1 /*
2 * Copyright (c) 1997, 2018, 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 "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/workgroup.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "interpreter/linkResolver.hpp"
41 #include "interpreter/oopMapCache.hpp"
42 #include "jvmtifiles/jvmtiEnv.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logConfiguration.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/typeArrayOop.inline.hpp"
55 #include "oops/verifyOopClosure.hpp"
56 #include "prims/jvm_misc.hpp"
57 #include "prims/jvmtiExport.hpp"
58 #include "prims/jvmtiThreadState.hpp"
59 #include "prims/privilegedStack.hpp"
60 #include "runtime/arguments.hpp"
61 #include "runtime/atomic.hpp"
62 #include "runtime/biasedLocking.hpp"
63 #include "runtime/commandLineFlagConstraintList.hpp"
64 #include "runtime/commandLineFlagWriteableList.hpp"
65 #include "runtime/commandLineFlagRangeList.hpp"
66 #include "runtime/deoptimization.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.hpp"
69 #include "runtime/handshake.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/interfaceSupport.hpp"
72 #include "runtime/java.hpp"
73 #include "runtime/javaCalls.hpp"
74 #include "runtime/jniPeriodicChecker.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/prefetch.inline.hpp"
81 #include "runtime/safepoint.hpp"
82 #include "runtime/safepointMechanism.inline.hpp"
83 #include "runtime/sharedRuntime.hpp"
84 #include "runtime/statSampler.hpp"
85 #include "runtime/stubRoutines.hpp"
86 #include "runtime/sweeper.hpp"
87 #include "runtime/task.hpp"
88 #include "runtime/thread.inline.hpp"
89 #include "runtime/threadCritical.hpp"
90 #include "runtime/threadSMR.inline.hpp"
91 #include "runtime/timer.hpp"
92 #include "runtime/timerTrace.hpp"
93 #include "runtime/vframe.hpp"
94 #include "runtime/vframeArray.hpp"
95 #include "runtime/vframe_hp.hpp"
96 #include "runtime/vmThread.hpp"
97 #include "runtime/vm_operations.hpp"
98 #include "runtime/vm_version.hpp"
99 #include "services/attachListener.hpp"
100 #include "services/management.hpp"
101 #include "services/memTracker.hpp"
102 #include "services/threadService.hpp"
103 #include "trace/traceMacros.hpp"
104 #include "trace/tracing.hpp"
105 #include "utilities/align.hpp"
106 #include "utilities/defaultStream.hpp"
107 #include "utilities/dtrace.hpp"
108 #include "utilities/events.hpp"
109 #include "utilities/macros.hpp"
110 #include "utilities/preserveException.hpp"
111 #include "utilities/vmError.hpp"
112 #if INCLUDE_ALL_GCS
113 #include "gc/cms/concurrentMarkSweepThread.hpp"
114 #include "gc/g1/concurrentMarkThread.inline.hpp"
115 #include "gc/parallel/pcTasks.hpp"
116 #endif // INCLUDE_ALL_GCS
117 #if INCLUDE_JVMCI
118 #include "jvmci/jvmciCompiler.hpp"
119 #include "jvmci/jvmciRuntime.hpp"
120 #include "logging/logHandle.hpp"
121 #endif
122 #ifdef COMPILER1
123 #include "c1/c1_Compiler.hpp"
124 #endif
125 #ifdef COMPILER2
126 #include "opto/c2compiler.hpp"
127 #include "opto/idealGraphPrinter.hpp"
128 #endif
129 #if INCLUDE_RTM_OPT
130 #include "runtime/rtmLocking.hpp"
131 #endif
132
133 // Initialization after module runtime initialization
134 void universe_post_module_init(); // must happen after call_initPhase2
135
136 #ifdef DTRACE_ENABLED
137
138 // Only bother with this argument setup if dtrace is available
139
140 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
141 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
142
143 #define DTRACE_THREAD_PROBE(probe, javathread) \
144 { \
145 ResourceMark rm(this); \
146 int len = 0; \
147 const char* name = (javathread)->get_thread_name(); \
148 len = strlen(name); \
149 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
150 (char *) name, len, \
151 java_lang_Thread::thread_id((javathread)->threadObj()), \
152 (uintptr_t) (javathread)->osthread()->thread_id(), \
153 java_lang_Thread::is_daemon((javathread)->threadObj())); \
154 }
155
156 #else // ndef DTRACE_ENABLED
157
158 #define DTRACE_THREAD_PROBE(probe, javathread)
159
160 #endif // ndef DTRACE_ENABLED
161
162 #ifndef USE_LIBRARY_BASED_TLS_ONLY
163 // Current thread is maintained as a thread-local variable
164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
165 #endif
166 // Class hierarchy
167 // - Thread
168 // - VMThread
169 // - WatcherThread
170 // - ConcurrentMarkSweepThread
171 // - JavaThread
172 // - CompilerThread
173
174 // ======= Thread ========
175 // Support for forcing alignment of thread objects for biased locking
176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
177 if (UseBiasedLocking) {
178 const int alignment = markOopDesc::biased_lock_alignment;
179 size_t aligned_size = size + (alignment - sizeof(intptr_t));
180 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
181 : AllocateHeap(aligned_size, flags, CURRENT_PC,
182 AllocFailStrategy::RETURN_NULL);
183 void* aligned_addr = align_up(real_malloc_addr, alignment);
184 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
185 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
186 "JavaThread alignment code overflowed allocated storage");
187 if (aligned_addr != real_malloc_addr) {
188 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
189 p2i(real_malloc_addr),
190 p2i(aligned_addr));
191 }
192 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
193 return aligned_addr;
194 } else {
195 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
196 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
197 }
198 }
199
200 void Thread::operator delete(void* p) {
201 if (UseBiasedLocking) {
202 FreeHeap(((Thread*) p)->_real_malloc_address);
203 } else {
204 FreeHeap(p);
205 }
206 }
207
208 void JavaThread::smr_delete() {
209 if (_on_thread_list) {
210 ThreadsSMRSupport::smr_delete(this);
211 } else {
212 delete this;
213 }
214 }
215
216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
217 // JavaThread
218
219
220 Thread::Thread() {
221 // stack and get_thread
222 set_stack_base(NULL);
223 set_stack_size(0);
224 set_self_raw_id(0);
225 set_lgrp_id(-1);
226 DEBUG_ONLY(clear_suspendible_thread();)
227
228 // allocated data structures
229 set_osthread(NULL);
230 set_resource_area(new (mtThread)ResourceArea());
231 DEBUG_ONLY(_current_resource_mark = NULL;)
232 set_handle_area(new (mtThread) HandleArea(NULL));
233 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
234 set_active_handles(NULL);
235 set_free_handle_block(NULL);
236 set_last_handle_mark(NULL);
237
238 // This initial value ==> never claimed.
239 _oops_do_parity = 0;
240 _threads_hazard_ptr = NULL;
241 _nested_threads_hazard_ptr = NULL;
242 _nested_threads_hazard_ptr_cnt = 0;
243
244 // the handle mark links itself to last_handle_mark
245 new HandleMark(this);
246
247 // plain initialization
248 debug_only(_owned_locks = NULL;)
249 debug_only(_allow_allocation_count = 0;)
250 NOT_PRODUCT(_allow_safepoint_count = 0;)
251 NOT_PRODUCT(_skip_gcalot = false;)
252 _jvmti_env_iteration_count = 0;
253 set_allocated_bytes(0);
254 _vm_operation_started_count = 0;
255 _vm_operation_completed_count = 0;
256 _current_pending_monitor = NULL;
257 _current_pending_monitor_is_from_java = true;
258 _current_waiting_monitor = NULL;
259 _num_nested_signal = 0;
260 omFreeList = NULL;
261 omFreeCount = 0;
262 omFreeProvision = 32;
263 omInUseList = NULL;
264 omInUseCount = 0;
265
266 #ifdef ASSERT
267 _visited_for_critical_count = false;
268 #endif
269
270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
271 Monitor::_safepoint_check_sometimes);
272 _suspend_flags = 0;
273
274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
275 _hashStateX = os::random();
276 _hashStateY = 842502087;
277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
278 _hashStateW = 273326509;
279
280 _OnTrap = 0;
281 _schedctl = NULL;
282 _Stalled = 0;
283 _TypeTag = 0x2BAD;
284
285 // Many of the following fields are effectively final - immutable
286 // Note that nascent threads can't use the Native Monitor-Mutex
287 // construct until the _MutexEvent is initialized ...
288 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
289 // we might instead use a stack of ParkEvents that we could provision on-demand.
290 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
291 // and ::Release()
292 _ParkEvent = ParkEvent::Allocate(this);
293 _SleepEvent = ParkEvent::Allocate(this);
294 _MutexEvent = ParkEvent::Allocate(this);
295 _MuxEvent = ParkEvent::Allocate(this);
296
297 #ifdef CHECK_UNHANDLED_OOPS
298 if (CheckUnhandledOops) {
299 _unhandled_oops = new UnhandledOops(this);
300 }
301 #endif // CHECK_UNHANDLED_OOPS
302 #ifdef ASSERT
303 if (UseBiasedLocking) {
304 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
307 "bug in forced alignment of thread objects");
308 }
309 #endif // ASSERT
310 }
311
312 void Thread::initialize_thread_current() {
313 #ifndef USE_LIBRARY_BASED_TLS_ONLY
314 assert(_thr_current == NULL, "Thread::current already initialized");
315 _thr_current = this;
316 #endif
317 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
318 ThreadLocalStorage::set_thread(this);
319 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
320 }
321
322 void Thread::clear_thread_current() {
323 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
325 _thr_current = NULL;
326 #endif
327 ThreadLocalStorage::set_thread(NULL);
328 }
329
330 void Thread::record_stack_base_and_size() {
331 set_stack_base(os::current_stack_base());
332 set_stack_size(os::current_stack_size());
333 // CR 7190089: on Solaris, primordial thread's stack is adjusted
334 // in initialize_thread(). Without the adjustment, stack size is
335 // incorrect if stack is set to unlimited (ulimit -s unlimited).
336 // So far, only Solaris has real implementation of initialize_thread().
337 //
338 // set up any platform-specific state.
339 os::initialize_thread(this);
340
341 // Set stack limits after thread is initialized.
342 if (is_Java_thread()) {
343 ((JavaThread*) this)->set_stack_overflow_limit();
344 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
345 }
346 #if INCLUDE_NMT
347 // record thread's native stack, stack grows downward
348 MemTracker::record_thread_stack(stack_end(), stack_size());
349 #endif // INCLUDE_NMT
350 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
351 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
352 os::current_thread_id(), p2i(stack_base() - stack_size()),
353 p2i(stack_base()), stack_size()/1024);
354 }
355
356
357 Thread::~Thread() {
358 EVENT_THREAD_DESTRUCT(this);
359
360 // stack_base can be NULL if the thread is never started or exited before
361 // record_stack_base_and_size called. Although, we would like to ensure
362 // that all started threads do call record_stack_base_and_size(), there is
363 // not proper way to enforce that.
364 #if INCLUDE_NMT
365 if (_stack_base != NULL) {
366 MemTracker::release_thread_stack(stack_end(), stack_size());
367 #ifdef ASSERT
368 set_stack_base(NULL);
369 #endif
370 }
371 #endif // INCLUDE_NMT
372
373 // deallocate data structures
374 delete resource_area();
375 // since the handle marks are using the handle area, we have to deallocated the root
376 // handle mark before deallocating the thread's handle area,
377 assert(last_handle_mark() != NULL, "check we have an element");
378 delete last_handle_mark();
379 assert(last_handle_mark() == NULL, "check we have reached the end");
380
381 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
382 // We NULL out the fields for good hygiene.
383 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
384 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
385 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
386 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
387
388 delete handle_area();
389 delete metadata_handles();
390
391 // SR_handler uses this as a termination indicator -
392 // needs to happen before os::free_thread()
393 delete _SR_lock;
394 _SR_lock = NULL;
395
396 // osthread() can be NULL, if creation of thread failed.
397 if (osthread() != NULL) os::free_thread(osthread());
398
399 // clear Thread::current if thread is deleting itself.
400 // Needed to ensure JNI correctly detects non-attached threads.
401 if (this == Thread::current()) {
402 clear_thread_current();
403 }
404
405 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
406 }
407
408 // NOTE: dummy function for assertion purpose.
409 void Thread::run() {
410 ShouldNotReachHere();
411 }
412
413 #ifdef ASSERT
414 // A JavaThread is considered "dangling" if it is not the current
415 // thread, has been added the Threads list, the system is not at a
416 // safepoint and the Thread is not "protected".
417 //
418 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
419 assert(!thread->is_Java_thread() || Thread::current() == thread ||
420 !((JavaThread *) thread)->on_thread_list() ||
421 SafepointSynchronize::is_at_safepoint() ||
422 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
423 "possibility of dangling Thread pointer");
424 }
425 #endif
426
427 ThreadPriority Thread::get_priority(const Thread* const thread) {
428 ThreadPriority priority;
429 // Can return an error!
430 (void)os::get_priority(thread, priority);
431 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
432 return priority;
433 }
434
435 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
436 debug_only(check_for_dangling_thread_pointer(thread);)
437 // Can return an error!
438 (void)os::set_priority(thread, priority);
439 }
440
441
442 void Thread::start(Thread* thread) {
443 // Start is different from resume in that its safety is guaranteed by context or
444 // being called from a Java method synchronized on the Thread object.
445 if (!DisableStartThread) {
446 if (thread->is_Java_thread()) {
447 // Initialize the thread state to RUNNABLE before starting this thread.
448 // Can not set it after the thread started because we do not know the
449 // exact thread state at that time. It could be in MONITOR_WAIT or
450 // in SLEEPING or some other state.
451 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
452 java_lang_Thread::RUNNABLE);
453 }
454 os::start_thread(thread);
455 }
456 }
457
458 // Enqueue a VM_Operation to do the job for us - sometime later
459 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
460 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
461 VMThread::execute(vm_stop);
462 }
463
464
465 // Check if an external suspend request has completed (or has been
466 // cancelled). Returns true if the thread is externally suspended and
467 // false otherwise.
468 //
469 // The bits parameter returns information about the code path through
470 // the routine. Useful for debugging:
471 //
472 // set in is_ext_suspend_completed():
473 // 0x00000001 - routine was entered
474 // 0x00000010 - routine return false at end
475 // 0x00000100 - thread exited (return false)
476 // 0x00000200 - suspend request cancelled (return false)
477 // 0x00000400 - thread suspended (return true)
478 // 0x00001000 - thread is in a suspend equivalent state (return true)
479 // 0x00002000 - thread is native and walkable (return true)
480 // 0x00004000 - thread is native_trans and walkable (needed retry)
481 //
482 // set in wait_for_ext_suspend_completion():
483 // 0x00010000 - routine was entered
484 // 0x00020000 - suspend request cancelled before loop (return false)
485 // 0x00040000 - thread suspended before loop (return true)
486 // 0x00080000 - suspend request cancelled in loop (return false)
487 // 0x00100000 - thread suspended in loop (return true)
488 // 0x00200000 - suspend not completed during retry loop (return false)
489
490 // Helper class for tracing suspend wait debug bits.
491 //
492 // 0x00000100 indicates that the target thread exited before it could
493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
494 // 0x00080000 each indicate a cancelled suspend request so they don't
495 // count as wait failures either.
496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
497
498 class TraceSuspendDebugBits : public StackObj {
499 private:
500 JavaThread * jt;
501 bool is_wait;
502 bool called_by_wait; // meaningful when !is_wait
503 uint32_t * bits;
504
505 public:
506 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
507 uint32_t *_bits) {
508 jt = _jt;
509 is_wait = _is_wait;
510 called_by_wait = _called_by_wait;
511 bits = _bits;
512 }
513
514 ~TraceSuspendDebugBits() {
515 if (!is_wait) {
516 #if 1
517 // By default, don't trace bits for is_ext_suspend_completed() calls.
518 // That trace is very chatty.
519 return;
520 #else
521 if (!called_by_wait) {
522 // If tracing for is_ext_suspend_completed() is enabled, then only
523 // trace calls to it from wait_for_ext_suspend_completion()
524 return;
525 }
526 #endif
527 }
528
529 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
530 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
531 MutexLocker ml(Threads_lock); // needed for get_thread_name()
532 ResourceMark rm;
533
534 tty->print_cr(
535 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
536 jt->get_thread_name(), *bits);
537
538 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
539 }
540 }
541 }
542 };
543 #undef DEBUG_FALSE_BITS
544
545
546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
547 uint32_t *bits) {
548 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
549
550 bool did_trans_retry = false; // only do thread_in_native_trans retry once
551 bool do_trans_retry; // flag to force the retry
552
553 *bits |= 0x00000001;
554
555 do {
556 do_trans_retry = false;
557
558 if (is_exiting()) {
559 // Thread is in the process of exiting. This is always checked
560 // first to reduce the risk of dereferencing a freed JavaThread.
561 *bits |= 0x00000100;
562 return false;
563 }
564
565 if (!is_external_suspend()) {
566 // Suspend request is cancelled. This is always checked before
567 // is_ext_suspended() to reduce the risk of a rogue resume
568 // confusing the thread that made the suspend request.
569 *bits |= 0x00000200;
570 return false;
571 }
572
573 if (is_ext_suspended()) {
574 // thread is suspended
575 *bits |= 0x00000400;
576 return true;
577 }
578
579 // Now that we no longer do hard suspends of threads running
580 // native code, the target thread can be changing thread state
581 // while we are in this routine:
582 //
583 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
584 //
585 // We save a copy of the thread state as observed at this moment
586 // and make our decision about suspend completeness based on the
587 // copy. This closes the race where the thread state is seen as
588 // _thread_in_native_trans in the if-thread_blocked check, but is
589 // seen as _thread_blocked in if-thread_in_native_trans check.
590 JavaThreadState save_state = thread_state();
591
592 if (save_state == _thread_blocked && is_suspend_equivalent()) {
593 // If the thread's state is _thread_blocked and this blocking
594 // condition is known to be equivalent to a suspend, then we can
595 // consider the thread to be externally suspended. This means that
596 // the code that sets _thread_blocked has been modified to do
597 // self-suspension if the blocking condition releases. We also
598 // used to check for CONDVAR_WAIT here, but that is now covered by
599 // the _thread_blocked with self-suspension check.
600 //
601 // Return true since we wouldn't be here unless there was still an
602 // external suspend request.
603 *bits |= 0x00001000;
604 return true;
605 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
606 // Threads running native code will self-suspend on native==>VM/Java
607 // transitions. If its stack is walkable (should always be the case
608 // unless this function is called before the actual java_suspend()
609 // call), then the wait is done.
610 *bits |= 0x00002000;
611 return true;
612 } else if (!called_by_wait && !did_trans_retry &&
613 save_state == _thread_in_native_trans &&
614 frame_anchor()->walkable()) {
615 // The thread is transitioning from thread_in_native to another
616 // thread state. check_safepoint_and_suspend_for_native_trans()
617 // will force the thread to self-suspend. If it hasn't gotten
618 // there yet we may have caught the thread in-between the native
619 // code check above and the self-suspend. Lucky us. If we were
620 // called by wait_for_ext_suspend_completion(), then it
621 // will be doing the retries so we don't have to.
622 //
623 // Since we use the saved thread state in the if-statement above,
624 // there is a chance that the thread has already transitioned to
625 // _thread_blocked by the time we get here. In that case, we will
626 // make a single unnecessary pass through the logic below. This
627 // doesn't hurt anything since we still do the trans retry.
