1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "aot/aotLoader.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/javaClasses.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/scopeDesc.hpp"
35 #include "compiler/compileBroker.hpp"
36 #include "compiler/compileTask.hpp"
37 #include "gc/shared/barrierSet.hpp"
38 #include "gc/shared/gcId.hpp"
39 #include "gc/shared/gcLocker.inline.hpp"
40 #include "gc/shared/workgroup.hpp"
41 #include "interpreter/interpreter.hpp"
42 #include "interpreter/linkResolver.hpp"
43 #include "interpreter/oopMapCache.hpp"
44 #include "jfr/jfrEvents.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "runtime/arguments.hpp"
65 #include "runtime/atomic.hpp"
66 #include "runtime/biasedLocking.hpp"
67 #include "runtime/fieldDescriptor.inline.hpp"
68 #include "runtime/flags/jvmFlagConstraintList.hpp"
69 #include "runtime/flags/jvmFlagRangeList.hpp"
70 #include "runtime/flags/jvmFlagWriteableList.hpp"
71 #include "runtime/deoptimization.hpp"
72 #include "runtime/frame.inline.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/handshake.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/jniHandles.inline.hpp"
80 #include "runtime/jniPeriodicChecker.hpp"
81 #include "runtime/memprofiler.hpp"
82 #include "runtime/mutexLocker.hpp"
83 #include "runtime/objectMonitor.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/osThread.hpp"
86 #include "runtime/prefetch.inline.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/safepointMechanism.inline.hpp"
89 #include "runtime/safepointVerifiers.hpp"
90 #include "runtime/sharedRuntime.hpp"
91 #include "runtime/statSampler.hpp"
92 #include "runtime/stubRoutines.hpp"
93 #include "runtime/sweeper.hpp"
94 #include "runtime/task.hpp"
95 #include "runtime/thread.inline.hpp"
96 #include "runtime/threadCritical.hpp"
97 #include "runtime/threadSMR.inline.hpp"
98 #include "runtime/threadStatisticalInfo.hpp"
99 #include "runtime/timer.hpp"
100 #include "runtime/timerTrace.hpp"
101 #include "runtime/vframe.inline.hpp"
102 #include "runtime/vframeArray.hpp"
103 #include "runtime/vframe_hp.hpp"
104 #include "runtime/vmThread.hpp"
105 #include "runtime/vmOperations.hpp"
106 #include "runtime/vm_version.hpp"
107 #include "services/attachListener.hpp"
108 #include "services/management.hpp"
109 #include "services/memTracker.hpp"
110 #include "services/threadService.hpp"
111 #include "utilities/align.hpp"
112 #include "utilities/copy.hpp"
113 #include "utilities/defaultStream.hpp"
114 #include "utilities/dtrace.hpp"
115 #include "utilities/events.hpp"
116 #include "utilities/macros.hpp"
117 #include "utilities/preserveException.hpp"
118 #include "utilities/singleWriterSynchronizer.hpp"
119 #include "utilities/vmError.hpp"
120 #if INCLUDE_JVMCI
121 #include "jvmci/jvmci.hpp"
122 #include "jvmci/jvmciEnv.hpp"
123 #endif
124 #ifdef COMPILER1
125 #include "c1/c1_Compiler.hpp"
126 #endif
127 #ifdef COMPILER2
128 #include "opto/c2compiler.hpp"
129 #include "opto/idealGraphPrinter.hpp"
130 #endif
131 #if INCLUDE_RTM_OPT
132 #include "runtime/rtmLocking.hpp"
133 #endif
134 #if INCLUDE_JFR
135 #include "jfr/jfr.hpp"
136 #endif
137
138 // Initialization after module runtime initialization
139 void universe_post_module_init(); // must happen after call_initPhase2
140
141 #ifdef DTRACE_ENABLED
142
143 // Only bother with this argument setup if dtrace is available
144
145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
147
148 #define DTRACE_THREAD_PROBE(probe, javathread) \
149 { \
150 ResourceMark rm(this); \
151 int len = 0; \
152 const char* name = (javathread)->get_thread_name(); \
153 len = strlen(name); \
154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
155 (char *) name, len, \
156 java_lang_Thread::thread_id((javathread)->threadObj()), \
157 (uintptr_t) (javathread)->osthread()->thread_id(), \
158 java_lang_Thread::is_daemon((javathread)->threadObj())); \
159 }
160
161 #else // ndef DTRACE_ENABLED
162
163 #define DTRACE_THREAD_PROBE(probe, javathread)
164
165 #endif // ndef DTRACE_ENABLED
166
167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
168 // Current thread is maintained as a thread-local variable
169 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
170 #endif
171
172 // ======= Thread ========
173 // Support for forcing alignment of thread objects for biased locking
174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
