1 /*
2 * Copyright (c) 1997, 2020, 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 "aot/aotLoader.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/javaClasses.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/scopeDesc.hpp"
35 #include "compiler/compileBroker.hpp"
36 #include "compiler/compileTask.hpp"
37 #include "gc/shared/barrierSet.hpp"
38 #include "gc/shared/gcId.hpp"
39 #include "gc/shared/gcLocker.inline.hpp"
40 #include "gc/shared/oopStorage.hpp"
41 #include "gc/shared/oopStorageSet.hpp"
42 #include "gc/shared/workgroup.hpp"
43 #include "interpreter/interpreter.hpp"
44 #include "interpreter/linkResolver.hpp"
45 #include "interpreter/oopMapCache.hpp"
46 #include "jfr/jfrEvents.hpp"
47 #include "jvmtifiles/jvmtiEnv.hpp"
48 #include "logging/log.hpp"
49 #include "logging/logConfiguration.hpp"
50 #include "logging/logStream.hpp"
51 #include "memory/allocation.inline.hpp"
52 #include "memory/iterator.hpp"
53 #include "memory/metaspaceShared.hpp"
54 #include "memory/oopFactory.hpp"
55 #include "memory/resourceArea.hpp"
56 #include "memory/universe.hpp"
57 #include "oops/access.inline.hpp"
58 #include "oops/instanceKlass.hpp"
59 #include "oops/objArrayOop.hpp"
60 #include "oops/oop.inline.hpp"
61 #include "oops/symbol.hpp"
62 #include "oops/typeArrayOop.inline.hpp"
63 #include "oops/verifyOopClosure.hpp"
64 #include "prims/jvm_misc.hpp"
65 #include "prims/jvmtiExport.hpp"
66 #include "prims/jvmtiThreadState.hpp"
67 #include "runtime/arguments.hpp"
68 #include "runtime/atomic.hpp"
69 #include "runtime/biasedLocking.hpp"
70 #include "runtime/fieldDescriptor.inline.hpp"
71 #include "runtime/flags/jvmFlagConstraintList.hpp"
72 #include "runtime/flags/jvmFlagRangeList.hpp"
73 #include "runtime/deoptimization.hpp"
74 #include "runtime/frame.inline.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/handshake.hpp"
77 #include "runtime/init.hpp"
78 #include "runtime/interfaceSupport.inline.hpp"
79 #include "runtime/java.hpp"
80 #include "runtime/javaCalls.hpp"
81 #include "runtime/jniHandles.inline.hpp"
82 #include "runtime/jniPeriodicChecker.hpp"
83 #include "runtime/memprofiler.hpp"
84 #include "runtime/mutexLocker.hpp"
85 #include "runtime/objectMonitor.hpp"
86 #include "runtime/orderAccess.hpp"
87 #include "runtime/osThread.hpp"
88 #include "runtime/prefetch.inline.hpp"
89 #include "runtime/safepoint.hpp"
90 #include "runtime/safepointMechanism.inline.hpp"
91 #include "runtime/safepointVerifiers.hpp"
92 #include "runtime/serviceThread.hpp"
93 #include "runtime/sharedRuntime.hpp"
94 #include "runtime/statSampler.hpp"
95 #include "runtime/stubRoutines.hpp"
96 #include "runtime/sweeper.hpp"
97 #include "runtime/task.hpp"
98 #include "runtime/thread.inline.hpp"
99 #include "runtime/threadCritical.hpp"
100 #include "runtime/threadSMR.inline.hpp"
101 #include "runtime/threadStatisticalInfo.hpp"
102 #include "runtime/timer.hpp"
103 #include "runtime/timerTrace.hpp"
104 #include "runtime/vframe.inline.hpp"
105 #include "runtime/vframeArray.hpp"
106 #include "runtime/vframe_hp.hpp"
107 #include "runtime/vmThread.hpp"
108 #include "runtime/vmOperations.hpp"
109 #include "runtime/vm_version.hpp"
110 #include "services/attachListener.hpp"
111 #include "services/management.hpp"
112 #include "services/memTracker.hpp"
113 #include "services/threadService.hpp"
114 #include "utilities/align.hpp"
115 #include "utilities/copy.hpp"
116 #include "utilities/defaultStream.hpp"
117 #include "utilities/dtrace.hpp"
118 #include "utilities/events.hpp"
119 #include "utilities/macros.hpp"
120 #include "utilities/preserveException.hpp"
121 #include "utilities/singleWriterSynchronizer.hpp"
122 #include "utilities/vmError.hpp"
123 #if INCLUDE_JVMCI
124 #include "jvmci/jvmci.hpp"
125 #include "jvmci/jvmciEnv.hpp"
126 #endif
127 #ifdef COMPILER1
128 #include "c1/c1_Compiler.hpp"
129 #endif
130 #ifdef COMPILER2
131 #include "opto/c2compiler.hpp"
132 #include "opto/idealGraphPrinter.hpp"
133 #endif
134 #if INCLUDE_RTM_OPT
135 #include "runtime/rtmLocking.hpp"
136 #endif
137 #if INCLUDE_JFR
138 #include "jfr/jfr.hpp"
139 #endif
140
141 // Initialization after module runtime initialization
142 void universe_post_module_init(); // must happen after call_initPhase2
143
144 #ifdef DTRACE_ENABLED
145
146 // Only bother with this argument setup if dtrace is available
147
148 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
149 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
150
151 #define DTRACE_THREAD_PROBE(probe, javathread) \
152 { \
153 ResourceMark rm(this); \
154 int len = 0; \
155 const char* name = (javathread)->get_thread_name(); \
156 len = strlen(name); \
157 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
158 (char *) name, len, \
159 java_lang_Thread::thread_id((javathread)->threadObj()), \
160 (uintptr_t) (javathread)->osthread()->thread_id(), \
161 java_lang_Thread::is_daemon((javathread)->threadObj())); \
162 }
163
164 #else // ndef DTRACE_ENABLED
165
166 #define DTRACE_THREAD_PROBE(probe, javathread)
167
168 #endif // ndef DTRACE_ENABLED
169
170 #ifndef USE_LIBRARY_BASED_TLS_ONLY
171 // Current thread is maintained as a thread-local variable
172 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
173 #endif
174
175 // ======= Thread ========
176 // Support for forcing alignment of thread objects for biased locking
177 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
178 if (UseBiasedLocking) {
179 const size_t alignment = markWord::biased_lock_alignment;
180 size_t aligned_size = size + (alignment - sizeof(intptr_t));
181 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
182 : AllocateHeap(aligned_size, flags, CURRENT_PC,
183 AllocFailStrategy::RETURN_NULL);
184 void* aligned_addr = align_up(real_malloc_addr, alignment);
185 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
186 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
187 "JavaThread alignment code overflowed allocated storage");
188 if (aligned_addr != real_malloc_addr) {
189 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
190 p2i(real_malloc_addr),
191 p2i(aligned_addr));
192 }
193 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
194 return aligned_addr;
195 } else {
196 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
197 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
198 }
199 }
200
201 void Thread::operator delete(void* p) {
202 if (UseBiasedLocking) {
203 FreeHeap(((Thread*) p)->_real_malloc_address);
204 } else {
205 FreeHeap(p);
206 }
207 }
208
209 void JavaThread::smr_delete() {
210 if (_on_thread_list) {
211 ThreadsSMRSupport::smr_delete(this);
212 } else {
213 delete this;
214 }
215 }
216
217 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
218 // JavaThread
219
220 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
221
222 Thread::Thread() {
223
224 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
225
226 // stack and get_thread
227 set_stack_base(NULL);
228 set_stack_size(0);
229 set_lgrp_id(-1);
230 DEBUG_ONLY(clear_suspendible_thread();)
231
232 // allocated data structures
233 set_osthread(NULL);
234 set_resource_area(new (mtThread)ResourceArea());
235 DEBUG_ONLY(_current_resource_mark = NULL;)
236 set_handle_area(new (mtThread) HandleArea(NULL));
237 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, mtClass));
238 set_active_handles(NULL);
239 set_free_handle_block(NULL);
240 set_last_handle_mark(NULL);
241 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
242
243 // Initial value of zero ==> never claimed.
244 _threads_do_token = 0;
245 _threads_hazard_ptr = NULL;
246 _threads_list_ptr = NULL;
247 _nested_threads_hazard_ptr_cnt = 0;
248 _rcu_counter = 0;
249
250 // the handle mark links itself to last_handle_mark
251 new HandleMark(this);
252
253 // plain initialization
254 debug_only(_owned_locks = NULL;)
255 NOT_PRODUCT(_no_safepoint_count = 0;)
256 NOT_PRODUCT(_skip_gcalot = false;)
257 _jvmti_env_iteration_count = 0;
258 set_allocated_bytes(0);
259 _vm_operation_started_count = 0;
260 _vm_operation_completed_count = 0;
261 _current_pending_monitor = NULL;
262 _current_pending_monitor_is_from_java = true;
263 _current_waiting_monitor = NULL;
264 _current_pending_raw_monitor = NULL;
265 _num_nested_signal = 0;
266 om_free_list = NULL;
267 om_free_count = 0;
268 om_free_provision = 32;
269 om_in_use_list = NULL;
270 om_in_use_count = 0;
271
272 #ifdef ASSERT
273 _visited_for_critical_count = false;
274 #endif
275
276 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
277 Monitor::_safepoint_check_sometimes);
278 _suspend_flags = 0;
279
280 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
281 _hashStateX = os::random();
282 _hashStateY = 842502087;
283 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
284 _hashStateW = 273326509;
285
286 _OnTrap = 0;
287 _Stalled = 0;
288 _TypeTag = 0x2BAD;
289
290 // Many of the following fields are effectively final - immutable
291 // Note that nascent threads can't use the Native Monitor-Mutex
292 // construct until the _MutexEvent is initialized ...
293 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
294 // we might instead use a stack of ParkEvents that we could provision on-demand.
295 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
296 // and ::Release()
297 _ParkEvent = ParkEvent::Allocate(this);
298 _MuxEvent = ParkEvent::Allocate(this);
299
300 #ifdef CHECK_UNHANDLED_OOPS
301 if (CheckUnhandledOops) {
302 _unhandled_oops = new UnhandledOops(this);
303 }
304 #endif // CHECK_UNHANDLED_OOPS
305 #ifdef ASSERT
306 if (UseBiasedLocking) {
307 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
308 assert(this == _real_malloc_address ||
309 this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
310 "bug in forced alignment of thread objects");
311 }
312 #endif // ASSERT
313
314 // Notify the barrier set that a thread is being created. The initial
315 // thread is created before the barrier set is available. The call to
316 // BarrierSet::on_thread_create() for this thread is therefore deferred
317 // to BarrierSet::set_barrier_set().
318 BarrierSet* const barrier_set = BarrierSet::barrier_set();
319 if (barrier_set != NULL) {
320 barrier_set->on_thread_create(this);
321 } else {
322 // Only the main thread should be created before the barrier set
323 // and that happens just before Thread::current is set. No other thread
324 // can attach as the VM is not created yet, so they can't execute this code.
325 // If the main thread creates other threads before the barrier set that is an error.
326 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
327 }
328 }
329
330 void Thread::initialize_thread_current() {
331 #ifndef USE_LIBRARY_BASED_TLS_ONLY
332 assert(_thr_current == NULL, "Thread::current already initialized");
333 _thr_current = this;
334 #endif
335 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
336 ThreadLocalStorage::set_thread(this);
337 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
338 }
339
340 void Thread::clear_thread_current() {
341 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
342 #ifndef USE_LIBRARY_BASED_TLS_ONLY
343 _thr_current = NULL;
344 #endif
345 ThreadLocalStorage::set_thread(NULL);
346 }
347
348 void Thread::record_stack_base_and_size() {
349 // Note: at this point, Thread object is not yet initialized. Do not rely on
350 // any members being initialized. Do not rely on Thread::current() being set.
351 // If possible, refrain from doing anything which may crash or assert since
352 // quite probably those crash dumps will be useless.
353 set_stack_base(os::current_stack_base());
354 set_stack_size(os::current_stack_size());
355
356 // Set stack limits after thread is initialized.
357 if (is_Java_thread()) {
358 ((JavaThread*) this)->set_stack_overflow_limit();
359 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
360 }
361 }
362
363 #if INCLUDE_NMT
364 void Thread::register_thread_stack_with_NMT() {
365 MemTracker::record_thread_stack(stack_end(), stack_size());
366 }
367 #endif // INCLUDE_NMT
368
369 void Thread::call_run() {
370 DEBUG_ONLY(_run_state = CALL_RUN;)
371
372 // At this point, Thread object should be fully initialized and
373 // Thread::current() should be set.
374
375 assert(Thread::current_or_null() != NULL, "current thread is unset");
376 assert(Thread::current_or_null() == this, "current thread is wrong");
377
378 // Perform common initialization actions
379
380 register_thread_stack_with_NMT();
381
382 JFR_ONLY(Jfr::on_thread_start(this);)
383
384 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
385 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
386 os::current_thread_id(), p2i(stack_end()),
387 p2i(stack_base()), stack_size()/1024);
388
389 // Perform <ChildClass> initialization actions
390 DEBUG_ONLY(_run_state = PRE_RUN;)
391 this->pre_run();
392
393 // Invoke <ChildClass>::run()
394 DEBUG_ONLY(_run_state = RUN;)
395 this->run();
396 // Returned from <ChildClass>::run(). Thread finished.
397
398 // Perform common tear-down actions
399
400 assert(Thread::current_or_null() != NULL, "current thread is unset");
401 assert(Thread::current_or_null() == this, "current thread is wrong");
402
403 // Perform <ChildClass> tear-down actions
404 DEBUG_ONLY(_run_state = POST_RUN;)
405 this->post_run();
406
407 // Note: at this point the thread object may already have deleted itself,
408 // so from here on do not dereference *this*. Not all thread types currently
409 // delete themselves when they terminate. But no thread should ever be deleted
410 // asynchronously with respect to its termination - that is what _run_state can
411 // be used to check.
412
413 assert(Thread::current_or_null() == NULL, "current thread still present");
414 }
415
416 Thread::~Thread() {
417
418 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
419 // get started due to errors etc. Any active thread should at least reach post_run
420 // before it is deleted (usually in post_run()).
421 assert(_run_state == PRE_CALL_RUN ||
422 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
423 "_run_state=%d", (int)_run_state);
424
425 // Notify the barrier set that a thread is being destroyed. Note that a barrier
426 // set might not be available if we encountered errors during bootstrapping.
427 BarrierSet* const barrier_set = BarrierSet::barrier_set();
428 if (barrier_set != NULL) {
429 barrier_set->on_thread_destroy(this);
430 }
431
432 // stack_base can be NULL if the thread is never started or exited before
433 // record_stack_base_and_size called. Although, we would like to ensure
434 // that all started threads do call record_stack_base_and_size(), there is
435 // not proper way to enforce that.
436 #if INCLUDE_NMT
437 if (_stack_base != NULL) {
438 MemTracker::release_thread_stack(stack_end(), stack_size());
439 #ifdef ASSERT
440 set_stack_base(NULL);
441 #endif
442 }
443 #endif // INCLUDE_NMT
444
445 // deallocate data structures
446 delete resource_area();
447 // since the handle marks are using the handle area, we have to deallocated the root
448 // handle mark before deallocating the thread's handle area,
449 assert(last_handle_mark() != NULL, "check we have an element");
450 delete last_handle_mark();
451 assert(last_handle_mark() == NULL, "check we have reached the end");
452
453 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
454 // We NULL out the fields for good hygiene.
455 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
456 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
457
458 delete handle_area();
459 delete metadata_handles();
460
461 // SR_handler uses this as a termination indicator -
462 // needs to happen before os::free_thread()
463 delete _SR_lock;
464 _SR_lock = NULL;
465
466 // osthread() can be NULL, if creation of thread failed.
467 if (osthread() != NULL) os::free_thread(osthread());
468
469 // Clear Thread::current if thread is deleting itself and it has not
470 // already been done. This must be done before the memory is deallocated.
471 // Needed to ensure JNI correctly detects non-attached threads.
472 if (this == Thread::current_or_null()) {
473 Thread::clear_thread_current();
474 }
475
476 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
477 }
478
479 #ifdef ASSERT
480 // A JavaThread is considered "dangling" if it is not the current
481 // thread, has been added the Threads list, the system is not at a
482 // safepoint and the Thread is not "protected".
483 //
484 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
485 assert(!thread->is_Java_thread() || Thread::current() == thread ||
486 !((JavaThread *) thread)->on_thread_list() ||
487 SafepointSynchronize::is_at_safepoint() ||
488 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
489 "possibility of dangling Thread pointer");
490 }
491 #endif
492
493 ThreadPriority Thread::get_priority(const Thread* const thread) {
494 ThreadPriority priority;
495 // Can return an error!
496 (void)os::get_priority(thread, priority);
497 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
498 return priority;
499 }
500
501 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
502 debug_only(check_for_dangling_thread_pointer(thread);)
503 // Can return an error!
504 (void)os::set_priority(thread, priority);
505 }
506
507
508 void Thread::start(Thread* thread) {
509 // Start is different from resume in that its safety is guaranteed by context or
510 // being called from a Java method synchronized on the Thread object.
511 if (!DisableStartThread) {
512 if (thread->is_Java_thread()) {
513 // Initialize the thread state to RUNNABLE before starting this thread.
514 // Can not set it after the thread started because we do not know the
515 // exact thread state at that time. It could be in MONITOR_WAIT or
516 // in SLEEPING or some other state.
517 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
518 java_lang_Thread::RUNNABLE);
519 }
520 os::start_thread(thread);
521 }
522 }
523
524 class InstallAsyncExceptionClosure : public HandshakeClosure {
525 Handle _throwable; // The Throwable thrown at the target Thread
526 public:
527 InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
528
529 void do_thread(Thread* thr) {
530 JavaThread* target = (JavaThread*)thr;
531 // Note that this now allows multiple ThreadDeath exceptions to be
532 // thrown at a thread.
533 // The target thread has run and has not exited yet.
534 target->send_thread_stop(_throwable());
535 }
536 };
537
538 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
539 Handle throwable(Thread::current(), java_throwable);
540 JavaThread* target = java_lang_Thread::thread(java_thread);
541 InstallAsyncExceptionClosure vm_stop(throwable);
542 Handshake::execute(&vm_stop, target);
543 }
544
545
546 // Check if an external suspend request has completed (or has been
547 // cancelled). Returns true if the thread is externally suspended and
548 // false otherwise.
549 //
550 // The bits parameter returns information about the code path through
551 // the routine. Useful for debugging:
552 //
553 // set in is_ext_suspend_completed():
554 // 0x00000001 - routine was entered
555 // 0x00000010 - routine return false at end
556 // 0x00000100 - thread exited (return false)
557 // 0x00000200 - suspend request cancelled (return false)
558 // 0x00000400 - thread suspended (return true)
559 // 0x00001000 - thread is in a suspend equivalent state (return true)
560 // 0x00002000 - thread is native and walkable (return true)
561 // 0x00004000 - thread is native_trans and walkable (needed retry)
562 //
563 // set in wait_for_ext_suspend_completion():
564 // 0x00010000 - routine was entered
565 // 0x00020000 - suspend request cancelled before loop (return false)
566 // 0x00040000 - thread suspended before loop (return true)
567 // 0x00080000 - suspend request cancelled in loop (return false)
568 // 0x00100000 - thread suspended in loop (return true)
569 // 0x00200000 - suspend not completed during retry loop (return false)
570
571 // Helper class for tracing suspend wait debug bits.
572 //
573 // 0x00000100 indicates that the target thread exited before it could
574 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
575 // 0x00080000 each indicate a cancelled suspend request so they don't
576 // count as wait failures either.
577 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
578
579 class TraceSuspendDebugBits : public StackObj {
580 private:
581 JavaThread * jt;
582 bool is_wait;
583 bool called_by_wait; // meaningful when !is_wait
584 uint32_t * bits;
585
586 public:
587 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
588 uint32_t *_bits) {
589 jt = _jt;
590 is_wait = _is_wait;
591 called_by_wait = _called_by_wait;
592 bits = _bits;
593 }
594
595 ~TraceSuspendDebugBits() {
596 if (!is_wait) {
597 #if 1
598 // By default, don't trace bits for is_ext_suspend_completed() calls.
599 // That trace is very chatty.
600 return;
601 #else
602 if (!called_by_wait) {
603 // If tracing for is_ext_suspend_completed() is enabled, then only
604 // trace calls to it from wait_for_ext_suspend_completion()
605 return;
606 }
607 #endif
608 }
609
610 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
611 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
612 MutexLocker ml(Threads_lock); // needed for get_thread_name()
613 ResourceMark rm;
614
615 tty->print_cr(
616 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
617 jt->get_thread_name(), *bits);
618
619 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
620 }
621 }
622 }
623 };
624 #undef DEBUG_FALSE_BITS
625
626
627 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
628 uint32_t *bits) {
629 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
630
631 bool did_trans_retry = false; // only do thread_in_native_trans retry once
632 bool do_trans_retry; // flag to force the retry
633
634 *bits |= 0x00000001;
635
636 do {
637 do_trans_retry = false;
638
639 if (is_exiting()) {
640 // Thread is in the process of exiting. This is always checked
641 // first to reduce the risk of dereferencing a freed JavaThread.
