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 if (_name != NULL) {
1330 FREE_C_HEAP_ARRAY(char, _name);
1331 _name = NULL;
1332 }
1333 }
1334
1335 void NamedThread::set_name(const char* format, ...) {
1336 guarantee(_name == NULL, "Only get to set name once.");
1337 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1338 guarantee(_name != NULL, "alloc failure");
1339 va_list ap;
1340 va_start(ap, format);
1341 jio_vsnprintf(_name, max_name_len, format, ap);
1342 va_end(ap);
1343 }
1344
1345 void NamedThread::print_on(outputStream* st) const {
1346 st->print("\"%s\" ", name());
1347 Thread::print_on(st);
1348 st->cr();
1349 }
1350
1351
1352 // ======= WatcherThread ========
1353
1354 // The watcher thread exists to simulate timer interrupts. It should
1355 // be replaced by an abstraction over whatever native support for
1356 // timer interrupts exists on the platform.
1357
1358 WatcherThread* WatcherThread::_watcher_thread = NULL;
1359 bool WatcherThread::_startable = false;
1360 volatile bool WatcherThread::_should_terminate = false;
1361
1362 WatcherThread::WatcherThread() : NonJavaThread() {
1363 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1364 if (os::create_thread(this, os::watcher_thread)) {
1365 _watcher_thread = this;
1366
1367 // Set the watcher thread to the highest OS priority which should not be
1368 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1369 // is created. The only normal thread using this priority is the reference
1370 // handler thread, which runs for very short intervals only.
1371 // If the VMThread's priority is not lower than the WatcherThread profiling
1372 // will be inaccurate.
1373 os::set_priority(this, MaxPriority);
1374 if (!DisableStartThread) {
1375 os::start_thread(this);
1376 }
1377 }
1378 }
1379
1380 int WatcherThread::sleep() const {
1381 // The WatcherThread does not participate in the safepoint protocol
1382 // for the PeriodicTask_lock because it is not a JavaThread.
1383 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1384
1385 if (_should_terminate) {
1386 // check for termination before we do any housekeeping or wait
1387 return 0; // we did not sleep.
1388 }
1389
1390 // remaining will be zero if there are no tasks,
1391 // causing the WatcherThread to sleep until a task is
1392 // enrolled
1393 int remaining = PeriodicTask::time_to_wait();
1394 int time_slept = 0;
1395
1396 // we expect this to timeout - we only ever get unparked when
1397 // we should terminate or when a new task has been enrolled
1398 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1399
1400 jlong time_before_loop = os::javaTimeNanos();
1401
1402 while (true) {
1403 bool timedout = ml.wait(remaining);
1404 jlong now = os::javaTimeNanos();
1405
1406 if (remaining == 0) {
1407 // if we didn't have any tasks we could have waited for a long time
1408 // consider the time_slept zero and reset time_before_loop
1409 time_slept = 0;
1410 time_before_loop = now;
1411 } else {
1412 // need to recalculate since we might have new tasks in _tasks
1413 time_slept = (int) ((now - time_before_loop) / 1000000);
1414 }
1415
1416 // Change to task list or spurious wakeup of some kind
1417 if (timedout || _should_terminate) {
1418 break;
1419 }
1420
1421 remaining = PeriodicTask::time_to_wait();
1422 if (remaining == 0) {
1423 // Last task was just disenrolled so loop around and wait until
1424 // another task gets enrolled
1425 continue;
1426 }
1427
1428 remaining -= time_slept;
1429 if (remaining <= 0) {
1430 break;
1431 }
1432 }
1433
1434 return time_slept;
1435 }
1436
1437 void WatcherThread::run() {
1438 assert(this == watcher_thread(), "just checking");
1439
1440 this->set_active_handles(JNIHandleBlock::allocate_block());
1441 while (true) {
1442 assert(watcher_thread() == Thread::current(), "thread consistency check");
1443 assert(watcher_thread() == this, "thread consistency check");
1444
1445 // Calculate how long it'll be until the next PeriodicTask work
1446 // should be done, and sleep that amount of time.
1447 int time_waited = sleep();
1448
1449 if (VMError::is_error_reported()) {
1450 // A fatal error has happened, the error handler(VMError::report_and_die)
1451 // should abort JVM after creating an error log file. However in some
1452 // rare cases, the error handler itself might deadlock. Here periodically
1453 // check for error reporting timeouts, and if it happens, just proceed to
1454 // abort the VM.
1455
1456 // This code is in WatcherThread because WatcherThread wakes up
1457 // periodically so the fatal error handler doesn't need to do anything;
1458 // also because the WatcherThread is less likely to crash than other
1459 // threads.
1460
1461 for (;;) {
1462 // Note: we use naked sleep in this loop because we want to avoid using
1463 // any kind of VM infrastructure which may be broken at this point.
1464 if (VMError::check_timeout()) {
1465 // We hit error reporting timeout. Error reporting was interrupted and
1466 // will be wrapping things up now (closing files etc). Give it some more
1467 // time, then quit the VM.
1468 os::naked_short_sleep(200);
1469 // Print a message to stderr.
1470 fdStream err(defaultStream::output_fd());
1471 err.print_raw_cr("# [ timer expired, abort... ]");
1472 // skip atexit/vm_exit/vm_abort hooks
1473 os::die();
1474 }
1475
1476 // Wait a second, then recheck for timeout.
1477 os::naked_short_sleep(999);
1478 }
1479 }
1480
1481 if (_should_terminate) {
1482 // check for termination before posting the next tick
1483 break;
1484 }
1485
1486 PeriodicTask::real_time_tick(time_waited);
1487 }
1488
1489 // Signal that it is terminated
1490 {
1491 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1492 _watcher_thread = NULL;
1493 Terminator_lock->notify_all();
1494 }
1495 }
1496
1497 void WatcherThread::start() {
1498 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1499
1500 if (watcher_thread() == NULL && _startable) {
1501 _should_terminate = false;
1502 // Create the single instance of WatcherThread
1503 new WatcherThread();
1504 }
1505 }
1506
1507 void WatcherThread::make_startable() {
1508 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1509 _startable = true;
1510 }
1511
1512 void WatcherThread::stop() {
1513 {
1514 // Follow normal safepoint aware lock enter protocol since the
1515 // WatcherThread is stopped by another JavaThread.
1516 MutexLocker ml(PeriodicTask_lock);
1517 _should_terminate = true;
1518
1519 WatcherThread* watcher = watcher_thread();
1520 if (watcher != NULL) {
1521 // unpark the WatcherThread so it can see that it should terminate
1522 watcher->unpark();
1523 }
1524 }
1525
1526 MonitorLocker mu(Terminator_lock);
1527
1528 while (watcher_thread() != NULL) {
1529 // This wait should make safepoint checks, wait without a timeout,
1530 // and wait as a suspend-equivalent condition.
1531 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1532 }
1533 }
1534
1535 void WatcherThread::unpark() {
1536 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1537 PeriodicTask_lock->notify();
1538 }
1539
1540 void WatcherThread::print_on(outputStream* st) const {
1541 st->print("\"%s\" ", name());
1542 Thread::print_on(st);
1543 st->cr();
1544 }
1545
1546 // ======= JavaThread ========
1547
1548 #if INCLUDE_JVMCI
1549
1550 jlong* JavaThread::_jvmci_old_thread_counters;
1551
1552 bool jvmci_counters_include(JavaThread* thread) {
1553 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1554 }
1555
1556 void JavaThread::collect_counters(jlong* array, int length) {
1557 assert(length == JVMCICounterSize, "wrong value");
1558 for (int i = 0; i < length; i++) {
1559 array[i] = _jvmci_old_thread_counters[i];
1560 }
1561 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1562 if (jvmci_counters_include(tp)) {
1563 for (int i = 0; i < length; i++) {
1564 array[i] += tp->_jvmci_counters[i];
1565 }
1566 }
1567 }
1568 }
1569
1570 // Attempt to enlarge the array for per thread counters.
1571 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1572 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1573 if (new_counters == NULL) {
1574 return NULL;
1575 }
1576 if (old_counters == NULL) {
1577 old_counters = new_counters;
1578 memset(old_counters, 0, sizeof(jlong) * new_size);
1579 } else {
1580 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1581 new_counters[i] = old_counters[i];
1582 }
1583 if (new_size > current_size) {
1584 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1585 }
1586 FREE_C_HEAP_ARRAY(jlong, old_counters);
1587 }
1588 return new_counters;
1589 }
1590
1591 // Attempt to enlarge the array for per thread counters.
1592 bool JavaThread::resize_counters(int current_size, int new_size) {
1593 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1594 if (new_counters == NULL) {
1595 return false;
1596 } else {
1597 _jvmci_counters = new_counters;
1598 return true;
1599 }
1600 }
1601
1602 class VM_JVMCIResizeCounters : public VM_Operation {
1603 private:
1604 int _new_size;
1605 bool _failed;
1606
1607 public:
1608 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1609 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1610 bool allow_nested_vm_operations() const { return true; }
1611 void doit() {
1612 // Resize the old thread counters array
1613 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1614 if (new_counters == NULL) {
1615 _failed = true;
1616 return;
1617 } else {
1618 JavaThread::_jvmci_old_thread_counters = new_counters;
1619 }
1620
1621 // Now resize each threads array
1622 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1623 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1624 _failed = true;
1625 break;
1626 }
1627 }
1628 if (!_failed) {
1629 JVMCICounterSize = _new_size;
1630 }
1631 }
1632
1633 bool failed() { return _failed; }
1634 };
1635
1636 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1637 VM_JVMCIResizeCounters op(new_size);
1638 VMThread::execute(&op);
1639 return !op.failed();
1640 }
1641
1642 #endif // INCLUDE_JVMCI
1643
1644 // A JavaThread is a normal Java thread
1645
1646 void JavaThread::initialize() {
1647 // Initialize fields
1648
1649 set_saved_exception_pc(NULL);
1650 set_threadObj(NULL);
1651 _anchor.clear();
1652 set_entry_point(NULL);
1653 set_jni_functions(jni_functions());
1654 set_callee_target(NULL);
1655 set_vm_result(NULL);
1656 set_vm_result_2(NULL);
1657 set_vframe_array_head(NULL);
1658 set_vframe_array_last(NULL);
1659 set_deferred_locals(NULL);
1660 set_deopt_mark(NULL);
1661 set_deopt_compiled_method(NULL);
1662 set_monitor_chunks(NULL);
1663 _on_thread_list = false;
1664 set_thread_state(_thread_new);
1665 _terminated = _not_terminated;
1666 _array_for_gc = NULL;
1667 _suspend_equivalent = false;
1668 _in_deopt_handler = 0;
1669 _doing_unsafe_access = false;
1670 _stack_guard_state = stack_guard_unused;
1671 #if INCLUDE_JVMCI
1672 _pending_monitorenter = false;
1673 _pending_deoptimization = -1;
1674 _pending_failed_speculation = 0;
1675 _pending_transfer_to_interpreter = false;
1676 _in_retryable_allocation = false;
1677 _jvmci._alternate_call_target = NULL;
1678 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1679 _jvmci_counters = NULL;
1680 if (JVMCICounterSize > 0) {
1681 resize_counters(0, (int) JVMCICounterSize);
1682 }
1683 #endif // INCLUDE_JVMCI
1684 _reserved_stack_activation = NULL; // stack base not known yet
1685 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1686 _exception_pc = 0;
1687 _exception_handler_pc = 0;
1688 _is_method_handle_return = 0;
1689 _jvmti_thread_state= NULL;
1690 _should_post_on_exceptions_flag = JNI_FALSE;
1691 _interp_only_mode = 0;
1692 _special_runtime_exit_condition = _no_async_condition;
1693 _pending_async_exception = NULL;
1694 _thread_stat = NULL;
1695 _thread_stat = new ThreadStatistics();
1696 _jni_active_critical = 0;
1697 _pending_jni_exception_check_fn = NULL;
1698 _do_not_unlock_if_synchronized = false;
1699 _cached_monitor_info = NULL;
1700 _parker = Parker::Allocate(this);
1701 _SleepEvent = ParkEvent::Allocate(this);
1702 // Setup safepoint state info for this thread
1703 ThreadSafepointState::create(this);
1704
1705 debug_only(_java_call_counter = 0);
1706
1707 // JVMTI PopFrame support
1708 _popframe_condition = popframe_inactive;
1709 _popframe_preserved_args = NULL;
1710 _popframe_preserved_args_size = 0;
1711 _frames_to_pop_failed_realloc = 0;
1712
1713 if (SafepointMechanism::uses_thread_local_poll()) {
1714 SafepointMechanism::initialize_header(this);
1715 }
1716
1717 _class_to_be_initialized = NULL;
1718
1719 pd_initialize();
1720 }
1721
1722 JavaThread::JavaThread(bool is_attaching_via_jni) :
1723 Thread() {
1724 initialize();
1725 if (is_attaching_via_jni) {
1726 _jni_attach_state = _attaching_via_jni;
1727 } else {
1728 _jni_attach_state = _not_attaching_via_jni;
1729 }
1730 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1731 }
1732
1733 bool JavaThread::reguard_stack(address cur_sp) {
1734 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1735 && _stack_guard_state != stack_guard_reserved_disabled) {
1736 return true; // Stack already guarded or guard pages not needed.
1737 }
1738
1739 if (register_stack_overflow()) {
1740 // For those architectures which have separate register and
1741 // memory stacks, we must check the register stack to see if
1742 // it has overflowed.
1743 return false;
1744 }
1745
1746 // Java code never executes within the yellow zone: the latter is only
1747 // there to provoke an exception during stack banging. If java code
1748 // is executing there, either StackShadowPages should be larger, or
1749 // some exception code in c1, c2 or the interpreter isn't unwinding
1750 // when it should.
1751 guarantee(cur_sp > stack_reserved_zone_base(),
1752 "not enough space to reguard - increase StackShadowPages");
1753 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1754 enable_stack_yellow_reserved_zone();
1755 if (reserved_stack_activation() != stack_base()) {
1756 set_reserved_stack_activation(stack_base());
1757 }
1758 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1759 set_reserved_stack_activation(stack_base());
1760 enable_stack_reserved_zone();
1761 }
1762 return true;
1763 }
1764
1765 bool JavaThread::reguard_stack(void) {
1766 return reguard_stack(os::current_stack_pointer());
1767 }
1768
1769
1770 void JavaThread::block_if_vm_exited() {
1771 if (_terminated == _vm_exited) {
1772 // _vm_exited is set at safepoint, and Threads_lock is never released
1773 // we will block here forever
1774 Threads_lock->lock();
1775 ShouldNotReachHere();
1776 }
1777 }
1778
1779
1780 // Remove this ifdef when C1 is ported to the compiler interface.
1781 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1782 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1783
1784 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1785 Thread() {
1786 initialize();
1787 _jni_attach_state = _not_attaching_via_jni;
1788 set_entry_point(entry_point);
1789 // Create the native thread itself.