175 if (UseBiasedLocking) {
176 const size_t alignment = markWord::biased_lock_alignment;
177 size_t aligned_size = size + (alignment - sizeof(intptr_t));
178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
179 : AllocateHeap(aligned_size, flags, CURRENT_PC,
180 AllocFailStrategy::RETURN_NULL);
181 void* aligned_addr = align_up(real_malloc_addr, alignment);
182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
184 "JavaThread alignment code overflowed allocated storage");
185 if (aligned_addr != real_malloc_addr) {
186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
187 p2i(real_malloc_addr),
188 p2i(aligned_addr));
189 }
190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
191 return aligned_addr;
192 } else {
193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
195 }
196 }
197
198 void Thread::operator delete(void* p) {
199 if (UseBiasedLocking) {
200 FreeHeap(((Thread*) p)->_real_malloc_address);
201 } else {
202 FreeHeap(p);
203 }
204 }
205
206 void JavaThread::smr_delete() {
207 if (_on_thread_list) {
208 ThreadsSMRSupport::smr_delete(this);
209 } else {
210 delete this;
211 }
212 }
213
214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
215 // JavaThread
216
217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
218
219 Thread::Thread() {
220
221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
222
223 // stack and get_thread
224 set_stack_base(NULL);
225 set_stack_size(0);
226 set_lgrp_id(-1);
227 DEBUG_ONLY(clear_suspendible_thread();)
228
229 // allocated data structures
230 set_osthread(NULL);
231 set_resource_area(new (mtThread)ResourceArea());
232 DEBUG_ONLY(_current_resource_mark = NULL;)
233 set_handle_area(new (mtThread) HandleArea(NULL));
234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
235 set_active_handles(NULL);
236 set_free_handle_block(NULL);
237 set_last_handle_mark(NULL);
238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
239
240 // Initial value of zero ==> never claimed.
241 _threads_do_token = 0;
242 _threads_hazard_ptr = NULL;
243 _threads_list_ptr = NULL;
244 _nested_threads_hazard_ptr_cnt = 0;
245 _rcu_counter = 0;
246
247 // the handle mark links itself to last_handle_mark
248 new HandleMark(this);
249
250 // plain initialization
251 debug_only(_owned_locks = NULL;)
252 NOT_PRODUCT(_no_safepoint_count = 0;)
253 NOT_PRODUCT(_skip_gcalot = false;)
254 _jvmti_env_iteration_count = 0;
255 set_allocated_bytes(0);
256 _vm_operation_started_count = 0;
257 _vm_operation_completed_count = 0;
258 _current_pending_monitor = NULL;
259 _current_pending_monitor_is_from_java = true;
260 _current_waiting_monitor = NULL;
261 _current_pending_raw_monitor = NULL;
262 _num_nested_signal = 0;
263 om_free_list = NULL;
264 om_free_count = 0;
265 om_free_provision = 32;
266 om_in_use_list = NULL;
267 om_in_use_count = 0;
268
269 #ifdef ASSERT
270 _visited_for_critical_count = false;
271 #endif
272
273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
274 Monitor::_safepoint_check_sometimes);
275 _suspend_flags = 0;
276
277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
278 _hashStateX = os::random();
279 _hashStateY = 842502087;
280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
281 _hashStateW = 273326509;
282
283 _OnTrap = 0;
284 _Stalled = 0;
285 _TypeTag = 0x2BAD;
286
287 // Many of the following fields are effectively final - immutable
288 // Note that nascent threads can't use the Native Monitor-Mutex
289 // construct until the _MutexEvent is initialized ...
290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
291 // we might instead use a stack of ParkEvents that we could provision on-demand.
292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
293 // and ::Release()
294 _ParkEvent = ParkEvent::Allocate(this);
295 _MuxEvent = ParkEvent::Allocate(this);
296
297 #ifdef CHECK_UNHANDLED_OOPS
298 if (CheckUnhandledOops) {
299 _unhandled_oops = new UnhandledOops(this);
300 }
301 #endif // CHECK_UNHANDLED_OOPS
302 #ifdef ASSERT
303 if (UseBiasedLocking) {
304 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
307 "bug in forced alignment of thread objects");
308 }
309 #endif // ASSERT
310
311 // Notify the barrier set that a thread is being created. The initial
312 // thread is created before the barrier set is available. The call to
313 // BarrierSet::on_thread_create() for this thread is therefore deferred
314 // to BarrierSet::set_barrier_set().
