1 /*
2 * Copyright (c) 1997, 2015, 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/codeCache.hpp"
31 #include "code/scopeDesc.hpp"
32 #include "compiler/compileBroker.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "interpreter/linkResolver.hpp"
35 #include "interpreter/oopMapCache.hpp"
36 #include "jvmtifiles/jvmtiEnv.hpp"
37 #include "memory/gcLocker.inline.hpp"
38 #include "memory/metaspaceShared.hpp"
39 #include "memory/oopFactory.hpp"
40 #include "memory/universe.inline.hpp"
41 #include "oops/instanceKlass.hpp"
42 #include "oops/objArrayOop.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "oops/symbol.hpp"
45 #include "prims/jvm_misc.hpp"
46 #include "prims/jvmtiExport.hpp"
47 #include "prims/jvmtiThreadState.hpp"
48 #include "prims/privilegedStack.hpp"
49 #include "runtime/arguments.hpp"
50 #include "runtime/atomic.inline.hpp"
51 #include "runtime/biasedLocking.hpp"
52 #include "runtime/deoptimization.hpp"
53 #include "runtime/fprofiler.hpp"
54 #include "runtime/frame.inline.hpp"
55 #include "runtime/init.hpp"
56 #include "runtime/interfaceSupport.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/javaCalls.hpp"
59 #include "runtime/jniPeriodicChecker.hpp"
60 #include "runtime/memprofiler.hpp"
61 #include "runtime/mutexLocker.hpp"
62 #include "runtime/objectMonitor.hpp"
63 #include "runtime/orderAccess.inline.hpp"
64 #include "runtime/osThread.hpp"
65 #include "runtime/safepoint.hpp"
66 #include "runtime/sharedRuntime.hpp"
67 #include "runtime/statSampler.hpp"
68 #include "runtime/stubRoutines.hpp"
69 #include "runtime/sweeper.hpp"
70 #include "runtime/task.hpp"
71 #include "runtime/thread.inline.hpp"
72 #include "runtime/threadCritical.hpp"
73 #include "runtime/threadLocalStorage.hpp"
74 #include "runtime/vframe.hpp"
75 #include "runtime/vframeArray.hpp"
76 #include "runtime/vframe_hp.hpp"
77 #include "runtime/vmThread.hpp"
78 #include "runtime/vm_operations.hpp"
79 #include "runtime/vm_version.hpp"
80 #include "services/attachListener.hpp"
81 #include "services/management.hpp"
82 #include "services/memTracker.hpp"
83 #include "services/threadService.hpp"
84 #include "trace/tracing.hpp"
85 #include "trace/traceMacros.hpp"
86 #include "utilities/defaultStream.hpp"
87 #include "utilities/dtrace.hpp"
88 #include "utilities/events.hpp"
89 #include "utilities/preserveException.hpp"
90 #include "utilities/macros.hpp"
91 #if INCLUDE_ALL_GCS
92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
95 #endif // INCLUDE_ALL_GCS
96 #ifdef COMPILER1
97 #include "c1/c1_Compiler.hpp"
98 #endif
99 #ifdef COMPILER2
100 #include "opto/c2compiler.hpp"
101 #include "opto/idealGraphPrinter.hpp"
102 #endif
103 #if INCLUDE_RTM_OPT
104 #include "runtime/rtmLocking.hpp"
105 #endif
106
107 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
108
109 #ifdef DTRACE_ENABLED
110
111 // Only bother with this argument setup if dtrace is available
112
113 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
114 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
115
116 #define DTRACE_THREAD_PROBE(probe, javathread) \
117 { \
118 ResourceMark rm(this); \
119 int len = 0; \
120 const char* name = (javathread)->get_thread_name(); \
121 len = strlen(name); \
122 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
123 (char *) name, len, \
124 java_lang_Thread::thread_id((javathread)->threadObj()), \
125 (uintptr_t) (javathread)->osthread()->thread_id(), \
126 java_lang_Thread::is_daemon((javathread)->threadObj())); \
127 }
128
129 #else // ndef DTRACE_ENABLED
130
131 #define DTRACE_THREAD_PROBE(probe, javathread)
132
133 #endif // ndef DTRACE_ENABLED
134
135
136 // Class hierarchy
137 // - Thread
138 // - VMThread
139 // - WatcherThread
140 // - ConcurrentMarkSweepThread
141 // - JavaThread
142 // - CompilerThread
143
144 // ======= Thread ========
145 // Support for forcing alignment of thread objects for biased locking
146 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
147 if (UseBiasedLocking) {
148 const int alignment = markOopDesc::biased_lock_alignment;
149 size_t aligned_size = size + (alignment - sizeof(intptr_t));
150 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
151 : AllocateHeap(aligned_size, flags, CURRENT_PC,
152 AllocFailStrategy::RETURN_NULL);
153 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
154 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
155 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
156 "JavaThread alignment code overflowed allocated storage");
157 if (TraceBiasedLocking) {
158 if (aligned_addr != real_malloc_addr) {
159 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
160 real_malloc_addr, aligned_addr);
161 }
162 }
163 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
164 return aligned_addr;
165 } else {
166 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
167 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
168 }
169 }
170
171 void Thread::operator delete(void* p) {
172 if (UseBiasedLocking) {
173 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
174 FreeHeap(real_malloc_addr);
175 } else {
176 FreeHeap(p);
177 }
178 }
179
180
181 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
182 // JavaThread
183
184
185 Thread::Thread() {
186 // stack and get_thread
187 set_stack_base(NULL);
188 set_stack_size(0);
189 set_self_raw_id(0);
190 set_lgrp_id(-1);
191
192 // allocated data structures
193 set_osthread(NULL);
194 set_resource_area(new (mtThread)ResourceArea());
195 DEBUG_ONLY(_current_resource_mark = NULL;)
196 set_handle_area(new (mtThread) HandleArea(NULL));
197 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
198 set_active_handles(NULL);
199 set_free_handle_block(NULL);
200 set_last_handle_mark(NULL);
201
202 // This initial value ==> never claimed.
203 _oops_do_parity = 0;
204
205 _metadata_on_stack_buffer = NULL;
206
207 // the handle mark links itself to last_handle_mark
208 new HandleMark(this);
209
210 // plain initialization
211 debug_only(_owned_locks = NULL;)
212 debug_only(_allow_allocation_count = 0;)
213 NOT_PRODUCT(_allow_safepoint_count = 0;)
214 NOT_PRODUCT(_skip_gcalot = false;)
215 _jvmti_env_iteration_count = 0;
216 set_allocated_bytes(0);
217 _vm_operation_started_count = 0;
218 _vm_operation_completed_count = 0;
219 _current_pending_monitor = NULL;
220 _current_pending_monitor_is_from_java = true;
221 _current_waiting_monitor = NULL;
222 _num_nested_signal = 0;
223 omFreeList = NULL;
224 omFreeCount = 0;
225 omFreeProvision = 32;
226 omInUseList = NULL;
227 omInUseCount = 0;
228
229 #ifdef ASSERT
230 _visited_for_critical_count = false;
231 #endif
232
233 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
234 Monitor::_safepoint_check_sometimes);
235 _suspend_flags = 0;
236
237 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
238 _hashStateX = os::random();
239 _hashStateY = 842502087;
240 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
241 _hashStateW = 273326509;
242
243 _OnTrap = 0;
244 _schedctl = NULL;
245 _Stalled = 0;
246 _TypeTag = 0x2BAD;
247
248 // Many of the following fields are effectively final - immutable
249 // Note that nascent threads can't use the Native Monitor-Mutex
250 // construct until the _MutexEvent is initialized ...
251 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
252 // we might instead use a stack of ParkEvents that we could provision on-demand.
253 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
254 // and ::Release()
255 _ParkEvent = ParkEvent::Allocate(this);
256 _SleepEvent = ParkEvent::Allocate(this);
257 _MutexEvent = ParkEvent::Allocate(this);
258 _MuxEvent = ParkEvent::Allocate(this);
259
260 #ifdef CHECK_UNHANDLED_OOPS
261 if (CheckUnhandledOops) {
262 _unhandled_oops = new UnhandledOops(this);
263 }
264 #endif // CHECK_UNHANDLED_OOPS
265 #ifdef ASSERT
266 if (UseBiasedLocking) {
267 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
268 assert(this == _real_malloc_address ||
269 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
270 "bug in forced alignment of thread objects");
271 }
272 #endif // ASSERT
273 }
274
275 void Thread::initialize_thread_local_storage() {
276 // Note: Make sure this method only calls
277 // non-blocking operations. Otherwise, it might not work
278 // with the thread-startup/safepoint interaction.
279
280 // During Java thread startup, safepoint code should allow this
281 // method to complete because it may need to allocate memory to
282 // store information for the new thread.
283
284 // initialize structure dependent on thread local storage
285 ThreadLocalStorage::set_thread(this);
286 }
287
288 void Thread::record_stack_base_and_size() {
289 set_stack_base(os::current_stack_base());
290 set_stack_size(os::current_stack_size());
291 if (is_Java_thread()) {
292 ((JavaThread*) this)->set_stack_overflow_limit();
293 }
294 // CR 7190089: on Solaris, primordial thread's stack is adjusted
295 // in initialize_thread(). Without the adjustment, stack size is
296 // incorrect if stack is set to unlimited (ulimit -s unlimited).
297 // So far, only Solaris has real implementation of initialize_thread().
298 //
299 // set up any platform-specific state.
300 os::initialize_thread(this);
301
302 #if INCLUDE_NMT
303 // record thread's native stack, stack grows downward
304 address stack_low_addr = stack_base() - stack_size();
305 MemTracker::record_thread_stack(stack_low_addr, stack_size());
306 #endif // INCLUDE_NMT
307 }
308
309
310 Thread::~Thread() {
311 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
312 ObjectSynchronizer::omFlush(this);
313
314 EVENT_THREAD_DESTRUCT(this);
315
316 // stack_base can be NULL if the thread is never started or exited before
317 // record_stack_base_and_size called. Although, we would like to ensure
318 // that all started threads do call record_stack_base_and_size(), there is
319 // not proper way to enforce that.
320 #if INCLUDE_NMT
321 if (_stack_base != NULL) {
322 address low_stack_addr = stack_base() - stack_size();
323 MemTracker::release_thread_stack(low_stack_addr, stack_size());
324 #ifdef ASSERT
325 set_stack_base(NULL);
326 #endif
327 }
328 #endif // INCLUDE_NMT
329
330 // deallocate data structures
331 delete resource_area();
332 // since the handle marks are using the handle area, we have to deallocated the root
333 // handle mark before deallocating the thread's handle area,
334 assert(last_handle_mark() != NULL, "check we have an element");
335 delete last_handle_mark();
336 assert(last_handle_mark() == NULL, "check we have reached the end");
337
338 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
339 // We NULL out the fields for good hygiene.
340 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
341 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
342 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
343 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
344
345 delete handle_area();
346 delete metadata_handles();
347
348 // osthread() can be NULL, if creation of thread failed.
349 if (osthread() != NULL) os::free_thread(osthread());
350
351 delete _SR_lock;
352
353 // clear thread local storage if the Thread is deleting itself
354 if (this == Thread::current()) {
355 ThreadLocalStorage::set_thread(NULL);
356 } else {
357 // In the case where we're not the current thread, invalidate all the
358 // caches in case some code tries to get the current thread or the
359 // thread that was destroyed, and gets stale information.
360 ThreadLocalStorage::invalidate_all();
361 }
362 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
363 }
364
365 // NOTE: dummy function for assertion purpose.
366 void Thread::run() {
367 ShouldNotReachHere();
368 }
369
370 #ifdef ASSERT
371 // Private method to check for dangling thread pointer
372 void check_for_dangling_thread_pointer(Thread *thread) {
373 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
374 "possibility of dangling Thread pointer");
375 }
376 #endif
377
378 ThreadPriority Thread::get_priority(const Thread* const thread) {
379 ThreadPriority priority;
380 // Can return an error!
381 (void)os::get_priority(thread, priority);
382 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
383 return priority;
384 }
385
386 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
387 debug_only(check_for_dangling_thread_pointer(thread);)
388 // Can return an error!
389 (void)os::set_priority(thread, priority);
390 }
391
392
393 void Thread::start(Thread* thread) {
394 // Start is different from resume in that its safety is guaranteed by context or
395 // being called from a Java method synchronized on the Thread object.
396 if (!DisableStartThread) {
397 if (thread->is_Java_thread()) {
398 // Initialize the thread state to RUNNABLE before starting this thread.
399 // Can not set it after the thread started because we do not know the
400 // exact thread state at that time. It could be in MONITOR_WAIT or
401 // in SLEEPING or some other state.
402 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
403 java_lang_Thread::RUNNABLE);
404 }
405 os::start_thread(thread);
406 }
407 }
408
409 // Enqueue a VM_Operation to do the job for us - sometime later
410 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
411 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
412 VMThread::execute(vm_stop);
413 }
414
415
416 // Check if an external suspend request has completed (or has been
417 // cancelled). Returns true if the thread is externally suspended and
418 // false otherwise.
419 //
420 // The bits parameter returns information about the code path through
421 // the routine. Useful for debugging:
422 //
423 // set in is_ext_suspend_completed():
424 // 0x00000001 - routine was entered
425 // 0x00000010 - routine return false at end
426 // 0x00000100 - thread exited (return false)
427 // 0x00000200 - suspend request cancelled (return false)
428 // 0x00000400 - thread suspended (return true)
429 // 0x00001000 - thread is in a suspend equivalent state (return true)
430 // 0x00002000 - thread is native and walkable (return true)
431 // 0x00004000 - thread is native_trans and walkable (needed retry)
432 //
433 // set in wait_for_ext_suspend_completion():
434 // 0x00010000 - routine was entered
435 // 0x00020000 - suspend request cancelled before loop (return false)
436 // 0x00040000 - thread suspended before loop (return true)
437 // 0x00080000 - suspend request cancelled in loop (return false)
438 // 0x00100000 - thread suspended in loop (return true)
439 // 0x00200000 - suspend not completed during retry loop (return false)
440
441 // Helper class for tracing suspend wait debug bits.
442 //
443 // 0x00000100 indicates that the target thread exited before it could
444 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
445 // 0x00080000 each indicate a cancelled suspend request so they don't
446 // count as wait failures either.
447 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
448
449 class TraceSuspendDebugBits : public StackObj {
450 private:
451 JavaThread * jt;
452 bool is_wait;
453 bool called_by_wait; // meaningful when !is_wait
454 uint32_t * bits;
455
456 public:
457 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
458 uint32_t *_bits) {
459 jt = _jt;
460 is_wait = _is_wait;
461 called_by_wait = _called_by_wait;
462 bits = _bits;
463 }
464
465 ~TraceSuspendDebugBits() {
466 if (!is_wait) {
467 #if 1
468 // By default, don't trace bits for is_ext_suspend_completed() calls.
469 // That trace is very chatty.
470 return;
471 #else
472 if (!called_by_wait) {
473 // If tracing for is_ext_suspend_completed() is enabled, then only
474 // trace calls to it from wait_for_ext_suspend_completion()
475 return;
476 }
477 #endif
478 }
479
480 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
481 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
482 MutexLocker ml(Threads_lock); // needed for get_thread_name()
483 ResourceMark rm;
484
485 tty->print_cr(
486 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
487 jt->get_thread_name(), *bits);
488
489 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
490 }
491 }
492 }
493 };
494 #undef DEBUG_FALSE_BITS
495
496
497 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
498 uint32_t *bits) {
499 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
500
501 bool did_trans_retry = false; // only do thread_in_native_trans retry once
502 bool do_trans_retry; // flag to force the retry
503
504 *bits |= 0x00000001;
505
506 do {
507 do_trans_retry = false;
508
509 if (is_exiting()) {
510 // Thread is in the process of exiting. This is always checked
511 // first to reduce the risk of dereferencing a freed JavaThread.
512 *bits |= 0x00000100;
513 return false;
514 }
515
516 if (!is_external_suspend()) {
517 // Suspend request is cancelled. This is always checked before
518 // is_ext_suspended() to reduce the risk of a rogue resume
519 // confusing the thread that made the suspend request.
520 *bits |= 0x00000200;
521 return false;
522 }
523
524 if (is_ext_suspended()) {
525 // thread is suspended
526 *bits |= 0x00000400;
527 return true;
528 }
529
530 // Now that we no longer do hard suspends of threads running
531 // native code, the target thread can be changing thread state
532 // while we are in this routine:
533 //
534 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
535 //
536 // We save a copy of the thread state as observed at this moment
537 // and make our decision about suspend completeness based on the
538 // copy. This closes the race where the thread state is seen as
539 // _thread_in_native_trans in the if-thread_blocked check, but is
540 // seen as _thread_blocked in if-thread_in_native_trans check.
541 JavaThreadState save_state = thread_state();
542
543 if (save_state == _thread_blocked && is_suspend_equivalent()) {
544 // If the thread's state is _thread_blocked and this blocking
545 // condition is known to be equivalent to a suspend, then we can
546 // consider the thread to be externally suspended. This means that
547 // the code that sets _thread_blocked has been modified to do
548 // self-suspension if the blocking condition releases. We also
549 // used to check for CONDVAR_WAIT here, but that is now covered by
550 // the _thread_blocked with self-suspension check.
551 //
552 // Return true since we wouldn't be here unless there was still an
553 // external suspend request.
554 *bits |= 0x00001000;
555 return true;
556 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
557 // Threads running native code will self-suspend on native==>VM/Java
558 // transitions. If its stack is walkable (should always be the case
559 // unless this function is called before the actual java_suspend()
560 // call), then the wait is done.
561 *bits |= 0x00002000;
562 return true;
563 } else if (!called_by_wait && !did_trans_retry &&
564 save_state == _thread_in_native_trans &&
565 frame_anchor()->walkable()) {
566 // The thread is transitioning from thread_in_native to another
567 // thread state. check_safepoint_and_suspend_for_native_trans()
568 // will force the thread to self-suspend. If it hasn't gotten
569 // there yet we may have caught the thread in-between the native
570 // code check above and the self-suspend. Lucky us. If we were
571 // called by wait_for_ext_suspend_completion(), then it
572 // will be doing the retries so we don't have to.
