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