628
629 *bits |= 0x00004000;
630
631 // Once the thread leaves thread_in_native_trans for another
632 // thread state, we break out of this retry loop. We shouldn't
633 // need this flag to prevent us from getting back here, but
634 // sometimes paranoia is good.
635 did_trans_retry = true;
636
637 // We wait for the thread to transition to a more usable state.
638 for (int i = 1; i <= SuspendRetryCount; i++) {
639 // We used to do an "os::yield_all(i)" call here with the intention
640 // that yielding would increase on each retry. However, the parameter
641 // is ignored on Linux which means the yield didn't scale up. Waiting
642 // on the SR_lock below provides a much more predictable scale up for
643 // the delay. It also provides a simple/direct point to check for any
644 // safepoint requests from the VMThread
645
646 // temporarily drops SR_lock while doing wait with safepoint check
647 // (if we're a JavaThread - the WatcherThread can also call this)
648 // and increase delay with each retry
649 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
650
651 // check the actual thread state instead of what we saved above
652 if (thread_state() != _thread_in_native_trans) {
653 // the thread has transitioned to another thread state so
654 // try all the checks (except this one) one more time.
655 do_trans_retry = true;
656 break;
657 }
658 } // end retry loop
659
660
661 }
662 } while (do_trans_retry);
663
664 *bits |= 0x00000010;
665 return false;
666 }
667
668 // Wait for an external suspend request to complete (or be cancelled).
669 // Returns true if the thread is externally suspended and false otherwise.
670 //
671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
672 uint32_t *bits) {
673 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
674 false /* !called_by_wait */, bits);
675
676 // local flag copies to minimize SR_lock hold time
677 bool is_suspended;
678 bool pending;
679 uint32_t reset_bits;
680
681 // set a marker so is_ext_suspend_completed() knows we are the caller
682 *bits |= 0x00010000;
683
684 // We use reset_bits to reinitialize the bits value at the top of
685 // each retry loop. This allows the caller to make use of any
686 // unused bits for their own marking purposes.
687 reset_bits = *bits;
688
689 {
690 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
691 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
692 delay, bits);
693 pending = is_external_suspend();
694 }
695 // must release SR_lock to allow suspension to complete
696
697 if (!pending) {
698 // A cancelled suspend request is the only false return from
699 // is_ext_suspend_completed() that keeps us from entering the
700 // retry loop.
701 *bits |= 0x00020000;
702 return false;
703 }
704
705 if (is_suspended) {
706 *bits |= 0x00040000;
707 return true;
708 }
709
710 for (int i = 1; i <= retries; i++) {
711 *bits = reset_bits; // reinit to only track last retry
712
713 // We used to do an "os::yield_all(i)" call here with the intention
714 // that yielding would increase on each retry. However, the parameter
715 // is ignored on Linux which means the yield didn't scale up. Waiting
716 // on the SR_lock below provides a much more predictable scale up for
717 // the delay. It also provides a simple/direct point to check for any
718 // safepoint requests from the VMThread
719
720 {
721 MutexLocker ml(SR_lock());
722 // wait with safepoint check (if we're a JavaThread - the WatcherThread
723 // can also call this) and increase delay with each retry
724 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
725
726 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
727 delay, bits);
728
729 // It is possible for the external suspend request to be cancelled
730 // (by a resume) before the actual suspend operation is completed.
731 // Refresh our local copy to see if we still need to wait.
732 pending = is_external_suspend();
733 }
734
735 if (!pending) {
736 // A cancelled suspend request is the only false return from
737 // is_ext_suspend_completed() that keeps us from staying in the
738 // retry loop.
739 *bits |= 0x00080000;
740 return false;
741 }
742
743 if (is_suspended) {
744 *bits |= 0x00100000;
745 return true;
746 }
747 } // end retry loop
748
749 // thread did not suspend after all our retries
750 *bits |= 0x00200000;
751 return false;
752 }
753
754 // Called from API entry points which perform stack walking. If the
755 // associated JavaThread is the current thread, then wait_for_suspend
756 // is not used. Otherwise, it determines if we should wait for the
757 // "other" thread to complete external suspension. (NOTE: in future
758 // releases the suspension mechanism should be reimplemented so this
759 // is not necessary.)
760 //
761 bool
762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
763 if (this != JavaThread::current()) {
764 // "other" threads require special handling.
765 if (wait_for_suspend) {
766 // We are allowed to wait for the external suspend to complete
767 // so give the other thread a chance to get suspended.
768 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
769 SuspendRetryDelay, bits)) {
770 // Didn't make it so let the caller know.
771 return false;
772 }
773 }
774 // We aren't allowed to wait for the external suspend to complete
775 // so if the other thread isn't externally suspended we need to
776 // let the caller know.
777 else if (!is_ext_suspend_completed_with_lock(bits)) {
778 return false;
779 }
780 }
781
782 return true;
783 }
784
785 #ifndef PRODUCT
786 void JavaThread::record_jump(address target, address instr, const char* file,
787 int line) {
788
789 // This should not need to be atomic as the only way for simultaneous
790 // updates is via interrupts. Even then this should be rare or non-existent
791 // and we don't care that much anyway.
792
793 int index = _jmp_ring_index;
794 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
795 _jmp_ring[index]._target = (intptr_t) target;
796 _jmp_ring[index]._instruction = (intptr_t) instr;
797 _jmp_ring[index]._file = file;
798 _jmp_ring[index]._line = line;
799 }
800 #endif // PRODUCT
801
802 void Thread::interrupt(Thread* thread) {
803 debug_only(check_for_dangling_thread_pointer(thread);)
804 os::interrupt(thread);
805 }
806
807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
808 debug_only(check_for_dangling_thread_pointer(thread);)
809 // Note: If clear_interrupted==false, this simply fetches and
810 // returns the value of the field osthread()->interrupted().
811 return os::is_interrupted(thread, clear_interrupted);
812 }
813
814
815 // GC Support
816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
817 int thread_parity = _oops_do_parity;
818 if (thread_parity != strong_roots_parity) {
819 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
820 if (res == thread_parity) {
821 return true;
822 } else {
823 guarantee(res == strong_roots_parity, "Or else what?");
824 return false;
825 }
826 }
827 return false;
828 }
829
830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
831 active_handles()->oops_do(f);
832 // Do oop for ThreadShadow
833 f->do_oop((oop*)&_pending_exception);
834 handle_area()->oops_do(f);
835
836 if (MonitorInUseLists) {
837 // When using thread local monitor lists, we scan them here,
838 // and the remaining global monitors in ObjectSynchronizer::oops_do().
839 ObjectSynchronizer::thread_local_used_oops_do(this, f);
840 }
841 }
842
843 void Thread::metadata_handles_do(void f(Metadata*)) {
844 // Only walk the Handles in Thread.
845 if (metadata_handles() != NULL) {
846 for (int i = 0; i< metadata_handles()->length(); i++) {
847 f(metadata_handles()->at(i));
848 }
849 }
850 }
851
852 void Thread::print_on(outputStream* st) const {
853 // get_priority assumes osthread initialized
854 if (osthread() != NULL) {
855 int os_prio;
856 if (os::get_native_priority(this, &os_prio) == OS_OK) {
857 st->print("os_prio=%d ", os_prio);
858 }
859 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
860 ext().print_on(st);
861 osthread()->print_on(st);
862 }
863 if (_threads_hazard_ptr != NULL) {
864 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
865 }
866 if (_nested_threads_hazard_ptr != NULL) {
867 print_nested_threads_hazard_ptrs_on(st);
868 }
869 st->print(" ");
870 debug_only(if (WizardMode) print_owned_locks_on(st);)
871 }
872
873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
874 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
875
876 if (EnableThreadSMRStatistics) {
877 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
878 }
879 st->print(", _nested_threads_hazard_ptrs=");
880 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
881 node = node->next()) {
882 if (node != _nested_threads_hazard_ptr) {
883 // First node does not need a comma-space separator.
884 st->print(", ");
885 }
886 st->print(INTPTR_FORMAT, p2i(node->t_list()));
887 }
888 }
889
890 // Thread::print_on_error() is called by fatal error handler. Don't use
891 // any lock or allocate memory.
892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
893 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
894
895 if (is_VM_thread()) { st->print("VMThread"); }
896 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
897 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
898 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
899 else { st->print("Thread"); }
900
901 if (is_Named_thread()) {
902 st->print(" \"%s\"", name());
903 }
904
905 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
906 p2i(stack_end()), p2i(stack_base()));
907
908 if (osthread()) {
909 st->print(" [id=%d]", osthread()->thread_id());
910 }
911
912 if (_threads_hazard_ptr != NULL) {
913 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
914 }
915 if (_nested_threads_hazard_ptr != NULL) {
916 print_nested_threads_hazard_ptrs_on(st);
917 }
918 }
919
920 void Thread::print_value_on(outputStream* st) const {
921 if (is_Named_thread()) {
922 st->print(" \"%s\" ", name());
923 }
924 st->print(INTPTR_FORMAT, p2i(this)); // print address
925 }
926
927 #ifdef ASSERT
928 void Thread::print_owned_locks_on(outputStream* st) const {
929 Monitor *cur = _owned_locks;
930 if (cur == NULL) {
931 st->print(" (no locks) ");
932 } else {
933 st->print_cr(" Locks owned:");
934 while (cur) {
935 cur->print_on(st);
936 cur = cur->next();
937 }
938 }
939 }
940
941 static int ref_use_count = 0;
942
943 bool Thread::owns_locks_but_compiled_lock() const {
944 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
945 if (cur != Compile_lock) return true;
946 }
947 return false;
948 }
949
950
951 #endif
952
953 #ifndef PRODUCT
954
955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
957 // no threads which allow_vm_block's are held
958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
959 // Check if current thread is allowed to block at a safepoint
960 if (!(_allow_safepoint_count == 0)) {
961 fatal("Possible safepoint reached by thread that does not allow it");
962 }
963 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
964 fatal("LEAF method calling lock?");
965 }
966
967 #ifdef ASSERT
968 if (potential_vm_operation && is_Java_thread()
969 && !Universe::is_bootstrapping()) {
970 // Make sure we do not hold any locks that the VM thread also uses.
971 // This could potentially lead to deadlocks
972 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
973 // Threads_lock is special, since the safepoint synchronization will not start before this is
974 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
975 // since it is used to transfer control between JavaThreads and the VMThread
976 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
977 if ((cur->allow_vm_block() &&
978 cur != Threads_lock &&
979 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
980 cur != VMOperationRequest_lock &&
981 cur != VMOperationQueue_lock) ||
982 cur->rank() == Mutex::special) {
983 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
984 }
985 }
986 }
987
988 if (GCALotAtAllSafepoints) {
989 // We could enter a safepoint here and thus have a gc
990 InterfaceSupport::check_gc_alot();
991 }
992 #endif
993 }
994 #endif
995
996 bool Thread::is_in_stack(address adr) const {
997 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
998 address end = os::current_stack_pointer();
999 // Allow non Java threads to call this without stack_base
1000 if (_stack_base == NULL) return true;
1001 if (stack_base() >= adr && adr >= end) return true;
1002
1003 return false;
1004 }
1005
1006 bool Thread::is_in_usable_stack(address adr) const {
1007 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1008 size_t usable_stack_size = _stack_size - stack_guard_size;
1009
1010 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1011 }
1012
1013
1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1016 // used for compilation in the future. If that change is made, the need for these methods
1017 // should be revisited, and they should be removed if possible.
1018
1019 bool Thread::is_lock_owned(address adr) const {
1020 return on_local_stack(adr);
1021 }
1022
1023 bool Thread::set_as_starting_thread() {
1024 // NOTE: this must be called inside the main thread.
1025 return os::create_main_thread((JavaThread*)this);
1026 }
1027
1028 static void initialize_class(Symbol* class_name, TRAPS) {
1029 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1030 InstanceKlass::cast(klass)->initialize(CHECK);
1031 }
1032
1033
1034 // Creates the initial ThreadGroup
1035 static Handle create_initial_thread_group(TRAPS) {
1036 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1037 InstanceKlass* ik = InstanceKlass::cast(k);
1038
1039 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1040 {
1041 JavaValue result(T_VOID);
1042 JavaCalls::call_special(&result,
1043 system_instance,
1044 ik,
1045 vmSymbols::object_initializer_name(),
1046 vmSymbols::void_method_signature(),
1047 CHECK_NH);
1048 }
1049 Universe::set_system_thread_group(system_instance());
1050
1051 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1052 {
1053 JavaValue result(T_VOID);
1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055 JavaCalls::call_special(&result,
1056 main_instance,
1057 ik,
1058 vmSymbols::object_initializer_name(),
1059 vmSymbols::threadgroup_string_void_signature(),
1060 system_instance,
1061 string,
1062 CHECK_NH);
1063 }
1064 return main_instance;
1065 }
1066
1067 // Creates the initial Thread
1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1069 TRAPS) {
1070 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1071 InstanceKlass* ik = InstanceKlass::cast(k);
1072 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1073
1074 java_lang_Thread::set_thread(thread_oop(), thread);
1075 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076 thread->set_threadObj(thread_oop());
1077
1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079
1080 JavaValue result(T_VOID);
1081 JavaCalls::call_special(&result, thread_oop,
1082 ik,
1083 vmSymbols::object_initializer_name(),
1084 vmSymbols::threadgroup_string_void_signature(),
1085 thread_group,
1086 string,
1087 CHECK_NULL);
1088 return thread_oop();
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098 fieldDescriptor fd;
1099 bool found = k != NULL &&
1100 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101 vmSymbols::string_signature(), &fd);
1102 if (found) {
1103 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104 if (name_oop == NULL) {
1105 return NULL;
1106 }
1107 const char* name = java_lang_String::as_utf8_string(name_oop,
1108 java_runtime_name,
1109 sizeof(java_runtime_name));
1110 return name;
1111 } else {
1112 return NULL;
1113 }
1114 }
1115
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120 fieldDescriptor fd;
1121 bool found = k != NULL &&
1122 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123 vmSymbols::string_signature(), &fd);
1124 if (found) {
1125 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126 if (name_oop == NULL) {
1127 return NULL;
1128 }
1129 const char* name = java_lang_String::as_utf8_string(name_oop,
1130 java_runtime_version,
1131 sizeof(java_runtime_version));
1132 return name;
1133 } else {
1134 return NULL;
1135 }
1136 }
1137
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142 if (klass != NULL) {
1143 JavaValue result(T_VOID);
1144 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145 vmSymbols::void_method_signature(),
1146 CHECK);
1147 }
1148 }
1149
1150 static void reset_vm_info_property(TRAPS) {
1151 // the vm info string
1152 ResourceMark rm(THREAD);
1153 const char *vm_info = VM_Version::vm_info_string();
1154
1155 // java.lang.System class
1156 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1157
1158 // setProperty arguments
1159 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1160 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1161
1162 // return value
1163 JavaValue r(T_OBJECT);
1164
1165 // public static String setProperty(String key, String value);
1166 JavaCalls::call_static(&r,
1167 klass,
1168 vmSymbols::setProperty_name(),
1169 vmSymbols::string_string_string_signature(),
1170 key_str,
1171 value_str,
1172 CHECK);
1173 }
1174
1175
1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1177 bool daemon, TRAPS) {
1178 assert(thread_group.not_null(), "thread group should be specified");
1179 assert(threadObj() == NULL, "should only create Java thread object once");
1180
1181 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1182 InstanceKlass* ik = InstanceKlass::cast(k);
1183 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1184
1185 java_lang_Thread::set_thread(thread_oop(), this);
1186 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1187 set_threadObj(thread_oop());
1188
1189 JavaValue result(T_VOID);
1190 if (thread_name != NULL) {
1191 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1192 // Thread gets assigned specified name and null target
1193 JavaCalls::call_special(&result,
1194 thread_oop,
1195 ik,
1196 vmSymbols::object_initializer_name(),
1197 vmSymbols::threadgroup_string_void_signature(),
1198 thread_group, // Argument 1
1199 name, // Argument 2
1200 THREAD);
1201 } else {
1202 // Thread gets assigned name "Thread-nnn" and null target
1203 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1204 JavaCalls::call_special(&result,
1205 thread_oop,
1206 ik,
1207 vmSymbols::object_initializer_name(),
1208 vmSymbols::threadgroup_runnable_void_signature(),
1209 thread_group, // Argument 1
1210 Handle(), // Argument 2
1211 THREAD);
1212 }
1213
1214
1215 if (daemon) {
1216 java_lang_Thread::set_daemon(thread_oop());
1217 }
1218
1219 if (HAS_PENDING_EXCEPTION) {
1220 return;
1221 }
1222
1223 Klass* group = SystemDictionary::ThreadGroup_klass();
1224 Handle threadObj(THREAD, this->threadObj());
1225
1226 JavaCalls::call_special(&result,
1227 thread_group,
1228 group,
1229 vmSymbols::add_method_name(),
1230 vmSymbols::thread_void_signature(),
1231 threadObj, // Arg 1
1232 THREAD);
1233 }
1234
1235 // NamedThread -- non-JavaThread subclasses with multiple
1236 // uniquely named instances should derive from this.
1237 NamedThread::NamedThread() : Thread() {
1238 _name = NULL;
1239 _processed_thread = NULL;
1240 _gc_id = GCId::undefined();
1241 }
1242
1243 NamedThread::~NamedThread() {
1244 if (_name != NULL) {
1245 FREE_C_HEAP_ARRAY(char, _name);
1246 _name = NULL;
1247 }
1248 }
1249
1250 void NamedThread::set_name(const char* format, ...) {
1251 guarantee(_name == NULL, "Only get to set name once.");
1252 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1253 guarantee(_name != NULL, "alloc failure");
1254 va_list ap;
1255 va_start(ap, format);
1256 jio_vsnprintf(_name, max_name_len, format, ap);
1257 va_end(ap);
1258 }
1259
1260 void NamedThread::initialize_named_thread() {
1261 set_native_thread_name(name());
1262 }
1263
1264 void NamedThread::print_on(outputStream* st) const {
1265 st->print("\"%s\" ", name());
1266 Thread::print_on(st);
1267 st->cr();
1268 }
1269
1270
1271 // ======= WatcherThread ========
1272
1273 // The watcher thread exists to simulate timer interrupts. It should
1274 // be replaced by an abstraction over whatever native support for
1275 // timer interrupts exists on the platform.
1276
1277 WatcherThread* WatcherThread::_watcher_thread = NULL;
1278 bool WatcherThread::_startable = false;
1279 volatile bool WatcherThread::_should_terminate = false;
1280
1281 WatcherThread::WatcherThread() : Thread() {
1282 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1283 if (os::create_thread(this, os::watcher_thread)) {
1284 _watcher_thread = this;
1285
1286 // Set the watcher thread to the highest OS priority which should not be
1287 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1288 // is created. The only normal thread using this priority is the reference
1289 // handler thread, which runs for very short intervals only.
1290 // If the VMThread's priority is not lower than the WatcherThread profiling
1291 // will be inaccurate.
1292 os::set_priority(this, MaxPriority);
1293 if (!DisableStartThread) {
1294 os::start_thread(this);
1295 }
1296 }
1297 }
1298
1299 int WatcherThread::sleep() const {
1300 // The WatcherThread does not participate in the safepoint protocol
1301 // for the PeriodicTask_lock because it is not a JavaThread.
1302 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1303
1304 if (_should_terminate) {
1305 // check for termination before we do any housekeeping or wait
1306 return 0; // we did not sleep.