1790 // %note runtime_23
1791 os::ThreadType thr_type = os::java_thread;
1792 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1793 os::java_thread;
1794 os::create_thread(this, thr_type, stack_sz);
1795 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1796 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1797 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1798 // the exception consists of creating the exception object & initializing it, initialization
1799 // will leave the VM via a JavaCall and then all locks must be unlocked).
1800 //
1801 // The thread is still suspended when we reach here. Thread must be explicit started
1802 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1803 // by calling Threads:add. The reason why this is not done here, is because the thread
1804 // object must be fully initialized (take a look at JVM_Start)
1805 }
1806
1807 JavaThread::~JavaThread() {
1808
1809 // JSR166 -- return the parker to the free list
1810 Parker::Release(_parker);
1811 _parker = NULL;
1812
1813 // Return the sleep event to the free list
1814 ParkEvent::Release(_SleepEvent);
1815 _SleepEvent = NULL;
1816
1817 // Free any remaining previous UnrollBlock
1818 vframeArray* old_array = vframe_array_last();
1819
1820 if (old_array != NULL) {
1821 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1822 old_array->set_unroll_block(NULL);
1823 delete old_info;
1824 delete old_array;
1825 }
1826
1827 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1828 if (deferred != NULL) {
1829 // This can only happen if thread is destroyed before deoptimization occurs.
1830 assert(deferred->length() != 0, "empty array!");
1831 do {
1832 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1833 deferred->remove_at(0);
1834 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1835 delete dlv;
1836 } while (deferred->length() != 0);
1837 delete deferred;
1838 }
1839
1840 // All Java related clean up happens in exit
1841 ThreadSafepointState::destroy(this);
1842 if (_thread_stat != NULL) delete _thread_stat;
1843
1844 #if INCLUDE_JVMCI
1845 if (JVMCICounterSize > 0) {
1846 if (jvmci_counters_include(this)) {
1847 for (int i = 0; i < JVMCICounterSize; i++) {
1848 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1849 }
1850 }
1851 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1852 }
1853 #endif // INCLUDE_JVMCI
1854 }
1855
1856
1857 // First JavaThread specific code executed by a new Java thread.
1858 void JavaThread::pre_run() {
1859 // empty - see comments in run()
1860 }
1861
1862 // The main routine called by a new Java thread. This isn't overridden
1863 // by subclasses, instead different subclasses define a different "entry_point"
1864 // which defines the actual logic for that kind of thread.
1865 void JavaThread::run() {
1866 // initialize thread-local alloc buffer related fields
1867 this->initialize_tlab();
1868
1869 // Used to test validity of stack trace backs.
1870 // This can't be moved into pre_run() else we invalidate
1871 // the requirement that thread_main_inner is lower on
1872 // the stack. Consequently all the initialization logic
1873 // stays here in run() rather than pre_run().
1874 this->record_base_of_stack_pointer();
1875
1876 this->create_stack_guard_pages();
1877
1878 this->cache_global_variables();
1879
1880 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1881 // in the VM. Change thread state from _thread_new to _thread_in_vm
1882 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1883 // Before a thread is on the threads list it is always safe, so after leaving the
1884 // _thread_new we should emit a instruction barrier. The distance to modified code
1885 // from here is probably far enough, but this is consistent and safe.
1886 OrderAccess::cross_modify_fence();
1887
1888 assert(JavaThread::current() == this, "sanity check");
1889 assert(!Thread::current()->owns_locks(), "sanity check");
1890
1891 DTRACE_THREAD_PROBE(start, this);
1892
1893 // This operation might block. We call that after all safepoint checks for a new thread has
1894 // been completed.
1895 this->set_active_handles(JNIHandleBlock::allocate_block());
1896
1897 if (JvmtiExport::should_post_thread_life()) {
1898 JvmtiExport::post_thread_start(this);
1899
1900 }
1901
1902 // We call another function to do the rest so we are sure that the stack addresses used
1903 // from there will be lower than the stack base just computed.
1904 thread_main_inner();
1905 }
1906
1907 void JavaThread::thread_main_inner() {
1908 assert(JavaThread::current() == this, "sanity check");
1909 assert(this->threadObj() != NULL, "just checking");
1910
1911 // Execute thread entry point unless this thread has a pending exception
1912 // or has been stopped before starting.
1913 // Note: Due to JVM_StopThread we can have pending exceptions already!
1914 if (!this->has_pending_exception() &&
1915 !java_lang_Thread::is_stillborn(this->threadObj())) {
1916 {
1917 ResourceMark rm(this);
1918 this->set_native_thread_name(this->get_thread_name());
1919 }
1920 HandleMark hm(this);
1921 this->entry_point()(this, this);
1922 }
1923
1924 DTRACE_THREAD_PROBE(stop, this);
1925
1926 // Cleanup is handled in post_run()
1927 }
1928
1929 // Shared teardown for all JavaThreads
1930 void JavaThread::post_run() {
1931 this->exit(false);
1932 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1933 // for any shared tear-down.
1934 this->smr_delete();
1935 }
1936
1937 static void ensure_join(JavaThread* thread) {
1938 // We do not need to grab the Threads_lock, since we are operating on ourself.
1939 Handle threadObj(thread, thread->threadObj());
1940 assert(threadObj.not_null(), "java thread object must exist");
1941 ObjectLocker lock(threadObj, thread);
1942 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1943 thread->clear_pending_exception();
1944 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1945 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1946 // Clear the native thread instance - this makes isAlive return false and allows the join()
1947 // to complete once we've done the notify_all below
1948 java_lang_Thread::set_thread(threadObj(), NULL);
1949 lock.notify_all(thread);
1950 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1951 thread->clear_pending_exception();
1952 }
1953
1954 static bool is_daemon(oop threadObj) {
1955 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1956 }
1957
1958 // For any new cleanup additions, please check to see if they need to be applied to
1959 // cleanup_failed_attach_current_thread as well.
1960 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1961 assert(this == JavaThread::current(), "thread consistency check");
1962
1963 elapsedTimer _timer_exit_phase1;
1964 elapsedTimer _timer_exit_phase2;
1965 elapsedTimer _timer_exit_phase3;
1966 elapsedTimer _timer_exit_phase4;
1967
1968 if (log_is_enabled(Debug, os, thread, timer)) {
1969 _timer_exit_phase1.start();
1970 }
1971
1972 HandleMark hm(this);
1973 Handle uncaught_exception(this, this->pending_exception());
1974 this->clear_pending_exception();
1975 Handle threadObj(this, this->threadObj());
1976 assert(threadObj.not_null(), "Java thread object should be created");
1977
1978 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1979 {
1980 EXCEPTION_MARK;
1981
1982 CLEAR_PENDING_EXCEPTION;
1983 }
1984 if (!destroy_vm) {
1985 if (uncaught_exception.not_null()) {
1986 EXCEPTION_MARK;
1987 // Call method Thread.dispatchUncaughtException().
1988 Klass* thread_klass = SystemDictionary::Thread_klass();
1989 JavaValue result(T_VOID);
1990 JavaCalls::call_virtual(&result,
1991 threadObj, thread_klass,
1992 vmSymbols::dispatchUncaughtException_name(),
1993 vmSymbols::throwable_void_signature(),
1994 uncaught_exception,
1995 THREAD);
1996 if (HAS_PENDING_EXCEPTION) {
1997 ResourceMark rm(this);
1998 jio_fprintf(defaultStream::error_stream(),
1999 "\nException: %s thrown from the UncaughtExceptionHandler"
2000 " in thread \"%s\"\n",
2001 pending_exception()->klass()->external_name(),
2002 get_thread_name());
2003 CLEAR_PENDING_EXCEPTION;
2004 }
2005 }
2006 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2007
2008 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2009 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2010 // is deprecated anyhow.
2011 if (!is_Compiler_thread()) {
2012 int count = 3;
2013 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2014 EXCEPTION_MARK;
2015 JavaValue result(T_VOID);
2016 Klass* thread_klass = SystemDictionary::Thread_klass();
2017 JavaCalls::call_virtual(&result,
2018 threadObj, thread_klass,
2019 vmSymbols::exit_method_name(),
2020 vmSymbols::void_method_signature(),
2021 THREAD);
2022 CLEAR_PENDING_EXCEPTION;
2023 }
2024 }
2025 // notify JVMTI
2026 if (JvmtiExport::should_post_thread_life()) {
2027 JvmtiExport::post_thread_end(this);
2028 }
2029
2030 // We have notified the agents that we are exiting, before we go on,
2031 // we must check for a pending external suspend request and honor it
2032 // in order to not surprise the thread that made the suspend request.
2033 while (true) {
2034 {
2035 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2036 if (!is_external_suspend()) {
2037 set_terminated(_thread_exiting);
2038 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2039 break;
2040 }
2041 // Implied else:
2042 // Things get a little tricky here. We have a pending external
2043 // suspend request, but we are holding the SR_lock so we
2044 // can't just self-suspend. So we temporarily drop the lock
2045 // and then self-suspend.
2046 }
2047
2048 ThreadBlockInVM tbivm(this);
2049 java_suspend_self();
2050
2051 // We're done with this suspend request, but we have to loop around
2052 // and check again. Eventually we will get SR_lock without a pending
2053 // external suspend request and will be able to mark ourselves as
2054 // exiting.
2055 }
2056 // no more external suspends are allowed at this point
2057 } else {
2058 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2059 // before_exit() has already posted JVMTI THREAD_END events
2060 }
2061
2062 if (log_is_enabled(Debug, os, thread, timer)) {
2063 _timer_exit_phase1.stop();
2064 _timer_exit_phase2.start();
2065 }
2066
2067 // Capture daemon status before the thread is marked as terminated.
2068 bool daemon = is_daemon(threadObj());
2069
2070 // Notify waiters on thread object. This has to be done after exit() is called
2071 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2072 // group should have the destroyed bit set before waiters are notified).
2073 ensure_join(this);
2074 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2075
2076 if (log_is_enabled(Debug, os, thread, timer)) {
2077 _timer_exit_phase2.stop();
2078 _timer_exit_phase3.start();
2079 }
2080 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2081 // held by this thread must be released. The spec does not distinguish
2082 // between JNI-acquired and regular Java monitors. We can only see
2083 // regular Java monitors here if monitor enter-exit matching is broken.
2084 //
2085 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2086 // ObjectSynchronizer::release_monitors_owned_by_thread().
2087 if (exit_type == jni_detach) {
2088 // Sanity check even though JNI DetachCurrentThread() would have
2089 // returned JNI_ERR if there was a Java frame. JavaThread exit
2090 // should be done executing Java code by the time we get here.
2091 assert(!this->has_last_Java_frame(),
2092 "should not have a Java frame when detaching or exiting");
2093 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2094 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2095 }
2096
2097 // These things needs to be done while we are still a Java Thread. Make sure that thread
2098 // is in a consistent state, in case GC happens
2099 JFR_ONLY(Jfr::on_thread_exit(this);)
2100
2101 if (active_handles() != NULL) {
2102 JNIHandleBlock* block = active_handles();
2103 set_active_handles(NULL);
2104 JNIHandleBlock::release_block(block);
2105 }
2106
2107 if (free_handle_block() != NULL) {
2108 JNIHandleBlock* block = free_handle_block();
2109 set_free_handle_block(NULL);
2110 JNIHandleBlock::release_block(block);
2111 }
2112
2113 // These have to be removed while this is still a valid thread.
2114 remove_stack_guard_pages();
2115
2116 if (UseTLAB) {
2117 tlab().retire();
2118 }
2119
2120 if (JvmtiEnv::environments_might_exist()) {
2121 JvmtiExport::cleanup_thread(this);
2122 }
2123
2124 // We must flush any deferred card marks and other various GC barrier
2125 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2126 // before removing a thread from the list of active threads.
2127 BarrierSet::barrier_set()->on_thread_detach(this);
2128
2129 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2130 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2131 os::current_thread_id());
2132
2133 if (log_is_enabled(Debug, os, thread, timer)) {
2134 _timer_exit_phase3.stop();
2135 _timer_exit_phase4.start();
2136 }
2137 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2138 Threads::remove(this, daemon);
2139
2140 if (log_is_enabled(Debug, os, thread, timer)) {
2141 _timer_exit_phase4.stop();
2142 ResourceMark rm(this);
2143 log_debug(os, thread, timer)("name='%s'"
2144 ", exit-phase1=" JLONG_FORMAT
2145 ", exit-phase2=" JLONG_FORMAT
2146 ", exit-phase3=" JLONG_FORMAT
2147 ", exit-phase4=" JLONG_FORMAT,
2148 get_thread_name(),
2149 _timer_exit_phase1.milliseconds(),
2150 _timer_exit_phase2.milliseconds(),
2151 _timer_exit_phase3.milliseconds(),
2152 _timer_exit_phase4.milliseconds());
2153 }
2154 }
2155
2156 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2157 if (active_handles() != NULL) {
2158 JNIHandleBlock* block = active_handles();
2159 set_active_handles(NULL);
2160 JNIHandleBlock::release_block(block);
2161 }
2162
2163 if (free_handle_block() != NULL) {
2164 JNIHandleBlock* block = free_handle_block();
2165 set_free_handle_block(NULL);
2166 JNIHandleBlock::release_block(block);
2167 }
2168
2169 // These have to be removed while this is still a valid thread.
2170 remove_stack_guard_pages();
2171
2172 if (UseTLAB) {
2173 tlab().retire();
2174 }
2175
2176 BarrierSet::barrier_set()->on_thread_detach(this);
2177
2178 Threads::remove(this, is_daemon);
2179 this->smr_delete();
2180 }
2181
2182 JavaThread* JavaThread::active() {
2183 Thread* thread = Thread::current();
2184 if (thread->is_Java_thread()) {
2185 return (JavaThread*) thread;
2186 } else {
2187 assert(thread->is_VM_thread(), "this must be a vm thread");
2188 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2189 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2190 assert(ret->is_Java_thread(), "must be a Java thread");
2191 return ret;
2192 }
2193 }
2194
2195 bool JavaThread::is_lock_owned(address adr) const {
2196 if (Thread::is_lock_owned(adr)) return true;
2197
2198 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2199 if (chunk->contains(adr)) return true;
2200 }
2201
2202 return false;
2203 }
2204
2205
2206 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2207 chunk->set_next(monitor_chunks());
2208 set_monitor_chunks(chunk);
2209 }
2210
2211 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2212 guarantee(monitor_chunks() != NULL, "must be non empty");
2213 if (monitor_chunks() == chunk) {
2214 set_monitor_chunks(chunk->next());
2215 } else {
2216 MonitorChunk* prev = monitor_chunks();
2217 while (prev->next() != chunk) prev = prev->next();
2218 prev->set_next(chunk->next());
2219 }
2220 }
2221
2222 // JVM support.
2223
2224 // Note: this function shouldn't block if it's called in
2225 // _thread_in_native_trans state (such as from
2226 // check_special_condition_for_native_trans()).
