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