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/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jfr/support/jfrThreadId.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "prims/privilegedStack.hpp"
65 #include "runtime/arguments.hpp"
66 #include "runtime/atomic.hpp"
67 #include "runtime/biasedLocking.hpp"
68 #include "runtime/fieldDescriptor.inline.hpp"
69 #include "runtime/flags/jvmFlagConstraintList.hpp"
70 #include "runtime/flags/jvmFlagRangeList.hpp"
71 #include "runtime/flags/jvmFlagWriteableList.hpp"
72 #include "runtime/deoptimization.hpp"
73 #include "runtime/frame.inline.hpp"
74 #include "runtime/handshake.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/jniHandles.inline.hpp"
80 #include "runtime/jniPeriodicChecker.hpp"
81 #include "runtime/memprofiler.hpp"
82 #include "runtime/mutexLocker.hpp"
83 #include "runtime/objectMonitor.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/osThread.hpp"
86 #include "runtime/prefetch.inline.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/safepointMechanism.inline.hpp"
89 #include "runtime/safepointVerifiers.hpp"
90 #include "runtime/sharedRuntime.hpp"
91 #include "runtime/statSampler.hpp"
92 #include "runtime/stubRoutines.hpp"
93 #include "runtime/sweeper.hpp"
94 #include "runtime/task.hpp"
95 #include "runtime/thread.inline.hpp"
96 #include "runtime/threadCritical.hpp"
97 #include "runtime/threadSMR.inline.hpp"
98 #include "runtime/threadStatisticalInfo.hpp"
99 #include "runtime/timer.hpp"
100 #include "runtime/timerTrace.hpp"
101 #include "runtime/vframe.inline.hpp"
102 #include "runtime/vframeArray.hpp"
103 #include "runtime/vframe_hp.hpp"
104 #include "runtime/vmThread.hpp"
105 #include "runtime/vm_operations.hpp"
106 #include "runtime/vm_version.hpp"
107 #include "services/attachListener.hpp"
108 #include "services/management.hpp"
109 #include "services/memTracker.hpp"
110 #include "services/threadService.hpp"
111 #include "utilities/align.hpp"
112 #include "utilities/copy.hpp"
113 #include "utilities/defaultStream.hpp"
114 #include "utilities/dtrace.hpp"
115 #include "utilities/events.hpp"
116 #include "utilities/macros.hpp"
117 #include "utilities/preserveException.hpp"
118 #include "utilities/singleWriterSynchronizer.hpp"
119 #include "utilities/vmError.hpp"
120 #if INCLUDE_JVMCI
121 #include "jvmci/jvmciCompiler.hpp"
122 #include "jvmci/jvmciRuntime.hpp"
123 #include "logging/logHandle.hpp"
124 #endif
125 #ifdef COMPILER1
126 #include "c1/c1_Compiler.hpp"
127 #endif
128 #ifdef COMPILER2
129 #include "opto/c2compiler.hpp"
130 #include "opto/idealGraphPrinter.hpp"
131 #endif
132 #if INCLUDE_RTM_OPT
133 #include "runtime/rtmLocking.hpp"
134 #endif
135 #if INCLUDE_JFR
136 #include "jfr/jfr.hpp"
137 #endif
138
139 // Initialization after module runtime initialization
140 void universe_post_module_init(); // must happen after call_initPhase2
141
142 #ifdef DTRACE_ENABLED
143
144 // Only bother with this argument setup if dtrace is available
145
146 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
147 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
148
149 #define DTRACE_THREAD_PROBE(probe, javathread) \
150 { \
151 ResourceMark rm(this); \
152 int len = 0; \
153 const char* name = (javathread)->get_thread_name(); \
154 len = strlen(name); \
155 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
156 (char *) name, len, \
157 java_lang_Thread::thread_id((javathread)->threadObj()), \
158 (uintptr_t) (javathread)->osthread()->thread_id(), \
159 java_lang_Thread::is_daemon((javathread)->threadObj())); \
160 }
161
162 #else // ndef DTRACE_ENABLED
163
164 #define DTRACE_THREAD_PROBE(probe, javathread)
165
166 #endif // ndef DTRACE_ENABLED
167
168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
169 // Current thread is maintained as a thread-local variable
170 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
171 #endif
172
173 // ======= Thread ========
174 // Support for forcing alignment of thread objects for biased locking
175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
176 if (UseBiasedLocking) {
177 const int alignment = markOopDesc::biased_lock_alignment;
178 size_t aligned_size = size + (alignment - sizeof(intptr_t));
179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
180 : AllocateHeap(aligned_size, flags, CURRENT_PC,
181 AllocFailStrategy::RETURN_NULL);
182 void* aligned_addr = align_up(real_malloc_addr, alignment);
183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
185 "JavaThread alignment code overflowed allocated storage");
186 if (aligned_addr != real_malloc_addr) {
187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
188 p2i(real_malloc_addr),
189 p2i(aligned_addr));
190 }
191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
192 return aligned_addr;
193 } else {
194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
196 }
197 }
198
199 void Thread::operator delete(void* p) {
200 if (UseBiasedLocking) {
201 FreeHeap(((Thread*) p)->_real_malloc_address);
202 } else {
203 FreeHeap(p);
204 }
205 }
206
207 void JavaThread::smr_delete() {
208 if (_on_thread_list) {
209 ThreadsSMRSupport::smr_delete(this);
210 } else {
211 delete this;
212 }
213 }
214
215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
216 // JavaThread
217
218
219 Thread::Thread() {
220 // stack and get_thread
221 set_stack_base(NULL);
222 set_stack_size(0);
223 set_self_raw_id(0);
224 set_lgrp_id(-1);
225 DEBUG_ONLY(clear_suspendible_thread();)
226
227 // allocated data structures
228 set_osthread(NULL);
229 set_resource_area(new (mtThread)ResourceArea());
230 DEBUG_ONLY(_current_resource_mark = NULL;)
231 set_handle_area(new (mtThread) HandleArea(NULL));
232 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
233 set_active_handles(NULL);
234 set_free_handle_block(NULL);
235 set_last_handle_mark(NULL);
236
237 // This initial value ==> never claimed.
238 _oops_do_parity = 0;
239 _threads_hazard_ptr = NULL;
240 _threads_list_ptr = NULL;
241 _nested_threads_hazard_ptr_cnt = 0;
242 _rcu_counter = 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 _Stalled = 0;
282 _TypeTag = 0x2BAD;
283
284 // Many of the following fields are effectively final - immutable
285 // Note that nascent threads can't use the Native Monitor-Mutex
286 // construct until the _MutexEvent is initialized ...
287 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
288 // we might instead use a stack of ParkEvents that we could provision on-demand.
289 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
290 // and ::Release()
291 _ParkEvent = ParkEvent::Allocate(this);
292 _SleepEvent = ParkEvent::Allocate(this);
293 _MutexEvent = ParkEvent::Allocate(this);
294 _MuxEvent = ParkEvent::Allocate(this);
295
296 #ifdef CHECK_UNHANDLED_OOPS
297 if (CheckUnhandledOops) {
298 _unhandled_oops = new UnhandledOops(this);
299 }
300 #endif // CHECK_UNHANDLED_OOPS
301 #ifdef ASSERT
302 if (UseBiasedLocking) {
303 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
304 assert(this == _real_malloc_address ||
305 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
306 "bug in forced alignment of thread objects");
307 }
308 #endif // ASSERT
309
310 // Notify the barrier set that a thread is being created. Note that some
311 // threads are created before a barrier set is available. The call to
312 // BarrierSet::on_thread_create() for these threads is therefore deferred
313 // to BarrierSet::set_barrier_set().
314 BarrierSet* const barrier_set = BarrierSet::barrier_set();
315 if (barrier_set != NULL) {
316 barrier_set->on_thread_create(this);
317 } else {
318 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
319 }
320 }
321
322 void Thread::initialize_thread_current() {
323 #ifndef USE_LIBRARY_BASED_TLS_ONLY
324 assert(_thr_current == NULL, "Thread::current already initialized");
325 _thr_current = this;
326 #endif
327 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
328 ThreadLocalStorage::set_thread(this);
329 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
330 }
331
332 void Thread::clear_thread_current() {
333 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
334 #ifndef USE_LIBRARY_BASED_TLS_ONLY
335 _thr_current = NULL;
336 #endif
337 ThreadLocalStorage::set_thread(NULL);
338 }
339
340 void Thread::record_stack_base_and_size() {
341 set_stack_base(os::current_stack_base());
342 set_stack_size(os::current_stack_size());
343 // CR 7190089: on Solaris, primordial thread's stack is adjusted
344 // in initialize_thread(). Without the adjustment, stack size is
345 // incorrect if stack is set to unlimited (ulimit -s unlimited).
346 // So far, only Solaris has real implementation of initialize_thread().
347 //
348 // set up any platform-specific state.
349 os::initialize_thread(this);
350
351 // Set stack limits after thread is initialized.
352 if (is_Java_thread()) {
353 ((JavaThread*) this)->set_stack_overflow_limit();
354 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
355 }
356 #if INCLUDE_NMT
357 // record thread's native stack, stack grows downward
358 MemTracker::record_thread_stack(stack_end(), stack_size());
359 #endif // INCLUDE_NMT
360 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
361 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
362 os::current_thread_id(), p2i(stack_base() - stack_size()),
363 p2i(stack_base()), stack_size()/1024);
364 }
365
366
367 Thread::~Thread() {
368 JFR_ONLY(Jfr::on_thread_destruct(this);)
369
370 // Notify the barrier set that a thread is being destroyed. Note that a barrier
371 // set might not be available if we encountered errors during bootstrapping.
372 BarrierSet* const barrier_set = BarrierSet::barrier_set();
373 if (barrier_set != NULL) {
374 barrier_set->on_thread_destroy(this);
375 }
376
377
378 // stack_base can be NULL if the thread is never started or exited before
379 // record_stack_base_and_size called. Although, we would like to ensure
380 // that all started threads do call record_stack_base_and_size(), there is
381 // not proper way to enforce that.
382 #if INCLUDE_NMT
383 if (_stack_base != NULL) {
384 MemTracker::release_thread_stack(stack_end(), stack_size());
385 #ifdef ASSERT
386 set_stack_base(NULL);
387 #endif
388 }
389 #endif // INCLUDE_NMT
390
391 // deallocate data structures
392 delete resource_area();
393 // since the handle marks are using the handle area, we have to deallocated the root
394 // handle mark before deallocating the thread's handle area,
395 assert(last_handle_mark() != NULL, "check we have an element");
396 delete last_handle_mark();
397 assert(last_handle_mark() == NULL, "check we have reached the end");
398
399 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
400 // We NULL out the fields for good hygiene.
401 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
402 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
403 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
404 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
405
406 delete handle_area();
407 delete metadata_handles();
408
409 // SR_handler uses this as a termination indicator -
410 // needs to happen before os::free_thread()
411 delete _SR_lock;
412 _SR_lock = NULL;
413
414 // osthread() can be NULL, if creation of thread failed.
415 if (osthread() != NULL) os::free_thread(osthread());
416
417 // clear Thread::current if thread is deleting itself.
418 // Needed to ensure JNI correctly detects non-attached threads.
419 if (this == Thread::current()) {
420 clear_thread_current();
421 }
422
423 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
424 }
425
426 // NOTE: dummy function for assertion purpose.
427 void Thread::run() {
428 ShouldNotReachHere();
429 }
430
431 #ifdef ASSERT
432 // A JavaThread is considered "dangling" if it is not the current
433 // thread, has been added the Threads list, the system is not at a
434 // safepoint and the Thread is not "protected".
435 //
436 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
437 assert(!thread->is_Java_thread() || Thread::current() == thread ||
438 !((JavaThread *) thread)->on_thread_list() ||
439 SafepointSynchronize::is_at_safepoint() ||
440 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
441 "possibility of dangling Thread pointer");
442 }
443 #endif
444
445 ThreadPriority Thread::get_priority(const Thread* const thread) {
446 ThreadPriority priority;
447 // Can return an error!
448 (void)os::get_priority(thread, priority);
449 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
450 return priority;
451 }
452
453 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
454 debug_only(check_for_dangling_thread_pointer(thread);)
455 // Can return an error!
456 (void)os::set_priority(thread, priority);
457 }
458
459
460 void Thread::start(Thread* thread) {
461 // Start is different from resume in that its safety is guaranteed by context or
462 // being called from a Java method synchronized on the Thread object.
463 if (!DisableStartThread) {
464 if (thread->is_Java_thread()) {
465 // Initialize the thread state to RUNNABLE before starting this thread.
466 // Can not set it after the thread started because we do not know the
467 // exact thread state at that time. It could be in MONITOR_WAIT or
468 // in SLEEPING or some other state.
469 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
470 java_lang_Thread::RUNNABLE);
471 }
472 os::start_thread(thread);
473 }
474 }
475
476 // Enqueue a VM_Operation to do the job for us - sometime later
477 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
478 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
479 VMThread::execute(vm_stop);
480 }
481
482
483 // Check if an external suspend request has completed (or has been
484 // cancelled). Returns true if the thread is externally suspended and
485 // false otherwise.
486 //
487 // The bits parameter returns information about the code path through
488 // the routine. Useful for debugging:
489 //
490 // set in is_ext_suspend_completed():
491 // 0x00000001 - routine was entered
492 // 0x00000010 - routine return false at end
493 // 0x00000100 - thread exited (return false)
494 // 0x00000200 - suspend request cancelled (return false)
495 // 0x00000400 - thread suspended (return true)
496 // 0x00001000 - thread is in a suspend equivalent state (return true)
497 // 0x00002000 - thread is native and walkable (return true)
498 // 0x00004000 - thread is native_trans and walkable (needed retry)
499 //
500 // set in wait_for_ext_suspend_completion():
501 // 0x00010000 - routine was entered
502 // 0x00020000 - suspend request cancelled before loop (return false)
503 // 0x00040000 - thread suspended before loop (return true)
504 // 0x00080000 - suspend request cancelled in loop (return false)
505 // 0x00100000 - thread suspended in loop (return true)
506 // 0x00200000 - suspend not completed during retry loop (return false)
507
508 // Helper class for tracing suspend wait debug bits.
509 //
510 // 0x00000100 indicates that the target thread exited before it could
511 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
512 // 0x00080000 each indicate a cancelled suspend request so they don't
513 // count as wait failures either.
514 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
515
516 class TraceSuspendDebugBits : public StackObj {
517 private:
518 JavaThread * jt;
519 bool is_wait;
520 bool called_by_wait; // meaningful when !is_wait
521 uint32_t * bits;
522
523 public:
524 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
525 uint32_t *_bits) {
526 jt = _jt;
527 is_wait = _is_wait;
528 called_by_wait = _called_by_wait;
529 bits = _bits;
530 }
531
532 ~TraceSuspendDebugBits() {
533 if (!is_wait) {
534 #if 1
535 // By default, don't trace bits for is_ext_suspend_completed() calls.
536 // That trace is very chatty.
537 return;
538 #else
539 if (!called_by_wait) {
540 // If tracing for is_ext_suspend_completed() is enabled, then only
541 // trace calls to it from wait_for_ext_suspend_completion()
542 return;
543 }
544 #endif
545 }
546
547 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
548 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
549 MutexLocker ml(Threads_lock); // needed for get_thread_name()
550 ResourceMark rm;
551
552 tty->print_cr(
553 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
554 jt->get_thread_name(), *bits);
555
556 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
557 }
558 }
559 }
560 };
561 #undef DEBUG_FALSE_BITS
562
563
564 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
565 uint32_t *bits) {
566 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
567
568 bool did_trans_retry = false; // only do thread_in_native_trans retry once
569 bool do_trans_retry; // flag to force the retry
570
571 *bits |= 0x00000001;
572
573 do {
574 do_trans_retry = false;
575
576 if (is_exiting()) {
577 // Thread is in the process of exiting. This is always checked
578 // first to reduce the risk of dereferencing a freed JavaThread.
579 *bits |= 0x00000100;
580 return false;
581 }
582
583 if (!is_external_suspend()) {
584 // Suspend request is cancelled. This is always checked before
585 // is_ext_suspended() to reduce the risk of a rogue resume
586 // confusing the thread that made the suspend request.
587 *bits |= 0x00000200;
588 return false;
589 }
590
591 if (is_ext_suspended()) {
592 // thread is suspended
593 *bits |= 0x00000400;
594 return true;
595 }
596
597 // Now that we no longer do hard suspends of threads running
598 // native code, the target thread can be changing thread state
599 // while we are in this routine:
600 //
601 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
602 //
603 // We save a copy of the thread state as observed at this moment
604 // and make our decision about suspend completeness based on the
605 // copy. This closes the race where the thread state is seen as
606 // _thread_in_native_trans in the if-thread_blocked check, but is
607 // seen as _thread_blocked in if-thread_in_native_trans check.
608 JavaThreadState save_state = thread_state();
609
610 if (save_state == _thread_blocked && is_suspend_equivalent()) {
611 // If the thread's state is _thread_blocked and this blocking
612 // condition is known to be equivalent to a suspend, then we can
613 // consider the thread to be externally suspended. This means that
614 // the code that sets _thread_blocked has been modified to do
615 // self-suspension if the blocking condition releases. We also
616 // used to check for CONDVAR_WAIT here, but that is now covered by
617 // the _thread_blocked with self-suspension check.
618 //
619 // Return true since we wouldn't be here unless there was still an
620 // external suspend request.
621 *bits |= 0x00001000;
622 return true;
623 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
624 // Threads running native code will self-suspend on native==>VM/Java
625 // transitions. If its stack is walkable (should always be the case
626 // unless this function is called before the actual java_suspend()
627 // call), then the wait is done.
628 *bits |= 0x00002000;
629 return true;
630 } else if (!called_by_wait && !did_trans_retry &&
631 save_state == _thread_in_native_trans &&
632 frame_anchor()->walkable()) {
633 // The thread is transitioning from thread_in_native to another
634 // thread state. check_safepoint_and_suspend_for_native_trans()
635 // will force the thread to self-suspend. If it hasn't gotten
636 // there yet we may have caught the thread in-between the native
637 // code check above and the self-suspend. Lucky us. If we were
638 // called by wait_for_ext_suspend_completion(), then it
639 // will be doing the retries so we don't have to.
640 //
641 // Since we use the saved thread state in the if-statement above,
642 // there is a chance that the thread has already transitioned to
643 // _thread_blocked by the time we get here. In that case, we will
644 // make a single unnecessary pass through the logic below. This
645 // doesn't hurt anything since we still do the trans retry.
646
647 *bits |= 0x00004000;
648
649 // Once the thread leaves thread_in_native_trans for another
650 // thread state, we break out of this retry loop. We shouldn't
651 // need this flag to prevent us from getting back here, but
652 // sometimes paranoia is good.
653 did_trans_retry = true;
654
655 // We wait for the thread to transition to a more usable state.