573 //
574 // Since we use the saved thread state in the if-statement above,
575 // there is a chance that the thread has already transitioned to
576 // _thread_blocked by the time we get here. In that case, we will
577 // make a single unnecessary pass through the logic below. This
578 // doesn't hurt anything since we still do the trans retry.
579
580 *bits |= 0x00004000;
581
582 // Once the thread leaves thread_in_native_trans for another
583 // thread state, we break out of this retry loop. We shouldn't
584 // need this flag to prevent us from getting back here, but
585 // sometimes paranoia is good.
586 did_trans_retry = true;
587
588 // We wait for the thread to transition to a more usable state.
589 for (int i = 1; i <= SuspendRetryCount; i++) {
590 // We used to do an "os::yield_all(i)" call here with the intention
591 // that yielding would increase on each retry. However, the parameter
592 // is ignored on Linux which means the yield didn't scale up. Waiting
593 // on the SR_lock below provides a much more predictable scale up for
594 // the delay. It also provides a simple/direct point to check for any
595 // safepoint requests from the VMThread
596
597 // temporarily drops SR_lock while doing wait with safepoint check
598 // (if we're a JavaThread - the WatcherThread can also call this)
599 // and increase delay with each retry
600 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
601
602 // check the actual thread state instead of what we saved above
603 if (thread_state() != _thread_in_native_trans) {
604 // the thread has transitioned to another thread state so
605 // try all the checks (except this one) one more time.
606 do_trans_retry = true;
607 break;
608 }
609 } // end retry loop
610
611
612 }
613 } while (do_trans_retry);
614
615 *bits |= 0x00000010;
616 return false;
617 }
618
619 // Wait for an external suspend request to complete (or be cancelled).
620 // Returns true if the thread is externally suspended and false otherwise.
621 //
622 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
623 uint32_t *bits) {
624 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
625 false /* !called_by_wait */, bits);
626
627 // local flag copies to minimize SR_lock hold time
628 bool is_suspended;
629 bool pending;
630 uint32_t reset_bits;
631
632 // set a marker so is_ext_suspend_completed() knows we are the caller
633 *bits |= 0x00010000;
634
635 // We use reset_bits to reinitialize the bits value at the top of
636 // each retry loop. This allows the caller to make use of any
637 // unused bits for their own marking purposes.
638 reset_bits = *bits;
639
640 {
641 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
642 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
643 delay, bits);
644 pending = is_external_suspend();
645 }
646 // must release SR_lock to allow suspension to complete
647
648 if (!pending) {
649 // A cancelled suspend request is the only false return from
650 // is_ext_suspend_completed() that keeps us from entering the
651 // retry loop.
652 *bits |= 0x00020000;
653 return false;
654 }
655
656 if (is_suspended) {
657 *bits |= 0x00040000;
658 return true;
659 }
660
661 for (int i = 1; i <= retries; i++) {
662 *bits = reset_bits; // reinit to only track last retry
663
664 // We used to do an "os::yield_all(i)" call here with the intention
665 // that yielding would increase on each retry. However, the parameter
666 // is ignored on Linux which means the yield didn't scale up. Waiting
667 // on the SR_lock below provides a much more predictable scale up for
668 // the delay. It also provides a simple/direct point to check for any
669 // safepoint requests from the VMThread
670
671 {
672 MutexLocker ml(SR_lock());
673 // wait with safepoint check (if we're a JavaThread - the WatcherThread
674 // can also call this) and increase delay with each retry
675 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
676
677 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
678 delay, bits);
679
680 // It is possible for the external suspend request to be cancelled
681 // (by a resume) before the actual suspend operation is completed.
682 // Refresh our local copy to see if we still need to wait.
683 pending = is_external_suspend();
684 }
685
686 if (!pending) {
687 // A cancelled suspend request is the only false return from
688 // is_ext_suspend_completed() that keeps us from staying in the
689 // retry loop.
690 *bits |= 0x00080000;
691 return false;
692 }
693
694 if (is_suspended) {
695 *bits |= 0x00100000;
696 return true;
697 }
698 } // end retry loop
699
700 // thread did not suspend after all our retries
701 *bits |= 0x00200000;
702 return false;
703 }
704
705 #ifndef PRODUCT
706 void JavaThread::record_jump(address target, address instr, const char* file,
707 int line) {
708
709 // This should not need to be atomic as the only way for simultaneous
710 // updates is via interrupts. Even then this should be rare or non-existent
711 // and we don't care that much anyway.
712
713 int index = _jmp_ring_index;
714 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
715 _jmp_ring[index]._target = (intptr_t) target;
716 _jmp_ring[index]._instruction = (intptr_t) instr;
717 _jmp_ring[index]._file = file;
718 _jmp_ring[index]._line = line;
719 }
720 #endif // PRODUCT
721
722 // Called by flat profiler
723 // Callers have already called wait_for_ext_suspend_completion
724 // The assertion for that is currently too complex to put here:
725 bool JavaThread::profile_last_Java_frame(frame* _fr) {
726 bool gotframe = false;
727 // self suspension saves needed state.
728 if (has_last_Java_frame() && _anchor.walkable()) {
729 *_fr = pd_last_frame();
730 gotframe = true;
731 }
732 return gotframe;
733 }
734
735 void Thread::interrupt(Thread* thread) {
736 debug_only(check_for_dangling_thread_pointer(thread);)
737 os::interrupt(thread);
738 }
739
740 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
741 debug_only(check_for_dangling_thread_pointer(thread);)
742 // Note: If clear_interrupted==false, this simply fetches and
743 // returns the value of the field osthread()->interrupted().
744 return os::is_interrupted(thread, clear_interrupted);
745 }
746
747
748 // GC Support
749 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
750 jint thread_parity = _oops_do_parity;
751 if (thread_parity != strong_roots_parity) {
752 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
753 if (res == thread_parity) {
754 return true;
755 } else {
756 guarantee(res == strong_roots_parity, "Or else what?");
757 assert(SharedHeap::heap()->workers()->active_workers() > 0,
758 "Should only fail when parallel.");
759 return false;
760 }
761 }
762 assert(SharedHeap::heap()->workers()->active_workers() > 0,
763 "Should only fail when parallel.");
764 return false;
765 }
766
767 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
768 active_handles()->oops_do(f);
769 // Do oop for ThreadShadow
770 f->do_oop((oop*)&_pending_exception);
771 handle_area()->oops_do(f);
772 }
773
774 void Thread::nmethods_do(CodeBlobClosure* cf) {
775 // no nmethods in a generic thread...
776 }
777
778 void Thread::metadata_do(void f(Metadata*)) {
779 if (metadata_handles() != NULL) {
780 for (int i = 0; i< metadata_handles()->length(); i++) {
781 f(metadata_handles()->at(i));
782 }
783 }
784 }
785
786 void Thread::print_on(outputStream* st) const {
787 // get_priority assumes osthread initialized
788 if (osthread() != NULL) {
789 int os_prio;
790 if (os::get_native_priority(this, &os_prio) == OS_OK) {
791 st->print("os_prio=%d ", os_prio);
792 }
793 st->print("tid=" INTPTR_FORMAT " ", this);
794 ext().print_on(st);
795 osthread()->print_on(st);
796 }
797 debug_only(if (WizardMode) print_owned_locks_on(st);)
798 }
799
800 // Thread::print_on_error() is called by fatal error handler. Don't use
801 // any lock or allocate memory.
802 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
803 if (is_VM_thread()) st->print("VMThread");
804 else if (is_Compiler_thread()) st->print("CompilerThread");
805 else if (is_Java_thread()) st->print("JavaThread");
806 else if (is_GC_task_thread()) st->print("GCTaskThread");
807 else if (is_Watcher_thread()) st->print("WatcherThread");
808 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
809 else st->print("Thread");
810
811 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
812 _stack_base - _stack_size, _stack_base);
813
814 if (osthread()) {
815 st->print(" [id=%d]", osthread()->thread_id());
816 }
817 }
818
819 #ifdef ASSERT
820 void Thread::print_owned_locks_on(outputStream* st) const {
821 Monitor *cur = _owned_locks;
822 if (cur == NULL) {
823 st->print(" (no locks) ");
824 } else {
825 st->print_cr(" Locks owned:");
826 while (cur) {
827 cur->print_on(st);
828 cur = cur->next();
829 }
830 }
831 }
832
833 static int ref_use_count = 0;
834
835 bool Thread::owns_locks_but_compiled_lock() const {
836 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
837 if (cur != Compile_lock) return true;
838 }
839 return false;
840 }
841
842
843 #endif
844
845 #ifndef PRODUCT
846
847 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
848 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
849 // no threads which allow_vm_block's are held
850 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
851 // Check if current thread is allowed to block at a safepoint
852 if (!(_allow_safepoint_count == 0)) {
853 fatal("Possible safepoint reached by thread that does not allow it");
854 }
855 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
856 fatal("LEAF method calling lock?");
857 }
858
859 #ifdef ASSERT
860 if (potential_vm_operation && is_Java_thread()
861 && !Universe::is_bootstrapping()) {
862 // Make sure we do not hold any locks that the VM thread also uses.
863 // This could potentially lead to deadlocks
864 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
865 // Threads_lock is special, since the safepoint synchronization will not start before this is
866 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
867 // since it is used to transfer control between JavaThreads and the VMThread
868 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
869 if ((cur->allow_vm_block() &&
870 cur != Threads_lock &&
871 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
872 cur != VMOperationRequest_lock &&
873 cur != VMOperationQueue_lock) ||
874 cur->rank() == Mutex::special) {
875 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
876 }
877 }
878 }
879
880 if (GCALotAtAllSafepoints) {
881 // We could enter a safepoint here and thus have a gc
882 InterfaceSupport::check_gc_alot();
883 }
884 #endif
885 }
886 #endif
887
888 bool Thread::is_in_stack(address adr) const {
889 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
890 address end = os::current_stack_pointer();
891 // Allow non Java threads to call this without stack_base
892 if (_stack_base == NULL) return true;
893 if (stack_base() >= adr && adr >= end) return true;
894
895 return false;
896 }
897
898
899 bool Thread::is_in_usable_stack(address adr) const {
900 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
901 size_t usable_stack_size = _stack_size - stack_guard_size;
902
903 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
904 }
905
906
907 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
908 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
909 // used for compilation in the future. If that change is made, the need for these methods
910 // should be revisited, and they should be removed if possible.
911
912 bool Thread::is_lock_owned(address adr) const {
913 return on_local_stack(adr);
914 }
915
916 bool Thread::set_as_starting_thread() {
917 // NOTE: this must be called inside the main thread.
918 return os::create_main_thread((JavaThread*)this);
919 }
920
921 static void initialize_class(Symbol* class_name, TRAPS) {
922 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
923 InstanceKlass::cast(klass)->initialize(CHECK);
924 }
925
926
927 // Creates the initial ThreadGroup
928 static Handle create_initial_thread_group(TRAPS) {
929 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
930 instanceKlassHandle klass (THREAD, k);
931
932 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
933 {
934 JavaValue result(T_VOID);
935 JavaCalls::call_special(&result,
936 system_instance,
937 klass,
938 vmSymbols::object_initializer_name(),
939 vmSymbols::void_method_signature(),
940 CHECK_NH);
941 }
942 Universe::set_system_thread_group(system_instance());
943
944 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
945 {
946 JavaValue result(T_VOID);
947 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
948 JavaCalls::call_special(&result,
949 main_instance,
950 klass,
951 vmSymbols::object_initializer_name(),
952 vmSymbols::threadgroup_string_void_signature(),
953 system_instance,
954 string,
955 CHECK_NH);
956 }
957 return main_instance;
958 }
959
960 // Creates the initial Thread
961 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
962 TRAPS) {
963 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
964 instanceKlassHandle klass (THREAD, k);
965 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
966
967 java_lang_Thread::set_thread(thread_oop(), thread);
968 java_lang_Thread::set_priority(thread_oop(), NormPriority);
969 thread->set_threadObj(thread_oop());
970
971 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
972
973 JavaValue result(T_VOID);
974 JavaCalls::call_special(&result, thread_oop,
975 klass,
976 vmSymbols::object_initializer_name(),
977 vmSymbols::threadgroup_string_void_signature(),
978 thread_group,
979 string,
980 CHECK_NULL);
981 return thread_oop();
982 }
983
984 static void call_initializeSystemClass(TRAPS) {
985 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
986 instanceKlassHandle klass (THREAD, k);
987
988 JavaValue result(T_VOID);
989 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
990 vmSymbols::void_method_signature(), CHECK);
991 }
992
993 char java_runtime_name[128] = "";
994 char java_runtime_version[128] = "";
995
996 // extract the JRE name from sun.misc.Version.java_runtime_name
997 static const char* get_java_runtime_name(TRAPS) {
998 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
999 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1000 fieldDescriptor fd;
1001 bool found = k != NULL &&
1002 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1003 vmSymbols::string_signature(), &fd);
1004 if (found) {
1005 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1006 if (name_oop == NULL) {
1007 return NULL;
1008 }
1009 const char* name = java_lang_String::as_utf8_string(name_oop,
1010 java_runtime_name,
1011 sizeof(java_runtime_name));
1012 return name;
1013 } else {
1014 return NULL;
1015 }
1016 }
1017
1018 // extract the JRE version from sun.misc.Version.java_runtime_version
1019 static const char* get_java_runtime_version(TRAPS) {
1020 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1021 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1022 fieldDescriptor fd;
1023 bool found = k != NULL &&
1024 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1025 vmSymbols::string_signature(), &fd);
1026 if (found) {
1027 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1028 if (name_oop == NULL) {
1029 return NULL;
1030 }
1031 const char* name = java_lang_String::as_utf8_string(name_oop,
1032 java_runtime_version,
1033 sizeof(java_runtime_version));
1034 return name;
1035 } else {
1036 return NULL;
1037 }
1038 }
1039
1040 // General purpose hook into Java code, run once when the VM is initialized.
1041 // The Java library method itself may be changed independently from the VM.
1042 static void call_postVMInitHook(TRAPS) {
1043 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1044 instanceKlassHandle klass (THREAD, k);
1045 if (klass.not_null()) {
1046 JavaValue result(T_VOID);
1047 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1048 vmSymbols::void_method_signature(),
1049 CHECK);
1050 }
1051 }
1052
1053 static void reset_vm_info_property(TRAPS) {
1054 // the vm info string
1055 ResourceMark rm(THREAD);
1056 const char *vm_info = VM_Version::vm_info_string();
1057
1058 // java.lang.System class
1059 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1060 instanceKlassHandle klass (THREAD, k);
1061
1062 // setProperty arguments
1063 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1064 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1065
1066 // return value
1067 JavaValue r(T_OBJECT);
1068
1069 // public static String setProperty(String key, String value);
1070 JavaCalls::call_static(&r,
1071 klass,
1072 vmSymbols::setProperty_name(),
1073 vmSymbols::string_string_string_signature(),
1074 key_str,
1075 value_str,
1076 CHECK);
1077 }
1078
1079
1080 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1081 bool daemon, TRAPS) {
1082 assert(thread_group.not_null(), "thread group should be specified");
1083 assert(threadObj() == NULL, "should only create Java thread object once");
1084
1085 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1086 instanceKlassHandle klass (THREAD, k);
1087 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1088
1089 java_lang_Thread::set_thread(thread_oop(), this);
1090 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1091 set_threadObj(thread_oop());
1092
1093 JavaValue result(T_VOID);
1094 if (thread_name != NULL) {
1095 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1096 // Thread gets assigned specified name and null target
1097 JavaCalls::call_special(&result,
1098 thread_oop,
1099 klass,
1100 vmSymbols::object_initializer_name(),
1101 vmSymbols::threadgroup_string_void_signature(),
1102 thread_group, // Argument 1
1103 name, // Argument 2
1104 THREAD);
1105 } else {
1106 // Thread gets assigned name "Thread-nnn" and null target
1107 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1108 JavaCalls::call_special(&result,
1109 thread_oop,
1110 klass,
1111 vmSymbols::object_initializer_name(),
1112 vmSymbols::threadgroup_runnable_void_signature(),
1113 thread_group, // Argument 1
1114 Handle(), // Argument 2
1115 THREAD);
1116 }
1117
1118
1119 if (daemon) {
1120 java_lang_Thread::set_daemon(thread_oop());
1121 }
1122
1123 if (HAS_PENDING_EXCEPTION) {
1124 return;
1125 }
1126
1127 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1128 Handle threadObj(THREAD, this->threadObj());
1129
1130 JavaCalls::call_special(&result,
1131 thread_group,
1132 group,
1133 vmSymbols::add_method_name(),
1134 vmSymbols::thread_void_signature(),
1135 threadObj, // Arg 1
1136 THREAD);
1137 }
1138
1139 // NamedThread -- non-JavaThread subclasses with multiple
1140 // uniquely named instances should derive from this.
1141 NamedThread::NamedThread() : Thread() {
1142 _name = NULL;
1143 _processed_thread = NULL;
1144 }
1145
1146 NamedThread::~NamedThread() {
1147 if (_name != NULL) {
1148 FREE_C_HEAP_ARRAY(char, _name);
1149 _name = NULL;
1150 }
1151 }
1152
1153 void NamedThread::set_name(const char* format, ...) {
1154 guarantee(_name == NULL, "Only get to set name once.");
1155 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1156 guarantee(_name != NULL, "alloc failure");
1157 va_list ap;
1158 va_start(ap, format);
1159 jio_vsnprintf(_name, max_name_len, format, ap);
1160 va_end(ap);
1161 }
1162
1163 void NamedThread::print_on(outputStream* st) const {
1164 st->print("\"%s\" ", name());
1165 Thread::print_on(st);
1166 st->cr();
1167 }
1168
1169
1170 // ======= WatcherThread ========
1171
1172 // The watcher thread exists to simulate timer interrupts. It should
1173 // be replaced by an abstraction over whatever native support for
1174 // timer interrupts exists on the platform.
1175
1176 WatcherThread* WatcherThread::_watcher_thread = NULL;
1177 bool WatcherThread::_startable = false;
1178 volatile bool WatcherThread::_should_terminate = false;
1179
1180 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1181 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1182 if (os::create_thread(this, os::watcher_thread)) {
1183 _watcher_thread = this;
1184
1185 // Set the watcher thread to the highest OS priority which should not be
1186 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1187 // is created. The only normal thread using this priority is the reference
1188 // handler thread, which runs for very short intervals only.