2227 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2228
2229 if (has_last_Java_frame() && has_async_condition()) {
2230 // If we are at a polling page safepoint (not a poll return)
2231 // then we must defer async exception because live registers
2232 // will be clobbered by the exception path. Poll return is
2233 // ok because the call we a returning from already collides
2234 // with exception handling registers and so there is no issue.
2235 // (The exception handling path kills call result registers but
2236 // this is ok since the exception kills the result anyway).
2237
2238 if (is_at_poll_safepoint()) {
2239 // if the code we are returning to has deoptimized we must defer
2240 // the exception otherwise live registers get clobbered on the
2241 // exception path before deoptimization is able to retrieve them.
2242 //
2243 RegisterMap map(this, false);
2244 frame caller_fr = last_frame().sender(&map);
2245 assert(caller_fr.is_compiled_frame(), "what?");
2246 if (caller_fr.is_deoptimized_frame()) {
2247 log_info(exceptions)("deferred async exception at compiled safepoint");
2248 return;
2249 }
2250 }
2251 }
2252
2253 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2254 if (condition == _no_async_condition) {
2255 // Conditions have changed since has_special_runtime_exit_condition()
2256 // was called:
2257 // - if we were here only because of an external suspend request,
2258 // then that was taken care of above (or cancelled) so we are done
2259 // - if we were here because of another async request, then it has
2260 // been cleared between the has_special_runtime_exit_condition()
2261 // and now so again we are done
2262 return;
2263 }
2264
2265 // Check for pending async. exception
2266 if (_pending_async_exception != NULL) {
2267 // Only overwrite an already pending exception, if it is not a threadDeath.
2268 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2269
2270 // We cannot call Exceptions::_throw(...) here because we cannot block
2271 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2272
2273 LogTarget(Info, exceptions) lt;
2274 if (lt.is_enabled()) {
2275 ResourceMark rm;
2276 LogStream ls(lt);
2277 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2278 if (has_last_Java_frame()) {
2279 frame f = last_frame();
2280 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2281 }
2282 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2283 }
2284 _pending_async_exception = NULL;
2285 clear_has_async_exception();
2286 }
2287 }
2288
2289 if (check_unsafe_error &&
2290 condition == _async_unsafe_access_error && !has_pending_exception()) {
2291 condition = _no_async_condition; // done
2292 switch (thread_state()) {
2293 case _thread_in_vm: {
2294 JavaThread* THREAD = this;
2295 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2296 }
2297 case _thread_in_native: {
2298 ThreadInVMfromNative tiv(this);
2299 JavaThread* THREAD = this;
2300 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2301 }
2302 case _thread_in_Java: {
2303 ThreadInVMfromJava tiv(this);
2304 JavaThread* THREAD = this;
2305 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2306 }
2307 default:
2308 ShouldNotReachHere();
2309 }
2310 }
2311
2312 assert(condition == _no_async_condition || has_pending_exception() ||
2313 (!check_unsafe_error && condition == _async_unsafe_access_error),
2314 "must have handled the async condition, if no exception");
2315 }
2316
2317 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2318
2319 // Check for pending external suspend.
2320 if (is_external_suspend_with_lock()) {
2321 frame_anchor()->make_walkable(this);
2322 java_suspend_self_with_safepoint_check();
2323 }
2324
2325 // We might be here for reasons in addition to the self-suspend request
2326 // so check for other async requests.
2327 if (check_asyncs) {
2328 check_and_handle_async_exceptions();
2329 }
2330
2331 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2332 }
2333
2334 void JavaThread::send_thread_stop(oop java_throwable) {
2335 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2336 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2337 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2338
2339 // Do not throw asynchronous exceptions against the compiler thread
2340 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2341 if (!can_call_java()) return;
2342
2343 {
2344 // Actually throw the Throwable against the target Thread - however
2345 // only if there is no thread death exception installed already.
2346 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2347 // If the topmost frame is a runtime stub, then we are calling into
2348 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2349 // must deoptimize the caller before continuing, as the compiled exception handler table
2350 // may not be valid
2351 if (has_last_Java_frame()) {
2352 frame f = last_frame();
2353 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2354 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2355 RegisterMap reg_map(this, UseBiasedLocking);
2356 frame compiled_frame = f.sender(®_map);
2357 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2358 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2359 }
2360 }
2361 }
2362
2363 // Set async. pending exception in thread.
2364 set_pending_async_exception(java_throwable);
2365
2366 if (log_is_enabled(Info, exceptions)) {
2367 ResourceMark rm;
2368 log_info(exceptions)("Pending Async. exception installed of type: %s",
2369 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2370 }
2371 // for AbortVMOnException flag
2372 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2373 }
2374 }
2375
2376
2377 // Interrupt thread so it will wake up from a potential wait()
2378 Thread::interrupt(this);
2379 }
2380
2381 // External suspension mechanism.
2382 //
2383 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2384 // to any VM_locks and it is at a transition
2385 // Self-suspension will happen on the transition out of the vm.
2386 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2387 //
2388 // Guarantees on return:
2389 // + Target thread will not execute any new bytecode (that's why we need to
2390 // force a safepoint)
2391 // + Target thread will not enter any new monitors
2392 //
2393 void JavaThread::java_suspend() {
2394 ThreadsListHandle tlh;
2395 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2396 return;
2397 }
2398
2399 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2400 if (!is_external_suspend()) {
2401 // a racing resume has cancelled us; bail out now
2402 return;
2403 }
2404
2405 // suspend is done
2406 uint32_t debug_bits = 0;
2407 // Warning: is_ext_suspend_completed() may temporarily drop the
2408 // SR_lock to allow the thread to reach a stable thread state if
2409 // it is currently in a transient thread state.
2410 if (is_ext_suspend_completed(false /* !called_by_wait */,
2411 SuspendRetryDelay, &debug_bits)) {
2412 return;
2413 }
2414 }
2415
2416 if (Thread::current() == this) {
2417 // Safely self-suspend.
2418 // If we don't do this explicitly it will implicitly happen
2419 // before we transition back to Java, and on some other thread-state
2420 // transition paths, but not as we exit a JVM TI SuspendThread call.
2421 // As SuspendThread(current) must not return (until resumed) we must
2422 // self-suspend here.
2423 ThreadBlockInVM tbivm(this);
2424 java_suspend_self();
2425 } else {
2426 VM_ThreadSuspend vm_suspend;
2427 VMThread::execute(&vm_suspend);
2428 }
2429 }
2430
2431 // Part II of external suspension.
2432 // A JavaThread self suspends when it detects a pending external suspend
2433 // request. This is usually on transitions. It is also done in places
2434 // where continuing to the next transition would surprise the caller,
2435 // e.g., monitor entry.
2436 //
2437 // Returns the number of times that the thread self-suspended.
2438 //
2439 // Note: DO NOT call java_suspend_self() when you just want to block current
2440 // thread. java_suspend_self() is the second stage of cooperative
2441 // suspension for external suspend requests and should only be used
2442 // to complete an external suspend request.
2443 //
2444 int JavaThread::java_suspend_self() {
2445 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2446 int ret = 0;
2447
2448 // we are in the process of exiting so don't suspend
2449 if (is_exiting()) {
2450 clear_external_suspend();
2451 return ret;
2452 }
2453
2454 assert(_anchor.walkable() ||
2455 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2456 "must have walkable stack");
2457
2458 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2459
2460 assert(!this->is_ext_suspended(),
2461 "a thread trying to self-suspend should not already be suspended");
2462
2463 if (this->is_suspend_equivalent()) {
2464 // If we are self-suspending as a result of the lifting of a
2465 // suspend equivalent condition, then the suspend_equivalent
2466 // flag is not cleared until we set the ext_suspended flag so
2467 // that wait_for_ext_suspend_completion() returns consistent
2468 // results.
2469 this->clear_suspend_equivalent();
2470 }
2471
2472 // A racing resume may have cancelled us before we grabbed SR_lock
2473 // above. Or another external suspend request could be waiting for us
2474 // by the time we return from SR_lock()->wait(). The thread
2475 // that requested the suspension may already be trying to walk our
2476 // stack and if we return now, we can change the stack out from under
2477 // it. This would be a "bad thing (TM)" and cause the stack walker
2478 // to crash. We stay self-suspended until there are no more pending
2479 // external suspend requests.
2480 while (is_external_suspend()) {
2481 ret++;
2482 this->set_ext_suspended();
2483
2484 // _ext_suspended flag is cleared by java_resume()
2485 while (is_ext_suspended()) {
2486 ml.wait();
2487 }
2488 }
2489 return ret;
2490 }
2491
2492 // Helper routine to set up the correct thread state before calling java_suspend_self.
2493 // This is called when regular thread-state transition helpers can't be used because
2494 // we can be in various states, in particular _thread_in_native_trans.
2495 // Because this thread is external suspended the safepoint code will count it as at
2496 // a safepoint, regardless of what its actual current thread-state is. But
2497 // is_ext_suspend_completed() may be waiting to see a thread transition from
2498 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2499 // to _thread_blocked. The problem with setting thread state directly is that a
2500 // safepoint could happen just after java_suspend_self() returns after being resumed,
2501 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2502 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2503 // However, not all initial-states are allowed when performing a safepoint check, as we
2504 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2505 // only _thread_in_native is possible when executing this code (based on our two callers).
2506 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2507 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2508 // and so we don't need the explicit safepoint check.
2509
2510 void JavaThread::java_suspend_self_with_safepoint_check() {
2511 assert(this == Thread::current(), "invariant");
2512 JavaThreadState state = thread_state();
2513 set_thread_state(_thread_blocked);
2514 java_suspend_self();
2515 set_thread_state_fence(state);
2516 // Since we are not using a regular thread-state transition helper here,
2517 // we must manually emit the instruction barrier after leaving a safe state.
2518 OrderAccess::cross_modify_fence();
2519 if (state != _thread_in_native) {
2520 SafepointMechanism::block_if_requested(this);
2521 }
2522 }
2523
2524 #ifdef ASSERT
2525 // Verify the JavaThread has not yet been published in the Threads::list, and
2526 // hence doesn't need protection from concurrent access at this stage.
2527 void JavaThread::verify_not_published() {
2528 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2529 // since an unpublished JavaThread doesn't participate in the
2530 // Thread-SMR protocol for keeping a ThreadsList alive.
2531 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2532 }
2533 #endif
2534
2535 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2536 // progress or when _suspend_flags is non-zero.
2537 // Current thread needs to self-suspend if there is a suspend request and/or
2538 // block if a safepoint is in progress.
2539 // Async exception ISN'T checked.
2540 // Note only the ThreadInVMfromNative transition can call this function
2541 // directly and when thread state is _thread_in_native_trans
2542 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2543 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2544
2545 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2546
2547 if (thread->is_external_suspend()) {
2548 thread->java_suspend_self_with_safepoint_check();
2549 } else {
2550 SafepointMechanism::block_if_requested(thread);
2551 }
2552
2553 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2554 }
2555
2556 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2557 // progress or when _suspend_flags is non-zero.
2558 // Current thread needs to self-suspend if there is a suspend request and/or
2559 // block if a safepoint is in progress.
2560 // Also check for pending async exception (not including unsafe access error).
2561 // Note only the native==>VM/Java barriers can call this function and when
2562 // thread state is _thread_in_native_trans.
2563 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2564 check_safepoint_and_suspend_for_native_trans(thread);
2565
2566 if (thread->has_async_exception()) {
2567 // We are in _thread_in_native_trans state, don't handle unsafe
2568 // access error since that may block.
2569 thread->check_and_handle_async_exceptions(false);
2570 }
2571 }
2572
2573 // This is a variant of the normal
2574 // check_special_condition_for_native_trans with slightly different
2575 // semantics for use by critical native wrappers. It does all the
2576 // normal checks but also performs the transition back into
2577 // thread_in_Java state. This is required so that critical natives
2578 // can potentially block and perform a GC if they are the last thread
2579 // exiting the GCLocker.
2580 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2581 check_special_condition_for_native_trans(thread);
2582
2583 // Finish the transition
2584 thread->set_thread_state(_thread_in_Java);
2585
2586 if (thread->do_critical_native_unlock()) {
2587 ThreadInVMfromJavaNoAsyncException tiv(thread);
2588 GCLocker::unlock_critical(thread);
2589 thread->clear_critical_native_unlock();
2590 }
2591 }
2592
2593 // We need to guarantee the Threads_lock here, since resumes are not
2594 // allowed during safepoint synchronization
2595 // Can only resume from an external suspension
2596 void JavaThread::java_resume() {
2597 assert_locked_or_safepoint(Threads_lock);
2598
2599 // Sanity check: thread is gone, has started exiting or the thread
2600 // was not externally suspended.
2601 ThreadsListHandle tlh;
2602 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2603 return;
2604 }
2605
2606 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2607
2608 clear_external_suspend();
2609
2610 if (is_ext_suspended()) {
2611 clear_ext_suspended();
2612 SR_lock()->notify_all();
2613 }
2614 }
2615
2616 size_t JavaThread::_stack_red_zone_size = 0;
2617 size_t JavaThread::_stack_yellow_zone_size = 0;
2618 size_t JavaThread::_stack_reserved_zone_size = 0;
2619 size_t JavaThread::_stack_shadow_zone_size = 0;
2620
2621 void JavaThread::create_stack_guard_pages() {
2622 if (!os::uses_stack_guard_pages() ||
2623 _stack_guard_state != stack_guard_unused ||
2624 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2625 log_info(os, thread)("Stack guard page creation for thread "
2626 UINTX_FORMAT " disabled", os::current_thread_id());
2627 return;
2628 }
2629 address low_addr = stack_end();
2630 size_t len = stack_guard_zone_size();
2631
2632 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2633 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2634
2635 int must_commit = os::must_commit_stack_guard_pages();
2636 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2637
2638 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2639 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2640 return;
2641 }
2642
2643 if (os::guard_memory((char *) low_addr, len)) {
2644 _stack_guard_state = stack_guard_enabled;
2645 } else {
2646 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2647 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2648 if (os::uncommit_memory((char *) low_addr, len)) {
2649 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2650 }
2651 return;
2652 }
2653
2654 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2655 PTR_FORMAT "-" PTR_FORMAT ".",
2656 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2657 }
2658
2659 void JavaThread::remove_stack_guard_pages() {
2660 assert(Thread::current() == this, "from different thread");
2661 if (_stack_guard_state == stack_guard_unused) return;
2662 address low_addr = stack_end();
2663 size_t len = stack_guard_zone_size();
2664
2665 if (os::must_commit_stack_guard_pages()) {
2666 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2667 _stack_guard_state = stack_guard_unused;
2668 } else {
2669 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2670 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2671 return;
2672 }
2673 } else {
2674 if (_stack_guard_state == stack_guard_unused) return;
2675 if (os::unguard_memory((char *) low_addr, len)) {
2676 _stack_guard_state = stack_guard_unused;
2677 } else {
2678 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2679 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2680 return;
2681 }
2682 }
2683
2684 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2685 PTR_FORMAT "-" PTR_FORMAT ".",
2686 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2687 }
2688
2689 void JavaThread::enable_stack_reserved_zone() {
2690 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2691
2692 // The base notation is from the stack's point of view, growing downward.