656 for (int i = 1; i <= SuspendRetryCount; i++) {
657 // We used to do an "os::yield_all(i)" call here with the intention
658 // that yielding would increase on each retry. However, the parameter
659 // is ignored on Linux which means the yield didn't scale up. Waiting
660 // on the SR_lock below provides a much more predictable scale up for
661 // the delay. It also provides a simple/direct point to check for any
662 // safepoint requests from the VMThread
663
664 // temporarily drops SR_lock while doing wait with safepoint check
665 // (if we're a JavaThread - the WatcherThread can also call this)
666 // and increase delay with each retry
667 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
668
669 // check the actual thread state instead of what we saved above
670 if (thread_state() != _thread_in_native_trans) {
671 // the thread has transitioned to another thread state so
672 // try all the checks (except this one) one more time.
673 do_trans_retry = true;
674 break;
675 }
676 } // end retry loop
677
678
679 }
680 } while (do_trans_retry);
681
682 *bits |= 0x00000010;
683 return false;
684 }
685
686 // Wait for an external suspend request to complete (or be cancelled).
687 // Returns true if the thread is externally suspended and false otherwise.
688 //
689 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
690 uint32_t *bits) {
691 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
692 false /* !called_by_wait */, bits);
693
694 // local flag copies to minimize SR_lock hold time
695 bool is_suspended;
696 bool pending;
697 uint32_t reset_bits;
698
699 // set a marker so is_ext_suspend_completed() knows we are the caller
700 *bits |= 0x00010000;
701
702 // We use reset_bits to reinitialize the bits value at the top of
703 // each retry loop. This allows the caller to make use of any
704 // unused bits for their own marking purposes.
705 reset_bits = *bits;
706
707 {
708 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
709 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
710 delay, bits);
711 pending = is_external_suspend();
712 }
713 // must release SR_lock to allow suspension to complete
714
715 if (!pending) {
716 // A cancelled suspend request is the only false return from
717 // is_ext_suspend_completed() that keeps us from entering the
718 // retry loop.
719 *bits |= 0x00020000;
720 return false;
721 }
722
723 if (is_suspended) {
724 *bits |= 0x00040000;
725 return true;
726 }
727
728 for (int i = 1; i <= retries; i++) {
729 *bits = reset_bits; // reinit to only track last retry
730
731 // We used to do an "os::yield_all(i)" call here with the intention
732 // that yielding would increase on each retry. However, the parameter
733 // is ignored on Linux which means the yield didn't scale up. Waiting
734 // on the SR_lock below provides a much more predictable scale up for
735 // the delay. It also provides a simple/direct point to check for any
736 // safepoint requests from the VMThread
737
738 {
739 MutexLocker ml(SR_lock());
740 // wait with safepoint check (if we're a JavaThread - the WatcherThread
741 // can also call this) and increase delay with each retry
742 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
743
744 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
745 delay, bits);
746
747 // It is possible for the external suspend request to be cancelled
748 // (by a resume) before the actual suspend operation is completed.
749 // Refresh our local copy to see if we still need to wait.
750 pending = is_external_suspend();
751 }
752
753 if (!pending) {
754 // A cancelled suspend request is the only false return from
755 // is_ext_suspend_completed() that keeps us from staying in the
756 // retry loop.
757 *bits |= 0x00080000;
758 return false;
759 }
760
761 if (is_suspended) {
762 *bits |= 0x00100000;
763 return true;
764 }
765 } // end retry loop
766
767 // thread did not suspend after all our retries
768 *bits |= 0x00200000;
769 return false;
770 }
771
772 // Called from API entry points which perform stack walking. If the
773 // associated JavaThread is the current thread, then wait_for_suspend
774 // is not used. Otherwise, it determines if we should wait for the
775 // "other" thread to complete external suspension. (NOTE: in future
776 // releases the suspension mechanism should be reimplemented so this
777 // is not necessary.)
778 //
779 bool
780 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
781 if (this != JavaThread::current()) {
782 // "other" threads require special handling.
783 if (wait_for_suspend) {
784 // We are allowed to wait for the external suspend to complete
785 // so give the other thread a chance to get suspended.
786 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
787 SuspendRetryDelay, bits)) {
788 // Didn't make it so let the caller know.
789 return false;
790 }
791 }
792 // We aren't allowed to wait for the external suspend to complete
793 // so if the other thread isn't externally suspended we need to
794 // let the caller know.
795 else if (!is_ext_suspend_completed_with_lock(bits)) {
796 return false;
797 }
798 }
799
800 return true;
801 }
802
803 #ifndef PRODUCT
804 void JavaThread::record_jump(address target, address instr, const char* file,
805 int line) {
806
807 // This should not need to be atomic as the only way for simultaneous
808 // updates is via interrupts. Even then this should be rare or non-existent
809 // and we don't care that much anyway.
810
811 int index = _jmp_ring_index;
812 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
813 _jmp_ring[index]._target = (intptr_t) target;
814 _jmp_ring[index]._instruction = (intptr_t) instr;
815 _jmp_ring[index]._file = file;
816 _jmp_ring[index]._line = line;
817 }
818 #endif // PRODUCT
819
820 void Thread::interrupt(Thread* thread) {
821 debug_only(check_for_dangling_thread_pointer(thread);)
822 os::interrupt(thread);
823 }
824
825 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
826 debug_only(check_for_dangling_thread_pointer(thread);)
827 // Note: If clear_interrupted==false, this simply fetches and
828 // returns the value of the field osthread()->interrupted().
829 return os::is_interrupted(thread, clear_interrupted);
830 }
831
832
833 // GC Support
834 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
835 int thread_parity = _oops_do_parity;
836 if (thread_parity != strong_roots_parity) {
837 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
838 if (res == thread_parity) {
839 return true;
840 } else {
841 guarantee(res == strong_roots_parity, "Or else what?");
842 return false;
843 }
844 }
845 return false;
846 }
847
848 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
849 active_handles()->oops_do(f);
850 // Do oop for ThreadShadow
851 f->do_oop((oop*)&_pending_exception);
852 handle_area()->oops_do(f);
853
854 if (MonitorInUseLists) {
855 // When using thread local monitor lists, we scan them here,
856 // and the remaining global monitors in ObjectSynchronizer::oops_do().
857 ObjectSynchronizer::thread_local_used_oops_do(this, f);
858 }
859 }
860
861 void Thread::metadata_handles_do(void f(Metadata*)) {
862 // Only walk the Handles in Thread.
863 if (metadata_handles() != NULL) {
864 for (int i = 0; i< metadata_handles()->length(); i++) {
865 f(metadata_handles()->at(i));
866 }
867 }
868 }
869
870 void Thread::print_on(outputStream* st, bool print_extended_info) const {
871 // get_priority assumes osthread initialized
872 if (osthread() != NULL) {
873 int os_prio;
874 if (os::get_native_priority(this, &os_prio) == OS_OK) {
875 st->print("os_prio=%d ", os_prio);
876 }
877
878 st->print("cpu=%.2fms ",
879 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
880 );
881 st->print("elapsed=%.2fs ",
882 _statistical_info.getElapsedTime() / 1000.0
883 );
884 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
885 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
886 st->print("allocated=" SIZE_FORMAT "%s ",
887 byte_size_in_proper_unit(allocated_bytes),
888 proper_unit_for_byte_size(allocated_bytes)
889 );
890 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
891 }
892
893 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
894 osthread()->print_on(st);
895 }
896 ThreadsSMRSupport::print_info_on(this, st);
897 st->print(" ");
898 debug_only(if (WizardMode) print_owned_locks_on(st);)
899 }
900
901 // Thread::print_on_error() is called by fatal error handler. Don't use
902 // any lock or allocate memory.
903 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
904 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
905
906 if (is_VM_thread()) { st->print("VMThread"); }
907 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
908 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
909 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
910 else { st->print("Thread"); }
911
912 if (is_Named_thread()) {
913 st->print(" \"%s\"", name());
914 }
915
916 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
917 p2i(stack_end()), p2i(stack_base()));
918
919 if (osthread()) {
920 st->print(" [id=%d]", osthread()->thread_id());
921 }
922
923 ThreadsSMRSupport::print_info_on(this, st);
924 }
925
926 void Thread::print_value_on(outputStream* st) const {
927 if (is_Named_thread()) {
928 st->print(" \"%s\" ", name());
929 }
930 st->print(INTPTR_FORMAT, p2i(this)); // print address
931 }
932
933 #ifdef ASSERT
934 void Thread::print_owned_locks_on(outputStream* st) const {
935 Monitor *cur = _owned_locks;
936 if (cur == NULL) {
937 st->print(" (no locks) ");
938 } else {
939 st->print_cr(" Locks owned:");
940 while (cur) {
941 cur->print_on(st);
942 cur = cur->next();
943 }
944 }
945 }
946
947 static int ref_use_count = 0;
948
949 bool Thread::owns_locks_but_compiled_lock() const {
950 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
951 if (cur != Compile_lock) return true;
952 }
953 return false;
954 }
955
956
957 #endif
958
959 #ifndef PRODUCT
960
961 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
962 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
963 // no locks which allow_vm_block's are held
964 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
965 // Check if current thread is allowed to block at a safepoint
966 if (!(_allow_safepoint_count == 0)) {
967 fatal("Possible safepoint reached by thread that does not allow it");
968 }
969 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
970 fatal("LEAF method calling lock?");
971 }
972
973 #ifdef ASSERT
974 if (potential_vm_operation && is_Java_thread()
975 && !Universe::is_bootstrapping()) {
976 // Make sure we do not hold any locks that the VM thread also uses.
977 // This could potentially lead to deadlocks
978 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
979 // Threads_lock is special, since the safepoint synchronization will not start before this is
980 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
981 // since it is used to transfer control between JavaThreads and the VMThread
982 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
983 if ((cur->allow_vm_block() &&
984 cur != Threads_lock &&
985 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
986 cur != VMOperationRequest_lock &&
987 cur != VMOperationQueue_lock) ||
988 cur->rank() == Mutex::special) {
989 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
990 }
991 }
992 }
993
994 if (GCALotAtAllSafepoints) {
995 // We could enter a safepoint here and thus have a gc
996 InterfaceSupport::check_gc_alot();
997 }
998 #endif
999 }
1000 #endif
1001
1002 bool Thread::is_in_stack(address adr) const {
1003 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1004 address end = os::current_stack_pointer();
1005 // Allow non Java threads to call this without stack_base
1006 if (_stack_base == NULL) return true;
1007 if (stack_base() >= adr && adr >= end) return true;
1008
1009 return false;
1010 }
1011
1012 bool Thread::is_in_usable_stack(address adr) const {
1013 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1014 size_t usable_stack_size = _stack_size - stack_guard_size;
1015
1016 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1017 }
1018
1019
1020 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1021 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1022 // used for compilation in the future. If that change is made, the need for these methods
1023 // should be revisited, and they should be removed if possible.
1024
1025 bool Thread::is_lock_owned(address adr) const {
1026 return on_local_stack(adr);
1027 }
1028
1029 bool Thread::set_as_starting_thread() {
1030 // NOTE: this must be called inside the main thread.
1031 return os::create_main_thread((JavaThread*)this);
1032 }
1033
1034 static void initialize_class(Symbol* class_name, TRAPS) {
1035 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1036 InstanceKlass::cast(klass)->initialize(CHECK);
1037 }
1038
1039
1040 // Creates the initial ThreadGroup
1041 static Handle create_initial_thread_group(TRAPS) {
1042 Handle system_instance = JavaCalls::construct_new_instance(
1043 SystemDictionary::ThreadGroup_klass(),
1044 vmSymbols::void_method_signature(),
1045 CHECK_NH);
1046 Universe::set_system_thread_group(system_instance());
1047
1048 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1049 Handle main_instance = JavaCalls::construct_new_instance(
1050 SystemDictionary::ThreadGroup_klass(),
1051 vmSymbols::threadgroup_string_void_signature(),
1052 system_instance,
1053 string,
1054 CHECK_NH);
1055 return main_instance;
1056 }
1057
1058 // Creates the initial Thread
1059 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1060 TRAPS) {
1061 InstanceKlass* ik = SystemDictionary::Thread_klass();
1062 assert(ik->is_initialized(), "must be");
1063 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1064
1065 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1066 // constructor calls Thread.current(), which must be set here for the
1067 // initial thread.
1068 java_lang_Thread::set_thread(thread_oop(), thread);
1069 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1070 thread->set_threadObj(thread_oop());
1071
1072 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1073
1074 JavaValue result(T_VOID);
1075 JavaCalls::call_special(&result, thread_oop,
1076 ik,
1077 vmSymbols::object_initializer_name(),
1078 vmSymbols::threadgroup_string_void_signature(),
1079 thread_group,
1080 string,
1081 CHECK_NULL);
1082 return thread_oop();
1083 }
1084
1085 char java_runtime_name[128] = "";
1086 char java_runtime_version[128] = "";
1087
1088 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1089 static const char* get_java_runtime_name(TRAPS) {
1090 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1091 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1092 fieldDescriptor fd;
1093 bool found = k != NULL &&
1094 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1095 vmSymbols::string_signature(), &fd);
1096 if (found) {
1097 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1098 if (name_oop == NULL) {
1099 return NULL;
1100 }
1101 const char* name = java_lang_String::as_utf8_string(name_oop,
1102 java_runtime_name,
1103 sizeof(java_runtime_name));
1104 return name;
1105 } else {
1106 return NULL;
1107 }
1108 }
1109
1110 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1111 static const char* get_java_runtime_version(TRAPS) {
1112 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1113 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1114 fieldDescriptor fd;
1115 bool found = k != NULL &&
1116 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1117 vmSymbols::string_signature(), &fd);
1118 if (found) {
1119 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1120 if (name_oop == NULL) {
1121 return NULL;
1122 }
1123 const char* name = java_lang_String::as_utf8_string(name_oop,
1124 java_runtime_version,
1125 sizeof(java_runtime_version));
1126 return name;
1127 } else {
1128 return NULL;
1129 }
1130 }
1131
1132 // General purpose hook into Java code, run once when the VM is initialized.
1133 // The Java library method itself may be changed independently from the VM.
1134 static void call_postVMInitHook(TRAPS) {
1135 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1136 if (klass != NULL) {
1137 JavaValue result(T_VOID);
1138 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1139 vmSymbols::void_method_signature(),
1140 CHECK);
1141 }
1142 }
1143
1144 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1145 bool daemon, TRAPS) {
1146 assert(thread_group.not_null(), "thread group should be specified");
1147 assert(threadObj() == NULL, "should only create Java thread object once");
1148
1149 InstanceKlass* ik = SystemDictionary::Thread_klass();
1150 assert(ik->is_initialized(), "must be");
1151 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1152
1153 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1154 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1155 // constructor calls Thread.current(), which must be set here.
1156 java_lang_Thread::set_thread(thread_oop(), this);
1157 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1158 set_threadObj(thread_oop());
1159
1160 JavaValue result(T_VOID);
1161 if (thread_name != NULL) {
1162 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1163 // Thread gets assigned specified name and null target
1164 JavaCalls::call_special(&result,
1165 thread_oop,
1166 ik,
1167 vmSymbols::object_initializer_name(),
1168 vmSymbols::threadgroup_string_void_signature(),
1169 thread_group,
1170 name,
1171 THREAD);
1172 } else {
1173 // Thread gets assigned name "Thread-nnn" and null target
1174 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1175 JavaCalls::call_special(&result,
1176 thread_oop,
1177 ik,
1178 vmSymbols::object_initializer_name(),
1179 vmSymbols::threadgroup_runnable_void_signature(),
1180 thread_group,
1181 Handle(),
1182 THREAD);
1183 }
1184
1185
1186 if (daemon) {
1187 java_lang_Thread::set_daemon(thread_oop());
1188 }
1189
1190 if (HAS_PENDING_EXCEPTION) {
1191 return;
1192 }
1193
1194 Klass* group = SystemDictionary::ThreadGroup_klass();
1195 Handle threadObj(THREAD, this->threadObj());
1196
1197 JavaCalls::call_special(&result,
1198 thread_group,
1199 group,
1200 vmSymbols::add_method_name(),
1201 vmSymbols::thread_void_signature(),
1202 threadObj, // Arg 1
1203 THREAD);
1204 }
1205
1206 // List of all NonJavaThreads and safe iteration over that list.
1207
1208 class NonJavaThread::List {
1209 public:
1210 NonJavaThread* volatile _head;
1211 SingleWriterSynchronizer _protect;
1212
1213 List() : _head(NULL), _protect() {}
1214 };
1215
1216 NonJavaThread::List NonJavaThread::_the_list;
1217
1218 NonJavaThread::Iterator::Iterator() :
1219 _protect_enter(_the_list._protect.enter()),
1220 _current(OrderAccess::load_acquire(&_the_list._head))
1221 {}
1222
1223 NonJavaThread::Iterator::~Iterator() {
1224 _the_list._protect.exit(_protect_enter);
1225 }
1226
1227 void NonJavaThread::Iterator::step() {
1228 assert(!end(), "precondition");
1229 _current = OrderAccess::load_acquire(&_current->_next);
1230 }
1231
1232 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1233 // Add this thread to _the_list.
1234 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1235 _next = _the_list._head;
1236 OrderAccess::release_store(&_the_list._head, this);
1237 }
1238
1239 NonJavaThread::~NonJavaThread() {
1240 // Remove this thread from _the_list.
1241 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1242 NonJavaThread* volatile* p = &_the_list._head;
1243 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1244 if (t == this) {
1245 *p = this->_next;
1246 // Wait for any in-progress iterators.
1247 _the_list._protect.synchronize();
1248 break;
1249 }
1250 }
1251 }
1252
1253 // NamedThread -- non-JavaThread subclasses with multiple
1254 // uniquely named instances should derive from this.
1255 NamedThread::NamedThread() :
1256 NonJavaThread(),
1257 _name(NULL),
1258 _processed_thread(NULL),
1259 _gc_id(GCId::undefined())
1260 {}
1261
1262 NamedThread::~NamedThread() {
1263 if (_name != NULL) {
1264 FREE_C_HEAP_ARRAY(char, _name);
1265 _name = NULL;
1266 }
1267 }
1268
1269 void NamedThread::set_name(const char* format, ...) {
1270 guarantee(_name == NULL, "Only get to set name once.");
1271 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1272 guarantee(_name != NULL, "alloc failure");
1273 va_list ap;
1274 va_start(ap, format);
1275 jio_vsnprintf(_name, max_name_len, format, ap);
1276 va_end(ap);
1277 }
1278
1279 void NamedThread::initialize_named_thread() {
1280 set_native_thread_name(name());
1281 }
1282
1283 void NamedThread::print_on(outputStream* st) const {
1284 st->print("\"%s\" ", name());
1285 Thread::print_on(st);
1286 st->cr();
1287 }
1288
1289
1290 // ======= WatcherThread ========
1291
1292 // The watcher thread exists to simulate timer interrupts. It should
1293 // be replaced by an abstraction over whatever native support for
1294 // timer interrupts exists on the platform.
1295
1296 WatcherThread* WatcherThread::_watcher_thread = NULL;
1297 bool WatcherThread::_startable = false;
1298 volatile bool WatcherThread::_should_terminate = false;
1299
1300 WatcherThread::WatcherThread() : NonJavaThread() {
1301 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1302 if (os::create_thread(this, os::watcher_thread)) {
1303 _watcher_thread = this;
1304
1305 // Set the watcher thread to the highest OS priority which should not be
1306 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1307 // is created. The only normal thread using this priority is the reference
1308 // handler thread, which runs for very short intervals only.