642 *bits |= 0x00000100;
643 return false;
644 }
645
646 if (!is_external_suspend()) {
647 // Suspend request is cancelled. This is always checked before
648 // is_ext_suspended() to reduce the risk of a rogue resume
649 // confusing the thread that made the suspend request.
650 *bits |= 0x00000200;
651 return false;
652 }
653
654 if (is_ext_suspended()) {
655 // thread is suspended
656 *bits |= 0x00000400;
657 return true;
658 }
659
660 // Now that we no longer do hard suspends of threads running
661 // native code, the target thread can be changing thread state
662 // while we are in this routine:
663 //
664 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
665 //
666 // We save a copy of the thread state as observed at this moment
667 // and make our decision about suspend completeness based on the
668 // copy. This closes the race where the thread state is seen as
669 // _thread_in_native_trans in the if-thread_blocked check, but is
670 // seen as _thread_blocked in if-thread_in_native_trans check.
671 JavaThreadState save_state = thread_state();
672
673 if (save_state == _thread_blocked && is_suspend_equivalent()) {
674 // If the thread's state is _thread_blocked and this blocking
675 // condition is known to be equivalent to a suspend, then we can
676 // consider the thread to be externally suspended. This means that
677 // the code that sets _thread_blocked has been modified to do
678 // self-suspension if the blocking condition releases. We also
679 // used to check for CONDVAR_WAIT here, but that is now covered by
680 // the _thread_blocked with self-suspension check.
681 //
682 // Return true since we wouldn't be here unless there was still an
683 // external suspend request.
684 *bits |= 0x00001000;
685 return true;
686 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
687 // Threads running native code will self-suspend on native==>VM/Java
688 // transitions. If its stack is walkable (should always be the case
689 // unless this function is called before the actual java_suspend()
690 // call), then the wait is done.
691 *bits |= 0x00002000;
692 return true;
693 } else if (!called_by_wait && !did_trans_retry &&
694 save_state == _thread_in_native_trans &&
695 frame_anchor()->walkable()) {
696 // The thread is transitioning from thread_in_native to another
697 // thread state. check_safepoint_and_suspend_for_native_trans()
698 // will force the thread to self-suspend. If it hasn't gotten
699 // there yet we may have caught the thread in-between the native
700 // code check above and the self-suspend. Lucky us. If we were
701 // called by wait_for_ext_suspend_completion(), then it
702 // will be doing the retries so we don't have to.
703 //
704 // Since we use the saved thread state in the if-statement above,
705 // there is a chance that the thread has already transitioned to
706 // _thread_blocked by the time we get here. In that case, we will
707 // make a single unnecessary pass through the logic below. This
708 // doesn't hurt anything since we still do the trans retry.
709
710 *bits |= 0x00004000;
711
712 // Once the thread leaves thread_in_native_trans for another
713 // thread state, we break out of this retry loop. We shouldn't
714 // need this flag to prevent us from getting back here, but
715 // sometimes paranoia is good.
716 did_trans_retry = true;
717
718 // We wait for the thread to transition to a more usable state.
719 for (int i = 1; i <= SuspendRetryCount; i++) {
720 // We used to do an "os::yield_all(i)" call here with the intention
721 // that yielding would increase on each retry. However, the parameter
722 // is ignored on Linux which means the yield didn't scale up. Waiting
723 // on the SR_lock below provides a much more predictable scale up for
724 // the delay. It also provides a simple/direct point to check for any
725 // safepoint requests from the VMThread
726
727 // temporarily drops SR_lock while doing wait with safepoint check
728 // (if we're a JavaThread - the WatcherThread can also call this)
729 // and increase delay with each retry
730 if (Thread::current()->is_Java_thread()) {
731 SR_lock()->wait(i * delay);
732 } else {
733 SR_lock()->wait_without_safepoint_check(i * delay);
734 }
735
736 // check the actual thread state instead of what we saved above
737 if (thread_state() != _thread_in_native_trans) {
738 // the thread has transitioned to another thread state so
739 // try all the checks (except this one) one more time.
740 do_trans_retry = true;
741 break;
742 }
743 } // end retry loop
744
745
746 }
747 } while (do_trans_retry);
748
749 *bits |= 0x00000010;
750 return false;
751 }
752
753 // Wait for an external suspend request to complete (or be cancelled).
754 // Returns true if the thread is externally suspended and false otherwise.
755 //
756 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
757 uint32_t *bits) {
758 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
759 false /* !called_by_wait */, bits);
760
761 // local flag copies to minimize SR_lock hold time
762 bool is_suspended;
763 bool pending;
764 uint32_t reset_bits;
765
766 // set a marker so is_ext_suspend_completed() knows we are the caller
767 *bits |= 0x00010000;
768
769 // We use reset_bits to reinitialize the bits value at the top of
770 // each retry loop. This allows the caller to make use of any
771 // unused bits for their own marking purposes.
772 reset_bits = *bits;
773
774 {
775 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
776 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
777 delay, bits);
778 pending = is_external_suspend();
779 }
780 // must release SR_lock to allow suspension to complete
781
782 if (!pending) {
783 // A cancelled suspend request is the only false return from
784 // is_ext_suspend_completed() that keeps us from entering the
785 // retry loop.
786 *bits |= 0x00020000;
787 return false;
788 }
789
790 if (is_suspended) {
791 *bits |= 0x00040000;
792 return true;
793 }
794
795 for (int i = 1; i <= retries; i++) {
796 *bits = reset_bits; // reinit to only track last retry
797
798 // We used to do an "os::yield_all(i)" call here with the intention
799 // that yielding would increase on each retry. However, the parameter
800 // is ignored on Linux which means the yield didn't scale up. Waiting
801 // on the SR_lock below provides a much more predictable scale up for
802 // the delay. It also provides a simple/direct point to check for any
803 // safepoint requests from the VMThread
804
805 {
806 Thread* t = Thread::current();
807 MonitorLocker ml(SR_lock(),
808 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
809 // wait with safepoint check (if we're a JavaThread - the WatcherThread
810 // can also call this) and increase delay with each retry
811 ml.wait(i * delay);
812
813 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
814 delay, bits);
815
816 // It is possible for the external suspend request to be cancelled
817 // (by a resume) before the actual suspend operation is completed.
818 // Refresh our local copy to see if we still need to wait.
819 pending = is_external_suspend();
820 }
821
822 if (!pending) {
823 // A cancelled suspend request is the only false return from
824 // is_ext_suspend_completed() that keeps us from staying in the
825 // retry loop.
826 *bits |= 0x00080000;
827 return false;
828 }
829
830 if (is_suspended) {
831 *bits |= 0x00100000;
832 return true;
833 }
834 } // end retry loop
835
836 // thread did not suspend after all our retries
837 *bits |= 0x00200000;
838 return false;
839 }
840
841 // Called from API entry points which perform stack walking. If the
842 // associated JavaThread is the current thread, then wait_for_suspend
843 // is not used. Otherwise, it determines if we should wait for the
844 // "other" thread to complete external suspension. (NOTE: in future
845 // releases the suspension mechanism should be reimplemented so this
846 // is not necessary.)
847 //
848 bool
849 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
850 if (this != JavaThread::current()) {
851 // "other" threads require special handling.
852 if (wait_for_suspend) {
853 // We are allowed to wait for the external suspend to complete
854 // so give the other thread a chance to get suspended.
855 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
856 SuspendRetryDelay, bits)) {
857 // Didn't make it so let the caller know.
858 return false;
859 }
860 }
861 // We aren't allowed to wait for the external suspend to complete
862 // so if the other thread isn't externally suspended we need to
863 // let the caller know.
864 else if (!is_ext_suspend_completed_with_lock(bits)) {
865 return false;
866 }
867 }
868
869 return true;
870 }
871
872 // GC Support
873 bool Thread::claim_par_threads_do(uintx claim_token) {
874 uintx token = _threads_do_token;
875 if (token != claim_token) {
876 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
877 if (res == token) {
878 return true;
879 }
880 guarantee(res == claim_token, "invariant");
881 }
882 return false;
883 }
884
885 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
886 if (active_handles() != NULL) {
887 active_handles()->oops_do(f);
888 }
889 // Do oop for ThreadShadow
890 f->do_oop((oop*)&_pending_exception);
891 handle_area()->oops_do(f);
892
893 // We scan thread local monitor lists here, and the remaining global
894 // monitors in ObjectSynchronizer::oops_do().
895 ObjectSynchronizer::thread_local_used_oops_do(this, f);
896 }
897
898 void Thread::metadata_handles_do(void f(Metadata*)) {
899 // Only walk the Handles in Thread.
900 if (metadata_handles() != NULL) {
901 for (int i = 0; i< metadata_handles()->length(); i++) {
902 f(metadata_handles()->at(i));
903 }
904 }
905 }
906
907 void Thread::print_on(outputStream* st, bool print_extended_info) const {
908 // get_priority assumes osthread initialized
909 if (osthread() != NULL) {
910 int os_prio;
911 if (os::get_native_priority(this, &os_prio) == OS_OK) {
912 st->print("os_prio=%d ", os_prio);
913 }
914
915 st->print("cpu=%.2fms ",
916 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
917 );
918 st->print("elapsed=%.2fs ",
919 _statistical_info.getElapsedTime() / 1000.0
920 );
921 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
922 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
923 st->print("allocated=" SIZE_FORMAT "%s ",
924 byte_size_in_proper_unit(allocated_bytes),
925 proper_unit_for_byte_size(allocated_bytes)
926 );
927 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
928 }
929
930 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
931 osthread()->print_on(st);
932 }
933 ThreadsSMRSupport::print_info_on(this, st);
934 st->print(" ");
935 debug_only(if (WizardMode) print_owned_locks_on(st);)
936 }
937
938 void Thread::print() const { print_on(tty); }
939
940 // Thread::print_on_error() is called by fatal error handler. Don't use
941 // any lock or allocate memory.
942 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
943 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
944
945 if (is_VM_thread()) { st->print("VMThread"); }
946 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
947 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
948 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
949 else { st->print("Thread"); }
950
951 if (is_Named_thread()) {
952 st->print(" \"%s\"", name());
953 }
954
955 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
956 p2i(stack_end()), p2i(stack_base()));
957
958 if (osthread()) {
959 st->print(" [id=%d]", osthread()->thread_id());
960 }
961
962 ThreadsSMRSupport::print_info_on(this, st);
963 }
964
965 void Thread::print_value_on(outputStream* st) const {
966 if (is_Named_thread()) {
967 st->print(" \"%s\" ", name());
968 }
969 st->print(INTPTR_FORMAT, p2i(this)); // print address
970 }
971
972 #ifdef ASSERT
973 void Thread::print_owned_locks_on(outputStream* st) const {
974 Mutex* cur = _owned_locks;
975 if (cur == NULL) {
976 st->print(" (no locks) ");
977 } else {
978 st->print_cr(" Locks owned:");
979 while (cur) {
980 cur->print_on(st);
981 cur = cur->next();
982 }
983 }
984 }
985
986 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
987 void Thread::check_possible_safepoint() {
988 if (!is_Java_thread()) return;
989
990 if (_no_safepoint_count > 0) {
991 print_owned_locks();
992 assert(false, "Possible safepoint reached by thread that does not allow it");
993 }
994 #ifdef CHECK_UNHANDLED_OOPS
995 // Clear unhandled oops in JavaThreads so we get a crash right away.
996 clear_unhandled_oops();
997 #endif // CHECK_UNHANDLED_OOPS
998 }
999
1000 void Thread::check_for_valid_safepoint_state() {
1001 if (!is_Java_thread()) return;
1002
1003 // Check NoSafepointVerifier, which is implied by locks taken that can be
1004 // shared with the VM thread. This makes sure that no locks with allow_vm_block
1005 // are held.
1006 check_possible_safepoint();
1007
1008 if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1009 fatal("LEAF method calling lock?");
1010 }
1011
1012 if (GCALotAtAllSafepoints) {
1013 // We could enter a safepoint here and thus have a gc
1014 InterfaceSupport::check_gc_alot();
1015 }
1016 }
1017 #endif // ASSERT
1018
1019 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1020 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1021 // used for compilation in the future. If that change is made, the need for these methods
1022 // should be revisited, and they should be removed if possible.
1023
1024 bool Thread::is_lock_owned(address adr) const {
1025 return is_in_full_stack(adr);
1026 }
1027
1028 bool Thread::set_as_starting_thread() {
1029 assert(_starting_thread == NULL, "already initialized: "
1030 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1031 // NOTE: this must be called inside the main thread.
1032 DEBUG_ONLY(_starting_thread = this;)
1033 return os::create_main_thread((JavaThread*)this);
1034 }
1035
1036 static void initialize_class(Symbol* class_name, TRAPS) {
1037 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1038 InstanceKlass::cast(klass)->initialize(CHECK);
1039 }
1040
1041
1042 // Creates the initial ThreadGroup
1043 static Handle create_initial_thread_group(TRAPS) {
1044 Handle system_instance = JavaCalls::construct_new_instance(
1045 SystemDictionary::ThreadGroup_klass(),
1046 vmSymbols::void_method_signature(),
1047 CHECK_NH);
1048 Universe::set_system_thread_group(system_instance());
1049
1050 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1051 Handle main_instance = JavaCalls::construct_new_instance(
1052 SystemDictionary::ThreadGroup_klass(),
1053 vmSymbols::threadgroup_string_void_signature(),
1054 system_instance,
1055 string,
1056 CHECK_NH);
1057 return main_instance;
1058 }
1059
1060 // Creates the initial Thread, and sets it to running.
1061 static void create_initial_thread(Handle thread_group, JavaThread* thread,
1062 TRAPS) {
1063 InstanceKlass* ik = SystemDictionary::Thread_klass();
1064 assert(ik->is_initialized(), "must be");
1065 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1066
1067 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1068 // constructor calls Thread.current(), which must be set here for the
1069 // initial thread.
1070 java_lang_Thread::set_thread(thread_oop(), thread);
1071 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1072 thread->set_threadObj(thread_oop());
1073
1074 Handle string = java_lang_String::create_from_str("main", CHECK);
1075
1076 JavaValue result(T_VOID);
1077 JavaCalls::call_special(&result, thread_oop,
1078 ik,
1079 vmSymbols::object_initializer_name(),
1080 vmSymbols::threadgroup_string_void_signature(),
1081 thread_group,
1082 string,
1083 CHECK);
1084
1085 // Set thread status to running since main thread has
1086 // been started and running.
1087 java_lang_Thread::set_thread_status(thread_oop(),
1088 java_lang_Thread::RUNNABLE);
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093 char java_runtime_vendor_version[128] = "";
1094 char java_runtime_vendor_vm_bug_url[128] = "";
1095
1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1097 static const char* get_java_runtime_name(TRAPS) {
1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1100 fieldDescriptor fd;
1101 bool found = k != NULL &&
1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1103 vmSymbols::string_signature(), &fd);
1104 if (found) {
1105 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1106 if (name_oop == NULL) {
1107 return NULL;
1108 }
1109 const char* name = java_lang_String::as_utf8_string(name_oop,
1110 java_runtime_name,
1111 sizeof(java_runtime_name));
1112 return name;
1113 } else {
1114 return NULL;
1115 }
1116 }
1117
1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1119 static const char* get_java_runtime_version(TRAPS) {
1120 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1121 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1122 fieldDescriptor fd;
1123 bool found = k != NULL &&
1124 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1125 vmSymbols::string_signature(), &fd);
1126 if (found) {
1127 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1128 if (name_oop == NULL) {
1129 return NULL;
1130 }
1131 const char* name = java_lang_String::as_utf8_string(name_oop,
1132 java_runtime_version,
1133 sizeof(java_runtime_version));
1134 return name;
1135 } else {
1136 return NULL;
1137 }
1138 }
1139
1140 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION
1141 static const char* get_java_runtime_vendor_version(TRAPS) {
1142 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1143 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1144 fieldDescriptor fd;
1145 bool found = k != NULL &&
1146 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(),
1147 vmSymbols::string_signature(), &fd);
1148 if (found) {
1149 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1150 if (name_oop == NULL) {
1151 return NULL;
1152 }
1153 const char* name = java_lang_String::as_utf8_string(name_oop,
1154 java_runtime_vendor_version,
1155 sizeof(java_runtime_vendor_version));
1156 return name;
1157 } else {
1158 return NULL;
1159 }
1160 }
1161
1162 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG
1163 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) {
1164 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1165 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1166 fieldDescriptor fd;
1167 bool found = k != NULL &&
1168 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(),
1169 vmSymbols::string_signature(), &fd);
1170 if (found) {
1171 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1172 if (name_oop == NULL) {
1173 return NULL;
1174 }
1175 const char* name = java_lang_String::as_utf8_string(name_oop,
1176 java_runtime_vendor_vm_bug_url,
1177 sizeof(java_runtime_vendor_vm_bug_url));
1178 return name;
1179 } else {
1180 return NULL;
1181 }
1182 }
1183
1184 // General purpose hook into Java code, run once when the VM is initialized.
1185 // The Java library method itself may be changed independently from the VM.
1186 static void call_postVMInitHook(TRAPS) {
1187 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1188 if (klass != NULL) {
1189 JavaValue result(T_VOID);
1190 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1191 vmSymbols::void_method_signature(),
1192 CHECK);
1193 }
1194 }
1195
1196 // Initialized by VMThread at vm_global_init
1197 static OopStorage* _thread_oop_storage = NULL;
1198
1199 oop JavaThread::threadObj() const {
1200 return _threadObj.resolve();
1201 }
1202
1203 void JavaThread::set_threadObj(oop p) {
1204 assert(_thread_oop_storage != NULL, "not yet initialized");
1205 _threadObj = OopHandle(_thread_oop_storage, p);
1206 }
1207
1208 OopStorage* JavaThread::thread_oop_storage() {
1209 assert(_thread_oop_storage != NULL, "not yet initialized");
1210 return _thread_oop_storage;
1211 }
1212
1213 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1214 bool daemon, TRAPS) {
1215 assert(thread_group.not_null(), "thread group should be specified");
1216 assert(threadObj() == NULL, "should only create Java thread object once");
1217
1218 InstanceKlass* ik = SystemDictionary::Thread_klass();
1219 assert(ik->is_initialized(), "must be");
1220 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1221
1222 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1223 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1224 // constructor calls Thread.current(), which must be set here.
1225 java_lang_Thread::set_thread(thread_oop(), this);
1226 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1227 set_threadObj(thread_oop());
1228
1229 JavaValue result(T_VOID);
1230 if (thread_name != NULL) {
1231 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1232 // Thread gets assigned specified name and null target
1233 JavaCalls::call_special(&result,
1234 thread_oop,
1235 ik,
1236 vmSymbols::object_initializer_name(),
1237 vmSymbols::threadgroup_string_void_signature(),
1238 thread_group,
1239 name,
1240 THREAD);
1241 } else {
1242 // Thread gets assigned name "Thread-nnn" and null target
1243 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1244 JavaCalls::call_special(&result,
1245 thread_oop,
1246 ik,
1247 vmSymbols::object_initializer_name(),
1248 vmSymbols::threadgroup_runnable_void_signature(),
1249 thread_group,
1250 Handle(),
1251 THREAD);
1252 }
1253
1254
1255 if (daemon) {
1256 java_lang_Thread::set_daemon(thread_oop());
1257 }
1258
1259 if (HAS_PENDING_EXCEPTION) {
1260 return;
1261 }
1262
1263 Klass* group = SystemDictionary::ThreadGroup_klass();
1264 Handle threadObj(THREAD, this->threadObj());
1265
1266 JavaCalls::call_special(&result,
1267 thread_group,
1268 group,
1269 vmSymbols::add_method_name(),
1270 vmSymbols::thread_void_signature(),
1271 threadObj, // Arg 1
1272 THREAD);
1273 }
1274
1275 // List of all NonJavaThreads and safe iteration over that list.
1276
1277 class NonJavaThread::List {
1278 public:
1279 NonJavaThread* volatile _head;
1280 SingleWriterSynchronizer _protect;
1281
1282 List() : _head(NULL), _protect() {}
1283 };
1284
1285 NonJavaThread::List NonJavaThread::_the_list;
1286
1287 NonJavaThread::Iterator::Iterator() :
1288 _protect_enter(_the_list._protect.enter()),
1289 _current(Atomic::load_acquire(&_the_list._head))
1290 {}
1291
1292 NonJavaThread::Iterator::~Iterator() {
1293 _the_list._protect.exit(_protect_enter);
1294 }
1295
1296 void NonJavaThread::Iterator::step() {
1297 assert(!end(), "precondition");
1298 _current = Atomic::load_acquire(&_current->_next);
1299 }
1300
1301 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1302 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1303 }
1304
1305 NonJavaThread::~NonJavaThread() { }
1306
1307 void NonJavaThread::add_to_the_list() {
1308 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1309 // Initialize BarrierSet-related data before adding to list.