1307 }
1308
1309 // remaining will be zero if there are no tasks,
1310 // causing the WatcherThread to sleep until a task is
1311 // enrolled
1312 int remaining = PeriodicTask::time_to_wait();
1313 int time_slept = 0;
1314
1315 // we expect this to timeout - we only ever get unparked when
1316 // we should terminate or when a new task has been enrolled
1317 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1318
1319 jlong time_before_loop = os::javaTimeNanos();
1320
1321 while (true) {
1322 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1323 remaining);
1324 jlong now = os::javaTimeNanos();
1325
1326 if (remaining == 0) {
1327 // if we didn't have any tasks we could have waited for a long time
1328 // consider the time_slept zero and reset time_before_loop
1329 time_slept = 0;
1330 time_before_loop = now;
1331 } else {
1332 // need to recalculate since we might have new tasks in _tasks
1333 time_slept = (int) ((now - time_before_loop) / 1000000);
1334 }
1335
1336 // Change to task list or spurious wakeup of some kind
1337 if (timedout || _should_terminate) {
1338 break;
1339 }
1340
1341 remaining = PeriodicTask::time_to_wait();
1342 if (remaining == 0) {
1343 // Last task was just disenrolled so loop around and wait until
1344 // another task gets enrolled
1345 continue;
1346 }
1347
1348 remaining -= time_slept;
1349 if (remaining <= 0) {
1350 break;
1351 }
1352 }
1353
1354 return time_slept;
1355 }
1356
1357 void WatcherThread::run() {
1358 assert(this == watcher_thread(), "just checking");
1359
1360 this->record_stack_base_and_size();
1361 this->set_native_thread_name(this->name());
1362 this->set_active_handles(JNIHandleBlock::allocate_block());
1363 while (true) {
1364 assert(watcher_thread() == Thread::current(), "thread consistency check");
1365 assert(watcher_thread() == this, "thread consistency check");
1366
1367 // Calculate how long it'll be until the next PeriodicTask work
1368 // should be done, and sleep that amount of time.
1369 int time_waited = sleep();
1370
1371 if (VMError::is_error_reported()) {
1372 // A fatal error has happened, the error handler(VMError::report_and_die)
1373 // should abort JVM after creating an error log file. However in some
1374 // rare cases, the error handler itself might deadlock. Here periodically
1375 // check for error reporting timeouts, and if it happens, just proceed to
1376 // abort the VM.
1377
1378 // This code is in WatcherThread because WatcherThread wakes up
1379 // periodically so the fatal error handler doesn't need to do anything;
1380 // also because the WatcherThread is less likely to crash than other
1381 // threads.
1382
1383 for (;;) {
1384 // Note: we use naked sleep in this loop because we want to avoid using
1385 // any kind of VM infrastructure which may be broken at this point.
1386 if (VMError::check_timeout()) {
1387 // We hit error reporting timeout. Error reporting was interrupted and
1388 // will be wrapping things up now (closing files etc). Give it some more
1389 // time, then quit the VM.
1390 os::naked_short_sleep(200);
1391 // Print a message to stderr.
1392 fdStream err(defaultStream::output_fd());
1393 err.print_raw_cr("# [ timer expired, abort... ]");
1394 // skip atexit/vm_exit/vm_abort hooks
1395 os::die();
1396 }
1397
1398 // Wait a second, then recheck for timeout.
1399 os::naked_short_sleep(999);
1400 }
1401 }
1402
1403 if (_should_terminate) {
1404 // check for termination before posting the next tick
1405 break;
1406 }
1407
1408 PeriodicTask::real_time_tick(time_waited);
1409 }
1410
1411 // Signal that it is terminated
1412 {
1413 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1414 _watcher_thread = NULL;
1415 Terminator_lock->notify();
1416 }
1417 }
1418
1419 void WatcherThread::start() {
1420 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1421
1422 if (watcher_thread() == NULL && _startable) {
1423 _should_terminate = false;
1424 // Create the single instance of WatcherThread
1425 new WatcherThread();
1426 }
1427 }
1428
1429 void WatcherThread::make_startable() {
1430 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1431 _startable = true;
1432 }
1433
1434 void WatcherThread::stop() {
1435 {
1436 // Follow normal safepoint aware lock enter protocol since the
1437 // WatcherThread is stopped by another JavaThread.
1438 MutexLocker ml(PeriodicTask_lock);
1439 _should_terminate = true;
1440
1441 WatcherThread* watcher = watcher_thread();
1442 if (watcher != NULL) {
1443 // unpark the WatcherThread so it can see that it should terminate
1444 watcher->unpark();
1445 }
1446 }
1447
1448 MutexLocker mu(Terminator_lock);
1449
1450 while (watcher_thread() != NULL) {
1451 // This wait should make safepoint checks, wait without a timeout,
1452 // and wait as a suspend-equivalent condition.
1453 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1454 Mutex::_as_suspend_equivalent_flag);
1455 }
1456 }
1457
1458 void WatcherThread::unpark() {
1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460 PeriodicTask_lock->notify();
1461 }
1462
1463 void WatcherThread::print_on(outputStream* st) const {
1464 st->print("\"%s\" ", name());
1465 Thread::print_on(st);
1466 st->cr();
1467 }
1468
1469 // ======= JavaThread ========
1470
1471 #if INCLUDE_JVMCI
1472
1473 jlong* JavaThread::_jvmci_old_thread_counters;
1474
1475 bool jvmci_counters_include(JavaThread* thread) {
1476 oop threadObj = thread->threadObj();
1477 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481 if (JVMCICounterSize > 0) {
1482 MutexLocker tl(Threads_lock);
1483 JavaThreadIteratorWithHandle jtiwh;
1484 for (int i = 0; i < array->length(); i++) {
1485 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1486 }
1487 for (; JavaThread *tp = jtiwh.next(); ) {
1488 if (jvmci_counters_include(tp)) {
1489 for (int i = 0; i < array->length(); i++) {
1490 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1491 }
1492 }
1493 }
1494 }
1495 }
1496
1497 #endif // INCLUDE_JVMCI
1498
1499 // A JavaThread is a normal Java thread
1500
1501 void JavaThread::initialize() {
1502 // Initialize fields
1503
1504 set_saved_exception_pc(NULL);
1505 set_threadObj(NULL);
1506 _anchor.clear();
1507 set_entry_point(NULL);
1508 set_jni_functions(jni_functions());
1509 set_callee_target(NULL);
1510 set_vm_result(NULL);
1511 set_vm_result_2(NULL);
1512 set_vframe_array_head(NULL);
1513 set_vframe_array_last(NULL);
1514 set_deferred_locals(NULL);
1515 set_deopt_mark(NULL);
1516 set_deopt_compiled_method(NULL);
1517 clear_must_deopt_id();
1518 set_monitor_chunks(NULL);
1519 set_next(NULL);
1520 _on_thread_list = false;
1521 set_thread_state(_thread_new);
1522 _terminated = _not_terminated;
1523 _privileged_stack_top = NULL;
1524 _array_for_gc = NULL;
1525 _suspend_equivalent = false;
1526 _in_deopt_handler = 0;
1527 _doing_unsafe_access = false;
1528 _stack_guard_state = stack_guard_unused;
1529 #if INCLUDE_JVMCI
1530 _pending_monitorenter = false;
1531 _pending_deoptimization = -1;
1532 _pending_failed_speculation = NULL;
1533 _pending_transfer_to_interpreter = false;
1534 _adjusting_comp_level = false;
1535 _jvmci._alternate_call_target = NULL;
1536 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1537 if (JVMCICounterSize > 0) {
1538 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1539 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1540 } else {
1541 _jvmci_counters = NULL;
1542 }
1543 #endif // INCLUDE_JVMCI
1544 _reserved_stack_activation = NULL; // stack base not known yet
1545 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1546 _exception_pc = 0;
1547 _exception_handler_pc = 0;
1548 _is_method_handle_return = 0;
1549 _jvmti_thread_state= NULL;
1550 _should_post_on_exceptions_flag = JNI_FALSE;
1551 _jvmti_get_loaded_classes_closure = NULL;
1552 _interp_only_mode = 0;
1553 _special_runtime_exit_condition = _no_async_condition;
1554 _pending_async_exception = NULL;
1555 _thread_stat = NULL;
1556 _thread_stat = new ThreadStatistics();
1557 _blocked_on_compilation = false;
1558 _jni_active_critical = 0;
1559 _pending_jni_exception_check_fn = NULL;
1560 _do_not_unlock_if_synchronized = false;
1561 _cached_monitor_info = NULL;
1562 _parker = Parker::Allocate(this);
1563
1564 #ifndef PRODUCT
1565 _jmp_ring_index = 0;
1566 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1567 record_jump(NULL, NULL, NULL, 0);
1568 }
1569 #endif // PRODUCT
1570
1571 // Setup safepoint state info for this thread
1572 ThreadSafepointState::create(this);
1573
1574 debug_only(_java_call_counter = 0);
1575
1576 // JVMTI PopFrame support
1577 _popframe_condition = popframe_inactive;
1578 _popframe_preserved_args = NULL;
1579 _popframe_preserved_args_size = 0;
1580 _frames_to_pop_failed_realloc = 0;
1581
1582 if (SafepointMechanism::uses_thread_local_poll()) {
1583 SafepointMechanism::initialize_header(this);
1584 }
1585
1586 pd_initialize();
1587 }
1588
1589 #if INCLUDE_ALL_GCS
1590 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1591 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1592 #endif // INCLUDE_ALL_GCS
1593
1594 JavaThread::JavaThread(bool is_attaching_via_jni) :
1595 Thread()
1596 #if INCLUDE_ALL_GCS
1597 , _satb_mark_queue(&_satb_mark_queue_set),
1598 _dirty_card_queue(&_dirty_card_queue_set)
1599 #endif // INCLUDE_ALL_GCS
1600 {
1601 initialize();
1602 if (is_attaching_via_jni) {
1603 _jni_attach_state = _attaching_via_jni;
1604 } else {
1605 _jni_attach_state = _not_attaching_via_jni;
1606 }
1607 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1608 }
1609
1610 bool JavaThread::reguard_stack(address cur_sp) {
1611 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1612 && _stack_guard_state != stack_guard_reserved_disabled) {
1613 return true; // Stack already guarded or guard pages not needed.
1614 }
1615
1616 if (register_stack_overflow()) {
1617 // For those architectures which have separate register and
1618 // memory stacks, we must check the register stack to see if
1619 // it has overflowed.
1620 return false;
1621 }
1622
1623 // Java code never executes within the yellow zone: the latter is only
1624 // there to provoke an exception during stack banging. If java code
1625 // is executing there, either StackShadowPages should be larger, or
1626 // some exception code in c1, c2 or the interpreter isn't unwinding
1627 // when it should.
1628 guarantee(cur_sp > stack_reserved_zone_base(),
1629 "not enough space to reguard - increase StackShadowPages");
1630 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1631 enable_stack_yellow_reserved_zone();
1632 if (reserved_stack_activation() != stack_base()) {
1633 set_reserved_stack_activation(stack_base());
1634 }
1635 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1636 set_reserved_stack_activation(stack_base());
1637 enable_stack_reserved_zone();
1638 }
1639 return true;
1640 }
1641
1642 bool JavaThread::reguard_stack(void) {
1643 return reguard_stack(os::current_stack_pointer());
1644 }
1645
1646
1647 void JavaThread::block_if_vm_exited() {
1648 if (_terminated == _vm_exited) {
1649 // _vm_exited is set at safepoint, and Threads_lock is never released
1650 // we will block here forever
1651 Threads_lock->lock_without_safepoint_check();
1652 ShouldNotReachHere();
1653 }
1654 }
1655
1656
1657 // Remove this ifdef when C1 is ported to the compiler interface.
1658 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1659 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1660
1661 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1662 Thread()
1663 #if INCLUDE_ALL_GCS
1664 , _satb_mark_queue(&_satb_mark_queue_set),
1665 _dirty_card_queue(&_dirty_card_queue_set)
1666 #endif // INCLUDE_ALL_GCS
1667 {
1668 initialize();
1669 _jni_attach_state = _not_attaching_via_jni;
1670 set_entry_point(entry_point);
1671 // Create the native thread itself.
1672 // %note runtime_23
1673 os::ThreadType thr_type = os::java_thread;
1674 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1675 os::java_thread;
1676 os::create_thread(this, thr_type, stack_sz);
1677 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1678 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1679 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1680 // the exception consists of creating the exception object & initializing it, initialization
1681 // will leave the VM via a JavaCall and then all locks must be unlocked).
1682 //
1683 // The thread is still suspended when we reach here. Thread must be explicit started
1684 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1685 // by calling Threads:add. The reason why this is not done here, is because the thread
1686 // object must be fully initialized (take a look at JVM_Start)
1687 }
1688
1689 JavaThread::~JavaThread() {
1690
1691 // JSR166 -- return the parker to the free list
1692 Parker::Release(_parker);
1693 _parker = NULL;
1694
1695 // Free any remaining previous UnrollBlock
1696 vframeArray* old_array = vframe_array_last();
1697
1698 if (old_array != NULL) {
1699 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1700 old_array->set_unroll_block(NULL);
1701 delete old_info;
1702 delete old_array;
1703 }
1704
1705 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1706 if (deferred != NULL) {
1707 // This can only happen if thread is destroyed before deoptimization occurs.
1708 assert(deferred->length() != 0, "empty array!");
1709 do {
1710 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1711 deferred->remove_at(0);
1712 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1713 delete dlv;
1714 } while (deferred->length() != 0);
1715 delete deferred;
1716 }
1717
1718 // All Java related clean up happens in exit
1719 ThreadSafepointState::destroy(this);
1720 if (_thread_stat != NULL) delete _thread_stat;
1721
1722 #if INCLUDE_JVMCI
1723 if (JVMCICounterSize > 0) {
1724 if (jvmci_counters_include(this)) {
1725 for (int i = 0; i < JVMCICounterSize; i++) {
1726 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1727 }
1728 }
1729 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1730 }
1731 #endif // INCLUDE_JVMCI
1732 }
1733
1734
1735 // The first routine called by a new Java thread
1736 void JavaThread::run() {
1737 // initialize thread-local alloc buffer related fields
1738 this->initialize_tlab();
1739
1740 // used to test validity of stack trace backs
1741 this->record_base_of_stack_pointer();
1742
1743 // Record real stack base and size.
1744 this->record_stack_base_and_size();
1745
1746 this->create_stack_guard_pages();
1747
1748 this->cache_global_variables();
1749
1750 // Thread is now sufficient initialized to be handled by the safepoint code as being
1751 // in the VM. Change thread state from _thread_new to _thread_in_vm
1752 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1753
1754 assert(JavaThread::current() == this, "sanity check");
1755 assert(!Thread::current()->owns_locks(), "sanity check");
1756
1757 DTRACE_THREAD_PROBE(start, this);
1758
1759 // This operation might block. We call that after all safepoint checks for a new thread has
1760 // been completed.
1761 this->set_active_handles(JNIHandleBlock::allocate_block());
1762
1763 if (JvmtiExport::should_post_thread_life()) {
1764 JvmtiExport::post_thread_start(this);
1765 }
1766
1767 EventThreadStart event;
1768 if (event.should_commit()) {
1769 event.set_thread(THREAD_TRACE_ID(this));
1770 event.commit();
1771 }
1772
1773 // We call another function to do the rest so we are sure that the stack addresses used
1774 // from there will be lower than the stack base just computed
1775 thread_main_inner();
1776
1777 // Note, thread is no longer valid at this point!
1778 }
1779
1780
1781 void JavaThread::thread_main_inner() {
1782 assert(JavaThread::current() == this, "sanity check");
1783 assert(this->threadObj() != NULL, "just checking");
1784
1785 // Execute thread entry point unless this thread has a pending exception
1786 // or has been stopped before starting.
1787 // Note: Due to JVM_StopThread we can have pending exceptions already!
1788 if (!this->has_pending_exception() &&
1789 !java_lang_Thread::is_stillborn(this->threadObj())) {
1790 {
1791 ResourceMark rm(this);
1792 this->set_native_thread_name(this->get_thread_name());
1793 }
1794 HandleMark hm(this);
1795 this->entry_point()(this, this);
1796 }
1797
1798 DTRACE_THREAD_PROBE(stop, this);
1799
1800 this->exit(false);
1801 this->smr_delete();
1802 }
1803
1804
1805 static void ensure_join(JavaThread* thread) {
1806 // We do not need to grab the Threads_lock, since we are operating on ourself.
1807 Handle threadObj(thread, thread->threadObj());
1808 assert(threadObj.not_null(), "java thread object must exist");
1809 ObjectLocker lock(threadObj, thread);
1810 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1811 thread->clear_pending_exception();
1812 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1813 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1814 // Clear the native thread instance - this makes isAlive return false and allows the join()
1815 // to complete once we've done the notify_all below
1816 java_lang_Thread::set_thread(threadObj(), NULL);
1817 lock.notify_all(thread);
1818 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1819 thread->clear_pending_exception();
1820 }
1821
1822
1823 // For any new cleanup additions, please check to see if they need to be applied to
1824 // cleanup_failed_attach_current_thread as well.
1825 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1826 assert(this == JavaThread::current(), "thread consistency check");
1827
1828 elapsedTimer _timer_exit_phase1;
1829 elapsedTimer _timer_exit_phase2;
1830 elapsedTimer _timer_exit_phase3;
1831 elapsedTimer _timer_exit_phase4;
1832
1833 if (log_is_enabled(Debug, os, thread, timer)) {
1834 _timer_exit_phase1.start();
1835 }
1836
1837 HandleMark hm(this);
1838 Handle uncaught_exception(this, this->pending_exception());
1839 this->clear_pending_exception();
1840 Handle threadObj(this, this->threadObj());
1841 assert(threadObj.not_null(), "Java thread object should be created");
1842
1843 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1844 {
1845 EXCEPTION_MARK;
1846
1847 CLEAR_PENDING_EXCEPTION;
1848 }
1849 if (!destroy_vm) {
1850 if (uncaught_exception.not_null()) {
1851 EXCEPTION_MARK;
1852 // Call method Thread.dispatchUncaughtException().
1853 Klass* thread_klass = SystemDictionary::Thread_klass();
1854 JavaValue result(T_VOID);
1855 JavaCalls::call_virtual(&result,
1856 threadObj, thread_klass,
1857 vmSymbols::dispatchUncaughtException_name(),
1858 vmSymbols::throwable_void_signature(),
1859 uncaught_exception,
1860 THREAD);
1861 if (HAS_PENDING_EXCEPTION) {
1862 ResourceMark rm(this);
1863 jio_fprintf(defaultStream::error_stream(),
1864 "\nException: %s thrown from the UncaughtExceptionHandler"
1865 " in thread \"%s\"\n",
1866 pending_exception()->klass()->external_name(),
1867 get_thread_name());
1868 CLEAR_PENDING_EXCEPTION;
1869 }
1870 }
1871
1872 // Called before the java thread exit since we want to read info
1873 // from java_lang_Thread object
1874 EventThreadEnd event;
1875 if (event.should_commit()) {
1876 event.set_thread(THREAD_TRACE_ID(this));
1877 event.commit();
1878 }
1879
1880 // Call after last event on thread
1881 EVENT_THREAD_EXIT(this);
1882
1883 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1884 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1885 // is deprecated anyhow.