1309 // If the VMThread's priority is not lower than the WatcherThread profiling
1310 // will be inaccurate.
1311 os::set_priority(this, MaxPriority);
1312 if (!DisableStartThread) {
1313 os::start_thread(this);
1314 }
1315 }
1316 }
1317
1318 int WatcherThread::sleep() const {
1319 // The WatcherThread does not participate in the safepoint protocol
1320 // for the PeriodicTask_lock because it is not a JavaThread.
1321 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1322
1323 if (_should_terminate) {
1324 // check for termination before we do any housekeeping or wait
1325 return 0; // we did not sleep.
1326 }
1327
1328 // remaining will be zero if there are no tasks,
1329 // causing the WatcherThread to sleep until a task is
1330 // enrolled
1331 int remaining = PeriodicTask::time_to_wait();
1332 int time_slept = 0;
1333
1334 // we expect this to timeout - we only ever get unparked when
1335 // we should terminate or when a new task has been enrolled
1336 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1337
1338 jlong time_before_loop = os::javaTimeNanos();
1339
1340 while (true) {
1341 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1342 remaining);
1343 jlong now = os::javaTimeNanos();
1344
1345 if (remaining == 0) {
1346 // if we didn't have any tasks we could have waited for a long time
1347 // consider the time_slept zero and reset time_before_loop
1348 time_slept = 0;
1349 time_before_loop = now;
1350 } else {
1351 // need to recalculate since we might have new tasks in _tasks
1352 time_slept = (int) ((now - time_before_loop) / 1000000);
1353 }
1354
1355 // Change to task list or spurious wakeup of some kind
1356 if (timedout || _should_terminate) {
1357 break;
1358 }
1359
1360 remaining = PeriodicTask::time_to_wait();
1361 if (remaining == 0) {
1362 // Last task was just disenrolled so loop around and wait until
1363 // another task gets enrolled
1364 continue;
1365 }
1366
1367 remaining -= time_slept;
1368 if (remaining <= 0) {
1369 break;
1370 }
1371 }
1372
1373 return time_slept;
1374 }
1375
1376 void WatcherThread::run() {
1377 assert(this == watcher_thread(), "just checking");
1378
1379 this->record_stack_base_and_size();
1380 this->set_native_thread_name(this->name());
1381 this->set_active_handles(JNIHandleBlock::allocate_block());
1382 while (true) {
1383 assert(watcher_thread() == Thread::current(), "thread consistency check");
1384 assert(watcher_thread() == this, "thread consistency check");
1385
1386 // Calculate how long it'll be until the next PeriodicTask work
1387 // should be done, and sleep that amount of time.
1388 int time_waited = sleep();
1389
1390 if (VMError::is_error_reported()) {
1391 // A fatal error has happened, the error handler(VMError::report_and_die)
1392 // should abort JVM after creating an error log file. However in some
1393 // rare cases, the error handler itself might deadlock. Here periodically
1394 // check for error reporting timeouts, and if it happens, just proceed to
1395 // abort the VM.
1396
1397 // This code is in WatcherThread because WatcherThread wakes up
1398 // periodically so the fatal error handler doesn't need to do anything;
1399 // also because the WatcherThread is less likely to crash than other
1400 // threads.
1401
1402 for (;;) {
1403 // Note: we use naked sleep in this loop because we want to avoid using
1404 // any kind of VM infrastructure which may be broken at this point.
1405 if (VMError::check_timeout()) {
1406 // We hit error reporting timeout. Error reporting was interrupted and
1407 // will be wrapping things up now (closing files etc). Give it some more
1408 // time, then quit the VM.
1409 os::naked_short_sleep(200);
1410 // Print a message to stderr.
1411 fdStream err(defaultStream::output_fd());
1412 err.print_raw_cr("# [ timer expired, abort... ]");
1413 // skip atexit/vm_exit/vm_abort hooks
1414 os::die();
1415 }
1416
1417 // Wait a second, then recheck for timeout.
1418 os::naked_short_sleep(999);
1419 }
1420 }
1421
1422 if (_should_terminate) {
1423 // check for termination before posting the next tick
1424 break;
1425 }
1426
1427 PeriodicTask::real_time_tick(time_waited);
1428 }
1429
1430 // Signal that it is terminated
1431 {
1432 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1433 _watcher_thread = NULL;
1434 Terminator_lock->notify();
1435 }
1436 }
1437
1438 void WatcherThread::start() {
1439 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1440
1441 if (watcher_thread() == NULL && _startable) {
1442 _should_terminate = false;
1443 // Create the single instance of WatcherThread
1444 new WatcherThread();
1445 }
1446 }
1447
1448 void WatcherThread::make_startable() {
1449 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1450 _startable = true;
1451 }
1452
1453 void WatcherThread::stop() {
1454 {
1455 // Follow normal safepoint aware lock enter protocol since the
1456 // WatcherThread is stopped by another JavaThread.
1457 MutexLocker ml(PeriodicTask_lock);
1458 _should_terminate = true;
1459
1460 WatcherThread* watcher = watcher_thread();
1461 if (watcher != NULL) {
1462 // unpark the WatcherThread so it can see that it should terminate
1463 watcher->unpark();
1464 }
1465 }
1466
1467 MutexLocker mu(Terminator_lock);
1468
1469 while (watcher_thread() != NULL) {
1470 // This wait should make safepoint checks, wait without a timeout,
1471 // and wait as a suspend-equivalent condition.
1472 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1473 Mutex::_as_suspend_equivalent_flag);
1474 }
1475 }
1476
1477 void WatcherThread::unpark() {
1478 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1479 PeriodicTask_lock->notify();
1480 }
1481
1482 void WatcherThread::print_on(outputStream* st) const {
1483 st->print("\"%s\" ", name());
1484 Thread::print_on(st);
1485 st->cr();
1486 }
1487
1488 // ======= JavaThread ========
1489
1490 #if INCLUDE_JVMCI
1491
1492 jlong* JavaThread::_jvmci_old_thread_counters;
1493
1494 bool jvmci_counters_include(JavaThread* thread) {
1495 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1496 }
1497
1498 void JavaThread::collect_counters(typeArrayOop array) {
1499 if (JVMCICounterSize > 0) {
1500 JavaThreadIteratorWithHandle jtiwh;
1501 for (int i = 0; i < array->length(); i++) {
1502 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1503 }
1504 for (; JavaThread *tp = jtiwh.next(); ) {
1505 if (jvmci_counters_include(tp)) {
1506 for (int i = 0; i < array->length(); i++) {
1507 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1508 }
1509 }
1510 }
1511 }
1512 }
1513
1514 #endif // INCLUDE_JVMCI
1515
1516 // A JavaThread is a normal Java thread
1517
1518 void JavaThread::initialize() {
1519 // Initialize fields
1520
1521 set_saved_exception_pc(NULL);
1522 set_threadObj(NULL);
1523 _anchor.clear();
1524 set_entry_point(NULL);
1525 set_jni_functions(jni_functions());
1526 set_callee_target(NULL);
1527 set_vm_result(NULL);
1528 set_vm_result_2(NULL);
1529 set_vframe_array_head(NULL);
1530 set_vframe_array_last(NULL);
1531 set_deferred_locals(NULL);
1532 set_deopt_mark(NULL);
1533 set_deopt_compiled_method(NULL);
1534 clear_must_deopt_id();
1535 set_monitor_chunks(NULL);
1536 set_next(NULL);
1537 _on_thread_list = false;
1538 set_thread_state(_thread_new);
1539 _terminated = _not_terminated;
1540 _privileged_stack_top = NULL;
1541 _array_for_gc = NULL;
1542 _suspend_equivalent = false;
1543 _in_deopt_handler = 0;
1544 _doing_unsafe_access = false;
1545 _stack_guard_state = stack_guard_unused;
1546 #if INCLUDE_JVMCI
1547 _pending_monitorenter = false;
1548 _pending_deoptimization = -1;
1549 _pending_failed_speculation = 0;
1550 _pending_transfer_to_interpreter = false;
1551 _adjusting_comp_level = false;
1552 _in_retryable_allocation = false;
1553 _jvmci._alternate_call_target = NULL;
1554 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1555 if (JVMCICounterSize > 0) {
1556 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1557 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1558 } else {
1559 _jvmci_counters = NULL;
1560 }
1561 #endif // INCLUDE_JVMCI
1562 _reserved_stack_activation = NULL; // stack base not known yet
1563 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1564 _exception_pc = 0;
1565 _exception_handler_pc = 0;
1566 _is_method_handle_return = 0;
1567 _jvmti_thread_state= NULL;
1568 _should_post_on_exceptions_flag = JNI_FALSE;
1569 _interp_only_mode = 0;
1570 _special_runtime_exit_condition = _no_async_condition;
1571 _pending_async_exception = NULL;
1572 _thread_stat = NULL;
1573 _thread_stat = new ThreadStatistics();
1574 _blocked_on_compilation = false;
1575 _jni_active_critical = 0;
1576 _pending_jni_exception_check_fn = NULL;
1577 _do_not_unlock_if_synchronized = false;
1578 _cached_monitor_info = NULL;
1579 _parker = Parker::Allocate(this);
1580
1581 #ifndef PRODUCT
1582 _jmp_ring_index = 0;
1583 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1584 record_jump(NULL, NULL, NULL, 0);
1585 }
1586 #endif // PRODUCT
1587
1588 // Setup safepoint state info for this thread
1589 ThreadSafepointState::create(this);
1590
1591 debug_only(_java_call_counter = 0);
1592
1593 // JVMTI PopFrame support
1594 _popframe_condition = popframe_inactive;
1595 _popframe_preserved_args = NULL;
1596 _popframe_preserved_args_size = 0;
1597 _frames_to_pop_failed_realloc = 0;
1598
1599 if (SafepointMechanism::uses_thread_local_poll()) {
1600 SafepointMechanism::initialize_header(this);
1601 }
1602
1603 pd_initialize();
1604 }
1605
1606 JavaThread::JavaThread(bool is_attaching_via_jni) :
1607 Thread() {
1608 initialize();
1609 if (is_attaching_via_jni) {
1610 _jni_attach_state = _attaching_via_jni;
1611 } else {
1612 _jni_attach_state = _not_attaching_via_jni;
1613 }
1614 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1615 }
1616
1617 bool JavaThread::reguard_stack(address cur_sp) {
1618 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1619 && _stack_guard_state != stack_guard_reserved_disabled) {
1620 return true; // Stack already guarded or guard pages not needed.
1621 }
1622
1623 if (register_stack_overflow()) {
1624 // For those architectures which have separate register and
1625 // memory stacks, we must check the register stack to see if
1626 // it has overflowed.
1627 return false;
1628 }
1629
1630 // Java code never executes within the yellow zone: the latter is only
1631 // there to provoke an exception during stack banging. If java code
1632 // is executing there, either StackShadowPages should be larger, or
1633 // some exception code in c1, c2 or the interpreter isn't unwinding
1634 // when it should.
1635 guarantee(cur_sp > stack_reserved_zone_base(),
1636 "not enough space to reguard - increase StackShadowPages");
1637 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1638 enable_stack_yellow_reserved_zone();
1639 if (reserved_stack_activation() != stack_base()) {
1640 set_reserved_stack_activation(stack_base());
1641 }
1642 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1643 set_reserved_stack_activation(stack_base());
1644 enable_stack_reserved_zone();
1645 }
1646 return true;
1647 }
1648
1649 bool JavaThread::reguard_stack(void) {
1650 return reguard_stack(os::current_stack_pointer());
1651 }
1652
1653
1654 void JavaThread::block_if_vm_exited() {
1655 if (_terminated == _vm_exited) {
1656 // _vm_exited is set at safepoint, and Threads_lock is never released
1657 // we will block here forever
1658 Threads_lock->lock_without_safepoint_check();
1659 ShouldNotReachHere();
1660 }
1661 }
1662
1663
1664 // Remove this ifdef when C1 is ported to the compiler interface.
1665 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1666 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1667
1668 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1669 Thread() {
1670 initialize();
1671 _jni_attach_state = _not_attaching_via_jni;
1672 set_entry_point(entry_point);
1673 // Create the native thread itself.
1674 // %note runtime_23
1675 os::ThreadType thr_type = os::java_thread;
1676 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1677 os::java_thread;
1678 os::create_thread(this, thr_type, stack_sz);
1679 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1680 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1681 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1682 // the exception consists of creating the exception object & initializing it, initialization
1683 // will leave the VM via a JavaCall and then all locks must be unlocked).
1684 //
1685 // The thread is still suspended when we reach here. Thread must be explicit started
1686 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1687 // by calling Threads:add. The reason why this is not done here, is because the thread
1688 // object must be fully initialized (take a look at JVM_Start)
1689 }
1690
1691 JavaThread::~JavaThread() {
1692
1693 // JSR166 -- return the parker to the free list
1694 Parker::Release(_parker);
1695 _parker = NULL;
1696
1697 // Free any remaining previous UnrollBlock
1698 vframeArray* old_array = vframe_array_last();
1699
1700 if (old_array != NULL) {
1701 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1702 old_array->set_unroll_block(NULL);
1703 delete old_info;
1704 delete old_array;
1705 }
1706
1707 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1708 if (deferred != NULL) {
1709 // This can only happen if thread is destroyed before deoptimization occurs.
1710 assert(deferred->length() != 0, "empty array!");
1711 do {
1712 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1713 deferred->remove_at(0);
1714 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1715 delete dlv;
1716 } while (deferred->length() != 0);
1717 delete deferred;
1718 }
1719
1720 // All Java related clean up happens in exit
1721 ThreadSafepointState::destroy(this);
1722 if (_thread_stat != NULL) delete _thread_stat;
1723
1724 #if INCLUDE_JVMCI
1725 if (JVMCICounterSize > 0) {
1726 if (jvmci_counters_include(this)) {
1727 for (int i = 0; i < JVMCICounterSize; i++) {
1728 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1729 }
1730 }
1731 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1732 }
1733 #endif // INCLUDE_JVMCI
1734 }
1735
1736
1737 // The first routine called by a new Java thread
1738 void JavaThread::run() {
1739 // initialize thread-local alloc buffer related fields
1740 this->initialize_tlab();
1741
1742 // used to test validity of stack trace backs
1743 this->record_base_of_stack_pointer();
1744
1745 // Record real stack base and size.
1746 this->record_stack_base_and_size();
1747
1748 this->create_stack_guard_pages();
1749
1750 this->cache_global_variables();
1751
1752 // Thread is now sufficient initialized to be handled by the safepoint code as being
1753 // in the VM. Change thread state from _thread_new to _thread_in_vm
1754 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1755
1756 assert(JavaThread::current() == this, "sanity check");
1757 assert(!Thread::current()->owns_locks(), "sanity check");
1758
1759 DTRACE_THREAD_PROBE(start, this);
1760
1761 // This operation might block. We call that after all safepoint checks for a new thread has
1762 // been completed.
1763 this->set_active_handles(JNIHandleBlock::allocate_block());
1764
1765 if (JvmtiExport::should_post_thread_life()) {
1766 JvmtiExport::post_thread_start(this);
1767 }
1768
1769 EventThreadStart event;
1770 if (event.should_commit()) {
1771 event.set_thread(JFR_THREAD_ID(this));
1772 event.commit();
1773 }
1774
1775 // We call another function to do the rest so we are sure that the stack addresses used
1776 // from there will be lower than the stack base just computed
1777 thread_main_inner();
1778
1779 // Note, thread is no longer valid at this point!
1780 }
1781
1782
1783 void JavaThread::thread_main_inner() {
1784 assert(JavaThread::current() == this, "sanity check");
1785 assert(this->threadObj() != NULL, "just checking");
1786
1787 // Execute thread entry point unless this thread has a pending exception
1788 // or has been stopped before starting.
1789 // Note: Due to JVM_StopThread we can have pending exceptions already!
1790 if (!this->has_pending_exception() &&
1791 !java_lang_Thread::is_stillborn(this->threadObj())) {
1792 {
1793 ResourceMark rm(this);
1794 this->set_native_thread_name(this->get_thread_name());
1795 }
1796 HandleMark hm(this);
1797 this->entry_point()(this, this);
1798 }
1799
1800 DTRACE_THREAD_PROBE(stop, this);
1801
1802 this->exit(false);
1803 this->smr_delete();
1804 }
1805
1806
1807 static void ensure_join(JavaThread* thread) {
1808 // We do not need to grab the Threads_lock, since we are operating on ourself.
1809 Handle threadObj(thread, thread->threadObj());
1810 assert(threadObj.not_null(), "java thread object must exist");
1811 ObjectLocker lock(threadObj, thread);
1812 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1813 thread->clear_pending_exception();
1814 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1815 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1816 // Clear the native thread instance - this makes isAlive return false and allows the join()
1817 // to complete once we've done the notify_all below
1818 java_lang_Thread::set_thread(threadObj(), NULL);
1819 lock.notify_all(thread);
1820 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1821 thread->clear_pending_exception();
1822 }
1823
1824
1825 // For any new cleanup additions, please check to see if they need to be applied to
1826 // cleanup_failed_attach_current_thread as well.
1827 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1828 assert(this == JavaThread::current(), "thread consistency check");
1829
1830 elapsedTimer _timer_exit_phase1;
1831 elapsedTimer _timer_exit_phase2;
1832 elapsedTimer _timer_exit_phase3;
1833 elapsedTimer _timer_exit_phase4;
1834
1835 if (log_is_enabled(Debug, os, thread, timer)) {
1836 _timer_exit_phase1.start();
1837 }
1838
1839 HandleMark hm(this);
1840 Handle uncaught_exception(this, this->pending_exception());
1841 this->clear_pending_exception();
1842 Handle threadObj(this, this->threadObj());
1843 assert(threadObj.not_null(), "Java thread object should be created");
1844
1845 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1846 {
1847 EXCEPTION_MARK;
1848
1849 CLEAR_PENDING_EXCEPTION;
1850 }
1851 if (!destroy_vm) {
1852 if (uncaught_exception.not_null()) {
1853 EXCEPTION_MARK;
1854 // Call method Thread.dispatchUncaughtException().
1855 Klass* thread_klass = SystemDictionary::Thread_klass();
1856 JavaValue result(T_VOID);
1857 JavaCalls::call_virtual(&result,
1858 threadObj, thread_klass,
1859 vmSymbols::dispatchUncaughtException_name(),
1860 vmSymbols::throwable_void_signature(),
1861 uncaught_exception,
1862 THREAD);
1863 if (HAS_PENDING_EXCEPTION) {
1864 ResourceMark rm(this);
1865 jio_fprintf(defaultStream::error_stream(),
1866 "\nException: %s thrown from the UncaughtExceptionHandler"
1867 " in thread \"%s\"\n",
1868 pending_exception()->klass()->external_name(),
1869 get_thread_name());
1870 CLEAR_PENDING_EXCEPTION;
1871 }
1872 }
1873
1874 // Called before the java thread exit since we want to read info
1875 // from java_lang_Thread object
1876 EventThreadEnd event;
1877 if (event.should_commit()) {
1878 event.set_thread(JFR_THREAD_ID(this));
1879 event.commit();
1880 }
1881
1882 // Call after last event on thread
1883 JFR_ONLY(Jfr::on_thread_exit(this);)
1884
1885 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1886 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1887 // is deprecated anyhow.
