2454 for(; !fst.is_done(); fst.next()) {
2455 if(fst.current()->can_be_deoptimized()) {
2456
2457 if (only_at) {
2458 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2459 // consists of comma or carriage return separated numbers so
2460 // search for the current bci in that string.
2461 address pc = fst.current()->pc();
2462 nmethod* nm = (nmethod*) fst.current()->cb();
2463 ScopeDesc* sd = nm->scope_desc_at( pc);
2464 char buffer[8];
2465 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2466 size_t len = strlen(buffer);
2467 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2468 while (found != NULL) {
2469 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2470 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2471 // Check that the bci found is bracketed by terminators.
2472 break;
2473 }
2474 found = strstr(found + 1, buffer);
2475 }
2476 if (!found) {
2477 continue;
2478 }
2479 }
2480
2481 if (DebugDeoptimization && !deopt) {
2482 deopt = true; // One-time only print before deopt
2483 tty->print_cr("[BEFORE Deoptimization]");
2484 trace_frames();
2485 trace_stack();
2486 }
2487 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2488 }
2489 }
2490
2491 if (DebugDeoptimization && deopt) {
2492 tty->print_cr("[AFTER Deoptimization]");
2493 trace_frames();
2494 }
2495 }
2496
2497
2498 // Make zombies
2499 void JavaThread::make_zombies() {
2500 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2501 if (fst.current()->can_be_deoptimized()) {
2502 // it is a Java nmethod
2503 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2504 nm->make_not_entrant();
2505 }
2506 }
2507 }
2508 #endif // PRODUCT
2509
2510
2511 void JavaThread::deoptimized_wrt_marked_nmethods() {
2512 if (!has_last_Java_frame()) return;
2513 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2514 StackFrameStream fst(this, UseBiasedLocking);
2515 for(; !fst.is_done(); fst.next()) {
2516 if (fst.current()->should_be_deoptimized()) {
2517 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2518 }
2519 }
2520 }
2521
2522
2523 // GC support
2524 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2525
2526 void JavaThread::gc_epilogue() {
2527 frames_do(frame_gc_epilogue);
2528 }
2529
2530
2531 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2532
2533 void JavaThread::gc_prologue() {
2534 frames_do(frame_gc_prologue);
2535 }
2536
2537 // If the caller is a NamedThread, then remember, in the current scope,
2538 // the given JavaThread in its _processed_thread field.
2539 class RememberProcessedThread: public StackObj {
2540 NamedThread* _cur_thr;
2541 public:
2542 RememberProcessedThread(JavaThread* jthr) {
2543 Thread* thread = Thread::current();
2544 if (thread->is_Named_thread()) {
2545 _cur_thr = (NamedThread *)thread;
2546 _cur_thr->set_processed_thread(jthr);
2547 } else {
2548 _cur_thr = NULL;
2549 }
2550 }
2551
2552 ~RememberProcessedThread() {
2553 if (_cur_thr) {
2554 _cur_thr->set_processed_thread(NULL);
2555 }
2556 }
2557 };
2558
2559 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2560 // Verify that the deferred card marks have been flushed.
2561 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2562
2563 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2564 // since there may be more than one thread using each ThreadProfiler.
2565
2566 // Traverse the GCHandles
2567 Thread::oops_do(f, cf);
2568
2569 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2570 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2571
2572 if (has_last_Java_frame()) {
2573 // Record JavaThread to GC thread
2574 RememberProcessedThread rpt(this);
2575
2576 // Traverse the privileged stack
2577 if (_privileged_stack_top != NULL) {
2578 _privileged_stack_top->oops_do(f);
2579 }
2580
2581 // traverse the registered growable array
2582 if (_array_for_gc != NULL) {
2583 for (int index = 0; index < _array_for_gc->length(); index++) {
2584 f->do_oop(_array_for_gc->adr_at(index));
2585 }
2586 }
2587
2588 // Traverse the monitor chunks
2589 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2590 chunk->oops_do(f);
2591 }
2592
2593 // Traverse the execution stack
2594 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2595 fst.current()->oops_do(f, cf, fst.register_map());
2596 }
2597 }
2598
2599 // callee_target is never live across a gc point so NULL it here should
2600 // it still contain a methdOop.
2601
2602 set_callee_target(NULL);
2603
2604 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2605 // If we have deferred set_locals there might be oops waiting to be
2606 // written
2607 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2608 if (list != NULL) {
2609 for (int i = 0; i < list->length(); i++) {
2610 list->at(i)->oops_do(f);
2611 }
2612 }
2613
2614 // Traverse instance variables at the end since the GC may be moving things
2615 // around using this function
2616 f->do_oop((oop*) &_threadObj);
2617 f->do_oop((oop*) &_vm_result);
2618 f->do_oop((oop*) &_vm_result_2);
2619 f->do_oop((oop*) &_exception_oop);
2620 f->do_oop((oop*) &_pending_async_exception);
2621
2622 if (jvmti_thread_state() != NULL) {
2623 jvmti_thread_state()->oops_do(f);
2624 }
2625 }
2626
2627 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2628 Thread::nmethods_do(cf); // (super method is a no-op)
2629
2630 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2631 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2632
2633 if (has_last_Java_frame()) {
2634 // Traverse the execution stack
2635 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2636 fst.current()->nmethods_do(cf);
2637 }
2638 }
2639 }
2640
2641 // Printing
2642 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2643 switch (_thread_state) {
2644 case _thread_uninitialized: return "_thread_uninitialized";
2645 case _thread_new: return "_thread_new";
2646 case _thread_new_trans: return "_thread_new_trans";
2647 case _thread_in_native: return "_thread_in_native";
2648 case _thread_in_native_trans: return "_thread_in_native_trans";
2649 case _thread_in_vm: return "_thread_in_vm";
2650 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2651 case _thread_in_Java: return "_thread_in_Java";
2652 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2653 case _thread_blocked: return "_thread_blocked";
2654 case _thread_blocked_trans: return "_thread_blocked_trans";
2655 default: return "unknown thread state";
2656 }
2657 }
2658
2659 #ifndef PRODUCT
2660 void JavaThread::print_thread_state_on(outputStream *st) const {
2661 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2662 };
2663 void JavaThread::print_thread_state() const {
2664 print_thread_state_on(tty);
2665 };
2666 #endif // PRODUCT
2667
2668 // Called by Threads::print() for VM_PrintThreads operation
2669 void JavaThread::print_on(outputStream *st) const {
2670 st->print("\"%s\" ", get_thread_name());
2671 oop thread_oop = threadObj();
2672 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2673 Thread::print_on(st);
2674 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2675 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2676 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2677 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2678 }
2679 #ifndef PRODUCT
2680 print_thread_state_on(st);
2681 _safepoint_state->print_on(st);
2682 #endif // PRODUCT
2683 }
2684
2685 // Called by fatal error handler. The difference between this and
2686 // JavaThread::print() is that we can't grab lock or allocate memory.
2687 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2688 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2689 oop thread_obj = threadObj();
2690 if (thread_obj != NULL) {
2691 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2692 }
2693 st->print(" [");
2694 st->print("%s", _get_thread_state_name(_thread_state));
2695 if (osthread()) {
2696 st->print(", id=%d", osthread()->thread_id());
2697 }
2698 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2699 _stack_base - _stack_size, _stack_base);
2700 st->print("]");
2701 return;
2702 }
2703
2704 // Verification
2705
2706 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2707
2708 void JavaThread::verify() {
2709 // Verify oops in the thread.
2710 oops_do(&VerifyOopClosure::verify_oop, NULL);
2711
2712 // Verify the stack frames.
2713 frames_do(frame_verify);
2714 }
2715
2716 // CR 6300358 (sub-CR 2137150)
2717 // Most callers of this method assume that it can't return NULL but a
2718 // thread may not have a name whilst it is in the process of attaching to
2719 // the VM - see CR 6412693, and there are places where a JavaThread can be
2720 // seen prior to having it's threadObj set (eg JNI attaching threads and
2721 // if vm exit occurs during initialization). These cases can all be accounted
2722 // for such that this method never returns NULL.