1886 if (!is_Compiler_thread()) {
1887 int count = 3;
1888 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1889 EXCEPTION_MARK;
1890 JavaValue result(T_VOID);
1891 Klass* thread_klass = SystemDictionary::Thread_klass();
1892 JavaCalls::call_virtual(&result,
1893 threadObj, thread_klass,
1894 vmSymbols::exit_method_name(),
1895 vmSymbols::void_method_signature(),
1896 THREAD);
1897 CLEAR_PENDING_EXCEPTION;
1898 }
1899 }
1900 // notify JVMTI
1901 if (JvmtiExport::should_post_thread_life()) {
1902 JvmtiExport::post_thread_end(this);
1903 }
1904
1905 // We have notified the agents that we are exiting, before we go on,
1906 // we must check for a pending external suspend request and honor it
1907 // in order to not surprise the thread that made the suspend request.
1908 while (true) {
1909 {
1910 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1911 if (!is_external_suspend()) {
1912 set_terminated(_thread_exiting);
1913 ThreadService::current_thread_exiting(this);
1914 break;
1915 }
1916 // Implied else:
1917 // Things get a little tricky here. We have a pending external
1918 // suspend request, but we are holding the SR_lock so we
1919 // can't just self-suspend. So we temporarily drop the lock
1920 // and then self-suspend.
1921 }
1922
1923 ThreadBlockInVM tbivm(this);
1924 java_suspend_self();
1925
1926 // We're done with this suspend request, but we have to loop around
1927 // and check again. Eventually we will get SR_lock without a pending
1928 // external suspend request and will be able to mark ourselves as
1929 // exiting.
1930 }
1931 // no more external suspends are allowed at this point
1932 } else {
1933 // before_exit() has already posted JVMTI THREAD_END events
1934 }
1935
1936 if (log_is_enabled(Debug, os, thread, timer)) {
1937 _timer_exit_phase1.stop();
1938 _timer_exit_phase2.start();
1939 }
1940 // Notify waiters on thread object. This has to be done after exit() is called
1941 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1942 // group should have the destroyed bit set before waiters are notified).
1943 ensure_join(this);
1944 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1945
1946 if (log_is_enabled(Debug, os, thread, timer)) {
1947 _timer_exit_phase2.stop();
1948 _timer_exit_phase3.start();
1949 }
1950 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1951 // held by this thread must be released. The spec does not distinguish
1952 // between JNI-acquired and regular Java monitors. We can only see
1953 // regular Java monitors here if monitor enter-exit matching is broken.
1954 //
1955 // Optionally release any monitors for regular JavaThread exits. This
1956 // is provided as a work around for any bugs in monitor enter-exit
1957 // matching. This can be expensive so it is not enabled by default.
1958 //
1959 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1960 // ObjectSynchronizer::release_monitors_owned_by_thread().
1961 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1962 // Sanity check even though JNI DetachCurrentThread() would have
1963 // returned JNI_ERR if there was a Java frame. JavaThread exit
1964 // should be done executing Java code by the time we get here.
1965 assert(!this->has_last_Java_frame(),
1966 "should not have a Java frame when detaching or exiting");
1967 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1968 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1969 }
1970
1971 // These things needs to be done while we are still a Java Thread. Make sure that thread
1972 // is in a consistent state, in case GC happens
1973 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1974
1975 if (active_handles() != NULL) {
1976 JNIHandleBlock* block = active_handles();
1977 set_active_handles(NULL);
1978 JNIHandleBlock::release_block(block);
1979 }
1980
1981 if (free_handle_block() != NULL) {
1982 JNIHandleBlock* block = free_handle_block();
1983 set_free_handle_block(NULL);
1984 JNIHandleBlock::release_block(block);
1985 }
1986
1987 // These have to be removed while this is still a valid thread.
1988 remove_stack_guard_pages();
1989
1990 if (UseTLAB) {
1991 tlab().make_parsable(true); // retire TLAB
1992 }
1993
1994 if (JvmtiEnv::environments_might_exist()) {
1995 JvmtiExport::cleanup_thread(this);
1996 }
1997
1998 // We must flush any deferred card marks and other various GC barrier
1999 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2000 // before removing a thread from the list of active threads.
2001 BarrierSet::barrier_set()->on_thread_detach(this);
2002
2003 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2004 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2005 os::current_thread_id());
2006
2007 if (log_is_enabled(Debug, os, thread, timer)) {
2008 _timer_exit_phase3.stop();
2009 _timer_exit_phase4.start();
2010 }
2011 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2012 Threads::remove(this);
2013
2014 if (log_is_enabled(Debug, os, thread, timer)) {
2015 _timer_exit_phase4.stop();
2016 ResourceMark rm(this);
2017 log_debug(os, thread, timer)("name='%s'"
2018 ", exit-phase1=" JLONG_FORMAT
2019 ", exit-phase2=" JLONG_FORMAT
2020 ", exit-phase3=" JLONG_FORMAT
2021 ", exit-phase4=" JLONG_FORMAT,
2022 get_thread_name(),
2023 _timer_exit_phase1.milliseconds(),
2024 _timer_exit_phase2.milliseconds(),
2025 _timer_exit_phase3.milliseconds(),
2026 _timer_exit_phase4.milliseconds());
2027 }
2028 }
2029
2030 void JavaThread::cleanup_failed_attach_current_thread() {
2031 if (active_handles() != NULL) {
2032 JNIHandleBlock* block = active_handles();
2033 set_active_handles(NULL);
2034 JNIHandleBlock::release_block(block);
2035 }
2036
2037 if (free_handle_block() != NULL) {
2038 JNIHandleBlock* block = free_handle_block();
2039 set_free_handle_block(NULL);
2040 JNIHandleBlock::release_block(block);
2041 }
2042
2043 // These have to be removed while this is still a valid thread.
2044 remove_stack_guard_pages();
2045
2046 if (UseTLAB) {
2047 tlab().make_parsable(true); // retire TLAB, if any
2048 }
2049
2050 BarrierSet::barrier_set()->on_thread_detach(this);
2051
2052 Threads::remove(this);
2053 this->smr_delete();
2054 }
2055
2056 JavaThread* JavaThread::active() {
2057 Thread* thread = Thread::current();
2058 if (thread->is_Java_thread()) {
2059 return (JavaThread*) thread;
2060 } else {
2061 assert(thread->is_VM_thread(), "this must be a vm thread");
2062 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2063 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2064 assert(ret->is_Java_thread(), "must be a Java thread");
2065 return ret;
2066 }
2067 }
2068
2069 bool JavaThread::is_lock_owned(address adr) const {
2070 if (Thread::is_lock_owned(adr)) return true;
2071
2072 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2073 if (chunk->contains(adr)) return true;
2074 }
2075
2076 return false;
2077 }
2078
2079
2080 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2081 chunk->set_next(monitor_chunks());
2082 set_monitor_chunks(chunk);
2083 }
2084
2085 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2086 guarantee(monitor_chunks() != NULL, "must be non empty");
2087 if (monitor_chunks() == chunk) {
2088 set_monitor_chunks(chunk->next());
2089 } else {
2090 MonitorChunk* prev = monitor_chunks();
2091 while (prev->next() != chunk) prev = prev->next();
2092 prev->set_next(chunk->next());
2093 }
2094 }
2095
2096 // JVM support.
2097
2098 // Note: this function shouldn't block if it's called in
2099 // _thread_in_native_trans state (such as from
2100 // check_special_condition_for_native_trans()).
2101 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2102
2103 if (has_last_Java_frame() && has_async_condition()) {
2104 // If we are at a polling page safepoint (not a poll return)
2105 // then we must defer async exception because live registers
2106 // will be clobbered by the exception path. Poll return is
2107 // ok because the call we a returning from already collides
2108 // with exception handling registers and so there is no issue.
2109 // (The exception handling path kills call result registers but
2110 // this is ok since the exception kills the result anyway).
2111
2112 if (is_at_poll_safepoint()) {
2113 // if the code we are returning to has deoptimized we must defer
2114 // the exception otherwise live registers get clobbered on the
2115 // exception path before deoptimization is able to retrieve them.
2116 //
2117 RegisterMap map(this, false);
2118 frame caller_fr = last_frame().sender(&map);
2119 assert(caller_fr.is_compiled_frame(), "what?");
2120 if (caller_fr.is_deoptimized_frame()) {
2121 log_info(exceptions)("deferred async exception at compiled safepoint");
2122 return;
2123 }
2124 }
2125 }
2126
2127 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2128 if (condition == _no_async_condition) {
2129 // Conditions have changed since has_special_runtime_exit_condition()
2130 // was called:
2131 // - if we were here only because of an external suspend request,
2132 // then that was taken care of above (or cancelled) so we are done
2133 // - if we were here because of another async request, then it has
2134 // been cleared between the has_special_runtime_exit_condition()
2135 // and now so again we are done
2136 return;
2137 }
2138
2139 // Check for pending async. exception
2140 if (_pending_async_exception != NULL) {
2141 // Only overwrite an already pending exception, if it is not a threadDeath.
2142 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2143
2144 // We cannot call Exceptions::_throw(...) here because we cannot block
2145 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2146
2147 LogTarget(Info, exceptions) lt;
2148 if (lt.is_enabled()) {
2149 ResourceMark rm;
2150 LogStream ls(lt);
2151 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2152 if (has_last_Java_frame()) {
2153 frame f = last_frame();
2154 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2155 }
2156 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2157 }
2158 _pending_async_exception = NULL;
2159 clear_has_async_exception();
2160 }
2161 }
2162
2163 if (check_unsafe_error &&
2164 condition == _async_unsafe_access_error && !has_pending_exception()) {
2165 condition = _no_async_condition; // done
2166 switch (thread_state()) {
2167 case _thread_in_vm: {
2168 JavaThread* THREAD = this;
2169 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2170 }
2171 case _thread_in_native: {
2172 ThreadInVMfromNative tiv(this);
2173 JavaThread* THREAD = this;
2174 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2175 }
2176 case _thread_in_Java: {
2177 ThreadInVMfromJava tiv(this);
2178 JavaThread* THREAD = this;
2179 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2180 }
2181 default:
2182 ShouldNotReachHere();
2183 }
2184 }
2185
2186 assert(condition == _no_async_condition || has_pending_exception() ||
2187 (!check_unsafe_error && condition == _async_unsafe_access_error),
2188 "must have handled the async condition, if no exception");
2189 }
2190
2191 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2192 //
2193 // Check for pending external suspend. Internal suspend requests do
2194 // not use handle_special_runtime_exit_condition().
2195 // If JNIEnv proxies are allowed, don't self-suspend if the target
2196 // thread is not the current thread. In older versions of jdbx, jdbx
2197 // threads could call into the VM with another thread's JNIEnv so we
2198 // can be here operating on behalf of a suspended thread (4432884).
2199 bool do_self_suspend = is_external_suspend_with_lock();
2200 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2201 //
2202 // Because thread is external suspended the safepoint code will count
2203 // thread as at a safepoint. This can be odd because we can be here
2204 // as _thread_in_Java which would normally transition to _thread_blocked
2205 // at a safepoint. We would like to mark the thread as _thread_blocked
2206 // before calling java_suspend_self like all other callers of it but
2207 // we must then observe proper safepoint protocol. (We can't leave
2208 // _thread_blocked with a safepoint in progress). However we can be
2209 // here as _thread_in_native_trans so we can't use a normal transition
2210 // constructor/destructor pair because they assert on that type of
2211 // transition. We could do something like:
2212 //
2213 // JavaThreadState state = thread_state();
2214 // set_thread_state(_thread_in_vm);
2215 // {
2216 // ThreadBlockInVM tbivm(this);
2217 // java_suspend_self()
2218 // }
2219 // set_thread_state(_thread_in_vm_trans);
2220 // if (safepoint) block;
2221 // set_thread_state(state);
2222 //
2223 // but that is pretty messy. Instead we just go with the way the
2224 // code has worked before and note that this is the only path to
2225 // java_suspend_self that doesn't put the thread in _thread_blocked
2226 // mode.
2227
2228 frame_anchor()->make_walkable(this);
2229 java_suspend_self();
2230
2231 // We might be here for reasons in addition to the self-suspend request
2232 // so check for other async requests.
2233 }
2234
2235 if (check_asyncs) {
2236 check_and_handle_async_exceptions();
2237 }
2238 #if INCLUDE_TRACE
2239 if (is_trace_suspend()) {
2240 TRACE_SUSPEND_THREAD(this);
2241 }
2242 #endif
2243 }
2244
2245 void JavaThread::send_thread_stop(oop java_throwable) {
2246 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2247 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2248 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2249
2250 // Do not throw asynchronous exceptions against the compiler thread
2251 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2252 if (!can_call_java()) return;
2253
2254 {
2255 // Actually throw the Throwable against the target Thread - however
2256 // only if there is no thread death exception installed already.
2257 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2258 // If the topmost frame is a runtime stub, then we are calling into
2259 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2260 // must deoptimize the caller before continuing, as the compiled exception handler table
2261 // may not be valid
2262 if (has_last_Java_frame()) {
2263 frame f = last_frame();
2264 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2265 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2266 RegisterMap reg_map(this, UseBiasedLocking);
2267 frame compiled_frame = f.sender(®_map);
2268 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2269 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2270 }
2271 }
2272 }
2273
2274 // Set async. pending exception in thread.
2275 set_pending_async_exception(java_throwable);
2276
2277 if (log_is_enabled(Info, exceptions)) {
2278 ResourceMark rm;
2279 log_info(exceptions)("Pending Async. exception installed of type: %s",
2280 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2281 }
2282 // for AbortVMOnException flag
2283 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2284 }
2285 }
2286
2287
2288 // Interrupt thread so it will wake up from a potential wait()
2289 Thread::interrupt(this);
2290 }
2291
2292 // External suspension mechanism.
2293 //
2294 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2295 // to any VM_locks and it is at a transition
2296 // Self-suspension will happen on the transition out of the vm.
2297 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2298 //
2299 // Guarantees on return:
2300 // + Target thread will not execute any new bytecode (that's why we need to
2301 // force a safepoint)
2302 // + Target thread will not enter any new monitors
2303 //
2304 void JavaThread::java_suspend() {
2305 ThreadsListHandle tlh;
2306 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2307 return;
2308 }
2309
2310 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2311 if (!is_external_suspend()) {
2312 // a racing resume has cancelled us; bail out now
2313 return;
2314 }
2315
2316 // suspend is done
2317 uint32_t debug_bits = 0;
2318 // Warning: is_ext_suspend_completed() may temporarily drop the
2319 // SR_lock to allow the thread to reach a stable thread state if
2320 // it is currently in a transient thread state.
2321 if (is_ext_suspend_completed(false /* !called_by_wait */,
2322 SuspendRetryDelay, &debug_bits)) {
2323 return;
2324 }
2325 }
2326
2327 VM_ThreadSuspend vm_suspend;
2328 VMThread::execute(&vm_suspend);
2329 }
2330
2331 // Part II of external suspension.
2332 // A JavaThread self suspends when it detects a pending external suspend
2333 // request. This is usually on transitions. It is also done in places
2334 // where continuing to the next transition would surprise the caller,
2335 // e.g., monitor entry.
2336 //
2337 // Returns the number of times that the thread self-suspended.
2338 //
2339 // Note: DO NOT call java_suspend_self() when you just want to block current
2340 // thread. java_suspend_self() is the second stage of cooperative
2341 // suspension for external suspend requests and should only be used
2342 // to complete an external suspend request.
2343 //
2344 int JavaThread::java_suspend_self() {
2345 int ret = 0;
2346
2347 // we are in the process of exiting so don't suspend
2348 if (is_exiting()) {
2349 clear_external_suspend();
2350 return ret;
2351 }
2352
2353 assert(_anchor.walkable() ||
2354 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2355 "must have walkable stack");
2356
2357 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2358
2359 assert(!this->is_ext_suspended(),
2360 "a thread trying to self-suspend should not already be suspended");
2361
2362 if (this->is_suspend_equivalent()) {
2363 // If we are self-suspending as a result of the lifting of a
2364 // suspend equivalent condition, then the suspend_equivalent
2365 // flag is not cleared until we set the ext_suspended flag so
2366 // that wait_for_ext_suspend_completion() returns consistent
2367 // results.
2368 this->clear_suspend_equivalent();
2369 }
2370
2371 // A racing resume may have cancelled us before we grabbed SR_lock
2372 // above. Or another external suspend request could be waiting for us
2373 // by the time we return from SR_lock()->wait(). The thread
2374 // that requested the suspension may already be trying to walk our
2375 // stack and if we return now, we can change the stack out from under
2376 // it. This would be a "bad thing (TM)" and cause the stack walker
2377 // to crash. We stay self-suspended until there are no more pending
2378 // external suspend requests.
2379 while (is_external_suspend()) {
2380 ret++;
2381 this->set_ext_suspended();
2382
2383 // _ext_suspended flag is cleared by java_resume()
2384 while (is_ext_suspended()) {
2385 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2386 }
2387 }
2388
2389 return ret;
2390 }
2391
2392 #ifdef ASSERT
2393 // verify the JavaThread has not yet been published in the Threads::list, and
2394 // hence doesn't need protection from concurrent access at this stage
2395 void JavaThread::verify_not_published() {
2396 ThreadsListHandle tlh;
2397 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2398 }
2399 #endif
2400
2401 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2402 // progress or when _suspend_flags is non-zero.
2403 // Current thread needs to self-suspend if there is a suspend request and/or
2404 // block if a safepoint is in progress.
2405 // Async exception ISN'T checked.
2406 // Note only the ThreadInVMfromNative transition can call this function
2407 // directly and when thread state is _thread_in_native_trans
2408 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2409 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2410
2411 JavaThread *curJT = JavaThread::current();
2412 bool do_self_suspend = thread->is_external_suspend();
2413
2414 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2415
2416 // If JNIEnv proxies are allowed, don't self-suspend if the target
2417 // thread is not the current thread. In older versions of jdbx, jdbx
2418 // threads could call into the VM with another thread's JNIEnv so we
2419 // can be here operating on behalf of a suspended thread (4432884).
2420 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2421 JavaThreadState state = thread->thread_state();
2422
2423 // We mark this thread_blocked state as a suspend-equivalent so
2424 // that a caller to is_ext_suspend_completed() won't be confused.
2425 // The suspend-equivalent state is cleared by java_suspend_self().
2426 thread->set_suspend_equivalent();
2427
2428 // If the safepoint code sees the _thread_in_native_trans state, it will
2429 // wait until the thread changes to other thread state. There is no
2430 // guarantee on how soon we can obtain the SR_lock and complete the
2431 // self-suspend request. It would be a bad idea to let safepoint wait for
2432 // too long. Temporarily change the state to _thread_blocked to
2433 // let the VM thread know that this thread is ready for GC. The problem
2434 // of changing thread state is that safepoint could happen just after
2435 // java_suspend_self() returns after being resumed, and VM thread will
2436 // see the _thread_blocked state. We must check for safepoint
2437 // after restoring the state and make sure we won't leave while a safepoint
2438 // is in progress.
2439 thread->set_thread_state(_thread_blocked);
2440 thread->java_suspend_self();
2441 thread->set_thread_state(state);
2442
2443 InterfaceSupport::serialize_thread_state_with_handler(thread);
2444 }
2445
2446 SafepointMechanism::block_if_requested(curJT);
2447
2448 if (thread->is_deopt_suspend()) {
2449 thread->clear_deopt_suspend();
2450 RegisterMap map(thread, false);
2451 frame f = thread->last_frame();
2452 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2453 f = f.sender(&map);
2454 }
2455 if (f.id() == thread->must_deopt_id()) {
2456 thread->clear_must_deopt_id();
2457 f.deoptimize(thread);
2458 } else {
2459 fatal("missed deoptimization!");
2460 }
2461 }
2462 #if INCLUDE_TRACE
2463 if (thread->is_trace_suspend()) {
2464 TRACE_SUSPEND_THREAD(thread);
2465 }
2466 #endif
2467 }
2468
2469 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2470 // progress or when _suspend_flags is non-zero.