1888 if (!is_Compiler_thread()) {
1889 int count = 3;
1890 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1891 EXCEPTION_MARK;
1892 JavaValue result(T_VOID);
1893 Klass* thread_klass = SystemDictionary::Thread_klass();
1894 JavaCalls::call_virtual(&result,
1895 threadObj, thread_klass,
1896 vmSymbols::exit_method_name(),
1897 vmSymbols::void_method_signature(),
1898 THREAD);
1899 CLEAR_PENDING_EXCEPTION;
1900 }
1901 }
1902 // notify JVMTI
1903 if (JvmtiExport::should_post_thread_life()) {
1904 JvmtiExport::post_thread_end(this);
1905 }
1906
1907 // We have notified the agents that we are exiting, before we go on,
1908 // we must check for a pending external suspend request and honor it
1909 // in order to not surprise the thread that made the suspend request.
1910 while (true) {
1911 {
1912 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1913 if (!is_external_suspend()) {
1914 set_terminated(_thread_exiting);
1915 ThreadService::current_thread_exiting(this);
1916 break;
1917 }
1918 // Implied else:
1919 // Things get a little tricky here. We have a pending external
1920 // suspend request, but we are holding the SR_lock so we
1921 // can't just self-suspend. So we temporarily drop the lock
1922 // and then self-suspend.
1923 }
1924
1925 ThreadBlockInVM tbivm(this);
1926 java_suspend_self();
1927
1928 // We're done with this suspend request, but we have to loop around
1929 // and check again. Eventually we will get SR_lock without a pending
1930 // external suspend request and will be able to mark ourselves as
1931 // exiting.
1932 }
1933 // no more external suspends are allowed at this point
1934 } else {
1935 // before_exit() has already posted JVMTI THREAD_END events
1936 }
1937
1938 if (log_is_enabled(Debug, os, thread, timer)) {
1939 _timer_exit_phase1.stop();
1940 _timer_exit_phase2.start();
1941 }
1942 // Notify waiters on thread object. This has to be done after exit() is called
1943 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1944 // group should have the destroyed bit set before waiters are notified).
1945 ensure_join(this);
1946 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1947
1948 if (log_is_enabled(Debug, os, thread, timer)) {
1949 _timer_exit_phase2.stop();
1950 _timer_exit_phase3.start();
1951 }
1952 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1953 // held by this thread must be released. The spec does not distinguish
1954 // between JNI-acquired and regular Java monitors. We can only see
1955 // regular Java monitors here if monitor enter-exit matching is broken.
1956 //
1957 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1958 // ObjectSynchronizer::release_monitors_owned_by_thread().
1959 if (exit_type == jni_detach) {
1960 // Sanity check even though JNI DetachCurrentThread() would have
1961 // returned JNI_ERR if there was a Java frame. JavaThread exit
1962 // should be done executing Java code by the time we get here.
1963 assert(!this->has_last_Java_frame(),
1964 "should not have a Java frame when detaching or exiting");
1965 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1966 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1967 }
1968
1969 // These things needs to be done while we are still a Java Thread. Make sure that thread
1970 // is in a consistent state, in case GC happens
1971 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1972
1973 if (active_handles() != NULL) {
1974 JNIHandleBlock* block = active_handles();
1975 set_active_handles(NULL);
1976 JNIHandleBlock::release_block(block);
1977 }
1978
1979 if (free_handle_block() != NULL) {
1980 JNIHandleBlock* block = free_handle_block();
1981 set_free_handle_block(NULL);
1982 JNIHandleBlock::release_block(block);
1983 }
1984
1985 // These have to be removed while this is still a valid thread.
1986 remove_stack_guard_pages();
1987
1988 if (UseTLAB) {
1989 tlab().retire();
1990 }
1991
1992 if (JvmtiEnv::environments_might_exist()) {
1993 JvmtiExport::cleanup_thread(this);
1994 }
1995
1996 // We must flush any deferred card marks and other various GC barrier
1997 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1998 // before removing a thread from the list of active threads.
1999 BarrierSet::barrier_set()->on_thread_detach(this);
2000
2001 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2002 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2003 os::current_thread_id());
2004
2005 if (log_is_enabled(Debug, os, thread, timer)) {
2006 _timer_exit_phase3.stop();
2007 _timer_exit_phase4.start();
2008 }
2009 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2010 Threads::remove(this);
2011
2012 if (log_is_enabled(Debug, os, thread, timer)) {
2013 _timer_exit_phase4.stop();
2014 ResourceMark rm(this);
2015 log_debug(os, thread, timer)("name='%s'"
2016 ", exit-phase1=" JLONG_FORMAT
2017 ", exit-phase2=" JLONG_FORMAT
2018 ", exit-phase3=" JLONG_FORMAT
2019 ", exit-phase4=" JLONG_FORMAT,
2020 get_thread_name(),
2021 _timer_exit_phase1.milliseconds(),
2022 _timer_exit_phase2.milliseconds(),
2023 _timer_exit_phase3.milliseconds(),
2024 _timer_exit_phase4.milliseconds());
2025 }
2026 }
2027
2028 void JavaThread::cleanup_failed_attach_current_thread() {
2029 if (active_handles() != NULL) {
2030 JNIHandleBlock* block = active_handles();
2031 set_active_handles(NULL);
2032 JNIHandleBlock::release_block(block);
2033 }
2034
2035 if (free_handle_block() != NULL) {
2036 JNIHandleBlock* block = free_handle_block();
2037 set_free_handle_block(NULL);
2038 JNIHandleBlock::release_block(block);
2039 }
2040
2041 // These have to be removed while this is still a valid thread.
2042 remove_stack_guard_pages();
2043
2044 if (UseTLAB) {
2045 tlab().retire();
2046 }
2047
2048 BarrierSet::barrier_set()->on_thread_detach(this);
2049
2050 Threads::remove(this);
2051 this->smr_delete();
2052 }
2053
2054 JavaThread* JavaThread::active() {
2055 Thread* thread = Thread::current();
2056 if (thread->is_Java_thread()) {
2057 return (JavaThread*) thread;
2058 } else {
2059 assert(thread->is_VM_thread(), "this must be a vm thread");
2060 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2061 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2062 assert(ret->is_Java_thread(), "must be a Java thread");
2063 return ret;
2064 }
2065 }
2066
2067 bool JavaThread::is_lock_owned(address adr) const {
2068 if (Thread::is_lock_owned(adr)) return true;
2069
2070 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2071 if (chunk->contains(adr)) return true;
2072 }
2073
2074 return false;
2075 }
2076
2077
2078 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2079 chunk->set_next(monitor_chunks());
2080 set_monitor_chunks(chunk);
2081 }
2082
2083 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2084 guarantee(monitor_chunks() != NULL, "must be non empty");
2085 if (monitor_chunks() == chunk) {
2086 set_monitor_chunks(chunk->next());
2087 } else {
2088 MonitorChunk* prev = monitor_chunks();
2089 while (prev->next() != chunk) prev = prev->next();
2090 prev->set_next(chunk->next());
2091 }
2092 }
2093
2094 // JVM support.
2095
2096 // Note: this function shouldn't block if it's called in
2097 // _thread_in_native_trans state (such as from
2098 // check_special_condition_for_native_trans()).
2099 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2100
2101 if (has_last_Java_frame() && has_async_condition()) {
2102 // If we are at a polling page safepoint (not a poll return)
2103 // then we must defer async exception because live registers
2104 // will be clobbered by the exception path. Poll return is
2105 // ok because the call we a returning from already collides
2106 // with exception handling registers and so there is no issue.
2107 // (The exception handling path kills call result registers but
2108 // this is ok since the exception kills the result anyway).
2109
2110 if (is_at_poll_safepoint()) {
2111 // if the code we are returning to has deoptimized we must defer
2112 // the exception otherwise live registers get clobbered on the
2113 // exception path before deoptimization is able to retrieve them.
2114 //
2115 RegisterMap map(this, false);
2116 frame caller_fr = last_frame().sender(&map);
2117 assert(caller_fr.is_compiled_frame(), "what?");
2118 if (caller_fr.is_deoptimized_frame()) {
2119 log_info(exceptions)("deferred async exception at compiled safepoint");
2120 return;
2121 }
2122 }
2123 }
2124
2125 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2126 if (condition == _no_async_condition) {
2127 // Conditions have changed since has_special_runtime_exit_condition()
2128 // was called:
2129 // - if we were here only because of an external suspend request,
2130 // then that was taken care of above (or cancelled) so we are done
2131 // - if we were here because of another async request, then it has
2132 // been cleared between the has_special_runtime_exit_condition()
2133 // and now so again we are done
2134 return;
2135 }
2136
2137 // Check for pending async. exception
2138 if (_pending_async_exception != NULL) {
2139 // Only overwrite an already pending exception, if it is not a threadDeath.
2140 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2141
2142 // We cannot call Exceptions::_throw(...) here because we cannot block
2143 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2144
2145 LogTarget(Info, exceptions) lt;
2146 if (lt.is_enabled()) {
2147 ResourceMark rm;
2148 LogStream ls(lt);
2149 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2150 if (has_last_Java_frame()) {
2151 frame f = last_frame();
2152 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2153 }
2154 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2155 }
2156 _pending_async_exception = NULL;
2157 clear_has_async_exception();
2158 }
2159 }
2160
2161 if (check_unsafe_error &&
2162 condition == _async_unsafe_access_error && !has_pending_exception()) {
2163 condition = _no_async_condition; // done
2164 switch (thread_state()) {
2165 case _thread_in_vm: {
2166 JavaThread* THREAD = this;
2167 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2168 }
2169 case _thread_in_native: {
2170 ThreadInVMfromNative tiv(this);
2171 JavaThread* THREAD = this;
2172 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2173 }
2174 case _thread_in_Java: {
2175 ThreadInVMfromJava tiv(this);
2176 JavaThread* THREAD = this;
2177 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2178 }
2179 default:
2180 ShouldNotReachHere();
2181 }
2182 }
2183
2184 assert(condition == _no_async_condition || has_pending_exception() ||
2185 (!check_unsafe_error && condition == _async_unsafe_access_error),
2186 "must have handled the async condition, if no exception");
2187 }
2188
2189 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2190 //
2191 // Check for pending external suspend. Internal suspend requests do
2192 // not use handle_special_runtime_exit_condition().
2193 // If JNIEnv proxies are allowed, don't self-suspend if the target
2194 // thread is not the current thread. In older versions of jdbx, jdbx
2195 // threads could call into the VM with another thread's JNIEnv so we
2196 // can be here operating on behalf of a suspended thread (4432884).
2197 bool do_self_suspend = is_external_suspend_with_lock();
2198 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2199 //
2200 // Because thread is external suspended the safepoint code will count
2201 // thread as at a safepoint. This can be odd because we can be here
2202 // as _thread_in_Java which would normally transition to _thread_blocked
2203 // at a safepoint. We would like to mark the thread as _thread_blocked
2204 // before calling java_suspend_self like all other callers of it but
2205 // we must then observe proper safepoint protocol. (We can't leave
2206 // _thread_blocked with a safepoint in progress). However we can be
2207 // here as _thread_in_native_trans so we can't use a normal transition
2208 // constructor/destructor pair because they assert on that type of
2209 // transition. We could do something like:
2210 //
2211 // JavaThreadState state = thread_state();
2212 // set_thread_state(_thread_in_vm);
2213 // {
2214 // ThreadBlockInVM tbivm(this);
2215 // java_suspend_self()
2216 // }
2217 // set_thread_state(_thread_in_vm_trans);
2218 // if (safepoint) block;
2219 // set_thread_state(state);
2220 //
2221 // but that is pretty messy. Instead we just go with the way the
2222 // code has worked before and note that this is the only path to
2223 // java_suspend_self that doesn't put the thread in _thread_blocked
2224 // mode.
2225
2226 frame_anchor()->make_walkable(this);
2227 java_suspend_self();
2228
2229 // We might be here for reasons in addition to the self-suspend request
2230 // so check for other async requests.
2231 }
2232
2233 if (check_asyncs) {
2234 check_and_handle_async_exceptions();
2235 }
2236
2237 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2238 }
2239
2240 void JavaThread::send_thread_stop(oop java_throwable) {
2241 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2242 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2243 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2244
2245 // Do not throw asynchronous exceptions against the compiler thread
2246 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2247 if (!can_call_java()) return;
2248
2249 {
2250 // Actually throw the Throwable against the target Thread - however
2251 // only if there is no thread death exception installed already.
2252 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2253 // If the topmost frame is a runtime stub, then we are calling into
2254 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2255 // must deoptimize the caller before continuing, as the compiled exception handler table
2256 // may not be valid
2257 if (has_last_Java_frame()) {
2258 frame f = last_frame();
2259 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2260 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2261 RegisterMap reg_map(this, UseBiasedLocking);
2262 frame compiled_frame = f.sender(®_map);
2263 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2264 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2265 }
2266 }
2267 }
2268
2269 // Set async. pending exception in thread.
2270 set_pending_async_exception(java_throwable);
2271
2272 if (log_is_enabled(Info, exceptions)) {
2273 ResourceMark rm;
2274 log_info(exceptions)("Pending Async. exception installed of type: %s",
2275 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2276 }
2277 // for AbortVMOnException flag
2278 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2279 }
2280 }
2281
2282
2283 // Interrupt thread so it will wake up from a potential wait()
2284 Thread::interrupt(this);
2285 }
2286
2287 // External suspension mechanism.
2288 //
2289 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2290 // to any VM_locks and it is at a transition
2291 // Self-suspension will happen on the transition out of the vm.
2292 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2293 //
2294 // Guarantees on return:
2295 // + Target thread will not execute any new bytecode (that's why we need to
2296 // force a safepoint)
2297 // + Target thread will not enter any new monitors
2298 //
2299 void JavaThread::java_suspend() {
2300 ThreadsListHandle tlh;
2301 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2302 return;
2303 }
2304
2305 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2306 if (!is_external_suspend()) {
2307 // a racing resume has cancelled us; bail out now
2308 return;
2309 }
2310
2311 // suspend is done
2312 uint32_t debug_bits = 0;
2313 // Warning: is_ext_suspend_completed() may temporarily drop the
2314 // SR_lock to allow the thread to reach a stable thread state if
2315 // it is currently in a transient thread state.
2316 if (is_ext_suspend_completed(false /* !called_by_wait */,
2317 SuspendRetryDelay, &debug_bits)) {
2318 return;
2319 }
2320 }
2321
2322 VM_ThreadSuspend vm_suspend;
2323 VMThread::execute(&vm_suspend);
2324 }
2325
2326 // Part II of external suspension.
2327 // A JavaThread self suspends when it detects a pending external suspend
2328 // request. This is usually on transitions. It is also done in places
2329 // where continuing to the next transition would surprise the caller,
2330 // e.g., monitor entry.
2331 //
2332 // Returns the number of times that the thread self-suspended.
2333 //
2334 // Note: DO NOT call java_suspend_self() when you just want to block current
2335 // thread. java_suspend_self() is the second stage of cooperative
2336 // suspension for external suspend requests and should only be used
2337 // to complete an external suspend request.
2338 //
2339 int JavaThread::java_suspend_self() {
2340 int ret = 0;
2341
2342 // we are in the process of exiting so don't suspend
2343 if (is_exiting()) {
2344 clear_external_suspend();
2345 return ret;
2346 }
2347
2348 assert(_anchor.walkable() ||
2349 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2350 "must have walkable stack");
2351
2352 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2353
2354 assert(!this->is_ext_suspended(),
2355 "a thread trying to self-suspend should not already be suspended");
2356
2357 if (this->is_suspend_equivalent()) {
2358 // If we are self-suspending as a result of the lifting of a
2359 // suspend equivalent condition, then the suspend_equivalent
2360 // flag is not cleared until we set the ext_suspended flag so
2361 // that wait_for_ext_suspend_completion() returns consistent
2362 // results.
2363 this->clear_suspend_equivalent();
2364 }
2365
2366 // A racing resume may have cancelled us before we grabbed SR_lock
2367 // above. Or another external suspend request could be waiting for us
2368 // by the time we return from SR_lock()->wait(). The thread
2369 // that requested the suspension may already be trying to walk our
2370 // stack and if we return now, we can change the stack out from under
2371 // it. This would be a "bad thing (TM)" and cause the stack walker
2372 // to crash. We stay self-suspended until there are no more pending
2373 // external suspend requests.
2374 while (is_external_suspend()) {
2375 ret++;
2376 this->set_ext_suspended();
2377
2378 // _ext_suspended flag is cleared by java_resume()
2379 while (is_ext_suspended()) {
2380 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2381 }
2382 }
2383
2384 return ret;
2385 }
2386
2387 #ifdef ASSERT
2388 // Verify the JavaThread has not yet been published in the Threads::list, and
2389 // hence doesn't need protection from concurrent access at this stage.
2390 void JavaThread::verify_not_published() {
2391 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2392 // since an unpublished JavaThread doesn't participate in the
2393 // Thread-SMR protocol for keeping a ThreadsList alive.
2394 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2395 }
2396 #endif
2397
2398 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2399 // progress or when _suspend_flags is non-zero.
2400 // Current thread needs to self-suspend if there is a suspend request and/or
2401 // block if a safepoint is in progress.
2402 // Async exception ISN'T checked.
2403 // Note only the ThreadInVMfromNative transition can call this function
2404 // directly and when thread state is _thread_in_native_trans
2405 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2406 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2407
2408 JavaThread *curJT = JavaThread::current();
2409 bool do_self_suspend = thread->is_external_suspend();
2410
2411 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2412
2413 // If JNIEnv proxies are allowed, don't self-suspend if the target
2414 // thread is not the current thread. In older versions of jdbx, jdbx
2415 // threads could call into the VM with another thread's JNIEnv so we
2416 // can be here operating on behalf of a suspended thread (4432884).
2417 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2418 JavaThreadState state = thread->thread_state();
2419
2420 // We mark this thread_blocked state as a suspend-equivalent so
2421 // that a caller to is_ext_suspend_completed() won't be confused.
2422 // The suspend-equivalent state is cleared by java_suspend_self().
2423 thread->set_suspend_equivalent();
2424
2425 // If the safepoint code sees the _thread_in_native_trans state, it will
2426 // wait until the thread changes to other thread state. There is no
2427 // guarantee on how soon we can obtain the SR_lock and complete the
2428 // self-suspend request. It would be a bad idea to let safepoint wait for
2429 // too long. Temporarily change the state to _thread_blocked to
2430 // let the VM thread know that this thread is ready for GC. The problem
2431 // of changing thread state is that safepoint could happen just after
2432 // java_suspend_self() returns after being resumed, and VM thread will
2433 // see the _thread_blocked state. We must check for safepoint
2434 // after restoring the state and make sure we won't leave while a safepoint
2435 // is in progress.