315 BarrierSet* const barrier_set = BarrierSet::barrier_set();
316 if (barrier_set != NULL) {
317 barrier_set->on_thread_create(this);
318 } else {
319 // Only the main thread should be created before the barrier set
320 // and that happens just before Thread::current is set. No other thread
321 // can attach as the VM is not created yet, so they can't execute this code.
322 // If the main thread creates other threads before the barrier set that is an error.
323 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
324 }
325 }
326
327 void Thread::initialize_thread_current() {
328 #ifndef USE_LIBRARY_BASED_TLS_ONLY
329 assert(_thr_current == NULL, "Thread::current already initialized");
330 _thr_current = this;
331 #endif
332 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
333 ThreadLocalStorage::set_thread(this);
334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
335 }
336
337 void Thread::clear_thread_current() {
338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
339 #ifndef USE_LIBRARY_BASED_TLS_ONLY
340 _thr_current = NULL;
341 #endif
342 ThreadLocalStorage::set_thread(NULL);
343 }
344
345 void Thread::record_stack_base_and_size() {
346 // Note: at this point, Thread object is not yet initialized. Do not rely on
347 // any members being initialized. Do not rely on Thread::current() being set.
348 // If possible, refrain from doing anything which may crash or assert since
349 // quite probably those crash dumps will be useless.
350 set_stack_base(os::current_stack_base());
351 set_stack_size(os::current_stack_size());
352
353 #ifdef SOLARIS
354 if (os::is_primordial_thread()) {
355 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
356 }
357 #endif
358
359 // Set stack limits after thread is initialized.
360 if (is_Java_thread()) {
361 ((JavaThread*) this)->set_stack_overflow_limit();
362 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
363 }
364 }
365
366 #if INCLUDE_NMT
367 void Thread::register_thread_stack_with_NMT() {
368 MemTracker::record_thread_stack(stack_end(), stack_size());
369 }
370 #endif // INCLUDE_NMT
371
372 void Thread::call_run() {
373 DEBUG_ONLY(_run_state = CALL_RUN;)
374
375 // At this point, Thread object should be fully initialized and
376 // Thread::current() should be set.
377
378 assert(Thread::current_or_null() != NULL, "current thread is unset");
379 assert(Thread::current_or_null() == this, "current thread is wrong");
380
381 // Perform common initialization actions
382
383 register_thread_stack_with_NMT();
384
385 JFR_ONLY(Jfr::on_thread_start(this);)
386
387 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
388 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
389 os::current_thread_id(), p2i(stack_base() - stack_size()),
390 p2i(stack_base()), stack_size()/1024);
391
392 // Perform <ChildClass> initialization actions
393 DEBUG_ONLY(_run_state = PRE_RUN;)
394 this->pre_run();
395
396 // Invoke <ChildClass>::run()
397 DEBUG_ONLY(_run_state = RUN;)
398 this->run();
399 // Returned from <ChildClass>::run(). Thread finished.
400
401 // Perform common tear-down actions
402
403 assert(Thread::current_or_null() != NULL, "current thread is unset");
404 assert(Thread::current_or_null() == this, "current thread is wrong");
405
406 // Perform <ChildClass> tear-down actions
407 DEBUG_ONLY(_run_state = POST_RUN;)
408 this->post_run();
409
410 // Note: at this point the thread object may already have deleted itself,
411 // so from here on do not dereference *this*. Not all thread types currently
412 // delete themselves when they terminate. But no thread should ever be deleted
413 // asynchronously with respect to its termination - that is what _run_state can
414 // be used to check.
415
416 assert(Thread::current_or_null() == NULL, "current thread still present");
417 }
418
419 Thread::~Thread() {
420
421 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
422 // get started due to errors etc. Any active thread should at least reach post_run
423 // before it is deleted (usually in post_run()).
424 assert(_run_state == PRE_CALL_RUN ||
425 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
426 "_run_state=%d", (int)_run_state);
427
428 // Notify the barrier set that a thread is being destroyed. Note that a barrier
429 // set might not be available if we encountered errors during bootstrapping.
430 BarrierSet* const barrier_set = BarrierSet::barrier_set();
431 if (barrier_set != NULL) {
432 barrier_set->on_thread_destroy(this);
433 }
434
435 // stack_base can be NULL if the thread is never started or exited before
436 // record_stack_base_and_size called. Although, we would like to ensure
437 // that all started threads do call record_stack_base_and_size(), there is
438 // not proper way to enforce that.