2471 // Current thread needs to self-suspend if there is a suspend request and/or
2472 // block if a safepoint is in progress.
2473 // Also check for pending async exception (not including unsafe access error).
2474 // Note only the native==>VM/Java barriers can call this function and when
2475 // thread state is _thread_in_native_trans.
2476 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2477 check_safepoint_and_suspend_for_native_trans(thread);
2478
2479 if (thread->has_async_exception()) {
2480 // We are in _thread_in_native_trans state, don't handle unsafe
2481 // access error since that may block.
2482 thread->check_and_handle_async_exceptions(false);
2483 }
2484 }
2485
2486 // This is a variant of the normal
2487 // check_special_condition_for_native_trans with slightly different
2488 // semantics for use by critical native wrappers. It does all the
2489 // normal checks but also performs the transition back into
2490 // thread_in_Java state. This is required so that critical natives
2491 // can potentially block and perform a GC if they are the last thread
2492 // exiting the GCLocker.
2493 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2494 check_special_condition_for_native_trans(thread);
2495
2496 // Finish the transition
2497 thread->set_thread_state(_thread_in_Java);
2498
2499 if (thread->do_critical_native_unlock()) {
2500 ThreadInVMfromJavaNoAsyncException tiv(thread);
2501 GCLocker::unlock_critical(thread);
2502 thread->clear_critical_native_unlock();
2503 }
2504 }
2505
2506 // We need to guarantee the Threads_lock here, since resumes are not
2507 // allowed during safepoint synchronization
2508 // Can only resume from an external suspension
2509 void JavaThread::java_resume() {
2510 assert_locked_or_safepoint(Threads_lock);
2511
2512 // Sanity check: thread is gone, has started exiting or the thread
2513 // was not externally suspended.
2514 ThreadsListHandle tlh;
2515 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2516 return;
2517 }
2518
2519 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2520
2521 clear_external_suspend();
2522
2523 if (is_ext_suspended()) {
2524 clear_ext_suspended();
2525 SR_lock()->notify_all();
2526 }
2527 }
2528
2529 size_t JavaThread::_stack_red_zone_size = 0;
2530 size_t JavaThread::_stack_yellow_zone_size = 0;
2531 size_t JavaThread::_stack_reserved_zone_size = 0;
2532 size_t JavaThread::_stack_shadow_zone_size = 0;
2533
2534 void JavaThread::create_stack_guard_pages() {
2535 if (!os::uses_stack_guard_pages() ||
2536 _stack_guard_state != stack_guard_unused ||
2537 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2538 log_info(os, thread)("Stack guard page creation for thread "
2539 UINTX_FORMAT " disabled", os::current_thread_id());
2540 return;
2541 }
2542 address low_addr = stack_end();
2543 size_t len = stack_guard_zone_size();
2544
2545 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2546 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2547
2548 int must_commit = os::must_commit_stack_guard_pages();
2549 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2550
2551 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2552 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2553 return;
2554 }
2555
2556 if (os::guard_memory((char *) low_addr, len)) {
2557 _stack_guard_state = stack_guard_enabled;
2558 } else {
2559 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2560 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2561 if (os::uncommit_memory((char *) low_addr, len)) {
2562 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2563 }
2564 return;
2565 }
2566
2567 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2568 PTR_FORMAT "-" PTR_FORMAT ".",
2569 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2570 }
2571
2572 void JavaThread::remove_stack_guard_pages() {
2573 assert(Thread::current() == this, "from different thread");
2574 if (_stack_guard_state == stack_guard_unused) return;
2575 address low_addr = stack_end();
2576 size_t len = stack_guard_zone_size();
2577
2578 if (os::must_commit_stack_guard_pages()) {
2579 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2580 _stack_guard_state = stack_guard_unused;
2581 } else {
2582 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2583 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2584 return;
2585 }
2586 } else {
2587 if (_stack_guard_state == stack_guard_unused) return;
2588 if (os::unguard_memory((char *) low_addr, len)) {
2589 _stack_guard_state = stack_guard_unused;
2590 } else {
2591 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2592 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2593 return;
2594 }
2595 }
2596
2597 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2598 PTR_FORMAT "-" PTR_FORMAT ".",
2599 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2600 }
2601
2602 void JavaThread::enable_stack_reserved_zone() {
2603 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2604 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2605
2606 // The base notation is from the stack's point of view, growing downward.
2607 // We need to adjust it to work correctly with guard_memory()
2608 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2609
2610 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2611 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2612
2613 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2614 _stack_guard_state = stack_guard_enabled;
2615 } else {
2616 warning("Attempt to guard stack reserved zone failed.");
2617 }
2618 enable_register_stack_guard();
2619 }
2620
2621 void JavaThread::disable_stack_reserved_zone() {
2622 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2623 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2624
2625 // Simply return if called for a thread that does not use guard pages.
2626 if (_stack_guard_state == stack_guard_unused) return;
2627
2628 // The base notation is from the stack's point of view, growing downward.
2629 // We need to adjust it to work correctly with guard_memory()
2630 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2631
2632 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2633 _stack_guard_state = stack_guard_reserved_disabled;
2634 } else {
2635 warning("Attempt to unguard stack reserved zone failed.");
2636 }
2637 disable_register_stack_guard();
2638 }
2639
2640 void JavaThread::enable_stack_yellow_reserved_zone() {
2641 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2642 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2643
2644 // The base notation is from the stacks point of view, growing downward.
2645 // We need to adjust it to work correctly with guard_memory()
2646 address base = stack_red_zone_base();
2647
2648 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2649 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2650
2651 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2652 _stack_guard_state = stack_guard_enabled;
2653 } else {
2654 warning("Attempt to guard stack yellow zone failed.");
2655 }
2656 enable_register_stack_guard();
2657 }
2658
2659 void JavaThread::disable_stack_yellow_reserved_zone() {
2660 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2661 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2662
2663 // Simply return if called for a thread that does not use guard pages.
2664 if (_stack_guard_state == stack_guard_unused) return;
2665
2666 // The base notation is from the stacks point of view, growing downward.
2667 // We need to adjust it to work correctly with guard_memory()
2668 address base = stack_red_zone_base();
2669
2670 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2671 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2672 } else {
2673 warning("Attempt to unguard stack yellow zone failed.");
2674 }
2675 disable_register_stack_guard();
2676 }
2677
2678 void JavaThread::enable_stack_red_zone() {
2679 // The base notation is from the stacks point of view, growing downward.
2680 // We need to adjust it to work correctly with guard_memory()
2681 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2682 address base = stack_red_zone_base() - stack_red_zone_size();
2683
2684 guarantee(base < stack_base(), "Error calculating stack red zone");
2685 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2686
2687 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2688 warning("Attempt to guard stack red zone failed.");
2689 }
2690 }
2691
2692 void JavaThread::disable_stack_red_zone() {
2693 // The base notation is from the stacks point of view, growing downward.
2694 // We need to adjust it to work correctly with guard_memory()
2695 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2696 address base = stack_red_zone_base() - stack_red_zone_size();
2697 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2698 warning("Attempt to unguard stack red zone failed.");
2699 }
2700 }
2701
2702 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2703 // ignore is there is no stack
2704 if (!has_last_Java_frame()) return;
2705 // traverse the stack frames. Starts from top frame.
2706 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2707 frame* fr = fst.current();
2708 f(fr, fst.register_map());
2709 }
2710 }
2711
2712
2713 #ifndef PRODUCT
2714 // Deoptimization
2715 // Function for testing deoptimization
2716 void JavaThread::deoptimize() {
2717 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2718 StackFrameStream fst(this, UseBiasedLocking);
2719 bool deopt = false; // Dump stack only if a deopt actually happens.
2720 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2721 // Iterate over all frames in the thread and deoptimize
2722 for (; !fst.is_done(); fst.next()) {
2723 if (fst.current()->can_be_deoptimized()) {
2724
2725 if (only_at) {
2726 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2727 // consists of comma or carriage return separated numbers so
2728 // search for the current bci in that string.
2729 address pc = fst.current()->pc();
2730 nmethod* nm = (nmethod*) fst.current()->cb();
2731 ScopeDesc* sd = nm->scope_desc_at(pc);
2732 char buffer[8];
2733 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2734 size_t len = strlen(buffer);
2735 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2736 while (found != NULL) {
2737 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2738 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2739 // Check that the bci found is bracketed by terminators.
2740 break;
2741 }
2742 found = strstr(found + 1, buffer);
2743 }
2744 if (!found) {
2745 continue;
2746 }
2747 }
2748
2749 if (DebugDeoptimization && !deopt) {
2750 deopt = true; // One-time only print before deopt
2751 tty->print_cr("[BEFORE Deoptimization]");
2752 trace_frames();
2753 trace_stack();
2754 }
2755 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2756 }
2757 }
2758
2759 if (DebugDeoptimization && deopt) {
2760 tty->print_cr("[AFTER Deoptimization]");
2761 trace_frames();
2762 }
2763 }
2764
2765
2766 // Make zombies
2767 void JavaThread::make_zombies() {
2768 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2769 if (fst.current()->can_be_deoptimized()) {
2770 // it is a Java nmethod
2771 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2772 nm->make_not_entrant();
2773 }
2774 }
2775 }
2776 #endif // PRODUCT
2777
2778
2779 void JavaThread::deoptimized_wrt_marked_nmethods() {
2780 if (!has_last_Java_frame()) return;
2781 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2782 StackFrameStream fst(this, UseBiasedLocking);
2783 for (; !fst.is_done(); fst.next()) {
2784 if (fst.current()->should_be_deoptimized()) {
2785 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2786 }
2787 }
2788 }
2789
2790
2791 // If the caller is a NamedThread, then remember, in the current scope,
2792 // the given JavaThread in its _processed_thread field.
2793 class RememberProcessedThread: public StackObj {
2794 NamedThread* _cur_thr;
2795 public:
2796 RememberProcessedThread(JavaThread* jthr) {
2797 Thread* thread = Thread::current();
2798 if (thread->is_Named_thread()) {
2799 _cur_thr = (NamedThread *)thread;
2800 _cur_thr->set_processed_thread(jthr);
2801 } else {
2802 _cur_thr = NULL;
2803 }
2804 }
2805
2806 ~RememberProcessedThread() {
2807 if (_cur_thr) {
2808 _cur_thr->set_processed_thread(NULL);
2809 }
2810 }
2811 };
2812
2813 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2814 // Verify that the deferred card marks have been flushed.
2815 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2816
2817 // Traverse the GCHandles
2818 Thread::oops_do(f, cf);
2819
2820 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2821
2822 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2823 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2824
2825 if (has_last_Java_frame()) {
2826 // Record JavaThread to GC thread
2827 RememberProcessedThread rpt(this);
2828
2829 // Traverse the privileged stack
2830 if (_privileged_stack_top != NULL) {
2831 _privileged_stack_top->oops_do(f);
2832 }
2833
2834 // traverse the registered growable array
2835 if (_array_for_gc != NULL) {
2836 for (int index = 0; index < _array_for_gc->length(); index++) {
2837 f->do_oop(_array_for_gc->adr_at(index));
2838 }
2839 }
2840
2841 // Traverse the monitor chunks
2842 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2843 chunk->oops_do(f);
2844 }
2845
2846 // Traverse the execution stack
2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848 fst.current()->oops_do(f, cf, fst.register_map());
2849 }
2850 }
2851
2852 // callee_target is never live across a gc point so NULL it here should
2853 // it still contain a methdOop.
2854
2855 set_callee_target(NULL);
2856
2857 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2858 // If we have deferred set_locals there might be oops waiting to be
2859 // written
2860 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2861 if (list != NULL) {
2862 for (int i = 0; i < list->length(); i++) {
2863 list->at(i)->oops_do(f);
2864 }
2865 }
2866
2867 // Traverse instance variables at the end since the GC may be moving things
2868 // around using this function
2869 f->do_oop((oop*) &_threadObj);
2870 f->do_oop((oop*) &_vm_result);
2871 f->do_oop((oop*) &_exception_oop);
2872 f->do_oop((oop*) &_pending_async_exception);
2873
2874 if (jvmti_thread_state() != NULL) {
2875 jvmti_thread_state()->oops_do(f);
2876 }
2877 }
2878
2879 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2880 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2881 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2882
2883 if (has_last_Java_frame()) {
2884 // Traverse the execution stack
2885 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2886 fst.current()->nmethods_do(cf);
2887 }
2888 }
2889 }
2890
2891 void JavaThread::metadata_do(void f(Metadata*)) {
2892 if (has_last_Java_frame()) {
2893 // Traverse the execution stack to call f() on the methods in the stack
2894 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2895 fst.current()->metadata_do(f);
2896 }
2897 } else if (is_Compiler_thread()) {
2898 // need to walk ciMetadata in current compile tasks to keep alive.
2899 CompilerThread* ct = (CompilerThread*)this;
2900 if (ct->env() != NULL) {
2901 ct->env()->metadata_do(f);
2902 }
2903 CompileTask* task = ct->task();
2904 if (task != NULL) {
2905 task->metadata_do(f);
2906 }
2907 }
2908 }
2909
2910 // Printing
2911 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2912 switch (_thread_state) {
2913 case _thread_uninitialized: return "_thread_uninitialized";
2914 case _thread_new: return "_thread_new";
2915 case _thread_new_trans: return "_thread_new_trans";
2916 case _thread_in_native: return "_thread_in_native";
2917 case _thread_in_native_trans: return "_thread_in_native_trans";
2918 case _thread_in_vm: return "_thread_in_vm";
2919 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2920 case _thread_in_Java: return "_thread_in_Java";
2921 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2922 case _thread_blocked: return "_thread_blocked";
2923 case _thread_blocked_trans: return "_thread_blocked_trans";
2924 default: return "unknown thread state";
2925 }
2926 }
2927
2928 #ifndef PRODUCT
2929 void JavaThread::print_thread_state_on(outputStream *st) const {
2930 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2931 };
2932 void JavaThread::print_thread_state() const {
2933 print_thread_state_on(tty);
2934 }
2935 #endif // PRODUCT
2936
2937 // Called by Threads::print() for VM_PrintThreads operation
2938 void JavaThread::print_on(outputStream *st) const {
2939 st->print_raw("\"");
2940 st->print_raw(get_thread_name());
2941 st->print_raw("\" ");
2942 oop thread_oop = threadObj();
2943 if (thread_oop != NULL) {
2944 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2945 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2946 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2947 }
2948 Thread::print_on(st);
2949 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2950 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2951 if (thread_oop != NULL) {
2952 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2953 }
2954 #ifndef PRODUCT
2955 print_thread_state_on(st);
2956 _safepoint_state->print_on(st);
2957 #endif // PRODUCT
2958 if (is_Compiler_thread()) {
2959 CompileTask *task = ((CompilerThread*)this)->task();
2960 if (task != NULL) {
2961 st->print(" Compiling: ");
2962 task->print(st, NULL, true, false);
2963 } else {
2964 st->print(" No compile task");
2965 }
2966 st->cr();
2967 }
2968 }
2969
2970 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2971 st->print("%s", get_thread_name_string(buf, buflen));
2972 }
2973
2974 // Called by fatal error handler. The difference between this and
2975 // JavaThread::print() is that we can't grab lock or allocate memory.
2976 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2977 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2978 oop thread_obj = threadObj();
2979 if (thread_obj != NULL) {
2980 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2981 }
2982 st->print(" [");
2983 st->print("%s", _get_thread_state_name(_thread_state));
2984 if (osthread()) {
2985 st->print(", id=%d", osthread()->thread_id());
2986 }
2987 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2988 p2i(stack_end()), p2i(stack_base()));
2989 st->print("]");
2990
2991 if (_threads_hazard_ptr != NULL) {
2992 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2993 }
2994 if (_nested_threads_hazard_ptr != NULL) {
2995 print_nested_threads_hazard_ptrs_on(st);
2996 }
2997 return;
2998 }
2999
3000 // Verification
3001
3002 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3003
3004 void JavaThread::verify() {
3005 // Verify oops in the thread.
3006 oops_do(&VerifyOopClosure::verify_oop, NULL);
3007
3008 // Verify the stack frames.
3009 frames_do(frame_verify);
3010 }
3011
3012 // CR 6300358 (sub-CR 2137150)
3013 // Most callers of this method assume that it can't return NULL but a
3014 // thread may not have a name whilst it is in the process of attaching to
3015 // the VM - see CR 6412693, and there are places where a JavaThread can be
3016 // seen prior to having it's threadObj set (eg JNI attaching threads and
3017 // if vm exit occurs during initialization). These cases can all be accounted
3018 // for such that this method never returns NULL.
3019 const char* JavaThread::get_thread_name() const {
3020 #ifdef ASSERT
3021 // early safepoints can hit while current thread does not yet have TLS
3022 if (!SafepointSynchronize::is_at_safepoint()) {
3023 Thread *cur = Thread::current();
3024 if (!(cur->is_Java_thread() && cur == this)) {
3025 // Current JavaThreads are allowed to get their own name without
3026 // the Threads_lock.
3027 assert_locked_or_safepoint(Threads_lock);
3028 }
3029 }
3030 #endif // ASSERT
3031 return get_thread_name_string();
3032 }
3033
3034 // Returns a non-NULL representation of this thread's name, or a suitable
3035 // descriptive string if there is no set name
3036 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3037 const char* name_str;
3038 oop thread_obj = threadObj();
3039 if (thread_obj != NULL) {
3040 oop name = java_lang_Thread::name(thread_obj);
3041 if (name != NULL) {
3042 if (buf == NULL) {
3043 name_str = java_lang_String::as_utf8_string(name);
3044 } else {
3045 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3046 }
3047 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3048 name_str = "<no-name - thread is attaching>";
3049 } else {
3050 name_str = Thread::name();
3051 }
3052 } else {
3053 name_str = Thread::name();
3054 }
3055 assert(name_str != NULL, "unexpected NULL thread name");
3056 return name_str;
3057 }
3058
3059
3060 const char* JavaThread::get_threadgroup_name() const {
3061 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3062 oop thread_obj = threadObj();
3063 if (thread_obj != NULL) {
3064 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3065 if (thread_group != NULL) {
3066 // ThreadGroup.name can be null
3067 return java_lang_ThreadGroup::name(thread_group);
3068 }
3069 }
3070 return NULL;
3071 }
3072
3073 const char* JavaThread::get_parent_name() const {
3074 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3075 oop thread_obj = threadObj();
3076 if (thread_obj != NULL) {
3077 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3078 if (thread_group != NULL) {
3079 oop parent = java_lang_ThreadGroup::parent(thread_group);
3080 if (parent != NULL) {
3081 // ThreadGroup.name can be null
3082 return java_lang_ThreadGroup::name(parent);
3083 }
3084 }
3085 }
3086 return NULL;
3087 }
3088
3089 ThreadPriority JavaThread::java_priority() const {
3090 oop thr_oop = threadObj();
3091 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3092 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3093 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3094 return priority;
3095 }
3096
3097 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3098
3099 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3100 // Link Java Thread object <-> C++ Thread
3101
3102 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3103 // and put it into a new Handle. The Handle "thread_oop" can then
3104 // be used to pass the C++ thread object to other methods.
3105
3106 // Set the Java level thread object (jthread) field of the
3107 // new thread (a JavaThread *) to C++ thread object using the
3108 // "thread_oop" handle.