2723 const char* JavaThread::get_thread_name() const {
2724 #ifdef ASSERT
2725 // early safepoints can hit while current thread does not yet have TLS
2726 if (!SafepointSynchronize::is_at_safepoint()) {
2727 Thread *cur = Thread::current();
2728 if (!(cur->is_Java_thread() && cur == this)) {
2729 // Current JavaThreads are allowed to get their own name without
2730 // the Threads_lock.
2731 assert_locked_or_safepoint(Threads_lock);
2732 }
2733 }
2734 #endif // ASSERT
2735 return get_thread_name_string();
2736 }
2737
2738 // Returns a non-NULL representation of this thread's name, or a suitable
2739 // descriptive string if there is no set name
2740 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2741 const char* name_str;
2742 oop thread_obj = threadObj();
2743 if (thread_obj != NULL) {
2744 typeArrayOop name = java_lang_Thread::name(thread_obj);
2745 if (name != NULL) {
2746 if (buf == NULL) {
2747 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2748 }
2749 else {
2750 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2751 }
2752 }
2753 else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2754 name_str = "<no-name - thread is attaching>";
2755 }
2756 else {
2757 name_str = Thread::name();
2758 }
2759 }
2760 else {
2761 name_str = Thread::name();
2762 }
2763 assert(name_str != NULL, "unexpected NULL thread name");
2764 return name_str;
2765 }
2766
2767
2768 const char* JavaThread::get_threadgroup_name() const {
2769 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2770 oop thread_obj = threadObj();
2771 if (thread_obj != NULL) {
2772 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2773 if (thread_group != NULL) {
2774 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2775 // ThreadGroup.name can be null
2776 if (name != NULL) {
2777 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2778 return str;
2779 }
2780 }
2781 }
2782 return NULL;
2783 }
2784
2785 const char* JavaThread::get_parent_name() const {
2786 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2787 oop thread_obj = threadObj();
2788 if (thread_obj != NULL) {
2789 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2790 if (thread_group != NULL) {
2791 oop parent = java_lang_ThreadGroup::parent(thread_group);
2792 if (parent != NULL) {
2793 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2794 // ThreadGroup.name can be null
2795 if (name != NULL) {
2796 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2797 return str;
2798 }
2799 }
2800 }
2801 }
2802 return NULL;
2803 }
2804
2805 ThreadPriority JavaThread::java_priority() const {
2806 oop thr_oop = threadObj();
2807 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2808 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2809 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2810 return priority;
2811 }
2812
2813 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2814
2815 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2816 // Link Java Thread object <-> C++ Thread
2817
2818 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2819 // and put it into a new Handle. The Handle "thread_oop" can then
2820 // be used to pass the C++ thread object to other methods.
2821
2822 // Set the Java level thread object (jthread) field of the
2823 // new thread (a JavaThread *) to C++ thread object using the
2824 // "thread_oop" handle.
2825
2826 // Set the thread field (a JavaThread *) of the
2827 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2828
2829 Handle thread_oop(Thread::current(),
2830 JNIHandles::resolve_non_null(jni_thread));
2831 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2832 "must be initialized");
2833 set_threadObj(thread_oop());
2834 java_lang_Thread::set_thread(thread_oop(), this);
2835
2836 if (prio == NoPriority) {
2837 prio = java_lang_Thread::priority(thread_oop());
2838 assert(prio != NoPriority, "A valid priority should be present");
2839 }
2840
2841 // Push the Java priority down to the native thread; needs Threads_lock
2842 Thread::set_priority(this, prio);
2843
2844 // Add the new thread to the Threads list and set it in motion.
2845 // We must have threads lock in order to call Threads::add.
2846 // It is crucial that we do not block before the thread is
2847 // added to the Threads list for if a GC happens, then the java_thread oop
2848 // will not be visited by GC.
2849 Threads::add(this);
2850 }
2851
2852 oop JavaThread::current_park_blocker() {
2853 // Support for JSR-166 locks
2854 oop thread_oop = threadObj();
2855 if (thread_oop != NULL &&
2856 JDK_Version::current().supports_thread_park_blocker()) {
2857 return java_lang_Thread::park_blocker(thread_oop);
2858 }
2859 return NULL;
2860 }
2861
2862
2863 void JavaThread::print_stack_on(outputStream* st) {
2864 if (!has_last_Java_frame()) return;
2865 ResourceMark rm;
2866 HandleMark hm;
2867
2868 RegisterMap reg_map(this);
2869 vframe* start_vf = last_java_vframe(®_map);
2870 int count = 0;
2871 for (vframe* f = start_vf; f; f = f->sender() ) {
2872 if (f->is_java_frame()) {
2873 javaVFrame* jvf = javaVFrame::cast(f);
2874 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2875
2876 // Print out lock information
2877 if (JavaMonitorsInStackTrace) {
2878 jvf->print_lock_info_on(st, count);
2879 }
2880 } else {
2881 // Ignore non-Java frames
2882 }
2883
2884 // Bail-out case for too deep stacks
2885 count++;
2886 if (MaxJavaStackTraceDepth == count) return;
2887 }
2888 }
2889
2890
2891 // JVMTI PopFrame support
2892 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2893 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2894 if (in_bytes(size_in_bytes) != 0) {
2895 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2896 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2897 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2898 }
2899 }
2900
2901 void* JavaThread::popframe_preserved_args() {
2902 return _popframe_preserved_args;
2903 }
2904
2905 ByteSize JavaThread::popframe_preserved_args_size() {
2906 return in_ByteSize(_popframe_preserved_args_size);
2907 }
2908
2909 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2910 int sz = in_bytes(popframe_preserved_args_size());
2911 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2912 return in_WordSize(sz / wordSize);
2913 }
2914
2915 void JavaThread::popframe_free_preserved_args() {
2916 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2917 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2918 _popframe_preserved_args = NULL;
2919 _popframe_preserved_args_size = 0;
2920 }
2921
2922 #ifndef PRODUCT
2923
2924 void JavaThread::trace_frames() {
2925 tty->print_cr("[Describe stack]");
2926 int frame_no = 1;
2927 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2928 tty->print(" %d. ", frame_no++);
2929 fst.current()->print_value_on(tty,this);
2930 tty->cr();
2931 }
2932 }
2933
2934 class PrintAndVerifyOopClosure: public OopClosure {
2935 protected:
2936 template <class T> inline void do_oop_work(T* p) {
2937 oop obj = oopDesc::load_decode_heap_oop(p);
2938 if (obj == NULL) return;
2939 tty->print(INTPTR_FORMAT ": ", p);
2940 if (obj->is_oop_or_null()) {
2941 if (obj->is_objArray()) {
2942 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
2943 } else {
2944 obj->print();
2945 }
2946 } else {
2947 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
2948 }
2949 tty->cr();
2950 }
2951 public:
2952 virtual void do_oop(oop* p) { do_oop_work(p); }
2953 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2954 };
2955
2956
2957 static void oops_print(frame* f, const RegisterMap *map) {
2958 PrintAndVerifyOopClosure print;
2959 f->print_value();
2960 f->oops_do(&print, NULL, (RegisterMap*)map);
2961 }
2962
2963 // Print our all the locations that contain oops and whether they are
2964 // valid or not. This useful when trying to find the oldest frame
2965 // where an oop has gone bad since the frame walk is from youngest to
2966 // oldest.