2436 thread->set_thread_state(_thread_blocked);
2437 thread->java_suspend_self();
2438 thread->set_thread_state(state);
2439
2440 InterfaceSupport::serialize_thread_state_with_handler(thread);
2441 }
2442
2443 SafepointMechanism::block_if_requested(curJT);
2444
2445 if (thread->is_deopt_suspend()) {
2446 thread->clear_deopt_suspend();
2447 RegisterMap map(thread, false);
2448 frame f = thread->last_frame();
2449 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2450 f = f.sender(&map);
2451 }
2452 if (f.id() == thread->must_deopt_id()) {
2453 thread->clear_must_deopt_id();
2454 f.deoptimize(thread);
2455 } else {
2456 fatal("missed deoptimization!");
2457 }
2458 }
2459
2460 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2461 }
2462
2463 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2464 // progress or when _suspend_flags is non-zero.
2465 // Current thread needs to self-suspend if there is a suspend request and/or
2466 // block if a safepoint is in progress.
2467 // Also check for pending async exception (not including unsafe access error).
2468 // Note only the native==>VM/Java barriers can call this function and when
2469 // thread state is _thread_in_native_trans.
2470 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2471 check_safepoint_and_suspend_for_native_trans(thread);
2472
2473 if (thread->has_async_exception()) {
2474 // We are in _thread_in_native_trans state, don't handle unsafe
2475 // access error since that may block.
2476 thread->check_and_handle_async_exceptions(false);
2477 }
2478 }
2479
2480 // This is a variant of the normal
2481 // check_special_condition_for_native_trans with slightly different
2482 // semantics for use by critical native wrappers. It does all the
2483 // normal checks but also performs the transition back into
2484 // thread_in_Java state. This is required so that critical natives
2485 // can potentially block and perform a GC if they are the last thread
2486 // exiting the GCLocker.
2487 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2488 check_special_condition_for_native_trans(thread);
2489
2490 // Finish the transition
2491 thread->set_thread_state(_thread_in_Java);
2492
2493 if (thread->do_critical_native_unlock()) {
2494 ThreadInVMfromJavaNoAsyncException tiv(thread);
2495 GCLocker::unlock_critical(thread);
2496 thread->clear_critical_native_unlock();
2497 }
2498 }
2499
2500 // We need to guarantee the Threads_lock here, since resumes are not
2501 // allowed during safepoint synchronization
2502 // Can only resume from an external suspension
2503 void JavaThread::java_resume() {
2504 assert_locked_or_safepoint(Threads_lock);
2505
2506 // Sanity check: thread is gone, has started exiting or the thread
2507 // was not externally suspended.
2508 ThreadsListHandle tlh;
2509 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2510 return;
2511 }
2512
2513 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2514
2515 clear_external_suspend();
2516
2517 if (is_ext_suspended()) {
2518 clear_ext_suspended();
2519 SR_lock()->notify_all();
2520 }
2521 }
2522
2523 size_t JavaThread::_stack_red_zone_size = 0;
2524 size_t JavaThread::_stack_yellow_zone_size = 0;
2525 size_t JavaThread::_stack_reserved_zone_size = 0;
2526 size_t JavaThread::_stack_shadow_zone_size = 0;
2527
2528 void JavaThread::create_stack_guard_pages() {
2529 if (!os::uses_stack_guard_pages() ||
2530 _stack_guard_state != stack_guard_unused ||
2531 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2532 log_info(os, thread)("Stack guard page creation for thread "
2533 UINTX_FORMAT " disabled", os::current_thread_id());
2534 return;
2535 }
2536 address low_addr = stack_end();
2537 size_t len = stack_guard_zone_size();
2538
2539 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2540 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2541
2542 int must_commit = os::must_commit_stack_guard_pages();
2543 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2544
2545 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2546 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2547 return;
2548 }
2549
2550 if (os::guard_memory((char *) low_addr, len)) {
2551 _stack_guard_state = stack_guard_enabled;
2552 } else {
2553 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2554 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2555 if (os::uncommit_memory((char *) low_addr, len)) {
2556 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2557 }
2558 return;
2559 }
2560
2561 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2562 PTR_FORMAT "-" PTR_FORMAT ".",
2563 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2564 }
2565
2566 void JavaThread::remove_stack_guard_pages() {
2567 assert(Thread::current() == this, "from different thread");
2568 if (_stack_guard_state == stack_guard_unused) return;
2569 address low_addr = stack_end();
2570 size_t len = stack_guard_zone_size();
2571
2572 if (os::must_commit_stack_guard_pages()) {
2573 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2574 _stack_guard_state = stack_guard_unused;
2575 } else {
2576 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2577 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2578 return;
2579 }
2580 } else {
2581 if (_stack_guard_state == stack_guard_unused) return;
2582 if (os::unguard_memory((char *) low_addr, len)) {
2583 _stack_guard_state = stack_guard_unused;
2584 } else {
2585 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2586 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2587 return;
2588 }
2589 }
2590
2591 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2592 PTR_FORMAT "-" PTR_FORMAT ".",
2593 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2594 }
2595
2596 void JavaThread::enable_stack_reserved_zone() {
2597 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2598 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2599
2600 // The base notation is from the stack's point of view, growing downward.
2601 // We need to adjust it to work correctly with guard_memory()
2602 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2603
2604 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2605 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2606
2607 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2608 _stack_guard_state = stack_guard_enabled;
2609 } else {
2610 warning("Attempt to guard stack reserved zone failed.");
2611 }
2612 enable_register_stack_guard();
2613 }
2614
2615 void JavaThread::disable_stack_reserved_zone() {
2616 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2617 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2618
2619 // Simply return if called for a thread that does not use guard pages.
2620 if (_stack_guard_state == stack_guard_unused) return;
2621
2622 // The base notation is from the stack's point of view, growing downward.
2623 // We need to adjust it to work correctly with guard_memory()
2624 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2625
2626 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2627 _stack_guard_state = stack_guard_reserved_disabled;
2628 } else {
2629 warning("Attempt to unguard stack reserved zone failed.");
2630 }
2631 disable_register_stack_guard();
2632 }
2633
2634 void JavaThread::enable_stack_yellow_reserved_zone() {
2635 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2636 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2637
2638 // The base notation is from the stacks point of view, growing downward.
2639 // We need to adjust it to work correctly with guard_memory()
2640 address base = stack_red_zone_base();
2641
2642 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2643 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2644
2645 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2646 _stack_guard_state = stack_guard_enabled;
2647 } else {
2648 warning("Attempt to guard stack yellow zone failed.");
2649 }
2650 enable_register_stack_guard();
2651 }
2652
2653 void JavaThread::disable_stack_yellow_reserved_zone() {
2654 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2655 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2656
2657 // Simply return if called for a thread that does not use guard pages.
2658 if (_stack_guard_state == stack_guard_unused) return;
2659
2660 // The base notation is from the stacks point of view, growing downward.
2661 // We need to adjust it to work correctly with guard_memory()
2662 address base = stack_red_zone_base();
2663
2664 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2665 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2666 } else {
2667 warning("Attempt to unguard stack yellow zone failed.");
2668 }
2669 disable_register_stack_guard();
2670 }
2671
2672 void JavaThread::enable_stack_red_zone() {
2673 // The base notation is from the stacks point of view, growing downward.
2674 // We need to adjust it to work correctly with guard_memory()
2675 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2676 address base = stack_red_zone_base() - stack_red_zone_size();
2677
2678 guarantee(base < stack_base(), "Error calculating stack red zone");
2679 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2680
2681 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2682 warning("Attempt to guard stack red zone failed.");
2683 }
2684 }
2685
2686 void JavaThread::disable_stack_red_zone() {
2687 // The base notation is from the stacks point of view, growing downward.
2688 // We need to adjust it to work correctly with guard_memory()
2689 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2690 address base = stack_red_zone_base() - stack_red_zone_size();
2691 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2692 warning("Attempt to unguard stack red zone failed.");
2693 }
2694 }
2695
2696 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2697 // ignore is there is no stack
2698 if (!has_last_Java_frame()) return;
2699 // traverse the stack frames. Starts from top frame.
2700 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2701 frame* fr = fst.current();
2702 f(fr, fst.register_map());
2703 }
2704 }
2705
2706
2707 #ifndef PRODUCT
2708 // Deoptimization
2709 // Function for testing deoptimization
2710 void JavaThread::deoptimize() {
2711 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2712 StackFrameStream fst(this, UseBiasedLocking);
2713 bool deopt = false; // Dump stack only if a deopt actually happens.
2714 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2715 // Iterate over all frames in the thread and deoptimize
2716 for (; !fst.is_done(); fst.next()) {
2717 if (fst.current()->can_be_deoptimized()) {
2718
2719 if (only_at) {
2720 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2721 // consists of comma or carriage return separated numbers so
2722 // search for the current bci in that string.
2723 address pc = fst.current()->pc();
2724 nmethod* nm = (nmethod*) fst.current()->cb();
2725 ScopeDesc* sd = nm->scope_desc_at(pc);
2726 char buffer[8];
2727 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2728 size_t len = strlen(buffer);
2729 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2730 while (found != NULL) {
2731 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2732 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2733 // Check that the bci found is bracketed by terminators.
2734 break;
2735 }
2736 found = strstr(found + 1, buffer);
2737 }
2738 if (!found) {
2739 continue;
2740 }
2741 }
2742
2743 if (DebugDeoptimization && !deopt) {
2744 deopt = true; // One-time only print before deopt
2745 tty->print_cr("[BEFORE Deoptimization]");
2746 trace_frames();
2747 trace_stack();
2748 }
2749 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2750 }
2751 }
2752
2753 if (DebugDeoptimization && deopt) {
2754 tty->print_cr("[AFTER Deoptimization]");
2755 trace_frames();
2756 }
2757 }
2758
2759
2760 // Make zombies
2761 void JavaThread::make_zombies() {
2762 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2763 if (fst.current()->can_be_deoptimized()) {
2764 // it is a Java nmethod
2765 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2766 nm->make_not_entrant();
2767 }
2768 }
2769 }
2770 #endif // PRODUCT
2771
2772
2773 void JavaThread::deoptimized_wrt_marked_nmethods() {
2774 if (!has_last_Java_frame()) return;
2775 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2776 StackFrameStream fst(this, UseBiasedLocking);
2777 for (; !fst.is_done(); fst.next()) {
2778 if (fst.current()->should_be_deoptimized()) {
2779 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2780 }
2781 }
2782 }
2783
2784
2785 // If the caller is a NamedThread, then remember, in the current scope,
2786 // the given JavaThread in its _processed_thread field.
2787 class RememberProcessedThread: public StackObj {
2788 NamedThread* _cur_thr;
2789 public:
2790 RememberProcessedThread(JavaThread* jthr) {
2791 Thread* thread = Thread::current();
2792 if (thread->is_Named_thread()) {
2793 _cur_thr = (NamedThread *)thread;
2794 _cur_thr->set_processed_thread(jthr);
2795 } else {
2796 _cur_thr = NULL;
2797 }
2798 }
2799
2800 ~RememberProcessedThread() {
2801 if (_cur_thr) {
2802 _cur_thr->set_processed_thread(NULL);
2803 }
2804 }
2805 };
2806
2807 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2808 // Verify that the deferred card marks have been flushed.
2809 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2810
2811 // Traverse the GCHandles
2812 Thread::oops_do(f, cf);
2813
2814 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2815 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2816
2817 if (has_last_Java_frame()) {
2818 // Record JavaThread to GC thread
2819 RememberProcessedThread rpt(this);
2820
2821 // Traverse the privileged stack
2822 if (_privileged_stack_top != NULL) {
2823 _privileged_stack_top->oops_do(f);
2824 }
2825
2826 // traverse the registered growable array
2827 if (_array_for_gc != NULL) {
2828 for (int index = 0; index < _array_for_gc->length(); index++) {
2829 f->do_oop(_array_for_gc->adr_at(index));
2830 }
2831 }
2832
2833 // Traverse the monitor chunks
2834 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2835 chunk->oops_do(f);
2836 }
2837
2838 // Traverse the execution stack
2839 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2840 fst.current()->oops_do(f, cf, fst.register_map());
2841 }
2842 }
2843
2844 // callee_target is never live across a gc point so NULL it here should
2845 // it still contain a methdOop.
2846
2847 set_callee_target(NULL);
2848
2849 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2850 // If we have deferred set_locals there might be oops waiting to be
2851 // written
2852 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2853 if (list != NULL) {
2854 for (int i = 0; i < list->length(); i++) {
2855 list->at(i)->oops_do(f);
2856 }
2857 }
2858
2859 // Traverse instance variables at the end since the GC may be moving things
2860 // around using this function
2861 f->do_oop((oop*) &_threadObj);
2862 f->do_oop((oop*) &_vm_result);
2863 f->do_oop((oop*) &_exception_oop);
2864 f->do_oop((oop*) &_pending_async_exception);
2865
2866 if (jvmti_thread_state() != NULL) {
2867 jvmti_thread_state()->oops_do(f);
2868 }
2869 }
2870
2871 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2872 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2873 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2874
2875 if (has_last_Java_frame()) {
2876 // Traverse the execution stack
2877 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2878 fst.current()->nmethods_do(cf);
2879 }
2880 }
2881 }
2882
2883 void JavaThread::metadata_do(void f(Metadata*)) {
2884 if (has_last_Java_frame()) {
2885 // Traverse the execution stack to call f() on the methods in the stack
2886 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2887 fst.current()->metadata_do(f);
2888 }
2889 } else if (is_Compiler_thread()) {
2890 // need to walk ciMetadata in current compile tasks to keep alive.
2891 CompilerThread* ct = (CompilerThread*)this;
2892 if (ct->env() != NULL) {
2893 ct->env()->metadata_do(f);
2894 }
2895 CompileTask* task = ct->task();
2896 if (task != NULL) {
2897 task->metadata_do(f);
2898 }
2899 }
2900 }
2901
2902 // Printing
2903 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2904 switch (_thread_state) {
2905 case _thread_uninitialized: return "_thread_uninitialized";
2906 case _thread_new: return "_thread_new";
2907 case _thread_new_trans: return "_thread_new_trans";
2908 case _thread_in_native: return "_thread_in_native";
2909 case _thread_in_native_trans: return "_thread_in_native_trans";
2910 case _thread_in_vm: return "_thread_in_vm";
2911 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2912 case _thread_in_Java: return "_thread_in_Java";
2913 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2914 case _thread_blocked: return "_thread_blocked";
2915 case _thread_blocked_trans: return "_thread_blocked_trans";
2916 default: return "unknown thread state";
2917 }
2918 }
2919
2920 #ifndef PRODUCT
2921 void JavaThread::print_thread_state_on(outputStream *st) const {
2922 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2923 };
2924 void JavaThread::print_thread_state() const {
2925 print_thread_state_on(tty);
2926 }
2927 #endif // PRODUCT
2928
2929 // Called by Threads::print() for VM_PrintThreads operation
2930 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2931 st->print_raw("\"");
2932 st->print_raw(get_thread_name());
2933 st->print_raw("\" ");
2934 oop thread_oop = threadObj();
2935 if (thread_oop != NULL) {
2936 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2937 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2938 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2939 }
2940 Thread::print_on(st, print_extended_info);
2941 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2942 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2943 if (thread_oop != NULL) {
2944 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2945 }
2946 #ifndef PRODUCT
2947 print_thread_state_on(st);
2948 _safepoint_state->print_on(st);
2949 #endif // PRODUCT
2950 if (is_Compiler_thread()) {
2951 CompileTask *task = ((CompilerThread*)this)->task();
2952 if (task != NULL) {
2953 st->print(" Compiling: ");
2954 task->print(st, NULL, true, false);
2955 } else {
2956 st->print(" No compile task");
2957 }
2958 st->cr();
2959 }
2960 }
2961
2962 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2963 st->print("%s", get_thread_name_string(buf, buflen));
2964 }
2965
2966 // Called by fatal error handler. The difference between this and
2967 // JavaThread::print() is that we can't grab lock or allocate memory.
2968 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2969 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2970 oop thread_obj = threadObj();
2971 if (thread_obj != NULL) {
2972 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2973 }
2974 st->print(" [");
2975 st->print("%s", _get_thread_state_name(_thread_state));
2976 if (osthread()) {
2977 st->print(", id=%d", osthread()->thread_id());
2978 }
2979 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2980 p2i(stack_end()), p2i(stack_base()));
2981 st->print("]");
2982
2983 ThreadsSMRSupport::print_info_on(this, st);
2984 return;
2985 }
2986
2987 // Verification
2988
2989 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2990
2991 void JavaThread::verify() {
2992 // Verify oops in the thread.
2993 oops_do(&VerifyOopClosure::verify_oop, NULL);
2994
2995 // Verify the stack frames.
2996 frames_do(frame_verify);
2997 }
2998
2999 // CR 6300358 (sub-CR 2137150)
3000 // Most callers of this method assume that it can't return NULL but a
3001 // thread may not have a name whilst it is in the process of attaching to
3002 // the VM - see CR 6412693, and there are places where a JavaThread can be
3003 // seen prior to having it's threadObj set (eg JNI attaching threads and
3004 // if vm exit occurs during initialization). These cases can all be accounted
3005 // for such that this method never returns NULL.
3006 const char* JavaThread::get_thread_name() const {
3007 #ifdef ASSERT
3008 // early safepoints can hit while current thread does not yet have TLS
3009 if (!SafepointSynchronize::is_at_safepoint()) {
3010 Thread *cur = Thread::current();
3011 if (!(cur->is_Java_thread() && cur == this)) {
3012 // Current JavaThreads are allowed to get their own name without
3013 // the Threads_lock.
3014 assert_locked_or_safepoint(Threads_lock);
3015 }
3016 }
3017 #endif // ASSERT
3018 return get_thread_name_string();
3019 }
3020
3021 // Returns a non-NULL representation of this thread's name, or a suitable
3022 // descriptive string if there is no set name
3023 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3024 const char* name_str;
3025 oop thread_obj = threadObj();
3026 if (thread_obj != NULL) {
3027 oop name = java_lang_Thread::name(thread_obj);
3028 if (name != NULL) {
3029 if (buf == NULL) {
3030 name_str = java_lang_String::as_utf8_string(name);
3031 } else {
3032 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3033 }
3034 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3035 name_str = "<no-name - thread is attaching>";
3036 } else {
3037 name_str = Thread::name();
3038 }
3039 } else {
3040 name_str = Thread::name();
3041 }
3042 assert(name_str != NULL, "unexpected NULL thread name");
3043 return name_str;
3044 }
3045
3046
3047 const char* JavaThread::get_threadgroup_name() const {
3048 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3049 oop thread_obj = threadObj();
3050 if (thread_obj != NULL) {
3051 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3052 if (thread_group != NULL) {
3053 // ThreadGroup.name can be null
3054 return java_lang_ThreadGroup::name(thread_group);
3055 }
3056 }
3057 return NULL;
3058 }
3059
3060 const char* JavaThread::get_parent_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 oop parent = java_lang_ThreadGroup::parent(thread_group);
3067 if (parent != NULL) {
3068 // ThreadGroup.name can be null
3069 return java_lang_ThreadGroup::name(parent);
3070 }
3071 }
3072 }
3073 return NULL;
3074 }
3075
3076 ThreadPriority JavaThread::java_priority() const {
3077 oop thr_oop = threadObj();
3078 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3079 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3080 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3081 return priority;
3082 }
3083
3084 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3085
3086 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3087 // Link Java Thread object <-> C++ Thread
3088
3089 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3090 // and put it into a new Handle. The Handle "thread_oop" can then
3091 // be used to pass the C++ thread object to other methods.