3109
3110 // Set the thread field (a JavaThread *) of the
3111 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3112
3113 Handle thread_oop(Thread::current(),
3114 JNIHandles::resolve_non_null(jni_thread));
3115 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3116 "must be initialized");
3117 set_threadObj(thread_oop());
3118 java_lang_Thread::set_thread(thread_oop(), this);
3119
3120 if (prio == NoPriority) {
3121 prio = java_lang_Thread::priority(thread_oop());
3122 assert(prio != NoPriority, "A valid priority should be present");
3123 }
3124
3125 // Push the Java priority down to the native thread; needs Threads_lock
3126 Thread::set_priority(this, prio);
3127
3128 prepare_ext();
3129
3130 // Add the new thread to the Threads list and set it in motion.
3131 // We must have threads lock in order to call Threads::add.
3132 // It is crucial that we do not block before the thread is
3133 // added to the Threads list for if a GC happens, then the java_thread oop
3134 // will not be visited by GC.
3135 Threads::add(this);
3136 }
3137
3138 oop JavaThread::current_park_blocker() {
3139 // Support for JSR-166 locks
3140 oop thread_oop = threadObj();
3141 if (thread_oop != NULL &&
3142 JDK_Version::current().supports_thread_park_blocker()) {
3143 return java_lang_Thread::park_blocker(thread_oop);
3144 }
3145 return NULL;
3146 }
3147
3148
3149 void JavaThread::print_stack_on(outputStream* st) {
3150 if (!has_last_Java_frame()) return;
3151 ResourceMark rm;
3152 HandleMark hm;
3153
3154 RegisterMap reg_map(this);
3155 vframe* start_vf = last_java_vframe(®_map);
3156 int count = 0;
3157 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3158 if (f->is_java_frame()) {
3159 javaVFrame* jvf = javaVFrame::cast(f);
3160 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3161
3162 // Print out lock information
3163 if (JavaMonitorsInStackTrace) {
3164 jvf->print_lock_info_on(st, count);
3165 }
3166 } else {
3167 // Ignore non-Java frames
3168 }
3169
3170 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3171 count++;
3172 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3173 }
3174 }
3175
3176
3177 // JVMTI PopFrame support
3178 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3179 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3180 if (in_bytes(size_in_bytes) != 0) {
3181 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3182 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3183 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3184 }
3185 }
3186
3187 void* JavaThread::popframe_preserved_args() {
3188 return _popframe_preserved_args;
3189 }
3190
3191 ByteSize JavaThread::popframe_preserved_args_size() {
3192 return in_ByteSize(_popframe_preserved_args_size);
3193 }
3194
3195 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3196 int sz = in_bytes(popframe_preserved_args_size());
3197 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3198 return in_WordSize(sz / wordSize);
3199 }
3200
3201 void JavaThread::popframe_free_preserved_args() {
3202 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3203 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3204 _popframe_preserved_args = NULL;
3205 _popframe_preserved_args_size = 0;
3206 }
3207
3208 #ifndef PRODUCT
3209
3210 void JavaThread::trace_frames() {
3211 tty->print_cr("[Describe stack]");
3212 int frame_no = 1;
3213 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3214 tty->print(" %d. ", frame_no++);
3215 fst.current()->print_value_on(tty, this);
3216 tty->cr();
3217 }
3218 }
3219
3220 class PrintAndVerifyOopClosure: public OopClosure {
3221 protected:
3222 template <class T> inline void do_oop_work(T* p) {
3223 oop obj = oopDesc::load_decode_heap_oop(p);
3224 if (obj == NULL) return;
3225 tty->print(INTPTR_FORMAT ": ", p2i(p));
3226 if (oopDesc::is_oop_or_null(obj)) {
3227 if (obj->is_objArray()) {
3228 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3229 } else {
3230 obj->print();
3231 }
3232 } else {
3233 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3234 }
3235 tty->cr();
3236 }
3237 public:
3238 virtual void do_oop(oop* p) { do_oop_work(p); }
3239 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3240 };
3241
3242
3243 static void oops_print(frame* f, const RegisterMap *map) {
3244 PrintAndVerifyOopClosure print;
3245 f->print_value();
3246 f->oops_do(&print, NULL, (RegisterMap*)map);
3247 }
3248
3249 // Print our all the locations that contain oops and whether they are
3250 // valid or not. This useful when trying to find the oldest frame
3251 // where an oop has gone bad since the frame walk is from youngest to
3252 // oldest.
3253 void JavaThread::trace_oops() {
3254 tty->print_cr("[Trace oops]");
3255 frames_do(oops_print);
3256 }
3257
3258
3259 #ifdef ASSERT
3260 // Print or validate the layout of stack frames
3261 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3262 ResourceMark rm;
3263 PRESERVE_EXCEPTION_MARK;
3264 FrameValues values;
3265 int frame_no = 0;
3266 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3267 fst.current()->describe(values, ++frame_no);
3268 if (depth == frame_no) break;
3269 }
3270 if (validate_only) {
3271 values.validate();
3272 } else {
3273 tty->print_cr("[Describe stack layout]");
3274 values.print(this);
3275 }
3276 }
3277 #endif
3278
3279 void JavaThread::trace_stack_from(vframe* start_vf) {
3280 ResourceMark rm;
3281 int vframe_no = 1;
3282 for (vframe* f = start_vf; f; f = f->sender()) {
3283 if (f->is_java_frame()) {
3284 javaVFrame::cast(f)->print_activation(vframe_no++);
3285 } else {
3286 f->print();
3287 }
3288 if (vframe_no > StackPrintLimit) {
3289 tty->print_cr("...<more frames>...");
3290 return;
3291 }
3292 }
3293 }
3294
3295
3296 void JavaThread::trace_stack() {
3297 if (!has_last_Java_frame()) return;
3298 ResourceMark rm;
3299 HandleMark hm;
3300 RegisterMap reg_map(this);
3301 trace_stack_from(last_java_vframe(®_map));
3302 }
3303
3304
3305 #endif // PRODUCT
3306
3307
3308 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3309 assert(reg_map != NULL, "a map must be given");
3310 frame f = last_frame();
3311 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3312 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3313 }
3314 return NULL;
3315 }
3316
3317
3318 Klass* JavaThread::security_get_caller_class(int depth) {
3319 vframeStream vfst(this);
3320 vfst.security_get_caller_frame(depth);
3321 if (!vfst.at_end()) {
3322 return vfst.method()->method_holder();
3323 }
3324 return NULL;
3325 }
3326
3327 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3328 assert(thread->is_Compiler_thread(), "must be compiler thread");
3329 CompileBroker::compiler_thread_loop();
3330 }
3331
3332 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3333 NMethodSweeper::sweeper_loop();
3334 }
3335
3336 // Create a CompilerThread
3337 CompilerThread::CompilerThread(CompileQueue* queue,
3338 CompilerCounters* counters)
3339 : JavaThread(&compiler_thread_entry) {
3340 _env = NULL;
3341 _log = NULL;
3342 _task = NULL;
3343 _queue = queue;
3344 _counters = counters;
3345 _buffer_blob = NULL;
3346 _compiler = NULL;
3347
3348 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3349 resource_area()->bias_to(mtCompiler);
3350
3351 #ifndef PRODUCT
3352 _ideal_graph_printer = NULL;
3353 #endif
3354 }
3355
3356 bool CompilerThread::can_call_java() const {
3357 return _compiler != NULL && _compiler->is_jvmci();
3358 }
3359
3360 // Create sweeper thread
3361 CodeCacheSweeperThread::CodeCacheSweeperThread()
3362 : JavaThread(&sweeper_thread_entry) {
3363 _scanned_compiled_method = NULL;
3364 }
3365
3366 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3367 JavaThread::oops_do(f, cf);
3368 if (_scanned_compiled_method != NULL && cf != NULL) {
3369 // Safepoints can occur when the sweeper is scanning an nmethod so
3370 // process it here to make sure it isn't unloaded in the middle of
3371 // a scan.
3372 cf->do_code_blob(_scanned_compiled_method);
3373 }
3374 }
3375
3376 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3377 JavaThread::nmethods_do(cf);
3378 if (_scanned_compiled_method != NULL && cf != NULL) {
3379 // Safepoints can occur when the sweeper is scanning an nmethod so
3380 // process it here to make sure it isn't unloaded in the middle of
3381 // a scan.
3382 cf->do_code_blob(_scanned_compiled_method);
3383 }
3384 }
3385
3386
3387 // ======= Threads ========
3388
3389 // The Threads class links together all active threads, and provides
3390 // operations over all threads. It is protected by the Threads_lock,
3391 // which is also used in other global contexts like safepointing.
3392 // ThreadsListHandles are used to safely perform operations on one
3393 // or more threads without the risk of the thread exiting during the
3394 // operation.
3395 //
3396 // Note: The Threads_lock is currently more widely used than we
3397 // would like. We are actively migrating Threads_lock uses to other
3398 // mechanisms in order to reduce Threads_lock contention.
3399
3400 JavaThread* Threads::_thread_list = NULL;
3401 int Threads::_number_of_threads = 0;
3402 int Threads::_number_of_non_daemon_threads = 0;
3403 int Threads::_return_code = 0;
3404 int Threads::_thread_claim_parity = 0;
3405 size_t JavaThread::_stack_size_at_create = 0;
3406
3407 #ifdef ASSERT
3408 bool Threads::_vm_complete = false;
3409 #endif
3410
3411 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3412 Prefetch::read((void*)addr, prefetch_interval);
3413 return *addr;
3414 }
3415
3416 // Possibly the ugliest for loop the world has seen. C++ does not allow
3417 // multiple types in the declaration section of the for loop. In this case
3418 // we are only dealing with pointers and hence can cast them. It looks ugly
3419 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3420 #define DO_JAVA_THREADS(LIST, X) \
3421 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3422 *MACRO_list = (JavaThread*)(LIST), \
3423 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3424 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3425 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3426 MACRO_current_p != MACRO_end; \
3427 MACRO_current_p++, \
3428 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3429
3430 // All JavaThreads
3431 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3432
3433 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3434 void Threads::threads_do(ThreadClosure* tc) {
3435 assert_locked_or_safepoint(Threads_lock);
3436 // ALL_JAVA_THREADS iterates through all JavaThreads
3437 ALL_JAVA_THREADS(p) {
3438 tc->do_thread(p);
3439 }
3440 // Someday we could have a table or list of all non-JavaThreads.
3441 // For now, just manually iterate through them.
3442 tc->do_thread(VMThread::vm_thread());
3443 Universe::heap()->gc_threads_do(tc);
3444 WatcherThread *wt = WatcherThread::watcher_thread();
3445 // Strictly speaking, the following NULL check isn't sufficient to make sure
3446 // the data for WatcherThread is still valid upon being examined. However,
3447 // considering that WatchThread terminates when the VM is on the way to
3448 // exit at safepoint, the chance of the above is extremely small. The right
3449 // way to prevent termination of WatcherThread would be to acquire
3450 // Terminator_lock, but we can't do that without violating the lock rank
3451 // checking in some cases.
3452 if (wt != NULL) {
3453 tc->do_thread(wt);
3454 }
3455
3456 // If CompilerThreads ever become non-JavaThreads, add them here
3457 }
3458
3459 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3460 int cp = Threads::thread_claim_parity();
3461 ALL_JAVA_THREADS(p) {
3462 if (p->claim_oops_do(is_par, cp)) {
3463 tc->do_thread(p);
3464 }
3465 }
3466 VMThread* vmt = VMThread::vm_thread();
3467 if (vmt->claim_oops_do(is_par, cp)) {
3468 tc->do_thread(vmt);
3469 }
3470 }
3471
3472 // The system initialization in the library has three phases.
3473 //
3474 // Phase 1: java.lang.System class initialization
3475 // java.lang.System is a primordial class loaded and initialized
3476 // by the VM early during startup. java.lang.System.<clinit>
3477 // only does registerNatives and keeps the rest of the class
3478 // initialization work later until thread initialization completes.
3479 //
3480 // System.initPhase1 initializes the system properties, the static
3481 // fields in, out, and err. Set up java signal handlers, OS-specific
3482 // system settings, and thread group of the main thread.
3483 static void call_initPhase1(TRAPS) {
3484 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3485 JavaValue result(T_VOID);
3486 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3487 vmSymbols::void_method_signature(), CHECK);
3488 }
3489
3490 // Phase 2. Module system initialization
3491 // This will initialize the module system. Only java.base classes
3492 // can be loaded until phase 2 completes.
3493 //
3494 // Call System.initPhase2 after the compiler initialization and jsr292
3495 // classes get initialized because module initialization runs a lot of java
3496 // code, that for performance reasons, should be compiled. Also, this will
3497 // enable the startup code to use lambda and other language features in this
3498 // phase and onward.
3499 //
3500 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3501 static void call_initPhase2(TRAPS) {
3502 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3503
3504 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3505
3506 JavaValue result(T_INT);
3507 JavaCallArguments args;
3508 args.push_int(DisplayVMOutputToStderr);
3509 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3510 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3511 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3512 if (result.get_jint() != JNI_OK) {
3513 vm_exit_during_initialization(); // no message or exception
3514 }
3515
3516 universe_post_module_init();
3517 }
3518
3519 // Phase 3. final setup - set security manager, system class loader and TCCL
3520 //
3521 // This will instantiate and set the security manager, set the system class
3522 // loader as well as the thread context class loader. The security manager
3523 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3524 // other modules or the application's classpath.
3525 static void call_initPhase3(TRAPS) {
3526 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3527 JavaValue result(T_VOID);
3528 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3529 vmSymbols::void_method_signature(), CHECK);
3530 }
3531
3532 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3533 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3534
3535 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3536 create_vm_init_libraries();
3537 }
3538
3539 initialize_class(vmSymbols::java_lang_String(), CHECK);
3540
3541 // Inject CompactStrings value after the static initializers for String ran.
3542 java_lang_String::set_compact_strings(CompactStrings);
3543
3544 // Initialize java_lang.System (needed before creating the thread)
3545 initialize_class(vmSymbols::java_lang_System(), CHECK);
3546 // The VM creates & returns objects of this class. Make sure it's initialized.
3547 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3548 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3549 Handle thread_group = create_initial_thread_group(CHECK);
3550 Universe::set_main_thread_group(thread_group());
3551 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3552 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3553 main_thread->set_threadObj(thread_object);
3554 // Set thread status to running since main thread has
3555 // been started and running.
3556 java_lang_Thread::set_thread_status(thread_object,
3557 java_lang_Thread::RUNNABLE);
3558
3559 // The VM creates objects of this class.
3560 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3561
3562 // The VM preresolves methods to these classes. Make sure that they get initialized
3563 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3564 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3565
3566 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3567 call_initPhase1(CHECK);
3568
3569 // get the Java runtime name after java.lang.System is initialized
3570 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3571 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3572
3573 // an instance of OutOfMemory exception has been allocated earlier
3574 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3575 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3576 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3577 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3578 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3579 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3580 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3581 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3582 }
3583
3584 void Threads::initialize_jsr292_core_classes(TRAPS) {
3585 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3586
3587 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3588 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3589 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3590 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3591 }
3592
3593 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3594 extern void JDK_Version_init();
3595
3596 // Preinitialize version info.
3597 VM_Version::early_initialize();
3598
3599 // Check version
3600 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3601
3602 // Initialize library-based TLS
3603 ThreadLocalStorage::init();
3604
3605 // Initialize the output stream module
3606 ostream_init();
3607
3608 // Process java launcher properties.
3609 Arguments::process_sun_java_launcher_properties(args);
3610
3611 // Initialize the os module
3612 os::init();
3613
3614 // Record VM creation timing statistics
3615 TraceVmCreationTime create_vm_timer;
3616 create_vm_timer.start();
3617
3618 // Initialize system properties.
3619 Arguments::init_system_properties();
3620
3621 // So that JDK version can be used as a discriminator when parsing arguments
3622 JDK_Version_init();
3623
3624 // Update/Initialize System properties after JDK version number is known
3625 Arguments::init_version_specific_system_properties();
3626
3627 // Make sure to initialize log configuration *before* parsing arguments
3628 LogConfiguration::initialize(create_vm_timer.begin_time());
3629
3630 // Parse arguments
3631 // Note: this internally calls os::init_container_support()
3632 jint parse_result = Arguments::parse(args);
3633 if (parse_result != JNI_OK) return parse_result;
3634
3635 os::init_before_ergo();
3636
3637 jint ergo_result = Arguments::apply_ergo();
3638 if (ergo_result != JNI_OK) return ergo_result;
3639
3640 // Final check of all ranges after ergonomics which may change values.
3641 if (!CommandLineFlagRangeList::check_ranges()) {
3642 return JNI_EINVAL;
3643 }
3644
3645 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3646 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3647 if (!constraint_result) {
3648 return JNI_EINVAL;
3649 }
3650
3651 CommandLineFlagWriteableList::mark_startup();
3652
3653 if (PauseAtStartup) {
3654 os::pause();
3655 }
3656
3657 HOTSPOT_VM_INIT_BEGIN();
3658
3659 // Timing (must come after argument parsing)
3660 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3661
3662 // Initialize the os module after parsing the args
3663 jint os_init_2_result = os::init_2();
3664 if (os_init_2_result != JNI_OK) return os_init_2_result;
3665
3666 SafepointMechanism::initialize();
3667
3668 jint adjust_after_os_result = Arguments::adjust_after_os();
3669 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3670
3671 // Initialize output stream logging
3672 ostream_init_log();
3673
3674 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3675 // Must be before create_vm_init_agents()
3676 if (Arguments::init_libraries_at_startup()) {
3677 convert_vm_init_libraries_to_agents();
3678 }
3679
3680 // Launch -agentlib/-agentpath and converted -Xrun agents
3681 if (Arguments::init_agents_at_startup()) {
3682 create_vm_init_agents();
3683 }
3684
3685 // Initialize Threads state
3686 _thread_list = NULL;
3687 _number_of_threads = 0;
3688 _number_of_non_daemon_threads = 0;
3689
3690 // Initialize global data structures and create system classes in heap
3691 vm_init_globals();
3692
3693 #if INCLUDE_JVMCI
3694 if (JVMCICounterSize > 0) {
3695 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3696 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3697 } else {
3698 JavaThread::_jvmci_old_thread_counters = NULL;
3699 }
3700 #endif // INCLUDE_JVMCI
3701
3702 // Attach the main thread to this os thread
3703 JavaThread* main_thread = new JavaThread();
3704 main_thread->set_thread_state(_thread_in_vm);
3705 main_thread->initialize_thread_current();
3706 // must do this before set_active_handles
3707 main_thread->record_stack_base_and_size();
3708 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3709
3710 if (!main_thread->set_as_starting_thread()) {
3711 vm_shutdown_during_initialization(
3712 "Failed necessary internal allocation. Out of swap space");
3713 main_thread->smr_delete();
3714 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3715 return JNI_ENOMEM;
3716 }
3717
3718 // Enable guard page *after* os::create_main_thread(), otherwise it would
3719 // crash Linux VM, see notes in os_linux.cpp.
3720 main_thread->create_stack_guard_pages();
3721
3722 // Initialize Java-Level synchronization subsystem
3723 ObjectMonitor::Initialize();
3724
3725 // Initialize global modules
3726 jint status = init_globals();
3727 if (status != JNI_OK) {
3728 main_thread->smr_delete();
3729 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3730 return status;
3731 }
3732
3733 if (TRACE_INITIALIZE() != JNI_OK) {
3734 vm_exit_during_initialization("Failed to initialize tracing backend");
3735 }
3736
3737 // Should be done after the heap is fully created
3738 main_thread->cache_global_variables();
3739
3740 HandleMark hm;
3741
3742 { MutexLocker mu(Threads_lock);
3743 Threads::add(main_thread);
3744 }
3745
3746 // Any JVMTI raw monitors entered in onload will transition into
3747 // real raw monitor. VM is setup enough here for raw monitor enter.