439 #if INCLUDE_NMT
440 if (_stack_base != NULL) {
441 MemTracker::release_thread_stack(stack_end(), stack_size());
442 #ifdef ASSERT
443 set_stack_base(NULL);
444 #endif
445 }
446 #endif // INCLUDE_NMT
447
448 // deallocate data structures
449 delete resource_area();
450 // since the handle marks are using the handle area, we have to deallocated the root
451 // handle mark before deallocating the thread's handle area,
452 assert(last_handle_mark() != NULL, "check we have an element");
453 delete last_handle_mark();
454 assert(last_handle_mark() == NULL, "check we have reached the end");
455
456 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
457 // We NULL out the fields for good hygiene.
458 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
459 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
460
461 delete handle_area();
462 delete metadata_handles();
463
464 // SR_handler uses this as a termination indicator -
465 // needs to happen before os::free_thread()
466 delete _SR_lock;
467 _SR_lock = NULL;
468
469 // osthread() can be NULL, if creation of thread failed.
470 if (osthread() != NULL) os::free_thread(osthread());
471
472 // Clear Thread::current if thread is deleting itself and it has not
473 // already been done. This must be done before the memory is deallocated.
474 // Needed to ensure JNI correctly detects non-attached threads.
475 if (this == Thread::current_or_null()) {
476 Thread::clear_thread_current();
477 }
478
479 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
480 }
481
482 #ifdef ASSERT
483 // A JavaThread is considered "dangling" if it is not the current
484 // thread, has been added the Threads list, the system is not at a
485 // safepoint and the Thread is not "protected".
486 //
487 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
488 assert(!thread->is_Java_thread() || Thread::current() == thread ||
489 !((JavaThread *) thread)->on_thread_list() ||
490 SafepointSynchronize::is_at_safepoint() ||
491 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
492 "possibility of dangling Thread pointer");
493 }
494 #endif
495
496 ThreadPriority Thread::get_priority(const Thread* const thread) {
497 ThreadPriority priority;
498 // Can return an error!
499 (void)os::get_priority(thread, priority);
500 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
501 return priority;
502 }
503
504 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
505 debug_only(check_for_dangling_thread_pointer(thread);)
506 // Can return an error!
507 (void)os::set_priority(thread, priority);
508 }
509
510
511 void Thread::start(Thread* thread) {
512 // Start is different from resume in that its safety is guaranteed by context or
513 // being called from a Java method synchronized on the Thread object.
514 if (!DisableStartThread) {
515 if (thread->is_Java_thread()) {
516 // Initialize the thread state to RUNNABLE before starting this thread.
517 // Can not set it after the thread started because we do not know the
518 // exact thread state at that time. It could be in MONITOR_WAIT or
519 // in SLEEPING or some other state.
520 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
521 java_lang_Thread::RUNNABLE);
522 }
523 os::start_thread(thread);
524 }
525 }
526
527 // Enqueue a VM_Operation to do the job for us - sometime later
528 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
529 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
530 VMThread::execute(vm_stop);
531 }
532
533
534 // Check if an external suspend request has completed (or has been
535 // cancelled). Returns true if the thread is externally suspended and
536 // false otherwise.
537 //
538 // The bits parameter returns information about the code path through
539 // the routine. Useful for debugging:
540 //
541 // set in is_ext_suspend_completed():
542 // 0x00000001 - routine was entered
543 // 0x00000010 - routine return false at end
544 // 0x00000100 - thread exited (return false)
545 // 0x00000200 - suspend request cancelled (return false)
546 // 0x00000400 - thread suspended (return true)
547 // 0x00001000 - thread is in a suspend equivalent state (return true)
548 // 0x00002000 - thread is native and walkable (return true)
549 // 0x00004000 - thread is native_trans and walkable (needed retry)
550 //
551 // set in wait_for_ext_suspend_completion():
552 // 0x00010000 - routine was entered
553 // 0x00020000 - suspend request cancelled before loop (return false)
554 // 0x00040000 - thread suspended before loop (return true)
555 // 0x00080000 - suspend request cancelled in loop (return false)
556 // 0x00100000 - thread suspended in loop (return true)
557 // 0x00200000 - suspend not completed during retry loop (return false)
558
559 // Helper class for tracing suspend wait debug bits.
560 //
561 // 0x00000100 indicates that the target thread exited before it could
562 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
563 // 0x00080000 each indicate a cancelled suspend request so they don't
564 // count as wait failures either.
565 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
566
567 class TraceSuspendDebugBits : public StackObj {
568 private:
569 JavaThread * jt;
570 bool is_wait;
571 bool called_by_wait; // meaningful when !is_wait
572 uint32_t * bits;
573
574 public:
575 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
576 uint32_t *_bits) {
577 jt = _jt;
578 is_wait = _is_wait;
579 called_by_wait = _called_by_wait;
580 bits = _bits;
581 }
582
583 ~TraceSuspendDebugBits() {
584 if (!is_wait) {
585 #if 1
586 // By default, don't trace bits for is_ext_suspend_completed() calls.