2693 // We need to adjust it to work correctly with guard_memory()
2694 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2695
2696 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2697 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2698
2699 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2700 _stack_guard_state = stack_guard_enabled;
2701 } else {
2702 warning("Attempt to guard stack reserved zone failed.");
2703 }
2704 enable_register_stack_guard();
2705 }
2706
2707 void JavaThread::disable_stack_reserved_zone() {
2708 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2709
2710 // Simply return if called for a thread that does not use guard pages.
2711 if (_stack_guard_state != stack_guard_enabled) return;
2712
2713 // The base notation is from the stack's point of view, growing downward.
2714 // We need to adjust it to work correctly with guard_memory()
2715 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2716
2717 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2718 _stack_guard_state = stack_guard_reserved_disabled;
2719 } else {
2720 warning("Attempt to unguard stack reserved zone failed.");
2721 }
2722 disable_register_stack_guard();
2723 }
2724
2725 void JavaThread::enable_stack_yellow_reserved_zone() {
2726 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2727 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2728
2729 // The base notation is from the stacks point of view, growing downward.
2730 // We need to adjust it to work correctly with guard_memory()
2731 address base = stack_red_zone_base();
2732
2733 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2734 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2735
2736 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2737 _stack_guard_state = stack_guard_enabled;
2738 } else {
2739 warning("Attempt to guard stack yellow zone failed.");
2740 }
2741 enable_register_stack_guard();
2742 }
2743
2744 void JavaThread::disable_stack_yellow_reserved_zone() {
2745 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2746 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2747
2748 // Simply return if called for a thread that does not use guard pages.
2749 if (_stack_guard_state == stack_guard_unused) return;
2750
2751 // The base notation is from the stacks point of view, growing downward.
2752 // We need to adjust it to work correctly with guard_memory()
2753 address base = stack_red_zone_base();
2754
2755 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2756 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2757 } else {
2758 warning("Attempt to unguard stack yellow zone failed.");
2759 }
2760 disable_register_stack_guard();
2761 }
2762
2763 void JavaThread::enable_stack_red_zone() {
2764 // The base notation is from the stacks point of view, growing downward.
2765 // We need to adjust it to work correctly with guard_memory()
2766 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2767 address base = stack_red_zone_base() - stack_red_zone_size();
2768
2769 guarantee(base < stack_base(), "Error calculating stack red zone");
2770 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2771
2772 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2773 warning("Attempt to guard stack red zone failed.");
2774 }
2775 }
2776
2777 void JavaThread::disable_stack_red_zone() {
2778 // The base notation is from the stacks point of view, growing downward.
2779 // We need to adjust it to work correctly with guard_memory()
2780 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2781 address base = stack_red_zone_base() - stack_red_zone_size();
2782 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2783 warning("Attempt to unguard stack red zone failed.");
2784 }
2785 }
2786
2787 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2788 // ignore is there is no stack
2789 if (!has_last_Java_frame()) return;
2790 // traverse the stack frames. Starts from top frame.
2791 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2792 frame* fr = fst.current();
2793 f(fr, fst.register_map());
2794 }
2795 }
2796
2797
2798 #ifndef PRODUCT
2799 // Deoptimization
2800 // Function for testing deoptimization
2801 void JavaThread::deoptimize() {
2802 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2803 StackFrameStream fst(this, UseBiasedLocking);
2804 bool deopt = false; // Dump stack only if a deopt actually happens.
2805 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2806 // Iterate over all frames in the thread and deoptimize
2807 for (; !fst.is_done(); fst.next()) {
2808 if (fst.current()->can_be_deoptimized()) {
2809
2810 if (only_at) {
2811 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2812 // consists of comma or carriage return separated numbers so
2813 // search for the current bci in that string.
2814 address pc = fst.current()->pc();
2815 nmethod* nm = (nmethod*) fst.current()->cb();
2816 ScopeDesc* sd = nm->scope_desc_at(pc);
2817 char buffer[8];
2818 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2819 size_t len = strlen(buffer);
2820 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2821 while (found != NULL) {
2822 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2823 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2824 // Check that the bci found is bracketed by terminators.
2825 break;
2826 }
2827 found = strstr(found + 1, buffer);
2828 }
2829 if (!found) {
2830 continue;
2831 }
2832 }
2833
2834 if (DebugDeoptimization && !deopt) {
2835 deopt = true; // One-time only print before deopt
2836 tty->print_cr("[BEFORE Deoptimization]");
2837 trace_frames();
2838 trace_stack();
2839 }
2840 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2841 }
2842 }
2843
2844 if (DebugDeoptimization && deopt) {
2845 tty->print_cr("[AFTER Deoptimization]");
2846 trace_frames();
2847 }
2848 }
2849
2850
2851 // Make zombies
2852 void JavaThread::make_zombies() {
2853 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2854 if (fst.current()->can_be_deoptimized()) {
2855 // it is a Java nmethod
2856 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2857 nm->make_not_entrant();
2858 }
2859 }
2860 }
2861 #endif // PRODUCT
2862
2863
2864 void JavaThread::deoptimized_wrt_marked_nmethods() {
2865 if (!has_last_Java_frame()) return;
2866 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2867 StackFrameStream fst(this, UseBiasedLocking);
2868 for (; !fst.is_done(); fst.next()) {
2869 if (fst.current()->should_be_deoptimized()) {
2870 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2871 }
2872 }
2873 }
2874
2875
2876 // If the caller is a NamedThread, then remember, in the current scope,
2877 // the given JavaThread in its _processed_thread field.
2878 class RememberProcessedThread: public StackObj {
2879 NamedThread* _cur_thr;
2880 public:
2881 RememberProcessedThread(JavaThread* jthr) {
2882 Thread* thread = Thread::current();
2883 if (thread->is_Named_thread()) {
2884 _cur_thr = (NamedThread *)thread;
2885 _cur_thr->set_processed_thread(jthr);
2886 } else {
2887 _cur_thr = NULL;
2888 }
2889 }
2890
2891 ~RememberProcessedThread() {
2892 if (_cur_thr) {
2893 _cur_thr->set_processed_thread(NULL);
2894 }
2895 }
2896 };
2897
2898 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2899 // Verify that the deferred card marks have been flushed.
2900 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2901
2902 // Traverse the GCHandles
2903 Thread::oops_do(f, cf);
2904
2905 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2906 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2907
2908 if (has_last_Java_frame()) {
2909 // Record JavaThread to GC thread
2910 RememberProcessedThread rpt(this);
2911
2912 // traverse the registered growable array
2913 if (_array_for_gc != NULL) {
2914 for (int index = 0; index < _array_for_gc->length(); index++) {
2915 f->do_oop(_array_for_gc->adr_at(index));
2916 }
2917 }
2918
2919 // Traverse the monitor chunks
2920 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2921 chunk->oops_do(f);
2922 }
2923
2924 // Traverse the execution stack
2925 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2926 fst.current()->oops_do(f, cf, fst.register_map());
2927 }
2928 }
2929
2930 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2931 // If we have deferred set_locals there might be oops waiting to be
2932 // written
2933 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2934 if (list != NULL) {
2935 for (int i = 0; i < list->length(); i++) {
2936 list->at(i)->oops_do(f);
2937 }
2938 }
2939
2940 // Traverse instance variables at the end since the GC may be moving things
2941 // around using this function
2942 f->do_oop((oop*) &_threadObj);
2943 f->do_oop((oop*) &_vm_result);
2944 f->do_oop((oop*) &_exception_oop);
2945 f->do_oop((oop*) &_pending_async_exception);
2946
2947 if (jvmti_thread_state() != NULL) {
2948 jvmti_thread_state()->oops_do(f);
2949 }
2950 }
2951
2952 #ifdef ASSERT
2953 void JavaThread::verify_states_for_handshake() {
2954 // This checks that the thread has a correct frame state during a handshake.
2955 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2956 (has_last_Java_frame() && java_call_counter() > 0),
2957 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2958 has_last_Java_frame(), java_call_counter());
2959 }
2960 #endif
2961
2962 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2963 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2964 (has_last_Java_frame() && java_call_counter() > 0),
2965 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2966 has_last_Java_frame(), java_call_counter());
2967
2968 if (has_last_Java_frame()) {
2969 // Traverse the execution stack
2970 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2971 fst.current()->nmethods_do(cf);
2972 }
2973 }
2974 }
2975
2976 void JavaThread::metadata_do(MetadataClosure* f) {
2977 if (has_last_Java_frame()) {
2978 // Traverse the execution stack to call f() on the methods in the stack
2979 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2980 fst.current()->metadata_do(f);
2981 }
2982 } else if (is_Compiler_thread()) {
2983 // need to walk ciMetadata in current compile tasks to keep alive.
2984 CompilerThread* ct = (CompilerThread*)this;
2985 if (ct->env() != NULL) {
2986 ct->env()->metadata_do(f);
2987 }
2988 CompileTask* task = ct->task();
2989 if (task != NULL) {
2990 task->metadata_do(f);
2991 }
2992 }
2993 }
2994
2995 // Printing
2996 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2997 switch (_thread_state) {
2998 case _thread_uninitialized: return "_thread_uninitialized";
2999 case _thread_new: return "_thread_new";
3000 case _thread_new_trans: return "_thread_new_trans";
3001 case _thread_in_native: return "_thread_in_native";
3002 case _thread_in_native_trans: return "_thread_in_native_trans";
3003 case _thread_in_vm: return "_thread_in_vm";
3004 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3005 case _thread_in_Java: return "_thread_in_Java";
3006 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3007 case _thread_blocked: return "_thread_blocked";
3008 case _thread_blocked_trans: return "_thread_blocked_trans";
3009 default: return "unknown thread state";
3010 }
3011 }
3012
3013 #ifndef PRODUCT
3014 void JavaThread::print_thread_state_on(outputStream *st) const {
3015 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3016 };
3017 #endif // PRODUCT
3018
3019 // Called by Threads::print() for VM_PrintThreads operation
3020 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3021 st->print_raw("\"");
3022 st->print_raw(get_thread_name());
3023 st->print_raw("\" ");
3024 oop thread_oop = threadObj();
3025 if (thread_oop != NULL) {
3026 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3027 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3028 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3029 }
3030 Thread::print_on(st, print_extended_info);
3031 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3032 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3033 if (thread_oop != NULL) {
3034 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3035 }
3036 #ifndef PRODUCT
3037 _safepoint_state->print_on(st);
3038 #endif // PRODUCT
3039 if (is_Compiler_thread()) {
3040 CompileTask *task = ((CompilerThread*)this)->task();
3041 if (task != NULL) {
3042 st->print(" Compiling: ");
3043 task->print(st, NULL, true, false);
3044 } else {
3045 st->print(" No compile task");
3046 }
3047 st->cr();
3048 }
3049 }
3050
3051 void JavaThread::print() const { print_on(tty); }
3052
3053 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3054 st->print("%s", get_thread_name_string(buf, buflen));
3055 }
3056
3057 // Called by fatal error handler. The difference between this and
3058 // JavaThread::print() is that we can't grab lock or allocate memory.
3059 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3060 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3061 oop thread_obj = threadObj();
3062 if (thread_obj != NULL) {
3063 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3064 }
3065 st->print(" [");
3066 st->print("%s", _get_thread_state_name(_thread_state));
3067 if (osthread()) {
3068 st->print(", id=%d", osthread()->thread_id());
3069 }
3070 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3071 p2i(stack_end()), p2i(stack_base()));
3072 st->print("]");
3073
3074 ThreadsSMRSupport::print_info_on(this, st);
3075 return;
3076 }
3077
3078 // Verification
3079
3080 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3081
3082 void JavaThread::verify() {
3083 // Verify oops in the thread.
3084 oops_do(&VerifyOopClosure::verify_oop, NULL);
3085
3086 // Verify the stack frames.
3087 frames_do(frame_verify);
3088 }
3089
3090 // CR 6300358 (sub-CR 2137150)
3091 // Most callers of this method assume that it can't return NULL but a
3092 // thread may not have a name whilst it is in the process of attaching to
3093 // the VM - see CR 6412693, and there are places where a JavaThread can be
3094 // seen prior to having it's threadObj set (eg JNI attaching threads and
3095 // if vm exit occurs during initialization). These cases can all be accounted
3096 // for such that this method never returns NULL.
3097 const char* JavaThread::get_thread_name() const {
3098 #ifdef ASSERT
3099 // early safepoints can hit while current thread does not yet have TLS
3100 if (!SafepointSynchronize::is_at_safepoint()) {
3101 Thread *cur = Thread::current();
3102 if (!(cur->is_Java_thread() && cur == this)) {
3103 // Current JavaThreads are allowed to get their own name without
3104 // the Threads_lock.
3105 assert_locked_or_safepoint(Threads_lock);
3106 }
3107 }
3108 #endif // ASSERT
3109 return get_thread_name_string();
3110 }
3111
3112 // Returns a non-NULL representation of this thread's name, or a suitable
3113 // descriptive string if there is no set name
3114 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3115 const char* name_str;
3116 oop thread_obj = threadObj();
3117 if (thread_obj != NULL) {
3118 oop name = java_lang_Thread::name(thread_obj);
3119 if (name != NULL) {
3120 if (buf == NULL) {
3121 name_str = java_lang_String::as_utf8_string(name);
3122 } else {
3123 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3124 }
3125 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3126 name_str = "<no-name - thread is attaching>";
3127 } else {
3128 name_str = Thread::name();
3129 }
3130 } else {
3131 name_str = Thread::name();
3132 }
3133 assert(name_str != NULL, "unexpected NULL thread name");
3134 return name_str;
3135 }
3136
3137 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3138
3139 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3140 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3141 // Link Java Thread object <-> C++ Thread
3142
3143 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3144 // and put it into a new Handle. The Handle "thread_oop" can then
3145 // be used to pass the C++ thread object to other methods.
3146
3147 // Set the Java level thread object (jthread) field of the
3148 // new thread (a JavaThread *) to C++ thread object using the
3149 // "thread_oop" handle.
3150
3151 // Set the thread field (a JavaThread *) of the
3152 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3153
3154 Handle thread_oop(Thread::current(),
3155 JNIHandles::resolve_non_null(jni_thread));
3156 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3157 "must be initialized");
3158 set_threadObj(thread_oop());
3159 java_lang_Thread::set_thread(thread_oop(), this);
3160
3161 if (prio == NoPriority) {
3162 prio = java_lang_Thread::priority(thread_oop());
3163 assert(prio != NoPriority, "A valid priority should be present");
3164 }
3165
3166 // Push the Java priority down to the native thread; needs Threads_lock
3167 Thread::set_priority(this, prio);
3168
3169 // Add the new thread to the Threads list and set it in motion.
3170 // We must have threads lock in order to call Threads::add.
3171 // It is crucial that we do not block before the thread is
3172 // added to the Threads list for if a GC happens, then the java_thread oop
3173 // will not be visited by GC.