1310 BarrierSet::barrier_set()->on_thread_attach(this);
1311 Atomic::release_store(&_next, _the_list._head);
1312 Atomic::release_store(&_the_list._head, this);
1313 }
1314
1315 void NonJavaThread::remove_from_the_list() {
1316 {
1317 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1318 // Cleanup BarrierSet-related data before removing from list.
1319 BarrierSet::barrier_set()->on_thread_detach(this);
1320 NonJavaThread* volatile* p = &_the_list._head;
1321 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1322 if (t == this) {
1323 *p = _next;
1324 break;
1325 }
1326 }
1327 }
1328 // Wait for any in-progress iterators. Concurrent synchronize is not
1329 // allowed, so do it while holding a dedicated lock. Outside and distinct
1330 // from NJTList_lock in case an iteration attempts to lock it.
1331 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1332 _the_list._protect.synchronize();
1333 _next = NULL; // Safe to drop the link now.
1334 }
1335
1336 void NonJavaThread::pre_run() {
1337 add_to_the_list();
1338
1339 // This is slightly odd in that NamedThread is a subclass, but
1340 // in fact name() is defined in Thread
1341 assert(this->name() != NULL, "thread name was not set before it was started");
1342 this->set_native_thread_name(this->name());
1343 }
1344
1345 void NonJavaThread::post_run() {
1346 JFR_ONLY(Jfr::on_thread_exit(this);)
1347 remove_from_the_list();
1348 // Ensure thread-local-storage is cleared before termination.
1349 Thread::clear_thread_current();
1350 }
1351
1352 // NamedThread -- non-JavaThread subclasses with multiple
1353 // uniquely named instances should derive from this.
1354 NamedThread::NamedThread() :
1355 NonJavaThread(),
1356 _name(NULL),
1357 _processed_thread(NULL),
1358 _gc_id(GCId::undefined())
1359 {}
1360
1361 NamedThread::~NamedThread() {
1362 FREE_C_HEAP_ARRAY(char, _name);
1363 }
1364
1365 void NamedThread::set_name(const char* format, ...) {
1366 guarantee(_name == NULL, "Only get to set name once.");
1367 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1368 va_list ap;
1369 va_start(ap, format);
1370 jio_vsnprintf(_name, max_name_len, format, ap);
1371 va_end(ap);
1372 }
1373
1374 void NamedThread::print_on(outputStream* st) const {
1375 st->print("\"%s\" ", name());
1376 Thread::print_on(st);
1377 st->cr();
1378 }
1379
1380
1381 // ======= WatcherThread ========
1382
1383 // The watcher thread exists to simulate timer interrupts. It should
1384 // be replaced by an abstraction over whatever native support for
1385 // timer interrupts exists on the platform.
1386
1387 WatcherThread* WatcherThread::_watcher_thread = NULL;
1388 bool WatcherThread::_startable = false;
1389 volatile bool WatcherThread::_should_terminate = false;
1390
1391 WatcherThread::WatcherThread() : NonJavaThread() {
1392 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1393 if (os::create_thread(this, os::watcher_thread)) {
1394 _watcher_thread = this;
1395
1396 // Set the watcher thread to the highest OS priority which should not be
1397 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1398 // is created. The only normal thread using this priority is the reference
1399 // handler thread, which runs for very short intervals only.
1400 // If the VMThread's priority is not lower than the WatcherThread profiling
1401 // will be inaccurate.
1402 os::set_priority(this, MaxPriority);
1403 if (!DisableStartThread) {
1404 os::start_thread(this);
1405 }
1406 }
1407 }
1408
1409 int WatcherThread::sleep() const {
1410 // The WatcherThread does not participate in the safepoint protocol
1411 // for the PeriodicTask_lock because it is not a JavaThread.
1412 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1413
1414 if (_should_terminate) {
1415 // check for termination before we do any housekeeping or wait
1416 return 0; // we did not sleep.
1417 }
1418
1419 // remaining will be zero if there are no tasks,
1420 // causing the WatcherThread to sleep until a task is
1421 // enrolled
1422 int remaining = PeriodicTask::time_to_wait();
1423 int time_slept = 0;
1424
1425 // we expect this to timeout - we only ever get unparked when
1426 // we should terminate or when a new task has been enrolled
1427 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1428
1429 jlong time_before_loop = os::javaTimeNanos();
1430
1431 while (true) {
1432 bool timedout = ml.wait(remaining);
1433 jlong now = os::javaTimeNanos();
1434
1435 if (remaining == 0) {
1436 // if we didn't have any tasks we could have waited for a long time
1437 // consider the time_slept zero and reset time_before_loop
1438 time_slept = 0;
1439 time_before_loop = now;
1440 } else {
1441 // need to recalculate since we might have new tasks in _tasks
1442 time_slept = (int) ((now - time_before_loop) / 1000000);
1443 }
1444
1445 // Change to task list or spurious wakeup of some kind
1446 if (timedout || _should_terminate) {
1447 break;
1448 }
1449
1450 remaining = PeriodicTask::time_to_wait();
1451 if (remaining == 0) {
1452 // Last task was just disenrolled so loop around and wait until
1453 // another task gets enrolled
1454 continue;
1455 }
1456
1457 remaining -= time_slept;
1458 if (remaining <= 0) {
1459 break;
1460 }
1461 }
1462
1463 return time_slept;
1464 }
1465
1466 void WatcherThread::run() {
1467 assert(this == watcher_thread(), "just checking");
1468
1469 this->set_active_handles(JNIHandleBlock::allocate_block());
1470 while (true) {
1471 assert(watcher_thread() == Thread::current(), "thread consistency check");
1472 assert(watcher_thread() == this, "thread consistency check");
1473
1474 // Calculate how long it'll be until the next PeriodicTask work
1475 // should be done, and sleep that amount of time.
1476 int time_waited = sleep();
1477
1478 if (VMError::is_error_reported()) {
1479 // A fatal error has happened, the error handler(VMError::report_and_die)
1480 // should abort JVM after creating an error log file. However in some
1481 // rare cases, the error handler itself might deadlock. Here periodically
1482 // check for error reporting timeouts, and if it happens, just proceed to
1483 // abort the VM.
1484
1485 // This code is in WatcherThread because WatcherThread wakes up
1486 // periodically so the fatal error handler doesn't need to do anything;
1487 // also because the WatcherThread is less likely to crash than other
1488 // threads.
1489
1490 for (;;) {
1491 // Note: we use naked sleep in this loop because we want to avoid using
1492 // any kind of VM infrastructure which may be broken at this point.
1493 if (VMError::check_timeout()) {
1494 // We hit error reporting timeout. Error reporting was interrupted and
1495 // will be wrapping things up now (closing files etc). Give it some more
1496 // time, then quit the VM.
1497 os::naked_short_sleep(200);
1498 // Print a message to stderr.
1499 fdStream err(defaultStream::output_fd());
1500 err.print_raw_cr("# [ timer expired, abort... ]");
1501 // skip atexit/vm_exit/vm_abort hooks
1502 os::die();
1503 }
1504
1505 // Wait a second, then recheck for timeout.
1506 os::naked_short_sleep(999);
1507 }
1508 }
1509
1510 if (_should_terminate) {
1511 // check for termination before posting the next tick
1512 break;
1513 }
1514
1515 PeriodicTask::real_time_tick(time_waited);
1516 }
1517
1518 // Signal that it is terminated
1519 {
1520 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1521 _watcher_thread = NULL;
1522 Terminator_lock->notify_all();
1523 }
1524 }
1525
1526 void WatcherThread::start() {
1527 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1528
1529 if (watcher_thread() == NULL && _startable) {
1530 _should_terminate = false;
1531 // Create the single instance of WatcherThread
1532 new WatcherThread();
1533 }
1534 }
1535
1536 void WatcherThread::make_startable() {
1537 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1538 _startable = true;
1539 }
1540
1541 void WatcherThread::stop() {
1542 {
1543 // Follow normal safepoint aware lock enter protocol since the
1544 // WatcherThread is stopped by another JavaThread.
1545 MutexLocker ml(PeriodicTask_lock);
1546 _should_terminate = true;
1547
1548 WatcherThread* watcher = watcher_thread();
1549 if (watcher != NULL) {
1550 // unpark the WatcherThread so it can see that it should terminate
1551 watcher->unpark();
1552 }
1553 }
1554
1555 MonitorLocker mu(Terminator_lock);
1556
1557 while (watcher_thread() != NULL) {
1558 // This wait should make safepoint checks, wait without a timeout,
1559 // and wait as a suspend-equivalent condition.
1560 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1561 }
1562 }
1563
1564 void WatcherThread::unpark() {
1565 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1566 PeriodicTask_lock->notify();
1567 }
1568
1569 void WatcherThread::print_on(outputStream* st) const {
1570 st->print("\"%s\" ", name());
1571 Thread::print_on(st);
1572 st->cr();
1573 }
1574
1575 // ======= JavaThread ========
1576
1577 #if INCLUDE_JVMCI
1578
1579 jlong* JavaThread::_jvmci_old_thread_counters;
1580
1581 bool jvmci_counters_include(JavaThread* thread) {
1582 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1583 }
1584
1585 void JavaThread::collect_counters(jlong* array, int length) {
1586 assert(length == JVMCICounterSize, "wrong value");
1587 for (int i = 0; i < length; i++) {
1588 array[i] = _jvmci_old_thread_counters[i];
1589 }
1590 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1591 if (jvmci_counters_include(tp)) {
1592 for (int i = 0; i < length; i++) {
1593 array[i] += tp->_jvmci_counters[i];
1594 }
1595 }
1596 }
1597 }
1598
1599 // Attempt to enlarge the array for per thread counters.
1600 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1601 jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
1602 if (new_counters == NULL) {
1603 return NULL;
1604 }
1605 if (old_counters == NULL) {
1606 old_counters = new_counters;
1607 memset(old_counters, 0, sizeof(jlong) * new_size);
1608 } else {
1609 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1610 new_counters[i] = old_counters[i];
1611 }
1612 if (new_size > current_size) {
1613 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1614 }
1615 FREE_C_HEAP_ARRAY(jlong, old_counters);
1616 }
1617 return new_counters;
1618 }
1619
1620 // Attempt to enlarge the array for per thread counters.
1621 bool JavaThread::resize_counters(int current_size, int new_size) {
1622 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1623 if (new_counters == NULL) {
1624 return false;
1625 } else {
1626 _jvmci_counters = new_counters;
1627 return true;
1628 }
1629 }
1630
1631 class VM_JVMCIResizeCounters : public VM_Operation {
1632 private:
1633 int _new_size;
1634 bool _failed;
1635
1636 public:
1637 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1638 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1639 bool allow_nested_vm_operations() const { return true; }
1640 void doit() {
1641 // Resize the old thread counters array
1642 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1643 if (new_counters == NULL) {
1644 _failed = true;
1645 return;
1646 } else {
1647 JavaThread::_jvmci_old_thread_counters = new_counters;
1648 }
1649
1650 // Now resize each threads array
1651 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1652 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1653 _failed = true;
1654 break;
1655 }
1656 }
1657 if (!_failed) {
1658 JVMCICounterSize = _new_size;
1659 }
1660 }
1661
1662 bool failed() { return _failed; }
1663 };
1664
1665 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1666 VM_JVMCIResizeCounters op(new_size);
1667 VMThread::execute(&op);
1668 return !op.failed();
1669 }
1670
1671 #endif // INCLUDE_JVMCI
1672
1673 // A JavaThread is a normal Java thread
1674
1675 void JavaThread::initialize() {
1676 // Initialize fields
1677
1678 set_saved_exception_pc(NULL);
1679 _anchor.clear();
1680 set_entry_point(NULL);
1681 set_jni_functions(jni_functions());
1682 set_callee_target(NULL);
1683 set_vm_result(NULL);
1684 set_vm_result_2(NULL);
1685 set_vframe_array_head(NULL);
1686 set_vframe_array_last(NULL);
1687 set_deferred_locals(NULL);
1688 set_deopt_mark(NULL);
1689 set_deopt_compiled_method(NULL);
1690 set_monitor_chunks(NULL);
1691 _on_thread_list = false;
1692 _thread_state = _thread_new;
1693 _terminated = _not_terminated;
1694 _array_for_gc = NULL;
1695 _suspend_equivalent = false;
1696 _in_deopt_handler = 0;
1697 _doing_unsafe_access = false;
1698 _stack_guard_state = stack_guard_unused;
1699 #if INCLUDE_JVMCI
1700 _pending_monitorenter = false;
1701 _pending_deoptimization = -1;
1702 _pending_failed_speculation = 0;
1703 _pending_transfer_to_interpreter = false;
1704 _in_retryable_allocation = false;
1705 _jvmci._alternate_call_target = NULL;
1706 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1707 _jvmci_counters = NULL;
1708 if (JVMCICounterSize > 0) {
1709 resize_counters(0, (int) JVMCICounterSize);
1710 }
1711 #endif // INCLUDE_JVMCI
1712 _reserved_stack_activation = NULL; // stack base not known yet
1713 set_exception_oop(oop());
1714 _exception_pc = 0;
1715 _exception_handler_pc = 0;
1716 _is_method_handle_return = 0;
1717 _jvmti_thread_state= NULL;
1718 _should_post_on_exceptions_flag = JNI_FALSE;
1719 _interp_only_mode = 0;
1720 _special_runtime_exit_condition = _no_async_condition;
1721 _pending_async_exception = NULL;
1722 _thread_stat = NULL;
1723 _thread_stat = new ThreadStatistics();
1724 _jni_active_critical = 0;
1725 _pending_jni_exception_check_fn = NULL;
1726 _do_not_unlock_if_synchronized = false;
1727 _cached_monitor_info = NULL;
1728 _parker = Parker::Allocate(this);
1729 _SleepEvent = ParkEvent::Allocate(this);
1730 // Setup safepoint state info for this thread
1731 ThreadSafepointState::create(this);
1732 _handshake.set_handshakee(this);
1733
1734 debug_only(_java_call_counter = 0);
1735
1736 // JVMTI PopFrame support
1737 _popframe_condition = popframe_inactive;
1738 _popframe_preserved_args = NULL;
1739 _popframe_preserved_args_size = 0;
1740 _frames_to_pop_failed_realloc = 0;
1741
1742 SafepointMechanism::initialize_header(this);
1743
1744 _class_to_be_initialized = NULL;
1745
1746 pd_initialize();
1747 }
1748
1749 JavaThread::JavaThread(bool is_attaching_via_jni) :
1750 Thread() {
1751 initialize();
1752 if (is_attaching_via_jni) {
1753 _jni_attach_state = _attaching_via_jni;
1754 } else {
1755 _jni_attach_state = _not_attaching_via_jni;
1756 }
1757 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1758 }
1759
1760
1761 // interrupt support
1762
1763 void JavaThread::interrupt() {
1764 debug_only(check_for_dangling_thread_pointer(this);)
1765
1766 // For Windows _interrupt_event
1767 osthread()->set_interrupted(true);
1768
1769 // For Thread.sleep
1770 _SleepEvent->unpark();
1771
1772 // For JSR166 LockSupport.park
1773 parker()->unpark();
1774
1775 // For ObjectMonitor and JvmtiRawMonitor
1776 _ParkEvent->unpark();
1777 }
1778
1779
1780 bool JavaThread::is_interrupted(bool clear_interrupted) {
1781 debug_only(check_for_dangling_thread_pointer(this);)
1782
1783 if (_threadObj.peek() == NULL) {
1784 // If there is no j.l.Thread then it is impossible to have
1785 // been interrupted. We can find NULL during VM initialization
1786 // or when a JNI thread is still in the process of attaching.
1787 // In such cases this must be the current thread.
1788 assert(this == Thread::current(), "invariant");
1789 return false;
1790 }
1791
1792 bool interrupted = java_lang_Thread::interrupted(threadObj());
1793
1794 // NOTE that since there is no "lock" around the interrupt and
1795 // is_interrupted operations, there is the possibility that the
1796 // interrupted flag will be "false" but that the
1797 // low-level events will be in the signaled state. This is
1798 // intentional. The effect of this is that Object.wait() and
1799 // LockSupport.park() will appear to have a spurious wakeup, which
1800 // is allowed and not harmful, and the possibility is so rare that
1801 // it is not worth the added complexity to add yet another lock.
1802 // For the sleep event an explicit reset is performed on entry
1803 // to JavaThread::sleep, so there is no early return. It has also been
1804 // recommended not to put the interrupted flag into the "event"
1805 // structure because it hides the issue.
1806 // Also, because there is no lock, we must only clear the interrupt
1807 // state if we are going to report that we were interrupted; otherwise
1808 // an interrupt that happens just after we read the field would be lost.
1809 if (interrupted && clear_interrupted) {
1810 assert(this == Thread::current(), "only the current thread can clear");
1811 java_lang_Thread::set_interrupted(threadObj(), false);
1812 osthread()->set_interrupted(false);
1813 }
1814
1815 return interrupted;
1816 }
1817
1818 bool JavaThread::reguard_stack(address cur_sp) {
1819 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1820 && _stack_guard_state != stack_guard_reserved_disabled) {
1821 return true; // Stack already guarded or guard pages not needed.
1822 }
1823
1824 if (register_stack_overflow()) {
1825 // For those architectures which have separate register and
1826 // memory stacks, we must check the register stack to see if
1827 // it has overflowed.
1828 return false;
1829 }
1830
1831 // Java code never executes within the yellow zone: the latter is only
1832 // there to provoke an exception during stack banging. If java code
1833 // is executing there, either StackShadowPages should be larger, or
1834 // some exception code in c1, c2 or the interpreter isn't unwinding
1835 // when it should.
1836 guarantee(cur_sp > stack_reserved_zone_base(),
1837 "not enough space to reguard - increase StackShadowPages");
1838 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1839 enable_stack_yellow_reserved_zone();
1840 if (reserved_stack_activation() != stack_base()) {
1841 set_reserved_stack_activation(stack_base());
1842 }
1843 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1844 set_reserved_stack_activation(stack_base());
1845 enable_stack_reserved_zone();
1846 }
1847 return true;
1848 }
1849
1850 bool JavaThread::reguard_stack(void) {
1851 return reguard_stack(os::current_stack_pointer());
1852 }
1853
1854 void JavaThread::block_if_vm_exited() {
1855 if (_terminated == _vm_exited) {
1856 // _vm_exited is set at safepoint, and Threads_lock is never released
1857 // we will block here forever.
1858 // Here we can be doing a jump from a safe state to an unsafe state without
1859 // proper transition, but it happens after the final safepoint has begun.
1860 set_thread_state(_thread_in_vm);
1861 Threads_lock->lock();
1862 ShouldNotReachHere();
1863 }
1864 }
1865
1866
1867 // Remove this ifdef when C1 is ported to the compiler interface.
1868 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1869 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1870
1871 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1872 Thread() {
1873 initialize();
1874 _jni_attach_state = _not_attaching_via_jni;
1875 set_entry_point(entry_point);
1876 // Create the native thread itself.
1877 // %note runtime_23
1878 os::ThreadType thr_type = os::java_thread;
1879 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1880 os::java_thread;
1881 os::create_thread(this, thr_type, stack_sz);
1882 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1883 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1884 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1885 // the exception consists of creating the exception object & initializing it, initialization
1886 // will leave the VM via a JavaCall and then all locks must be unlocked).
1887 //
1888 // The thread is still suspended when we reach here. Thread must be explicit started
1889 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1890 // by calling Threads:add. The reason why this is not done here, is because the thread
1891 // object must be fully initialized (take a look at JVM_Start)
1892 }
1893
1894 JavaThread::~JavaThread() {
1895
1896 // Ask ServiceThread to release the threadObj OopHandle
1897 ServiceThread::add_oop_handle_release(_threadObj);
1898
1899 // JSR166 -- return the parker to the free list
1900 Parker::Release(_parker);
1901 _parker = NULL;
1902
1903 // Return the sleep event to the free list
1904 ParkEvent::Release(_SleepEvent);
1905 _SleepEvent = NULL;
1906
1907 // Free any remaining previous UnrollBlock
1908 vframeArray* old_array = vframe_array_last();
1909
1910 if (old_array != NULL) {
1911 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1912 old_array->set_unroll_block(NULL);
1913 delete old_info;
1914 delete old_array;
1915 }
1916
1917 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1918 if (deferred != NULL) {
1919 // This can only happen if thread is destroyed before deoptimization occurs.