587 // That trace is very chatty.
588 return;
589 #else
590 if (!called_by_wait) {
591 // If tracing for is_ext_suspend_completed() is enabled, then only
592 // trace calls to it from wait_for_ext_suspend_completion()
593 return;
594 }
595 #endif
596 }
597
598 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
599 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
600 MutexLocker ml(Threads_lock); // needed for get_thread_name()
601 ResourceMark rm;
602
603 tty->print_cr(
604 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
605 jt->get_thread_name(), *bits);
606
607 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
608 }
609 }
610 }
611 };
612 #undef DEBUG_FALSE_BITS
613
614
615 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
616 uint32_t *bits) {
617 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
618
619 bool did_trans_retry = false; // only do thread_in_native_trans retry once
620 bool do_trans_retry; // flag to force the retry
621
622 *bits |= 0x00000001;
623
624 do {
625 do_trans_retry = false;
626
627 if (is_exiting()) {
628 // Thread is in the process of exiting. This is always checked
629 // first to reduce the risk of dereferencing a freed JavaThread.
630 *bits |= 0x00000100;
631 return false;
632 }
633
634 if (!is_external_suspend()) {
635 // Suspend request is cancelled. This is always checked before
636 // is_ext_suspended() to reduce the risk of a rogue resume
637 // confusing the thread that made the suspend request.
638 *bits |= 0x00000200;
639 return false;
640 }
641
642 if (is_ext_suspended()) {
643 // thread is suspended
644 *bits |= 0x00000400;
645 return true;
646 }
647
648 // Now that we no longer do hard suspends of threads running
649 // native code, the target thread can be changing thread state
650 // while we are in this routine:
651 //
652 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
653 //
654 // We save a copy of the thread state as observed at this moment
655 // and make our decision about suspend completeness based on the
656 // copy. This closes the race where the thread state is seen as
657 // _thread_in_native_trans in the if-thread_blocked check, but is
658 // seen as _thread_blocked in if-thread_in_native_trans check.
659 JavaThreadState save_state = thread_state();
660
661 if (save_state == _thread_blocked && is_suspend_equivalent()) {
662 // If the thread's state is _thread_blocked and this blocking
663 // condition is known to be equivalent to a suspend, then we can
664 // consider the thread to be externally suspended. This means that
665 // the code that sets _thread_blocked has been modified to do
666 // self-suspension if the blocking condition releases. We also
667 // used to check for CONDVAR_WAIT here, but that is now covered by
668 // the _thread_blocked with self-suspension check.
669 //
670 // Return true since we wouldn't be here unless there was still an
671 // external suspend request.
672 *bits |= 0x00001000;
673 return true;
674 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
675 // Threads running native code will self-suspend on native==>VM/Java
676 // transitions. If its stack is walkable (should always be the case
677 // unless this function is called before the actual java_suspend()
678 // call), then the wait is done.
679 *bits |= 0x00002000;
680 return true;
681 } else if (!called_by_wait && !did_trans_retry &&
682 save_state == _thread_in_native_trans &&
683 frame_anchor()->walkable()) {
684 // The thread is transitioning from thread_in_native to another
685 // thread state. check_safepoint_and_suspend_for_native_trans()
686 // will force the thread to self-suspend. If it hasn't gotten
687 // there yet we may have caught the thread in-between the native
688 // code check above and the self-suspend. Lucky us. If we were
689 // called by wait_for_ext_suspend_completion(), then it
690 // will be doing the retries so we don't have to.
691 //
692 // Since we use the saved thread state in the if-statement above,
693 // there is a chance that the thread has already transitioned to
694 // _thread_blocked by the time we get here. In that case, we will
695 // make a single unnecessary pass through the logic below. This
696 // doesn't hurt anything since we still do the trans retry.
697
698 *bits |= 0x00004000;
699
700 // Once the thread leaves thread_in_native_trans for another
701 // thread state, we break out of this retry loop. We shouldn't
702 // need this flag to prevent us from getting back here, but
703 // sometimes paranoia is good.
704 did_trans_retry = true;
705
706 // We wait for the thread to transition to a more usable state.