3174 Threads::add(this);
3175 }
3176
3177 oop JavaThread::current_park_blocker() {
3178 // Support for JSR-166 locks
3179 oop thread_oop = threadObj();
3180 if (thread_oop != NULL) {
3181 return java_lang_Thread::park_blocker(thread_oop);
3182 }
3183 return NULL;
3184 }
3185
3186
3187 void JavaThread::print_stack_on(outputStream* st) {
3188 if (!has_last_Java_frame()) return;
3189 ResourceMark rm;
3190 HandleMark hm;
3191
3192 RegisterMap reg_map(this);
3193 vframe* start_vf = last_java_vframe(®_map);
3194 int count = 0;
3195 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3196 if (f->is_java_frame()) {
3197 javaVFrame* jvf = javaVFrame::cast(f);
3198 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3199
3200 // Print out lock information
3201 if (JavaMonitorsInStackTrace) {
3202 jvf->print_lock_info_on(st, count);
3203 }
3204 } else {
3205 // Ignore non-Java frames
3206 }
3207
3208 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3209 count++;
3210 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3211 }
3212 }
3213
3214
3215 // JVMTI PopFrame support
3216 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3217 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3218 if (in_bytes(size_in_bytes) != 0) {
3219 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3220 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3221 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3222 }
3223 }
3224
3225 void* JavaThread::popframe_preserved_args() {
3226 return _popframe_preserved_args;
3227 }
3228
3229 ByteSize JavaThread::popframe_preserved_args_size() {
3230 return in_ByteSize(_popframe_preserved_args_size);
3231 }
3232
3233 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3234 int sz = in_bytes(popframe_preserved_args_size());
3235 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3236 return in_WordSize(sz / wordSize);
3237 }
3238
3239 void JavaThread::popframe_free_preserved_args() {
3240 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3241 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3242 _popframe_preserved_args = NULL;
3243 _popframe_preserved_args_size = 0;
3244 }
3245
3246 #ifndef PRODUCT
3247
3248 void JavaThread::trace_frames() {
3249 tty->print_cr("[Describe stack]");
3250 int frame_no = 1;
3251 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3252 tty->print(" %d. ", frame_no++);
3253 fst.current()->print_value_on(tty, this);
3254 tty->cr();
3255 }
3256 }
3257
3258 class PrintAndVerifyOopClosure: public OopClosure {
3259 protected:
3260 template <class T> inline void do_oop_work(T* p) {
3261 oop obj = RawAccess<>::oop_load(p);
3262 if (obj == NULL) return;
3263 tty->print(INTPTR_FORMAT ": ", p2i(p));
3264 if (oopDesc::is_oop_or_null(obj)) {
3265 if (obj->is_objArray()) {
3266 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3267 } else {
3268 obj->print();
3269 }
3270 } else {
3271 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3272 }
3273 tty->cr();
3274 }
3275 public:
3276 virtual void do_oop(oop* p) { do_oop_work(p); }
3277 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3278 };
3279
3280 #ifdef ASSERT
3281 // Print or validate the layout of stack frames
3282 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3283 ResourceMark rm;
3284 PRESERVE_EXCEPTION_MARK;
3285 FrameValues values;
3286 int frame_no = 0;
3287 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3288 fst.current()->describe(values, ++frame_no);
3289 if (depth == frame_no) break;
3290 }
3291 if (validate_only) {
3292 values.validate();
3293 } else {
3294 tty->print_cr("[Describe stack layout]");
3295 values.print(this);
3296 }
3297 }
3298 #endif
3299
3300 void JavaThread::trace_stack_from(vframe* start_vf) {
3301 ResourceMark rm;
3302 int vframe_no = 1;
3303 for (vframe* f = start_vf; f; f = f->sender()) {
3304 if (f->is_java_frame()) {
3305 javaVFrame::cast(f)->print_activation(vframe_no++);
3306 } else {
3307 f->print();
3308 }
3309 if (vframe_no > StackPrintLimit) {
3310 tty->print_cr("...<more frames>...");
3311 return;
3312 }
3313 }
3314 }
3315
3316
3317 void JavaThread::trace_stack() {
3318 if (!has_last_Java_frame()) return;
3319 ResourceMark rm;
3320 HandleMark hm;
3321 RegisterMap reg_map(this);
3322 trace_stack_from(last_java_vframe(®_map));
3323 }
3324
3325
3326 #endif // PRODUCT
3327
3328
3329 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3330 assert(reg_map != NULL, "a map must be given");
3331 frame f = last_frame();
3332 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3333 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3334 }
3335 return NULL;
3336 }
3337
3338
3339 Klass* JavaThread::security_get_caller_class(int depth) {
3340 vframeStream vfst(this);
3341 vfst.security_get_caller_frame(depth);
3342 if (!vfst.at_end()) {
3343 return vfst.method()->method_holder();
3344 }
3345 return NULL;
3346 }
3347
3348 // java.lang.Thread.sleep support
3349 // Returns true if sleep time elapsed as expected, and false
3350 // if the thread was interrupted.
3351 bool JavaThread::sleep(jlong millis) {
3352 assert(this == Thread::current(), "thread consistency check");
3353
3354 ParkEvent * const slp = this->_SleepEvent;
3355 // Because there can be races with thread interruption sending an unpark()
3356 // to the event, we explicitly reset it here to avoid an immediate return.
3357 // The actual interrupt state will be checked before we park().
3358 slp->reset();
3359 // Thread interruption establishes a happens-before ordering in the
3360 // Java Memory Model, so we need to ensure we synchronize with the
3361 // interrupt state.
3362 OrderAccess::fence();
3363
3364 jlong prevtime = os::javaTimeNanos();
3365
3366 for (;;) {
3367 // interruption has precedence over timing out
3368 if (os::is_interrupted(this, true)) {
3369 return false;
3370 }
3371
3372 if (millis <= 0) {
3373 return true;
3374 }
3375
3376 {
3377 ThreadBlockInVM tbivm(this);
3378 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3379
3380 this->set_suspend_equivalent();
3381 // cleared by handle_special_suspend_equivalent_condition() or
3382 // java_suspend_self() via check_and_wait_while_suspended()
3383
3384 slp->park(millis);
3385
3386 // were we externally suspended while we were waiting?
3387 this->check_and_wait_while_suspended();
3388 }
3389
3390 // Update elapsed time tracking
3391 jlong newtime = os::javaTimeNanos();
3392 if (newtime - prevtime < 0) {
3393 // time moving backwards, should only happen if no monotonic clock
3394 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3395 assert(!os::supports_monotonic_clock(),
3396 "unexpected time moving backwards detected in os::sleep()");
3397 } else {
3398 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3399 }
3400 prevtime = newtime;
3401 }
3402 }
3403
3404
3405 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3406 assert(thread->is_Compiler_thread(), "must be compiler thread");
3407 CompileBroker::compiler_thread_loop();
3408 }
3409
3410 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3411 NMethodSweeper::sweeper_loop();
3412 }
3413
3414 // Create a CompilerThread
3415 CompilerThread::CompilerThread(CompileQueue* queue,
3416 CompilerCounters* counters)
3417 : JavaThread(&compiler_thread_entry) {
3418 _env = NULL;
3419 _log = NULL;
3420 _task = NULL;
3421 _queue = queue;
3422 _counters = counters;
3423 _buffer_blob = NULL;
3424 _compiler = NULL;
3425
3426 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3427 resource_area()->bias_to(mtCompiler);
3428
3429 #ifndef PRODUCT
3430 _ideal_graph_printer = NULL;
3431 #endif
3432 }
3433
3434 CompilerThread::~CompilerThread() {
3435 // Delete objects which were allocated on heap.
3436 delete _counters;
3437 }
3438
3439 bool CompilerThread::can_call_java() const {
3440 return _compiler != NULL && _compiler->is_jvmci();
3441 }
3442
3443 // Create sweeper thread
3444 CodeCacheSweeperThread::CodeCacheSweeperThread()
3445 : JavaThread(&sweeper_thread_entry) {
3446 _scanned_compiled_method = NULL;
3447 }
3448
3449 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3450 JavaThread::oops_do(f, cf);
3451 if (_scanned_compiled_method != NULL && cf != NULL) {
3452 // Safepoints can occur when the sweeper is scanning an nmethod so
3453 // process it here to make sure it isn't unloaded in the middle of
3454 // a scan.
3455 cf->do_code_blob(_scanned_compiled_method);
3456 }
3457 }
3458
3459 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3460 JavaThread::nmethods_do(cf);
3461 if (_scanned_compiled_method != NULL && cf != NULL) {
3462 // Safepoints can occur when the sweeper is scanning an nmethod so
3463 // process it here to make sure it isn't unloaded in the middle of
3464 // a scan.
3465 cf->do_code_blob(_scanned_compiled_method);
3466 }
3467 }
3468
3469
3470 // ======= Threads ========
3471
3472 // The Threads class links together all active threads, and provides
3473 // operations over all threads. It is protected by the Threads_lock,
3474 // which is also used in other global contexts like safepointing.
3475 // ThreadsListHandles are used to safely perform operations on one
3476 // or more threads without the risk of the thread exiting during the
3477 // operation.
3478 //
3479 // Note: The Threads_lock is currently more widely used than we
3480 // would like. We are actively migrating Threads_lock uses to other
3481 // mechanisms in order to reduce Threads_lock contention.
3482
3483 int Threads::_number_of_threads = 0;
3484 int Threads::_number_of_non_daemon_threads = 0;
3485 int Threads::_return_code = 0;
3486 uintx Threads::_thread_claim_token = 1; // Never zero.
3487 size_t JavaThread::_stack_size_at_create = 0;
3488
3489 #ifdef ASSERT
3490 bool Threads::_vm_complete = false;
3491 #endif
3492
3493 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3494 Prefetch::read((void*)addr, prefetch_interval);
3495 return *addr;
3496 }
3497
3498 // Possibly the ugliest for loop the world has seen. C++ does not allow
3499 // multiple types in the declaration section of the for loop. In this case
3500 // we are only dealing with pointers and hence can cast them. It looks ugly
3501 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3502 #define DO_JAVA_THREADS(LIST, X) \
3503 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3504 *MACRO_list = (JavaThread*)(LIST), \
3505 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3506 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3507 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3508 MACRO_current_p != MACRO_end; \
3509 MACRO_current_p++, \
3510 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3511
3512 // All JavaThreads
3513 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3514
3515 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3516 void Threads::non_java_threads_do(ThreadClosure* tc) {
3517 NoSafepointVerifier nsv;
3518 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3519 tc->do_thread(njti.current());
3520 }
3521 }
3522
3523 // All JavaThreads
3524 void Threads::java_threads_do(ThreadClosure* tc) {
3525 assert_locked_or_safepoint(Threads_lock);
3526 // ALL_JAVA_THREADS iterates through all JavaThreads.
3527 ALL_JAVA_THREADS(p) {
3528 tc->do_thread(p);
3529 }
3530 }
3531
3532 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3533 assert_locked_or_safepoint(Threads_lock);
3534 java_threads_do(tc);
3535 tc->do_thread(VMThread::vm_thread());
3536 }
3537
3538 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3539 void Threads::threads_do(ThreadClosure* tc) {
3540 assert_locked_or_safepoint(Threads_lock);
3541 java_threads_do(tc);
3542 non_java_threads_do(tc);
3543 }
3544
3545 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3546 uintx claim_token = Threads::thread_claim_token();
3547 ALL_JAVA_THREADS(p) {
3548 if (p->claim_threads_do(is_par, claim_token)) {
3549 tc->do_thread(p);
3550 }
3551 }
3552 VMThread* vmt = VMThread::vm_thread();
3553 if (vmt->claim_threads_do(is_par, claim_token)) {
3554 tc->do_thread(vmt);
3555 }
3556 }
3557
3558 // The system initialization in the library has three phases.
3559 //
3560 // Phase 1: java.lang.System class initialization
3561 // java.lang.System is a primordial class loaded and initialized
3562 // by the VM early during startup. java.lang.System.<clinit>
3563 // only does registerNatives and keeps the rest of the class
3564 // initialization work later until thread initialization completes.
3565 //
3566 // System.initPhase1 initializes the system properties, the static
3567 // fields in, out, and err. Set up java signal handlers, OS-specific
3568 // system settings, and thread group of the main thread.
3569 static void call_initPhase1(TRAPS) {
3570 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3571 JavaValue result(T_VOID);
3572 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3573 vmSymbols::void_method_signature(), CHECK);
3574 }
3575
3576 // Phase 2. Module system initialization
3577 // This will initialize the module system. Only java.base classes
3578 // can be loaded until phase 2 completes.
3579 //
3580 // Call System.initPhase2 after the compiler initialization and jsr292
3581 // classes get initialized because module initialization runs a lot of java
3582 // code, that for performance reasons, should be compiled. Also, this will
3583 // enable the startup code to use lambda and other language features in this
3584 // phase and onward.
3585 //
3586 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3587 static void call_initPhase2(TRAPS) {
3588 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3589
3590 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3591
3592 JavaValue result(T_INT);
3593 JavaCallArguments args;
3594 args.push_int(DisplayVMOutputToStderr);
3595 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3596 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3597 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3598 if (result.get_jint() != JNI_OK) {
3599 vm_exit_during_initialization(); // no message or exception
3600 }
3601
3602 universe_post_module_init();
3603 }
3604
3605 // Phase 3. final setup - set security manager, system class loader and TCCL
3606 //
3607 // This will instantiate and set the security manager, set the system class
3608 // loader as well as the thread context class loader. The security manager
3609 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3610 // other modules or the application's classpath.
3611 static void call_initPhase3(TRAPS) {
3612 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3613 JavaValue result(T_VOID);
3614 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3615 vmSymbols::void_method_signature(), CHECK);
3616 }
3617
3618 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3619 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3620
3621 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3622 create_vm_init_libraries();
3623 }
3624
3625 initialize_class(vmSymbols::java_lang_String(), CHECK);
3626
3627 // Inject CompactStrings value after the static initializers for String ran.
3628 java_lang_String::set_compact_strings(CompactStrings);
3629
3630 // Initialize java_lang.System (needed before creating the thread)
3631 initialize_class(vmSymbols::java_lang_System(), CHECK);
3632 // The VM creates & returns objects of this class. Make sure it's initialized.
3633 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3634 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3635 Handle thread_group = create_initial_thread_group(CHECK);
3636 Universe::set_main_thread_group(thread_group());
3637 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3638 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3639 main_thread->set_threadObj(thread_object);
3640
3641 // Set thread status to running since main thread has
3642 // been started and running.
3643 java_lang_Thread::set_thread_status(thread_object,
3644 java_lang_Thread::RUNNABLE);
3645
3646 // The VM creates objects of this class.
3647 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3648
3649 #ifdef ASSERT
3650 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3651 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3652 #endif
3653
3654 // initialize the hardware-specific constants needed by Unsafe
3655 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3656 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3657
3658 // The VM preresolves methods to these classes. Make sure that they get initialized
3659 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3660 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3661
3662 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3663 call_initPhase1(CHECK);
3664
3665 // get the Java runtime name after java.lang.System is initialized
3666 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3667 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3668
3669 // an instance of OutOfMemory exception has been allocated earlier
3670 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3671 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3672 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3673 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3674 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3675 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3676 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3677 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3678
3679 // Eager box cache initialization only if AOT is on and any library is loaded.