1189 // If the VMThread's priority is not lower than the WatcherThread profiling
1190 // will be inaccurate.
1191 os::set_priority(this, MaxPriority);
1192 if (!DisableStartThread) {
1193 os::start_thread(this);
1194 }
1195 }
1196 }
1197
1198 int WatcherThread::sleep() const {
1199 // The WatcherThread does not honor the safepoint protocol for
1200 // PeriodicTask_lock in order to provide more consistent task
1201 // execution timing.
1202 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1203
1204 if (_should_terminate) {
1205 // check for termination before we do any housekeeping or wait
1206 return 0; // we did not sleep.
1207 }
1208
1209 // remaining will be zero if there are no tasks,
1210 // causing the WatcherThread to sleep until a task is
1211 // enrolled
1212 int remaining = PeriodicTask::time_to_wait();
1213 int time_slept = 0;
1214
1215 // we expect this to timeout - we only ever get unparked when
1216 // we should terminate or when a new task has been enrolled
1217 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1218
1219 jlong time_before_loop = os::javaTimeNanos();
1220
1221 while (true) {
1222 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1223 remaining);
1224 jlong now = os::javaTimeNanos();
1225
1226 if (remaining == 0) {
1227 // if we didn't have any tasks we could have waited for a long time
1228 // consider the time_slept zero and reset time_before_loop
1229 time_slept = 0;
1230 time_before_loop = now;
1231 } else {
1232 // need to recalculate since we might have new tasks in _tasks
1233 time_slept = (int) ((now - time_before_loop) / 1000000);
1234 }
1235
1236 // Change to task list or spurious wakeup of some kind
1237 if (timedout || _should_terminate) {
1238 break;
1239 }
1240
1241 remaining = PeriodicTask::time_to_wait();
1242 if (remaining == 0) {
1243 // Last task was just disenrolled so loop around and wait until
1244 // another task gets enrolled
1245 continue;
1246 }
1247
1248 remaining -= time_slept;
1249 if (remaining <= 0) {
1250 break;
1251 }
1252 }
1253
1254 return time_slept;
1255 }
1256
1257 void WatcherThread::run() {
1258 assert(this == watcher_thread(), "just checking");
1259
1260 this->record_stack_base_and_size();
1261 this->initialize_thread_local_storage();
1262 this->set_native_thread_name(this->name());
1263 this->set_active_handles(JNIHandleBlock::allocate_block());
1264 while (true) {
1265 assert(watcher_thread() == Thread::current(), "thread consistency check");
1266 assert(watcher_thread() == this, "thread consistency check");
1267
1268 // Calculate how long it'll be until the next PeriodicTask work
1269 // should be done, and sleep that amount of time.
1270 int time_waited = sleep();
1271
1272 if (is_error_reported()) {
1273 // A fatal error has happened, the error handler(VMError::report_and_die)
1274 // should abort JVM after creating an error log file. However in some
1275 // rare cases, the error handler itself might deadlock. Here we try to
1276 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1277 //
1278 // This code is in WatcherThread because WatcherThread wakes up
1279 // periodically so the fatal error handler doesn't need to do anything;
1280 // also because the WatcherThread is less likely to crash than other
1281 // threads.
1282
1283 for (;;) {
1284 if (!ShowMessageBoxOnError
1285 && (OnError == NULL || OnError[0] == '\0')
1286 && Arguments::abort_hook() == NULL) {
1287 os::sleep(this, 2 * 60 * 1000, false);
1288 fdStream err(defaultStream::output_fd());
1289 err.print_raw_cr("# [ timer expired, abort... ]");
1290 // skip atexit/vm_exit/vm_abort hooks
1291 os::die();
1292 }
1293
1294 // Wake up 5 seconds later, the fatal handler may reset OnError or
1295 // ShowMessageBoxOnError when it is ready to abort.
1296 os::sleep(this, 5 * 1000, false);
1297 }
1298 }
1299
1300 if (_should_terminate) {
1301 // check for termination before posting the next tick
1302 break;
1303 }
1304
1305 PeriodicTask::real_time_tick(time_waited);
1306 }
1307
1308 // Signal that it is terminated
1309 {
1310 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1311 _watcher_thread = NULL;
1312 Terminator_lock->notify();
1313 }
1314
1315 // Thread destructor usually does this..
1316 ThreadLocalStorage::set_thread(NULL);
1317 }
1318
1319 void WatcherThread::start() {
1320 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1321
1322 if (watcher_thread() == NULL && _startable) {
1323 _should_terminate = false;
1324 // Create the single instance of WatcherThread
1325 new WatcherThread();
1326 }
1327 }
1328
1329 void WatcherThread::make_startable() {
1330 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1331 _startable = true;
1332 }
1333
1334 void WatcherThread::stop() {
1335 {
1336 // Follow normal safepoint aware lock enter protocol since the
1337 // WatcherThread is stopped by another JavaThread.
1338 MutexLocker ml(PeriodicTask_lock);
1339 _should_terminate = true;
1340 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1341
1342 WatcherThread* watcher = watcher_thread();
1343 if (watcher != NULL) {
1344 // unpark the WatcherThread so it can see that it should terminate
1345 watcher->unpark();
1346 }
1347 }
1348
1349 MutexLocker mu(Terminator_lock);
1350
1351 while (watcher_thread() != NULL) {
1352 // This wait should make safepoint checks, wait without a timeout,
1353 // and wait as a suspend-equivalent condition.
1354 //
1355 // Note: If the FlatProfiler is running, then this thread is waiting
1356 // for the WatcherThread to terminate and the WatcherThread, via the
1357 // FlatProfiler task, is waiting for the external suspend request on
1358 // this thread to complete. wait_for_ext_suspend_completion() will
1359 // eventually timeout, but that takes time. Making this wait a
1360 // suspend-equivalent condition solves that timeout problem.
1361 //
1362 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1363 Mutex::_as_suspend_equivalent_flag);
1364 }
1365 }
1366
1367 void WatcherThread::unpark() {
1368 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1369 PeriodicTask_lock->notify();
1370 }
1371
1372 void WatcherThread::print_on(outputStream* st) const {
1373 st->print("\"%s\" ", name());
1374 Thread::print_on(st);
1375 st->cr();
1376 }
1377
1378 // ======= JavaThread ========
1379
1380 // A JavaThread is a normal Java thread
1381
1382 void JavaThread::initialize() {
1383 // Initialize fields
1384
1385 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1386 set_claimed_par_id(UINT_MAX);
1387
1388 set_saved_exception_pc(NULL);
1389 set_threadObj(NULL);
1390 _anchor.clear();
1391 set_entry_point(NULL);
1392 set_jni_functions(jni_functions());
1393 set_callee_target(NULL);
1394 set_vm_result(NULL);
1395 set_vm_result_2(NULL);
1396 set_vframe_array_head(NULL);
1397 set_vframe_array_last(NULL);
1398 set_deferred_locals(NULL);
1399 set_deopt_mark(NULL);
1400 set_deopt_nmethod(NULL);
1401 clear_must_deopt_id();
1402 set_monitor_chunks(NULL);
1403 set_next(NULL);
1404 set_thread_state(_thread_new);
1405 _terminated = _not_terminated;
1406 _privileged_stack_top = NULL;
1407 _array_for_gc = NULL;
1408 _suspend_equivalent = false;
1409 _in_deopt_handler = 0;
1410 _doing_unsafe_access = false;
1411 _stack_guard_state = stack_guard_unused;
1412 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1413 _exception_pc = 0;
1414 _exception_handler_pc = 0;
1415 _is_method_handle_return = 0;
1416 _jvmti_thread_state= NULL;
1417 _should_post_on_exceptions_flag = JNI_FALSE;
1418 _jvmti_get_loaded_classes_closure = NULL;
1419 _interp_only_mode = 0;
1420 _special_runtime_exit_condition = _no_async_condition;
1421 _pending_async_exception = NULL;
1422 _thread_stat = NULL;
1423 _thread_stat = new ThreadStatistics();
1424 _blocked_on_compilation = false;
1425 _jni_active_critical = 0;
1426 _pending_jni_exception_check_fn = NULL;
1427 _do_not_unlock_if_synchronized = false;
1428 _cached_monitor_info = NULL;
1429 _parker = Parker::Allocate(this);
1430
1431 #ifndef PRODUCT
1432 _jmp_ring_index = 0;
1433 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1434 record_jump(NULL, NULL, NULL, 0);
1435 }
1436 #endif // PRODUCT
1437
1438 set_thread_profiler(NULL);
1439 if (FlatProfiler::is_active()) {
1440 // This is where we would decide to either give each thread it's own profiler
1441 // or use one global one from FlatProfiler,
1442 // or up to some count of the number of profiled threads, etc.
1443 ThreadProfiler* pp = new ThreadProfiler();
1444 pp->engage();
1445 set_thread_profiler(pp);
1446 }
1447
1448 // Setup safepoint state info for this thread
1449 ThreadSafepointState::create(this);
1450
1451 debug_only(_java_call_counter = 0);
1452
1453 // JVMTI PopFrame support
1454 _popframe_condition = popframe_inactive;
1455 _popframe_preserved_args = NULL;
1456 _popframe_preserved_args_size = 0;
1457 _frames_to_pop_failed_realloc = 0;
1458
1459 pd_initialize();
1460 }
1461
1462 #if INCLUDE_ALL_GCS
1463 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1464 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1465 #endif // INCLUDE_ALL_GCS
1466
1467 JavaThread::JavaThread(bool is_attaching_via_jni) :
1468 Thread()
1469 #if INCLUDE_ALL_GCS
1470 , _satb_mark_queue(&_satb_mark_queue_set),
1471 _dirty_card_queue(&_dirty_card_queue_set)
1472 #endif // INCLUDE_ALL_GCS
1473 {
1474 initialize();
1475 if (is_attaching_via_jni) {
1476 _jni_attach_state = _attaching_via_jni;
1477 } else {
1478 _jni_attach_state = _not_attaching_via_jni;
1479 }
1480 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1481 }
1482
1483 bool JavaThread::reguard_stack(address cur_sp) {
1484 if (_stack_guard_state != stack_guard_yellow_disabled) {
1485 return true; // Stack already guarded or guard pages not needed.
1486 }
1487
1488 if (register_stack_overflow()) {
1489 // For those architectures which have separate register and
1490 // memory stacks, we must check the register stack to see if
1491 // it has overflowed.
1492 return false;
1493 }
1494
1495 // Java code never executes within the yellow zone: the latter is only
1496 // there to provoke an exception during stack banging. If java code
1497 // is executing there, either StackShadowPages should be larger, or
1498 // some exception code in c1, c2 or the interpreter isn't unwinding
1499 // when it should.
1500 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1501
1502 enable_stack_yellow_zone();
1503 return true;
1504 }
1505
1506 bool JavaThread::reguard_stack(void) {
1507 return reguard_stack(os::current_stack_pointer());
1508 }
1509
1510
1511 void JavaThread::block_if_vm_exited() {
1512 if (_terminated == _vm_exited) {
1513 // _vm_exited is set at safepoint, and Threads_lock is never released
1514 // we will block here forever
1515 Threads_lock->lock_without_safepoint_check();
1516 ShouldNotReachHere();
1517 }
1518 }
1519
1520
1521 // Remove this ifdef when C1 is ported to the compiler interface.
1522 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1523 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1524
1525 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1526 Thread()
1527 #if INCLUDE_ALL_GCS
1528 , _satb_mark_queue(&_satb_mark_queue_set),
1529 _dirty_card_queue(&_dirty_card_queue_set)
1530 #endif // INCLUDE_ALL_GCS
1531 {
1532 initialize();
1533 _jni_attach_state = _not_attaching_via_jni;
1534 set_entry_point(entry_point);
1535 // Create the native thread itself.
1536 // %note runtime_23
1537 os::ThreadType thr_type = os::java_thread;
1538 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1539 os::java_thread;
1540 os::create_thread(this, thr_type, stack_sz);
1541 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1542 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1543 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1544 // the exception consists of creating the exception object & initializing it, initialization
1545 // will leave the VM via a JavaCall and then all locks must be unlocked).
1546 //
1547 // The thread is still suspended when we reach here. Thread must be explicit started
1548 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1549 // by calling Threads:add. The reason why this is not done here, is because the thread
1550 // object must be fully initialized (take a look at JVM_Start)
1551 }
1552
1553 JavaThread::~JavaThread() {
1554
1555 // JSR166 -- return the parker to the free list
1556 Parker::Release(_parker);
1557 _parker = NULL;
1558
1559 // Free any remaining previous UnrollBlock
1560 vframeArray* old_array = vframe_array_last();
1561
1562 if (old_array != NULL) {
1563 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1564 old_array->set_unroll_block(NULL);
1565 delete old_info;
1566 delete old_array;
1567 }
1568
1569 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1570 if (deferred != NULL) {
1571 // This can only happen if thread is destroyed before deoptimization occurs.
1572 assert(deferred->length() != 0, "empty array!");
1573 do {
1574 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1575 deferred->remove_at(0);
1576 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1577 delete dlv;
1578 } while (deferred->length() != 0);
1579 delete deferred;
1580 }
1581
1582 // All Java related clean up happens in exit
1583 ThreadSafepointState::destroy(this);
1584 if (_thread_profiler != NULL) delete _thread_profiler;
1585 if (_thread_stat != NULL) delete _thread_stat;
1586 }
1587
1588
1589 // The first routine called by a new Java thread
1590 void JavaThread::run() {
1591 // initialize thread-local alloc buffer related fields
1592 this->initialize_tlab();
1593
1594 // used to test validity of stack trace backs
1595 this->record_base_of_stack_pointer();
1596
1597 // Record real stack base and size.
1598 this->record_stack_base_and_size();
1599
1600 // Initialize thread local storage; set before calling MutexLocker
1601 this->initialize_thread_local_storage();
1602
1603 this->create_stack_guard_pages();
1604
1605 this->cache_global_variables();
1606
1607 // Thread is now sufficient initialized to be handled by the safepoint code as being
1608 // in the VM. Change thread state from _thread_new to _thread_in_vm
1609 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1610
1611 assert(JavaThread::current() == this, "sanity check");
1612 assert(!Thread::current()->owns_locks(), "sanity check");
1613
1614 DTRACE_THREAD_PROBE(start, this);
1615
1616 // This operation might block. We call that after all safepoint checks for a new thread has
1617 // been completed.
1618 this->set_active_handles(JNIHandleBlock::allocate_block());
1619
1620 if (JvmtiExport::should_post_thread_life()) {
1621 JvmtiExport::post_thread_start(this);
1622 }
1623
1624 EventThreadStart event;
1625 if (event.should_commit()) {
1626 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1627 event.commit();
1628 }
1629
1630 // We call another function to do the rest so we are sure that the stack addresses used
1631 // from there will be lower than the stack base just computed
1632 thread_main_inner();
1633
1634 // Note, thread is no longer valid at this point!
1635 }
1636
1637
1638 void JavaThread::thread_main_inner() {
1639 assert(JavaThread::current() == this, "sanity check");
1640 assert(this->threadObj() != NULL, "just checking");
1641
1642 // Execute thread entry point unless this thread has a pending exception
1643 // or has been stopped before starting.
1644 // Note: Due to JVM_StopThread we can have pending exceptions already!
1645 if (!this->has_pending_exception() &&
1646 !java_lang_Thread::is_stillborn(this->threadObj())) {
1647 {
1648 ResourceMark rm(this);
1649 this->set_native_thread_name(this->get_thread_name());
1650 }
1651 HandleMark hm(this);
1652 this->entry_point()(this, this);
1653 }
1654
1655 DTRACE_THREAD_PROBE(stop, this);
1656
1657 this->exit(false);
1658 delete this;
1659 }
1660
1661
1662 static void ensure_join(JavaThread* thread) {
1663 // We do not need to grap the Threads_lock, since we are operating on ourself.
1664 Handle threadObj(thread, thread->threadObj());
1665 assert(threadObj.not_null(), "java thread object must exist");
1666 ObjectLocker lock(threadObj, thread);
1667 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1668 thread->clear_pending_exception();
1669 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1670 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1671 // Clear the native thread instance - this makes isAlive return false and allows the join()
1672 // to complete once we've done the notify_all below
1673 java_lang_Thread::set_thread(threadObj(), NULL);
1674 lock.notify_all(thread);
1675 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1676 thread->clear_pending_exception();
1677 }
1678
1679
1680 // For any new cleanup additions, please check to see if they need to be applied to
1681 // cleanup_failed_attach_current_thread as well.
1682 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1683 assert(this == JavaThread::current(), "thread consistency check");
1684
1685 HandleMark hm(this);
1686 Handle uncaught_exception(this, this->pending_exception());
1687 this->clear_pending_exception();
1688 Handle threadObj(this, this->threadObj());
1689 assert(threadObj.not_null(), "Java thread object should be created");
1690
1691 if (get_thread_profiler() != NULL) {
1692 get_thread_profiler()->disengage();
1693 ResourceMark rm;
1694 get_thread_profiler()->print(get_thread_name());
1695 }
1696
1697
1698 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1699 {
1700 EXCEPTION_MARK;
1701
1702 CLEAR_PENDING_EXCEPTION;
1703 }
1704 if (!destroy_vm) {
1705 if (uncaught_exception.not_null()) {
1706 EXCEPTION_MARK;
1707 // Call method Thread.dispatchUncaughtException().
1708 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1709 JavaValue result(T_VOID);
1710 JavaCalls::call_virtual(&result,
1711 threadObj, thread_klass,
1712 vmSymbols::dispatchUncaughtException_name(),
1713 vmSymbols::throwable_void_signature(),
1714 uncaught_exception,
1715 THREAD);
1716 if (HAS_PENDING_EXCEPTION) {
1717 ResourceMark rm(this);
1718 jio_fprintf(defaultStream::error_stream(),
1719 "\nException: %s thrown from the UncaughtExceptionHandler"
1720 " in thread \"%s\"\n",
1721 pending_exception()->klass()->external_name(),
1722 get_thread_name());
1723 CLEAR_PENDING_EXCEPTION;
1724 }
1725 }
1726
1727 // Called before the java thread exit since we want to read info
1728 // from java_lang_Thread object
1729 EventThreadEnd event;
1730 if (event.should_commit()) {
1731 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1732 event.commit();
1733 }
1734
1735 // Call after last event on thread
1736 EVENT_THREAD_EXIT(this);
1737
1738 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1739 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1740 // is deprecated anyhow.