2967 void JavaThread::trace_oops() {
2968 tty->print_cr("[Trace oops]");
2969 frames_do(oops_print);
2970 }
2971
2972
2973 #ifdef ASSERT
2974 // Print or validate the layout of stack frames
2975 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2976 ResourceMark rm;
2977 PRESERVE_EXCEPTION_MARK;
2978 FrameValues values;
2979 int frame_no = 0;
2980 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
2981 fst.current()->describe(values, ++frame_no);
2982 if (depth == frame_no) break;
2983 }
2984 if (validate_only) {
2985 values.validate();
2986 } else {
2987 tty->print_cr("[Describe stack layout]");
2988 values.print(this);
2989 }
2990 }
2991 #endif
2992
2993 void JavaThread::trace_stack_from(vframe* start_vf) {
2994 ResourceMark rm;
2995 int vframe_no = 1;
2996 for (vframe* f = start_vf; f; f = f->sender() ) {
2997 if (f->is_java_frame()) {
2998 javaVFrame::cast(f)->print_activation(vframe_no++);
2999 } else {
3000 f->print();
3001 }
3002 if (vframe_no > StackPrintLimit) {
3003 tty->print_cr("...<more frames>...");
3004 return;
3005 }
3006 }
3007 }
3008
3009
3010 void JavaThread::trace_stack() {
3011 if (!has_last_Java_frame()) return;
3012 ResourceMark rm;
3013 HandleMark hm;
3014 RegisterMap reg_map(this);
3015 trace_stack_from(last_java_vframe(®_map));
3016 }
3017
3018
3019 #endif // PRODUCT
3020
3021
3022 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3023 assert(reg_map != NULL, "a map must be given");
3024 frame f = last_frame();
3025 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3026 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3027 }
3028 return NULL;
3029 }
3030
3031
3032 klassOop JavaThread::security_get_caller_class(int depth) {
3033 vframeStream vfst(this);
3034 vfst.security_get_caller_frame(depth);
3035 if (!vfst.at_end()) {
3036 return vfst.method()->method_holder();
3037 }
3038 return NULL;
3039 }
3040
3041 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3042 assert(thread->is_Compiler_thread(), "must be compiler thread");
3043 CompileBroker::compiler_thread_loop();
3044 }
3045
3046 // Create a CompilerThread
3047 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3048 : JavaThread(&compiler_thread_entry) {
3049 _env = NULL;
3050 _log = NULL;
3051 _task = NULL;
3052 _queue = queue;
3053 _counters = counters;
3054 _buffer_blob = NULL;
3055 _scanned_nmethod = NULL;
3056
3057 #ifndef PRODUCT
3058 _ideal_graph_printer = NULL;
3059 #endif
3060 }
3061
3062 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3063 JavaThread::oops_do(f, cf);
3064 if (_scanned_nmethod != NULL && cf != NULL) {
3065 // Safepoints can occur when the sweeper is scanning an nmethod so
3066 // process it here to make sure it isn't unloaded in the middle of
3067 // a scan.
3068 cf->do_code_blob(_scanned_nmethod);
3069 }
3070 }
3071
3072 // ======= Threads ========
3073
3074 // The Threads class links together all active threads, and provides
3075 // operations over all threads. It is protected by its own Mutex
3076 // lock, which is also used in other contexts to protect thread
3077 // operations from having the thread being operated on from exiting
3078 // and going away unexpectedly (e.g., safepoint synchronization)
3079
3080 JavaThread* Threads::_thread_list = NULL;
3081 int Threads::_number_of_threads = 0;
3082 int Threads::_number_of_non_daemon_threads = 0;
3083 int Threads::_return_code = 0;
3084 size_t JavaThread::_stack_size_at_create = 0;
3085
3086 // All JavaThreads
3087 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3088
3089 void os_stream();
3090
3091 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3092 void Threads::threads_do(ThreadClosure* tc) {
3093 assert_locked_or_safepoint(Threads_lock);
3094 // ALL_JAVA_THREADS iterates through all JavaThreads
3095 ALL_JAVA_THREADS(p) {
3096 tc->do_thread(p);
3097 }
3098 // Someday we could have a table or list of all non-JavaThreads.
3099 // For now, just manually iterate through them.
3100 tc->do_thread(VMThread::vm_thread());
3101 Universe::heap()->gc_threads_do(tc);
3102 WatcherThread *wt = WatcherThread::watcher_thread();
3103 // Strictly speaking, the following NULL check isn't sufficient to make sure
3104 // the data for WatcherThread is still valid upon being examined. However,
3105 // considering that WatchThread terminates when the VM is on the way to
3106 // exit at safepoint, the chance of the above is extremely small. The right
3107 // way to prevent termination of WatcherThread would be to acquire
3108 // Terminator_lock, but we can't do that without violating the lock rank
3109 // checking in some cases.
3110 if (wt != NULL)
3111 tc->do_thread(wt);
3112
3113 // If CompilerThreads ever become non-JavaThreads, add them here
3114 }
3115
3116 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3117
3118 extern void JDK_Version_init();
3119
3120 // Check version
3121 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3122
3123 // Initialize the output stream module
3124 ostream_init();
3125
3126 // Process java launcher properties.
3127 Arguments::process_sun_java_launcher_properties(args);
3128
3129 // Initialize the os module before using TLS
3130 os::init();
3131
3132 // Initialize system properties.
3133 Arguments::init_system_properties();
3134
3135 // So that JDK version can be used as a discrimintor when parsing arguments
3136 JDK_Version_init();
3137
3138 // Update/Initialize System properties after JDK version number is known
3139 Arguments::init_version_specific_system_properties();
3140
3141 // Parse arguments
3142 jint parse_result = Arguments::parse(args);
3143 if (parse_result != JNI_OK) return parse_result;
3144
3145 if (PauseAtStartup) {
3146 os::pause();
3147 }
3148
3149 #ifndef USDT2
3150 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3151 #else /* USDT2 */
3152 HOTSPOT_VM_INIT_BEGIN();
3153 #endif /* USDT2 */
3154
3155 // Record VM creation timing statistics
3156 TraceVmCreationTime create_vm_timer;
3157 create_vm_timer.start();
3158
3159 // Timing (must come after argument parsing)
3160 TraceTime timer("Create VM", TraceStartupTime);
3161
3162 // Initialize the os module after parsing the args
3163 jint os_init_2_result = os::init_2();
3164 if (os_init_2_result != JNI_OK) return os_init_2_result;
3165
3166 // Initialize output stream logging
3167 ostream_init_log();
3168
3169 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3170 // Must be before create_vm_init_agents()
3171 if (Arguments::init_libraries_at_startup()) {
3172 convert_vm_init_libraries_to_agents();
3173 }
3174
3175 // Launch -agentlib/-agentpath and converted -Xrun agents
3176 if (Arguments::init_agents_at_startup()) {
3177 create_vm_init_agents();
3178 }
3179
3180 // Initialize Threads state
3181 _thread_list = NULL;
3182 _number_of_threads = 0;
3183 _number_of_non_daemon_threads = 0;
3184
3185 // Initialize TLS
3186 ThreadLocalStorage::init();
3187
3188 // Initialize global data structures and create system classes in heap
3189 vm_init_globals();
3190
3191 // Attach the main thread to this os thread
3192 JavaThread* main_thread = new JavaThread();
3193 main_thread->set_thread_state(_thread_in_vm);
3194 // must do this before set_active_handles and initialize_thread_local_storage
3195 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3196 // change the stack size recorded here to one based on the java thread
3197 // stacksize. This adjusted size is what is used to figure the placement
3198 // of the guard pages.
3199 main_thread->record_stack_base_and_size();
3200 main_thread->initialize_thread_local_storage();
3201
3202 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3203
3204 if (!main_thread->set_as_starting_thread()) {
3205 vm_shutdown_during_initialization(
3206 "Failed necessary internal allocation. Out of swap space");
3207 delete main_thread;
3208 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3209 return JNI_ENOMEM;
3210 }
3211
3212 // Enable guard page *after* os::create_main_thread(), otherwise it would
3213 // crash Linux VM, see notes in os_linux.cpp.
3214 main_thread->create_stack_guard_pages();
3215
3216 // Initialize Java-Level synchronization subsystem
3217 ObjectMonitor::Initialize() ;
3218
3219 // Initialize global modules
3220 jint status = init_globals();
3221 if (status != JNI_OK) {
3222 delete main_thread;
3223 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3224 return status;
3225 }
3226
3227 // Should be done after the heap is fully created
3228 main_thread->cache_global_variables();
3229
3230 HandleMark hm;
3231
3232 { MutexLocker mu(Threads_lock);
3233 Threads::add(main_thread);
3234 }
3235
3236 // Any JVMTI raw monitors entered in onload will transition into
3237 // real raw monitor. VM is setup enough here for raw monitor enter.