3680 AOTLoader::initialize_box_caches(CHECK);
3681 }
3682
3683 void Threads::initialize_jsr292_core_classes(TRAPS) {
3684 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3685
3686 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3687 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3688 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3689 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3690 }
3691
3692 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3693 extern void JDK_Version_init();
3694
3695 // Preinitialize version info.
3696 VM_Version::early_initialize();
3697
3698 // Check version
3699 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3700
3701 // Initialize library-based TLS
3702 ThreadLocalStorage::init();
3703
3704 // Initialize the output stream module
3705 ostream_init();
3706
3707 // Process java launcher properties.
3708 Arguments::process_sun_java_launcher_properties(args);
3709
3710 // Initialize the os module
3711 os::init();
3712
3713 // Record VM creation timing statistics
3714 TraceVmCreationTime create_vm_timer;
3715 create_vm_timer.start();
3716
3717 // Initialize system properties.
3718 Arguments::init_system_properties();
3719
3720 // So that JDK version can be used as a discriminator when parsing arguments
3721 JDK_Version_init();
3722
3723 // Update/Initialize System properties after JDK version number is known
3724 Arguments::init_version_specific_system_properties();
3725
3726 // Make sure to initialize log configuration *before* parsing arguments
3727 LogConfiguration::initialize(create_vm_timer.begin_time());
3728
3729 // Parse arguments
3730 // Note: this internally calls os::init_container_support()
3731 jint parse_result = Arguments::parse(args);
3732 if (parse_result != JNI_OK) return parse_result;
3733
3734 os::init_before_ergo();
3735
3736 jint ergo_result = Arguments::apply_ergo();
3737 if (ergo_result != JNI_OK) return ergo_result;
3738
3739 // Final check of all ranges after ergonomics which may change values.
3740 if (!JVMFlagRangeList::check_ranges()) {
3741 return JNI_EINVAL;
3742 }
3743
3744 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3745 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3746 if (!constraint_result) {
3747 return JNI_EINVAL;
3748 }
3749
3750 JVMFlagWriteableList::mark_startup();
3751
3752 if (PauseAtStartup) {
3753 os::pause();
3754 }
3755
3756 HOTSPOT_VM_INIT_BEGIN();
3757
3758 // Timing (must come after argument parsing)
3759 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3760
3761 // Initialize the os module after parsing the args
3762 jint os_init_2_result = os::init_2();
3763 if (os_init_2_result != JNI_OK) return os_init_2_result;
3764
3765 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3766 // Initialize assert poison page mechanism.
3767 if (ShowRegistersOnAssert) {
3768 initialize_assert_poison();
3769 }
3770 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3771
3772 SafepointMechanism::initialize();
3773
3774 jint adjust_after_os_result = Arguments::adjust_after_os();
3775 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3776
3777 // Initialize output stream logging
3778 ostream_init_log();
3779
3780 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3781 // Must be before create_vm_init_agents()
3782 if (Arguments::init_libraries_at_startup()) {
3783 convert_vm_init_libraries_to_agents();
3784 }
3785
3786 // Launch -agentlib/-agentpath and converted -Xrun agents
3787 if (Arguments::init_agents_at_startup()) {
3788 create_vm_init_agents();
3789 }
3790
3791 // Initialize Threads state
3792 _number_of_threads = 0;
3793 _number_of_non_daemon_threads = 0;
3794
3795 // Initialize global data structures and create system classes in heap
3796 vm_init_globals();
3797
3798 #if INCLUDE_JVMCI
3799 if (JVMCICounterSize > 0) {
3800 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3801 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3802 } else {
3803 JavaThread::_jvmci_old_thread_counters = NULL;
3804 }
3805 #endif // INCLUDE_JVMCI
3806
3807 // Attach the main thread to this os thread
3808 JavaThread* main_thread = new JavaThread();
3809 main_thread->set_thread_state(_thread_in_vm);
3810 main_thread->initialize_thread_current();
3811 // must do this before set_active_handles
3812 main_thread->record_stack_base_and_size();
3813 main_thread->register_thread_stack_with_NMT();
3814 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3815
3816 if (!main_thread->set_as_starting_thread()) {
3817 vm_shutdown_during_initialization(
3818 "Failed necessary internal allocation. Out of swap space");
3819 main_thread->smr_delete();
3820 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3821 return JNI_ENOMEM;
3822 }
3823
3824 // Enable guard page *after* os::create_main_thread(), otherwise it would
3825 // crash Linux VM, see notes in os_linux.cpp.
3826 main_thread->create_stack_guard_pages();
3827
3828 // Initialize Java-Level synchronization subsystem
3829 ObjectMonitor::Initialize();
3830
3831 // Initialize global modules
3832 jint status = init_globals();
3833 if (status != JNI_OK) {
3834 main_thread->smr_delete();
3835 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3836 return status;
3837 }
3838
3839 JFR_ONLY(Jfr::on_vm_init();)
3840
3841 // Should be done after the heap is fully created
3842 main_thread->cache_global_variables();
3843
3844 HandleMark hm;
3845
3846 { MutexLocker mu(Threads_lock);
3847 Threads::add(main_thread);
3848 }
3849
3850 // Any JVMTI raw monitors entered in onload will transition into
3851 // real raw monitor. VM is setup enough here for raw monitor enter.
3852 JvmtiExport::transition_pending_onload_raw_monitors();
3853
3854 // Create the VMThread
3855 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3856
3857 VMThread::create();
3858 Thread* vmthread = VMThread::vm_thread();
3859
3860 if (!os::create_thread(vmthread, os::vm_thread)) {
3861 vm_exit_during_initialization("Cannot create VM thread. "
3862 "Out of system resources.");
3863 }
3864
3865 // Wait for the VM thread to become ready, and VMThread::run to initialize
3866 // Monitors can have spurious returns, must always check another state flag
3867 {
3868 MonitorLocker ml(Notify_lock);
3869 os::start_thread(vmthread);
3870 while (vmthread->active_handles() == NULL) {
3871 ml.wait();
3872 }
3873 }
3874 }
3875
3876 assert(Universe::is_fully_initialized(), "not initialized");
3877 if (VerifyDuringStartup) {
3878 // Make sure we're starting with a clean slate.
3879 VM_Verify verify_op;
3880 VMThread::execute(&verify_op);
3881 }
3882
3883 // We need this to update the java.vm.info property in case any flags used
3884 // to initially define it have been changed. This is needed for both CDS and
3885 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3886 // is initially computed. See Abstract_VM_Version::vm_info_string().
3887 // This update must happen before we initialize the java classes, but
3888 // after any initialization logic that might modify the flags.
3889 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3890
3891 Thread* THREAD = Thread::current();
3892
3893 // Always call even when there are not JVMTI environments yet, since environments
3894 // may be attached late and JVMTI must track phases of VM execution
3895 JvmtiExport::enter_early_start_phase();
3896
3897 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3898 JvmtiExport::post_early_vm_start();
3899
3900 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3901
3902 quicken_jni_functions();
3903
3904 // No more stub generation allowed after that point.
3905 StubCodeDesc::freeze();
3906
3907 // Set flag that basic initialization has completed. Used by exceptions and various
3908 // debug stuff, that does not work until all basic classes have been initialized.
3909 set_init_completed();
3910
3911 LogConfiguration::post_initialize();
3912 Metaspace::post_initialize();
3913
3914 HOTSPOT_VM_INIT_END();
3915
3916 // record VM initialization completion time
3917 #if INCLUDE_MANAGEMENT
3918 Management::record_vm_init_completed();
3919 #endif // INCLUDE_MANAGEMENT
3920
3921 // Signal Dispatcher needs to be started before VMInit event is posted
3922 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3923
3924 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3925 if (!DisableAttachMechanism) {
3926 AttachListener::vm_start();
3927 if (StartAttachListener || AttachListener::init_at_startup()) {
3928 AttachListener::init();
3929 }
3930 }
3931
3932 // Launch -Xrun agents
3933 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3934 // back-end can launch with -Xdebug -Xrunjdwp.
3935 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3936 create_vm_init_libraries();
3937 }
3938
3939 if (CleanChunkPoolAsync) {
3940 Chunk::start_chunk_pool_cleaner_task();
3941 }
3942
3943
3944 // initialize compiler(s)
3945 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3946 #if INCLUDE_JVMCI
3947 bool force_JVMCI_intialization = false;
3948 if (EnableJVMCI) {
3949 // Initialize JVMCI eagerly when it is explicitly requested.
3950 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3951 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3952
3953 if (!force_JVMCI_intialization) {
3954 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3955 // compilations via JVMCI will not actually block until JVMCI is initialized.
3956 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3957 }
3958 }
3959 #endif
3960 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3961 // Postpone completion of compiler initialization to after JVMCI
3962 // is initialized to avoid timeouts of blocking compilations.
3963 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3964 CompileBroker::compilation_init_phase2();
3965 }
3966 #endif
3967
3968 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3969 // It is done after compilers are initialized, because otherwise compilations of
3970 // signature polymorphic MH intrinsics can be missed
3971 // (see SystemDictionary::find_method_handle_intrinsic).
3972 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3973
3974 // This will initialize the module system. Only java.base classes can be
3975 // loaded until phase 2 completes
3976 call_initPhase2(CHECK_JNI_ERR);
3977
3978 // Always call even when there are not JVMTI environments yet, since environments
3979 // may be attached late and JVMTI must track phases of VM execution
3980 JvmtiExport::enter_start_phase();
3981
3982 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3983 JvmtiExport::post_vm_start();
3984
3985 // Final system initialization including security manager and system class loader
3986 call_initPhase3(CHECK_JNI_ERR);
3987
3988 // cache the system and platform class loaders
3989 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3990
3991 #if INCLUDE_CDS
3992 // capture the module path info from the ModuleEntryTable
3993 ClassLoader::initialize_module_path(THREAD);
3994 #endif
3995
3996 #if INCLUDE_JVMCI
3997 if (force_JVMCI_intialization) {
3998 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3999 CompileBroker::compilation_init_phase2();
4000 }
4001 #endif
4002
4003 // Always call even when there are not JVMTI environments yet, since environments
4004 // may be attached late and JVMTI must track phases of VM execution
4005 JvmtiExport::enter_live_phase();
4006
4007 // Make perfmemory accessible
4008 PerfMemory::set_accessible(true);
4009
4010 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4011 JvmtiExport::post_vm_initialized();
4012
4013 JFR_ONLY(Jfr::on_vm_start();)
4014
4015 #if INCLUDE_MANAGEMENT
4016 Management::initialize(THREAD);
4017
4018 if (HAS_PENDING_EXCEPTION) {
4019 // management agent fails to start possibly due to
4020 // configuration problem and is responsible for printing
4021 // stack trace if appropriate. Simply exit VM.
4022 vm_exit(1);
4023 }
4024 #endif // INCLUDE_MANAGEMENT
4025
4026 if (MemProfiling) MemProfiler::engage();
4027 StatSampler::engage();
4028 if (CheckJNICalls) JniPeriodicChecker::engage();
4029
4030 BiasedLocking::init();
4031
4032 #if INCLUDE_RTM_OPT
4033 RTMLockingCounters::init();
4034 #endif
4035
4036 call_postVMInitHook(THREAD);
4037 // The Java side of PostVMInitHook.run must deal with all
4038 // exceptions and provide means of diagnosis.
4039 if (HAS_PENDING_EXCEPTION) {
4040 CLEAR_PENDING_EXCEPTION;
4041 }
4042
4043 {
4044 MutexLocker ml(PeriodicTask_lock);
4045 // Make sure the WatcherThread can be started by WatcherThread::start()
4046 // or by dynamic enrollment.
4047 WatcherThread::make_startable();
4048 // Start up the WatcherThread if there are any periodic tasks
4049 // NOTE: All PeriodicTasks should be registered by now. If they
4050 // aren't, late joiners might appear to start slowly (we might
4051 // take a while to process their first tick).
4052 if (PeriodicTask::num_tasks() > 0) {
4053 WatcherThread::start();
4054 }
4055 }
4056
4057 create_vm_timer.end();
4058 #ifdef ASSERT
4059 _vm_complete = true;
4060 #endif
4061
4062 if (DumpSharedSpaces) {
4063 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4064 ShouldNotReachHere();
4065 }
4066
4067 return JNI_OK;
4068 }
4069
4070 // type for the Agent_OnLoad and JVM_OnLoad entry points
4071 extern "C" {
4072 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4073 }
4074 // Find a command line agent library and return its entry point for
4075 // -agentlib: -agentpath: -Xrun
4076 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4077 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4078 const char *on_load_symbols[],
4079 size_t num_symbol_entries) {
4080 OnLoadEntry_t on_load_entry = NULL;
4081 void *library = NULL;
4082
4083 if (!agent->valid()) {
4084 char buffer[JVM_MAXPATHLEN];
4085 char ebuf[1024] = "";
4086 const char *name = agent->name();
4087 const char *msg = "Could not find agent library ";
4088
4089 // First check to see if agent is statically linked into executable
4090 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4091 library = agent->os_lib();
4092 } else if (agent->is_absolute_path()) {
4093 library = os::dll_load(name, ebuf, sizeof ebuf);
4094 if (library == NULL) {
4095 const char *sub_msg = " in absolute path, with error: ";
4096 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4097 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4098 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4099 // If we can't find the agent, exit.
4100 vm_exit_during_initialization(buf, NULL);
4101 FREE_C_HEAP_ARRAY(char, buf);
4102 }
4103 } else {
4104 // Try to load the agent from the standard dll directory
4105 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4106 name)) {
4107 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4108 }
4109 if (library == NULL) { // Try the library path directory.
4110 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4111 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4112 }
4113 if (library == NULL) {
4114 const char *sub_msg = " on the library path, with error: ";
4115 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4116
4117 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4118 strlen(ebuf) + strlen(sub_msg2) + 1;
4119 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4120 if (!agent->is_instrument_lib()) {
4121 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4122 } else {
4123 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4124 }
4125 // If we can't find the agent, exit.
4126 vm_exit_during_initialization(buf, NULL);
4127 FREE_C_HEAP_ARRAY(char, buf);
4128 }
4129 }
4130 }
4131 agent->set_os_lib(library);
4132 agent->set_valid();
4133 }
4134
4135 // Find the OnLoad function.