1741 if (!is_Compiler_thread()) {
1742 int count = 3;
1743 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1744 EXCEPTION_MARK;
1745 JavaValue result(T_VOID);
1746 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1747 JavaCalls::call_virtual(&result,
1748 threadObj, thread_klass,
1749 vmSymbols::exit_method_name(),
1750 vmSymbols::void_method_signature(),
1751 THREAD);
1752 CLEAR_PENDING_EXCEPTION;
1753 }
1754 }
1755 // notify JVMTI
1756 if (JvmtiExport::should_post_thread_life()) {
1757 JvmtiExport::post_thread_end(this);
1758 }
1759
1760 // We have notified the agents that we are exiting, before we go on,
1761 // we must check for a pending external suspend request and honor it
1762 // in order to not surprise the thread that made the suspend request.
1763 while (true) {
1764 {
1765 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1766 if (!is_external_suspend()) {
1767 set_terminated(_thread_exiting);
1768 ThreadService::current_thread_exiting(this);
1769 break;
1770 }
1771 // Implied else:
1772 // Things get a little tricky here. We have a pending external
1773 // suspend request, but we are holding the SR_lock so we
1774 // can't just self-suspend. So we temporarily drop the lock
1775 // and then self-suspend.
1776 }
1777
1778 ThreadBlockInVM tbivm(this);
1779 java_suspend_self();
1780
1781 // We're done with this suspend request, but we have to loop around
1782 // and check again. Eventually we will get SR_lock without a pending
1783 // external suspend request and will be able to mark ourselves as
1784 // exiting.
1785 }
1786 // no more external suspends are allowed at this point
1787 } else {
1788 // before_exit() has already posted JVMTI THREAD_END events
1789 }
1790
1791 // Notify waiters on thread object. This has to be done after exit() is called
1792 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1793 // group should have the destroyed bit set before waiters are notified).
1794 ensure_join(this);
1795 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1796
1797 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1798 // held by this thread must be released. A detach operation must only
1799 // get here if there are no Java frames on the stack. Therefore, any
1800 // owned monitors at this point MUST be JNI-acquired monitors which are
1801 // pre-inflated and in the monitor cache.
1802 //
1803 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1804 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1805 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1806 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1807 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1808 }
1809
1810 // These things needs to be done while we are still a Java Thread. Make sure that thread
1811 // is in a consistent state, in case GC happens
1812 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1813
1814 if (active_handles() != NULL) {
1815 JNIHandleBlock* block = active_handles();
1816 set_active_handles(NULL);
1817 JNIHandleBlock::release_block(block);
1818 }
1819
1820 if (free_handle_block() != NULL) {
1821 JNIHandleBlock* block = free_handle_block();
1822 set_free_handle_block(NULL);
1823 JNIHandleBlock::release_block(block);
1824 }
1825
1826 // These have to be removed while this is still a valid thread.
1827 remove_stack_guard_pages();
1828
1829 if (UseTLAB) {
1830 tlab().make_parsable(true); // retire TLAB
1831 }
1832
1833 if (JvmtiEnv::environments_might_exist()) {
1834 JvmtiExport::cleanup_thread(this);
1835 }
1836
1837 // We must flush any deferred card marks before removing a thread from
1838 // the list of active threads.
1839 Universe::heap()->flush_deferred_store_barrier(this);
1840 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1841
1842 #if INCLUDE_ALL_GCS
1843 // We must flush the G1-related buffers before removing a thread
1844 // from the list of active threads. We must do this after any deferred
1845 // card marks have been flushed (above) so that any entries that are
1846 // added to the thread's dirty card queue as a result are not lost.
1847 if (UseG1GC) {
1848 flush_barrier_queues();
1849 }
1850 #endif // INCLUDE_ALL_GCS
1851
1852 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1853 Threads::remove(this);
1854 }
1855
1856 #if INCLUDE_ALL_GCS
1857 // Flush G1-related queues.
1858 void JavaThread::flush_barrier_queues() {
1859 satb_mark_queue().flush();
1860 dirty_card_queue().flush();
1861 }
1862
1863 void JavaThread::initialize_queues() {
1864 assert(!SafepointSynchronize::is_at_safepoint(),
1865 "we should not be at a safepoint");
1866
1867 ObjPtrQueue& satb_queue = satb_mark_queue();
1868 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1869 // The SATB queue should have been constructed with its active
1870 // field set to false.
1871 assert(!satb_queue.is_active(), "SATB queue should not be active");
1872 assert(satb_queue.is_empty(), "SATB queue should be empty");
1873 // If we are creating the thread during a marking cycle, we should
1874 // set the active field of the SATB queue to true.
1875 if (satb_queue_set.is_active()) {
1876 satb_queue.set_active(true);
1877 }
1878
1879 DirtyCardQueue& dirty_queue = dirty_card_queue();
1880 // The dirty card queue should have been constructed with its
1881 // active field set to true.
1882 assert(dirty_queue.is_active(), "dirty card queue should be active");
1883 }
1884 #endif // INCLUDE_ALL_GCS
1885
1886 void JavaThread::cleanup_failed_attach_current_thread() {
1887 if (get_thread_profiler() != NULL) {
1888 get_thread_profiler()->disengage();
1889 ResourceMark rm;
1890 get_thread_profiler()->print(get_thread_name());
1891 }
1892
1893 if (active_handles() != NULL) {
1894 JNIHandleBlock* block = active_handles();
1895 set_active_handles(NULL);
1896 JNIHandleBlock::release_block(block);
1897 }
1898
1899 if (free_handle_block() != NULL) {
1900 JNIHandleBlock* block = free_handle_block();
1901 set_free_handle_block(NULL);
1902 JNIHandleBlock::release_block(block);
1903 }
1904
1905 // These have to be removed while this is still a valid thread.
1906 remove_stack_guard_pages();
1907
1908 if (UseTLAB) {
1909 tlab().make_parsable(true); // retire TLAB, if any
1910 }
1911
1912 #if INCLUDE_ALL_GCS
1913 if (UseG1GC) {
1914 flush_barrier_queues();
1915 }
1916 #endif // INCLUDE_ALL_GCS
1917
1918 Threads::remove(this);
1919 delete this;
1920 }
1921
1922
1923
1924
1925 JavaThread* JavaThread::active() {
1926 Thread* thread = ThreadLocalStorage::thread();
1927 assert(thread != NULL, "just checking");
1928 if (thread->is_Java_thread()) {
1929 return (JavaThread*) thread;
1930 } else {
1931 assert(thread->is_VM_thread(), "this must be a vm thread");
1932 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1933 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1934 assert(ret->is_Java_thread(), "must be a Java thread");
1935 return ret;
1936 }
1937 }
1938
1939 bool JavaThread::is_lock_owned(address adr) const {
1940 if (Thread::is_lock_owned(adr)) return true;
1941
1942 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1943 if (chunk->contains(adr)) return true;
1944 }
1945
1946 return false;
1947 }
1948
1949
1950 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1951 chunk->set_next(monitor_chunks());
1952 set_monitor_chunks(chunk);
1953 }
1954
1955 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1956 guarantee(monitor_chunks() != NULL, "must be non empty");
1957 if (monitor_chunks() == chunk) {
1958 set_monitor_chunks(chunk->next());
1959 } else {
1960 MonitorChunk* prev = monitor_chunks();
1961 while (prev->next() != chunk) prev = prev->next();
1962 prev->set_next(chunk->next());
1963 }
1964 }
1965
1966 // JVM support.
1967
1968 // Note: this function shouldn't block if it's called in
1969 // _thread_in_native_trans state (such as from
1970 // check_special_condition_for_native_trans()).
1971 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1972
1973 if (has_last_Java_frame() && has_async_condition()) {
1974 // If we are at a polling page safepoint (not a poll return)
1975 // then we must defer async exception because live registers
1976 // will be clobbered by the exception path. Poll return is
1977 // ok because the call we a returning from already collides
1978 // with exception handling registers and so there is no issue.
1979 // (The exception handling path kills call result registers but
1980 // this is ok since the exception kills the result anyway).
1981
1982 if (is_at_poll_safepoint()) {
1983 // if the code we are returning to has deoptimized we must defer
1984 // the exception otherwise live registers get clobbered on the
1985 // exception path before deoptimization is able to retrieve them.
1986 //
1987 RegisterMap map(this, false);
1988 frame caller_fr = last_frame().sender(&map);
1989 assert(caller_fr.is_compiled_frame(), "what?");
1990 if (caller_fr.is_deoptimized_frame()) {
1991 if (TraceExceptions) {
1992 ResourceMark rm;
1993 tty->print_cr("deferred async exception at compiled safepoint");
1994 }
1995 return;
1996 }
1997 }
1998 }
1999
2000 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2001 if (condition == _no_async_condition) {
2002 // Conditions have changed since has_special_runtime_exit_condition()
2003 // was called:
2004 // - if we were here only because of an external suspend request,
2005 // then that was taken care of above (or cancelled) so we are done
2006 // - if we were here because of another async request, then it has
2007 // been cleared between the has_special_runtime_exit_condition()
2008 // and now so again we are done
2009 return;
2010 }
2011
2012 // Check for pending async. exception
2013 if (_pending_async_exception != NULL) {
2014 // Only overwrite an already pending exception, if it is not a threadDeath.
2015 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2016
2017 // We cannot call Exceptions::_throw(...) here because we cannot block
2018 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2019
2020 if (TraceExceptions) {
2021 ResourceMark rm;
2022 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2023 if (has_last_Java_frame()) {
2024 frame f = last_frame();
2025 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2026 }
2027 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2028 }
2029 _pending_async_exception = NULL;
2030 clear_has_async_exception();
2031 }
2032 }
2033
2034 if (check_unsafe_error &&
2035 condition == _async_unsafe_access_error && !has_pending_exception()) {
2036 condition = _no_async_condition; // done
2037 switch (thread_state()) {
2038 case _thread_in_vm: {
2039 JavaThread* THREAD = this;
2040 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2041 }
2042 case _thread_in_native: {
2043 ThreadInVMfromNative tiv(this);
2044 JavaThread* THREAD = this;
2045 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2046 }
2047 case _thread_in_Java: {
2048 ThreadInVMfromJava tiv(this);
2049 JavaThread* THREAD = this;
2050 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2051 }
2052 default:
2053 ShouldNotReachHere();
2054 }
2055 }
2056
2057 assert(condition == _no_async_condition || has_pending_exception() ||
2058 (!check_unsafe_error && condition == _async_unsafe_access_error),
2059 "must have handled the async condition, if no exception");
2060 }
2061
2062 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2063 //
2064 // Check for pending external suspend. Internal suspend requests do
2065 // not use handle_special_runtime_exit_condition().
2066 // If JNIEnv proxies are allowed, don't self-suspend if the target
2067 // thread is not the current thread. In older versions of jdbx, jdbx
2068 // threads could call into the VM with another thread's JNIEnv so we
2069 // can be here operating on behalf of a suspended thread (4432884).
2070 bool do_self_suspend = is_external_suspend_with_lock();
2071 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2072 //
2073 // Because thread is external suspended the safepoint code will count
2074 // thread as at a safepoint. This can be odd because we can be here
2075 // as _thread_in_Java which would normally transition to _thread_blocked
2076 // at a safepoint. We would like to mark the thread as _thread_blocked
2077 // before calling java_suspend_self like all other callers of it but
2078 // we must then observe proper safepoint protocol. (We can't leave
2079 // _thread_blocked with a safepoint in progress). However we can be
2080 // here as _thread_in_native_trans so we can't use a normal transition
2081 // constructor/destructor pair because they assert on that type of
2082 // transition. We could do something like:
2083 //
2084 // JavaThreadState state = thread_state();
2085 // set_thread_state(_thread_in_vm);
2086 // {
2087 // ThreadBlockInVM tbivm(this);
2088 // java_suspend_self()
2089 // }
2090 // set_thread_state(_thread_in_vm_trans);
2091 // if (safepoint) block;
2092 // set_thread_state(state);
2093 //
2094 // but that is pretty messy. Instead we just go with the way the
2095 // code has worked before and note that this is the only path to
2096 // java_suspend_self that doesn't put the thread in _thread_blocked
2097 // mode.
2098
2099 frame_anchor()->make_walkable(this);
2100 java_suspend_self();
2101
2102 // We might be here for reasons in addition to the self-suspend request
2103 // so check for other async requests.
2104 }
2105
2106 if (check_asyncs) {
2107 check_and_handle_async_exceptions();
2108 }
2109 }
2110
2111 void JavaThread::send_thread_stop(oop java_throwable) {
2112 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2113 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2114 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2115
2116 // Do not throw asynchronous exceptions against the compiler thread
2117 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2118 if (is_Compiler_thread()) return;
2119
2120 {
2121 // Actually throw the Throwable against the target Thread - however
2122 // only if there is no thread death exception installed already.
2123 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2124 // If the topmost frame is a runtime stub, then we are calling into
2125 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2126 // must deoptimize the caller before continuing, as the compiled exception handler table
2127 // may not be valid
2128 if (has_last_Java_frame()) {
2129 frame f = last_frame();
2130 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2131 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2132 RegisterMap reg_map(this, UseBiasedLocking);
2133 frame compiled_frame = f.sender(®_map);
2134 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2135 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2136 }
2137 }
2138 }
2139
2140 // Set async. pending exception in thread.
2141 set_pending_async_exception(java_throwable);
2142
2143 if (TraceExceptions) {
2144 ResourceMark rm;
2145 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2146 }
2147 // for AbortVMOnException flag
2148 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2149 }
2150 }
2151
2152
2153 // Interrupt thread so it will wake up from a potential wait()
2154 Thread::interrupt(this);
2155 }
2156
2157 // External suspension mechanism.
2158 //
2159 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2160 // to any VM_locks and it is at a transition
2161 // Self-suspension will happen on the transition out of the vm.
2162 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2163 //
2164 // Guarantees on return:
2165 // + Target thread will not execute any new bytecode (that's why we need to
2166 // force a safepoint)
2167 // + Target thread will not enter any new monitors
2168 //
2169 void JavaThread::java_suspend() {
2170 { MutexLocker mu(Threads_lock);
2171 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2172 return;
2173 }
2174 }
2175
2176 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2177 if (!is_external_suspend()) {
2178 // a racing resume has cancelled us; bail out now
2179 return;
2180 }
2181
2182 // suspend is done
2183 uint32_t debug_bits = 0;
2184 // Warning: is_ext_suspend_completed() may temporarily drop the
2185 // SR_lock to allow the thread to reach a stable thread state if
2186 // it is currently in a transient thread state.
2187 if (is_ext_suspend_completed(false /* !called_by_wait */,
2188 SuspendRetryDelay, &debug_bits)) {
2189 return;
2190 }
2191 }
2192
2193 VM_ForceSafepoint vm_suspend;
2194 VMThread::execute(&vm_suspend);
2195 }
2196
2197 // Part II of external suspension.
2198 // A JavaThread self suspends when it detects a pending external suspend
2199 // request. This is usually on transitions. It is also done in places
2200 // where continuing to the next transition would surprise the caller,
2201 // e.g., monitor entry.
2202 //
2203 // Returns the number of times that the thread self-suspended.
2204 //
2205 // Note: DO NOT call java_suspend_self() when you just want to block current
2206 // thread. java_suspend_self() is the second stage of cooperative
2207 // suspension for external suspend requests and should only be used
2208 // to complete an external suspend request.
2209 //
2210 int JavaThread::java_suspend_self() {
2211 int ret = 0;
2212
2213 // we are in the process of exiting so don't suspend
2214 if (is_exiting()) {
2215 clear_external_suspend();
2216 return ret;
2217 }
2218
2219 assert(_anchor.walkable() ||
2220 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2221 "must have walkable stack");
2222
2223 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2224
2225 assert(!this->is_ext_suspended(),
2226 "a thread trying to self-suspend should not already be suspended");
2227
2228 if (this->is_suspend_equivalent()) {
2229 // If we are self-suspending as a result of the lifting of a
2230 // suspend equivalent condition, then the suspend_equivalent
2231 // flag is not cleared until we set the ext_suspended flag so
2232 // that wait_for_ext_suspend_completion() returns consistent
2233 // results.
2234 this->clear_suspend_equivalent();
2235 }
2236
2237 // A racing resume may have cancelled us before we grabbed SR_lock
2238 // above. Or another external suspend request could be waiting for us
2239 // by the time we return from SR_lock()->wait(). The thread
2240 // that requested the suspension may already be trying to walk our
2241 // stack and if we return now, we can change the stack out from under
2242 // it. This would be a "bad thing (TM)" and cause the stack walker
2243 // to crash. We stay self-suspended until there are no more pending
2244 // external suspend requests.
2245 while (is_external_suspend()) {
2246 ret++;
2247 this->set_ext_suspended();
2248
2249 // _ext_suspended flag is cleared by java_resume()
2250 while (is_ext_suspended()) {
2251 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2252 }
2253 }
2254
2255 return ret;
2256 }
2257
2258 #ifdef ASSERT
2259 // verify the JavaThread has not yet been published in the Threads::list, and
2260 // hence doesn't need protection from concurrent access at this stage
2261 void JavaThread::verify_not_published() {
2262 if (!Threads_lock->owned_by_self()) {
2263 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2264 assert(!Threads::includes(this),
2265 "java thread shouldn't have been published yet!");
2266 } else {
2267 assert(!Threads::includes(this),
2268 "java thread shouldn't have been published yet!");
2269 }
2270 }
2271 #endif
2272
2273 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2274 // progress or when _suspend_flags is non-zero.
2275 // Current thread needs to self-suspend if there is a suspend request and/or
2276 // block if a safepoint is in progress.
2277 // Async exception ISN'T checked.