1920 assert(deferred->length() != 0, "empty array!");
1921 do {
1922 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1923 deferred->remove_at(0);
1924 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1925 delete dlv;
1926 } while (deferred->length() != 0);
1927 delete deferred;
1928 }
1929
1930 // All Java related clean up happens in exit
1931 ThreadSafepointState::destroy(this);
1932 if (_thread_stat != NULL) delete _thread_stat;
1933
1934 #if INCLUDE_JVMCI
1935 if (JVMCICounterSize > 0) {
1936 if (jvmci_counters_include(this)) {
1937 for (int i = 0; i < JVMCICounterSize; i++) {
1938 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1939 }
1940 }
1941 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1942 }
1943 #endif // INCLUDE_JVMCI
1944 }
1945
1946
1947 // First JavaThread specific code executed by a new Java thread.
1948 void JavaThread::pre_run() {
1949 // empty - see comments in run()
1950 }
1951
1952 // The main routine called by a new Java thread. This isn't overridden
1953 // by subclasses, instead different subclasses define a different "entry_point"
1954 // which defines the actual logic for that kind of thread.
1955 void JavaThread::run() {
1956 // initialize thread-local alloc buffer related fields
1957 this->initialize_tlab();
1958
1959 // Used to test validity of stack trace backs.
1960 // This can't be moved into pre_run() else we invalidate
1961 // the requirement that thread_main_inner is lower on
1962 // the stack. Consequently all the initialization logic
1963 // stays here in run() rather than pre_run().
1964 this->record_base_of_stack_pointer();
1965
1966 this->create_stack_guard_pages();
1967
1968 this->cache_global_variables();
1969
1970 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1971 // in the VM. Change thread state from _thread_new to _thread_in_vm
1972 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1973 // Before a thread is on the threads list it is always safe, so after leaving the
1974 // _thread_new we should emit a instruction barrier. The distance to modified code
1975 // from here is probably far enough, but this is consistent and safe.
1976 OrderAccess::cross_modify_fence();
1977
1978 assert(JavaThread::current() == this, "sanity check");
1979 assert(!Thread::current()->owns_locks(), "sanity check");
1980
1981 DTRACE_THREAD_PROBE(start, this);
1982
1983 // This operation might block. We call that after all safepoint checks for a new thread has
1984 // been completed.
1985 this->set_active_handles(JNIHandleBlock::allocate_block());
1986
1987 if (JvmtiExport::should_post_thread_life()) {
1988 JvmtiExport::post_thread_start(this);
1989
1990 }
1991
1992 // We call another function to do the rest so we are sure that the stack addresses used
1993 // from there will be lower than the stack base just computed.
1994 thread_main_inner();
1995 }
1996
1997 void JavaThread::thread_main_inner() {
1998 assert(JavaThread::current() == this, "sanity check");
1999 assert(_threadObj.peek() != NULL, "just checking");
2000
2001 // Execute thread entry point unless this thread has a pending exception
2002 // or has been stopped before starting.
2003 // Note: Due to JVM_StopThread we can have pending exceptions already!
2004 if (!this->has_pending_exception() &&
2005 !java_lang_Thread::is_stillborn(this->threadObj())) {
2006 {
2007 ResourceMark rm(this);
2008 this->set_native_thread_name(this->get_thread_name());
2009 }
2010 HandleMark hm(this);
2011 this->entry_point()(this, this);
2012 }
2013
2014 DTRACE_THREAD_PROBE(stop, this);
2015
2016 // Cleanup is handled in post_run()
2017 }
2018
2019 // Shared teardown for all JavaThreads
2020 void JavaThread::post_run() {
2021 this->exit(false);
2022 // Defer deletion to here to ensure 'this' is still referenceable in call_run
2023 // for any shared tear-down.
2024 this->smr_delete();
2025 }
2026
2027 static void ensure_join(JavaThread* thread) {
2028 // We do not need to grab the Threads_lock, since we are operating on ourself.
2029 Handle threadObj(thread, thread->threadObj());
2030 assert(threadObj.not_null(), "java thread object must exist");
2031 ObjectLocker lock(threadObj, thread);
2032 // Ignore pending exception (ThreadDeath), since we are exiting anyway
2033 thread->clear_pending_exception();
2034 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
2035 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
2036 // Clear the native thread instance - this makes isAlive return false and allows the join()
2037 // to complete once we've done the notify_all below
2038 java_lang_Thread::set_thread(threadObj(), NULL);
2039 lock.notify_all(thread);
2040 // Ignore pending exception (ThreadDeath), since we are exiting anyway
2041 thread->clear_pending_exception();
2042 }
2043
2044 static bool is_daemon(oop threadObj) {
2045 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
2046 }
2047
2048 // For any new cleanup additions, please check to see if they need to be applied to
2049 // cleanup_failed_attach_current_thread as well.
2050 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2051 assert(this == JavaThread::current(), "thread consistency check");
2052
2053 elapsedTimer _timer_exit_phase1;
2054 elapsedTimer _timer_exit_phase2;
2055 elapsedTimer _timer_exit_phase3;
2056 elapsedTimer _timer_exit_phase4;
2057
2058 if (log_is_enabled(Debug, os, thread, timer)) {
2059 _timer_exit_phase1.start();
2060 }
2061
2062 HandleMark hm(this);
2063 Handle uncaught_exception(this, this->pending_exception());
2064 this->clear_pending_exception();
2065 Handle threadObj(this, this->threadObj());
2066 assert(threadObj.not_null(), "Java thread object should be created");
2067
2068 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2069 {
2070 EXCEPTION_MARK;
2071
2072 CLEAR_PENDING_EXCEPTION;
2073 }
2074 if (!destroy_vm) {
2075 if (uncaught_exception.not_null()) {
2076 EXCEPTION_MARK;
2077 // Call method Thread.dispatchUncaughtException().
2078 Klass* thread_klass = SystemDictionary::Thread_klass();
2079 JavaValue result(T_VOID);
2080 JavaCalls::call_virtual(&result,
2081 threadObj, thread_klass,
2082 vmSymbols::dispatchUncaughtException_name(),
2083 vmSymbols::throwable_void_signature(),
2084 uncaught_exception,
2085 THREAD);
2086 if (HAS_PENDING_EXCEPTION) {
2087 ResourceMark rm(this);
2088 jio_fprintf(defaultStream::error_stream(),
2089 "\nException: %s thrown from the UncaughtExceptionHandler"
2090 " in thread \"%s\"\n",
2091 pending_exception()->klass()->external_name(),
2092 get_thread_name());
2093 CLEAR_PENDING_EXCEPTION;
2094 }
2095 }
2096
2097 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2098 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2099 // is deprecated anyhow.
2100 if (!is_Compiler_thread()) {
2101 int count = 3;
2102 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2103 EXCEPTION_MARK;
2104 JavaValue result(T_VOID);
2105 Klass* thread_klass = SystemDictionary::Thread_klass();
2106 JavaCalls::call_virtual(&result,
2107 threadObj, thread_klass,
2108 vmSymbols::exit_method_name(),
2109 vmSymbols::void_method_signature(),
2110 THREAD);
2111 CLEAR_PENDING_EXCEPTION;
2112 }
2113 }
2114 // notify JVMTI
2115 if (JvmtiExport::should_post_thread_life()) {
2116 JvmtiExport::post_thread_end(this);
2117 }
2118
2119 // We have notified the agents that we are exiting, before we go on,
2120 // we must check for a pending external suspend request and honor it
2121 // in order to not surprise the thread that made the suspend request.
2122 while (true) {
2123 {
2124 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2125 if (!is_external_suspend()) {
2126 set_terminated(_thread_exiting);
2127 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2128 break;
2129 }
2130 // Implied else:
2131 // Things get a little tricky here. We have a pending external
2132 // suspend request, but we are holding the SR_lock so we
2133 // can't just self-suspend. So we temporarily drop the lock
2134 // and then self-suspend.
2135 }
2136
2137 ThreadBlockInVM tbivm(this);
2138 java_suspend_self();
2139
2140 // We're done with this suspend request, but we have to loop around
2141 // and check again. Eventually we will get SR_lock without a pending
2142 // external suspend request and will be able to mark ourselves as
2143 // exiting.
2144 }
2145 // no more external suspends are allowed at this point
2146 } else {
2147 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2148 // before_exit() has already posted JVMTI THREAD_END events
2149 }
2150
2151 if (log_is_enabled(Debug, os, thread, timer)) {
2152 _timer_exit_phase1.stop();
2153 _timer_exit_phase2.start();
2154 }
2155
2156 // Capture daemon status before the thread is marked as terminated.
2157 bool daemon = is_daemon(threadObj());
2158
2159 // Notify waiters on thread object. This has to be done after exit() is called
2160 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2161 // group should have the destroyed bit set before waiters are notified).
2162 ensure_join(this);
2163 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2164
2165 if (log_is_enabled(Debug, os, thread, timer)) {
2166 _timer_exit_phase2.stop();
2167 _timer_exit_phase3.start();
2168 }
2169 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2170 // held by this thread must be released. The spec does not distinguish
2171 // between JNI-acquired and regular Java monitors. We can only see
2172 // regular Java monitors here if monitor enter-exit matching is broken.
2173 //
2174 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2175 // ObjectSynchronizer::release_monitors_owned_by_thread().
2176 if (exit_type == jni_detach) {
2177 // Sanity check even though JNI DetachCurrentThread() would have
2178 // returned JNI_ERR if there was a Java frame. JavaThread exit
2179 // should be done executing Java code by the time we get here.
2180 assert(!this->has_last_Java_frame(),
2181 "should not have a Java frame when detaching or exiting");
2182 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2183 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2184 }
2185
2186 // These things needs to be done while we are still a Java Thread. Make sure that thread
2187 // is in a consistent state, in case GC happens
2188 JFR_ONLY(Jfr::on_thread_exit(this);)
2189
2190 if (active_handles() != NULL) {
2191 JNIHandleBlock* block = active_handles();
2192 set_active_handles(NULL);
2193 JNIHandleBlock::release_block(block);
2194 }
2195
2196 if (free_handle_block() != NULL) {
2197 JNIHandleBlock* block = free_handle_block();
2198 set_free_handle_block(NULL);
2199 JNIHandleBlock::release_block(block);
2200 }
2201
2202 // These have to be removed while this is still a valid thread.
2203 remove_stack_guard_pages();
2204
2205 if (UseTLAB) {
2206 tlab().retire();
2207 }
2208
2209 if (JvmtiEnv::environments_might_exist()) {
2210 JvmtiExport::cleanup_thread(this);
2211 }
2212
2213 // We need to cache the thread name for logging purposes below as once
2214 // we have called on_thread_detach this thread must not access any oops.
2215 char* thread_name = NULL;
2216 if (log_is_enabled(Debug, os, thread, timer)) {
2217 ResourceMark rm(this);
2218 thread_name = os::strdup(get_thread_name());
2219 }
2220
2221 // We must flush any deferred card marks and other various GC barrier
2222 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2223 // before removing a thread from the list of active threads.
2224 BarrierSet::barrier_set()->on_thread_detach(this);
2225
2226 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2227 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2228 os::current_thread_id());
2229
2230 if (log_is_enabled(Debug, os, thread, timer)) {
2231 _timer_exit_phase3.stop();
2232 _timer_exit_phase4.start();
2233 }
2234 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2235 Threads::remove(this, daemon);
2236
2237 if (log_is_enabled(Debug, os, thread, timer)) {
2238 _timer_exit_phase4.stop();
2239 log_debug(os, thread, timer)("name='%s'"
2240 ", exit-phase1=" JLONG_FORMAT
2241 ", exit-phase2=" JLONG_FORMAT
2242 ", exit-phase3=" JLONG_FORMAT
2243 ", exit-phase4=" JLONG_FORMAT,
2244 thread_name,
2245 _timer_exit_phase1.milliseconds(),
2246 _timer_exit_phase2.milliseconds(),
2247 _timer_exit_phase3.milliseconds(),
2248 _timer_exit_phase4.milliseconds());
2249 os::free(thread_name);
2250 }
2251 }
2252
2253 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2254 if (active_handles() != NULL) {
2255 JNIHandleBlock* block = active_handles();
2256 set_active_handles(NULL);
2257 JNIHandleBlock::release_block(block);
2258 }
2259
2260 if (free_handle_block() != NULL) {
2261 JNIHandleBlock* block = free_handle_block();
2262 set_free_handle_block(NULL);
2263 JNIHandleBlock::release_block(block);
2264 }
2265
2266 // These have to be removed while this is still a valid thread.
2267 remove_stack_guard_pages();
2268
2269 if (UseTLAB) {
2270 tlab().retire();
2271 }
2272
2273 BarrierSet::barrier_set()->on_thread_detach(this);
2274
2275 Threads::remove(this, is_daemon);
2276 this->smr_delete();
2277 }
2278
2279 JavaThread* JavaThread::active() {
2280 Thread* thread = Thread::current();
2281 if (thread->is_Java_thread()) {
2282 return (JavaThread*) thread;
2283 } else {
2284 assert(thread->is_VM_thread(), "this must be a vm thread");
2285 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2286 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2287 assert(ret->is_Java_thread(), "must be a Java thread");
2288 return ret;
2289 }
2290 }
2291
2292 bool JavaThread::is_lock_owned(address adr) const {
2293 if (Thread::is_lock_owned(adr)) return true;
2294
2295 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2296 if (chunk->contains(adr)) return true;
2297 }
2298
2299 return false;
2300 }
2301
2302 oop JavaThread::exception_oop() const {
2303 return Atomic::load(&_exception_oop);
2304 }
2305
2306 void JavaThread::set_exception_oop(oop o) {
2307 Atomic::store(&_exception_oop, o);
2308 }
2309
2310 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2311 chunk->set_next(monitor_chunks());
2312 set_monitor_chunks(chunk);
2313 }
2314
2315 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2316 guarantee(monitor_chunks() != NULL, "must be non empty");
2317 if (monitor_chunks() == chunk) {
2318 set_monitor_chunks(chunk->next());
2319 } else {
2320 MonitorChunk* prev = monitor_chunks();
2321 while (prev->next() != chunk) prev = prev->next();
2322 prev->set_next(chunk->next());
2323 }
2324 }
2325
2326 // JVM support.
2327
2328 // Note: this function shouldn't block if it's called in
2329 // _thread_in_native_trans state (such as from
2330 // check_special_condition_for_native_trans()).
2331 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2332 // May be we are at method entry and requires to save do not unlock flag.
2333 UnlockFlagSaver fs(this);
2334 if (has_last_Java_frame() && has_async_condition()) {
2335 // If we are at a polling page safepoint (not a poll return)
2336 // then we must defer async exception because live registers
2337 // will be clobbered by the exception path. Poll return is
2338 // ok because the call we a returning from already collides
2339 // with exception handling registers and so there is no issue.
2340 // (The exception handling path kills call result registers but
2341 // this is ok since the exception kills the result anyway).
2342
2343 if (is_at_poll_safepoint()) {
2344 // if the code we are returning to has deoptimized we must defer
2345 // the exception otherwise live registers get clobbered on the
2346 // exception path before deoptimization is able to retrieve them.
2347 //
2348 RegisterMap map(this, false);
2349 frame caller_fr = last_frame().sender(&map);
2350 assert(caller_fr.is_compiled_frame(), "what?");
2351 if (caller_fr.is_deoptimized_frame()) {
2352 log_info(exceptions)("deferred async exception at compiled safepoint");
2353 return;
2354 }
2355 }
2356 }
2357
2358 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2359 if (condition == _no_async_condition) {
2360 // Conditions have changed since has_special_runtime_exit_condition()
2361 // was called:
2362 // - if we were here only because of an external suspend request,
2363 // then that was taken care of above (or cancelled) so we are done
2364 // - if we were here because of another async request, then it has
2365 // been cleared between the has_special_runtime_exit_condition()
2366 // and now so again we are done
2367 return;
2368 }
2369
2370 // Check for pending async. exception
2371 if (_pending_async_exception != NULL) {
2372 // Only overwrite an already pending exception, if it is not a threadDeath.
2373 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2374
2375 // We cannot call Exceptions::_throw(...) here because we cannot block
2376 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2377
2378 LogTarget(Info, exceptions) lt;
2379 if (lt.is_enabled()) {
2380 ResourceMark rm;
2381 LogStream ls(lt);
2382 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2383 if (has_last_Java_frame()) {
2384 frame f = last_frame();
2385 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2386 }
2387 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2388 }
2389 _pending_async_exception = NULL;
2390 clear_has_async_exception();
2391 }
2392 }
2393
2394 if (check_unsafe_error &&
2395 condition == _async_unsafe_access_error && !has_pending_exception()) {
2396 condition = _no_async_condition; // done
2397 switch (thread_state()) {
2398 case _thread_in_vm: {
2399 JavaThread* THREAD = this;
2400 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2401 }
2402 case _thread_in_native: {
2403 ThreadInVMfromNative tiv(this);
2404 JavaThread* THREAD = this;
2405 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2406 }
2407 case _thread_in_Java: {
2408 ThreadInVMfromJava tiv(this);
2409 JavaThread* THREAD = this;
2410 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2411 }
2412 default:
2413 ShouldNotReachHere();
2414 }
2415 }
2416
2417 assert(condition == _no_async_condition || has_pending_exception() ||
2418 (!check_unsafe_error && condition == _async_unsafe_access_error),
2419 "must have handled the async condition, if no exception");
2420 }
2421
2422 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2423
2424 // Check for pending external suspend.
2425 if (is_external_suspend_with_lock()) {
2426 frame_anchor()->make_walkable(this);
2427 java_suspend_self_with_safepoint_check();
2428 }
2429
2430 // We might be here for reasons in addition to the self-suspend request
2431 // so check for other async requests.
2432 if (check_asyncs) {
2433 check_and_handle_async_exceptions();
2434 }
2435
2436 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2437 }
2438
2439 void JavaThread::send_thread_stop(oop java_throwable) {
2440 ResourceMark rm;
2441 assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread");
2442
2443 // Do not throw asynchronous exceptions against the compiler thread
2444 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2445 if (!can_call_java()) return;
2446
2447 {
2448 // Actually throw the Throwable against the target Thread - however
2449 // only if there is no thread death exception installed already.
2450 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2451 // If the topmost frame is a runtime stub, then we are calling into
2452 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2453 // must deoptimize the caller before continuing, as the compiled exception handler table
2454 // may not be valid
2455 if (has_last_Java_frame()) {
2456 frame f = last_frame();
2457 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2458 RegisterMap reg_map(this, false);
2459 frame compiled_frame = f.sender(®_map);
2460 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2461 Deoptimization::deoptimize(this, compiled_frame);
2462 }
2463 }
2464 }
2465
2466 // Set async. pending exception in thread.
2467 set_pending_async_exception(java_throwable);
2468
2469 if (log_is_enabled(Info, exceptions)) {
2470 ResourceMark rm;
2471 log_info(exceptions)("Pending Async. exception installed of type: %s",
2472 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2473 }
2474 // for AbortVMOnException flag
2475 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2476 }
2477 }
2478
2479
2480 // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2481 java_lang_Thread::set_interrupted(threadObj(), true);
2482 this->interrupt();
2483 }
2484
2485 // External suspension mechanism.
2486 //
2487 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2488 // to any VM_locks and it is at a transition
2489 // Self-suspension will happen on the transition out of the vm.
2490 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2491 //
2492 // Guarantees on return:
2493 // + Target thread will not execute any new bytecode (that's why we need to
2494 // force a safepoint)
2495 // + Target thread will not enter any new monitors
2496 //
2497 void JavaThread::java_suspend() {
2498 ThreadsListHandle tlh;
2499 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2500 return;
2501 }
2502
2503 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2504 if (!is_external_suspend()) {
2505 // a racing resume has cancelled us; bail out now
2506 return;
2507 }
2508
2509 // suspend is done
2510 uint32_t debug_bits = 0;
2511 // Warning: is_ext_suspend_completed() may temporarily drop the
2512 // SR_lock to allow the thread to reach a stable thread state if
2513 // it is currently in a transient thread state.
2514 if (is_ext_suspend_completed(false /* !called_by_wait */,
2515 SuspendRetryDelay, &debug_bits)) {
2516 return;
2517 }
2518 }
2519
2520 if (Thread::current() == this) {
2521 // Safely self-suspend.
2522 // If we don't do this explicitly it will implicitly happen
2523 // before we transition back to Java, and on some other thread-state
2524 // transition paths, but not as we exit a JVM TI SuspendThread call.
2525 // As SuspendThread(current) must not return (until resumed) we must
2526 // self-suspend here.
2527 ThreadBlockInVM tbivm(this);
2528 java_suspend_self();
2529 } else {
2530 VM_ThreadSuspend vm_suspend;
2531 VMThread::execute(&vm_suspend);
2532 }
2533 }
2534
2535 // Part II of external suspension.