707 for (int i = 1; i <= SuspendRetryCount; i++) {
708 // We used to do an "os::yield_all(i)" call here with the intention
709 // that yielding would increase on each retry. However, the parameter
710 // is ignored on Linux which means the yield didn't scale up. Waiting
711 // on the SR_lock below provides a much more predictable scale up for
712 // the delay. It also provides a simple/direct point to check for any
713 // safepoint requests from the VMThread
714
715 // temporarily drops SR_lock while doing wait with safepoint check
716 // (if we're a JavaThread - the WatcherThread can also call this)
717 // and increase delay with each retry
718 if (Thread::current()->is_Java_thread()) {
719 SR_lock()->wait(i * delay);
720 } else {
721 SR_lock()->wait_without_safepoint_check(i * delay);
722 }
723
724 // check the actual thread state instead of what we saved above
725 if (thread_state() != _thread_in_native_trans) {
726 // the thread has transitioned to another thread state so
727 // try all the checks (except this one) one more time.
728 do_trans_retry = true;
729 break;
730 }
731 } // end retry loop
732
733
734 }
735 } while (do_trans_retry);
736
737 *bits |= 0x00000010;
738 return false;
739 }
740
741 // Wait for an external suspend request to complete (or be cancelled).
742 // Returns true if the thread is externally suspended and false otherwise.
743 //
744 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
745 uint32_t *bits) {
746 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
747 false /* !called_by_wait */, bits);
748
749 // local flag copies to minimize SR_lock hold time
750 bool is_suspended;
751 bool pending;
752 uint32_t reset_bits;
753
754 // set a marker so is_ext_suspend_completed() knows we are the caller
755 *bits |= 0x00010000;
756
757 // We use reset_bits to reinitialize the bits value at the top of
758 // each retry loop. This allows the caller to make use of any
759 // unused bits for their own marking purposes.
760 reset_bits = *bits;
761
762 {
763 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
764 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
765 delay, bits);
766 pending = is_external_suspend();
767 }
768 // must release SR_lock to allow suspension to complete
769
770 if (!pending) {
771 // A cancelled suspend request is the only false return from
772 // is_ext_suspend_completed() that keeps us from entering the
773 // retry loop.
774 *bits |= 0x00020000;
775 return false;
776 }
777
778 if (is_suspended) {
779 *bits |= 0x00040000;
780 return true;
781 }
782
783 for (int i = 1; i <= retries; i++) {
784 *bits = reset_bits; // reinit to only track last retry
785
786 // We used to do an "os::yield_all(i)" call here with the intention
787 // that yielding would increase on each retry. However, the parameter
788 // is ignored on Linux which means the yield didn't scale up. Waiting
789 // on the SR_lock below provides a much more predictable scale up for
790 // the delay. It also provides a simple/direct point to check for any
791 // safepoint requests from the VMThread
792
793 {
794 Thread* t = Thread::current();
795 MonitorLocker ml(SR_lock(),
796 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
797 // wait with safepoint check (if we're a JavaThread - the WatcherThread
798 // can also call this) and increase delay with each retry
799 ml.wait(i * delay);
800
801 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
802 delay, bits);
803
804 // It is possible for the external suspend request to be cancelled
805 // (by a resume) before the actual suspend operation is completed.
806 // Refresh our local copy to see if we still need to wait.
807 pending = is_external_suspend();
808 }
809
810 if (!pending) {
811 // A cancelled suspend request is the only false return from
812 // is_ext_suspend_completed() that keeps us from staying in the
813 // retry loop.
814 *bits |= 0x00080000;
815 return false;
816 }
817
818 if (is_suspended) {
819 *bits |= 0x00100000;
820 return true;
821 }
822 } // end retry loop
823
824 // thread did not suspend after all our retries
825 *bits |= 0x00200000;
826 return false;
827 }
828
829 // Called from API entry points which perform stack walking. If the
830 // associated JavaThread is the current thread, then wait_for_suspend
831 // is not used. Otherwise, it determines if we should wait for the
832 // "other" thread to complete external suspension. (NOTE: in future
833 // releases the suspension mechanism should be reimplemented so this
834 // is not necessary.)
835 //
836 bool
837 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
838 if (this != JavaThread::current()) {
839 // "other" threads require special handling.
840 if (wait_for_suspend) {
841 // We are allowed to wait for the external suspend to complete
842 // so give the other thread a chance to get suspended.
843 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
844 SuspendRetryDelay, bits)) {
845 // Didn't make it so let the caller know.
846 return false;
847 }
848 }
849 // We aren't allowed to wait for the external suspend to complete
850 // so if the other thread isn't externally suspended we need to
851 // let the caller know.