4136 on_load_entry =
4137 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4138 false,
4139 on_load_symbols,
4140 num_symbol_entries));
4141 return on_load_entry;
4142 }
4143
4144 // Find the JVM_OnLoad entry point
4145 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4146 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4147 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4148 }
4149
4150 // Find the Agent_OnLoad entry point
4151 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4152 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4153 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4154 }
4155
4156 // For backwards compatibility with -Xrun
4157 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4158 // treated like -agentpath:
4159 // Must be called before agent libraries are created
4160 void Threads::convert_vm_init_libraries_to_agents() {
4161 AgentLibrary* agent;
4162 AgentLibrary* next;
4163
4164 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4165 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4166 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4167
4168 // If there is an JVM_OnLoad function it will get called later,
4169 // otherwise see if there is an Agent_OnLoad
4170 if (on_load_entry == NULL) {
4171 on_load_entry = lookup_agent_on_load(agent);
4172 if (on_load_entry != NULL) {
4173 // switch it to the agent list -- so that Agent_OnLoad will be called,
4174 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4175 Arguments::convert_library_to_agent(agent);
4176 } else {
4177 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4178 }
4179 }
4180 }
4181 }
4182
4183 // Create agents for -agentlib: -agentpath: and converted -Xrun
4184 // Invokes Agent_OnLoad
4185 // Called very early -- before JavaThreads exist
4186 void Threads::create_vm_init_agents() {
4187 extern struct JavaVM_ main_vm;
4188 AgentLibrary* agent;
4189
4190 JvmtiExport::enter_onload_phase();
4191
4192 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4193 // CDS dumping does not support native JVMTI agent.
4194 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4195 if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4196 if(!agent->is_instrument_lib()) {
4197 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4198 } else if (!AllowArchivingWithJavaAgent) {
4199 vm_exit_during_cds_dumping(
4200 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4201 }
4202 }
4203
4204 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4205
4206 if (on_load_entry != NULL) {
4207 // Invoke the Agent_OnLoad function
4208 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4209 if (err != JNI_OK) {
4210 vm_exit_during_initialization("agent library failed to init", agent->name());
4211 }
4212 } else {
4213 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4214 }
4215 }
4216
4217 JvmtiExport::enter_primordial_phase();
4218 }
4219
4220 extern "C" {
4221 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4222 }
4223
4224 void Threads::shutdown_vm_agents() {
4225 // Send any Agent_OnUnload notifications
4226 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4227 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4228 extern struct JavaVM_ main_vm;
4229 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4230
4231 // Find the Agent_OnUnload function.
4232 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4233 os::find_agent_function(agent,
4234 false,
4235 on_unload_symbols,
4236 num_symbol_entries));
4237
4238 // Invoke the Agent_OnUnload function
4239 if (unload_entry != NULL) {
4240 JavaThread* thread = JavaThread::current();
4241 ThreadToNativeFromVM ttn(thread);
4242 HandleMark hm(thread);
4243 (*unload_entry)(&main_vm);
4244 }
4245 }
4246 }
4247
4248 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4249 // Invokes JVM_OnLoad
4250 void Threads::create_vm_init_libraries() {
4251 extern struct JavaVM_ main_vm;
4252 AgentLibrary* agent;
4253
4254 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4255 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4256
4257 if (on_load_entry != NULL) {
4258 // Invoke the JVM_OnLoad function
4259 JavaThread* thread = JavaThread::current();
4260 ThreadToNativeFromVM ttn(thread);
4261 HandleMark hm(thread);
4262 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4263 if (err != JNI_OK) {
4264 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4265 }
4266 } else {
4267 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4268 }
4269 }
4270 }
4271
4272
4273 // Last thread running calls java.lang.Shutdown.shutdown()
4274 void JavaThread::invoke_shutdown_hooks() {
4275 HandleMark hm(this);
4276
4277 // We could get here with a pending exception, if so clear it now.
4278 if (this->has_pending_exception()) {
4279 this->clear_pending_exception();
4280 }
4281
4282 EXCEPTION_MARK;
4283 Klass* shutdown_klass =
4284 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4285 THREAD);
4286 if (shutdown_klass != NULL) {
4287 // SystemDictionary::resolve_or_null will return null if there was
4288 // an exception. If we cannot load the Shutdown class, just don't
4289 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4290 // won't be run. Note that if a shutdown hook was registered,
4291 // the Shutdown class would have already been loaded
4292 // (Runtime.addShutdownHook will load it).
4293 JavaValue result(T_VOID);
4294 JavaCalls::call_static(&result,
4295 shutdown_klass,
4296 vmSymbols::shutdown_name(),
4297 vmSymbols::void_method_signature(),
4298 THREAD);
4299 }
4300 CLEAR_PENDING_EXCEPTION;
4301 }
4302
4303 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4304 // the program falls off the end of main(). Another VM exit path is through
4305 // vm_exit() when the program calls System.exit() to return a value or when
4306 // there is a serious error in VM. The two shutdown paths are not exactly
4307 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4308 // and VM_Exit op at VM level.
4309 //
4310 // Shutdown sequence:
4311 // + Shutdown native memory tracking if it is on
4312 // + Wait until we are the last non-daemon thread to execute
4313 // <-- every thing is still working at this moment -->
4314 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4315 // shutdown hooks
4316 // + Call before_exit(), prepare for VM exit
4317 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4318 // currently the only user of this mechanism is File.deleteOnExit())
4319 // > stop StatSampler, watcher thread, CMS threads,
4320 // post thread end and vm death events to JVMTI,
4321 // stop signal thread
4322 // + Call JavaThread::exit(), it will:
4323 // > release JNI handle blocks, remove stack guard pages
4324 // > remove this thread from Threads list
4325 // <-- no more Java code from this thread after this point -->
4326 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4327 // the compiler threads at safepoint
4328 // <-- do not use anything that could get blocked by Safepoint -->
4329 // + Disable tracing at JNI/JVM barriers
4330 // + Set _vm_exited flag for threads that are still running native code
4331 // + Call exit_globals()
4332 // > deletes tty
4333 // > deletes PerfMemory resources
4334 // + Delete this thread
4335 // + Return to caller
4336
4337 bool Threads::destroy_vm() {
4338 JavaThread* thread = JavaThread::current();
4339
4340 #ifdef ASSERT
4341 _vm_complete = false;
4342 #endif
4343 // Wait until we are the last non-daemon thread to execute
4344 { MonitorLocker nu(Threads_lock);
4345 while (Threads::number_of_non_daemon_threads() > 1)
4346 // This wait should make safepoint checks, wait without a timeout,
4347 // and wait as a suspend-equivalent condition.
4348 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4349 }
4350
4351 EventShutdown e;
4352 if (e.should_commit()) {
4353 e.set_reason("No remaining non-daemon Java threads");
4354 e.commit();
4355 }
4356
4357 // Hang forever on exit if we are reporting an error.
4358 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4359 os::infinite_sleep();
4360 }
4361 os::wait_for_keypress_at_exit();
4362
4363 // run Java level shutdown hooks
4364 thread->invoke_shutdown_hooks();
4365
4366 before_exit(thread);
4367
4368 thread->exit(true);
4369
4370 // Stop VM thread.
4371 {
4372 // 4945125 The vm thread comes to a safepoint during exit.
4373 // GC vm_operations can get caught at the safepoint, and the
4374 // heap is unparseable if they are caught. Grab the Heap_lock
4375 // to prevent this. The GC vm_operations will not be able to
4376 // queue until after the vm thread is dead. After this point,
4377 // we'll never emerge out of the safepoint before the VM exits.
4378
4379 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4380
4381 VMThread::wait_for_vm_thread_exit();
4382 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4383 VMThread::destroy();
4384 }
4385
4386 // Now, all Java threads are gone except daemon threads. Daemon threads
4387 // running Java code or in VM are stopped by the Safepoint. However,
4388 // daemon threads executing native code are still running. But they
4389 // will be stopped at native=>Java/VM barriers. Note that we can't
4390 // simply kill or suspend them, as it is inherently deadlock-prone.
4391
4392 VM_Exit::set_vm_exited();
4393
4394 // Clean up ideal graph printers after the VMThread has started
4395 // the final safepoint which will block all the Compiler threads.
4396 // Note that this Thread has already logically exited so the
4397 // clean_up() function's use of a JavaThreadIteratorWithHandle
4398 // would be a problem except set_vm_exited() has remembered the
4399 // shutdown thread which is granted a policy exception.
4400 #if defined(COMPILER2) && !defined(PRODUCT)
4401 IdealGraphPrinter::clean_up();
4402 #endif
4403
4404 notify_vm_shutdown();
4405
4406 // exit_globals() will delete tty
4407 exit_globals();
4408
4409 // We are after VM_Exit::set_vm_exited() so we can't call
4410 // thread->smr_delete() or we will block on the Threads_lock.
4411 // Deleting the shutdown thread here is safe because another
4412 // JavaThread cannot have an active ThreadsListHandle for
4413 // this JavaThread.
4414 delete thread;
4415
4416 #if INCLUDE_JVMCI
4417 if (JVMCICounterSize > 0) {
4418 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4419 }
4420 #endif
4421
4422 LogConfiguration::finalize();
4423
4424 return true;
4425 }
4426
4427
4428 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4429 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4430 return is_supported_jni_version(version);
4431 }
4432
4433
4434 jboolean Threads::is_supported_jni_version(jint version) {
4435 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4436 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4437 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4438 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4439 if (version == JNI_VERSION_9) return JNI_TRUE;
4440 if (version == JNI_VERSION_10) return JNI_TRUE;
4441 return JNI_FALSE;
4442 }
4443
4444
4445 void Threads::add(JavaThread* p, bool force_daemon) {
4446 // The threads lock must be owned at this point
4447 assert(Threads_lock->owned_by_self(), "must have threads lock");
4448
4449 BarrierSet::barrier_set()->on_thread_attach(p);
4450
4451 // Once a JavaThread is added to the Threads list, smr_delete() has
4452 // to be used to delete it. Otherwise we can just delete it directly.
4453 p->set_on_thread_list();
4454
4455 _number_of_threads++;
4456 oop threadObj = p->threadObj();
4457 bool daemon = true;
4458 // Bootstrapping problem: threadObj can be null for initial
4459 // JavaThread (or for threads attached via JNI)
4460 if ((!force_daemon) && !is_daemon((threadObj))) {
4461 _number_of_non_daemon_threads++;
4462 daemon = false;
4463 }
4464
4465 ThreadService::add_thread(p, daemon);
4466
4467 // Maintain fast thread list
4468 ThreadsSMRSupport::add_thread(p);
4469
4470 // Possible GC point.
4471 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4472 }
4473
4474 void Threads::remove(JavaThread* p, bool is_daemon) {
4475
4476 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4477 ObjectSynchronizer::om_flush(p);
4478
4479 // Extra scope needed for Thread_lock, so we can check
4480 // that we do not remove thread without safepoint code notice
4481 { MonitorLocker ml(Threads_lock);
4482
4483 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4484
4485 // Maintain fast thread list
4486 ThreadsSMRSupport::remove_thread(p);
4487
4488 _number_of_threads--;
4489 if (!is_daemon) {
4490 _number_of_non_daemon_threads--;
4491
4492 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4493 // on destroy_vm will wake up.
4494 if (number_of_non_daemon_threads() == 1) {
4495 ml.notify_all();
4496 }
4497 }
4498 ThreadService::remove_thread(p, is_daemon);
4499
4500 // Make sure that safepoint code disregard this thread. This is needed since
4501 // the thread might mess around with locks after this point. This can cause it
4502 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4503 // of this thread since it is removed from the queue.
4504 p->set_terminated_value();
4505 } // unlock Threads_lock
4506
4507 // Since Events::log uses a lock, we grab it outside the Threads_lock
4508 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4509 }
4510
4511 // Operations on the Threads list for GC. These are not explicitly locked,
4512 // but the garbage collector must provide a safe context for them to run.
4513 // In particular, these things should never be called when the Threads_lock
4514 // is held by some other thread. (Note: the Safepoint abstraction also
4515 // uses the Threads_lock to guarantee this property. It also makes sure that
4516 // all threads gets blocked when exiting or starting).
4517
4518 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4519 ALL_JAVA_THREADS(p) {
4520 p->oops_do(f, cf);
4521 }
4522 VMThread::vm_thread()->oops_do(f, cf);
4523 }
4524
4525 void Threads::change_thread_claim_token() {
4526 if (++_thread_claim_token == 0) {
4527 // On overflow of the token counter, there is a risk of future
4528 // collisions between a new global token value and a stale token
4529 // for a thread, because not all iterations visit all threads.
4530 // (Though it's pretty much a theoretical concern for non-trivial
4531 // token counter sizes.) To deal with the possibility, reset all
4532 // the thread tokens to zero on global token overflow.
4533 struct ResetClaims : public ThreadClosure {
4534 virtual void do_thread(Thread* t) {
4535 t->claim_threads_do(false, 0);
4536 }
4537 } reset_claims;
4538 Threads::threads_do(&reset_claims);
4539 // On overflow, update the global token to non-zero, to
4540 // avoid the special "never claimed" initial thread value.
4541 _thread_claim_token = 1;
4542 }
4543 }
4544
4545 #ifdef ASSERT
4546 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4547 const uintx token = t->threads_do_token();
4548 assert(token == expected,
4549 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4550 UINTX_FORMAT, kind, p2i(t), token, expected);
4551 }
4552
4553 void Threads::assert_all_threads_claimed() {
4554 ALL_JAVA_THREADS(p) {
4555 assert_thread_claimed("Thread", p, _thread_claim_token);
4556 }
4557 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4558 }
4559 #endif // ASSERT
4560
4561 class ParallelOopsDoThreadClosure : public ThreadClosure {
4562 private:
4563 OopClosure* _f;
4564 CodeBlobClosure* _cf;
4565 public:
4566 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4567 void do_thread(Thread* t) {
4568 t->oops_do(_f, _cf);
4569 }
4570 };
4571
4572 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4573 ParallelOopsDoThreadClosure tc(f, cf);
4574 possibly_parallel_threads_do(is_par, &tc);
4575 }
4576
4577 void Threads::nmethods_do(CodeBlobClosure* cf) {
4578 ALL_JAVA_THREADS(p) {
4579 // This is used by the code cache sweeper to mark nmethods that are active
4580 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4581 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4582 if(!p->is_Code_cache_sweeper_thread()) {
4583 p->nmethods_do(cf);
4584 }
4585 }
4586 }
4587
4588 void Threads::metadata_do(MetadataClosure* f) {
4589 ALL_JAVA_THREADS(p) {
4590 p->metadata_do(f);
4591 }
4592 }
4593
4594 class ThreadHandlesClosure : public ThreadClosure {
4595 void (*_f)(Metadata*);
4596 public:
4597 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4598 virtual void do_thread(Thread* thread) {
4599 thread->metadata_handles_do(_f);
4600 }
4601 };
4602
4603 void Threads::metadata_handles_do(void f(Metadata*)) {
4604 // Only walk the Handles in Thread.
4605 ThreadHandlesClosure handles_closure(f);
4606 threads_do(&handles_closure);
4607 }
4608
4609 void Threads::deoptimized_wrt_marked_nmethods() {
4610 ALL_JAVA_THREADS(p) {
4611 p->deoptimized_wrt_marked_nmethods();
4612 }
4613 }
4614
4615
4616 // Get count Java threads that are waiting to enter the specified monitor.