2536 // A JavaThread self suspends when it detects a pending external suspend
2537 // request. This is usually on transitions. It is also done in places
2538 // where continuing to the next transition would surprise the caller,
2539 // e.g., monitor entry.
2540 //
2541 // Returns the number of times that the thread self-suspended.
2542 //
2543 // Note: DO NOT call java_suspend_self() when you just want to block current
2544 // thread. java_suspend_self() is the second stage of cooperative
2545 // suspension for external suspend requests and should only be used
2546 // to complete an external suspend request.
2547 //
2548 int JavaThread::java_suspend_self() {
2549 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2550 int ret = 0;
2551
2552 // we are in the process of exiting so don't suspend
2553 if (is_exiting()) {
2554 clear_external_suspend();
2555 return ret;
2556 }
2557
2558 assert(_anchor.walkable() ||
2559 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2560 "must have walkable stack");
2561
2562 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2563
2564 assert(!this->is_ext_suspended(),
2565 "a thread trying to self-suspend should not already be suspended");
2566
2567 if (this->is_suspend_equivalent()) {
2568 // If we are self-suspending as a result of the lifting of a
2569 // suspend equivalent condition, then the suspend_equivalent
2570 // flag is not cleared until we set the ext_suspended flag so
2571 // that wait_for_ext_suspend_completion() returns consistent
2572 // results.
2573 this->clear_suspend_equivalent();
2574 }
2575
2576 // A racing resume may have cancelled us before we grabbed SR_lock
2577 // above. Or another external suspend request could be waiting for us
2578 // by the time we return from SR_lock()->wait(). The thread
2579 // that requested the suspension may already be trying to walk our
2580 // stack and if we return now, we can change the stack out from under
2581 // it. This would be a "bad thing (TM)" and cause the stack walker
2582 // to crash. We stay self-suspended until there are no more pending
2583 // external suspend requests.
2584 while (is_external_suspend()) {
2585 ret++;
2586 this->set_ext_suspended();
2587
2588 // _ext_suspended flag is cleared by java_resume()
2589 while (is_ext_suspended()) {
2590 ml.wait();
2591 }
2592 }
2593 return ret;
2594 }
2595
2596 // Helper routine to set up the correct thread state before calling java_suspend_self.
2597 // This is called when regular thread-state transition helpers can't be used because
2598 // we can be in various states, in particular _thread_in_native_trans.
2599 // Because this thread is external suspended the safepoint code will count it as at
2600 // a safepoint, regardless of what its actual current thread-state is. But
2601 // is_ext_suspend_completed() may be waiting to see a thread transition from
2602 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2603 // to _thread_blocked. The problem with setting thread state directly is that a
2604 // safepoint could happen just after java_suspend_self() returns after being resumed,
2605 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2606 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2607 // However, not all initial-states are allowed when performing a safepoint check, as we
2608 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2609 // only _thread_in_native is possible when executing this code (based on our two callers).
2610 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2611 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2612 // and so we don't need the explicit safepoint check.
2613
2614 void JavaThread::java_suspend_self_with_safepoint_check() {
2615 assert(this == Thread::current(), "invariant");
2616 JavaThreadState state = thread_state();
2617 set_thread_state(_thread_blocked);
2618 java_suspend_self();
2619 set_thread_state_fence(state);
2620 // Since we are not using a regular thread-state transition helper here,
2621 // we must manually emit the instruction barrier after leaving a safe state.
2622 OrderAccess::cross_modify_fence();
2623 if (state != _thread_in_native) {
2624 SafepointMechanism::block_if_requested(this);
2625 }
2626 }
2627
2628 #ifdef ASSERT
2629 // Verify the JavaThread has not yet been published in the Threads::list, and
2630 // hence doesn't need protection from concurrent access at this stage.
2631 void JavaThread::verify_not_published() {
2632 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2633 // since an unpublished JavaThread doesn't participate in the
2634 // Thread-SMR protocol for keeping a ThreadsList alive.
2635 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2636 }
2637 #endif
2638
2639 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2640 // progress or when _suspend_flags is non-zero.
2641 // Current thread needs to self-suspend if there is a suspend request and/or
2642 // block if a safepoint is in progress.
2643 // Async exception ISN'T checked.
2644 // Note only the ThreadInVMfromNative transition can call this function
2645 // directly and when thread state is _thread_in_native_trans
2646 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2647 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2648
2649 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2650
2651 if (thread->is_external_suspend()) {
2652 thread->java_suspend_self_with_safepoint_check();
2653 } else {
2654 SafepointMechanism::block_if_requested(thread);
2655 }
2656
2657 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2658 }
2659
2660 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2661 // progress or when _suspend_flags is non-zero.
2662 // Current thread needs to self-suspend if there is a suspend request and/or
2663 // block if a safepoint is in progress.
2664 // Also check for pending async exception (not including unsafe access error).
2665 // Note only the native==>VM/Java barriers can call this function and when
2666 // thread state is _thread_in_native_trans.
2667 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2668 check_safepoint_and_suspend_for_native_trans(thread);
2669
2670 if (thread->has_async_exception()) {
2671 // We are in _thread_in_native_trans state, don't handle unsafe
2672 // access error since that may block.
2673 thread->check_and_handle_async_exceptions(false);
2674 }
2675 }
2676
2677 // This is a variant of the normal
2678 // check_special_condition_for_native_trans with slightly different
2679 // semantics for use by critical native wrappers. It does all the
2680 // normal checks but also performs the transition back into
2681 // thread_in_Java state. This is required so that critical natives
2682 // can potentially block and perform a GC if they are the last thread
2683 // exiting the GCLocker.
2684 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2685 check_special_condition_for_native_trans(thread);
2686
2687 // Finish the transition
2688 thread->set_thread_state(_thread_in_Java);
2689
2690 if (thread->do_critical_native_unlock()) {
2691 ThreadInVMfromJavaNoAsyncException tiv(thread);
2692 GCLocker::unlock_critical(thread);
2693 thread->clear_critical_native_unlock();
2694 }
2695 }
2696
2697 // We need to guarantee the Threads_lock here, since resumes are not
2698 // allowed during safepoint synchronization
2699 // Can only resume from an external suspension
2700 void JavaThread::java_resume() {
2701 assert_locked_or_safepoint(Threads_lock);
2702
2703 // Sanity check: thread is gone, has started exiting or the thread
2704 // was not externally suspended.
2705 ThreadsListHandle tlh;
2706 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2707 return;
2708 }
2709
2710 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2711
2712 clear_external_suspend();
2713
2714 if (is_ext_suspended()) {
2715 clear_ext_suspended();
2716 SR_lock()->notify_all();
2717 }
2718 }
2719
2720 size_t JavaThread::_stack_red_zone_size = 0;
2721 size_t JavaThread::_stack_yellow_zone_size = 0;
2722 size_t JavaThread::_stack_reserved_zone_size = 0;
2723 size_t JavaThread::_stack_shadow_zone_size = 0;
2724
2725 void JavaThread::create_stack_guard_pages() {
2726 if (!os::uses_stack_guard_pages() ||
2727 _stack_guard_state != stack_guard_unused ||
2728 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2729 log_info(os, thread)("Stack guard page creation for thread "
2730 UINTX_FORMAT " disabled", os::current_thread_id());
2731 return;
2732 }
2733 address low_addr = stack_end();
2734 size_t len = stack_guard_zone_size();
2735
2736 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2737 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2738
2739 int must_commit = os::must_commit_stack_guard_pages();
2740 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2741
2742 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2743 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2744 return;
2745 }
2746
2747 if (os::guard_memory((char *) low_addr, len)) {
2748 _stack_guard_state = stack_guard_enabled;
2749 } else {
2750 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2751 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2752 if (os::uncommit_memory((char *) low_addr, len)) {
2753 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2754 }
2755 return;
2756 }
2757
2758 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2759 PTR_FORMAT "-" PTR_FORMAT ".",
2760 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2761 }
2762
2763 void JavaThread::remove_stack_guard_pages() {
2764 assert(Thread::current() == this, "from different thread");
2765 if (_stack_guard_state == stack_guard_unused) return;
2766 address low_addr = stack_end();
2767 size_t len = stack_guard_zone_size();
2768
2769 if (os::must_commit_stack_guard_pages()) {
2770 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2771 _stack_guard_state = stack_guard_unused;
2772 } else {
2773 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2774 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2775 return;
2776 }
2777 } else {
2778 if (_stack_guard_state == stack_guard_unused) return;
2779 if (os::unguard_memory((char *) low_addr, len)) {
2780 _stack_guard_state = stack_guard_unused;
2781 } else {
2782 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2783 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2784 return;
2785 }
2786 }
2787
2788 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2789 PTR_FORMAT "-" PTR_FORMAT ".",
2790 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2791 }
2792
2793 void JavaThread::enable_stack_reserved_zone() {
2794 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2795
2796 // The base notation is from the stack's point of view, growing downward.
2797 // We need to adjust it to work correctly with guard_memory()
2798 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2799
2800 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2801 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2802
2803 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2804 _stack_guard_state = stack_guard_enabled;
2805 } else {
2806 warning("Attempt to guard stack reserved zone failed.");
2807 }
2808 enable_register_stack_guard();
2809 }
2810
2811 void JavaThread::disable_stack_reserved_zone() {
2812 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2813
2814 // Simply return if called for a thread that does not use guard pages.
2815 if (_stack_guard_state != stack_guard_enabled) return;
2816
2817 // The base notation is from the stack's point of view, growing downward.
2818 // We need to adjust it to work correctly with guard_memory()
2819 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2820
2821 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2822 _stack_guard_state = stack_guard_reserved_disabled;
2823 } else {
2824 warning("Attempt to unguard stack reserved zone failed.");
2825 }
2826 disable_register_stack_guard();
2827 }
2828
2829 void JavaThread::enable_stack_yellow_reserved_zone() {
2830 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2831 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2832
2833 // The base notation is from the stacks point of view, growing downward.
2834 // We need to adjust it to work correctly with guard_memory()
2835 address base = stack_red_zone_base();
2836
2837 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2838 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2839
2840 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2841 _stack_guard_state = stack_guard_enabled;
2842 } else {
2843 warning("Attempt to guard stack yellow zone failed.");
2844 }
2845 enable_register_stack_guard();
2846 }
2847
2848 void JavaThread::disable_stack_yellow_reserved_zone() {
2849 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2850 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2851
2852 // Simply return if called for a thread that does not use guard pages.
2853 if (_stack_guard_state == stack_guard_unused) return;
2854
2855 // The base notation is from the stacks point of view, growing downward.
2856 // We need to adjust it to work correctly with guard_memory()
2857 address base = stack_red_zone_base();
2858
2859 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2860 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2861 } else {
2862 warning("Attempt to unguard stack yellow zone failed.");
2863 }
2864 disable_register_stack_guard();
2865 }
2866
2867 void JavaThread::enable_stack_red_zone() {
2868 // The base notation is from the stacks point of view, growing downward.
2869 // We need to adjust it to work correctly with guard_memory()
2870 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2871 address base = stack_red_zone_base() - stack_red_zone_size();
2872
2873 guarantee(base < stack_base(), "Error calculating stack red zone");
2874 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2875
2876 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2877 warning("Attempt to guard stack red zone failed.");
2878 }
2879 }
2880
2881 void JavaThread::disable_stack_red_zone() {
2882 // The base notation is from the stacks point of view, growing downward.
2883 // We need to adjust it to work correctly with guard_memory()
2884 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2885 address base = stack_red_zone_base() - stack_red_zone_size();
2886 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2887 warning("Attempt to unguard stack red zone failed.");
2888 }
2889 }
2890
2891 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2892 // ignore is there is no stack
2893 if (!has_last_Java_frame()) return;
2894 // traverse the stack frames. Starts from top frame.
2895 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2896 frame* fr = fst.current();
2897 f(fr, fst.register_map());
2898 }
2899 }
2900
2901
2902 #ifndef PRODUCT
2903 // Deoptimization
2904 // Function for testing deoptimization
2905 void JavaThread::deoptimize() {
2906 StackFrameStream fst(this, false);
2907 bool deopt = false; // Dump stack only if a deopt actually happens.
2908 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2909 // Iterate over all frames in the thread and deoptimize
2910 for (; !fst.is_done(); fst.next()) {
2911 if (fst.current()->can_be_deoptimized()) {
2912
2913 if (only_at) {
2914 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2915 // consists of comma or carriage return separated numbers so
2916 // search for the current bci in that string.
2917 address pc = fst.current()->pc();
2918 nmethod* nm = (nmethod*) fst.current()->cb();
2919 ScopeDesc* sd = nm->scope_desc_at(pc);
2920 char buffer[8];
2921 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2922 size_t len = strlen(buffer);
2923 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2924 while (found != NULL) {
2925 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2926 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2927 // Check that the bci found is bracketed by terminators.
2928 break;
2929 }
2930 found = strstr(found + 1, buffer);
2931 }
2932 if (!found) {
2933 continue;
2934 }
2935 }
2936
2937 if (DebugDeoptimization && !deopt) {
2938 deopt = true; // One-time only print before deopt
2939 tty->print_cr("[BEFORE Deoptimization]");
2940 trace_frames();
2941 trace_stack();
2942 }
2943 Deoptimization::deoptimize(this, *fst.current());
2944 }
2945 }
2946
2947 if (DebugDeoptimization && deopt) {
2948 tty->print_cr("[AFTER Deoptimization]");
2949 trace_frames();
2950 }
2951 }
2952
2953
2954 // Make zombies
2955 void JavaThread::make_zombies() {
2956 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2957 if (fst.current()->can_be_deoptimized()) {
2958 // it is a Java nmethod
2959 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2960 nm->make_not_entrant();
2961 }
2962 }
2963 }
2964 #endif // PRODUCT
2965
2966
2967 void JavaThread::deoptimize_marked_methods() {
2968 if (!has_last_Java_frame()) return;
2969 StackFrameStream fst(this, false);
2970 for (; !fst.is_done(); fst.next()) {
2971 if (fst.current()->should_be_deoptimized()) {
2972 Deoptimization::deoptimize(this, *fst.current());
2973 }
2974 }
2975 }
2976
2977 // If the caller is a NamedThread, then remember, in the current scope,
2978 // the given JavaThread in its _processed_thread field.
2979 class RememberProcessedThread: public StackObj {
2980 NamedThread* _cur_thr;
2981 public:
2982 RememberProcessedThread(JavaThread* jthr) {
2983 Thread* thread = Thread::current();
2984 if (thread->is_Named_thread()) {
2985 _cur_thr = (NamedThread *)thread;
2986 _cur_thr->set_processed_thread(jthr);
2987 } else {
2988 _cur_thr = NULL;
2989 }
2990 }
2991
2992 ~RememberProcessedThread() {
2993 if (_cur_thr) {
2994 _cur_thr->set_processed_thread(NULL);
2995 }
2996 }
2997 };
2998
2999 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3000 // Verify that the deferred card marks have been flushed.
3001 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
3002
3003 // Traverse the GCHandles
3004 Thread::oops_do(f, cf);
3005
3006 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3007 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
3008
3009 if (has_last_Java_frame()) {
3010 // Record JavaThread to GC thread
3011 RememberProcessedThread rpt(this);
3012
3013 // traverse the registered growable array
3014 if (_array_for_gc != NULL) {
3015 for (int index = 0; index < _array_for_gc->length(); index++) {
3016 f->do_oop(_array_for_gc->adr_at(index));
3017 }
3018 }
3019
3020 // Traverse the monitor chunks
3021 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
3022 chunk->oops_do(f);
3023 }
3024
3025 // Traverse the execution stack
3026 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3027 fst.current()->oops_do(f, cf, fst.register_map());
3028 }
3029 }
3030
3031 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
3032 // If we have deferred set_locals there might be oops waiting to be
3033 // written
3034 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
3035 if (list != NULL) {
3036 for (int i = 0; i < list->length(); i++) {
3037 list->at(i)->oops_do(f);
3038 }
3039 }
3040
3041 // Traverse instance variables at the end since the GC may be moving things
3042 // around using this function
3043 f->do_oop((oop*) &_vm_result);
3044 f->do_oop((oop*) &_exception_oop);
3045 f->do_oop((oop*) &_pending_async_exception);
3046
3047 if (jvmti_thread_state() != NULL) {
3048 jvmti_thread_state()->oops_do(f, cf);
3049 }
3050 }
3051
3052 #ifdef ASSERT
3053 void JavaThread::verify_states_for_handshake() {
3054 // This checks that the thread has a correct frame state during a handshake.
3055 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3056 (has_last_Java_frame() && java_call_counter() > 0),
3057 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3058 has_last_Java_frame(), java_call_counter());
3059 }
3060 #endif
3061
3062 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3063 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3064 (has_last_Java_frame() && java_call_counter() > 0),
3065 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3066 has_last_Java_frame(), java_call_counter());
3067
3068 if (has_last_Java_frame()) {
3069 // Traverse the execution stack
3070 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3071 fst.current()->nmethods_do(cf);
3072 }
3073 }
3074
3075 if (jvmti_thread_state() != NULL) {
3076 jvmti_thread_state()->nmethods_do(cf);
3077 }
3078 }
3079
3080 void JavaThread::metadata_do(MetadataClosure* f) {
3081 if (has_last_Java_frame()) {
3082 // Traverse the execution stack to call f() on the methods in the stack
3083 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3084 fst.current()->metadata_do(f);
3085 }
3086 } else if (is_Compiler_thread()) {
3087 // need to walk ciMetadata in current compile tasks to keep alive.
3088 CompilerThread* ct = (CompilerThread*)this;
3089 if (ct->env() != NULL) {
3090 ct->env()->metadata_do(f);
3091 }
3092 CompileTask* task = ct->task();
3093 if (task != NULL) {
3094 task->metadata_do(f);
3095 }
3096 }
3097 }
3098
3099 // Printing
3100 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3101 switch (_thread_state) {
3102 case _thread_uninitialized: return "_thread_uninitialized";
3103 case _thread_new: return "_thread_new";
3104 case _thread_new_trans: return "_thread_new_trans";
3105 case _thread_in_native: return "_thread_in_native";
3106 case _thread_in_native_trans: return "_thread_in_native_trans";
3107 case _thread_in_vm: return "_thread_in_vm";
3108 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3109 case _thread_in_Java: return "_thread_in_Java";
3110 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3111 case _thread_blocked: return "_thread_blocked";
3112 case _thread_blocked_trans: return "_thread_blocked_trans";
3113 default: return "unknown thread state";
3114 }
3115 }
3116
3117 #ifndef PRODUCT
3118 void JavaThread::print_thread_state_on(outputStream *st) const {
3119 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3120 };
3121 #endif // PRODUCT
3122
3123 // Called by Threads::print() for VM_PrintThreads operation
3124 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3125 st->print_raw("\"");
3126 st->print_raw(get_thread_name());
3127 st->print_raw("\" ");
3128 oop thread_oop = threadObj();
3129 if (thread_oop != NULL) {
3130 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3131 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3132 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3133 }
3134 Thread::print_on(st, print_extended_info);
3135 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3136 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3137 if (thread_oop != NULL) {
3138 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3139 }
3140 #ifndef PRODUCT
3141 _safepoint_state->print_on(st);
3142 #endif // PRODUCT
3143 if (is_Compiler_thread()) {
3144 CompileTask *task = ((CompilerThread*)this)->task();
3145 if (task != NULL) {
3146 st->print(" Compiling: ");
3147 task->print(st, NULL, true, false);
3148 } else {
3149 st->print(" No compile task");
3150 }
3151 st->cr();
3152 }
3153 }
3154
3155 void JavaThread::print() const { print_on(tty); }
3156
3157 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3158 st->print("%s", get_thread_name_string(buf, buflen));
3159 }
3160
3161 // Called by fatal error handler. The difference between this and
3162 // JavaThread::print() is that we can't grab lock or allocate memory.
3163 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3164 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3165 oop thread_obj = threadObj();
3166 if (thread_obj != NULL) {
3167 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3168 }
3169 st->print(" [");
3170 st->print("%s", _get_thread_state_name(_thread_state));
3171 if (osthread()) {
3172 st->print(", id=%d", osthread()->thread_id());
3173 }
3174 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3175 p2i(stack_end()), p2i(stack_base()));
3176 st->print("]");
3177
3178 ThreadsSMRSupport::print_info_on(this, st);
3179 return;
3180 }
3181
3182 // Verification
3183
3184 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3185
3186 void JavaThread::verify() {
3187 // Verify oops in the thread.
3188 oops_do(&VerifyOopClosure::verify_oop, NULL);
3189
3190 // Verify the stack frames.
3191 frames_do(frame_verify);
3192 }
3193
3194 // CR 6300358 (sub-CR 2137150)
3195 // Most callers of this method assume that it can't return NULL but a
3196 // thread may not have a name whilst it is in the process of attaching to
3197 // the VM - see CR 6412693, and there are places where a JavaThread can be
3198 // seen prior to having it's threadObj set (eg JNI attaching threads and
3199 // if vm exit occurs during initialization). These cases can all be accounted
3200 // for such that this method never returns NULL.
