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