3748 JvmtiExport::transition_pending_onload_raw_monitors();
3749
3750 // Create the VMThread
3751 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3752
3753 VMThread::create();
3754 Thread* vmthread = VMThread::vm_thread();
3755
3756 if (!os::create_thread(vmthread, os::vm_thread)) {
3757 vm_exit_during_initialization("Cannot create VM thread. "
3758 "Out of system resources.");
3759 }
3760
3761 // Wait for the VM thread to become ready, and VMThread::run to initialize
3762 // Monitors can have spurious returns, must always check another state flag
3763 {
3764 MutexLocker ml(Notify_lock);
3765 os::start_thread(vmthread);
3766 while (vmthread->active_handles() == NULL) {
3767 Notify_lock->wait();
3768 }
3769 }
3770 }
3771
3772 assert(Universe::is_fully_initialized(), "not initialized");
3773 if (VerifyDuringStartup) {
3774 // Make sure we're starting with a clean slate.
3775 VM_Verify verify_op;
3776 VMThread::execute(&verify_op);
3777 }
3778
3779 Thread* THREAD = Thread::current();
3780
3781 // Always call even when there are not JVMTI environments yet, since environments
3782 // may be attached late and JVMTI must track phases of VM execution
3783 JvmtiExport::enter_early_start_phase();
3784
3785 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3786 JvmtiExport::post_early_vm_start();
3787
3788 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3789
3790 // We need this for ClassDataSharing - the initial vm.info property is set
3791 // with the default value of CDS "sharing" which may be reset through
3792 // command line options.
3793 reset_vm_info_property(CHECK_JNI_ERR);
3794
3795 quicken_jni_functions();
3796
3797 // No more stub generation allowed after that point.
3798 StubCodeDesc::freeze();
3799
3800 // Set flag that basic initialization has completed. Used by exceptions and various
3801 // debug stuff, that does not work until all basic classes have been initialized.
3802 set_init_completed();
3803
3804 LogConfiguration::post_initialize();
3805 Metaspace::post_initialize();
3806
3807 HOTSPOT_VM_INIT_END();
3808
3809 // record VM initialization completion time
3810 #if INCLUDE_MANAGEMENT
3811 Management::record_vm_init_completed();
3812 #endif // INCLUDE_MANAGEMENT
3813
3814 // Signal Dispatcher needs to be started before VMInit event is posted
3815 os::signal_init(CHECK_JNI_ERR);
3816
3817 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3818 if (!DisableAttachMechanism) {
3819 AttachListener::vm_start();
3820 if (StartAttachListener || AttachListener::init_at_startup()) {
3821 AttachListener::init();
3822 }
3823 }
3824
3825 // Launch -Xrun agents
3826 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3827 // back-end can launch with -Xdebug -Xrunjdwp.
3828 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3829 create_vm_init_libraries();
3830 }
3831
3832 if (CleanChunkPoolAsync) {
3833 Chunk::start_chunk_pool_cleaner_task();
3834 }
3835
3836 // initialize compiler(s)
3837 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3838 CompileBroker::compilation_init(CHECK_JNI_ERR);
3839 #endif
3840
3841 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3842 // It is done after compilers are initialized, because otherwise compilations of
3843 // signature polymorphic MH intrinsics can be missed
3844 // (see SystemDictionary::find_method_handle_intrinsic).
3845 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3846
3847 // This will initialize the module system. Only java.base classes can be
3848 // loaded until phase 2 completes
3849 call_initPhase2(CHECK_JNI_ERR);
3850
3851 // Always call even when there are not JVMTI environments yet, since environments
3852 // may be attached late and JVMTI must track phases of VM execution
3853 JvmtiExport::enter_start_phase();
3854
3855 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3856 JvmtiExport::post_vm_start();
3857
3858 // Final system initialization including security manager and system class loader
3859 call_initPhase3(CHECK_JNI_ERR);
3860
3861 // cache the system and platform class loaders
3862 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3863
3864 #if INCLUDE_JVMCI
3865 if (EnableJVMCI) {
3866 // Initialize JVMCI eagerly when it is explicitly requested.
3867 // Or when JVMCIPrintProperties is enabled.
3868 // The JVMCI Java initialization code will read this flag and
3869 // do the printing if it's set.
3870 bool init = EagerJVMCI || JVMCIPrintProperties;
3871
3872 if (!init) {
3873 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3874 // compilations via JVMCI will not actually block until JVMCI is initialized.
3875 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3876 }
3877
3878 if (init) {
3879 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3880 }
3881 }
3882 #endif
3883
3884 // Always call even when there are not JVMTI environments yet, since environments
3885 // may be attached late and JVMTI must track phases of VM execution
3886 JvmtiExport::enter_live_phase();
3887
3888 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3889 JvmtiExport::post_vm_initialized();
3890
3891 if (TRACE_START() != JNI_OK) {
3892 vm_exit_during_initialization("Failed to start tracing backend.");
3893 }
3894
3895 #if INCLUDE_MANAGEMENT
3896 Management::initialize(THREAD);
3897
3898 if (HAS_PENDING_EXCEPTION) {
3899 // management agent fails to start possibly due to
3900 // configuration problem and is responsible for printing
3901 // stack trace if appropriate. Simply exit VM.
3902 vm_exit(1);
3903 }
3904 #endif // INCLUDE_MANAGEMENT
3905
3906 if (MemProfiling) MemProfiler::engage();
3907 StatSampler::engage();
3908 if (CheckJNICalls) JniPeriodicChecker::engage();
3909
3910 BiasedLocking::init();
3911
3912 #if INCLUDE_RTM_OPT
3913 RTMLockingCounters::init();
3914 #endif
3915
3916 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3917 call_postVMInitHook(THREAD);
3918 // The Java side of PostVMInitHook.run must deal with all
3919 // exceptions and provide means of diagnosis.
3920 if (HAS_PENDING_EXCEPTION) {
3921 CLEAR_PENDING_EXCEPTION;
3922 }
3923 }
3924
3925 {
3926 MutexLocker ml(PeriodicTask_lock);
3927 // Make sure the WatcherThread can be started by WatcherThread::start()
3928 // or by dynamic enrollment.
3929 WatcherThread::make_startable();
3930 // Start up the WatcherThread if there are any periodic tasks
3931 // NOTE: All PeriodicTasks should be registered by now. If they
3932 // aren't, late joiners might appear to start slowly (we might
3933 // take a while to process their first tick).
3934 if (PeriodicTask::num_tasks() > 0) {
3935 WatcherThread::start();
3936 }
3937 }
3938
3939 create_vm_timer.end();
3940 #ifdef ASSERT
3941 _vm_complete = true;
3942 #endif
3943
3944 if (DumpSharedSpaces) {
3945 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3946 ShouldNotReachHere();
3947 }
3948
3949 return JNI_OK;
3950 }
3951
3952 // type for the Agent_OnLoad and JVM_OnLoad entry points
3953 extern "C" {
3954 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3955 }
3956 // Find a command line agent library and return its entry point for
3957 // -agentlib: -agentpath: -Xrun
3958 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3959 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3960 const char *on_load_symbols[],
3961 size_t num_symbol_entries) {
3962 OnLoadEntry_t on_load_entry = NULL;
3963 void *library = NULL;
3964
3965 if (!agent->valid()) {
3966 char buffer[JVM_MAXPATHLEN];
3967 char ebuf[1024] = "";
3968 const char *name = agent->name();
3969 const char *msg = "Could not find agent library ";
3970
3971 // First check to see if agent is statically linked into executable
3972 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3973 library = agent->os_lib();
3974 } else if (agent->is_absolute_path()) {
3975 library = os::dll_load(name, ebuf, sizeof ebuf);
3976 if (library == NULL) {
3977 const char *sub_msg = " in absolute path, with error: ";
3978 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3979 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3980 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3981 // If we can't find the agent, exit.
3982 vm_exit_during_initialization(buf, NULL);
3983 FREE_C_HEAP_ARRAY(char, buf);
3984 }
3985 } else {
3986 // Try to load the agent from the standard dll directory
3987 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3988 name)) {
3989 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3990 }
3991 if (library == NULL) { // Try the library path directory.
3992 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3993 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3994 }
3995 if (library == NULL) {
3996 const char *sub_msg = " on the library path, with error: ";
3997 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
3998
3999 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4000 strlen(ebuf) + strlen(sub_msg2) + 1;
4001 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4002 if (!agent->is_instrument_lib()) {
4003 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4004 } else {
4005 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4006 }
4007 // If we can't find the agent, exit.
4008 vm_exit_during_initialization(buf, NULL);
4009 FREE_C_HEAP_ARRAY(char, buf);
4010 }
4011 }
4012 }
4013 agent->set_os_lib(library);
4014 agent->set_valid();
4015 }
4016
4017 // Find the OnLoad function.
4018 on_load_entry =
4019 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4020 false,
4021 on_load_symbols,
4022 num_symbol_entries));
4023 return on_load_entry;
4024 }
4025
4026 // Find the JVM_OnLoad entry point
4027 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4028 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4029 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4030 }
4031
4032 // Find the Agent_OnLoad entry point
4033 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4034 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4035 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4036 }
4037
4038 // For backwards compatibility with -Xrun
4039 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4040 // treated like -agentpath:
4041 // Must be called before agent libraries are created
4042 void Threads::convert_vm_init_libraries_to_agents() {
4043 AgentLibrary* agent;
4044 AgentLibrary* next;
4045
4046 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4047 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4048 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4049
4050 // If there is an JVM_OnLoad function it will get called later,
4051 // otherwise see if there is an Agent_OnLoad
4052 if (on_load_entry == NULL) {
4053 on_load_entry = lookup_agent_on_load(agent);
4054 if (on_load_entry != NULL) {
4055 // switch it to the agent list -- so that Agent_OnLoad will be called,
4056 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4057 Arguments::convert_library_to_agent(agent);
4058 } else {
4059 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4060 }
4061 }
4062 }
4063 }
4064
4065 // Create agents for -agentlib: -agentpath: and converted -Xrun
4066 // Invokes Agent_OnLoad
4067 // Called very early -- before JavaThreads exist
4068 void Threads::create_vm_init_agents() {
4069 extern struct JavaVM_ main_vm;
4070 AgentLibrary* agent;
4071
4072 JvmtiExport::enter_onload_phase();
4073
4074 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4075 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4076
4077 if (on_load_entry != NULL) {
4078 // Invoke the Agent_OnLoad function
4079 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4080 if (err != JNI_OK) {
4081 vm_exit_during_initialization("agent library failed to init", agent->name());
4082 }
4083 } else {
4084 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4085 }
4086 }
4087 JvmtiExport::enter_primordial_phase();
4088 }
4089
4090 extern "C" {
4091 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4092 }
4093
4094 void Threads::shutdown_vm_agents() {
4095 // Send any Agent_OnUnload notifications
4096 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4097 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4098 extern struct JavaVM_ main_vm;
4099 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4100
4101 // Find the Agent_OnUnload function.
4102 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4103 os::find_agent_function(agent,
4104 false,
4105 on_unload_symbols,
4106 num_symbol_entries));
4107
4108 // Invoke the Agent_OnUnload function
4109 if (unload_entry != NULL) {
4110 JavaThread* thread = JavaThread::current();
4111 ThreadToNativeFromVM ttn(thread);
4112 HandleMark hm(thread);
4113 (*unload_entry)(&main_vm);
4114 }
4115 }
4116 }
4117
4118 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4119 // Invokes JVM_OnLoad
4120 void Threads::create_vm_init_libraries() {
4121 extern struct JavaVM_ main_vm;
4122 AgentLibrary* agent;
4123
4124 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4125 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4126
4127 if (on_load_entry != NULL) {
4128 // Invoke the JVM_OnLoad function
4129 JavaThread* thread = JavaThread::current();
4130 ThreadToNativeFromVM ttn(thread);
4131 HandleMark hm(thread);
4132 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4133 if (err != JNI_OK) {
4134 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4135 }
4136 } else {
4137 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4138 }
4139 }
4140 }
4141
4142
4143 // Last thread running calls java.lang.Shutdown.shutdown()
4144 void JavaThread::invoke_shutdown_hooks() {
4145 HandleMark hm(this);
4146
4147 // We could get here with a pending exception, if so clear it now.
4148 if (this->has_pending_exception()) {
4149 this->clear_pending_exception();
4150 }
4151
4152 EXCEPTION_MARK;
4153 Klass* shutdown_klass =
4154 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4155 THREAD);
4156 if (shutdown_klass != NULL) {
4157 // SystemDictionary::resolve_or_null will return null if there was
4158 // an exception. If we cannot load the Shutdown class, just don't
4159 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4160 // won't be run. Note that if a shutdown hook was registered,
4161 // the Shutdown class would have already been loaded
4162 // (Runtime.addShutdownHook will load it).
4163 JavaValue result(T_VOID);
4164 JavaCalls::call_static(&result,
4165 shutdown_klass,
4166 vmSymbols::shutdown_method_name(),
4167 vmSymbols::void_method_signature(),
4168 THREAD);
4169 }
4170 CLEAR_PENDING_EXCEPTION;
4171 }
4172
4173 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4174 // the program falls off the end of main(). Another VM exit path is through
4175 // vm_exit() when the program calls System.exit() to return a value or when
4176 // there is a serious error in VM. The two shutdown paths are not exactly
4177 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4178 // and VM_Exit op at VM level.
4179 //
4180 // Shutdown sequence:
4181 // + Shutdown native memory tracking if it is on
4182 // + Wait until we are the last non-daemon thread to execute
4183 // <-- every thing is still working at this moment -->
4184 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4185 // shutdown hooks
4186 // + Call before_exit(), prepare for VM exit
4187 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4188 // currently the only user of this mechanism is File.deleteOnExit())
4189 // > stop StatSampler, watcher thread, CMS threads,
4190 // post thread end and vm death events to JVMTI,
4191 // stop signal thread
4192 // + Call JavaThread::exit(), it will:
4193 // > release JNI handle blocks, remove stack guard pages
4194 // > remove this thread from Threads list
4195 // <-- no more Java code from this thread after this point -->
4196 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4197 // the compiler threads at safepoint
4198 // <-- do not use anything that could get blocked by Safepoint -->
4199 // + Disable tracing at JNI/JVM barriers
4200 // + Set _vm_exited flag for threads that are still running native code
4201 // + Delete this thread
4202 // + Call exit_globals()
4203 // > deletes tty
4204 // > deletes PerfMemory resources
4205 // + Return to caller
4206
4207 bool Threads::destroy_vm() {
4208 JavaThread* thread = JavaThread::current();
4209
4210 #ifdef ASSERT
4211 _vm_complete = false;
4212 #endif
4213 // Wait until we are the last non-daemon thread to execute
4214 { MutexLocker nu(Threads_lock);
4215 while (Threads::number_of_non_daemon_threads() > 1)
4216 // This wait should make safepoint checks, wait without a timeout,
4217 // and wait as a suspend-equivalent condition.
4218 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4219 Mutex::_as_suspend_equivalent_flag);
4220 }
4221
4222 EventShutdown e;
4223 if (e.should_commit()) {
4224 e.set_reason("No remaining non-daemon Java threads");
4225 e.commit();
4226 }
4227
4228 // Hang forever on exit if we are reporting an error.
4229 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4230 os::infinite_sleep();
4231 }
4232 os::wait_for_keypress_at_exit();
4233
4234 // run Java level shutdown hooks
4235 thread->invoke_shutdown_hooks();
4236
4237 before_exit(thread);
4238
4239 thread->exit(true);
4240
4241 // Stop VM thread.
4242 {
4243 // 4945125 The vm thread comes to a safepoint during exit.
4244 // GC vm_operations can get caught at the safepoint, and the
4245 // heap is unparseable if they are caught. Grab the Heap_lock
4246 // to prevent this. The GC vm_operations will not be able to
4247 // queue until after the vm thread is dead. After this point,
4248 // we'll never emerge out of the safepoint before the VM exits.
4249
4250 MutexLocker ml(Heap_lock);
4251
4252 VMThread::wait_for_vm_thread_exit();
4253 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4254 VMThread::destroy();
4255 }
4256
4257 // clean up ideal graph printers
4258 #if defined(COMPILER2) && !defined(PRODUCT)
4259 IdealGraphPrinter::clean_up();
4260 #endif
4261
4262 // Now, all Java threads are gone except daemon threads. Daemon threads
4263 // running Java code or in VM are stopped by the Safepoint. However,
4264 // daemon threads executing native code are still running. But they
4265 // will be stopped at native=>Java/VM barriers. Note that we can't
4266 // simply kill or suspend them, as it is inherently deadlock-prone.
4267
4268 VM_Exit::set_vm_exited();
4269
4270 notify_vm_shutdown();
4271
4272 // We are after VM_Exit::set_vm_exited() so we can't call
4273 // thread->smr_delete() or we will block on the Threads_lock.
4274 // Deleting the shutdown thread here is safe because another
4275 // JavaThread cannot have an active ThreadsListHandle for
4276 // this JavaThread.
4277 delete thread;
4278
4279 #if INCLUDE_JVMCI
4280 if (JVMCICounterSize > 0) {
4281 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4282 }
4283 #endif
4284
4285 // exit_globals() will delete tty
4286 exit_globals();
4287
4288 LogConfiguration::finalize();
4289
4290 return true;
4291 }
4292
4293
4294 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4295 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4296 return is_supported_jni_version(version);
4297 }
4298
4299
4300 jboolean Threads::is_supported_jni_version(jint version) {
4301 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4302 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4303 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4304 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4305 if (version == JNI_VERSION_9) return JNI_TRUE;
4306 if (version == JNI_VERSION_10) return JNI_TRUE;
4307 return JNI_FALSE;
4308 }
4309
4310
4311 void Threads::add(JavaThread* p, bool force_daemon) {
4312 // The threads lock must be owned at this point
4313 assert_locked_or_safepoint(Threads_lock);
4314
4315 BarrierSet::barrier_set()->on_thread_attach(p);
4316
4317 p->set_next(_thread_list);
4318 _thread_list = p;
4319
4320 // Once a JavaThread is added to the Threads list, smr_delete() has
4321 // to be used to delete it. Otherwise we can just delete it directly.
4322 p->set_on_thread_list();
4323
4324 _number_of_threads++;
4325 oop threadObj = p->threadObj();
4326 bool daemon = true;
4327 // Bootstrapping problem: threadObj can be null for initial
4328 // JavaThread (or for threads attached via JNI)
4329 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4330 _number_of_non_daemon_threads++;
4331 daemon = false;
4332 }
4333
4334 ThreadService::add_thread(p, daemon);
4335
4336 // Maintain fast thread list
4337 ThreadsSMRSupport::add_thread(p);
4338
4339 // Possible GC point.
4340 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4341 }
4342
4343 void Threads::remove(JavaThread* p) {
4344
4345 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4346 ObjectSynchronizer::omFlush(p);
4347
4348 // Extra scope needed for Thread_lock, so we can check
4349 // that we do not remove thread without safepoint code notice
4350 { MutexLocker ml(Threads_lock);
4351
4352 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4353
4354 // Maintain fast thread list
4355 ThreadsSMRSupport::remove_thread(p);
4356
4357 JavaThread* current = _thread_list;
4358 JavaThread* prev = NULL;
4359
4360 while (current != p) {
4361 prev = current;
4362 current = current->next();
4363 }
4364
4365 if (prev) {
4366 prev->set_next(current->next());
4367 } else {
4368 _thread_list = p->next();
4369 }
4370
4371 _number_of_threads--;
4372 oop threadObj = p->threadObj();
4373 bool daemon = true;
4374 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4375 _number_of_non_daemon_threads--;
4376 daemon = false;
4377
4378 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4379 // on destroy_vm will wake up.