3201 const char* JavaThread::get_thread_name() const {
3202 #ifdef ASSERT
3203 // early safepoints can hit while current thread does not yet have TLS
3204 if (!SafepointSynchronize::is_at_safepoint()) {
3205 Thread *cur = Thread::current();
3206 if (!(cur->is_Java_thread() && cur == this)) {
3207 // Current JavaThreads are allowed to get their own name without
3208 // the Threads_lock.
3209 assert_locked_or_safepoint_or_handshake(Threads_lock, this);
3210 }
3211 }
3212 #endif // ASSERT
3213 return get_thread_name_string();
3214 }
3215
3216 // Returns a non-NULL representation of this thread's name, or a suitable
3217 // descriptive string if there is no set name
3218 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3219 const char* name_str;
3220 oop thread_obj = threadObj();
3221 if (thread_obj != NULL) {
3222 oop name = java_lang_Thread::name(thread_obj);
3223 if (name != NULL) {
3224 if (buf == NULL) {
3225 name_str = java_lang_String::as_utf8_string(name);
3226 } else {
3227 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3228 }
3229 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3230 name_str = "<no-name - thread is attaching>";
3231 } else {
3232 name_str = Thread::name();
3233 }
3234 } else {
3235 name_str = Thread::name();
3236 }
3237 assert(name_str != NULL, "unexpected NULL thread name");
3238 return name_str;
3239 }
3240
3241 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3242
3243 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3244 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3245 // Link Java Thread object <-> C++ Thread
3246
3247 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3248 // and put it into a new Handle. The Handle "thread_oop" can then
3249 // be used to pass the C++ thread object to other methods.
3250
3251 // Set the Java level thread object (jthread) field of the
3252 // new thread (a JavaThread *) to C++ thread object using the
3253 // "thread_oop" handle.
3254
3255 // Set the thread field (a JavaThread *) of the
3256 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3257
3258 Handle thread_oop(Thread::current(),
3259 JNIHandles::resolve_non_null(jni_thread));
3260 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3261 "must be initialized");
3262 set_threadObj(thread_oop());
3263 java_lang_Thread::set_thread(thread_oop(), this);
3264
3265 if (prio == NoPriority) {
3266 prio = java_lang_Thread::priority(thread_oop());
3267 assert(prio != NoPriority, "A valid priority should be present");
3268 }
3269
3270 // Push the Java priority down to the native thread; needs Threads_lock
3271 Thread::set_priority(this, prio);
3272
3273 // Add the new thread to the Threads list and set it in motion.
3274 // We must have threads lock in order to call Threads::add.
3275 // It is crucial that we do not block before the thread is
3276 // added to the Threads list for if a GC happens, then the java_thread oop
3277 // will not be visited by GC.
3278 Threads::add(this);
3279 }
3280
3281 oop JavaThread::current_park_blocker() {
3282 // Support for JSR-166 locks
3283 oop thread_oop = threadObj();
3284 if (thread_oop != NULL) {
3285 return java_lang_Thread::park_blocker(thread_oop);
3286 }
3287 return NULL;
3288 }
3289
3290
3291 void JavaThread::print_stack_on(outputStream* st) {
3292 if (!has_last_Java_frame()) return;
3293
3294 Thread* current_thread = Thread::current();
3295 ResourceMark rm(current_thread);
3296 HandleMark hm(current_thread);
3297
3298 RegisterMap reg_map(this);
3299 vframe* start_vf = last_java_vframe(®_map);
3300 int count = 0;
3301 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3302 if (f->is_java_frame()) {
3303 javaVFrame* jvf = javaVFrame::cast(f);
3304 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3305
3306 // Print out lock information
3307 if (JavaMonitorsInStackTrace) {
3308 jvf->print_lock_info_on(st, count);
3309 }
3310 } else {
3311 // Ignore non-Java frames
3312 }
3313
3314 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3315 count++;
3316 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3317 }
3318 }
3319
3320
3321 // JVMTI PopFrame support
3322 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3323 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3324 if (in_bytes(size_in_bytes) != 0) {
3325 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3326 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3327 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3328 }
3329 }
3330
3331 void* JavaThread::popframe_preserved_args() {
3332 return _popframe_preserved_args;
3333 }
3334
3335 ByteSize JavaThread::popframe_preserved_args_size() {
3336 return in_ByteSize(_popframe_preserved_args_size);
3337 }
3338
3339 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3340 int sz = in_bytes(popframe_preserved_args_size());
3341 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3342 return in_WordSize(sz / wordSize);
3343 }
3344
3345 void JavaThread::popframe_free_preserved_args() {
3346 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3347 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3348 _popframe_preserved_args = NULL;
3349 _popframe_preserved_args_size = 0;
3350 }
3351
3352 #ifndef PRODUCT
3353
3354 void JavaThread::trace_frames() {
3355 tty->print_cr("[Describe stack]");
3356 int frame_no = 1;
3357 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3358 tty->print(" %d. ", frame_no++);
3359 fst.current()->print_value_on(tty, this);
3360 tty->cr();
3361 }
3362 }
3363
3364 class PrintAndVerifyOopClosure: public OopClosure {
3365 protected:
3366 template <class T> inline void do_oop_work(T* p) {
3367 oop obj = RawAccess<>::oop_load(p);
3368 if (obj == NULL) return;
3369 tty->print(INTPTR_FORMAT ": ", p2i(p));
3370 if (oopDesc::is_oop_or_null(obj)) {
3371 if (obj->is_objArray()) {
3372 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3373 } else {
3374 obj->print();
3375 }
3376 } else {
3377 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3378 }
3379 tty->cr();
3380 }
3381 public:
3382 virtual void do_oop(oop* p) { do_oop_work(p); }
3383 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3384 };
3385
3386 #ifdef ASSERT
3387 // Print or validate the layout of stack frames
3388 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3389 ResourceMark rm;
3390 PRESERVE_EXCEPTION_MARK;
3391 FrameValues values;
3392 int frame_no = 0;
3393 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3394 fst.current()->describe(values, ++frame_no);
3395 if (depth == frame_no) break;
3396 }
3397 if (validate_only) {
3398 values.validate();
3399 } else {
3400 tty->print_cr("[Describe stack layout]");
3401 values.print(this);
3402 }
3403 }
3404 #endif
3405
3406 void JavaThread::trace_stack_from(vframe* start_vf) {
3407 ResourceMark rm;
3408 int vframe_no = 1;
3409 for (vframe* f = start_vf; f; f = f->sender()) {
3410 if (f->is_java_frame()) {
3411 javaVFrame::cast(f)->print_activation(vframe_no++);
3412 } else {
3413 f->print();
3414 }
3415 if (vframe_no > StackPrintLimit) {
3416 tty->print_cr("...<more frames>...");
3417 return;
3418 }
3419 }
3420 }
3421
3422
3423 void JavaThread::trace_stack() {
3424 if (!has_last_Java_frame()) return;
3425 Thread* current_thread = Thread::current();
3426 ResourceMark rm(current_thread);
3427 HandleMark hm(current_thread);
3428 RegisterMap reg_map(this);
3429 trace_stack_from(last_java_vframe(®_map));
3430 }
3431
3432
3433 #endif // PRODUCT
3434
3435
3436 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3437 assert(reg_map != NULL, "a map must be given");
3438 frame f = last_frame();
3439 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3440 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3441 }
3442 return NULL;
3443 }
3444
3445
3446 Klass* JavaThread::security_get_caller_class(int depth) {
3447 vframeStream vfst(this);
3448 vfst.security_get_caller_frame(depth);
3449 if (!vfst.at_end()) {
3450 return vfst.method()->method_holder();
3451 }
3452 return NULL;
3453 }
3454
3455 // java.lang.Thread.sleep support
3456 // Returns true if sleep time elapsed as expected, and false
3457 // if the thread was interrupted.
3458 bool JavaThread::sleep(jlong millis) {
3459 assert(this == Thread::current(), "thread consistency check");
3460
3461 ParkEvent * const slp = this->_SleepEvent;
3462 // Because there can be races with thread interruption sending an unpark()
3463 // to the event, we explicitly reset it here to avoid an immediate return.
3464 // The actual interrupt state will be checked before we park().
3465 slp->reset();
3466 // Thread interruption establishes a happens-before ordering in the
3467 // Java Memory Model, so we need to ensure we synchronize with the
3468 // interrupt state.
3469 OrderAccess::fence();
3470
3471 jlong prevtime = os::javaTimeNanos();
3472
3473 for (;;) {
3474 // interruption has precedence over timing out
3475 if (this->is_interrupted(true)) {
3476 return false;
3477 }
3478
3479 if (millis <= 0) {
3480 return true;
3481 }
3482
3483 {
3484 ThreadBlockInVM tbivm(this);
3485 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3486
3487 this->set_suspend_equivalent();
3488 // cleared by handle_special_suspend_equivalent_condition() or
3489 // java_suspend_self() via check_and_wait_while_suspended()
3490
3491 slp->park(millis);
3492
3493 // were we externally suspended while we were waiting?
3494 this->check_and_wait_while_suspended();
3495 }
3496
3497 // Update elapsed time tracking
3498 jlong newtime = os::javaTimeNanos();
3499 if (newtime - prevtime < 0) {
3500 // time moving backwards, should only happen if no monotonic clock
3501 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3502 assert(!os::supports_monotonic_clock(),
3503 "unexpected time moving backwards detected in JavaThread::sleep()");
3504 } else {
3505 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3506 }
3507 prevtime = newtime;
3508 }
3509 }
3510
3511 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3512 assert(thread->is_Compiler_thread(), "must be compiler thread");
3513 CompileBroker::compiler_thread_loop();
3514 }
3515
3516 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3517 NMethodSweeper::sweeper_loop();
3518 }
3519
3520 // Create a CompilerThread
3521 CompilerThread::CompilerThread(CompileQueue* queue,
3522 CompilerCounters* counters)
3523 : JavaThread(&compiler_thread_entry) {
3524 _env = NULL;
3525 _log = NULL;
3526 _task = NULL;
3527 _queue = queue;
3528 _counters = counters;
3529 _buffer_blob = NULL;
3530 _compiler = NULL;
3531
3532 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3533 resource_area()->bias_to(mtCompiler);
3534
3535 #ifndef PRODUCT
3536 _ideal_graph_printer = NULL;
3537 #endif
3538 }
3539
3540 CompilerThread::~CompilerThread() {
3541 // Delete objects which were allocated on heap.
3542 delete _counters;
3543 }
3544
3545 bool CompilerThread::can_call_java() const {
3546 return _compiler != NULL && _compiler->is_jvmci();
3547 }
3548
3549 // Create sweeper thread
3550 CodeCacheSweeperThread::CodeCacheSweeperThread()
3551 : JavaThread(&sweeper_thread_entry) {
3552 _scanned_compiled_method = NULL;
3553 }
3554
3555 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3556 JavaThread::oops_do(f, cf);
3557 if (_scanned_compiled_method != NULL && cf != NULL) {
3558 // Safepoints can occur when the sweeper is scanning an nmethod so
3559 // process it here to make sure it isn't unloaded in the middle of
3560 // a scan.
3561 cf->do_code_blob(_scanned_compiled_method);
3562 }
3563 }
3564
3565 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3566 JavaThread::nmethods_do(cf);
3567 if (_scanned_compiled_method != NULL && cf != NULL) {
3568 // Safepoints can occur when the sweeper is scanning an nmethod so
3569 // process it here to make sure it isn't unloaded in the middle of
3570 // a scan.
3571 cf->do_code_blob(_scanned_compiled_method);
3572 }
3573 }
3574
3575
3576 // ======= Threads ========
3577
3578 // The Threads class links together all active threads, and provides
3579 // operations over all threads. It is protected by the Threads_lock,
3580 // which is also used in other global contexts like safepointing.
3581 // ThreadsListHandles are used to safely perform operations on one
3582 // or more threads without the risk of the thread exiting during the
3583 // operation.
3584 //
3585 // Note: The Threads_lock is currently more widely used than we
3586 // would like. We are actively migrating Threads_lock uses to other
3587 // mechanisms in order to reduce Threads_lock contention.
3588
3589 int Threads::_number_of_threads = 0;
3590 int Threads::_number_of_non_daemon_threads = 0;
3591 int Threads::_return_code = 0;
3592 uintx Threads::_thread_claim_token = 1; // Never zero.
3593 size_t JavaThread::_stack_size_at_create = 0;
3594
3595 #ifdef ASSERT
3596 bool Threads::_vm_complete = false;
3597 #endif
3598
3599 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3600 Prefetch::read((void*)addr, prefetch_interval);
3601 return *addr;
3602 }
3603
3604 // Possibly the ugliest for loop the world has seen. C++ does not allow
3605 // multiple types in the declaration section of the for loop. In this case
3606 // we are only dealing with pointers and hence can cast them. It looks ugly
3607 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3608 #define DO_JAVA_THREADS(LIST, X) \
3609 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3610 *MACRO_list = (JavaThread*)(LIST), \
3611 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3612 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3613 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3614 MACRO_current_p != MACRO_end; \
3615 MACRO_current_p++, \
3616 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3617
3618 // All JavaThreads
3619 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3620
3621 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3622 void Threads::non_java_threads_do(ThreadClosure* tc) {
3623 NoSafepointVerifier nsv;
3624 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3625 tc->do_thread(njti.current());
3626 }
3627 }
3628
3629 // All JavaThreads
3630 void Threads::java_threads_do(ThreadClosure* tc) {
3631 assert_locked_or_safepoint(Threads_lock);
3632 // ALL_JAVA_THREADS iterates through all JavaThreads.
3633 ALL_JAVA_THREADS(p) {
3634 tc->do_thread(p);
3635 }
3636 }
3637
3638 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3639 assert_locked_or_safepoint(Threads_lock);
3640 java_threads_do(tc);
3641 tc->do_thread(VMThread::vm_thread());
3642 }
3643
3644 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3645 void Threads::threads_do(ThreadClosure* tc) {
3646 assert_locked_or_safepoint(Threads_lock);
3647 java_threads_do(tc);
3648 non_java_threads_do(tc);
3649 }
3650
3651 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3652 uintx claim_token = Threads::thread_claim_token();
3653 ALL_JAVA_THREADS(p) {
3654 if (p->claim_threads_do(is_par, claim_token)) {
3655 tc->do_thread(p);
3656 }
3657 }
3658 VMThread* vmt = VMThread::vm_thread();
3659 if (vmt->claim_threads_do(is_par, claim_token)) {
3660 tc->do_thread(vmt);
3661 }
3662 }
3663
3664 // The system initialization in the library has three phases.
3665 //
3666 // Phase 1: java.lang.System class initialization
3667 // java.lang.System is a primordial class loaded and initialized
3668 // by the VM early during startup. java.lang.System.<clinit>
3669 // only does registerNatives and keeps the rest of the class
3670 // initialization work later until thread initialization completes.
3671 //
3672 // System.initPhase1 initializes the system properties, the static
3673 // fields in, out, and err. Set up java signal handlers, OS-specific
3674 // system settings, and thread group of the main thread.
3675 static void call_initPhase1(TRAPS) {
3676 Klass* klass = SystemDictionary::System_klass();
3677 JavaValue result(T_VOID);
3678 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3679 vmSymbols::void_method_signature(), CHECK);
3680 }
3681
3682 // Phase 2. Module system initialization
3683 // This will initialize the module system. Only java.base classes
3684 // can be loaded until phase 2 completes.
3685 //
3686 // Call System.initPhase2 after the compiler initialization and jsr292
3687 // classes get initialized because module initialization runs a lot of java
3688 // code, that for performance reasons, should be compiled. Also, this will
3689 // enable the startup code to use lambda and other language features in this
3690 // phase and onward.
3691 //
3692 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3693 static void call_initPhase2(TRAPS) {
3694 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3695
3696 Klass* klass = SystemDictionary::System_klass();
3697
3698 JavaValue result(T_INT);
3699 JavaCallArguments args;
3700 args.push_int(DisplayVMOutputToStderr);
3701 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3702 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3703 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3704 if (result.get_jint() != JNI_OK) {
3705 vm_exit_during_initialization(); // no message or exception
3706 }
3707
3708 universe_post_module_init();
3709 }
3710
3711 // Phase 3. final setup - set security manager, system class loader and TCCL
3712 //
3713 // This will instantiate and set the security manager, set the system class
3714 // loader as well as the thread context class loader. The security manager
3715 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3716 // other modules or the application's classpath.
3717 static void call_initPhase3(TRAPS) {
3718 Klass* klass = SystemDictionary::System_klass();
3719 JavaValue result(T_VOID);
3720 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3721 vmSymbols::void_method_signature(), CHECK);
3722 }
3723
3724 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3725 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3726
3727 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3728 create_vm_init_libraries();
3729 }
3730
3731 initialize_class(vmSymbols::java_lang_String(), CHECK);
3732
3733 // Inject CompactStrings value after the static initializers for String ran.
3734 java_lang_String::set_compact_strings(CompactStrings);
3735
3736 // Initialize java_lang.System (needed before creating the thread)
3737 initialize_class(vmSymbols::java_lang_System(), CHECK);
3738 // The VM creates & returns objects of this class. Make sure it's initialized.
3739 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3740 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3741 Handle thread_group = create_initial_thread_group(CHECK);
3742 Universe::set_main_thread_group(thread_group());
3743 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3744 create_initial_thread(thread_group, main_thread, CHECK);
3745
3746 // The VM creates objects of this class.
3747 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3748
3749 #ifdef ASSERT
3750 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3751 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3752 #endif
3753
3754 // initialize the hardware-specific constants needed by Unsafe
3755 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3756 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3757
3758 // The VM preresolves methods to these classes. Make sure that they get initialized
3759 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3760 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3761
3762 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3763 call_initPhase1(CHECK);
3764
3765 // get the Java runtime name, version, and vendor info after java.lang.System is initialized
3766 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3767 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3768 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD));
3769 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD));
3770
3771 // an instance of OutOfMemory exception has been allocated earlier
3772 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3773 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3774 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3775 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3776 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3777 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3778 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3779 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3780
3781 // Eager box cache initialization only if AOT is on and any library is loaded.
3782 AOTLoader::initialize_box_caches(CHECK);
3783 }
3784
3785 void Threads::initialize_jsr292_core_classes(TRAPS) {
3786 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3787
3788 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3789 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3790 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3791 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3792 }
3793
3794 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3795 extern void JDK_Version_init();
3796
3797 // Preinitialize version info.
3798 VM_Version::early_initialize();
3799
3800 // Check version
3801 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3802
3803 // Initialize library-based TLS
3804 ThreadLocalStorage::init();
3805
3806 // Initialize the output stream module
3807 ostream_init();
3808
3809 // Process java launcher properties.
3810 Arguments::process_sun_java_launcher_properties(args);
3811
3812 // Initialize the os module
3813 os::init();
3814
3815 // Record VM creation timing statistics
3816 TraceVmCreationTime create_vm_timer;
3817 create_vm_timer.start();
3818
3819 // Initialize system properties.
3820 Arguments::init_system_properties();
3821
3822 // So that JDK version can be used as a discriminator when parsing arguments
3823 JDK_Version_init();
3824
3825 // Update/Initialize System properties after JDK version number is known
3826 Arguments::init_version_specific_system_properties();
3827
3828 // Make sure to initialize log configuration *before* parsing arguments
3829 LogConfiguration::initialize(create_vm_timer.begin_time());
3830
3831 // Parse arguments
3832 // Note: this internally calls os::init_container_support()
3833 jint parse_result = Arguments::parse(args);
3834 if (parse_result != JNI_OK) return parse_result;
3835
3836 os::init_before_ergo();
3837
3838 jint ergo_result = Arguments::apply_ergo();
3839 if (ergo_result != JNI_OK) return ergo_result;
3840
3841 // Final check of all ranges after ergonomics which may change values.
3842 if (!JVMFlagRangeList::check_ranges()) {
3843 return JNI_EINVAL;
3844 }
3845
3846 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3847 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3848 if (!constraint_result) {
3849 return JNI_EINVAL;
3850 }
3851
3852 if (PauseAtStartup) {
3853 os::pause();
3854 }
3855
3856 HOTSPOT_VM_INIT_BEGIN();
3857
3858 // Timing (must come after argument parsing)
3859 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3860
3861 // Initialize the os module after parsing the args
3862 jint os_init_2_result = os::init_2();
3863 if (os_init_2_result != JNI_OK) return os_init_2_result;
3864
3865 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3866 // Initialize assert poison page mechanism.