2278 // Note only the ThreadInVMfromNative transition can call this function
2279 // directly and when thread state is _thread_in_native_trans
2280 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2281 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2282
2283 JavaThread *curJT = JavaThread::current();
2284 bool do_self_suspend = thread->is_external_suspend();
2285
2286 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2287
2288 // If JNIEnv proxies are allowed, don't self-suspend if the target
2289 // thread is not the current thread. In older versions of jdbx, jdbx
2290 // threads could call into the VM with another thread's JNIEnv so we
2291 // can be here operating on behalf of a suspended thread (4432884).
2292 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2293 JavaThreadState state = thread->thread_state();
2294
2295 // We mark this thread_blocked state as a suspend-equivalent so
2296 // that a caller to is_ext_suspend_completed() won't be confused.
2297 // The suspend-equivalent state is cleared by java_suspend_self().
2298 thread->set_suspend_equivalent();
2299
2300 // If the safepoint code sees the _thread_in_native_trans state, it will
2301 // wait until the thread changes to other thread state. There is no
2302 // guarantee on how soon we can obtain the SR_lock and complete the
2303 // self-suspend request. It would be a bad idea to let safepoint wait for
2304 // too long. Temporarily change the state to _thread_blocked to
2305 // let the VM thread know that this thread is ready for GC. The problem
2306 // of changing thread state is that safepoint could happen just after
2307 // java_suspend_self() returns after being resumed, and VM thread will
2308 // see the _thread_blocked state. We must check for safepoint
2309 // after restoring the state and make sure we won't leave while a safepoint
2310 // is in progress.
2311 thread->set_thread_state(_thread_blocked);
2312 thread->java_suspend_self();
2313 thread->set_thread_state(state);
2314 // Make sure new state is seen by VM thread
2315 if (os::is_MP()) {
2316 if (UseMembar) {
2317 // Force a fence between the write above and read below
2318 OrderAccess::fence();
2319 } else {
2320 // Must use this rather than serialization page in particular on Windows
2321 InterfaceSupport::serialize_memory(thread);
2322 }
2323 }
2324 }
2325
2326 if (SafepointSynchronize::do_call_back()) {
2327 // If we are safepointing, then block the caller which may not be
2328 // the same as the target thread (see above).
2329 SafepointSynchronize::block(curJT);
2330 }
2331
2332 if (thread->is_deopt_suspend()) {
2333 thread->clear_deopt_suspend();
2334 RegisterMap map(thread, false);
2335 frame f = thread->last_frame();
2336 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2337 f = f.sender(&map);
2338 }
2339 if (f.id() == thread->must_deopt_id()) {
2340 thread->clear_must_deopt_id();
2341 f.deoptimize(thread);
2342 } else {
2343 fatal("missed deoptimization!");
2344 }
2345 }
2346 }
2347
2348 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2349 // progress or when _suspend_flags is non-zero.
2350 // Current thread needs to self-suspend if there is a suspend request and/or
2351 // block if a safepoint is in progress.
2352 // Also check for pending async exception (not including unsafe access error).
2353 // Note only the native==>VM/Java barriers can call this function and when
2354 // thread state is _thread_in_native_trans.
2355 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2356 check_safepoint_and_suspend_for_native_trans(thread);
2357
2358 if (thread->has_async_exception()) {
2359 // We are in _thread_in_native_trans state, don't handle unsafe
2360 // access error since that may block.
2361 thread->check_and_handle_async_exceptions(false);
2362 }
2363 }
2364
2365 // This is a variant of the normal
2366 // check_special_condition_for_native_trans with slightly different
2367 // semantics for use by critical native wrappers. It does all the
2368 // normal checks but also performs the transition back into
2369 // thread_in_Java state. This is required so that critical natives
2370 // can potentially block and perform a GC if they are the last thread
2371 // exiting the GC_locker.
2372 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2373 check_special_condition_for_native_trans(thread);
2374
2375 // Finish the transition
2376 thread->set_thread_state(_thread_in_Java);
2377
2378 if (thread->do_critical_native_unlock()) {
2379 ThreadInVMfromJavaNoAsyncException tiv(thread);
2380 GC_locker::unlock_critical(thread);
2381 thread->clear_critical_native_unlock();
2382 }
2383 }
2384
2385 // We need to guarantee the Threads_lock here, since resumes are not
2386 // allowed during safepoint synchronization
2387 // Can only resume from an external suspension
2388 void JavaThread::java_resume() {
2389 assert_locked_or_safepoint(Threads_lock);
2390
2391 // Sanity check: thread is gone, has started exiting or the thread
2392 // was not externally suspended.
2393 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2394 return;
2395 }
2396
2397 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2398
2399 clear_external_suspend();
2400
2401 if (is_ext_suspended()) {
2402 clear_ext_suspended();
2403 SR_lock()->notify_all();
2404 }
2405 }
2406
2407 void JavaThread::create_stack_guard_pages() {
2408 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2409 address low_addr = stack_base() - stack_size();
2410 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2411
2412 int allocate = os::allocate_stack_guard_pages();
2413 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2414
2415 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2416 warning("Attempt to allocate stack guard pages failed.");
2417 return;
2418 }
2419
2420 if (os::guard_memory((char *) low_addr, len)) {
2421 _stack_guard_state = stack_guard_enabled;
2422 } else {
2423 warning("Attempt to protect stack guard pages failed.");
2424 if (os::uncommit_memory((char *) low_addr, len)) {
2425 warning("Attempt to deallocate stack guard pages failed.");
2426 }
2427 }
2428 }
2429
2430 void JavaThread::remove_stack_guard_pages() {
2431 assert(Thread::current() == this, "from different thread");
2432 if (_stack_guard_state == stack_guard_unused) return;
2433 address low_addr = stack_base() - stack_size();
2434 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2435
2436 if (os::allocate_stack_guard_pages()) {
2437 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2438 _stack_guard_state = stack_guard_unused;
2439 } else {
2440 warning("Attempt to deallocate stack guard pages failed.");
2441 }
2442 } else {
2443 if (_stack_guard_state == stack_guard_unused) return;
2444 if (os::unguard_memory((char *) low_addr, len)) {
2445 _stack_guard_state = stack_guard_unused;
2446 } else {
2447 warning("Attempt to unprotect stack guard pages failed.");
2448 }
2449 }
2450 }
2451
2452 void JavaThread::enable_stack_yellow_zone() {
2453 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2454 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2455
2456 // The base notation is from the stacks point of view, growing downward.
2457 // We need to adjust it to work correctly with guard_memory()
2458 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2459
2460 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2461 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2462
2463 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2464 _stack_guard_state = stack_guard_enabled;
2465 } else {
2466 warning("Attempt to guard stack yellow zone failed.");
2467 }
2468 enable_register_stack_guard();
2469 }
2470
2471 void JavaThread::disable_stack_yellow_zone() {
2472 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2473 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2474
2475 // Simply return if called for a thread that does not use guard pages.
2476 if (_stack_guard_state == stack_guard_unused) return;
2477
2478 // The base notation is from the stacks point of view, growing downward.
2479 // We need to adjust it to work correctly with guard_memory()
2480 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2481
2482 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2483 _stack_guard_state = stack_guard_yellow_disabled;
2484 } else {
2485 warning("Attempt to unguard stack yellow zone failed.");
2486 }
2487 disable_register_stack_guard();
2488 }
2489
2490 void JavaThread::enable_stack_red_zone() {
2491 // The base notation is from the stacks point of view, growing downward.
2492 // We need to adjust it to work correctly with guard_memory()
2493 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2494 address base = stack_red_zone_base() - stack_red_zone_size();
2495
2496 guarantee(base < stack_base(), "Error calculating stack red zone");
2497 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2498
2499 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2500 warning("Attempt to guard stack red zone failed.");
2501 }
2502 }
2503
2504 void JavaThread::disable_stack_red_zone() {
2505 // The base notation is from the stacks point of view, growing downward.
2506 // We need to adjust it to work correctly with guard_memory()
2507 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2508 address base = stack_red_zone_base() - stack_red_zone_size();
2509 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2510 warning("Attempt to unguard stack red zone failed.");
2511 }
2512 }
2513
2514 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2515 // ignore is there is no stack
2516 if (!has_last_Java_frame()) return;
2517 // traverse the stack frames. Starts from top frame.
2518 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2519 frame* fr = fst.current();
2520 f(fr, fst.register_map());
2521 }
2522 }
2523
2524
2525 #ifndef PRODUCT
2526 // Deoptimization
2527 // Function for testing deoptimization
2528 void JavaThread::deoptimize() {
2529 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2530 StackFrameStream fst(this, UseBiasedLocking);
2531 bool deopt = false; // Dump stack only if a deopt actually happens.
2532 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2533 // Iterate over all frames in the thread and deoptimize
2534 for (; !fst.is_done(); fst.next()) {
2535 if (fst.current()->can_be_deoptimized()) {
2536
2537 if (only_at) {
2538 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2539 // consists of comma or carriage return separated numbers so
2540 // search for the current bci in that string.
2541 address pc = fst.current()->pc();
2542 nmethod* nm = (nmethod*) fst.current()->cb();
2543 ScopeDesc* sd = nm->scope_desc_at(pc);
2544 char buffer[8];
2545 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2546 size_t len = strlen(buffer);
2547 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2548 while (found != NULL) {
2549 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2550 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2551 // Check that the bci found is bracketed by terminators.
2552 break;
2553 }
2554 found = strstr(found + 1, buffer);
2555 }
2556 if (!found) {
2557 continue;
2558 }
2559 }
2560
2561 if (DebugDeoptimization && !deopt) {
2562 deopt = true; // One-time only print before deopt
2563 tty->print_cr("[BEFORE Deoptimization]");
2564 trace_frames();
2565 trace_stack();
2566 }
2567 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2568 }
2569 }
2570
2571 if (DebugDeoptimization && deopt) {
2572 tty->print_cr("[AFTER Deoptimization]");
2573 trace_frames();
2574 }
2575 }
2576
2577
2578 // Make zombies
2579 void JavaThread::make_zombies() {
2580 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2581 if (fst.current()->can_be_deoptimized()) {
2582 // it is a Java nmethod
2583 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2584 nm->make_not_entrant();
2585 }
2586 }
2587 }
2588 #endif // PRODUCT
2589
2590
2591 void JavaThread::deoptimized_wrt_marked_nmethods() {
2592 if (!has_last_Java_frame()) return;
2593 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2594 StackFrameStream fst(this, UseBiasedLocking);
2595 for (; !fst.is_done(); fst.next()) {
2596 if (fst.current()->should_be_deoptimized()) {
2597 if (LogCompilation && xtty != NULL) {
2598 nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2599 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2600 this->name(), nm != NULL ? nm->compile_id() : -1);
2601 }
2602
2603 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2604 }
2605 }
2606 }
2607
2608
2609 // If the caller is a NamedThread, then remember, in the current scope,
2610 // the given JavaThread in its _processed_thread field.
2611 class RememberProcessedThread: public StackObj {
2612 NamedThread* _cur_thr;
2613 public:
2614 RememberProcessedThread(JavaThread* jthr) {
2615 Thread* thread = Thread::current();
2616 if (thread->is_Named_thread()) {
2617 _cur_thr = (NamedThread *)thread;
2618 _cur_thr->set_processed_thread(jthr);
2619 } else {
2620 _cur_thr = NULL;
2621 }
2622 }
2623
2624 ~RememberProcessedThread() {
2625 if (_cur_thr) {
2626 _cur_thr->set_processed_thread(NULL);
2627 }
2628 }
2629 };
2630
2631 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2632 // Verify that the deferred card marks have been flushed.
2633 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2634
2635 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2636 // since there may be more than one thread using each ThreadProfiler.
2637
2638 // Traverse the GCHandles
2639 Thread::oops_do(f, cld_f, cf);
2640
2641 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2642 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2643
2644 if (has_last_Java_frame()) {
2645 // Record JavaThread to GC thread
2646 RememberProcessedThread rpt(this);
2647
2648 // Traverse the privileged stack
2649 if (_privileged_stack_top != NULL) {
2650 _privileged_stack_top->oops_do(f);
2651 }
2652
2653 // traverse the registered growable array
2654 if (_array_for_gc != NULL) {
2655 for (int index = 0; index < _array_for_gc->length(); index++) {
2656 f->do_oop(_array_for_gc->adr_at(index));
2657 }
2658 }
2659
2660 // Traverse the monitor chunks
2661 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2662 chunk->oops_do(f);
2663 }
2664
2665 // Traverse the execution stack
2666 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2667 fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2668 }
2669 }
2670
2671 // callee_target is never live across a gc point so NULL it here should
2672 // it still contain a methdOop.
2673
2674 set_callee_target(NULL);
2675
2676 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2677 // If we have deferred set_locals there might be oops waiting to be
2678 // written
2679 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2680 if (list != NULL) {
2681 for (int i = 0; i < list->length(); i++) {
2682 list->at(i)->oops_do(f);
2683 }
2684 }
2685
2686 // Traverse instance variables at the end since the GC may be moving things
2687 // around using this function
2688 f->do_oop((oop*) &_threadObj);
2689 f->do_oop((oop*) &_vm_result);
2690 f->do_oop((oop*) &_exception_oop);
2691 f->do_oop((oop*) &_pending_async_exception);
2692
2693 if (jvmti_thread_state() != NULL) {
2694 jvmti_thread_state()->oops_do(f);
2695 }
2696 }
2697
2698 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2699 Thread::nmethods_do(cf); // (super method is a no-op)
2700
2701 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2702 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2703
2704 if (has_last_Java_frame()) {
2705 // Traverse the execution stack
2706 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2707 fst.current()->nmethods_do(cf);
2708 }
2709 }
2710 }
2711
2712 void JavaThread::metadata_do(void f(Metadata*)) {
2713 Thread::metadata_do(f);
2714 if (has_last_Java_frame()) {
2715 // Traverse the execution stack to call f() on the methods in the stack
2716 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2717 fst.current()->metadata_do(f);
2718 }
2719 } else if (is_Compiler_thread()) {
2720 // need to walk ciMetadata in current compile tasks to keep alive.
2721 CompilerThread* ct = (CompilerThread*)this;
2722 if (ct->env() != NULL) {
2723 ct->env()->metadata_do(f);
2724 }
2725 }
2726 }
2727
2728 // Printing
2729 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2730 switch (_thread_state) {
2731 case _thread_uninitialized: return "_thread_uninitialized";
2732 case _thread_new: return "_thread_new";
2733 case _thread_new_trans: return "_thread_new_trans";
2734 case _thread_in_native: return "_thread_in_native";
2735 case _thread_in_native_trans: return "_thread_in_native_trans";
2736 case _thread_in_vm: return "_thread_in_vm";
2737 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2738 case _thread_in_Java: return "_thread_in_Java";
2739 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2740 case _thread_blocked: return "_thread_blocked";
2741 case _thread_blocked_trans: return "_thread_blocked_trans";
2742 default: return "unknown thread state";
2743 }
2744 }
2745
2746 #ifndef PRODUCT
2747 void JavaThread::print_thread_state_on(outputStream *st) const {
2748 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2749 };
2750 void JavaThread::print_thread_state() const {
2751 print_thread_state_on(tty);
2752 }
2753 #endif // PRODUCT
2754
2755 // Called by Threads::print() for VM_PrintThreads operation
2756 void JavaThread::print_on(outputStream *st) const {
2757 st->print("\"%s\" ", get_thread_name());
2758 oop thread_oop = threadObj();
2759 if (thread_oop != NULL) {
2760 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2761 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2762 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2763 }
2764 Thread::print_on(st);
2765 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2766 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2767 if (thread_oop != NULL) {
2768 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2769 }
2770 #ifndef PRODUCT
2771 print_thread_state_on(st);
2772 _safepoint_state->print_on(st);
2773 #endif // PRODUCT
2774 }
2775
2776 // Called by fatal error handler. The difference between this and
2777 // JavaThread::print() is that we can't grab lock or allocate memory.
2778 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2779 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2780 oop thread_obj = threadObj();
2781 if (thread_obj != NULL) {
2782 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2783 }
2784 st->print(" [");
2785 st->print("%s", _get_thread_state_name(_thread_state));
2786 if (osthread()) {
2787 st->print(", id=%d", osthread()->thread_id());
2788 }
2789 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2790 _stack_base - _stack_size, _stack_base);
2791 st->print("]");
2792 return;
2793 }
2794
2795 // Verification
2796
2797 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2798
2799 void JavaThread::verify() {
2800 // Verify oops in the thread.
2801 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2802
2803 // Verify the stack frames.
2804 frames_do(frame_verify);
2805 }
2806
2807 // CR 6300358 (sub-CR 2137150)
2808 // Most callers of this method assume that it can't return NULL but a
2809 // thread may not have a name whilst it is in the process of attaching to
2810 // the VM - see CR 6412693, and there are places where a JavaThread can be
2811 // seen prior to having it's threadObj set (eg JNI attaching threads and
2812 // if vm exit occurs during initialization). These cases can all be accounted
2813 // for such that this method never returns NULL.
2814 const char* JavaThread::get_thread_name() const {
2815 #ifdef ASSERT
2816 // early safepoints can hit while current thread does not yet have TLS
2817 if (!SafepointSynchronize::is_at_safepoint()) {
2818 Thread *cur = Thread::current();
2819 if (!(cur->is_Java_thread() && cur == this)) {
2820 // Current JavaThreads are allowed to get their own name without
2821 // the Threads_lock.