3238 JvmtiExport::transition_pending_onload_raw_monitors();
3239
3240 if (VerifyBeforeGC &&
3241 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3242 Universe::heap()->prepare_for_verify();
3243 Universe::verify(); // make sure we're starting with a clean slate
3244 }
3245
3246 // Create the VMThread
3247 { TraceTime timer("Start VMThread", TraceStartupTime);
3248 VMThread::create();
3249 Thread* vmthread = VMThread::vm_thread();
3250
3251 if (!os::create_thread(vmthread, os::vm_thread))
3252 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3253
3254 // Wait for the VM thread to become ready, and VMThread::run to initialize
3255 // Monitors can have spurious returns, must always check another state flag
3256 {
3257 MutexLocker ml(Notify_lock);
3258 os::start_thread(vmthread);
3259 while (vmthread->active_handles() == NULL) {
3260 Notify_lock->wait();
3261 }
3262 }
3263 }
3264
3265 assert (Universe::is_fully_initialized(), "not initialized");
3266 EXCEPTION_MARK;
3267
3268 // At this point, the Universe is initialized, but we have not executed
3269 // any byte code. Now is a good time (the only time) to dump out the
3270 // internal state of the JVM for sharing.
3271
3272 if (DumpSharedSpaces) {
3273 Universe::heap()->preload_and_dump(CHECK_0);
3274 ShouldNotReachHere();
3275 }
3276
3277 // Always call even when there are not JVMTI environments yet, since environments
3278 // may be attached late and JVMTI must track phases of VM execution
3279 JvmtiExport::enter_start_phase();
3280
3281 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3282 JvmtiExport::post_vm_start();
3283
3284 {
3285 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3286
3287 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3288 create_vm_init_libraries();
3289 }
3290
3291 if (InitializeJavaLangString) {
3292 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3293 } else {
3294 warning("java.lang.String not initialized");
3295 }
3296
3297 if (AggressiveOpts) {
3298 {
3299 // Forcibly initialize java/util/HashMap and mutate the private
3300 // static final "frontCacheEnabled" field before we start creating instances
3301 #ifdef ASSERT
3302 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3303 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3304 #endif
3305 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3306 KlassHandle k = KlassHandle(THREAD, k_o);
3307 guarantee(k.not_null(), "Must find java/util/HashMap");
3308 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3309 ik->initialize(CHECK_0);
3310 fieldDescriptor fd;
3311 // Possible we might not find this field; if so, don't break
3312 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3313 k()->java_mirror()->bool_field_put(fd.offset(), true);
3314 }
3315 }
3316
3317 if (UseStringCache) {
3318 // Forcibly initialize java/lang/StringValue and mutate the private
3319 // static final "stringCacheEnabled" field before we start creating instances
3320 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3321 // Possible that StringValue isn't present: if so, silently don't break
3322 if (k_o != NULL) {
3323 KlassHandle k = KlassHandle(THREAD, k_o);
3324 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3325 ik->initialize(CHECK_0);
3326 fieldDescriptor fd;
3327 // Possible we might not find this field: if so, silently don't break
3328 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3329 k()->java_mirror()->bool_field_put(fd.offset(), true);
3330 }
3331 }
3332 }
3333 }
3334
3335 // Initialize java_lang.System (needed before creating the thread)
3336 if (InitializeJavaLangSystem) {
3337 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3338 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3339 Handle thread_group = create_initial_thread_group(CHECK_0);
3340 Universe::set_main_thread_group(thread_group());
3341 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3342 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3343 main_thread->set_threadObj(thread_object);
3344 // Set thread status to running since main thread has
3345 // been started and running.
3346 java_lang_Thread::set_thread_status(thread_object,
3347 java_lang_Thread::RUNNABLE);
3348
3349 // The VM preresolve methods to these classes. Make sure that get initialized
3350 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3351 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3352 // The VM creates & returns objects of this class. Make sure it's initialized.
3353 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3354 call_initializeSystemClass(CHECK_0);
3355 } else {
3356 warning("java.lang.System not initialized");
3357 }
3358
3359 // an instance of OutOfMemory exception has been allocated earlier
3360 if (InitializeJavaLangExceptionsErrors) {
3361 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3362 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3363 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3364 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3365 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3366 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3367 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3368 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), 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 warning("java.lang.IllegalArgumentException has not been initialized");
3377 }
3378 }
3379
3380 // See : bugid 4211085.
3381 // Background : the static initializer of java.lang.Compiler tries to read
3382 // property"java.compiler" and read & write property "java.vm.info".
3383 // When a security manager is installed through the command line
3384 // option "-Djava.security.manager", the above properties are not
3385 // readable and the static initializer for java.lang.Compiler fails
3386 // resulting in a NoClassDefFoundError. This can happen in any
3387 // user code which calls methods in java.lang.Compiler.
3388 // Hack : the hack is to pre-load and initialize this class, so that only
3389 // system domains are on the stack when the properties are read.
3390 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3391 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3392 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3393 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3394 // Once that is done, we should remove this hack.
3395 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3396
3397 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3398 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3399 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3400 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3401 // This should also be taken out as soon as 4211383 gets fixed.
3402 reset_vm_info_property(CHECK_0);
3403
3404 quicken_jni_functions();
3405
3406 // Must be run after init_ft which initializes ft_enabled
3407 if (TRACE_INITIALIZE() != JNI_OK) {
3408 vm_exit_during_initialization("Failed to initialize tracing backend");
3409 }
3410
3411 // Set flag that basic initialization has completed. Used by exceptions and various
3412 // debug stuff, that does not work until all basic classes have been initialized.
3413 set_init_completed();
3414
3415 #ifndef USDT2
3416 HS_DTRACE_PROBE(hotspot, vm__init__end);
3417 #else /* USDT2 */
3418 HOTSPOT_VM_INIT_END();
3419 #endif /* USDT2 */
3420
3421 // record VM initialization completion time
3422 Management::record_vm_init_completed();
3423
3424 // Compute system loader. Note that this has to occur after set_init_completed, since
3425 // valid exceptions may be thrown in the process.
3426 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3427 // set_init_completed has just been called, causing exceptions not to be shortcut
3428 // anymore. We call vm_exit_during_initialization directly instead.
3429 SystemDictionary::compute_java_system_loader(THREAD);
3430 if (HAS_PENDING_EXCEPTION) {
3431 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3432 }
3433
3434 #ifndef SERIALGC
3435 // Support for ConcurrentMarkSweep. This should be cleaned up
3436 // and better encapsulated. The ugly nested if test would go away
3437 // once things are properly refactored. XXX YSR
3438 if (UseConcMarkSweepGC || UseG1GC) {
3439 if (UseConcMarkSweepGC) {
3440 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3441 } else {
3442 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3443 }
3444 if (HAS_PENDING_EXCEPTION) {
3445 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3446 }
3447 }
3448 #endif // SERIALGC
3449
3450 // Always call even when there are not JVMTI environments yet, since environments
3451 // may be attached late and JVMTI must track phases of VM execution
3452 JvmtiExport::enter_live_phase();
3453
3454 // Signal Dispatcher needs to be started before VMInit event is posted
3455 os::signal_init();
3456
3457 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3458 if (!DisableAttachMechanism) {
3459 if (StartAttachListener || AttachListener::init_at_startup()) {
3460 AttachListener::init();
3461 }
3462 }
3463
3464 // Launch -Xrun agents
3465 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3466 // back-end can launch with -Xdebug -Xrunjdwp.
3467 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3468 create_vm_init_libraries();
3469 }
3470
3471 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3472 JvmtiExport::post_vm_initialized();
3473
3474 if (!TRACE_START()) {
3475 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3476 }
3477
3478 if (CleanChunkPoolAsync) {
3479 Chunk::start_chunk_pool_cleaner_task();
3480 }
3481
3482 // initialize compiler(s)
3483 CompileBroker::compilation_init();
3484
3485 Management::initialize(THREAD);
3486 if (HAS_PENDING_EXCEPTION) {
3487 // management agent fails to start possibly due to
3488 // configuration problem and is responsible for printing
3489 // stack trace if appropriate. Simply exit VM.
3490 vm_exit(1);
3491 }
3492
3493 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3494 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3495 if (MemProfiling) MemProfiler::engage();
3496 StatSampler::engage();
3497 if (CheckJNICalls) JniPeriodicChecker::engage();
3498
3499 BiasedLocking::init();
3500
3501 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3502 call_postVMInitHook(THREAD);
3503 // The Java side of PostVMInitHook.run must deal with all
3504 // exceptions and provide means of diagnosis.