852 else if (!is_ext_suspend_completed_with_lock(bits)) {
853 return false;
854 }
855 }
856
857 return true;
858 }
859
860 // GC Support
861 bool Thread::claim_par_threads_do(uintx claim_token) {
862 uintx token = _threads_do_token;
863 if (token != claim_token) {
864 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
865 if (res == token) {
866 return true;
867 }
868 guarantee(res == claim_token, "invariant");
869 }
870 return false;
871 }
872
873 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
874 active_handles()->oops_do(f);
875 // Do oop for ThreadShadow
876 f->do_oop((oop*)&_pending_exception);
877 handle_area()->oops_do(f);
878
879 // We scan thread local monitor lists here, and the remaining global
880 // monitors in ObjectSynchronizer::oops_do().
881 ObjectSynchronizer::thread_local_used_oops_do(this, f);
882 }
883
884 void Thread::metadata_handles_do(void f(Metadata*)) {
885 // Only walk the Handles in Thread.
886 if (metadata_handles() != NULL) {
887 for (int i = 0; i< metadata_handles()->length(); i++) {
888 f(metadata_handles()->at(i));
889 }
890 }
891 }
892
893 void Thread::print_on(outputStream* st, bool print_extended_info) const {
894 // get_priority assumes osthread initialized
895 if (osthread() != NULL) {
896 int os_prio;
897 if (os::get_native_priority(this, &os_prio) == OS_OK) {
898 st->print("os_prio=%d ", os_prio);
899 }
900
901 st->print("cpu=%.2fms ",
902 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
903 );
904 st->print("elapsed=%.2fs ",
905 _statistical_info.getElapsedTime() / 1000.0
906 );
907 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
908 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
909 st->print("allocated=" SIZE_FORMAT "%s ",
910 byte_size_in_proper_unit(allocated_bytes),
911 proper_unit_for_byte_size(allocated_bytes)
912 );
913 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
914 }
915
916 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
917 osthread()->print_on(st);
918 }
919 ThreadsSMRSupport::print_info_on(this, st);
920 st->print(" ");
921 debug_only(if (WizardMode) print_owned_locks_on(st);)
922 }
923
924 void Thread::print() const { print_on(tty); }
925
926 // Thread::print_on_error() is called by fatal error handler. Don't use
927 // any lock or allocate memory.
928 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
929 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
930
931 if (is_VM_thread()) { st->print("VMThread"); }
932 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
933 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
934 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
935 else { st->print("Thread"); }
936
937 if (is_Named_thread()) {
938 st->print(" \"%s\"", name());
939 }
940
941 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
942 p2i(stack_end()), p2i(stack_base()));
943
944 if (osthread()) {
945 st->print(" [id=%d]", osthread()->thread_id());
946 }
947
948 ThreadsSMRSupport::print_info_on(this, st);
949 }
950
951 void Thread::print_value_on(outputStream* st) const {
952 if (is_Named_thread()) {
953 st->print(" \"%s\" ", name());
954 }
955 st->print(INTPTR_FORMAT, p2i(this)); // print address
956 }
957
958 #ifdef ASSERT
959 void Thread::print_owned_locks_on(outputStream* st) const {
960 Mutex* cur = _owned_locks;
961 if (cur == NULL) {
962 st->print(" (no locks) ");
963 } else {
964 st->print_cr(" Locks owned:");
965 while (cur) {
966 cur->print_on(st);
967 cur = cur->next();
968 }
969 }
970 }
971
972 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
973 void Thread::check_possible_safepoint() {
974 if (!is_Java_thread()) return;
975
976 if (_no_safepoint_count > 0) {
977 print_owned_locks();
978 fatal("Possible safepoint reached by thread that does not allow it");
979 }
980 #ifdef CHECK_UNHANDLED_OOPS
981 // Clear unhandled oops in JavaThreads so we get a crash right away.
982 clear_unhandled_oops();
983 #endif // CHECK_UNHANDLED_OOPS
984 }
985
986 void Thread::check_for_valid_safepoint_state() {
987 if (!is_Java_thread()) return;
988
989 // Check NoSafepointVerifier, which is implied by locks taken that can be
990 // shared with the VM thread. This makes sure that no locks with allow_vm_block
991 // are held.
992 check_possible_safepoint();
993
994 if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
995 fatal("LEAF method calling lock?");
996 }
997
998 if (GCALotAtAllSafepoints) {
999 // We could enter a safepoint here and thus have a gc
1000 InterfaceSupport::check_gc_alot();
1001 }
1002 }
1003 #endif // ASSERT
1004
1005 bool Thread::is_in_stack(address adr) const {
1006 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1007 address end = os::current_stack_pointer();
1008 // Allow non Java threads to call this without stack_base
1009 if (_stack_base == NULL) return true;
1010 if (stack_base() >= adr && adr >= end) return true;
1011
1012 return false;
1013 }
1014
1015 bool Thread::is_in_usable_stack(address adr) const {
1016 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1017 size_t usable_stack_size = _stack_size - stack_guard_size;
1018
1019 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1020 }
1021
1022
1023 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1024 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1025 // used for compilation in the future. If that change is made, the need for these methods
1026 // should be revisited, and they should be removed if possible.