3092
3093 // Set the Java level thread object (jthread) field of the
3094 // new thread (a JavaThread *) to C++ thread object using the
3095 // "thread_oop" handle.
3096
3097 // Set the thread field (a JavaThread *) of the
3098 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3099
3100 Handle thread_oop(Thread::current(),
3101 JNIHandles::resolve_non_null(jni_thread));
3102 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3103 "must be initialized");
3104 set_threadObj(thread_oop());
3105 java_lang_Thread::set_thread(thread_oop(), this);
3106
3107 if (prio == NoPriority) {
3108 prio = java_lang_Thread::priority(thread_oop());
3109 assert(prio != NoPriority, "A valid priority should be present");
3110 }
3111
3112 // Push the Java priority down to the native thread; needs Threads_lock
3113 Thread::set_priority(this, prio);
3114
3115 // Add the new thread to the Threads list and set it in motion.
3116 // We must have threads lock in order to call Threads::add.
3117 // It is crucial that we do not block before the thread is
3118 // added to the Threads list for if a GC happens, then the java_thread oop
3119 // will not be visited by GC.
3120 Threads::add(this);
3121 }
3122
3123 oop JavaThread::current_park_blocker() {
3124 // Support for JSR-166 locks
3125 oop thread_oop = threadObj();
3126 if (thread_oop != NULL &&
3127 JDK_Version::current().supports_thread_park_blocker()) {
3128 return java_lang_Thread::park_blocker(thread_oop);
3129 }
3130 return NULL;
3131 }
3132
3133
3134 void JavaThread::print_stack_on(outputStream* st) {
3135 if (!has_last_Java_frame()) return;
3136 ResourceMark rm;
3137 HandleMark hm;
3138
3139 RegisterMap reg_map(this);
3140 vframe* start_vf = last_java_vframe(®_map);
3141 int count = 0;
3142 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3143 if (f->is_java_frame()) {
3144 javaVFrame* jvf = javaVFrame::cast(f);
3145 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3146
3147 // Print out lock information
3148 if (JavaMonitorsInStackTrace) {
3149 jvf->print_lock_info_on(st, count);
3150 }
3151 } else {
3152 // Ignore non-Java frames
3153 }
3154
3155 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3156 count++;
3157 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3158 }
3159 }
3160
3161
3162 // JVMTI PopFrame support
3163 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3164 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3165 if (in_bytes(size_in_bytes) != 0) {
3166 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3167 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3168 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3169 }
3170 }
3171
3172 void* JavaThread::popframe_preserved_args() {
3173 return _popframe_preserved_args;
3174 }
3175
3176 ByteSize JavaThread::popframe_preserved_args_size() {
3177 return in_ByteSize(_popframe_preserved_args_size);
3178 }
3179
3180 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3181 int sz = in_bytes(popframe_preserved_args_size());
3182 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3183 return in_WordSize(sz / wordSize);
3184 }
3185
3186 void JavaThread::popframe_free_preserved_args() {
3187 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3188 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3189 _popframe_preserved_args = NULL;
3190 _popframe_preserved_args_size = 0;
3191 }
3192
3193 #ifndef PRODUCT
3194
3195 void JavaThread::trace_frames() {
3196 tty->print_cr("[Describe stack]");
3197 int frame_no = 1;
3198 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3199 tty->print(" %d. ", frame_no++);
3200 fst.current()->print_value_on(tty, this);
3201 tty->cr();
3202 }
3203 }
3204
3205 class PrintAndVerifyOopClosure: public OopClosure {
3206 protected:
3207 template <class T> inline void do_oop_work(T* p) {
3208 oop obj = RawAccess<>::oop_load(p);
3209 if (obj == NULL) return;
3210 tty->print(INTPTR_FORMAT ": ", p2i(p));
3211 if (oopDesc::is_oop_or_null(obj)) {
3212 if (obj->is_objArray()) {
3213 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3214 } else {
3215 obj->print();
3216 }
3217 } else {
3218 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3219 }
3220 tty->cr();
3221 }
3222 public:
3223 virtual void do_oop(oop* p) { do_oop_work(p); }
3224 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3225 };
3226
3227
3228 static void oops_print(frame* f, const RegisterMap *map) {
3229 PrintAndVerifyOopClosure print;
3230 f->print_value();
3231 f->oops_do(&print, NULL, (RegisterMap*)map);
3232 }
3233
3234 // Print our all the locations that contain oops and whether they are
3235 // valid or not. This useful when trying to find the oldest frame
3236 // where an oop has gone bad since the frame walk is from youngest to
3237 // oldest.
3238 void JavaThread::trace_oops() {
3239 tty->print_cr("[Trace oops]");
3240 frames_do(oops_print);
3241 }
3242
3243
3244 #ifdef ASSERT
3245 // Print or validate the layout of stack frames
3246 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3247 ResourceMark rm;
3248 PRESERVE_EXCEPTION_MARK;
3249 FrameValues values;
3250 int frame_no = 0;
3251 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3252 fst.current()->describe(values, ++frame_no);
3253 if (depth == frame_no) break;
3254 }
3255 if (validate_only) {
3256 values.validate();
3257 } else {
3258 tty->print_cr("[Describe stack layout]");
3259 values.print(this);
3260 }
3261 }
3262 #endif
3263
3264 void JavaThread::trace_stack_from(vframe* start_vf) {
3265 ResourceMark rm;
3266 int vframe_no = 1;
3267 for (vframe* f = start_vf; f; f = f->sender()) {
3268 if (f->is_java_frame()) {
3269 javaVFrame::cast(f)->print_activation(vframe_no++);
3270 } else {
3271 f->print();
3272 }
3273 if (vframe_no > StackPrintLimit) {
3274 tty->print_cr("...<more frames>...");
3275 return;
3276 }
3277 }
3278 }
3279
3280
3281 void JavaThread::trace_stack() {
3282 if (!has_last_Java_frame()) return;
3283 ResourceMark rm;
3284 HandleMark hm;
3285 RegisterMap reg_map(this);
3286 trace_stack_from(last_java_vframe(®_map));
3287 }
3288
3289
3290 #endif // PRODUCT
3291
3292
3293 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3294 assert(reg_map != NULL, "a map must be given");
3295 frame f = last_frame();
3296 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3297 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3298 }
3299 return NULL;
3300 }
3301
3302
3303 Klass* JavaThread::security_get_caller_class(int depth) {
3304 vframeStream vfst(this);
3305 vfst.security_get_caller_frame(depth);
3306 if (!vfst.at_end()) {
3307 return vfst.method()->method_holder();
3308 }
3309 return NULL;
3310 }
3311
3312 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3313 assert(thread->is_Compiler_thread(), "must be compiler thread");
3314 CompileBroker::compiler_thread_loop();
3315 }
3316
3317 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3318 NMethodSweeper::sweeper_loop();
3319 }
3320
3321 // Create a CompilerThread
3322 CompilerThread::CompilerThread(CompileQueue* queue,
3323 CompilerCounters* counters)
3324 : JavaThread(&compiler_thread_entry) {
3325 _env = NULL;
3326 _log = NULL;
3327 _task = NULL;
3328 _queue = queue;
3329 _counters = counters;
3330 _buffer_blob = NULL;
3331 _compiler = NULL;
3332
3333 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3334 resource_area()->bias_to(mtCompiler);
3335
3336 #ifndef PRODUCT
3337 _ideal_graph_printer = NULL;
3338 #endif
3339 }
3340
3341 CompilerThread::~CompilerThread() {
3342 // Delete objects which were allocated on heap.
3343 delete _counters;
3344 }
3345
3346 bool CompilerThread::can_call_java() const {
3347 return _compiler != NULL && _compiler->is_jvmci();
3348 }
3349
3350 // Create sweeper thread
3351 CodeCacheSweeperThread::CodeCacheSweeperThread()
3352 : JavaThread(&sweeper_thread_entry) {
3353 _scanned_compiled_method = NULL;
3354 }
3355
3356 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3357 JavaThread::oops_do(f, cf);
3358 if (_scanned_compiled_method != NULL && cf != NULL) {
3359 // Safepoints can occur when the sweeper is scanning an nmethod so
3360 // process it here to make sure it isn't unloaded in the middle of
3361 // a scan.
3362 cf->do_code_blob(_scanned_compiled_method);
3363 }
3364 }
3365
3366 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3367 JavaThread::nmethods_do(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
3377 // ======= Threads ========
3378
3379 // The Threads class links together all active threads, and provides
3380 // operations over all threads. It is protected by the Threads_lock,
3381 // which is also used in other global contexts like safepointing.
3382 // ThreadsListHandles are used to safely perform operations on one
3383 // or more threads without the risk of the thread exiting during the
3384 // operation.
3385 //
3386 // Note: The Threads_lock is currently more widely used than we
3387 // would like. We are actively migrating Threads_lock uses to other
3388 // mechanisms in order to reduce Threads_lock contention.
3389
3390 JavaThread* Threads::_thread_list = NULL;
3391 int Threads::_number_of_threads = 0;
3392 int Threads::_number_of_non_daemon_threads = 0;
3393 int Threads::_return_code = 0;
3394 int Threads::_thread_claim_parity = 0;
3395 size_t JavaThread::_stack_size_at_create = 0;
3396
3397 #ifdef ASSERT
3398 bool Threads::_vm_complete = false;
3399 size_t Threads::_threads_before_barrier_set = 0;
3400 #endif
3401
3402 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3403 Prefetch::read((void*)addr, prefetch_interval);
3404 return *addr;
3405 }
3406
3407 // Possibly the ugliest for loop the world has seen. C++ does not allow
3408 // multiple types in the declaration section of the for loop. In this case
3409 // we are only dealing with pointers and hence can cast them. It looks ugly
3410 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3411 #define DO_JAVA_THREADS(LIST, X) \
3412 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3413 *MACRO_list = (JavaThread*)(LIST), \
3414 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3415 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3416 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3417 MACRO_current_p != MACRO_end; \
3418 MACRO_current_p++, \
3419 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3420
3421 // All JavaThreads
3422 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3423
3424 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3425 void Threads::non_java_threads_do(ThreadClosure* tc) {
3426 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3427 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3428 tc->do_thread(njti.current());
3429 }
3430 }
3431
3432 // All JavaThreads
3433 void Threads::java_threads_do(ThreadClosure* tc) {
3434 assert_locked_or_safepoint(Threads_lock);
3435 // ALL_JAVA_THREADS iterates through all JavaThreads.
3436 ALL_JAVA_THREADS(p) {
3437 tc->do_thread(p);
3438 }
3439 }
3440
3441 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3442 assert_locked_or_safepoint(Threads_lock);
3443 java_threads_do(tc);
3444 tc->do_thread(VMThread::vm_thread());
3445 }
3446
3447 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3448 void Threads::threads_do(ThreadClosure* tc) {
3449 assert_locked_or_safepoint(Threads_lock);
3450 java_threads_do(tc);
3451 non_java_threads_do(tc);
3452 }
3453
3454 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3455 int cp = Threads::thread_claim_parity();
3456 ALL_JAVA_THREADS(p) {
3457 if (p->claim_oops_do(is_par, cp)) {
3458 tc->do_thread(p);
3459 }
3460 }
3461 VMThread* vmt = VMThread::vm_thread();
3462 if (vmt->claim_oops_do(is_par, cp)) {
3463 tc->do_thread(vmt);
3464 }
3465 }
3466
3467 // The system initialization in the library has three phases.
3468 //
3469 // Phase 1: java.lang.System class initialization
3470 // java.lang.System is a primordial class loaded and initialized
3471 // by the VM early during startup. java.lang.System.<clinit>
3472 // only does registerNatives and keeps the rest of the class
3473 // initialization work later until thread initialization completes.
3474 //
3475 // System.initPhase1 initializes the system properties, the static
3476 // fields in, out, and err. Set up java signal handlers, OS-specific
3477 // system settings, and thread group of the main thread.
3478 static void call_initPhase1(TRAPS) {
3479 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3480 JavaValue result(T_VOID);
3481 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3482 vmSymbols::void_method_signature(), CHECK);
3483 }
3484
3485 // Phase 2. Module system initialization
3486 // This will initialize the module system. Only java.base classes
3487 // can be loaded until phase 2 completes.
3488 //
3489 // Call System.initPhase2 after the compiler initialization and jsr292
3490 // classes get initialized because module initialization runs a lot of java
3491 // code, that for performance reasons, should be compiled. Also, this will
3492 // enable the startup code to use lambda and other language features in this
3493 // phase and onward.
3494 //
3495 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3496 static void call_initPhase2(TRAPS) {
3497 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3498
3499 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3500
3501 JavaValue result(T_INT);
3502 JavaCallArguments args;
3503 args.push_int(DisplayVMOutputToStderr);
3504 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3505 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3506 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3507 if (result.get_jint() != JNI_OK) {
3508 vm_exit_during_initialization(); // no message or exception
3509 }
3510
3511 universe_post_module_init();
3512 }
3513
3514 // Phase 3. final setup - set security manager, system class loader and TCCL
3515 //
3516 // This will instantiate and set the security manager, set the system class
3517 // loader as well as the thread context class loader. The security manager
3518 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3519 // other modules or the application's classpath.
3520 static void call_initPhase3(TRAPS) {
3521 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3522 JavaValue result(T_VOID);
3523 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3524 vmSymbols::void_method_signature(), CHECK);
3525 }
3526
3527 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3528 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3529
3530 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3531 create_vm_init_libraries();
3532 }
3533
3534 initialize_class(vmSymbols::java_lang_String(), CHECK);
3535
3536 // Inject CompactStrings value after the static initializers for String ran.
3537 java_lang_String::set_compact_strings(CompactStrings);
3538
3539 // Initialize java_lang.System (needed before creating the thread)
3540 initialize_class(vmSymbols::java_lang_System(), CHECK);
3541 // The VM creates & returns objects of this class. Make sure it's initialized.
3542 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3543 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3544 Handle thread_group = create_initial_thread_group(CHECK);
3545 Universe::set_main_thread_group(thread_group());
3546 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3547 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3548 main_thread->set_threadObj(thread_object);
3549 // Set thread status to running since main thread has
3550 // been started and running.
3551 java_lang_Thread::set_thread_status(thread_object,
3552 java_lang_Thread::RUNNABLE);
3553
3554 // The VM creates objects of this class.
3555 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3556
3557 // The VM preresolves methods to these classes. Make sure that they get initialized
3558 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3559 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3560
3561 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3562 call_initPhase1(CHECK);
3563
3564 // get the Java runtime name after java.lang.System is initialized
3565 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3566 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3567
3568 // an instance of OutOfMemory exception has been allocated earlier
3569 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3570 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3571 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3572 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3573 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3574 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3575 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3576 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3577 }
3578
3579 void Threads::initialize_jsr292_core_classes(TRAPS) {
3580 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3581
3582 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3583 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3584 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3585 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3586 }
3587
3588 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3589 extern void JDK_Version_init();
3590
3591 // Preinitialize version info.
3592 VM_Version::early_initialize();
3593
3594 // Check version
3595 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3596
3597 // Initialize library-based TLS
3598 ThreadLocalStorage::init();
3599
3600 // Initialize the output stream module
3601 ostream_init();
3602
3603 // Process java launcher properties.
3604 Arguments::process_sun_java_launcher_properties(args);
3605
3606 // Initialize the os module
3607 os::init();
3608
3609 // Record VM creation timing statistics
3610 TraceVmCreationTime create_vm_timer;
3611 create_vm_timer.start();
3612
3613 // Initialize system properties.
3614 Arguments::init_system_properties();
3615
3616 // So that JDK version can be used as a discriminator when parsing arguments
3617 JDK_Version_init();
3618
3619 // Update/Initialize System properties after JDK version number is known
3620 Arguments::init_version_specific_system_properties();
3621
3622 // Make sure to initialize log configuration *before* parsing arguments
3623 LogConfiguration::initialize(create_vm_timer.begin_time());
3624
3625 // Parse arguments
3626 // Note: this internally calls os::init_container_support()
3627 jint parse_result = Arguments::parse(args);
3628 if (parse_result != JNI_OK) return parse_result;
3629
3630 os::init_before_ergo();
3631
3632 jint ergo_result = Arguments::apply_ergo();
3633 if (ergo_result != JNI_OK) return ergo_result;
3634
3635 // Final check of all ranges after ergonomics which may change values.
3636 if (!JVMFlagRangeList::check_ranges()) {
3637 return JNI_EINVAL;
3638 }
3639
3640 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3641 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3642 if (!constraint_result) {
3643 return JNI_EINVAL;
3644 }
3645
3646 JVMFlagWriteableList::mark_startup();
3647
3648 if (PauseAtStartup) {
3649 os::pause();
3650 }
3651
3652 HOTSPOT_VM_INIT_BEGIN();
3653
3654 // Timing (must come after argument parsing)
3655 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3656
3657 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3658 // Initialize assert poison page mechanism.
3659 if (ShowRegistersOnAssert) {
3660 initialize_assert_poison();
3661 }
3662 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3663
3664 // Initialize the os module after parsing the args
3665 jint os_init_2_result = os::init_2();
3666 if (os_init_2_result != JNI_OK) return os_init_2_result;
3667
3668 SafepointMechanism::initialize();
3669
3670 jint adjust_after_os_result = Arguments::adjust_after_os();
3671 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3672
3673 // Initialize output stream logging
3674 ostream_init_log();
3675
3676 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3677 // Must be before create_vm_init_agents()
3678 if (Arguments::init_libraries_at_startup()) {
3679 convert_vm_init_libraries_to_agents();
3680 }
3681
3682 // Launch -agentlib/-agentpath and converted -Xrun agents
3683 if (Arguments::init_agents_at_startup()) {
3684 create_vm_init_agents();
3685 }
3686
3687 // Initialize Threads state
3688 _thread_list = NULL;
3689 _number_of_threads = 0;
3690 _number_of_non_daemon_threads = 0;
3691
3692 // Initialize global data structures and create system classes in heap
3693 vm_init_globals();
3694
3695 #if INCLUDE_JVMCI
3696 if (JVMCICounterSize > 0) {
3697 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3698 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3699 } else {
3700 JavaThread::_jvmci_old_thread_counters = NULL;
3701 }
3702 #endif // INCLUDE_JVMCI
3703
3704 // Attach the main thread to this os thread
3705 JavaThread* main_thread = new JavaThread();
3706 main_thread->set_thread_state(_thread_in_vm);
3707 main_thread->initialize_thread_current();
3708 // must do this before set_active_handles
3709 main_thread->record_stack_base_and_size();
3710 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3711
3712 if (!main_thread->set_as_starting_thread()) {
3713 vm_shutdown_during_initialization(
3714 "Failed necessary internal allocation. Out of swap space");
3715 main_thread->smr_delete();
3716 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3717 return JNI_ENOMEM;
3718 }
3719
3720 // Enable guard page *after* os::create_main_thread(), otherwise it would
3721 // crash Linux VM, see notes in os_linux.cpp.