3505 if (HAS_PENDING_EXCEPTION) {
3506 CLEAR_PENDING_EXCEPTION;
3507 }
3508 }
3509
3510 // Start up the WatcherThread if there are any periodic tasks
3511 // NOTE: All PeriodicTasks should be registered by now. If they
3512 // aren't, late joiners might appear to start slowly (we might
3513 // take a while to process their first tick).
3514 if (PeriodicTask::num_tasks() > 0) {
3515 WatcherThread::start();
3516 }
3517
3518 // Give os specific code one last chance to start
3519 os::init_3();
3520
3521 create_vm_timer.end();
3522 return JNI_OK;
3523 }
3524
3525 // type for the Agent_OnLoad and JVM_OnLoad entry points
3526 extern "C" {
3527 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3528 }
3529 // Find a command line agent library and return its entry point for
3530 // -agentlib: -agentpath: -Xrun
3531 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3532 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3533 OnLoadEntry_t on_load_entry = NULL;
3534 void *library = agent->os_lib(); // check if we have looked it up before
3535
3536 if (library == NULL) {
3537 char buffer[JVM_MAXPATHLEN];
3538 char ebuf[1024];
3539 const char *name = agent->name();
3540 const char *msg = "Could not find agent library ";
3541
3542 if (agent->is_absolute_path()) {
3543 library = os::dll_load(name, ebuf, sizeof ebuf);
3544 if (library == NULL) {
3545 const char *sub_msg = " in absolute path, with error: ";
3546 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3547 char *buf = NEW_C_HEAP_ARRAY(char, len);
3548 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3549 // If we can't find the agent, exit.
3550 vm_exit_during_initialization(buf, NULL);
3551 FREE_C_HEAP_ARRAY(char, buf);
3552 }
3553 } else {
3554 // Try to load the agent from the standard dll directory
3555 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3556 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3557 #ifdef KERNEL
3558 // Download instrument dll
3559 if (library == NULL && strcmp(name, "instrument") == 0) {
3560 char *props = Arguments::get_kernel_properties();
3561 char *home = Arguments::get_java_home();
3562 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3563 " sun.jkernel.DownloadManager -download client_jvm";
3564 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3565 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3566 jio_snprintf(cmd, length, fmt, home, props);
3567 int status = os::fork_and_exec(cmd);
3568 FreeHeap(props);
3569 if (status == -1) {
3570 warning(cmd);
3571 vm_exit_during_initialization("fork_and_exec failed: %s",
3572 strerror(errno));
3573 }
3574 FREE_C_HEAP_ARRAY(char, cmd);
3575 // when this comes back the instrument.dll should be where it belongs.
3576 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3577 }
3578 #endif // KERNEL
3579 if (library == NULL) { // Try the local directory
3580 char ns[1] = {0};
3581 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3582 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3583 if (library == NULL) {
3584 const char *sub_msg = " on the library path, with error: ";
3585 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3586 char *buf = NEW_C_HEAP_ARRAY(char, len);
3587 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3588 // If we can't find the agent, exit.
3589 vm_exit_during_initialization(buf, NULL);
3590 FREE_C_HEAP_ARRAY(char, buf);
3591 }
3592 }
3593 }
3594 agent->set_os_lib(library);
3595 }
3596
3597 // Find the OnLoad function.
3598 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3599 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3600 if (on_load_entry != NULL) break;
3601 }
3602 return on_load_entry;
3603 }
3604
3605 // Find the JVM_OnLoad entry point
3606 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3607 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3608 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3609 }
3610
3611 // Find the Agent_OnLoad entry point
3612 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3613 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3614 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3615 }
3616
3617 // For backwards compatibility with -Xrun
3618 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3619 // treated like -agentpath:
3620 // Must be called before agent libraries are created
3621 void Threads::convert_vm_init_libraries_to_agents() {
3622 AgentLibrary* agent;
3623 AgentLibrary* next;
3624
3625 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3626 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3627 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3628
3629 // If there is an JVM_OnLoad function it will get called later,
3630 // otherwise see if there is an Agent_OnLoad
3631 if (on_load_entry == NULL) {
3632 on_load_entry = lookup_agent_on_load(agent);
3633 if (on_load_entry != NULL) {
3634 // switch it to the agent list -- so that Agent_OnLoad will be called,
3635 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3636 Arguments::convert_library_to_agent(agent);
3637 } else {
3638 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3639 }
3640 }
3641 }
3642 }
3643
3644 // Create agents for -agentlib: -agentpath: and converted -Xrun
3645 // Invokes Agent_OnLoad
3646 // Called very early -- before JavaThreads exist
3647 void Threads::create_vm_init_agents() {
3648 extern struct JavaVM_ main_vm;
3649 AgentLibrary* agent;
3650
3651 JvmtiExport::enter_onload_phase();
3652 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3653 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3654
3655 if (on_load_entry != NULL) {
3656 // Invoke the Agent_OnLoad function
3657 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3658 if (err != JNI_OK) {
3659 vm_exit_during_initialization("agent library failed to init", agent->name());
3660 }
3661 } else {
3662 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3663 }
3664 }
3665 JvmtiExport::enter_primordial_phase();
3666 }
3667
3668 extern "C" {
3669 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3670 }
3671
3672 void Threads::shutdown_vm_agents() {
3673 // Send any Agent_OnUnload notifications
3674 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3675 extern struct JavaVM_ main_vm;
3676 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3677
3678 // Find the Agent_OnUnload function.
3679 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3680 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3681 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3682
3683 // Invoke the Agent_OnUnload function
3684 if (unload_entry != NULL) {
3685 JavaThread* thread = JavaThread::current();
3686 ThreadToNativeFromVM ttn(thread);
3687 HandleMark hm(thread);
3688 (*unload_entry)(&main_vm);
3689 break;
3690 }
3691 }
3692 }
3693 }
3694
3695 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3696 // Invokes JVM_OnLoad
3697 void Threads::create_vm_init_libraries() {
3698 extern struct JavaVM_ main_vm;
3699 AgentLibrary* agent;
3700
3701 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3702 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3703
3704 if (on_load_entry != NULL) {
3705 // Invoke the JVM_OnLoad function
3706 JavaThread* thread = JavaThread::current();
3707 ThreadToNativeFromVM ttn(thread);
3708 HandleMark hm(thread);
3709 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3710 if (err != JNI_OK) {
3711 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3712 }
3713 } else {
3714 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3715 }
3716 }
3717 }
3718
3719 // Last thread running calls java.lang.Shutdown.shutdown()
3720 void JavaThread::invoke_shutdown_hooks() {
3721 HandleMark hm(this);
3722
3723 // We could get here with a pending exception, if so clear it now.
3724 if (this->has_pending_exception()) {
3725 this->clear_pending_exception();
3726 }
3727
3728 EXCEPTION_MARK;
3729 klassOop k =
3730 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3731 THREAD);
3732 if (k != NULL) {
3733 // SystemDictionary::resolve_or_null will return null if there was
3734 // an exception. If we cannot load the Shutdown class, just don't
3735 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3736 // and finalizers (if runFinalizersOnExit is set) won't be run.
3737 // Note that if a shutdown hook was registered or runFinalizersOnExit
3738 // was called, the Shutdown class would have already been loaded
3739 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3740 instanceKlassHandle shutdown_klass (THREAD, k);
3741 JavaValue result(T_VOID);
3742 JavaCalls::call_static(&result,
3743 shutdown_klass,
3744 vmSymbols::shutdown_method_name(),
3745 vmSymbols::void_method_signature(),
3746 THREAD);
3747 }
3748 CLEAR_PENDING_EXCEPTION;
3749 }
3750
3751 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3752 // the program falls off the end of main(). Another VM exit path is through
3753 // vm_exit() when the program calls System.exit() to return a value or when
3754 // there is a serious error in VM. The two shutdown paths are not exactly
3755 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3756 // and VM_Exit op at VM level.