3867 if (ShowRegistersOnAssert) {
3868 initialize_assert_poison();
3869 }
3870 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3871
3872 SafepointMechanism::initialize();
3873
3874 jint adjust_after_os_result = Arguments::adjust_after_os();
3875 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3876
3877 // Initialize output stream logging
3878 ostream_init_log();
3879
3880 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3881 // Must be before create_vm_init_agents()
3882 if (Arguments::init_libraries_at_startup()) {
3883 convert_vm_init_libraries_to_agents();
3884 }
3885
3886 // Launch -agentlib/-agentpath and converted -Xrun agents
3887 if (Arguments::init_agents_at_startup()) {
3888 create_vm_init_agents();
3889 }
3890
3891 // Initialize Threads state
3892 _number_of_threads = 0;
3893 _number_of_non_daemon_threads = 0;
3894
3895 // Initialize global data structures and create system classes in heap
3896 vm_init_globals();
3897
3898 #if INCLUDE_JVMCI
3899 if (JVMCICounterSize > 0) {
3900 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3901 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3902 } else {
3903 JavaThread::_jvmci_old_thread_counters = NULL;
3904 }
3905 #endif // INCLUDE_JVMCI
3906
3907 // Initialize OopStorage for threadObj
3908 _thread_oop_storage = OopStorageSet::create_strong("Thread OopStorage");
3909
3910 // Attach the main thread to this os thread
3911 JavaThread* main_thread = new JavaThread();
3912 main_thread->set_thread_state(_thread_in_vm);
3913 main_thread->initialize_thread_current();
3914 // must do this before set_active_handles
3915 main_thread->record_stack_base_and_size();
3916 main_thread->register_thread_stack_with_NMT();
3917 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3918
3919 if (!main_thread->set_as_starting_thread()) {
3920 vm_shutdown_during_initialization(
3921 "Failed necessary internal allocation. Out of swap space");
3922 main_thread->smr_delete();
3923 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3924 return JNI_ENOMEM;
3925 }
3926
3927 // Enable guard page *after* os::create_main_thread(), otherwise it would
3928 // crash Linux VM, see notes in os_linux.cpp.
3929 main_thread->create_stack_guard_pages();
3930
3931 // Initialize Java-Level synchronization subsystem
3932 ObjectMonitor::Initialize();
3933
3934 // Initialize global modules
3935 jint status = init_globals();
3936 if (status != JNI_OK) {
3937 main_thread->smr_delete();
3938 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3939 return status;
3940 }
3941
3942 JFR_ONLY(Jfr::on_create_vm_1();)
3943
3944 // Should be done after the heap is fully created
3945 main_thread->cache_global_variables();
3946
3947 { MutexLocker mu(Threads_lock);
3948 Threads::add(main_thread);
3949 }
3950
3951 // Any JVMTI raw monitors entered in onload will transition into
3952 // real raw monitor. VM is setup enough here for raw monitor enter.
3953 JvmtiExport::transition_pending_onload_raw_monitors();
3954
3955 // Create the VMThread
3956 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3957
3958 VMThread::create();
3959 Thread* vmthread = VMThread::vm_thread();
3960
3961 if (!os::create_thread(vmthread, os::vm_thread)) {
3962 vm_exit_during_initialization("Cannot create VM thread. "
3963 "Out of system resources.");
3964 }
3965
3966 // Wait for the VM thread to become ready, and VMThread::run to initialize
3967 // Monitors can have spurious returns, must always check another state flag
3968 {
3969 MonitorLocker ml(Notify_lock);
3970 os::start_thread(vmthread);
3971 while (vmthread->active_handles() == NULL) {
3972 ml.wait();
3973 }
3974 }
3975 }
3976
3977 assert(Universe::is_fully_initialized(), "not initialized");
3978 if (VerifyDuringStartup) {
3979 // Make sure we're starting with a clean slate.
3980 VM_Verify verify_op;
3981 VMThread::execute(&verify_op);
3982 }
3983
3984 // We need this to update the java.vm.info property in case any flags used
3985 // to initially define it have been changed. This is needed for both CDS and
3986 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3987 // is initially computed. See Abstract_VM_Version::vm_info_string().
3988 // This update must happen before we initialize the java classes, but
3989 // after any initialization logic that might modify the flags.
3990 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3991
3992 Thread* THREAD = Thread::current();
3993 HandleMark hm(THREAD);
3994
3995 // Always call even when there are not JVMTI environments yet, since environments
3996 // may be attached late and JVMTI must track phases of VM execution
3997 JvmtiExport::enter_early_start_phase();
3998
3999 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4000 JvmtiExport::post_early_vm_start();
4001
4002 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
4003
4004 quicken_jni_functions();
4005
4006 // No more stub generation allowed after that point.
4007 StubCodeDesc::freeze();
4008
4009 // Set flag that basic initialization has completed. Used by exceptions and various
4010 // debug stuff, that does not work until all basic classes have been initialized.
4011 set_init_completed();
4012
4013 LogConfiguration::post_initialize();
4014 Metaspace::post_initialize();
4015
4016 HOTSPOT_VM_INIT_END();
4017
4018 // record VM initialization completion time
4019 #if INCLUDE_MANAGEMENT
4020 Management::record_vm_init_completed();
4021 #endif // INCLUDE_MANAGEMENT
4022
4023 // Signal Dispatcher needs to be started before VMInit event is posted
4024 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
4025
4026 // Start Attach Listener if +StartAttachListener or it can't be started lazily
4027 if (!DisableAttachMechanism) {
4028 AttachListener::vm_start();
4029 if (StartAttachListener || AttachListener::init_at_startup()) {
4030 AttachListener::init();
4031 }
4032 }
4033
4034 // Launch -Xrun agents
4035 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4036 // back-end can launch with -Xdebug -Xrunjdwp.
4037 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4038 create_vm_init_libraries();
4039 }
4040
4041 if (CleanChunkPoolAsync) {
4042 Chunk::start_chunk_pool_cleaner_task();
4043 }
4044
4045 // Start the service thread
4046 // The service thread enqueues JVMTI deferred events and does various hashtable
4047 // and other cleanups. Needs to start before the compilers start posting events.
4048 ServiceThread::initialize();
4049
4050 // initialize compiler(s)
4051 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4052 #if INCLUDE_JVMCI
4053 bool force_JVMCI_intialization = false;
4054 if (EnableJVMCI) {
4055 // Initialize JVMCI eagerly when it is explicitly requested.
4056 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
4057 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4058
4059 if (!force_JVMCI_intialization) {
4060 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4061 // compilations via JVMCI will not actually block until JVMCI is initialized.
4062 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4063 }
4064 }
4065 #endif
4066 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4067 // Postpone completion of compiler initialization to after JVMCI
4068 // is initialized to avoid timeouts of blocking compilations.
4069 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4070 CompileBroker::compilation_init_phase2();
4071 }
4072 #endif
4073
4074 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4075 // It is done after compilers are initialized, because otherwise compilations of
4076 // signature polymorphic MH intrinsics can be missed
4077 // (see SystemDictionary::find_method_handle_intrinsic).
4078 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4079
4080 // This will initialize the module system. Only java.base classes can be
4081 // loaded until phase 2 completes
4082 call_initPhase2(CHECK_JNI_ERR);
4083
4084 JFR_ONLY(Jfr::on_create_vm_2();)
4085
4086 // Always call even when there are not JVMTI environments yet, since environments
4087 // may be attached late and JVMTI must track phases of VM execution
4088 JvmtiExport::enter_start_phase();
4089
4090 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4091 JvmtiExport::post_vm_start();
4092
4093 // Final system initialization including security manager and system class loader
4094 call_initPhase3(CHECK_JNI_ERR);
4095
4096 // cache the system and platform class loaders
4097 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4098
4099 #if INCLUDE_CDS
4100 // capture the module path info from the ModuleEntryTable
4101 ClassLoader::initialize_module_path(THREAD);
4102 #endif
4103
4104 #if INCLUDE_JVMCI
4105 if (force_JVMCI_intialization) {
4106 JVMCI::initialize_compiler(CHECK_JNI_ERR);
4107 CompileBroker::compilation_init_phase2();
4108 }
4109 #endif
4110
4111 // Always call even when there are not JVMTI environments yet, since environments
4112 // may be attached late and JVMTI must track phases of VM execution
4113 JvmtiExport::enter_live_phase();
4114
4115 // Make perfmemory accessible
4116 PerfMemory::set_accessible(true);
4117
4118 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4119 JvmtiExport::post_vm_initialized();
4120
4121 JFR_ONLY(Jfr::on_create_vm_3();)
4122
4123 #if INCLUDE_MANAGEMENT
4124 Management::initialize(THREAD);
4125
4126 if (HAS_PENDING_EXCEPTION) {
4127 // management agent fails to start possibly due to
4128 // configuration problem and is responsible for printing
4129 // stack trace if appropriate. Simply exit VM.
4130 vm_exit(1);
4131 }
4132 #endif // INCLUDE_MANAGEMENT
4133
4134 if (MemProfiling) MemProfiler::engage();
4135 StatSampler::engage();
4136 if (CheckJNICalls) JniPeriodicChecker::engage();
4137
4138 BiasedLocking::init();
4139
4140 #if INCLUDE_RTM_OPT
4141 RTMLockingCounters::init();
4142 #endif
4143
4144 call_postVMInitHook(THREAD);
4145 // The Java side of PostVMInitHook.run must deal with all
4146 // exceptions and provide means of diagnosis.
4147 if (HAS_PENDING_EXCEPTION) {
4148 CLEAR_PENDING_EXCEPTION;
4149 }
4150
4151 {
4152 MutexLocker ml(PeriodicTask_lock);
4153 // Make sure the WatcherThread can be started by WatcherThread::start()
4154 // or by dynamic enrollment.
4155 WatcherThread::make_startable();
4156 // Start up the WatcherThread if there are any periodic tasks
4157 // NOTE: All PeriodicTasks should be registered by now. If they
4158 // aren't, late joiners might appear to start slowly (we might
4159 // take a while to process their first tick).
4160 if (PeriodicTask::num_tasks() > 0) {
4161 WatcherThread::start();
4162 }
4163 }
4164
4165 create_vm_timer.end();
4166 #ifdef ASSERT
4167 _vm_complete = true;
4168 #endif
4169
4170 if (DumpSharedSpaces) {
4171 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4172 ShouldNotReachHere();
4173 }
4174
4175 return JNI_OK;
4176 }
4177
4178 // type for the Agent_OnLoad and JVM_OnLoad entry points
4179 extern "C" {
4180 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4181 }
4182 // Find a command line agent library and return its entry point for
4183 // -agentlib: -agentpath: -Xrun
4184 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4185 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4186 const char *on_load_symbols[],
4187 size_t num_symbol_entries) {
4188 OnLoadEntry_t on_load_entry = NULL;
4189 void *library = NULL;
4190
4191 if (!agent->valid()) {
4192 char buffer[JVM_MAXPATHLEN];
4193 char ebuf[1024] = "";
4194 const char *name = agent->name();
4195 const char *msg = "Could not find agent library ";
4196
4197 // First check to see if agent is statically linked into executable
4198 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4199 library = agent->os_lib();
4200 } else if (agent->is_absolute_path()) {
4201 library = os::dll_load(name, ebuf, sizeof ebuf);
4202 if (library == NULL) {
4203 const char *sub_msg = " in absolute path, with error: ";
4204 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4205 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4206 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4207 // If we can't find the agent, exit.
4208 vm_exit_during_initialization(buf, NULL);
4209 FREE_C_HEAP_ARRAY(char, buf);
4210 }
4211 } else {
4212 // Try to load the agent from the standard dll directory
4213 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4214 name)) {
4215 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4216 }
4217 if (library == NULL) { // Try the library path directory.
4218 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4219 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4220 }
4221 if (library == NULL) {
4222 const char *sub_msg = " on the library path, with error: ";
4223 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4224
4225 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4226 strlen(ebuf) + strlen(sub_msg2) + 1;
4227 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4228 if (!agent->is_instrument_lib()) {
4229 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4230 } else {
4231 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4232 }
4233 // If we can't find the agent, exit.
4234 vm_exit_during_initialization(buf, NULL);
4235 FREE_C_HEAP_ARRAY(char, buf);
4236 }
4237 }
4238 }
4239 agent->set_os_lib(library);
4240 agent->set_valid();
4241 }
4242
4243 // Find the OnLoad function.
4244 on_load_entry =
4245 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4246 false,
4247 on_load_symbols,
4248 num_symbol_entries));
4249 return on_load_entry;
4250 }
4251
4252 // Find the JVM_OnLoad entry point
4253 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4254 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4255 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4256 }
4257
4258 // Find the Agent_OnLoad entry point
4259 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4260 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4261 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4262 }
4263
4264 // For backwards compatibility with -Xrun
4265 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4266 // treated like -agentpath:
4267 // Must be called before agent libraries are created
4268 void Threads::convert_vm_init_libraries_to_agents() {
4269 AgentLibrary* agent;
4270 AgentLibrary* next;
4271
4272 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4273 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4274 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4275
4276 // If there is an JVM_OnLoad function it will get called later,
4277 // otherwise see if there is an Agent_OnLoad
4278 if (on_load_entry == NULL) {
4279 on_load_entry = lookup_agent_on_load(agent);
4280 if (on_load_entry != NULL) {
4281 // switch it to the agent list -- so that Agent_OnLoad will be called,
4282 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4283 Arguments::convert_library_to_agent(agent);
4284 } else {
4285 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4286 }
4287 }
4288 }
4289 }
4290
4291 // Create agents for -agentlib: -agentpath: and converted -Xrun
4292 // Invokes Agent_OnLoad
4293 // Called very early -- before JavaThreads exist
4294 void Threads::create_vm_init_agents() {
4295 extern struct JavaVM_ main_vm;
4296 AgentLibrary* agent;
4297
4298 JvmtiExport::enter_onload_phase();
4299
4300 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4301 // CDS dumping does not support native JVMTI agent.
4302 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4303 if (Arguments::is_dumping_archive()) {
4304 if(!agent->is_instrument_lib()) {
4305 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4306 } else if (!AllowArchivingWithJavaAgent) {
4307 vm_exit_during_cds_dumping(
4308 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4309 }
4310 }
4311
4312 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4313
4314 if (on_load_entry != NULL) {
4315 // Invoke the Agent_OnLoad function
4316 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4317 if (err != JNI_OK) {
4318 vm_exit_during_initialization("agent library failed to init", agent->name());
4319 }
4320 } else {
4321 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4322 }
4323 }
4324
4325 JvmtiExport::enter_primordial_phase();
4326 }
4327
4328 extern "C" {
4329 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4330 }
4331
4332 void Threads::shutdown_vm_agents() {
4333 // Send any Agent_OnUnload notifications
4334 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4335 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4336 extern struct JavaVM_ main_vm;
4337 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4338
4339 // Find the Agent_OnUnload function.
4340 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4341 os::find_agent_function(agent,
4342 false,
4343 on_unload_symbols,
4344 num_symbol_entries));
4345
4346 // Invoke the Agent_OnUnload function
4347 if (unload_entry != NULL) {
4348 JavaThread* thread = JavaThread::current();
4349 ThreadToNativeFromVM ttn(thread);
4350 HandleMark hm(thread);
4351 (*unload_entry)(&main_vm);
4352 }
4353 }
4354 }
4355
4356 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4357 // Invokes JVM_OnLoad
4358 void Threads::create_vm_init_libraries() {
4359 extern struct JavaVM_ main_vm;
4360 AgentLibrary* agent;
4361
4362 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4363 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4364
4365 if (on_load_entry != NULL) {
4366 // Invoke the JVM_OnLoad function
4367 JavaThread* thread = JavaThread::current();
4368 ThreadToNativeFromVM ttn(thread);
4369 HandleMark hm(thread);
4370 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4371 if (err != JNI_OK) {
4372 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4373 }
4374 } else {
4375 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4376 }
4377 }
4378 }
4379
4380
4381 // Last thread running calls java.lang.Shutdown.shutdown()
4382 void JavaThread::invoke_shutdown_hooks() {
4383 HandleMark hm(this);
4384
4385 // Link all classes for dynamic CDS dumping before vm exit.
4386 // Same operation is being done in JVM_BeforeHalt for handling the
4387 // case where the application calls System.exit().
4388 if (DynamicDumpSharedSpaces) {
4389 MetaspaceShared::link_and_cleanup_shared_classes(this);
4390 }
4391
4392 // We could get here with a pending exception, if so clear it now.
4393 if (this->has_pending_exception()) {
4394 this->clear_pending_exception();
4395 }
4396
4397 EXCEPTION_MARK;
4398 Klass* shutdown_klass =
4399 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4400 THREAD);
4401 if (shutdown_klass != NULL) {
4402 // SystemDictionary::resolve_or_null will return null if there was
4403 // an exception. If we cannot load the Shutdown class, just don't
4404 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4405 // won't be run. Note that if a shutdown hook was registered,
4406 // the Shutdown class would have already been loaded
4407 // (Runtime.addShutdownHook will load it).
4408 JavaValue result(T_VOID);
4409 JavaCalls::call_static(&result,
4410 shutdown_klass,
4411 vmSymbols::shutdown_name(),
4412 vmSymbols::void_method_signature(),
4413 THREAD);
4414 }
4415 CLEAR_PENDING_EXCEPTION;
4416 }
4417
4418 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4419 // the program falls off the end of main(). Another VM exit path is through
4420 // vm_exit() when the program calls System.exit() to return a value or when
4421 // there is a serious error in VM. The two shutdown paths are not exactly
4422 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4423 // and VM_Exit op at VM level.
4424 //
4425 // Shutdown sequence:
4426 // + Shutdown native memory tracking if it is on
4427 // + Wait until we are the last non-daemon thread to execute
4428 // <-- every thing is still working at this moment -->
4429 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4430 // shutdown hooks
4431 // + Call before_exit(), prepare for VM exit
4432 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4433 // currently the only user of this mechanism is File.deleteOnExit())
4434 // > stop StatSampler, watcher thread,
4435 // post thread end and vm death events to JVMTI,
4436 // stop signal thread
4437 // + Call JavaThread::exit(), it will:
4438 // > release JNI handle blocks, remove stack guard pages
4439 // > remove this thread from Threads list
4440 // <-- no more Java code from this thread after this point -->
4441 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4442 // the compiler threads at safepoint
4443 // <-- do not use anything that could get blocked by Safepoint -->
4444 // + Disable tracing at JNI/JVM barriers
4445 // + Set _vm_exited flag for threads that are still running native code
4446 // + Call exit_globals()
4447 // > deletes tty
4448 // > deletes PerfMemory resources
4449 // + Delete this thread
4450 // + Return to caller
4451
4452 bool Threads::destroy_vm() {
4453 JavaThread* thread = JavaThread::current();
4454
4455 #ifdef ASSERT
4456 _vm_complete = false;
4457 #endif
4458 // Wait until we are the last non-daemon thread to execute
4459 { MonitorLocker nu(Threads_lock);
4460 while (Threads::number_of_non_daemon_threads() > 1)
4461 // This wait should make safepoint checks, wait without a timeout,
4462 // and wait as a suspend-equivalent condition.
4463 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4464 }
4465
4466 EventShutdown e;
4467 if (e.should_commit()) {
4468 e.set_reason("No remaining non-daemon Java threads");
4469 e.commit();
4470 }
4471
4472 // Hang forever on exit if we are reporting an error.
4473 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4474 os::infinite_sleep();
4475 }
4476 os::wait_for_keypress_at_exit();
4477
4478 // run Java level shutdown hooks
4479 thread->invoke_shutdown_hooks();
4480
4481 before_exit(thread);
4482
4483 thread->exit(true);
4484
4485 // We are no longer on the main thread list but could still be in a
4486 // secondary list where another thread may try to interact with us.
4487 // So wait until all such interactions are complete before we bring
4488 // the VM to the termination safepoint. Normally this would be done
4489 // using thread->smr_delete() below where we delete the thread, but
4490 // we can't call that after the termination safepoint is active as
4491 // we will deadlock on the Threads_lock. Once all interactions are
4492 // complete it is safe to directly delete the thread at any time.
4493 ThreadsSMRSupport::wait_until_not_protected(thread);
4494
4495 // Stop VM thread.
4496 {
4497 // 4945125 The vm thread comes to a safepoint during exit.
4498 // GC vm_operations can get caught at the safepoint, and the
4499 // heap is unparseable if they are caught. Grab the Heap_lock
4500 // to prevent this. The GC vm_operations will not be able to
4501 // queue until after the vm thread is dead. After this point,
4502 // we'll never emerge out of the safepoint before the VM exits.
4503
4504 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4505
4506 VMThread::wait_for_vm_thread_exit();
4507 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4508 VMThread::destroy();
4509 }
4510
4511 // Now, all Java threads are gone except daemon threads. Daemon threads
4512 // running Java code or in VM are stopped by the Safepoint. However,
4513 // daemon threads executing native code are still running. But they
4514 // will be stopped at native=>Java/VM barriers. Note that we can't
4515 // simply kill or suspend them, as it is inherently deadlock-prone.
4516
4517 VM_Exit::set_vm_exited();
4518
4519 // Clean up ideal graph printers after the VMThread has started
4520 // the final safepoint which will block all the Compiler threads.