3722 main_thread->create_stack_guard_pages();
3723
3724 // Initialize Java-Level synchronization subsystem
3725 ObjectMonitor::Initialize();
3726
3727 // Initialize global modules
3728 jint status = init_globals();
3729 if (status != JNI_OK) {
3730 main_thread->smr_delete();
3731 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3732 return status;
3733 }
3734
3735 JFR_ONLY(Jfr::on_vm_init();)
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 // We need this to update the java.vm.info property in case any flags used
3780 // to initially define it have been changed. This is needed for both CDS and
3781 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3782 // is initially computed. See Abstract_VM_Version::vm_info_string().
3783 // This update must happen before we initialize the java classes, but
3784 // after any initialization logic that might modify the flags.
3785 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3786
3787 Thread* THREAD = Thread::current();
3788
3789 // Always call even when there are not JVMTI environments yet, since environments
3790 // may be attached late and JVMTI must track phases of VM execution
3791 JvmtiExport::enter_early_start_phase();
3792
3793 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3794 JvmtiExport::post_early_vm_start();
3795
3796 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3797
3798 quicken_jni_functions();
3799
3800 // No more stub generation allowed after that point.
3801 StubCodeDesc::freeze();
3802
3803 // Set flag that basic initialization has completed. Used by exceptions and various
3804 // debug stuff, that does not work until all basic classes have been initialized.
3805 set_init_completed();
3806
3807 LogConfiguration::post_initialize();
3808 Metaspace::post_initialize();
3809
3810 HOTSPOT_VM_INIT_END();
3811
3812 // record VM initialization completion time
3813 #if INCLUDE_MANAGEMENT
3814 Management::record_vm_init_completed();
3815 #endif // INCLUDE_MANAGEMENT
3816
3817 // Signal Dispatcher needs to be started before VMInit event is posted
3818 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3819
3820 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3821 if (!DisableAttachMechanism) {
3822 AttachListener::vm_start();
3823 if (StartAttachListener || AttachListener::init_at_startup()) {
3824 AttachListener::init();
3825 }
3826 }
3827
3828 // Launch -Xrun agents
3829 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3830 // back-end can launch with -Xdebug -Xrunjdwp.
3831 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3832 create_vm_init_libraries();
3833 }
3834
3835 if (CleanChunkPoolAsync) {
3836 Chunk::start_chunk_pool_cleaner_task();
3837 }
3838
3839 // initialize compiler(s)
3840 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3841 #if INCLUDE_JVMCI
3842 bool force_JVMCI_intialization = false;
3843 if (EnableJVMCI) {
3844 // Initialize JVMCI eagerly when it is explicitly requested.
3845 // Or when JVMCIPrintProperties is enabled.
3846 // The JVMCI Java initialization code will read this flag and
3847 // do the printing if it's set.
3848 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3849
3850 if (!force_JVMCI_intialization) {
3851 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3852 // compilations via JVMCI will not actually block until JVMCI is initialized.
3853 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3854 }
3855 }
3856 #endif
3857 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3858 // Postpone completion of compiler initialization to after JVMCI
3859 // is initialized to avoid timeouts of blocking compilations.
3860 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3861 CompileBroker::compilation_init_phase2();
3862 }
3863 #endif
3864
3865 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3866 // It is done after compilers are initialized, because otherwise compilations of
3867 // signature polymorphic MH intrinsics can be missed
3868 // (see SystemDictionary::find_method_handle_intrinsic).
3869 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3870
3871 // This will initialize the module system. Only java.base classes can be
3872 // loaded until phase 2 completes
3873 call_initPhase2(CHECK_JNI_ERR);
3874
3875 // Always call even when there are not JVMTI environments yet, since environments
3876 // may be attached late and JVMTI must track phases of VM execution
3877 JvmtiExport::enter_start_phase();
3878
3879 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3880 JvmtiExport::post_vm_start();
3881
3882 // Final system initialization including security manager and system class loader
3883 call_initPhase3(CHECK_JNI_ERR);
3884
3885 // cache the system and platform class loaders
3886 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3887
3888 #if INCLUDE_CDS
3889 if (DumpSharedSpaces) {
3890 // capture the module path info from the ModuleEntryTable
3891 ClassLoader::initialize_module_path(THREAD);
3892 }
3893 #endif
3894
3895 #if INCLUDE_JVMCI
3896 if (force_JVMCI_intialization) {
3897 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3898 CompileBroker::compilation_init_phase2();
3899 }
3900 #endif
3901
3902 // Always call even when there are not JVMTI environments yet, since environments
3903 // may be attached late and JVMTI must track phases of VM execution
3904 JvmtiExport::enter_live_phase();
3905
3906 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3907 JvmtiExport::post_vm_initialized();
3908
3909 JFR_ONLY(Jfr::on_vm_start();)
3910
3911 #if INCLUDE_MANAGEMENT
3912 Management::initialize(THREAD);
3913
3914 if (HAS_PENDING_EXCEPTION) {
3915 // management agent fails to start possibly due to
3916 // configuration problem and is responsible for printing
3917 // stack trace if appropriate. Simply exit VM.
3918 vm_exit(1);
3919 }
3920 #endif // INCLUDE_MANAGEMENT
3921
3922 if (MemProfiling) MemProfiler::engage();
3923 StatSampler::engage();
3924 if (CheckJNICalls) JniPeriodicChecker::engage();
3925
3926 BiasedLocking::init();
3927
3928 #if INCLUDE_RTM_OPT
3929 RTMLockingCounters::init();
3930 #endif
3931
3932 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3933 call_postVMInitHook(THREAD);
3934 // The Java side of PostVMInitHook.run must deal with all
3935 // exceptions and provide means of diagnosis.
3936 if (HAS_PENDING_EXCEPTION) {
3937 CLEAR_PENDING_EXCEPTION;
3938 }
3939 }
3940
3941 {
3942 MutexLocker ml(PeriodicTask_lock);
3943 // Make sure the WatcherThread can be started by WatcherThread::start()
3944 // or by dynamic enrollment.
3945 WatcherThread::make_startable();
3946 // Start up the WatcherThread if there are any periodic tasks
3947 // NOTE: All PeriodicTasks should be registered by now. If they
3948 // aren't, late joiners might appear to start slowly (we might
3949 // take a while to process their first tick).
3950 if (PeriodicTask::num_tasks() > 0) {
3951 WatcherThread::start();
3952 }
3953 }
3954
3955 create_vm_timer.end();
3956 #ifdef ASSERT
3957 _vm_complete = true;
3958 #endif
3959
3960 if (DumpSharedSpaces) {
3961 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3962 ShouldNotReachHere();
3963 }
3964
3965 return JNI_OK;
3966 }
3967
3968 // type for the Agent_OnLoad and JVM_OnLoad entry points
3969 extern "C" {
3970 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3971 }
3972 // Find a command line agent library and return its entry point for
3973 // -agentlib: -agentpath: -Xrun
3974 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3975 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3976 const char *on_load_symbols[],
3977 size_t num_symbol_entries) {
3978 OnLoadEntry_t on_load_entry = NULL;
3979 void *library = NULL;
3980
3981 if (!agent->valid()) {
3982 char buffer[JVM_MAXPATHLEN];
3983 char ebuf[1024] = "";
3984 const char *name = agent->name();
3985 const char *msg = "Could not find agent library ";
3986
3987 // First check to see if agent is statically linked into executable
3988 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3989 library = agent->os_lib();
3990 } else if (agent->is_absolute_path()) {
3991 library = os::dll_load(name, ebuf, sizeof ebuf);
3992 if (library == NULL) {
3993 const char *sub_msg = " in absolute path, with error: ";
3994 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3995 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3996 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3997 // If we can't find the agent, exit.
3998 vm_exit_during_initialization(buf, NULL);
3999 FREE_C_HEAP_ARRAY(char, buf);
4000 }
4001 } else {
4002 // Try to load the agent from the standard dll directory
4003 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4004 name)) {
4005 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4006 }
4007 if (library == NULL) { // Try the library path directory.
4008 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4009 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4010 }
4011 if (library == NULL) {
4012 const char *sub_msg = " on the library path, with error: ";
4013 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4014
4015 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4016 strlen(ebuf) + strlen(sub_msg2) + 1;
4017 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4018 if (!agent->is_instrument_lib()) {
4019 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4020 } else {
4021 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4022 }
4023 // If we can't find the agent, exit.
4024 vm_exit_during_initialization(buf, NULL);
4025 FREE_C_HEAP_ARRAY(char, buf);
4026 }
4027 }
4028 }
4029 agent->set_os_lib(library);
4030 agent->set_valid();
4031 }
4032
4033 // Find the OnLoad function.
4034 on_load_entry =
4035 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4036 false,
4037 on_load_symbols,
4038 num_symbol_entries));
4039 return on_load_entry;
4040 }
4041
4042 // Find the JVM_OnLoad entry point
4043 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4044 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4045 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4046 }
4047
4048 // Find the Agent_OnLoad entry point
4049 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4050 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4051 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4052 }
4053
4054 // For backwards compatibility with -Xrun
4055 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4056 // treated like -agentpath:
4057 // Must be called before agent libraries are created
4058 void Threads::convert_vm_init_libraries_to_agents() {
4059 AgentLibrary* agent;
4060 AgentLibrary* next;
4061
4062 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4063 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4064 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4065
4066 // If there is an JVM_OnLoad function it will get called later,
4067 // otherwise see if there is an Agent_OnLoad
4068 if (on_load_entry == NULL) {
4069 on_load_entry = lookup_agent_on_load(agent);
4070 if (on_load_entry != NULL) {
4071 // switch it to the agent list -- so that Agent_OnLoad will be called,
4072 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4073 Arguments::convert_library_to_agent(agent);
4074 } else {
4075 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4076 }
4077 }
4078 }
4079 }
4080
4081 // Create agents for -agentlib: -agentpath: and converted -Xrun
4082 // Invokes Agent_OnLoad
4083 // Called very early -- before JavaThreads exist
4084 void Threads::create_vm_init_agents() {
4085 extern struct JavaVM_ main_vm;
4086 AgentLibrary* agent;
4087
4088 JvmtiExport::enter_onload_phase();
4089
4090 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4091 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4092
4093 if (on_load_entry != NULL) {
4094 // Invoke the Agent_OnLoad function
4095 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4096 if (err != JNI_OK) {
4097 vm_exit_during_initialization("agent library failed to init", agent->name());
4098 }
4099 } else {
4100 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4101 }
4102 }
4103 JvmtiExport::enter_primordial_phase();
4104 }
4105
4106 extern "C" {
4107 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4108 }
4109
4110 void Threads::shutdown_vm_agents() {
4111 // Send any Agent_OnUnload notifications
4112 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4113 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4114 extern struct JavaVM_ main_vm;
4115 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4116
4117 // Find the Agent_OnUnload function.
4118 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4119 os::find_agent_function(agent,
4120 false,
4121 on_unload_symbols,
4122 num_symbol_entries));
4123
4124 // Invoke the Agent_OnUnload function
4125 if (unload_entry != NULL) {
4126 JavaThread* thread = JavaThread::current();
4127 ThreadToNativeFromVM ttn(thread);
4128 HandleMark hm(thread);
4129 (*unload_entry)(&main_vm);
4130 }
4131 }
4132 }
4133
4134 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4135 // Invokes JVM_OnLoad
4136 void Threads::create_vm_init_libraries() {
4137 extern struct JavaVM_ main_vm;
4138 AgentLibrary* agent;
4139
4140 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4141 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4142
4143 if (on_load_entry != NULL) {
4144 // Invoke the JVM_OnLoad function
4145 JavaThread* thread = JavaThread::current();
4146 ThreadToNativeFromVM ttn(thread);
4147 HandleMark hm(thread);
4148 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4149 if (err != JNI_OK) {
4150 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4151 }
4152 } else {
4153 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4154 }
4155 }
4156 }
4157
4158
4159 // Last thread running calls java.lang.Shutdown.shutdown()
4160 void JavaThread::invoke_shutdown_hooks() {
4161 HandleMark hm(this);
4162
4163 // We could get here with a pending exception, if so clear it now.
4164 if (this->has_pending_exception()) {
4165 this->clear_pending_exception();
4166 }
4167
4168 EXCEPTION_MARK;
4169 Klass* shutdown_klass =
4170 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4171 THREAD);
4172 if (shutdown_klass != NULL) {
4173 // SystemDictionary::resolve_or_null will return null if there was
4174 // an exception. If we cannot load the Shutdown class, just don't
4175 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4176 // won't be run. Note that if a shutdown hook was registered,
4177 // the Shutdown class would have already been loaded
4178 // (Runtime.addShutdownHook will load it).
4179 JavaValue result(T_VOID);
4180 JavaCalls::call_static(&result,
4181 shutdown_klass,
4182 vmSymbols::shutdown_method_name(),
4183 vmSymbols::void_method_signature(),
4184 THREAD);
4185 }
4186 CLEAR_PENDING_EXCEPTION;
4187 }
4188
4189 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4190 // the program falls off the end of main(). Another VM exit path is through
4191 // vm_exit() when the program calls System.exit() to return a value or when
4192 // there is a serious error in VM. The two shutdown paths are not exactly
4193 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4194 // and VM_Exit op at VM level.
4195 //
4196 // Shutdown sequence:
4197 // + Shutdown native memory tracking if it is on
4198 // + Wait until we are the last non-daemon thread to execute
4199 // <-- every thing is still working at this moment -->
4200 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4201 // shutdown hooks
4202 // + Call before_exit(), prepare for VM exit
4203 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4204 // currently the only user of this mechanism is File.deleteOnExit())
4205 // > stop StatSampler, watcher thread, CMS threads,
4206 // post thread end and vm death events to JVMTI,
4207 // stop signal thread
4208 // + Call JavaThread::exit(), it will:
4209 // > release JNI handle blocks, remove stack guard pages
4210 // > remove this thread from Threads list
4211 // <-- no more Java code from this thread after this point -->
4212 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4213 // the compiler threads at safepoint
4214 // <-- do not use anything that could get blocked by Safepoint -->
4215 // + Disable tracing at JNI/JVM barriers
4216 // + Set _vm_exited flag for threads that are still running native code
4217 // + Delete this thread
4218 // + Call exit_globals()
4219 // > deletes tty
4220 // > deletes PerfMemory resources
4221 // + Return to caller
4222
4223 bool Threads::destroy_vm() {
4224 JavaThread* thread = JavaThread::current();
4225
4226 #ifdef ASSERT
4227 _vm_complete = false;
4228 #endif
4229 // Wait until we are the last non-daemon thread to execute
4230 { MutexLocker nu(Threads_lock);
4231 while (Threads::number_of_non_daemon_threads() > 1)
4232 // This wait should make safepoint checks, wait without a timeout,
4233 // and wait as a suspend-equivalent condition.
4234 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4235 Mutex::_as_suspend_equivalent_flag);
4236 }
4237
4238 EventShutdown e;
4239 if (e.should_commit()) {
4240 e.set_reason("No remaining non-daemon Java threads");
4241 e.commit();
4242 }
4243
4244 // Hang forever on exit if we are reporting an error.
4245 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4246 os::infinite_sleep();
4247 }
4248 os::wait_for_keypress_at_exit();
4249
4250 // run Java level shutdown hooks
4251 thread->invoke_shutdown_hooks();
4252
4253 before_exit(thread);
4254
4255 thread->exit(true);
4256 // thread will never call smr_delete, instead of implicit cancel
4257 // in wait_for_vm_thread_exit we do it explicit.
4258 thread->cancel_handshake();
4259
4260 // Stop VM thread.
4261 {
4262 // 4945125 The vm thread comes to a safepoint during exit.
4263 // GC vm_operations can get caught at the safepoint, and the
4264 // heap is unparseable if they are caught. Grab the Heap_lock
4265 // to prevent this. The GC vm_operations will not be able to
4266 // queue until after the vm thread is dead. After this point,
4267 // we'll never emerge out of the safepoint before the VM exits.
4268
4269 MutexLocker ml(Heap_lock);
4270
4271 VMThread::wait_for_vm_thread_exit();
4272 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4273 VMThread::destroy();
4274 }
4275
4276 // Now, all Java threads are gone except daemon threads. Daemon threads
4277 // running Java code or in VM are stopped by the Safepoint. However,
4278 // daemon threads executing native code are still running. But they
4279 // will be stopped at native=>Java/VM barriers. Note that we can't
4280 // simply kill or suspend them, as it is inherently deadlock-prone.
4281
4282 VM_Exit::set_vm_exited();
4283
4284 // Clean up ideal graph printers after the VMThread has started
4285 // the final safepoint which will block all the Compiler threads.
4286 // Note that this Thread has already logically exited so the
4287 // clean_up() function's use of a JavaThreadIteratorWithHandle
4288 // would be a problem except set_vm_exited() has remembered the
4289 // shutdown thread which is granted a policy exception.
4290 #if defined(COMPILER2) && !defined(PRODUCT)
4291 IdealGraphPrinter::clean_up();
4292 #endif
4293
4294 notify_vm_shutdown();
4295
4296 // We are after VM_Exit::set_vm_exited() so we can't call
4297 // thread->smr_delete() or we will block on the Threads_lock.
4298 // Deleting the shutdown thread here is safe because another
4299 // JavaThread cannot have an active ThreadsListHandle for
4300 // this JavaThread.
4301 delete thread;
4302
4303 #if INCLUDE_JVMCI
4304 if (JVMCICounterSize > 0) {
4305 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4306 }
4307 #endif
4308
4309 // exit_globals() will delete tty
4310 exit_globals();
4311
4312 LogConfiguration::finalize();
4313
4314 return true;
4315 }
4316
4317
4318 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4319 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4320 return is_supported_jni_version(version);
4321 }
4322
4323
4324 jboolean Threads::is_supported_jni_version(jint version) {
4325 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4326 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4327 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4328 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4329 if (version == JNI_VERSION_9) return JNI_TRUE;
4330 if (version == JNI_VERSION_10) return JNI_TRUE;
4331 return JNI_FALSE;
4332 }
4333
4334
4335 void Threads::add(JavaThread* p, bool force_daemon) {
4336 // The threads lock must be owned at this point
4337 assert_locked_or_safepoint(Threads_lock);
4338
4339 BarrierSet::barrier_set()->on_thread_attach(p);
4340
4341 p->set_next(_thread_list);
4342 _thread_list = p;
4343
4344 // Once a JavaThread is added to the Threads list, smr_delete() has
4345 // to be used to delete it. Otherwise we can just delete it directly.
4346 p->set_on_thread_list();
4347
4348 _number_of_threads++;
4349 oop threadObj = p->threadObj();
4350 bool daemon = true;
4351 // Bootstrapping problem: threadObj can be null for initial
4352 // JavaThread (or for threads attached via JNI)
4353 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4354 _number_of_non_daemon_threads++;
4355 daemon = false;
4356 }
4357
4358 ThreadService::add_thread(p, daemon);
4359
4360 // Maintain fast thread list
4361 ThreadsSMRSupport::add_thread(p);
4362
4363 // Possible GC point.