3757 //
3758 // Shutdown sequence:
3759 // + Wait until we are the last non-daemon thread to execute
3760 // <-- every thing is still working at this moment -->
3761 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3762 // shutdown hooks, run finalizers if finalization-on-exit
3763 // + Call before_exit(), prepare for VM exit
3764 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3765 // currently the only user of this mechanism is File.deleteOnExit())
3766 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3767 // post thread end and vm death events to JVMTI,
3768 // stop signal thread
3769 // + Call JavaThread::exit(), it will:
3770 // > release JNI handle blocks, remove stack guard pages
3771 // > remove this thread from Threads list
3772 // <-- no more Java code from this thread after this point -->
3773 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3774 // the compiler threads at safepoint
3775 // <-- do not use anything that could get blocked by Safepoint -->
3776 // + Disable tracing at JNI/JVM barriers
3777 // + Set _vm_exited flag for threads that are still running native code
3778 // + Delete this thread
3779 // + Call exit_globals()
3780 // > deletes tty
3781 // > deletes PerfMemory resources
3782 // + Return to caller
3783
3784 bool Threads::destroy_vm() {
3785 JavaThread* thread = JavaThread::current();
3786
3787 // Wait until we are the last non-daemon thread to execute
3788 { MutexLocker nu(Threads_lock);
3789 while (Threads::number_of_non_daemon_threads() > 1 )
3790 // This wait should make safepoint checks, wait without a timeout,
3791 // and wait as a suspend-equivalent condition.
3792 //
3793 // Note: If the FlatProfiler is running and this thread is waiting
3794 // for another non-daemon thread to finish, then the FlatProfiler
3795 // is waiting for the external suspend request on this thread to
3796 // complete. wait_for_ext_suspend_completion() will eventually
3797 // timeout, but that takes time. Making this wait a suspend-
3798 // equivalent condition solves that timeout problem.
3799 //
3800 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3801 Mutex::_as_suspend_equivalent_flag);
3802 }
3803
3804 // Hang forever on exit if we are reporting an error.
3805 if (ShowMessageBoxOnError && is_error_reported()) {
3806 os::infinite_sleep();
3807 }
3808 os::wait_for_keypress_at_exit();
3809
3810 if (JDK_Version::is_jdk12x_version()) {
3811 // We are the last thread running, so check if finalizers should be run.
3812 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3813 HandleMark rm(thread);
3814 Universe::run_finalizers_on_exit();
3815 } else {
3816 // run Java level shutdown hooks
3817 thread->invoke_shutdown_hooks();
3818 }
3819
3820 before_exit(thread);
3821
3822 thread->exit(true);
3823
3824 // Stop VM thread.
3825 {
3826 // 4945125 The vm thread comes to a safepoint during exit.
3827 // GC vm_operations can get caught at the safepoint, and the
3828 // heap is unparseable if they are caught. Grab the Heap_lock
3829 // to prevent this. The GC vm_operations will not be able to
3830 // queue until after the vm thread is dead.
3831 // After this point, we'll never emerge out of the safepoint before
3832 // the VM exits, so concurrent GC threads do not need to be explicitly
3833 // stopped; they remain inactive until the process exits.
3834 // Note: some concurrent G1 threads may be running during a safepoint,
3835 // but these will not be accessing the heap, just some G1-specific side
3836 // data structures that are not accessed by any other threads but them
3837 // after this point in a terminal safepoint.
3838
3839 MutexLocker ml(Heap_lock);
3840
3841 VMThread::wait_for_vm_thread_exit();
3842 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3843 VMThread::destroy();
3844 }
3845
3846 // clean up ideal graph printers
3847 #if defined(COMPILER2) && !defined(PRODUCT)
3848 IdealGraphPrinter::clean_up();
3849 #endif
3850
3851 // Now, all Java threads are gone except daemon threads. Daemon threads
3852 // running Java code or in VM are stopped by the Safepoint. However,
3853 // daemon threads executing native code are still running. But they
3854 // will be stopped at native=>Java/VM barriers. Note that we can't
3855 // simply kill or suspend them, as it is inherently deadlock-prone.
3856
3857 #ifndef PRODUCT
3858 // disable function tracing at JNI/JVM barriers
3859 TraceJNICalls = false;
3860 TraceJVMCalls = false;
3861 TraceRuntimeCalls = false;
3862 #endif
3863
3864 VM_Exit::set_vm_exited();
3865
3866 notify_vm_shutdown();
3867
3868 delete thread;
3869
3870 // exit_globals() will delete tty
3871 exit_globals();
3872
3873 return true;
3874 }
3875
3876
3877 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3878 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3879 return is_supported_jni_version(version);
3880 }
3881
3882
3883 jboolean Threads::is_supported_jni_version(jint version) {
3884 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3885 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3886 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3887 return JNI_FALSE;
3888 }
3889
3890
3891 void Threads::add(JavaThread* p, bool force_daemon) {
3892 // The threads lock must be owned at this point
3893 assert_locked_or_safepoint(Threads_lock);
3894
3895 // See the comment for this method in thread.hpp for its purpose and
3896 // why it is called here.
3897 p->initialize_queues();
3898 p->set_next(_thread_list);
3899 _thread_list = p;
3900 _number_of_threads++;
3901 oop threadObj = p->threadObj();
3902 bool daemon = true;
3903 // Bootstrapping problem: threadObj can be null for initial
3904 // JavaThread (or for threads attached via JNI)
3905 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3906 _number_of_non_daemon_threads++;
3907 daemon = false;
3908 }
3909
3910 ThreadService::add_thread(p, daemon);
3911
3912 // Possible GC point.
3913 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3914 }
3915
3916 void Threads::remove(JavaThread* p) {
3917 // Extra scope needed for Thread_lock, so we can check
3918 // that we do not remove thread without safepoint code notice
3919 { MutexLocker ml(Threads_lock);
3920
3921 assert(includes(p), "p must be present");
3922
3923 JavaThread* current = _thread_list;
3924 JavaThread* prev = NULL;
3925
3926 while (current != p) {
3927 prev = current;
3928 current = current->next();
3929 }
3930
3931 if (prev) {
3932 prev->set_next(current->next());
3933 } else {
3934 _thread_list = p->next();
3935 }
3936 _number_of_threads--;
3937 oop threadObj = p->threadObj();
3938 bool daemon = true;
3939 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3940 _number_of_non_daemon_threads--;
3941 daemon = false;
3942
3943 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3944 // on destroy_vm will wake up.
3945 if (number_of_non_daemon_threads() == 1)
3946 Threads_lock->notify_all();
3947 }
3948 ThreadService::remove_thread(p, daemon);
3949
3950 // Make sure that safepoint code disregard this thread. This is needed since
3951 // the thread might mess around with locks after this point. This can cause it
3952 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3953 // of this thread since it is removed from the queue.
3954 p->set_terminated_value();
3955 } // unlock Threads_lock
3956
3957 // Since Events::log uses a lock, we grab it outside the Threads_lock
3958 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
3959 }
3960
3961 // Threads_lock must be held when this is called (or must be called during a safepoint)
3962 bool Threads::includes(JavaThread* p) {
3963 assert(Threads_lock->is_locked(), "sanity check");
3964 ALL_JAVA_THREADS(q) {
3965 if (q == p ) {
3966 return true;
3967 }
3968 }
3969 return false;
3970 }
3971
3972 // Operations on the Threads list for GC. These are not explicitly locked,
3973 // but the garbage collector must provide a safe context for them to run.
3974 // In particular, these things should never be called when the Threads_lock
3975 // is held by some other thread. (Note: the Safepoint abstraction also
3976 // uses the Threads_lock to gurantee this property. It also makes sure that
3977 // all threads gets blocked when exiting or starting).
3978
3979 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3980 ALL_JAVA_THREADS(p) {
3981 p->oops_do(f, cf);
3982 }
3983 VMThread::vm_thread()->oops_do(f, cf);
3984 }
3985
3986 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3987 // Introduce a mechanism allowing parallel threads to claim threads as
3988 // root groups. Overhead should be small enough to use all the time,
3989 // even in sequential code.
3990 SharedHeap* sh = SharedHeap::heap();
3991 // Cannot yet substitute active_workers for n_par_threads
3992 // because of G1CollectedHeap::verify() use of
3993 // SharedHeap::process_strong_roots(). n_par_threads == 0 will
3994 // turn off parallelism in process_strong_roots while active_workers
3995 // is being used for parallelism elsewhere.