2822 assert_locked_or_safepoint(Threads_lock);
2823 }
2824 }
2825 #endif // ASSERT
2826 return get_thread_name_string();
2827 }
2828
2829 // Returns a non-NULL representation of this thread's name, or a suitable
2830 // descriptive string if there is no set name
2831 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2832 const char* name_str;
2833 oop thread_obj = threadObj();
2834 if (thread_obj != NULL) {
2835 oop name = java_lang_Thread::name(thread_obj);
2836 if (name != NULL) {
2837 if (buf == NULL) {
2838 name_str = java_lang_String::as_utf8_string(name);
2839 } else {
2840 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2841 }
2842 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2843 name_str = "<no-name - thread is attaching>";
2844 } else {
2845 name_str = Thread::name();
2846 }
2847 } else {
2848 name_str = Thread::name();
2849 }
2850 assert(name_str != NULL, "unexpected NULL thread name");
2851 return name_str;
2852 }
2853
2854
2855 const char* JavaThread::get_threadgroup_name() const {
2856 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2857 oop thread_obj = threadObj();
2858 if (thread_obj != NULL) {
2859 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2860 if (thread_group != NULL) {
2861 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2862 // ThreadGroup.name can be null
2863 if (name != NULL) {
2864 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2865 return str;
2866 }
2867 }
2868 }
2869 return NULL;
2870 }
2871
2872 const char* JavaThread::get_parent_name() const {
2873 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2874 oop thread_obj = threadObj();
2875 if (thread_obj != NULL) {
2876 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2877 if (thread_group != NULL) {
2878 oop parent = java_lang_ThreadGroup::parent(thread_group);
2879 if (parent != NULL) {
2880 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2881 // ThreadGroup.name can be null
2882 if (name != NULL) {
2883 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2884 return str;
2885 }
2886 }
2887 }
2888 }
2889 return NULL;
2890 }
2891
2892 ThreadPriority JavaThread::java_priority() const {
2893 oop thr_oop = threadObj();
2894 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2895 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2896 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2897 return priority;
2898 }
2899
2900 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2901
2902 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2903 // Link Java Thread object <-> C++ Thread
2904
2905 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2906 // and put it into a new Handle. The Handle "thread_oop" can then
2907 // be used to pass the C++ thread object to other methods.
2908
2909 // Set the Java level thread object (jthread) field of the
2910 // new thread (a JavaThread *) to C++ thread object using the
2911 // "thread_oop" handle.
2912
2913 // Set the thread field (a JavaThread *) of the
2914 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2915
2916 Handle thread_oop(Thread::current(),
2917 JNIHandles::resolve_non_null(jni_thread));
2918 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2919 "must be initialized");
2920 set_threadObj(thread_oop());
2921 java_lang_Thread::set_thread(thread_oop(), this);
2922
2923 if (prio == NoPriority) {
2924 prio = java_lang_Thread::priority(thread_oop());
2925 assert(prio != NoPriority, "A valid priority should be present");
2926 }
2927
2928 // Push the Java priority down to the native thread; needs Threads_lock
2929 Thread::set_priority(this, prio);
2930
2931 prepare_ext();
2932
2933 // Add the new thread to the Threads list and set it in motion.
2934 // We must have threads lock in order to call Threads::add.
2935 // It is crucial that we do not block before the thread is
2936 // added to the Threads list for if a GC happens, then the java_thread oop
2937 // will not be visited by GC.
2938 Threads::add(this);
2939 }
2940
2941 oop JavaThread::current_park_blocker() {
2942 // Support for JSR-166 locks
2943 oop thread_oop = threadObj();
2944 if (thread_oop != NULL &&
2945 JDK_Version::current().supports_thread_park_blocker()) {
2946 return java_lang_Thread::park_blocker(thread_oop);
2947 }
2948 return NULL;
2949 }
2950
2951
2952 void JavaThread::print_stack_on(outputStream* st) {
2953 if (!has_last_Java_frame()) return;
2954 ResourceMark rm;
2955 HandleMark hm;
2956
2957 RegisterMap reg_map(this);
2958 vframe* start_vf = last_java_vframe(®_map);
2959 int count = 0;
2960 for (vframe* f = start_vf; f; f = f->sender()) {
2961 if (f->is_java_frame()) {
2962 javaVFrame* jvf = javaVFrame::cast(f);
2963 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2964
2965 // Print out lock information
2966 if (JavaMonitorsInStackTrace) {
2967 jvf->print_lock_info_on(st, count);
2968 }
2969 } else {
2970 // Ignore non-Java frames
2971 }
2972
2973 // Bail-out case for too deep stacks
2974 count++;
2975 if (MaxJavaStackTraceDepth == count) return;
2976 }
2977 }
2978
2979
2980 // JVMTI PopFrame support
2981 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2982 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2983 if (in_bytes(size_in_bytes) != 0) {
2984 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2985 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2986 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2987 }
2988 }
2989
2990 void* JavaThread::popframe_preserved_args() {
2991 return _popframe_preserved_args;
2992 }
2993
2994 ByteSize JavaThread::popframe_preserved_args_size() {
2995 return in_ByteSize(_popframe_preserved_args_size);
2996 }
2997
2998 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2999 int sz = in_bytes(popframe_preserved_args_size());
3000 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3001 return in_WordSize(sz / wordSize);
3002 }
3003
3004 void JavaThread::popframe_free_preserved_args() {
3005 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3006 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3007 _popframe_preserved_args = NULL;
3008 _popframe_preserved_args_size = 0;
3009 }
3010
3011 #ifndef PRODUCT
3012
3013 void JavaThread::trace_frames() {
3014 tty->print_cr("[Describe stack]");
3015 int frame_no = 1;
3016 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3017 tty->print(" %d. ", frame_no++);
3018 fst.current()->print_value_on(tty, this);
3019 tty->cr();
3020 }
3021 }
3022
3023 class PrintAndVerifyOopClosure: public OopClosure {
3024 protected:
3025 template <class T> inline void do_oop_work(T* p) {
3026 oop obj = oopDesc::load_decode_heap_oop(p);
3027 if (obj == NULL) return;
3028 tty->print(INTPTR_FORMAT ": ", p);
3029 if (obj->is_oop_or_null()) {
3030 if (obj->is_objArray()) {
3031 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3032 } else {
3033 obj->print();
3034 }
3035 } else {
3036 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3037 }
3038 tty->cr();
3039 }
3040 public:
3041 virtual void do_oop(oop* p) { do_oop_work(p); }
3042 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3043 };
3044
3045
3046 static void oops_print(frame* f, const RegisterMap *map) {
3047 PrintAndVerifyOopClosure print;
3048 f->print_value();
3049 f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3050 }
3051
3052 // Print our all the locations that contain oops and whether they are
3053 // valid or not. This useful when trying to find the oldest frame
3054 // where an oop has gone bad since the frame walk is from youngest to
3055 // oldest.
3056 void JavaThread::trace_oops() {
3057 tty->print_cr("[Trace oops]");
3058 frames_do(oops_print);
3059 }
3060
3061
3062 #ifdef ASSERT
3063 // Print or validate the layout of stack frames
3064 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3065 ResourceMark rm;
3066 PRESERVE_EXCEPTION_MARK;
3067 FrameValues values;
3068 int frame_no = 0;
3069 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3070 fst.current()->describe(values, ++frame_no);
3071 if (depth == frame_no) break;
3072 }
3073 if (validate_only) {
3074 values.validate();
3075 } else {
3076 tty->print_cr("[Describe stack layout]");
3077 values.print(this);
3078 }
3079 }
3080 #endif
3081
3082 void JavaThread::trace_stack_from(vframe* start_vf) {
3083 ResourceMark rm;
3084 int vframe_no = 1;
3085 for (vframe* f = start_vf; f; f = f->sender()) {
3086 if (f->is_java_frame()) {
3087 javaVFrame::cast(f)->print_activation(vframe_no++);
3088 } else {
3089 f->print();
3090 }
3091 if (vframe_no > StackPrintLimit) {
3092 tty->print_cr("...<more frames>...");
3093 return;
3094 }
3095 }
3096 }
3097
3098
3099 void JavaThread::trace_stack() {
3100 if (!has_last_Java_frame()) return;
3101 ResourceMark rm;
3102 HandleMark hm;
3103 RegisterMap reg_map(this);
3104 trace_stack_from(last_java_vframe(®_map));
3105 }
3106
3107
3108 #endif // PRODUCT
3109
3110
3111 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3112 assert(reg_map != NULL, "a map must be given");
3113 frame f = last_frame();
3114 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3115 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3116 }
3117 return NULL;
3118 }
3119
3120
3121 Klass* JavaThread::security_get_caller_class(int depth) {
3122 vframeStream vfst(this);
3123 vfst.security_get_caller_frame(depth);
3124 if (!vfst.at_end()) {
3125 return vfst.method()->method_holder();
3126 }
3127 return NULL;
3128 }
3129
3130 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3131 assert(thread->is_Compiler_thread(), "must be compiler thread");
3132 CompileBroker::compiler_thread_loop();
3133 }
3134
3135 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3136 NMethodSweeper::sweeper_loop();
3137 }
3138
3139 // Create a CompilerThread
3140 CompilerThread::CompilerThread(CompileQueue* queue,
3141 CompilerCounters* counters)
3142 : JavaThread(&compiler_thread_entry) {
3143 _env = NULL;
3144 _log = NULL;
3145 _task = NULL;
3146 _queue = queue;
3147 _counters = counters;
3148 _buffer_blob = NULL;
3149 _compiler = NULL;
3150
3151 #ifndef PRODUCT
3152 _ideal_graph_printer = NULL;
3153 #endif
3154 }
3155
3156 // Create sweeper thread
3157 CodeCacheSweeperThread::CodeCacheSweeperThread()
3158 : JavaThread(&sweeper_thread_entry) {
3159 _scanned_nmethod = NULL;
3160 }
3161 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3162 JavaThread::oops_do(f, cld_f, cf);
3163 if (_scanned_nmethod != NULL && cf != NULL) {
3164 // Safepoints can occur when the sweeper is scanning an nmethod so
3165 // process it here to make sure it isn't unloaded in the middle of
3166 // a scan.
3167 cf->do_code_blob(_scanned_nmethod);
3168 }
3169 }
3170
3171
3172 // ======= Threads ========
3173
3174 // The Threads class links together all active threads, and provides
3175 // operations over all threads. It is protected by its own Mutex
3176 // lock, which is also used in other contexts to protect thread
3177 // operations from having the thread being operated on from exiting
3178 // and going away unexpectedly (e.g., safepoint synchronization)
3179
3180 JavaThread* Threads::_thread_list = NULL;
3181 int Threads::_number_of_threads = 0;
3182 int Threads::_number_of_non_daemon_threads = 0;
3183 int Threads::_return_code = 0;
3184 size_t JavaThread::_stack_size_at_create = 0;
3185 #ifdef ASSERT
3186 bool Threads::_vm_complete = false;
3187 #endif
3188
3189 // All JavaThreads
3190 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3191
3192 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3193 void Threads::threads_do(ThreadClosure* tc) {
3194 assert_locked_or_safepoint(Threads_lock);
3195 // ALL_JAVA_THREADS iterates through all JavaThreads
3196 ALL_JAVA_THREADS(p) {
3197 tc->do_thread(p);
3198 }
3199 // Someday we could have a table or list of all non-JavaThreads.
3200 // For now, just manually iterate through them.
3201 tc->do_thread(VMThread::vm_thread());
3202 Universe::heap()->gc_threads_do(tc);
3203 WatcherThread *wt = WatcherThread::watcher_thread();
3204 // Strictly speaking, the following NULL check isn't sufficient to make sure
3205 // the data for WatcherThread is still valid upon being examined. However,
3206 // considering that WatchThread terminates when the VM is on the way to
3207 // exit at safepoint, the chance of the above is extremely small. The right
3208 // way to prevent termination of WatcherThread would be to acquire
3209 // Terminator_lock, but we can't do that without violating the lock rank
3210 // checking in some cases.
3211 if (wt != NULL) {
3212 tc->do_thread(wt);
3213 }
3214
3215 // If CompilerThreads ever become non-JavaThreads, add them here
3216 }
3217
3218
3219 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3220 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3221
3222 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3223 create_vm_init_libraries();
3224 }
3225
3226 initialize_class(vmSymbols::java_lang_String(), CHECK);
3227
3228 // Initialize java_lang.System (needed before creating the thread)
3229 initialize_class(vmSymbols::java_lang_System(), CHECK);
3230 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3231 Handle thread_group = create_initial_thread_group(CHECK);
3232 Universe::set_main_thread_group(thread_group());
3233 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3234 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3235 main_thread->set_threadObj(thread_object);
3236 // Set thread status to running since main thread has
3237 // been started and running.
3238 java_lang_Thread::set_thread_status(thread_object,
3239 java_lang_Thread::RUNNABLE);
3240
3241 // The VM creates & returns objects of this class. Make sure it's initialized.
3242 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3243
3244 // The VM preresolves methods to these classes. Make sure that they get initialized
3245 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3246 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3247 call_initializeSystemClass(CHECK);
3248
3249 // get the Java runtime name after java.lang.System is initialized
3250 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3251 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3252
3253 // an instance of OutOfMemory exception has been allocated earlier
3254 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3255 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3256 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3257 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3258 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3259 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3260 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3261 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3262 }
3263
3264 void Threads::initialize_jsr292_core_classes(TRAPS) {
3265 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3266 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3267 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3268 }
3269
3270 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3271 extern void JDK_Version_init();
3272
3273 // Check version
3274 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3275
3276 // Initialize the output stream module
3277 ostream_init();
3278
3279 // Process java launcher properties.
3280 Arguments::process_sun_java_launcher_properties(args);
3281
3282 // Initialize the os module before using TLS
3283 os::init();
3284
3285 // Initialize system properties.
3286 Arguments::init_system_properties();
3287
3288 // So that JDK version can be used as a discriminator when parsing arguments
3289 JDK_Version_init();
3290
3291 // Update/Initialize System properties after JDK version number is known
3292 Arguments::init_version_specific_system_properties();
3293
3294 // Parse arguments
3295 jint parse_result = Arguments::parse(args);
3296 if (parse_result != JNI_OK) return parse_result;
3297
3298 os::init_before_ergo();
3299
3300 jint ergo_result = Arguments::apply_ergo();
3301 if (ergo_result != JNI_OK) return ergo_result;
3302
3303 if (PauseAtStartup) {
3304 os::pause();
3305 }
3306
3307 HOTSPOT_VM_INIT_BEGIN();
3308
3309 // Record VM creation timing statistics
3310 TraceVmCreationTime create_vm_timer;
3311 create_vm_timer.start();
3312
3313 // Timing (must come after argument parsing)
3314 TraceTime timer("Create VM", TraceStartupTime);
3315
3316 // Initialize the os module after parsing the args
3317 jint os_init_2_result = os::init_2();
3318 if (os_init_2_result != JNI_OK) return os_init_2_result;
3319
3320 jint adjust_after_os_result = Arguments::adjust_after_os();
3321 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3322
3323 // initialize TLS
3324 ThreadLocalStorage::init();
3325
3326 // Initialize output stream logging
3327 ostream_init_log();
3328
3329 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3330 // Must be before create_vm_init_agents()
3331 if (Arguments::init_libraries_at_startup()) {
3332 convert_vm_init_libraries_to_agents();
3333 }
3334
3335 // Launch -agentlib/-agentpath and converted -Xrun agents
3336 if (Arguments::init_agents_at_startup()) {
3337 create_vm_init_agents();
3338 }
3339
3340 // Initialize Threads state
3341 _thread_list = NULL;
3342 _number_of_threads = 0;
3343 _number_of_non_daemon_threads = 0;
3344
3345 // Initialize global data structures and create system classes in heap
3346 vm_init_globals();
3347
3348 // Attach the main thread to this os thread
3349 JavaThread* main_thread = new JavaThread();
3350 main_thread->set_thread_state(_thread_in_vm);
3351 // must do this before set_active_handles and initialize_thread_local_storage
3352 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3353 // change the stack size recorded here to one based on the java thread
3354 // stacksize. This adjusted size is what is used to figure the placement
3355 // of the guard pages.
3356 main_thread->record_stack_base_and_size();
3357 main_thread->initialize_thread_local_storage();
3358
3359 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3360
3361 if (!main_thread->set_as_starting_thread()) {
3362 vm_shutdown_during_initialization(
3363 "Failed necessary internal allocation. Out of swap space");
3364 delete main_thread;
3365 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3366 return JNI_ENOMEM;
3367 }
3368
3369 // Enable guard page *after* os::create_main_thread(), otherwise it would
3370 // crash Linux VM, see notes in os_linux.cpp.
3371 main_thread->create_stack_guard_pages();
3372
3373 // Initialize Java-Level synchronization subsystem
3374 ObjectMonitor::Initialize();
3375
3376 // Initialize global modules
3377 jint status = init_globals();
3378 if (status != JNI_OK) {
3379 delete main_thread;
3380 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3381 return status;
3382 }
3383
3384 // Should be done after the heap is fully created
3385 main_thread->cache_global_variables();
3386
3387 HandleMark hm;
3388
3389 { MutexLocker mu(Threads_lock);
3390 Threads::add(main_thread);
3391 }
3392
3393 // Any JVMTI raw monitors entered in onload will transition into
3394 // real raw monitor. VM is setup enough here for raw monitor enter.
3395 JvmtiExport::transition_pending_onload_raw_monitors();
3396
3397 // Create the VMThread
3398 { TraceTime timer("Start VMThread", TraceStartupTime);
3399 VMThread::create();
3400 Thread* vmthread = VMThread::vm_thread();
3401
3402 if (!os::create_thread(vmthread, os::vm_thread)) {
3403 vm_exit_during_initialization("Cannot create VM thread. "
3404 "Out of system resources.");
3405 }
3406
3407 // Wait for the VM thread to become ready, and VMThread::run to initialize
3408 // Monitors can have spurious returns, must always check another state flag
3409 {
3410 MutexLocker ml(Notify_lock);
3411 os::start_thread(vmthread);
3412 while (vmthread->active_handles() == NULL) {
3413 Notify_lock->wait();
3414 }
3415 }
3416 }
3417
3418 assert(Universe::is_fully_initialized(), "not initialized");
3419 if (VerifyDuringStartup) {
3420 // Make sure we're starting with a clean slate.
3421 VM_Verify verify_op;
3422 VMThread::execute(&verify_op);
3423 }
3424
3425 Thread* THREAD = Thread::current();
3426
3427 // At this point, the Universe is initialized, but we have not executed
3428 // any byte code. Now is a good time (the only time) to dump out the
3429 // internal state of the JVM for sharing.
3430 if (DumpSharedSpaces) {
3431 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3432 ShouldNotReachHere();
3433 }
3434
3435 // Always call even when there are not JVMTI environments yet, since environments
3436 // may be attached late and JVMTI must track phases of VM execution
3437 JvmtiExport::enter_start_phase();
3438
3439 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3440 JvmtiExport::post_vm_start();
3441
3442 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3443
3444 // We need this for ClassDataSharing - the initial vm.info property is set
3445 // with the default value of CDS "sharing" which may be reset through
3446 // command line options.