4364 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4365 }
4366
4367 void Threads::remove(JavaThread* p) {
4368
4369 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4370 ObjectSynchronizer::omFlush(p);
4371
4372 // Extra scope needed for Thread_lock, so we can check
4373 // that we do not remove thread without safepoint code notice
4374 { MutexLocker ml(Threads_lock);
4375
4376 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4377
4378 // Maintain fast thread list
4379 ThreadsSMRSupport::remove_thread(p);
4380
4381 JavaThread* current = _thread_list;
4382 JavaThread* prev = NULL;
4383
4384 while (current != p) {
4385 prev = current;
4386 current = current->next();
4387 }
4388
4389 if (prev) {
4390 prev->set_next(current->next());
4391 } else {
4392 _thread_list = p->next();
4393 }
4394
4395 _number_of_threads--;
4396 oop threadObj = p->threadObj();
4397 bool daemon = true;
4398 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4399 _number_of_non_daemon_threads--;
4400 daemon = false;
4401
4402 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4403 // on destroy_vm will wake up.
4404 if (number_of_non_daemon_threads() == 1) {
4405 Threads_lock->notify_all();
4406 }
4407 }
4408 ThreadService::remove_thread(p, daemon);
4409
4410 // Make sure that safepoint code disregard this thread. This is needed since
4411 // the thread might mess around with locks after this point. This can cause it
4412 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4413 // of this thread since it is removed from the queue.
4414 p->set_terminated_value();
4415 } // unlock Threads_lock
4416
4417 // Since Events::log uses a lock, we grab it outside the Threads_lock
4418 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4419 }
4420
4421 // Operations on the Threads list for GC. These are not explicitly locked,
4422 // but the garbage collector must provide a safe context for them to run.
4423 // In particular, these things should never be called when the Threads_lock
4424 // is held by some other thread. (Note: the Safepoint abstraction also
4425 // uses the Threads_lock to guarantee this property. It also makes sure that
4426 // all threads gets blocked when exiting or starting).
4427
4428 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4429 ALL_JAVA_THREADS(p) {
4430 p->oops_do(f, cf);
4431 }
4432 VMThread::vm_thread()->oops_do(f, cf);
4433 }
4434
4435 void Threads::change_thread_claim_parity() {
4436 // Set the new claim parity.
4437 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4438 "Not in range.");
4439 _thread_claim_parity++;
4440 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4441 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4442 "Not in range.");
4443 }
4444
4445 #ifdef ASSERT
4446 void Threads::assert_all_threads_claimed() {
4447 ALL_JAVA_THREADS(p) {
4448 const int thread_parity = p->oops_do_parity();
4449 assert((thread_parity == _thread_claim_parity),
4450 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4451 }
4452 VMThread* vmt = VMThread::vm_thread();
4453 const int thread_parity = vmt->oops_do_parity();
4454 assert((thread_parity == _thread_claim_parity),
4455 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4456 }
4457 #endif // ASSERT
4458
4459 class ParallelOopsDoThreadClosure : public ThreadClosure {
4460 private:
4461 OopClosure* _f;
4462 CodeBlobClosure* _cf;
4463 public:
4464 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4465 void do_thread(Thread* t) {
4466 t->oops_do(_f, _cf);
4467 }
4468 };
4469
4470 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4471 ParallelOopsDoThreadClosure tc(f, cf);
4472 possibly_parallel_threads_do(is_par, &tc);
4473 }
4474
4475 void Threads::nmethods_do(CodeBlobClosure* cf) {
4476 ALL_JAVA_THREADS(p) {
4477 // This is used by the code cache sweeper to mark nmethods that are active
4478 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4479 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4480 if(!p->is_Code_cache_sweeper_thread()) {
4481 p->nmethods_do(cf);
4482 }
4483 }
4484 }
4485
4486 void Threads::metadata_do(void f(Metadata*)) {
4487 ALL_JAVA_THREADS(p) {
4488 p->metadata_do(f);
4489 }
4490 }
4491
4492 class ThreadHandlesClosure : public ThreadClosure {
4493 void (*_f)(Metadata*);
4494 public:
4495 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4496 virtual void do_thread(Thread* thread) {
4497 thread->metadata_handles_do(_f);
4498 }
4499 };
4500
4501 void Threads::metadata_handles_do(void f(Metadata*)) {
4502 // Only walk the Handles in Thread.
4503 ThreadHandlesClosure handles_closure(f);
4504 threads_do(&handles_closure);
4505 }
4506
4507 void Threads::deoptimized_wrt_marked_nmethods() {
4508 ALL_JAVA_THREADS(p) {
4509 p->deoptimized_wrt_marked_nmethods();
4510 }
4511 }
4512
4513
4514 // Get count Java threads that are waiting to enter the specified monitor.
4515 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4516 int count,
4517 address monitor) {
4518 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4519
4520 int i = 0;
4521 DO_JAVA_THREADS(t_list, p) {
4522 if (!p->can_call_java()) continue;
4523
4524 address pending = (address)p->current_pending_monitor();
4525 if (pending == monitor) { // found a match
4526 if (i < count) result->append(p); // save the first count matches
4527 i++;
4528 }
4529 }
4530
4531 return result;
4532 }
4533
4534
4535 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4536 address owner) {
4537 // NULL owner means not locked so we can skip the search
4538 if (owner == NULL) return NULL;
4539
4540 DO_JAVA_THREADS(t_list, p) {
4541 // first, see if owner is the address of a Java thread
4542 if (owner == (address)p) return p;
4543 }
4544
4545 // Cannot assert on lack of success here since this function may be
4546 // used by code that is trying to report useful problem information
4547 // like deadlock detection.
4548 if (UseHeavyMonitors) return NULL;
4549
4550 // If we didn't find a matching Java thread and we didn't force use of
4551 // heavyweight monitors, then the owner is the stack address of the
4552 // Lock Word in the owning Java thread's stack.
4553 //
4554 JavaThread* the_owner = NULL;
4555 DO_JAVA_THREADS(t_list, q) {
4556 if (q->is_lock_owned(owner)) {
4557 the_owner = q;
4558 break;
4559 }
4560 }
4561
4562 // cannot assert on lack of success here; see above comment
4563 return the_owner;
4564 }
4565
4566 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4567 void Threads::print_on(outputStream* st, bool print_stacks,
4568 bool internal_format, bool print_concurrent_locks,
4569 bool print_extended_info) {
4570 char buf[32];
4571 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4572
4573 st->print_cr("Full thread dump %s (%s %s):",
4574 Abstract_VM_Version::vm_name(),
4575 Abstract_VM_Version::vm_release(),
4576 Abstract_VM_Version::vm_info_string());
4577 st->cr();
4578
4579 #if INCLUDE_SERVICES
4580 // Dump concurrent locks
4581 ConcurrentLocksDump concurrent_locks;
4582 if (print_concurrent_locks) {
4583 concurrent_locks.dump_at_safepoint();
4584 }
4585 #endif // INCLUDE_SERVICES
4586
4587 ThreadsSMRSupport::print_info_on(st);
4588 st->cr();
4589
4590 ALL_JAVA_THREADS(p) {
4591 ResourceMark rm;
4592 p->print_on(st, print_extended_info);
4593 if (print_stacks) {
4594 if (internal_format) {
4595 p->trace_stack();
4596 } else {
4597 p->print_stack_on(st);
4598 }
4599 }
4600 st->cr();
4601 #if INCLUDE_SERVICES
4602 if (print_concurrent_locks) {
4603 concurrent_locks.print_locks_on(p, st);
4604 }
4605 #endif // INCLUDE_SERVICES
4606 }
4607
4608 VMThread::vm_thread()->print_on(st);
4609 st->cr();
4610 Universe::heap()->print_gc_threads_on(st);
4611 WatcherThread* wt = WatcherThread::watcher_thread();
4612 if (wt != NULL) {
4613 wt->print_on(st);
4614 st->cr();
4615 }
4616
4617 st->flush();
4618 }
4619
4620 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4621 int buflen, bool* found_current) {
4622 if (this_thread != NULL) {
4623 bool is_current = (current == this_thread);
4624 *found_current = *found_current || is_current;
4625 st->print("%s", is_current ? "=>" : " ");
4626
4627 st->print(PTR_FORMAT, p2i(this_thread));
4628 st->print(" ");
4629 this_thread->print_on_error(st, buf, buflen);
4630 st->cr();
4631 }
4632 }
4633
4634 class PrintOnErrorClosure : public ThreadClosure {
4635 outputStream* _st;
4636 Thread* _current;
4637 char* _buf;
4638 int _buflen;
4639 bool* _found_current;
4640 public:
4641 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4642 int buflen, bool* found_current) :
4643 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4644
4645 virtual void do_thread(Thread* thread) {
4646 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4647 }
4648 };
4649
4650 // Threads::print_on_error() is called by fatal error handler. It's possible
4651 // that VM is not at safepoint and/or current thread is inside signal handler.
4652 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4653 // memory (even in resource area), it might deadlock the error handler.
4654 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4655 int buflen) {
4656 ThreadsSMRSupport::print_info_on(st);
4657 st->cr();
4658
4659 bool found_current = false;
4660 st->print_cr("Java Threads: ( => current thread )");
4661 ALL_JAVA_THREADS(thread) {
4662 print_on_error(thread, st, current, buf, buflen, &found_current);
4663 }
4664 st->cr();
4665
4666 st->print_cr("Other Threads:");
4667 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4668 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4669
4670 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4671 Universe::heap()->gc_threads_do(&print_closure);
4672
4673 if (!found_current) {
4674 st->cr();
4675 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4676 current->print_on_error(st, buf, buflen);
4677 st->cr();
4678 }
4679 st->cr();
4680
4681 st->print_cr("Threads with active compile tasks:");
4682 print_threads_compiling(st, buf, buflen);
4683 }
4684
4685 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4686 ALL_JAVA_THREADS(thread) {
4687 if (thread->is_Compiler_thread()) {
4688 CompilerThread* ct = (CompilerThread*) thread;
4689
4690 // Keep task in local variable for NULL check.
4691 // ct->_task might be set to NULL by concurring compiler thread
4692 // because it completed the compilation. The task is never freed,
4693 // though, just returned to a free list.
4694 CompileTask* task = ct->task();
4695 if (task != NULL) {
4696 thread->print_name_on_error(st, buf, buflen);
4697 task->print(st, NULL, true, true);
4698 }
4699 }
4700 }
4701 }
4702
4703
4704 // Internal SpinLock and Mutex
4705 // Based on ParkEvent
4706
4707 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4708 //
4709 // We employ SpinLocks _only for low-contention, fixed-length
4710 // short-duration critical sections where we're concerned
4711 // about native mutex_t or HotSpot Mutex:: latency.
4712 // The mux construct provides a spin-then-block mutual exclusion
4713 // mechanism.
4714 //
4715 // Testing has shown that contention on the ListLock guarding gFreeList
4716 // is common. If we implement ListLock as a simple SpinLock it's common
4717 // for the JVM to devolve to yielding with little progress. This is true
4718 // despite the fact that the critical sections protected by ListLock are
4719 // extremely short.
4720 //
4721 // TODO-FIXME: ListLock should be of type SpinLock.
4722 // We should make this a 1st-class type, integrated into the lock
4723 // hierarchy as leaf-locks. Critically, the SpinLock structure
4724 // should have sufficient padding to avoid false-sharing and excessive
4725 // cache-coherency traffic.
4726
4727
4728 typedef volatile int SpinLockT;
4729
4730 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4731 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4732 return; // normal fast-path return
4733 }
4734
4735 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4736 int ctr = 0;
4737 int Yields = 0;
4738 for (;;) {
4739 while (*adr != 0) {
4740 ++ctr;
4741 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4742 if (Yields > 5) {
4743 os::naked_short_sleep(1);
4744 } else {
4745 os::naked_yield();
4746 ++Yields;
4747 }
4748 } else {
4749 SpinPause();
4750 }
4751 }
4752 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4753 }
4754 }
4755
4756 void Thread::SpinRelease(volatile int * adr) {
4757 assert(*adr != 0, "invariant");
4758 OrderAccess::fence(); // guarantee at least release consistency.
4759 // Roach-motel semantics.
4760 // It's safe if subsequent LDs and STs float "up" into the critical section,
4761 // but prior LDs and STs within the critical section can't be allowed
4762 // to reorder or float past the ST that releases the lock.
4763 // Loads and stores in the critical section - which appear in program
4764 // order before the store that releases the lock - must also appear
4765 // before the store that releases the lock in memory visibility order.
4766 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4767 // the ST of 0 into the lock-word which releases the lock, so fence
4768 // more than covers this on all platforms.
4769 *adr = 0;
4770 }
4771
4772 // muxAcquire and muxRelease:
4773 //
4774 // * muxAcquire and muxRelease support a single-word lock-word construct.
4775 // The LSB of the word is set IFF the lock is held.
4776 // The remainder of the word points to the head of a singly-linked list
4777 // of threads blocked on the lock.
4778 //
4779 // * The current implementation of muxAcquire-muxRelease uses its own
4780 // dedicated Thread._MuxEvent instance. If we're interested in
4781 // minimizing the peak number of extant ParkEvent instances then
4782 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4783 // as certain invariants were satisfied. Specifically, care would need
4784 // to be taken with regards to consuming unpark() "permits".
4785 // A safe rule of thumb is that a thread would never call muxAcquire()
4786 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4787 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4788 // consume an unpark() permit intended for monitorenter, for instance.
4789 // One way around this would be to widen the restricted-range semaphore
4790 // implemented in park(). Another alternative would be to provide
4791 // multiple instances of the PlatformEvent() for each thread. One
4792 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4793 //
4794 // * Usage:
4795 // -- Only as leaf locks
4796 // -- for short-term locking only as muxAcquire does not perform
4797 // thread state transitions.
4798 //
4799 // Alternatives:
4800 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4801 // but with parking or spin-then-park instead of pure spinning.
4802 // * Use Taura-Oyama-Yonenzawa locks.
4803 // * It's possible to construct a 1-0 lock if we encode the lockword as
4804 // (List,LockByte). Acquire will CAS the full lockword while Release
4805 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4806 // acquiring threads use timers (ParkTimed) to detect and recover from
4807 // the stranding window. Thread/Node structures must be aligned on 256-byte
4808 // boundaries by using placement-new.
4809 // * Augment MCS with advisory back-link fields maintained with CAS().
4810 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4811 // The validity of the backlinks must be ratified before we trust the value.
4812 // If the backlinks are invalid the exiting thread must back-track through the
4813 // the forward links, which are always trustworthy.
4814 // * Add a successor indication. The LockWord is currently encoded as
4815 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4816 // to provide the usual futile-wakeup optimization.
4817 // See RTStt for details.
4818 //
4819
4820
4821 const intptr_t LOCKBIT = 1;
4822
4823 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4824 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4825 if (w == 0) return;
4826 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4827 return;
4828 }
4829
4830 ParkEvent * const Self = Thread::current()->_MuxEvent;
4831 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4832 for (;;) {
4833 int its = (os::is_MP() ? 100 : 0) + 1;
4834
4835 // Optional spin phase: spin-then-park strategy
4836 while (--its >= 0) {
4837 w = *Lock;
4838 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4839 return;
4840 }
4841 }
4842
4843 Self->reset();
4844 Self->OnList = intptr_t(Lock);
4845 // The following fence() isn't _strictly necessary as the subsequent
4846 // CAS() both serializes execution and ratifies the fetched *Lock value.
4847 OrderAccess::fence();
4848 for (;;) {
4849 w = *Lock;
4850 if ((w & LOCKBIT) == 0) {
4851 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4852 Self->OnList = 0; // hygiene - allows stronger asserts
4853 return;
4854 }
4855 continue; // Interference -- *Lock changed -- Just retry
4856 }
4857 assert(w & LOCKBIT, "invariant");
4858 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4859 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4860 }
4861
4862 while (Self->OnList != 0) {
4863 Self->park();
4864 }
4865 }
4866 }
4867
4868 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4869 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4870 if (w == 0) return;
4871 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4872 return;
4873 }
4874
4875 ParkEvent * ReleaseAfter = NULL;
4876 if (ev == NULL) {
4877 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4878 }
4879 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4880 for (;;) {
4881 guarantee(ev->OnList == 0, "invariant");
4882 int its = (os::is_MP() ? 100 : 0) + 1;
4883
4884 // Optional spin phase: spin-then-park strategy
4885 while (--its >= 0) {
4886 w = *Lock;
4887 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4888 if (ReleaseAfter != NULL) {
4889 ParkEvent::Release(ReleaseAfter);
4890 }
4891 return;
4892 }
4893 }
4894
4895 ev->reset();
4896 ev->OnList = intptr_t(Lock);
4897 // The following fence() isn't _strictly necessary as the subsequent
4898 // CAS() both serializes execution and ratifies the fetched *Lock value.
4899 OrderAccess::fence();
4900 for (;;) {
4901 w = *Lock;
4902 if ((w & LOCKBIT) == 0) {
4903 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4904 ev->OnList = 0;
4905 // We call ::Release while holding the outer lock, thus
4906 // artificially lengthening the critical section.
4907 // Consider deferring the ::Release() until the subsequent unlock(),
4908 // after we've dropped the outer lock.
4909 if (ReleaseAfter != NULL) {
4910 ParkEvent::Release(ReleaseAfter);
4911 }
4912 return;
4913 }
4914 continue; // Interference -- *Lock changed -- Just retry
4915 }
4916 assert(w & LOCKBIT, "invariant");
4917 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4918 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4919 }
4920
4921 while (ev->OnList != 0) {
4922 ev->park();
4923 }
4924 }
4925 }
4926
4927 // Release() must extract a successor from the list and then wake that thread.
4928 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4929 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4930 // Release() would :
4931 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4932 // (B) Extract a successor from the private list "in-hand"
4933 // (C) attempt to CAS() the residual back into *Lock over null.
4934 // If there were any newly arrived threads and the CAS() would fail.
4935 // In that case Release() would detach the RATs, re-merge the list in-hand
4936 // with the RATs and repeat as needed. Alternately, Release() might
4937 // detach and extract a successor, but then pass the residual list to the wakee.
4938 // The wakee would be responsible for reattaching and remerging before it
4939 // competed for the lock.
4940 //
4941 // Both "pop" and DMR are immune from ABA corruption -- there can be
4942 // multiple concurrent pushers, but only one popper or detacher.
4943 // This implementation pops from the head of the list. This is unfair,
4944 // but tends to provide excellent throughput as hot threads remain hot.
4945 // (We wake recently run threads first).
4946 //
4947 // All paths through muxRelease() will execute a CAS.
4948 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4949 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4950 // executed within the critical section are complete and globally visible before the
4951 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4952 void Thread::muxRelease(volatile intptr_t * Lock) {
4953 for (;;) {
4954 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4955 assert(w & LOCKBIT, "invariant");
4956 if (w == LOCKBIT) return;
4957 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4958 assert(List != NULL, "invariant");
4959 assert(List->OnList == intptr_t(Lock), "invariant");
4960 ParkEvent * const nxt = List->ListNext;
4961 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4962
4963 // The following CAS() releases the lock and pops the head element.
4964 // The CAS() also ratifies the previously fetched lock-word value.
4965 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4966 continue;
4967 }
4968 List->OnList = 0;
4969 OrderAccess::fence();
4970 List->unpark();
4971 return;
4972 }
4973 }
4974
4975
4976 void Threads::verify() {
4977 ALL_JAVA_THREADS(p) {
4978 p->verify();
4979 }
4980 VMThread* thread = VMThread::vm_thread();
4981 if (thread != NULL) thread->verify();
4982 }