3996 bool is_par = sh->n_par_threads() > 0;
3997 assert(!is_par ||
3998 (SharedHeap::heap()->n_par_threads() ==
3999 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4000 int cp = SharedHeap::heap()->strong_roots_parity();
4001 ALL_JAVA_THREADS(p) {
4002 if (p->claim_oops_do(is_par, cp)) {
4003 p->oops_do(f, cf);
4004 }
4005 }
4006 VMThread* vmt = VMThread::vm_thread();
4007 if (vmt->claim_oops_do(is_par, cp)) {
4008 vmt->oops_do(f, cf);
4009 }
4010 }
4011
4012 #ifndef SERIALGC
4013 // Used by ParallelScavenge
4014 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4015 ALL_JAVA_THREADS(p) {
4016 q->enqueue(new ThreadRootsTask(p));
4017 }
4018 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4019 }
4020
4021 // Used by Parallel Old
4022 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4023 ALL_JAVA_THREADS(p) {
4024 q->enqueue(new ThreadRootsMarkingTask(p));
4025 }
4026 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4027 }
4028 #endif // SERIALGC
4029
4030 void Threads::nmethods_do(CodeBlobClosure* cf) {
4031 ALL_JAVA_THREADS(p) {
4032 p->nmethods_do(cf);
4033 }
4034 VMThread::vm_thread()->nmethods_do(cf);
4035 }
4036
4037 void Threads::gc_epilogue() {
4038 ALL_JAVA_THREADS(p) {
4039 p->gc_epilogue();
4040 }
4041 }
4042
4043 void Threads::gc_prologue() {
4044 ALL_JAVA_THREADS(p) {
4045 p->gc_prologue();
4046 }
4047 }
4048
4049 void Threads::deoptimized_wrt_marked_nmethods() {
4050 ALL_JAVA_THREADS(p) {
4051 p->deoptimized_wrt_marked_nmethods();
4052 }
4053 }
4054
4055
4056 // Get count Java threads that are waiting to enter the specified monitor.
4057 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4058 address monitor, bool doLock) {
4059 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4060 "must grab Threads_lock or be at safepoint");
4061 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4062
4063 int i = 0;
4064 {
4065 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4066 ALL_JAVA_THREADS(p) {
4067 if (p->is_Compiler_thread()) continue;
4068
4069 address pending = (address)p->current_pending_monitor();
4070 if (pending == monitor) { // found a match
4071 if (i < count) result->append(p); // save the first count matches
4072 i++;
4073 }
4074 }
4075 }
4076 return result;
4077 }
4078
4079
4080 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4081 assert(doLock ||
4082 Threads_lock->owned_by_self() ||
4083 SafepointSynchronize::is_at_safepoint(),
4084 "must grab Threads_lock or be at safepoint");
4085
4086 // NULL owner means not locked so we can skip the search
4087 if (owner == NULL) return NULL;
4088
4089 {
4090 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4091 ALL_JAVA_THREADS(p) {
4092 // first, see if owner is the address of a Java thread
4093 if (owner == (address)p) return p;
4094 }
4095 }
4096 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
4097 if (UseHeavyMonitors) return NULL;
4098
4099 //
4100 // If we didn't find a matching Java thread and we didn't force use of
4101 // heavyweight monitors, then the owner is the stack address of the
4102 // Lock Word in the owning Java thread's stack.
4103 //
4104 JavaThread* the_owner = NULL;
4105 {
4106 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4107 ALL_JAVA_THREADS(q) {
4108 if (q->is_lock_owned(owner)) {
4109 the_owner = q;
4110 break;
4111 }
4112 }
4113 }
4114 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
4115 return the_owner;
4116 }
4117
4118 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4119 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4120 char buf[32];
4121 st->print_cr(os::local_time_string(buf, sizeof(buf)));
4122
4123 st->print_cr("Full thread dump %s (%s %s):",
4124 Abstract_VM_Version::vm_name(),
4125 Abstract_VM_Version::vm_release(),
4126 Abstract_VM_Version::vm_info_string()
4127 );
4128 st->cr();
4129
4130 #ifndef SERIALGC
4131 // Dump concurrent locks
4132 ConcurrentLocksDump concurrent_locks;
4133 if (print_concurrent_locks) {
4134 concurrent_locks.dump_at_safepoint();
4135 }
4136 #endif // SERIALGC
4137
4138 ALL_JAVA_THREADS(p) {
4139 ResourceMark rm;
4140 p->print_on(st);
4141 if (print_stacks) {
4142 if (internal_format) {
4143 p->trace_stack();
4144 } else {
4145 p->print_stack_on(st);
4146 }
4147 }
4148 st->cr();
4149 #ifndef SERIALGC
4150 if (print_concurrent_locks) {
4151 concurrent_locks.print_locks_on(p, st);
4152 }
4153 #endif // SERIALGC
4154 }
4155
4156 VMThread::vm_thread()->print_on(st);
4157 st->cr();
4158 Universe::heap()->print_gc_threads_on(st);
4159 WatcherThread* wt = WatcherThread::watcher_thread();
4160 if (wt != NULL) wt->print_on(st);
4161 st->cr();
4162 CompileBroker::print_compiler_threads_on(st);
4163 st->flush();
4164 }
4165
4166 // Threads::print_on_error() is called by fatal error handler. It's possible
4167 // that VM is not at safepoint and/or current thread is inside signal handler.
4168 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4169 // memory (even in resource area), it might deadlock the error handler.
4170 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4171 bool found_current = false;
4172 st->print_cr("Java Threads: ( => current thread )");
4173 ALL_JAVA_THREADS(thread) {
4174 bool is_current = (current == thread);
4175 found_current = found_current || is_current;
4176
4177 st->print("%s", is_current ? "=>" : " ");
4178
4179 st->print(PTR_FORMAT, thread);
4180 st->print(" ");
4181 thread->print_on_error(st, buf, buflen);
4182 st->cr();
4183 }
4184 st->cr();
4185
4186 st->print_cr("Other Threads:");
4187 if (VMThread::vm_thread()) {
4188 bool is_current = (current == VMThread::vm_thread());
4189 found_current = found_current || is_current;
4190 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4191
4192 st->print(PTR_FORMAT, VMThread::vm_thread());
4193 st->print(" ");
4194 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4195 st->cr();
4196 }
4197 WatcherThread* wt = WatcherThread::watcher_thread();
4198 if (wt != NULL) {
4199 bool is_current = (current == wt);
4200 found_current = found_current || is_current;
4201 st->print("%s", is_current ? "=>" : " ");
4202
4203 st->print(PTR_FORMAT, wt);
4204 st->print(" ");
4205 wt->print_on_error(st, buf, buflen);
4206 st->cr();
4207 }
4208 if (!found_current) {
4209 st->cr();
4210 st->print("=>" PTR_FORMAT " (exited) ", current);
4211 current->print_on_error(st, buf, buflen);
4212 st->cr();
4213 }
4214 }
4215
4216 // Internal SpinLock and Mutex
4217 // Based on ParkEvent
4218
4219 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4220 //
4221 // We employ SpinLocks _only for low-contention, fixed-length
4222 // short-duration critical sections where we're concerned
4223 // about native mutex_t or HotSpot Mutex:: latency.
4224 // The mux construct provides a spin-then-block mutual exclusion
4225 // mechanism.
4226 //
4227 // Testing has shown that contention on the ListLock guarding gFreeList
4228 // is common. If we implement ListLock as a simple SpinLock it's common
4229 // for the JVM to devolve to yielding with little progress. This is true
4230 // despite the fact that the critical sections protected by ListLock are
4231 // extremely short.
4232 //
4233 // TODO-FIXME: ListLock should be of type SpinLock.
4234 // We should make this a 1st-class type, integrated into the lock
4235 // hierarchy as leaf-locks. Critically, the SpinLock structure
4236 // should have sufficient padding to avoid false-sharing and excessive
4237 // cache-coherency traffic.
4238
4239
4240 typedef volatile int SpinLockT ;
4241
4242 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4243 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4244 return ; // normal fast-path return
4245 }
4246
4247 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4248 TEVENT (SpinAcquire - ctx) ;
4249 int ctr = 0 ;
4250 int Yields = 0 ;
4251 for (;;) {
4252 while (*adr != 0) {
4253 ++ctr ;
4254 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4255 if (Yields > 5) {
4256 // Consider using a simple NakedSleep() instead.