3447 reset_vm_info_property(CHECK_JNI_ERR);
3448
3449 quicken_jni_functions();
3450
3451 // Must be run after init_ft which initializes ft_enabled
3452 if (TRACE_INITIALIZE() != JNI_OK) {
3453 vm_exit_during_initialization("Failed to initialize tracing backend");
3454 }
3455
3456 // Set flag that basic initialization has completed. Used by exceptions and various
3457 // debug stuff, that does not work until all basic classes have been initialized.
3458 set_init_completed();
3459
3460 Metaspace::post_initialize();
3461
3462 HOTSPOT_VM_INIT_END();
3463
3464 // record VM initialization completion time
3465 #if INCLUDE_MANAGEMENT
3466 Management::record_vm_init_completed();
3467 #endif // INCLUDE_MANAGEMENT
3468
3469 // Compute system loader. Note that this has to occur after set_init_completed, since
3470 // valid exceptions may be thrown in the process.
3471 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3472 // set_init_completed has just been called, causing exceptions not to be shortcut
3473 // anymore. We call vm_exit_during_initialization directly instead.
3474 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3475
3476 #if INCLUDE_ALL_GCS
3477 // Support for ConcurrentMarkSweep. This should be cleaned up
3478 // and better encapsulated. The ugly nested if test would go away
3479 // once things are properly refactored. XXX YSR
3480 if (UseConcMarkSweepGC || UseG1GC) {
3481 if (UseConcMarkSweepGC) {
3482 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3483 } else {
3484 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3485 }
3486 }
3487 #endif // INCLUDE_ALL_GCS
3488
3489 // Always call even when there are not JVMTI environments yet, since environments
3490 // may be attached late and JVMTI must track phases of VM execution
3491 JvmtiExport::enter_live_phase();
3492
3493 // Signal Dispatcher needs to be started before VMInit event is posted
3494 os::signal_init();
3495
3496 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3497 if (!DisableAttachMechanism) {
3498 AttachListener::vm_start();
3499 if (StartAttachListener || AttachListener::init_at_startup()) {
3500 AttachListener::init();
3501 }
3502 }
3503
3504 // Launch -Xrun agents
3505 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3506 // back-end can launch with -Xdebug -Xrunjdwp.
3507 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3508 create_vm_init_libraries();
3509 }
3510
3511 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3512 JvmtiExport::post_vm_initialized();
3513
3514 if (TRACE_START() != JNI_OK) {
3515 vm_exit_during_initialization("Failed to start tracing backend.");
3516 }
3517
3518 if (CleanChunkPoolAsync) {
3519 Chunk::start_chunk_pool_cleaner_task();
3520 }
3521
3522 // initialize compiler(s)
3523 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3524 CompileBroker::compilation_init();
3525 #endif
3526
3527 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3528 // It is done after compilers are initialized, because otherwise compilations of
3529 // signature polymorphic MH intrinsics can be missed
3530 // (see SystemDictionary::find_method_handle_intrinsic).
3531 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3532
3533 #if INCLUDE_MANAGEMENT
3534 Management::initialize(THREAD);
3535
3536 if (HAS_PENDING_EXCEPTION) {
3537 // management agent fails to start possibly due to
3538 // configuration problem and is responsible for printing
3539 // stack trace if appropriate. Simply exit VM.
3540 vm_exit(1);
3541 }
3542 #endif // INCLUDE_MANAGEMENT
3543
3544 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3545 if (MemProfiling) MemProfiler::engage();
3546 StatSampler::engage();
3547 if (CheckJNICalls) JniPeriodicChecker::engage();
3548
3549 BiasedLocking::init();
3550
3551 #if INCLUDE_RTM_OPT
3552 RTMLockingCounters::init();
3553 #endif
3554
3555 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3556 call_postVMInitHook(THREAD);
3557 // The Java side of PostVMInitHook.run must deal with all
3558 // exceptions and provide means of diagnosis.
3559 if (HAS_PENDING_EXCEPTION) {
3560 CLEAR_PENDING_EXCEPTION;
3561 }
3562 }
3563
3564 {
3565 MutexLocker ml(PeriodicTask_lock);
3566 // Make sure the WatcherThread can be started by WatcherThread::start()
3567 // or by dynamic enrollment.
3568 WatcherThread::make_startable();
3569 // Start up the WatcherThread if there are any periodic tasks
3570 // NOTE: All PeriodicTasks should be registered by now. If they
3571 // aren't, late joiners might appear to start slowly (we might
3572 // take a while to process their first tick).
3573 if (PeriodicTask::num_tasks() > 0) {
3574 WatcherThread::start();
3575 }
3576 }
3577
3578 create_vm_timer.end();
3579 #ifdef ASSERT
3580 _vm_complete = true;
3581 #endif
3582 return JNI_OK;
3583 }
3584
3585 // type for the Agent_OnLoad and JVM_OnLoad entry points
3586 extern "C" {
3587 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3588 }
3589 // Find a command line agent library and return its entry point for
3590 // -agentlib: -agentpath: -Xrun
3591 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3592 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3593 const char *on_load_symbols[],
3594 size_t num_symbol_entries) {
3595 OnLoadEntry_t on_load_entry = NULL;
3596 void *library = NULL;
3597
3598 if (!agent->valid()) {
3599 char buffer[JVM_MAXPATHLEN];
3600 char ebuf[1024] = "";
3601 const char *name = agent->name();
3602 const char *msg = "Could not find agent library ";
3603
3604 // First check to see if agent is statically linked into executable
3605 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3606 library = agent->os_lib();
3607 } else if (agent->is_absolute_path()) {
3608 library = os::dll_load(name, ebuf, sizeof ebuf);
3609 if (library == NULL) {
3610 const char *sub_msg = " in absolute path, with error: ";
3611 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3612 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3613 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3614 // If we can't find the agent, exit.
3615 vm_exit_during_initialization(buf, NULL);
3616 FREE_C_HEAP_ARRAY(char, buf);
3617 }
3618 } else {
3619 // Try to load the agent from the standard dll directory
3620 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3621 name)) {
3622 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3623 }
3624 if (library == NULL) { // Try the local directory
3625 char ns[1] = {0};
3626 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3627 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3628 }
3629 if (library == NULL) {
3630 const char *sub_msg = " on the library path, with error: ";
3631 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3632 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3633 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3634 // If we can't find the agent, exit.
3635 vm_exit_during_initialization(buf, NULL);
3636 FREE_C_HEAP_ARRAY(char, buf);
3637 }
3638 }
3639 }
3640 agent->set_os_lib(library);
3641 agent->set_valid();
3642 }
3643
3644 // Find the OnLoad function.
3645 on_load_entry =
3646 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3647 false,
3648 on_load_symbols,
3649 num_symbol_entries));
3650 return on_load_entry;
3651 }
3652
3653 // Find the JVM_OnLoad entry point
3654 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3655 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3656 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3657 }
3658
3659 // Find the Agent_OnLoad entry point
3660 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3661 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3662 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3663 }
3664
3665 // For backwards compatibility with -Xrun
3666 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3667 // treated like -agentpath:
3668 // Must be called before agent libraries are created
3669 void Threads::convert_vm_init_libraries_to_agents() {
3670 AgentLibrary* agent;
3671 AgentLibrary* next;
3672
3673 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3674 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3675 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3676
3677 // If there is an JVM_OnLoad function it will get called later,
3678 // otherwise see if there is an Agent_OnLoad
3679 if (on_load_entry == NULL) {
3680 on_load_entry = lookup_agent_on_load(agent);
3681 if (on_load_entry != NULL) {
3682 // switch it to the agent list -- so that Agent_OnLoad will be called,
3683 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3684 Arguments::convert_library_to_agent(agent);
3685 } else {
3686 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3687 }
3688 }
3689 }
3690 }
3691
3692 // Create agents for -agentlib: -agentpath: and converted -Xrun
3693 // Invokes Agent_OnLoad
3694 // Called very early -- before JavaThreads exist
3695 void Threads::create_vm_init_agents() {
3696 extern struct JavaVM_ main_vm;
3697 AgentLibrary* agent;
3698
3699 JvmtiExport::enter_onload_phase();
3700
3701 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3702 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3703
3704 if (on_load_entry != NULL) {
3705 // Invoke the Agent_OnLoad function
3706 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3707 if (err != JNI_OK) {
3708 vm_exit_during_initialization("agent library failed to init", agent->name());
3709 }
3710 } else {
3711 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3712 }
3713 }
3714 JvmtiExport::enter_primordial_phase();
3715 }
3716
3717 extern "C" {
3718 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3719 }
3720
3721 void Threads::shutdown_vm_agents() {
3722 // Send any Agent_OnUnload notifications
3723 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3724 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3725 extern struct JavaVM_ main_vm;
3726 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3727
3728 // Find the Agent_OnUnload function.
3729 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3730 os::find_agent_function(agent,
3731 false,
3732 on_unload_symbols,
3733 num_symbol_entries));
3734
3735 // Invoke the Agent_OnUnload function
3736 if (unload_entry != NULL) {
3737 JavaThread* thread = JavaThread::current();
3738 ThreadToNativeFromVM ttn(thread);
3739 HandleMark hm(thread);
3740 (*unload_entry)(&main_vm);
3741 }
3742 }
3743 }
3744
3745 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3746 // Invokes JVM_OnLoad
3747 void Threads::create_vm_init_libraries() {
3748 extern struct JavaVM_ main_vm;
3749 AgentLibrary* agent;
3750
3751 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3752 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3753
3754 if (on_load_entry != NULL) {
3755 // Invoke the JVM_OnLoad function
3756 JavaThread* thread = JavaThread::current();
3757 ThreadToNativeFromVM ttn(thread);
3758 HandleMark hm(thread);
3759 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3760 if (err != JNI_OK) {
3761 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3762 }
3763 } else {
3764 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3765 }
3766 }
3767 }
3768
3769 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3770 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3771
3772 JavaThread* java_thread = NULL;
3773 // Sequential search for now. Need to do better optimization later.
3774 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3775 oop tobj = thread->threadObj();
3776 if (!thread->is_exiting() &&
3777 tobj != NULL &&
3778 java_tid == java_lang_Thread::thread_id(tobj)) {
3779 java_thread = thread;
3780 break;
3781 }
3782 }
3783 return java_thread;
3784 }
3785
3786
3787 // Last thread running calls java.lang.Shutdown.shutdown()
3788 void JavaThread::invoke_shutdown_hooks() {
3789 HandleMark hm(this);
3790
3791 // We could get here with a pending exception, if so clear it now.
3792 if (this->has_pending_exception()) {
3793 this->clear_pending_exception();
3794 }
3795
3796 EXCEPTION_MARK;
3797 Klass* k =
3798 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3799 THREAD);
3800 if (k != NULL) {
3801 // SystemDictionary::resolve_or_null will return null if there was
3802 // an exception. If we cannot load the Shutdown class, just don't
3803 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3804 // and finalizers (if runFinalizersOnExit is set) won't be run.
3805 // Note that if a shutdown hook was registered or runFinalizersOnExit
3806 // was called, the Shutdown class would have already been loaded
3807 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3808 instanceKlassHandle shutdown_klass (THREAD, k);
3809 JavaValue result(T_VOID);
3810 JavaCalls::call_static(&result,
3811 shutdown_klass,
3812 vmSymbols::shutdown_method_name(),
3813 vmSymbols::void_method_signature(),
3814 THREAD);
3815 }
3816 CLEAR_PENDING_EXCEPTION;
3817 }
3818
3819 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3820 // the program falls off the end of main(). Another VM exit path is through
3821 // vm_exit() when the program calls System.exit() to return a value or when
3822 // there is a serious error in VM. The two shutdown paths are not exactly
3823 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3824 // and VM_Exit op at VM level.
3825 //
3826 // Shutdown sequence:
3827 // + Shutdown native memory tracking if it is on
3828 // + Wait until we are the last non-daemon thread to execute
3829 // <-- every thing is still working at this moment -->
3830 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3831 // shutdown hooks, run finalizers if finalization-on-exit
3832 // + Call before_exit(), prepare for VM exit
3833 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3834 // currently the only user of this mechanism is File.deleteOnExit())
3835 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3836 // post thread end and vm death events to JVMTI,
3837 // stop signal thread
3838 // + Call JavaThread::exit(), it will:
3839 // > release JNI handle blocks, remove stack guard pages
3840 // > remove this thread from Threads list
3841 // <-- no more Java code from this thread after this point -->
3842 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3843 // the compiler threads at safepoint
3844 // <-- do not use anything that could get blocked by Safepoint -->
3845 // + Disable tracing at JNI/JVM barriers
3846 // + Set _vm_exited flag for threads that are still running native code
3847 // + Delete this thread
3848 // + Call exit_globals()
3849 // > deletes tty
3850 // > deletes PerfMemory resources
3851 // + Return to caller
3852
3853 bool Threads::destroy_vm() {
3854 JavaThread* thread = JavaThread::current();
3855
3856 #ifdef ASSERT
3857 _vm_complete = false;
3858 #endif
3859 // Wait until we are the last non-daemon thread to execute
3860 { MutexLocker nu(Threads_lock);
3861 while (Threads::number_of_non_daemon_threads() > 1)
3862 // This wait should make safepoint checks, wait without a timeout,
3863 // and wait as a suspend-equivalent condition.
3864 //
3865 // Note: If the FlatProfiler is running and this thread is waiting
3866 // for another non-daemon thread to finish, then the FlatProfiler
3867 // is waiting for the external suspend request on this thread to
3868 // complete. wait_for_ext_suspend_completion() will eventually
3869 // timeout, but that takes time. Making this wait a suspend-
3870 // equivalent condition solves that timeout problem.
3871 //
3872 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3873 Mutex::_as_suspend_equivalent_flag);
3874 }
3875
3876 // Hang forever on exit if we are reporting an error.
3877 if (ShowMessageBoxOnError && is_error_reported()) {
3878 os::infinite_sleep();
3879 }
3880 os::wait_for_keypress_at_exit();
3881
3882 // run Java level shutdown hooks
3883 thread->invoke_shutdown_hooks();
3884
3885 before_exit(thread);
3886
3887 thread->exit(true);
3888
3889 // Stop VM thread.
3890 {
3891 // 4945125 The vm thread comes to a safepoint during exit.
3892 // GC vm_operations can get caught at the safepoint, and the
3893 // heap is unparseable if they are caught. Grab the Heap_lock
3894 // to prevent this. The GC vm_operations will not be able to
3895 // queue until after the vm thread is dead. After this point,
3896 // we'll never emerge out of the safepoint before the VM exits.
3897
3898 MutexLocker ml(Heap_lock);
3899
3900 VMThread::wait_for_vm_thread_exit();
3901 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3902 VMThread::destroy();
3903 }
3904
3905 // clean up ideal graph printers
3906 #if defined(COMPILER2) && !defined(PRODUCT)
3907 IdealGraphPrinter::clean_up();
3908 #endif
3909
3910 // Now, all Java threads are gone except daemon threads. Daemon threads
3911 // running Java code or in VM are stopped by the Safepoint. However,
3912 // daemon threads executing native code are still running. But they
3913 // will be stopped at native=>Java/VM barriers. Note that we can't
3914 // simply kill or suspend them, as it is inherently deadlock-prone.
3915
3916 #ifndef PRODUCT
3917 // disable function tracing at JNI/JVM barriers
3918 TraceJNICalls = false;
3919 TraceJVMCalls = false;
3920 TraceRuntimeCalls = false;
3921 #endif
3922
3923 VM_Exit::set_vm_exited();
3924
3925 notify_vm_shutdown();
3926
3927 delete thread;
3928
3929 // exit_globals() will delete tty
3930 exit_globals();
3931
3932 return true;
3933 }
3934
3935
3936 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3937 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3938 return is_supported_jni_version(version);
3939 }
3940
3941
3942 jboolean Threads::is_supported_jni_version(jint version) {
3943 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3944 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3945 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3946 if (version == JNI_VERSION_1_8) return JNI_TRUE;
3947 return JNI_FALSE;
3948 }
3949
3950
3951 void Threads::add(JavaThread* p, bool force_daemon) {
3952 // The threads lock must be owned at this point
3953 assert_locked_or_safepoint(Threads_lock);
3954
3955 // See the comment for this method in thread.hpp for its purpose and
3956 // why it is called here.
3957 p->initialize_queues();
3958 p->set_next(_thread_list);
3959 _thread_list = p;
3960 _number_of_threads++;
3961 oop threadObj = p->threadObj();
3962 bool daemon = true;
3963 // Bootstrapping problem: threadObj can be null for initial
3964 // JavaThread (or for threads attached via JNI)
3965 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3966 _number_of_non_daemon_threads++;
3967 daemon = false;
3968 }
3969
3970 ThreadService::add_thread(p, daemon);
3971
3972 // Possible GC point.
3973 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3974 }
3975
3976 void Threads::remove(JavaThread* p) {
3977 // Extra scope needed for Thread_lock, so we can check
3978 // that we do not remove thread without safepoint code notice
3979 { MutexLocker ml(Threads_lock);
3980
3981 assert(includes(p), "p must be present");
3982
3983 JavaThread* current = _thread_list;
3984 JavaThread* prev = NULL;
3985
3986 while (current != p) {
3987 prev = current;
3988 current = current->next();
3989 }
3990
3991 if (prev) {
3992 prev->set_next(current->next());
3993 } else {
3994 _thread_list = p->next();
3995 }
3996 _number_of_threads--;
3997 oop threadObj = p->threadObj();
3998 bool daemon = true;
3999 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4000 _number_of_non_daemon_threads--;
4001 daemon = false;
4002
4003 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4004 // on destroy_vm will wake up.
4005 if (number_of_non_daemon_threads() == 1) {
4006 Threads_lock->notify_all();
4007 }
4008 }
4009 ThreadService::remove_thread(p, daemon);
4010
4011 // Make sure that safepoint code disregard this thread. This is needed since
4012 // the thread might mess around with locks after this point. This can cause it
4013 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4014 // of this thread since it is removed from the queue.