4380 if (number_of_non_daemon_threads() == 1) {
4381 Threads_lock->notify_all();
4382 }
4383 }
4384 ThreadService::remove_thread(p, daemon);
4385
4386 // Make sure that safepoint code disregard this thread. This is needed since
4387 // the thread might mess around with locks after this point. This can cause it
4388 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4389 // of this thread since it is removed from the queue.
4390 p->set_terminated_value();
4391 } // unlock Threads_lock
4392
4393 // Since Events::log uses a lock, we grab it outside the Threads_lock
4394 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4395 }
4396
4397 // Operations on the Threads list for GC. These are not explicitly locked,
4398 // but the garbage collector must provide a safe context for them to run.
4399 // In particular, these things should never be called when the Threads_lock
4400 // is held by some other thread. (Note: the Safepoint abstraction also
4401 // uses the Threads_lock to guarantee this property. It also makes sure that
4402 // all threads gets blocked when exiting or starting).
4403
4404 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4405 ALL_JAVA_THREADS(p) {
4406 p->oops_do(f, cf);
4407 }
4408 VMThread::vm_thread()->oops_do(f, cf);
4409 }
4410
4411 void Threads::change_thread_claim_parity() {
4412 // Set the new claim parity.
4413 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4414 "Not in range.");
4415 _thread_claim_parity++;
4416 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4417 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4418 "Not in range.");
4419 }
4420
4421 #ifdef ASSERT
4422 void Threads::assert_all_threads_claimed() {
4423 ALL_JAVA_THREADS(p) {
4424 const int thread_parity = p->oops_do_parity();
4425 assert((thread_parity == _thread_claim_parity),
4426 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4427 }
4428 VMThread* vmt = VMThread::vm_thread();
4429 const int thread_parity = vmt->oops_do_parity();
4430 assert((thread_parity == _thread_claim_parity),
4431 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4432 }
4433 #endif // ASSERT
4434
4435 class ParallelOopsDoThreadClosure : public ThreadClosure {
4436 private:
4437 OopClosure* _f;
4438 CodeBlobClosure* _cf;
4439 public:
4440 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4441 void do_thread(Thread* t) {
4442 t->oops_do(_f, _cf);
4443 }
4444 };
4445
4446 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4447 ParallelOopsDoThreadClosure tc(f, cf);
4448 possibly_parallel_threads_do(is_par, &tc);
4449 }
4450
4451 #if INCLUDE_ALL_GCS
4452 // Used by ParallelScavenge
4453 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4454 ALL_JAVA_THREADS(p) {
4455 q->enqueue(new ThreadRootsTask(p));
4456 }
4457 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4458 }
4459
4460 // Used by Parallel Old
4461 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4462 ALL_JAVA_THREADS(p) {
4463 q->enqueue(new ThreadRootsMarkingTask(p));
4464 }
4465 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4466 }
4467 #endif // INCLUDE_ALL_GCS
4468
4469 void Threads::nmethods_do(CodeBlobClosure* cf) {
4470 ALL_JAVA_THREADS(p) {
4471 // This is used by the code cache sweeper to mark nmethods that are active
4472 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4473 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4474 if(!p->is_Code_cache_sweeper_thread()) {
4475 p->nmethods_do(cf);
4476 }
4477 }
4478 }
4479
4480 void Threads::metadata_do(void f(Metadata*)) {
4481 ALL_JAVA_THREADS(p) {
4482 p->metadata_do(f);
4483 }
4484 }
4485
4486 class ThreadHandlesClosure : public ThreadClosure {
4487 void (*_f)(Metadata*);
4488 public:
4489 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4490 virtual void do_thread(Thread* thread) {
4491 thread->metadata_handles_do(_f);
4492 }
4493 };
4494
4495 void Threads::metadata_handles_do(void f(Metadata*)) {
4496 // Only walk the Handles in Thread.
4497 ThreadHandlesClosure handles_closure(f);
4498 threads_do(&handles_closure);
4499 }
4500
4501 void Threads::deoptimized_wrt_marked_nmethods() {
4502 ALL_JAVA_THREADS(p) {
4503 p->deoptimized_wrt_marked_nmethods();
4504 }
4505 }
4506
4507
4508 // Get count Java threads that are waiting to enter the specified monitor.
4509 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4510 int count,
4511 address monitor) {
4512 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4513
4514 int i = 0;
4515 DO_JAVA_THREADS(t_list, p) {
4516 if (!p->can_call_java()) continue;
4517
4518 address pending = (address)p->current_pending_monitor();
4519 if (pending == monitor) { // found a match
4520 if (i < count) result->append(p); // save the first count matches
4521 i++;
4522 }
4523 }
4524
4525 return result;
4526 }
4527
4528
4529 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4530 address owner) {
4531 // NULL owner means not locked so we can skip the search
4532 if (owner == NULL) return NULL;
4533
4534 DO_JAVA_THREADS(t_list, p) {
4535 // first, see if owner is the address of a Java thread
4536 if (owner == (address)p) return p;
4537 }
4538
4539 // Cannot assert on lack of success here since this function may be
4540 // used by code that is trying to report useful problem information
4541 // like deadlock detection.
4542 if (UseHeavyMonitors) return NULL;
4543
4544 // If we didn't find a matching Java thread and we didn't force use of
4545 // heavyweight monitors, then the owner is the stack address of the
4546 // Lock Word in the owning Java thread's stack.
4547 //
4548 JavaThread* the_owner = NULL;
4549 DO_JAVA_THREADS(t_list, q) {
4550 if (q->is_lock_owned(owner)) {
4551 the_owner = q;
4552 break;
4553 }
4554 }
4555
4556 // cannot assert on lack of success here; see above comment
4557 return the_owner;
4558 }
4559
4560 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4561 void Threads::print_on(outputStream* st, bool print_stacks,
4562 bool internal_format, bool print_concurrent_locks) {
4563 char buf[32];
4564 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4565
4566 st->print_cr("Full thread dump %s (%s %s):",
4567 Abstract_VM_Version::vm_name(),
4568 Abstract_VM_Version::vm_release(),
4569 Abstract_VM_Version::vm_info_string());
4570 st->cr();
4571
4572 #if INCLUDE_SERVICES
4573 // Dump concurrent locks
4574 ConcurrentLocksDump concurrent_locks;
4575 if (print_concurrent_locks) {
4576 concurrent_locks.dump_at_safepoint();
4577 }
4578 #endif // INCLUDE_SERVICES
4579
4580 ThreadsSMRSupport::print_info_on(st);
4581 st->cr();
4582
4583 ALL_JAVA_THREADS(p) {
4584 ResourceMark rm;
4585 p->print_on(st);
4586 if (print_stacks) {
4587 if (internal_format) {
4588 p->trace_stack();
4589 } else {
4590 p->print_stack_on(st);
4591 }
4592 }
4593 st->cr();
4594 #if INCLUDE_SERVICES
4595 if (print_concurrent_locks) {
4596 concurrent_locks.print_locks_on(p, st);
4597 }
4598 #endif // INCLUDE_SERVICES
4599 }
4600
4601 VMThread::vm_thread()->print_on(st);
4602 st->cr();
4603 Universe::heap()->print_gc_threads_on(st);
4604 WatcherThread* wt = WatcherThread::watcher_thread();
4605 if (wt != NULL) {
4606 wt->print_on(st);
4607 st->cr();
4608 }
4609
4610 st->flush();
4611 }
4612
4613 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4614 int buflen, bool* found_current) {
4615 if (this_thread != NULL) {
4616 bool is_current = (current == this_thread);
4617 *found_current = *found_current || is_current;
4618 st->print("%s", is_current ? "=>" : " ");
4619
4620 st->print(PTR_FORMAT, p2i(this_thread));
4621 st->print(" ");
4622 this_thread->print_on_error(st, buf, buflen);
4623 st->cr();
4624 }
4625 }
4626
4627 class PrintOnErrorClosure : public ThreadClosure {
4628 outputStream* _st;
4629 Thread* _current;
4630 char* _buf;
4631 int _buflen;
4632 bool* _found_current;
4633 public:
4634 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4635 int buflen, bool* found_current) :
4636 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4637
4638 virtual void do_thread(Thread* thread) {
4639 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4640 }
4641 };
4642
4643 // Threads::print_on_error() is called by fatal error handler. It's possible
4644 // that VM is not at safepoint and/or current thread is inside signal handler.
4645 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4646 // memory (even in resource area), it might deadlock the error handler.
4647 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4648 int buflen) {
4649 ThreadsSMRSupport::print_info_on(st);
4650 st->cr();
4651
4652 bool found_current = false;
4653 st->print_cr("Java Threads: ( => current thread )");
4654 ALL_JAVA_THREADS(thread) {
4655 print_on_error(thread, st, current, buf, buflen, &found_current);
4656 }
4657 st->cr();
4658
4659 st->print_cr("Other Threads:");
4660 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4661 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4662
4663 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4664 Universe::heap()->gc_threads_do(&print_closure);
4665
4666 if (!found_current) {
4667 st->cr();
4668 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4669 current->print_on_error(st, buf, buflen);
4670 st->cr();
4671 }
4672 st->cr();
4673
4674 st->print_cr("Threads with active compile tasks:");
4675 print_threads_compiling(st, buf, buflen);
4676 }
4677
4678 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4679 ALL_JAVA_THREADS(thread) {
4680 if (thread->is_Compiler_thread()) {
4681 CompilerThread* ct = (CompilerThread*) thread;
4682
4683 // Keep task in local variable for NULL check.
4684 // ct->_task might be set to NULL by concurring compiler thread
4685 // because it completed the compilation. The task is never freed,
4686 // though, just returned to a free list.
4687 CompileTask* task = ct->task();
4688 if (task != NULL) {
4689 thread->print_name_on_error(st, buf, buflen);
4690 task->print(st, NULL, true, true);
4691 }
4692 }
4693 }
4694 }
4695
4696
4697 // Internal SpinLock and Mutex
4698 // Based on ParkEvent
4699
4700 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4701 //
4702 // We employ SpinLocks _only for low-contention, fixed-length
4703 // short-duration critical sections where we're concerned
4704 // about native mutex_t or HotSpot Mutex:: latency.
4705 // The mux construct provides a spin-then-block mutual exclusion
4706 // mechanism.
4707 //
4708 // Testing has shown that contention on the ListLock guarding gFreeList
4709 // is common. If we implement ListLock as a simple SpinLock it's common
4710 // for the JVM to devolve to yielding with little progress. This is true
4711 // despite the fact that the critical sections protected by ListLock are
4712 // extremely short.
4713 //
4714 // TODO-FIXME: ListLock should be of type SpinLock.
4715 // We should make this a 1st-class type, integrated into the lock
4716 // hierarchy as leaf-locks. Critically, the SpinLock structure
4717 // should have sufficient padding to avoid false-sharing and excessive
4718 // cache-coherency traffic.
4719
4720
4721 typedef volatile int SpinLockT;
4722
4723 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4724 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4725 return; // normal fast-path return
4726 }
4727
4728 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4729 TEVENT(SpinAcquire - ctx);
4730 int ctr = 0;
4731 int Yields = 0;
4732 for (;;) {
4733 while (*adr != 0) {
4734 ++ctr;
4735 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4736 if (Yields > 5) {
4737 os::naked_short_sleep(1);
4738 } else {
4739 os::naked_yield();
4740 ++Yields;
4741 }
4742 } else {
4743 SpinPause();
4744 }
4745 }
4746 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4747 }
4748 }
4749
4750 void Thread::SpinRelease(volatile int * adr) {
4751 assert(*adr != 0, "invariant");
4752 OrderAccess::fence(); // guarantee at least release consistency.
4753 // Roach-motel semantics.
4754 // It's safe if subsequent LDs and STs float "up" into the critical section,
4755 // but prior LDs and STs within the critical section can't be allowed
4756 // to reorder or float past the ST that releases the lock.
4757 // Loads and stores in the critical section - which appear in program
4758 // order before the store that releases the lock - must also appear
4759 // before the store that releases the lock in memory visibility order.
4760 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4761 // the ST of 0 into the lock-word which releases the lock, so fence
4762 // more than covers this on all platforms.
4763 *adr = 0;
4764 }
4765
4766 // muxAcquire and muxRelease:
4767 //
4768 // * muxAcquire and muxRelease support a single-word lock-word construct.
4769 // The LSB of the word is set IFF the lock is held.
4770 // The remainder of the word points to the head of a singly-linked list
4771 // of threads blocked on the lock.
4772 //
4773 // * The current implementation of muxAcquire-muxRelease uses its own
4774 // dedicated Thread._MuxEvent instance. If we're interested in
4775 // minimizing the peak number of extant ParkEvent instances then
4776 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4777 // as certain invariants were satisfied. Specifically, care would need
4778 // to be taken with regards to consuming unpark() "permits".
4779 // A safe rule of thumb is that a thread would never call muxAcquire()
4780 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4781 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4782 // consume an unpark() permit intended for monitorenter, for instance.
4783 // One way around this would be to widen the restricted-range semaphore
4784 // implemented in park(). Another alternative would be to provide
4785 // multiple instances of the PlatformEvent() for each thread. One
4786 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4787 //
4788 // * Usage:
4789 // -- Only as leaf locks
4790 // -- for short-term locking only as muxAcquire does not perform
4791 // thread state transitions.
4792 //
4793 // Alternatives:
4794 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4795 // but with parking or spin-then-park instead of pure spinning.
4796 // * Use Taura-Oyama-Yonenzawa locks.
4797 // * It's possible to construct a 1-0 lock if we encode the lockword as
4798 // (List,LockByte). Acquire will CAS the full lockword while Release
4799 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4800 // acquiring threads use timers (ParkTimed) to detect and recover from
4801 // the stranding window. Thread/Node structures must be aligned on 256-byte
4802 // boundaries by using placement-new.
4803 // * Augment MCS with advisory back-link fields maintained with CAS().
4804 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4805 // The validity of the backlinks must be ratified before we trust the value.
4806 // If the backlinks are invalid the exiting thread must back-track through the
4807 // the forward links, which are always trustworthy.
4808 // * Add a successor indication. The LockWord is currently encoded as
4809 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4810 // to provide the usual futile-wakeup optimization.
4811 // See RTStt for details.
4812 // * Consider schedctl.sc_nopreempt to cover the critical section.
4813 //
4814
4815
4816 const intptr_t LOCKBIT = 1;
4817
4818 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4819 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4820 if (w == 0) return;
4821 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4822 return;
4823 }
4824
4825 TEVENT(muxAcquire - Contention);
4826 ParkEvent * const Self = Thread::current()->_MuxEvent;
4827 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4828 for (;;) {
4829 int its = (os::is_MP() ? 100 : 0) + 1;
4830
4831 // Optional spin phase: spin-then-park strategy
4832 while (--its >= 0) {
4833 w = *Lock;
4834 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4835 return;
4836 }
4837 }
4838
4839 Self->reset();
4840 Self->OnList = intptr_t(Lock);
4841 // The following fence() isn't _strictly necessary as the subsequent
4842 // CAS() both serializes execution and ratifies the fetched *Lock value.
4843 OrderAccess::fence();
4844 for (;;) {
4845 w = *Lock;
4846 if ((w & LOCKBIT) == 0) {
4847 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4848 Self->OnList = 0; // hygiene - allows stronger asserts
4849 return;
4850 }
4851 continue; // Interference -- *Lock changed -- Just retry
4852 }
4853 assert(w & LOCKBIT, "invariant");
4854 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4855 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4856 }
4857
4858 while (Self->OnList != 0) {
4859 Self->park();
4860 }
4861 }
4862 }
4863
4864 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4865 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4866 if (w == 0) return;
4867 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4868 return;
4869 }
4870
4871 TEVENT(muxAcquire - Contention);
4872 ParkEvent * ReleaseAfter = NULL;
4873 if (ev == NULL) {
4874 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4875 }
4876 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4877 for (;;) {
4878 guarantee(ev->OnList == 0, "invariant");
4879 int its = (os::is_MP() ? 100 : 0) + 1;
4880
4881 // Optional spin phase: spin-then-park strategy
4882 while (--its >= 0) {
4883 w = *Lock;
4884 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4885 if (ReleaseAfter != NULL) {
4886 ParkEvent::Release(ReleaseAfter);
4887 }
4888 return;
4889 }
4890 }
4891
4892 ev->reset();
4893 ev->OnList = intptr_t(Lock);
4894 // The following fence() isn't _strictly necessary as the subsequent
4895 // CAS() both serializes execution and ratifies the fetched *Lock value.
4896 OrderAccess::fence();
4897 for (;;) {
4898 w = *Lock;
4899 if ((w & LOCKBIT) == 0) {
4900 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4901 ev->OnList = 0;
4902 // We call ::Release while holding the outer lock, thus
4903 // artificially lengthening the critical section.
4904 // Consider deferring the ::Release() until the subsequent unlock(),
4905 // after we've dropped the outer lock.
4906 if (ReleaseAfter != NULL) {
4907 ParkEvent::Release(ReleaseAfter);
4908 }
4909 return;
4910 }
4911 continue; // Interference -- *Lock changed -- Just retry
4912 }
4913 assert(w & LOCKBIT, "invariant");
4914 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4915 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4916 }
4917
4918 while (ev->OnList != 0) {
4919 ev->park();
4920 }
4921 }
4922 }
4923
4924 // Release() must extract a successor from the list and then wake that thread.
4925 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4926 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4927 // Release() would :
4928 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4929 // (B) Extract a successor from the private list "in-hand"
4930 // (C) attempt to CAS() the residual back into *Lock over null.
4931 // If there were any newly arrived threads and the CAS() would fail.
4932 // In that case Release() would detach the RATs, re-merge the list in-hand
4933 // with the RATs and repeat as needed. Alternately, Release() might
4934 // detach and extract a successor, but then pass the residual list to the wakee.
4935 // The wakee would be responsible for reattaching and remerging before it
4936 // competed for the lock.
4937 //
4938 // Both "pop" and DMR are immune from ABA corruption -- there can be
4939 // multiple concurrent pushers, but only one popper or detacher.
4940 // This implementation pops from the head of the list. This is unfair,
4941 // but tends to provide excellent throughput as hot threads remain hot.
4942 // (We wake recently run threads first).
4943 //
4944 // All paths through muxRelease() will execute a CAS.
4945 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4946 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4947 // executed within the critical section are complete and globally visible before the
4948 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4949 void Thread::muxRelease(volatile intptr_t * Lock) {
4950 for (;;) {
4951 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4952 assert(w & LOCKBIT, "invariant");
4953 if (w == LOCKBIT) return;
4954 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4955 assert(List != NULL, "invariant");
4956 assert(List->OnList == intptr_t(Lock), "invariant");
4957 ParkEvent * const nxt = List->ListNext;
4958 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4959
4960 // The following CAS() releases the lock and pops the head element.
4961 // The CAS() also ratifies the previously fetched lock-word value.
4962 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4963 continue;
4964 }
4965 List->OnList = 0;
4966 OrderAccess::fence();
4967 List->unpark();
4968 return;
4969 }
4970 }
4971
4972
4973 void Threads::verify() {
4974 ALL_JAVA_THREADS(p) {
4975 p->verify();
4976 }
4977 VMThread* thread = VMThread::vm_thread();
4978 if (thread != NULL) thread->verify();
4979 }