4257 // Then SpinAcquire could be called by non-JVM threads
4258 Thread::current()->_ParkEvent->park(1) ;
4259 } else {
4260 os::NakedYield() ;
4261 ++Yields ;
4262 }
4263 } else {
4264 SpinPause() ;
4265 }
4266 }
4267 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4268 }
4269 }
4270
4271 void Thread::SpinRelease (volatile int * adr) {
4272 assert (*adr != 0, "invariant") ;
4273 OrderAccess::fence() ; // guarantee at least release consistency.
4274 // Roach-motel semantics.
4275 // It's safe if subsequent LDs and STs float "up" into the critical section,
4276 // but prior LDs and STs within the critical section can't be allowed
4277 // to reorder or float past the ST that releases the lock.
4278 *adr = 0 ;
4279 }
4280
4281 // muxAcquire and muxRelease:
4282 //
4283 // * muxAcquire and muxRelease support a single-word lock-word construct.
4284 // The LSB of the word is set IFF the lock is held.
4285 // The remainder of the word points to the head of a singly-linked list
4286 // of threads blocked on the lock.
4287 //
4288 // * The current implementation of muxAcquire-muxRelease uses its own
4289 // dedicated Thread._MuxEvent instance. If we're interested in
4290 // minimizing the peak number of extant ParkEvent instances then
4291 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4292 // as certain invariants were satisfied. Specifically, care would need
4293 // to be taken with regards to consuming unpark() "permits".
4294 // A safe rule of thumb is that a thread would never call muxAcquire()
4295 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4296 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4297 // consume an unpark() permit intended for monitorenter, for instance.
4298 // One way around this would be to widen the restricted-range semaphore
4299 // implemented in park(). Another alternative would be to provide
4300 // multiple instances of the PlatformEvent() for each thread. One
4301 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4302 //
4303 // * Usage:
4304 // -- Only as leaf locks
4305 // -- for short-term locking only as muxAcquire does not perform
4306 // thread state transitions.
4307 //
4308 // Alternatives:
4309 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4310 // but with parking or spin-then-park instead of pure spinning.
4311 // * Use Taura-Oyama-Yonenzawa locks.
4312 // * It's possible to construct a 1-0 lock if we encode the lockword as
4313 // (List,LockByte). Acquire will CAS the full lockword while Release
4314 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4315 // acquiring threads use timers (ParkTimed) to detect and recover from
4316 // the stranding window. Thread/Node structures must be aligned on 256-byte
4317 // boundaries by using placement-new.
4318 // * Augment MCS with advisory back-link fields maintained with CAS().
4319 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4320 // The validity of the backlinks must be ratified before we trust the value.
4321 // If the backlinks are invalid the exiting thread must back-track through the
4322 // the forward links, which are always trustworthy.
4323 // * Add a successor indication. The LockWord is currently encoded as
4324 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4325 // to provide the usual futile-wakeup optimization.
4326 // See RTStt for details.
4327 // * Consider schedctl.sc_nopreempt to cover the critical section.
4328 //
4329
4330
4331 typedef volatile intptr_t MutexT ; // Mux Lock-word
4332 enum MuxBits { LOCKBIT = 1 } ;
4333
4334 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4335 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4336 if (w == 0) return ;
4337 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4338 return ;
4339 }
4340
4341 TEVENT (muxAcquire - Contention) ;
4342 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4343 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4344 for (;;) {
4345 int its = (os::is_MP() ? 100 : 0) + 1 ;
4346
4347 // Optional spin phase: spin-then-park strategy
4348 while (--its >= 0) {
4349 w = *Lock ;
4350 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4351 return ;
4352 }
4353 }
4354
4355 Self->reset() ;
4356 Self->OnList = intptr_t(Lock) ;
4357 // The following fence() isn't _strictly necessary as the subsequent
4358 // CAS() both serializes execution and ratifies the fetched *Lock value.
4359 OrderAccess::fence();
4360 for (;;) {
4361 w = *Lock ;
4362 if ((w & LOCKBIT) == 0) {
4363 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4364 Self->OnList = 0 ; // hygiene - allows stronger asserts
4365 return ;
4366 }
4367 continue ; // Interference -- *Lock changed -- Just retry
4368 }
4369 assert (w & LOCKBIT, "invariant") ;
4370 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4371 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4372 }
4373
4374 while (Self->OnList != 0) {
4375 Self->park() ;
4376 }
4377 }
4378 }
4379
4380 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4381 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4382 if (w == 0) return ;
4383 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4384 return ;
4385 }
4386
4387 TEVENT (muxAcquire - Contention) ;
4388 ParkEvent * ReleaseAfter = NULL ;
4389 if (ev == NULL) {
4390 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4391 }
4392 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4393 for (;;) {
4394 guarantee (ev->OnList == 0, "invariant") ;
4395 int its = (os::is_MP() ? 100 : 0) + 1 ;
4396
4397 // Optional spin phase: spin-then-park strategy
4398 while (--its >= 0) {
4399 w = *Lock ;
4400 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4401 if (ReleaseAfter != NULL) {
4402 ParkEvent::Release (ReleaseAfter) ;
4403 }
4404 return ;
4405 }
4406 }
4407
4408 ev->reset() ;
4409 ev->OnList = intptr_t(Lock) ;
4410 // The following fence() isn't _strictly necessary as the subsequent
4411 // CAS() both serializes execution and ratifies the fetched *Lock value.
4412 OrderAccess::fence();
4413 for (;;) {
4414 w = *Lock ;
4415 if ((w & LOCKBIT) == 0) {
4416 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4417 ev->OnList = 0 ;
4418 // We call ::Release while holding the outer lock, thus
4419 // artificially lengthening the critical section.
4420 // Consider deferring the ::Release() until the subsequent unlock(),
4421 // after we've dropped the outer lock.
4422 if (ReleaseAfter != NULL) {
4423 ParkEvent::Release (ReleaseAfter) ;
4424 }
4425 return ;
4426 }
4427 continue ; // Interference -- *Lock changed -- Just retry
4428 }
4429 assert (w & LOCKBIT, "invariant") ;
4430 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4431 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4432 }
4433
4434 while (ev->OnList != 0) {
4435 ev->park() ;
4436 }
4437 }
4438 }
4439
4440 // Release() must extract a successor from the list and then wake that thread.
4441 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4442 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4443 // Release() would :
4444 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4445 // (B) Extract a successor from the private list "in-hand"
4446 // (C) attempt to CAS() the residual back into *Lock over null.
4447 // If there were any newly arrived threads and the CAS() would fail.
4448 // In that case Release() would detach the RATs, re-merge the list in-hand
4449 // with the RATs and repeat as needed. Alternately, Release() might
4450 // detach and extract a successor, but then pass the residual list to the wakee.
4451 // The wakee would be responsible for reattaching and remerging before it
4452 // competed for the lock.
4453 //
4454 // Both "pop" and DMR are immune from ABA corruption -- there can be
4455 // multiple concurrent pushers, but only one popper or detacher.
4456 // This implementation pops from the head of the list. This is unfair,
4457 // but tends to provide excellent throughput as hot threads remain hot.
4458 // (We wake recently run threads first).
4459
4460 void Thread::muxRelease (volatile intptr_t * Lock) {
4461 for (;;) {
4462 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4463 assert (w & LOCKBIT, "invariant") ;
4464 if (w == LOCKBIT) return ;
4465 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4466 assert (List != NULL, "invariant") ;
4467 assert (List->OnList == intptr_t(Lock), "invariant") ;
4468 ParkEvent * nxt = List->ListNext ;
4469
4470 // The following CAS() releases the lock and pops the head element.
4471 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4472 continue ;
4473 }
4474 List->OnList = 0 ;
4475 OrderAccess::fence() ;
4476 List->unpark () ;
4477 return ;
4478 }
4479 }
4480
4481
4482 void Threads::verify() {
4483 ALL_JAVA_THREADS(p) {
4484 p->verify();
4485 }
4486 VMThread* thread = VMThread::vm_thread();
4487 if (thread != NULL) thread->verify();
4488 }