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