4521 // Note that this Thread has already logically exited so the
4522 // clean_up() function's use of a JavaThreadIteratorWithHandle
4523 // would be a problem except set_vm_exited() has remembered the
4524 // shutdown thread which is granted a policy exception.
4525 #if defined(COMPILER2) && !defined(PRODUCT)
4526 IdealGraphPrinter::clean_up();
4527 #endif
4528
4529 notify_vm_shutdown();
4530
4531 // exit_globals() will delete tty
4532 exit_globals();
4533
4534 // Deleting the shutdown thread here is safe. See comment on
4535 // wait_until_not_protected() above.
4536 delete thread;
4537
4538 #if INCLUDE_JVMCI
4539 if (JVMCICounterSize > 0) {
4540 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4541 }
4542 #endif
4543
4544 LogConfiguration::finalize();
4545
4546 return true;
4547 }
4548
4549
4550 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4551 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4552 return is_supported_jni_version(version);
4553 }
4554
4555
4556 jboolean Threads::is_supported_jni_version(jint version) {
4557 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4558 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4559 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4560 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4561 if (version == JNI_VERSION_9) return JNI_TRUE;
4562 if (version == JNI_VERSION_10) return JNI_TRUE;
4563 return JNI_FALSE;
4564 }
4565
4566
4567 void Threads::add(JavaThread* p, bool force_daemon) {
4568 // The threads lock must be owned at this point
4569 assert(Threads_lock->owned_by_self(), "must have threads lock");
4570
4571 BarrierSet::barrier_set()->on_thread_attach(p);
4572
4573 // Once a JavaThread is added to the Threads list, smr_delete() has
4574 // to be used to delete it. Otherwise we can just delete it directly.
4575 p->set_on_thread_list();
4576
4577 _number_of_threads++;
4578 oop threadObj = p->threadObj();
4579 bool daemon = true;
4580 // Bootstrapping problem: threadObj can be null for initial
4581 // JavaThread (or for threads attached via JNI)
4582 if ((!force_daemon) && !is_daemon((threadObj))) {
4583 _number_of_non_daemon_threads++;
4584 daemon = false;
4585 }
4586
4587 ThreadService::add_thread(p, daemon);
4588
4589 // Maintain fast thread list
4590 ThreadsSMRSupport::add_thread(p);
4591
4592 // Possible GC point.
4593 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4594 }
4595
4596 void Threads::remove(JavaThread* p, bool is_daemon) {
4597
4598 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4599 ObjectSynchronizer::om_flush(p);
4600
4601 // Extra scope needed for Thread_lock, so we can check
4602 // that we do not remove thread without safepoint code notice
4603 { MonitorLocker ml(Threads_lock);
4604
4605 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4606
4607 // Maintain fast thread list
4608 ThreadsSMRSupport::remove_thread(p);
4609
4610 _number_of_threads--;
4611 if (!is_daemon) {
4612 _number_of_non_daemon_threads--;
4613
4614 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4615 // on destroy_vm will wake up.
4616 if (number_of_non_daemon_threads() == 1) {
4617 ml.notify_all();
4618 }
4619 }
4620 ThreadService::remove_thread(p, is_daemon);
4621
4622 // Make sure that safepoint code disregard this thread. This is needed since
4623 // the thread might mess around with locks after this point. This can cause it
4624 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4625 // of this thread since it is removed from the queue.
4626 p->set_terminated_value();
4627 } // unlock Threads_lock
4628
4629 // Since Events::log uses a lock, we grab it outside the Threads_lock
4630 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4631 }
4632
4633 // Operations on the Threads list for GC. These are not explicitly locked,
4634 // but the garbage collector must provide a safe context for them to run.
4635 // In particular, these things should never be called when the Threads_lock
4636 // is held by some other thread. (Note: the Safepoint abstraction also
4637 // uses the Threads_lock to guarantee this property. It also makes sure that
4638 // all threads gets blocked when exiting or starting).
4639
4640 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4641 ALL_JAVA_THREADS(p) {
4642 p->oops_do(f, cf);
4643 }
4644 VMThread::vm_thread()->oops_do(f, cf);
4645 }
4646
4647 void Threads::change_thread_claim_token() {
4648 if (++_thread_claim_token == 0) {
4649 // On overflow of the token counter, there is a risk of future
4650 // collisions between a new global token value and a stale token
4651 // for a thread, because not all iterations visit all threads.
4652 // (Though it's pretty much a theoretical concern for non-trivial
4653 // token counter sizes.) To deal with the possibility, reset all
4654 // the thread tokens to zero on global token overflow.
4655 struct ResetClaims : public ThreadClosure {
4656 virtual void do_thread(Thread* t) {
4657 t->claim_threads_do(false, 0);
4658 }
4659 } reset_claims;
4660 Threads::threads_do(&reset_claims);
4661 // On overflow, update the global token to non-zero, to
4662 // avoid the special "never claimed" initial thread value.
4663 _thread_claim_token = 1;
4664 }
4665 }
4666
4667 #ifdef ASSERT
4668 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4669 const uintx token = t->threads_do_token();
4670 assert(token == expected,
4671 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4672 UINTX_FORMAT, kind, p2i(t), token, expected);
4673 }
4674
4675 void Threads::assert_all_threads_claimed() {
4676 ALL_JAVA_THREADS(p) {
4677 assert_thread_claimed("Thread", p, _thread_claim_token);
4678 }
4679 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4680 }
4681 #endif // ASSERT
4682
4683 class ParallelOopsDoThreadClosure : public ThreadClosure {
4684 private:
4685 OopClosure* _f;
4686 CodeBlobClosure* _cf;
4687 public:
4688 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4689 void do_thread(Thread* t) {
4690 t->oops_do(_f, _cf);
4691 }
4692 };
4693
4694 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4695 ParallelOopsDoThreadClosure tc(f, cf);
4696 possibly_parallel_threads_do(is_par, &tc);
4697 }
4698
4699 void Threads::nmethods_do(CodeBlobClosure* cf) {
4700 ALL_JAVA_THREADS(p) {
4701 // This is used by the code cache sweeper to mark nmethods that are active
4702 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4703 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4704 if(!p->is_Code_cache_sweeper_thread()) {
4705 p->nmethods_do(cf);
4706 }
4707 }
4708 }
4709
4710 void Threads::metadata_do(MetadataClosure* f) {
4711 ALL_JAVA_THREADS(p) {
4712 p->metadata_do(f);
4713 }
4714 }
4715
4716 class ThreadHandlesClosure : public ThreadClosure {
4717 void (*_f)(Metadata*);
4718 public:
4719 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4720 virtual void do_thread(Thread* thread) {
4721 thread->metadata_handles_do(_f);
4722 }
4723 };
4724
4725 void Threads::metadata_handles_do(void f(Metadata*)) {
4726 // Only walk the Handles in Thread.
4727 ThreadHandlesClosure handles_closure(f);
4728 threads_do(&handles_closure);
4729 }
4730
4731 // Get count Java threads that are waiting to enter the specified monitor.
4732 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4733 int count,
4734 address monitor) {
4735 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4736
4737 int i = 0;
4738 DO_JAVA_THREADS(t_list, p) {
4739 if (!p->can_call_java()) continue;
4740
4741 // The first stage of async deflation does not affect any field
4742 // used by this comparison so the ObjectMonitor* is usable here.
4743 address pending = (address)p->current_pending_monitor();
4744 if (pending == monitor) { // found a match
4745 if (i < count) result->append(p); // save the first count matches
4746 i++;
4747 }
4748 }
4749
4750 return result;
4751 }
4752
4753
4754 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4755 address owner) {
4756 // NULL owner means not locked so we can skip the search
4757 if (owner == NULL) return NULL;
4758
4759 DO_JAVA_THREADS(t_list, p) {
4760 // first, see if owner is the address of a Java thread
4761 if (owner == (address)p) return p;
4762 }
4763
4764 // Cannot assert on lack of success here since this function may be
4765 // used by code that is trying to report useful problem information
4766 // like deadlock detection.
4767 if (UseHeavyMonitors) return NULL;
4768
4769 // If we didn't find a matching Java thread and we didn't force use of
4770 // heavyweight monitors, then the owner is the stack address of the
4771 // Lock Word in the owning Java thread's stack.
4772 //
4773 JavaThread* the_owner = NULL;
4774 DO_JAVA_THREADS(t_list, q) {
4775 if (q->is_lock_owned(owner)) {
4776 the_owner = q;
4777 break;
4778 }
4779 }
4780
4781 // cannot assert on lack of success here; see above comment
4782 return the_owner;
4783 }
4784
4785 class PrintOnClosure : public ThreadClosure {
4786 private:
4787 outputStream* _st;
4788
4789 public:
4790 PrintOnClosure(outputStream* st) :
4791 _st(st) {}
4792
4793 virtual void do_thread(Thread* thread) {
4794 if (thread != NULL) {
4795 thread->print_on(_st);
4796 _st->cr();
4797 }
4798 }
4799 };
4800
4801 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4802 void Threads::print_on(outputStream* st, bool print_stacks,
4803 bool internal_format, bool print_concurrent_locks,
4804 bool print_extended_info) {
4805 char buf[32];
4806 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4807
4808 st->print_cr("Full thread dump %s (%s %s):",
4809 VM_Version::vm_name(),
4810 VM_Version::vm_release(),
4811 VM_Version::vm_info_string());
4812 st->cr();
4813
4814 #if INCLUDE_SERVICES
4815 // Dump concurrent locks
4816 ConcurrentLocksDump concurrent_locks;
4817 if (print_concurrent_locks) {
4818 concurrent_locks.dump_at_safepoint();
4819 }
4820 #endif // INCLUDE_SERVICES
4821
4822 ThreadsSMRSupport::print_info_on(st);
4823 st->cr();
4824
4825 ALL_JAVA_THREADS(p) {
4826 ResourceMark rm;
4827 p->print_on(st, print_extended_info);
4828 if (print_stacks) {
4829 if (internal_format) {
4830 p->trace_stack();
4831 } else {
4832 p->print_stack_on(st);
4833 }
4834 }
4835 st->cr();
4836 #if INCLUDE_SERVICES
4837 if (print_concurrent_locks) {
4838 concurrent_locks.print_locks_on(p, st);
4839 }
4840 #endif // INCLUDE_SERVICES
4841 }
4842
4843 PrintOnClosure cl(st);
4844 cl.do_thread(VMThread::vm_thread());
4845 Universe::heap()->gc_threads_do(&cl);
4846 cl.do_thread(WatcherThread::watcher_thread());
4847
4848 st->flush();
4849 }
4850
4851 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4852 int buflen, bool* found_current) {
4853 if (this_thread != NULL) {
4854 bool is_current = (current == this_thread);
4855 *found_current = *found_current || is_current;
4856 st->print("%s", is_current ? "=>" : " ");
4857
4858 st->print(PTR_FORMAT, p2i(this_thread));
4859 st->print(" ");
4860 this_thread->print_on_error(st, buf, buflen);
4861 st->cr();
4862 }
4863 }
4864
4865 class PrintOnErrorClosure : public ThreadClosure {
4866 outputStream* _st;
4867 Thread* _current;
4868 char* _buf;
4869 int _buflen;
4870 bool* _found_current;
4871 public:
4872 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4873 int buflen, bool* found_current) :
4874 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4875
4876 virtual void do_thread(Thread* thread) {
4877 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4878 }
4879 };
4880
4881 // Threads::print_on_error() is called by fatal error handler. It's possible
4882 // that VM is not at safepoint and/or current thread is inside signal handler.
4883 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4884 // memory (even in resource area), it might deadlock the error handler.
4885 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4886 int buflen) {
4887 ThreadsSMRSupport::print_info_on(st);
4888 st->cr();
4889
4890 bool found_current = false;
4891 st->print_cr("Java Threads: ( => current thread )");
4892 ALL_JAVA_THREADS(thread) {
4893 print_on_error(thread, st, current, buf, buflen, &found_current);
4894 }
4895 st->cr();
4896
4897 st->print_cr("Other Threads:");
4898 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4899 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4900
4901 if (Universe::heap() != NULL) {
4902 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4903 Universe::heap()->gc_threads_do(&print_closure);
4904 }
4905
4906 if (!found_current) {
4907 st->cr();
4908 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4909 current->print_on_error(st, buf, buflen);
4910 st->cr();
4911 }
4912 st->cr();
4913
4914 st->print_cr("Threads with active compile tasks:");
4915 print_threads_compiling(st, buf, buflen);
4916 }
4917
4918 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4919 ALL_JAVA_THREADS(thread) {
4920 if (thread->is_Compiler_thread()) {
4921 CompilerThread* ct = (CompilerThread*) thread;
4922
4923 // Keep task in local variable for NULL check.
4924 // ct->_task might be set to NULL by concurring compiler thread
4925 // because it completed the compilation. The task is never freed,
4926 // though, just returned to a free list.
4927 CompileTask* task = ct->task();
4928 if (task != NULL) {
4929 thread->print_name_on_error(st, buf, buflen);
4930 st->print(" ");
4931 task->print(st, NULL, short_form, true);
4932 }
4933 }
4934 }
4935 }
4936
4937
4938 // Internal SpinLock and Mutex
4939 // Based on ParkEvent
4940
4941 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4942 //
4943 // We employ SpinLocks _only for low-contention, fixed-length
4944 // short-duration critical sections where we're concerned
4945 // about native mutex_t or HotSpot Mutex:: latency.
4946 // The mux construct provides a spin-then-block mutual exclusion
4947 // mechanism.
4948 //
4949 // Testing has shown that contention on the ListLock guarding gFreeList
4950 // is common. If we implement ListLock as a simple SpinLock it's common
4951 // for the JVM to devolve to yielding with little progress. This is true
4952 // despite the fact that the critical sections protected by ListLock are
4953 // extremely short.
4954 //
4955 // TODO-FIXME: ListLock should be of type SpinLock.
4956 // We should make this a 1st-class type, integrated into the lock
4957 // hierarchy as leaf-locks. Critically, the SpinLock structure
4958 // should have sufficient padding to avoid false-sharing and excessive
4959 // cache-coherency traffic.
4960
4961
4962 typedef volatile int SpinLockT;
4963
4964 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4965 if (Atomic::cmpxchg(adr, 0, 1) == 0) {
4966 return; // normal fast-path return
4967 }
4968
4969 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4970 int ctr = 0;
4971 int Yields = 0;
4972 for (;;) {
4973 while (*adr != 0) {
4974 ++ctr;
4975 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4976 if (Yields > 5) {
4977 os::naked_short_sleep(1);
4978 } else {
4979 os::naked_yield();
4980 ++Yields;
4981 }
4982 } else {
4983 SpinPause();
4984 }
4985 }
4986 if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
4987 }
4988 }
4989
4990 void Thread::SpinRelease(volatile int * adr) {
4991 assert(*adr != 0, "invariant");
4992 OrderAccess::fence(); // guarantee at least release consistency.
4993 // Roach-motel semantics.
4994 // It's safe if subsequent LDs and STs float "up" into the critical section,
4995 // but prior LDs and STs within the critical section can't be allowed
4996 // to reorder or float past the ST that releases the lock.
4997 // Loads and stores in the critical section - which appear in program
4998 // order before the store that releases the lock - must also appear
4999 // before the store that releases the lock in memory visibility order.
5000 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
5001 // the ST of 0 into the lock-word which releases the lock, so fence
5002 // more than covers this on all platforms.
5003 *adr = 0;
5004 }
5005
5006 // muxAcquire and muxRelease:
5007 //
5008 // * muxAcquire and muxRelease support a single-word lock-word construct.
5009 // The LSB of the word is set IFF the lock is held.
5010 // The remainder of the word points to the head of a singly-linked list
5011 // of threads blocked on the lock.
5012 //
5013 // * The current implementation of muxAcquire-muxRelease uses its own
5014 // dedicated Thread._MuxEvent instance. If we're interested in
5015 // minimizing the peak number of extant ParkEvent instances then
5016 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5017 // as certain invariants were satisfied. Specifically, care would need
5018 // to be taken with regards to consuming unpark() "permits".
5019 // A safe rule of thumb is that a thread would never call muxAcquire()
5020 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5021 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
5022 // consume an unpark() permit intended for monitorenter, for instance.
5023 // One way around this would be to widen the restricted-range semaphore
5024 // implemented in park(). Another alternative would be to provide
5025 // multiple instances of the PlatformEvent() for each thread. One
5026 // instance would be dedicated to muxAcquire-muxRelease, for instance.
5027 //
5028 // * Usage:
5029 // -- Only as leaf locks
5030 // -- for short-term locking only as muxAcquire does not perform
5031 // thread state transitions.
5032 //
5033 // Alternatives:
5034 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
5035 // but with parking or spin-then-park instead of pure spinning.
5036 // * Use Taura-Oyama-Yonenzawa locks.
5037 // * It's possible to construct a 1-0 lock if we encode the lockword as
5038 // (List,LockByte). Acquire will CAS the full lockword while Release
5039 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
5040 // acquiring threads use timers (ParkTimed) to detect and recover from
5041 // the stranding window. Thread/Node structures must be aligned on 256-byte
5042 // boundaries by using placement-new.
5043 // * Augment MCS with advisory back-link fields maintained with CAS().
5044 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5045 // The validity of the backlinks must be ratified before we trust the value.
5046 // If the backlinks are invalid the exiting thread must back-track through the
5047 // the forward links, which are always trustworthy.
5048 // * Add a successor indication. The LockWord is currently encoded as
5049 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
5050 // to provide the usual futile-wakeup optimization.
5051 // See RTStt for details.
5052 //
5053
5054
5055 const intptr_t LOCKBIT = 1;
5056
5057 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5058 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT);
5059 if (w == 0) return;
5060 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5061 return;
5062 }
5063
5064 ParkEvent * const Self = Thread::current()->_MuxEvent;
5065 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5066 for (;;) {
5067 int its = (os::is_MP() ? 100 : 0) + 1;
5068
5069 // Optional spin phase: spin-then-park strategy
5070 while (--its >= 0) {
5071 w = *Lock;
5072 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5073 return;
5074 }
5075 }
5076
5077 Self->reset();
5078 Self->OnList = intptr_t(Lock);
5079 // The following fence() isn't _strictly necessary as the subsequent
5080 // CAS() both serializes execution and ratifies the fetched *Lock value.
5081 OrderAccess::fence();
5082 for (;;) {
5083 w = *Lock;
5084 if ((w & LOCKBIT) == 0) {
5085 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5086 Self->OnList = 0; // hygiene - allows stronger asserts
5087 return;
5088 }
5089 continue; // Interference -- *Lock changed -- Just retry
5090 }
5091 assert(w & LOCKBIT, "invariant");
5092 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5093 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break;
5094 }
5095
5096 while (Self->OnList != 0) {
5097 Self->park();
5098 }
5099 }
5100 }
5101
5102 // Release() must extract a successor from the list and then wake that thread.
5103 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5104 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5105 // Release() would :
5106 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5107 // (B) Extract a successor from the private list "in-hand"
5108 // (C) attempt to CAS() the residual back into *Lock over null.
5109 // If there were any newly arrived threads and the CAS() would fail.
5110 // In that case Release() would detach the RATs, re-merge the list in-hand
5111 // with the RATs and repeat as needed. Alternately, Release() might
5112 // detach and extract a successor, but then pass the residual list to the wakee.
5113 // The wakee would be responsible for reattaching and remerging before it
5114 // competed for the lock.
5115 //
5116 // Both "pop" and DMR are immune from ABA corruption -- there can be
5117 // multiple concurrent pushers, but only one popper or detacher.
5118 // This implementation pops from the head of the list. This is unfair,
5119 // but tends to provide excellent throughput as hot threads remain hot.
5120 // (We wake recently run threads first).
5121 //
5122 // All paths through muxRelease() will execute a CAS.
5123 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5124 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5125 // executed within the critical section are complete and globally visible before the
5126 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5127 void Thread::muxRelease(volatile intptr_t * Lock) {
5128 for (;;) {
5129 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0);
5130 assert(w & LOCKBIT, "invariant");
5131 if (w == LOCKBIT) return;
5132 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5133 assert(List != NULL, "invariant");
5134 assert(List->OnList == intptr_t(Lock), "invariant");
5135 ParkEvent * const nxt = List->ListNext;
5136 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5137
5138 // The following CAS() releases the lock and pops the head element.
5139 // The CAS() also ratifies the previously fetched lock-word value.
5140 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) {
5141 continue;
5142 }
5143 List->OnList = 0;
5144 OrderAccess::fence();
5145 List->unpark();
5146 return;
5147 }
5148 }
5149
5150
5151 void Threads::verify() {
5152 ALL_JAVA_THREADS(p) {
5153 p->verify();
5154 }
5155 VMThread* thread = VMThread::vm_thread();
5156 if (thread != NULL) thread->verify();
5157 }