4015 p->set_terminated_value();
4016 } // unlock Threads_lock
4017
4018 // Since Events::log uses a lock, we grab it outside the Threads_lock
4019 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4020 }
4021
4022 // Threads_lock must be held when this is called (or must be called during a safepoint)
4023 bool Threads::includes(JavaThread* p) {
4024 assert(Threads_lock->is_locked(), "sanity check");
4025 ALL_JAVA_THREADS(q) {
4026 if (q == p) {
4027 return true;
4028 }
4029 }
4030 return false;
4031 }
4032
4033 // Operations on the Threads list for GC. These are not explicitly locked,
4034 // but the garbage collector must provide a safe context for them to run.
4035 // In particular, these things should never be called when the Threads_lock
4036 // is held by some other thread. (Note: the Safepoint abstraction also
4037 // uses the Threads_lock to guarantee this property. It also makes sure that
4038 // all threads gets blocked when exiting or starting).
4039
4040 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4041 ALL_JAVA_THREADS(p) {
4042 p->oops_do(f, cld_f, cf);
4043 }
4044 VMThread::vm_thread()->oops_do(f, cld_f, cf);
4045 }
4046
4047 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4048 // Introduce a mechanism allowing parallel threads to claim threads as
4049 // root groups. Overhead should be small enough to use all the time,
4050 // even in sequential code.
4051 SharedHeap* sh = SharedHeap::heap();
4052 // Cannot yet substitute active_workers for n_par_threads
4053 // because of G1CollectedHeap::verify() use of
4054 // SharedHeap::process_roots(). n_par_threads == 0 will
4055 // turn off parallelism in process_roots while active_workers
4056 // is being used for parallelism elsewhere.
4057 bool is_par = sh->n_par_threads() > 0;
4058 assert(!is_par ||
4059 (SharedHeap::heap()->n_par_threads() ==
4060 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4061 int cp = SharedHeap::heap()->strong_roots_parity();
4062 ALL_JAVA_THREADS(p) {
4063 if (p->claim_oops_do(is_par, cp)) {
4064 p->oops_do(f, cld_f, cf);
4065 }
4066 }
4067 VMThread* vmt = VMThread::vm_thread();
4068 if (vmt->claim_oops_do(is_par, cp)) {
4069 vmt->oops_do(f, cld_f, cf);
4070 }
4071 }
4072
4073 #if INCLUDE_ALL_GCS
4074 // Used by ParallelScavenge
4075 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4076 ALL_JAVA_THREADS(p) {
4077 q->enqueue(new ThreadRootsTask(p));
4078 }
4079 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4080 }
4081
4082 // Used by Parallel Old
4083 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4084 ALL_JAVA_THREADS(p) {
4085 q->enqueue(new ThreadRootsMarkingTask(p));
4086 }
4087 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4088 }
4089 #endif // INCLUDE_ALL_GCS
4090
4091 void Threads::nmethods_do(CodeBlobClosure* cf) {
4092 ALL_JAVA_THREADS(p) {
4093 p->nmethods_do(cf);
4094 }
4095 VMThread::vm_thread()->nmethods_do(cf);
4096 }
4097
4098 void Threads::metadata_do(void f(Metadata*)) {
4099 ALL_JAVA_THREADS(p) {
4100 p->metadata_do(f);
4101 }
4102 }
4103
4104 void Threads::deoptimized_wrt_marked_nmethods() {
4105 ALL_JAVA_THREADS(p) {
4106 p->deoptimized_wrt_marked_nmethods();
4107 }
4108 }
4109
4110
4111 // Get count Java threads that are waiting to enter the specified monitor.
4112 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4113 address monitor,
4114 bool doLock) {
4115 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4116 "must grab Threads_lock or be at safepoint");
4117 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4118
4119 int i = 0;
4120 {
4121 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4122 ALL_JAVA_THREADS(p) {
4123 if (p->is_Compiler_thread()) continue;
4124
4125 address pending = (address)p->current_pending_monitor();
4126 if (pending == monitor) { // found a match
4127 if (i < count) result->append(p); // save the first count matches
4128 i++;
4129 }
4130 }
4131 }
4132 return result;
4133 }
4134
4135
4136 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4137 bool doLock) {
4138 assert(doLock ||
4139 Threads_lock->owned_by_self() ||
4140 SafepointSynchronize::is_at_safepoint(),
4141 "must grab Threads_lock or be at safepoint");
4142
4143 // NULL owner means not locked so we can skip the search
4144 if (owner == NULL) return NULL;
4145
4146 {
4147 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4148 ALL_JAVA_THREADS(p) {
4149 // first, see if owner is the address of a Java thread
4150 if (owner == (address)p) return p;
4151 }
4152 }
4153 // Cannot assert on lack of success here since this function may be
4154 // used by code that is trying to report useful problem information
4155 // like deadlock detection.
4156 if (UseHeavyMonitors) return NULL;
4157
4158 // If we didn't find a matching Java thread and we didn't force use of
4159 // heavyweight monitors, then the owner is the stack address of the
4160 // Lock Word in the owning Java thread's stack.
4161 //
4162 JavaThread* the_owner = NULL;
4163 {
4164 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4165 ALL_JAVA_THREADS(q) {
4166 if (q->is_lock_owned(owner)) {
4167 the_owner = q;
4168 break;
4169 }
4170 }
4171 }
4172 // cannot assert on lack of success here; see above comment
4173 return the_owner;
4174 }
4175
4176 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4177 void Threads::print_on(outputStream* st, bool print_stacks,
4178 bool internal_format, bool print_concurrent_locks) {
4179 char buf[32];
4180 st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4181
4182 st->print_cr("Full thread dump %s (%s %s):",
4183 Abstract_VM_Version::vm_name(),
4184 Abstract_VM_Version::vm_release(),
4185 Abstract_VM_Version::vm_info_string());
4186 st->cr();
4187
4188 #if INCLUDE_ALL_GCS
4189 // Dump concurrent locks
4190 ConcurrentLocksDump concurrent_locks;
4191 if (print_concurrent_locks) {
4192 concurrent_locks.dump_at_safepoint();
4193 }
4194 #endif // INCLUDE_ALL_GCS
4195
4196 ALL_JAVA_THREADS(p) {
4197 ResourceMark rm;
4198 p->print_on(st);
4199 if (print_stacks) {
4200 if (internal_format) {
4201 p->trace_stack();
4202 } else {
4203 p->print_stack_on(st);
4204 }
4205 }
4206 st->cr();
4207 #if INCLUDE_ALL_GCS
4208 if (print_concurrent_locks) {
4209 concurrent_locks.print_locks_on(p, st);
4210 }
4211 #endif // INCLUDE_ALL_GCS
4212 }
4213
4214 VMThread::vm_thread()->print_on(st);
4215 st->cr();
4216 Universe::heap()->print_gc_threads_on(st);
4217 WatcherThread* wt = WatcherThread::watcher_thread();
4218 if (wt != NULL) {
4219 wt->print_on(st);
4220 st->cr();
4221 }
4222 CompileBroker::print_compiler_threads_on(st);
4223 st->flush();
4224 }
4225
4226 // Threads::print_on_error() is called by fatal error handler. It's possible
4227 // that VM is not at safepoint and/or current thread is inside signal handler.
4228 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4229 // memory (even in resource area), it might deadlock the error handler.
4230 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4231 int buflen) {
4232 bool found_current = false;
4233 st->print_cr("Java Threads: ( => current thread )");
4234 ALL_JAVA_THREADS(thread) {
4235 bool is_current = (current == thread);
4236 found_current = found_current || is_current;
4237
4238 st->print("%s", is_current ? "=>" : " ");
4239
4240 st->print(PTR_FORMAT, thread);
4241 st->print(" ");
4242 thread->print_on_error(st, buf, buflen);
4243 st->cr();
4244 }
4245 st->cr();
4246
4247 st->print_cr("Other Threads:");
4248 if (VMThread::vm_thread()) {
4249 bool is_current = (current == VMThread::vm_thread());
4250 found_current = found_current || is_current;
4251 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4252
4253 st->print(PTR_FORMAT, VMThread::vm_thread());
4254 st->print(" ");
4255 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4256 st->cr();
4257 }
4258 WatcherThread* wt = WatcherThread::watcher_thread();
4259 if (wt != NULL) {
4260 bool is_current = (current == wt);
4261 found_current = found_current || is_current;
4262 st->print("%s", is_current ? "=>" : " ");
4263
4264 st->print(PTR_FORMAT, wt);
4265 st->print(" ");
4266 wt->print_on_error(st, buf, buflen);
4267 st->cr();
4268 }
4269 if (!found_current) {
4270 st->cr();
4271 st->print("=>" PTR_FORMAT " (exited) ", current);
4272 current->print_on_error(st, buf, buflen);
4273 st->cr();
4274 }
4275 }
4276
4277 // Internal SpinLock and Mutex
4278 // Based on ParkEvent
4279
4280 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4281 //
4282 // We employ SpinLocks _only for low-contention, fixed-length
4283 // short-duration critical sections where we're concerned
4284 // about native mutex_t or HotSpot Mutex:: latency.
4285 // The mux construct provides a spin-then-block mutual exclusion
4286 // mechanism.
4287 //
4288 // Testing has shown that contention on the ListLock guarding gFreeList
4289 // is common. If we implement ListLock as a simple SpinLock it's common
4290 // for the JVM to devolve to yielding with little progress. This is true
4291 // despite the fact that the critical sections protected by ListLock are
4292 // extremely short.
4293 //
4294 // TODO-FIXME: ListLock should be of type SpinLock.
4295 // We should make this a 1st-class type, integrated into the lock
4296 // hierarchy as leaf-locks. Critically, the SpinLock structure
4297 // should have sufficient padding to avoid false-sharing and excessive
4298 // cache-coherency traffic.
4299
4300
4301 typedef volatile int SpinLockT;
4302
4303 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4304 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4305 return; // normal fast-path return
4306 }
4307
4308 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4309 TEVENT(SpinAcquire - ctx);
4310 int ctr = 0;
4311 int Yields = 0;
4312 for (;;) {
4313 while (*adr != 0) {
4314 ++ctr;
4315 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4316 if (Yields > 5) {
4317 os::naked_short_sleep(1);
4318 } else {
4319 os::naked_yield();
4320 ++Yields;
4321 }
4322 } else {
4323 SpinPause();
4324 }
4325 }
4326 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4327 }
4328 }
4329
4330 void Thread::SpinRelease(volatile int * adr) {
4331 assert(*adr != 0, "invariant");
4332 OrderAccess::fence(); // guarantee at least release consistency.
4333 // Roach-motel semantics.
4334 // It's safe if subsequent LDs and STs float "up" into the critical section,
4335 // but prior LDs and STs within the critical section can't be allowed
4336 // to reorder or float past the ST that releases the lock.
4337 // Loads and stores in the critical section - which appear in program
4338 // order before the store that releases the lock - must also appear
4339 // before the store that releases the lock in memory visibility order.
4340 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4341 // the ST of 0 into the lock-word which releases the lock, so fence
4342 // more than covers this on all platforms.
4343 *adr = 0;
4344 }
4345
4346 // muxAcquire and muxRelease:
4347 //
4348 // * muxAcquire and muxRelease support a single-word lock-word construct.
4349 // The LSB of the word is set IFF the lock is held.
4350 // The remainder of the word points to the head of a singly-linked list
4351 // of threads blocked on the lock.
4352 //
4353 // * The current implementation of muxAcquire-muxRelease uses its own
4354 // dedicated Thread._MuxEvent instance. If we're interested in
4355 // minimizing the peak number of extant ParkEvent instances then
4356 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4357 // as certain invariants were satisfied. Specifically, care would need
4358 // to be taken with regards to consuming unpark() "permits".
4359 // A safe rule of thumb is that a thread would never call muxAcquire()
4360 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4361 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4362 // consume an unpark() permit intended for monitorenter, for instance.
4363 // One way around this would be to widen the restricted-range semaphore
4364 // implemented in park(). Another alternative would be to provide
4365 // multiple instances of the PlatformEvent() for each thread. One
4366 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4367 //
4368 // * Usage:
4369 // -- Only as leaf locks
4370 // -- for short-term locking only as muxAcquire does not perform
4371 // thread state transitions.
4372 //
4373 // Alternatives:
4374 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4375 // but with parking or spin-then-park instead of pure spinning.
4376 // * Use Taura-Oyama-Yonenzawa locks.
4377 // * It's possible to construct a 1-0 lock if we encode the lockword as
4378 // (List,LockByte). Acquire will CAS the full lockword while Release
4379 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4380 // acquiring threads use timers (ParkTimed) to detect and recover from
4381 // the stranding window. Thread/Node structures must be aligned on 256-byte
4382 // boundaries by using placement-new.
4383 // * Augment MCS with advisory back-link fields maintained with CAS().
4384 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4385 // The validity of the backlinks must be ratified before we trust the value.
4386 // If the backlinks are invalid the exiting thread must back-track through the
4387 // the forward links, which are always trustworthy.
4388 // * Add a successor indication. The LockWord is currently encoded as
4389 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4390 // to provide the usual futile-wakeup optimization.
4391 // See RTStt for details.
4392 // * Consider schedctl.sc_nopreempt to cover the critical section.
4393 //
4394
4395
4396 typedef volatile intptr_t MutexT; // Mux Lock-word
4397 enum MuxBits { LOCKBIT = 1 };
4398
4399 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4400 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4401 if (w == 0) return;
4402 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4403 return;
4404 }
4405
4406 TEVENT(muxAcquire - Contention);
4407 ParkEvent * const Self = Thread::current()->_MuxEvent;
4408 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4409 for (;;) {
4410 int its = (os::is_MP() ? 100 : 0) + 1;
4411
4412 // Optional spin phase: spin-then-park strategy
4413 while (--its >= 0) {
4414 w = *Lock;
4415 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4416 return;
4417 }
4418 }
4419
4420 Self->reset();
4421 Self->OnList = intptr_t(Lock);
4422 // The following fence() isn't _strictly necessary as the subsequent
4423 // CAS() both serializes execution and ratifies the fetched *Lock value.
4424 OrderAccess::fence();
4425 for (;;) {
4426 w = *Lock;
4427 if ((w & LOCKBIT) == 0) {
4428 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4429 Self->OnList = 0; // hygiene - allows stronger asserts
4430 return;
4431 }
4432 continue; // Interference -- *Lock changed -- Just retry
4433 }
4434 assert(w & LOCKBIT, "invariant");
4435 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4436 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4437 }
4438
4439 while (Self->OnList != 0) {
4440 Self->park();
4441 }
4442 }
4443 }
4444
4445 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4446 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4447 if (w == 0) return;
4448 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4449 return;
4450 }
4451
4452 TEVENT(muxAcquire - Contention);
4453 ParkEvent * ReleaseAfter = NULL;
4454 if (ev == NULL) {
4455 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4456 }
4457 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4458 for (;;) {
4459 guarantee(ev->OnList == 0, "invariant");
4460 int its = (os::is_MP() ? 100 : 0) + 1;
4461
4462 // Optional spin phase: spin-then-park strategy
4463 while (--its >= 0) {
4464 w = *Lock;
4465 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4466 if (ReleaseAfter != NULL) {
4467 ParkEvent::Release(ReleaseAfter);
4468 }
4469 return;
4470 }
4471 }
4472
4473 ev->reset();
4474 ev->OnList = intptr_t(Lock);
4475 // The following fence() isn't _strictly necessary as the subsequent
4476 // CAS() both serializes execution and ratifies the fetched *Lock value.
4477 OrderAccess::fence();
4478 for (;;) {
4479 w = *Lock;
4480 if ((w & LOCKBIT) == 0) {
4481 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4482 ev->OnList = 0;
4483 // We call ::Release while holding the outer lock, thus
4484 // artificially lengthening the critical section.
4485 // Consider deferring the ::Release() until the subsequent unlock(),
4486 // after we've dropped the outer lock.
4487 if (ReleaseAfter != NULL) {
4488 ParkEvent::Release(ReleaseAfter);
4489 }
4490 return;
4491 }
4492 continue; // Interference -- *Lock changed -- Just retry
4493 }
4494 assert(w & LOCKBIT, "invariant");
4495 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4496 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4497 }
4498
4499 while (ev->OnList != 0) {
4500 ev->park();
4501 }
4502 }
4503 }
4504
4505 // Release() must extract a successor from the list and then wake that thread.
4506 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4507 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4508 // Release() would :
4509 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4510 // (B) Extract a successor from the private list "in-hand"
4511 // (C) attempt to CAS() the residual back into *Lock over null.
4512 // If there were any newly arrived threads and the CAS() would fail.
4513 // In that case Release() would detach the RATs, re-merge the list in-hand
4514 // with the RATs and repeat as needed. Alternately, Release() might
4515 // detach and extract a successor, but then pass the residual list to the wakee.
4516 // The wakee would be responsible for reattaching and remerging before it
4517 // competed for the lock.
4518 //
4519 // Both "pop" and DMR are immune from ABA corruption -- there can be
4520 // multiple concurrent pushers, but only one popper or detacher.
4521 // This implementation pops from the head of the list. This is unfair,
4522 // but tends to provide excellent throughput as hot threads remain hot.
4523 // (We wake recently run threads first).
4524 //
4525 // All paths through muxRelease() will execute a CAS.
4526 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4527 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4528 // executed within the critical section are complete and globally visible before the
4529 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4530 void Thread::muxRelease(volatile intptr_t * Lock) {
4531 for (;;) {
4532 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4533 assert(w & LOCKBIT, "invariant");
4534 if (w == LOCKBIT) return;
4535 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4536 assert(List != NULL, "invariant");
4537 assert(List->OnList == intptr_t(Lock), "invariant");
4538 ParkEvent * const nxt = List->ListNext;
4539 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4540
4541 // The following CAS() releases the lock and pops the head element.
4542 // The CAS() also ratifies the previously fetched lock-word value.
4543 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4544 continue;
4545 }
4546 List->OnList = 0;
4547 OrderAccess::fence();
4548 List->unpark();
4549 return;
4550 }
4551 }
4552
4553
4554 void Threads::verify() {
4555 ALL_JAVA_THREADS(p) {
4556 p->verify();
4557 }
4558 VMThread* thread = VMThread::vm_thread();
4559 if (thread != NULL) thread->verify();
4560 }