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