4617 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4618 int count,
4619 address monitor) {
4620 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4621
4622 int i = 0;
4623 DO_JAVA_THREADS(t_list, p) {
4624 if (!p->can_call_java()) continue;
4625
4626 address pending = (address)p->current_pending_monitor();
4627 if (pending == monitor) { // found a match
4628 if (i < count) result->append(p); // save the first count matches
4629 i++;
4630 }
4631 }
4632
4633 return result;
4634 }
4635
4636
4637 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4638 address owner) {
4639 // NULL owner means not locked so we can skip the search
4640 if (owner == NULL) return NULL;
4641
4642 DO_JAVA_THREADS(t_list, p) {
4643 // first, see if owner is the address of a Java thread
4644 if (owner == (address)p) return p;
4645 }
4646
4647 // Cannot assert on lack of success here since this function may be
4648 // used by code that is trying to report useful problem information
4649 // like deadlock detection.
4650 if (UseHeavyMonitors) return NULL;
4651
4652 // If we didn't find a matching Java thread and we didn't force use of
4653 // heavyweight monitors, then the owner is the stack address of the
4654 // Lock Word in the owning Java thread's stack.
4655 //
4656 JavaThread* the_owner = NULL;
4657 DO_JAVA_THREADS(t_list, q) {
4658 if (q->is_lock_owned(owner)) {
4659 the_owner = q;
4660 break;
4661 }
4662 }
4663
4664 // cannot assert on lack of success here; see above comment
4665 return the_owner;
4666 }
4667
4668 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4669 void Threads::print_on(outputStream* st, bool print_stacks,
4670 bool internal_format, bool print_concurrent_locks,
4671 bool print_extended_info) {
4672 char buf[32];
4673 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4674
4675 st->print_cr("Full thread dump %s (%s %s):",
4676 VM_Version::vm_name(),
4677 VM_Version::vm_release(),
4678 VM_Version::vm_info_string());
4679 st->cr();
4680
4681 #if INCLUDE_SERVICES
4682 // Dump concurrent locks
4683 ConcurrentLocksDump concurrent_locks;
4684 if (print_concurrent_locks) {
4685 concurrent_locks.dump_at_safepoint();
4686 }
4687 #endif // INCLUDE_SERVICES
4688
4689 ThreadsSMRSupport::print_info_on(st);
4690 st->cr();
4691
4692 ALL_JAVA_THREADS(p) {
4693 ResourceMark rm;
4694 p->print_on(st, print_extended_info);
4695 if (print_stacks) {
4696 if (internal_format) {
4697 p->trace_stack();
4698 } else {
4699 p->print_stack_on(st);
4700 }
4701 }
4702 st->cr();
4703 #if INCLUDE_SERVICES
4704 if (print_concurrent_locks) {
4705 concurrent_locks.print_locks_on(p, st);
4706 }
4707 #endif // INCLUDE_SERVICES
4708 }
4709
4710 VMThread::vm_thread()->print_on(st);
4711 st->cr();
4712 Universe::heap()->print_gc_threads_on(st);
4713 WatcherThread* wt = WatcherThread::watcher_thread();
4714 if (wt != NULL) {
4715 wt->print_on(st);
4716 st->cr();
4717 }
4718
4719 st->flush();
4720 }
4721
4722 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4723 int buflen, bool* found_current) {
4724 if (this_thread != NULL) {
4725 bool is_current = (current == this_thread);
4726 *found_current = *found_current || is_current;
4727 st->print("%s", is_current ? "=>" : " ");
4728
4729 st->print(PTR_FORMAT, p2i(this_thread));
4730 st->print(" ");
4731 this_thread->print_on_error(st, buf, buflen);
4732 st->cr();
4733 }
4734 }
4735
4736 class PrintOnErrorClosure : public ThreadClosure {
4737 outputStream* _st;
4738 Thread* _current;
4739 char* _buf;
4740 int _buflen;
4741 bool* _found_current;
4742 public:
4743 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4744 int buflen, bool* found_current) :
4745 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4746
4747 virtual void do_thread(Thread* thread) {
4748 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4749 }
4750 };
4751
4752 // Threads::print_on_error() is called by fatal error handler. It's possible
4753 // that VM is not at safepoint and/or current thread is inside signal handler.
4754 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4755 // memory (even in resource area), it might deadlock the error handler.
4756 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4757 int buflen) {
4758 ThreadsSMRSupport::print_info_on(st);
4759 st->cr();
4760
4761 bool found_current = false;
4762 st->print_cr("Java Threads: ( => current thread )");
4763 ALL_JAVA_THREADS(thread) {
4764 print_on_error(thread, st, current, buf, buflen, &found_current);
4765 }
4766 st->cr();
4767
4768 st->print_cr("Other Threads:");
4769 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4770 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4771
4772 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4773 Universe::heap()->gc_threads_do(&print_closure);
4774
4775 if (!found_current) {
4776 st->cr();
4777 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4778 current->print_on_error(st, buf, buflen);
4779 st->cr();
4780 }
4781 st->cr();
4782
4783 st->print_cr("Threads with active compile tasks:");
4784 print_threads_compiling(st, buf, buflen);
4785 }
4786
4787 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4788 ALL_JAVA_THREADS(thread) {
4789 if (thread->is_Compiler_thread()) {
4790 CompilerThread* ct = (CompilerThread*) thread;
4791
4792 // Keep task in local variable for NULL check.
4793 // ct->_task might be set to NULL by concurring compiler thread
4794 // because it completed the compilation. The task is never freed,
4795 // though, just returned to a free list.
4796 CompileTask* task = ct->task();
4797 if (task != NULL) {
4798 thread->print_name_on_error(st, buf, buflen);
4799 st->print(" ");
4800 task->print(st, NULL, short_form, true);
4801 }
4802 }
4803 }
4804 }
4805
4806
4807 // Internal SpinLock and Mutex
4808 // Based on ParkEvent
4809
4810 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4811 //
4812 // We employ SpinLocks _only for low-contention, fixed-length
4813 // short-duration critical sections where we're concerned
4814 // about native mutex_t or HotSpot Mutex:: latency.
4815 // The mux construct provides a spin-then-block mutual exclusion
4816 // mechanism.
4817 //
4818 // Testing has shown that contention on the ListLock guarding gFreeList
4819 // is common. If we implement ListLock as a simple SpinLock it's common
4820 // for the JVM to devolve to yielding with little progress. This is true
4821 // despite the fact that the critical sections protected by ListLock are
4822 // extremely short.
4823 //
4824 // TODO-FIXME: ListLock should be of type SpinLock.
4825 // We should make this a 1st-class type, integrated into the lock
4826 // hierarchy as leaf-locks. Critically, the SpinLock structure
4827 // should have sufficient padding to avoid false-sharing and excessive
4828 // cache-coherency traffic.
4829
4830
4831 typedef volatile int SpinLockT;
4832
4833 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4834 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4835 return; // normal fast-path return
4836 }
4837
4838 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4839 int ctr = 0;
4840 int Yields = 0;
4841 for (;;) {
4842 while (*adr != 0) {
4843 ++ctr;
4844 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4845 if (Yields > 5) {
4846 os::naked_short_sleep(1);
4847 } else {
4848 os::naked_yield();
4849 ++Yields;
4850 }
4851 } else {
4852 SpinPause();
4853 }
4854 }
4855 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4856 }
4857 }
4858
4859 void Thread::SpinRelease(volatile int * adr) {
4860 assert(*adr != 0, "invariant");
4861 OrderAccess::fence(); // guarantee at least release consistency.
4862 // Roach-motel semantics.
4863 // It's safe if subsequent LDs and STs float "up" into the critical section,
4864 // but prior LDs and STs within the critical section can't be allowed
4865 // to reorder or float past the ST that releases the lock.
4866 // Loads and stores in the critical section - which appear in program
4867 // order before the store that releases the lock - must also appear
4868 // before the store that releases the lock in memory visibility order.
4869 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4870 // the ST of 0 into the lock-word which releases the lock, so fence
4871 // more than covers this on all platforms.
4872 *adr = 0;
4873 }
4874
4875 // muxAcquire and muxRelease:
4876 //
4877 // * muxAcquire and muxRelease support a single-word lock-word construct.
4878 // The LSB of the word is set IFF the lock is held.
4879 // The remainder of the word points to the head of a singly-linked list
4880 // of threads blocked on the lock.
4881 //
4882 // * The current implementation of muxAcquire-muxRelease uses its own
4883 // dedicated Thread._MuxEvent instance. If we're interested in
4884 // minimizing the peak number of extant ParkEvent instances then
4885 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4886 // as certain invariants were satisfied. Specifically, care would need
4887 // to be taken with regards to consuming unpark() "permits".
4888 // A safe rule of thumb is that a thread would never call muxAcquire()
4889 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4890 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4891 // consume an unpark() permit intended for monitorenter, for instance.
4892 // One way around this would be to widen the restricted-range semaphore
4893 // implemented in park(). Another alternative would be to provide
4894 // multiple instances of the PlatformEvent() for each thread. One
4895 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4896 //
4897 // * Usage:
4898 // -- Only as leaf locks
4899 // -- for short-term locking only as muxAcquire does not perform
4900 // thread state transitions.
4901 //
4902 // Alternatives:
4903 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4904 // but with parking or spin-then-park instead of pure spinning.
4905 // * Use Taura-Oyama-Yonenzawa locks.
4906 // * It's possible to construct a 1-0 lock if we encode the lockword as
4907 // (List,LockByte). Acquire will CAS the full lockword while Release
4908 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4909 // acquiring threads use timers (ParkTimed) to detect and recover from
4910 // the stranding window. Thread/Node structures must be aligned on 256-byte
4911 // boundaries by using placement-new.
4912 // * Augment MCS with advisory back-link fields maintained with CAS().
4913 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4914 // The validity of the backlinks must be ratified before we trust the value.
4915 // If the backlinks are invalid the exiting thread must back-track through the
4916 // the forward links, which are always trustworthy.
4917 // * Add a successor indication. The LockWord is currently encoded as
4918 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4919 // to provide the usual futile-wakeup optimization.
4920 // See RTStt for details.
4921 //
4922
4923
4924 const intptr_t LOCKBIT = 1;
4925
4926 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4927 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4928 if (w == 0) return;
4929 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4930 return;
4931 }
4932
4933 ParkEvent * const Self = Thread::current()->_MuxEvent;
4934 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4935 for (;;) {
4936 int its = (os::is_MP() ? 100 : 0) + 1;
4937
4938 // Optional spin phase: spin-then-park strategy
4939 while (--its >= 0) {
4940 w = *Lock;
4941 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4942 return;
4943 }
4944 }
4945
4946 Self->reset();
4947 Self->OnList = intptr_t(Lock);
4948 // The following fence() isn't _strictly necessary as the subsequent
4949 // CAS() both serializes execution and ratifies the fetched *Lock value.
4950 OrderAccess::fence();
4951 for (;;) {
4952 w = *Lock;
4953 if ((w & LOCKBIT) == 0) {
4954 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4955 Self->OnList = 0; // hygiene - allows stronger asserts
4956 return;
4957 }
4958 continue; // Interference -- *Lock changed -- Just retry
4959 }
4960 assert(w & LOCKBIT, "invariant");
4961 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4962 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4963 }
4964
4965 while (Self->OnList != 0) {
4966 Self->park();
4967 }
4968 }
4969 }
4970
4971 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4972 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4973 if (w == 0) return;
4974 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4975 return;
4976 }
4977
4978 ParkEvent * ReleaseAfter = NULL;
4979 if (ev == NULL) {
4980 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4981 }
4982 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4983 for (;;) {
4984 guarantee(ev->OnList == 0, "invariant");
4985 int its = (os::is_MP() ? 100 : 0) + 1;
4986
4987 // Optional spin phase: spin-then-park strategy
4988 while (--its >= 0) {
4989 w = *Lock;
4990 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4991 if (ReleaseAfter != NULL) {
4992 ParkEvent::Release(ReleaseAfter);
4993 }
4994 return;
4995 }
4996 }
4997
4998 ev->reset();
4999 ev->OnList = intptr_t(Lock);
5000 // The following fence() isn't _strictly necessary as the subsequent
5001 // CAS() both serializes execution and ratifies the fetched *Lock value.
5002 OrderAccess::fence();
5003 for (;;) {
5004 w = *Lock;
5005 if ((w & LOCKBIT) == 0) {
5006 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5007 ev->OnList = 0;
5008 // We call ::Release while holding the outer lock, thus
5009 // artificially lengthening the critical section.
5010 // Consider deferring the ::Release() until the subsequent unlock(),
5011 // after we've dropped the outer lock.
5012 if (ReleaseAfter != NULL) {
5013 ParkEvent::Release(ReleaseAfter);
5014 }
5015 return;
5016 }
5017 continue; // Interference -- *Lock changed -- Just retry
5018 }
5019 assert(w & LOCKBIT, "invariant");
5020 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5021 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5022 }
5023
5024 while (ev->OnList != 0) {
5025 ev->park();
5026 }
5027 }
5028 }
5029
5030 // Release() must extract a successor from the list and then wake that thread.
5031 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5032 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5033 // Release() would :
5034 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5035 // (B) Extract a successor from the private list "in-hand"
5036 // (C) attempt to CAS() the residual back into *Lock over null.
5037 // If there were any newly arrived threads and the CAS() would fail.
5038 // In that case Release() would detach the RATs, re-merge the list in-hand
5039 // with the RATs and repeat as needed. Alternately, Release() might
5040 // detach and extract a successor, but then pass the residual list to the wakee.
5041 // The wakee would be responsible for reattaching and remerging before it
5042 // competed for the lock.
5043 //
5044 // Both "pop" and DMR are immune from ABA corruption -- there can be
5045 // multiple concurrent pushers, but only one popper or detacher.
5046 // This implementation pops from the head of the list. This is unfair,
5047 // but tends to provide excellent throughput as hot threads remain hot.
5048 // (We wake recently run threads first).
5049 //
5050 // All paths through muxRelease() will execute a CAS.
5051 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5052 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5053 // executed within the critical section are complete and globally visible before the
5054 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5055 void Thread::muxRelease(volatile intptr_t * Lock) {
5056 for (;;) {
5057 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5058 assert(w & LOCKBIT, "invariant");
5059 if (w == LOCKBIT) return;
5060 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5061 assert(List != NULL, "invariant");
5062 assert(List->OnList == intptr_t(Lock), "invariant");
5063 ParkEvent * const nxt = List->ListNext;
5064 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5065
5066 // The following CAS() releases the lock and pops the head element.
5067 // The CAS() also ratifies the previously fetched lock-word value.
5068 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5069 continue;
5070 }
5071 List->OnList = 0;
5072 OrderAccess::fence();
5073 List->unpark();
5074 return;
5075 }
5076 }
5077
5078
5079 void Threads::verify() {
5080 ALL_JAVA_THREADS(p) {
5081 p->verify();
5082 }
5083 VMThread* thread = VMThread::vm_thread();
5084 if (thread != NULL) thread->verify();
5085 }