1027
1028 bool Thread::is_lock_owned(address adr) const {
1029 return on_local_stack(adr);
1030 }
1031
1032 bool Thread::set_as_starting_thread() {
1033 assert(_starting_thread == NULL, "already initialized: "
1034 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1035 // NOTE: this must be called inside the main thread.
1036 DEBUG_ONLY(_starting_thread = this;)
1037 return os::create_main_thread((JavaThread*)this);
1038 }
1039
1040 static void initialize_class(Symbol* class_name, TRAPS) {
1041 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1042 InstanceKlass::cast(klass)->initialize(CHECK);
1043 }
1044
1045
1046 // Creates the initial ThreadGroup
1047 static Handle create_initial_thread_group(TRAPS) {
1048 Handle system_instance = JavaCalls::construct_new_instance(
1049 SystemDictionary::ThreadGroup_klass(),
1050 vmSymbols::void_method_signature(),
1051 CHECK_NH);
1052 Universe::set_system_thread_group(system_instance());
1053
1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055 Handle main_instance = JavaCalls::construct_new_instance(
1056 SystemDictionary::ThreadGroup_klass(),
1057 vmSymbols::threadgroup_string_void_signature(),
1058 system_instance,
1059 string,
1060 CHECK_NH);
1061 return main_instance;
1062 }
1063
1064 // Creates the initial Thread
1065 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1066 TRAPS) {
1067 InstanceKlass* ik = SystemDictionary::Thread_klass();
1068 assert(ik->is_initialized(), "must be");
1069 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1070
1071 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1072 // constructor calls Thread.current(), which must be set here for the
1073 // initial thread.
1074 java_lang_Thread::set_thread(thread_oop(), thread);
1075 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076 thread->set_threadObj(thread_oop());
1077
1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079
1080 JavaValue result(T_VOID);
1081 JavaCalls::call_special(&result, thread_oop,
1082 ik,
1083 vmSymbols::object_initializer_name(),
1084 vmSymbols::threadgroup_string_void_signature(),
1085 thread_group,
1086 string,
1087 CHECK_NULL);
1088 return thread_oop();
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098 fieldDescriptor fd;
1099 bool found = k != NULL &&
1100 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101 vmSymbols::string_signature(), &fd);
1102 if (found) {
1103 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104 if (name_oop == NULL) {
1105 return NULL;
1106 }
1107 const char* name = java_lang_String::as_utf8_string(name_oop,
1108 java_runtime_name,
1109 sizeof(java_runtime_name));
1110 return name;
1111 } else {
1112 return NULL;
1113 }
1114 }
1115
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120 fieldDescriptor fd;
1121 bool found = k != NULL &&
1122 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123 vmSymbols::string_signature(), &fd);
1124 if (found) {
1125 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126 if (name_oop == NULL) {
1127 return NULL;
1128 }
1129 const char* name = java_lang_String::as_utf8_string(name_oop,
1130 java_runtime_version,
1131 sizeof(java_runtime_version));
1132 return name;
1133 } else {
1134 return NULL;
1135 }
1136 }
1137
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142 if (klass != NULL) {
1143 JavaValue result(T_VOID);
1144 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145 vmSymbols::void_method_signature(),
1146 CHECK);
1147 }
1148 }
1149
1150 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1151 bool daemon, TRAPS) {
1152 assert(thread_group.not_null(), "thread group should be specified");
1153 assert(threadObj() == NULL, "should only create Java thread object once");
1154
1155 InstanceKlass* ik = SystemDictionary::Thread_klass();
1156 assert(ik->is_initialized(), "must be");
1157 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1158
1159 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1160 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1161 // constructor calls Thread.current(), which must be set here.
1162 java_lang_Thread::set_thread(thread_oop(), this);
1163 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1164 set_threadObj(thread_oop());
1165
1166 JavaValue result(T_VOID);
1167 if (thread_name != NULL) {
1168 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1169 // Thread gets assigned specified name and null target
1170 JavaCalls::call_special(&result,
1171 thread_oop,
1172 ik,
1173 vmSymbols::object_initializer_name(),
1174 vmSymbols::threadgroup_string_void_signature(),
1175 thread_group,
1176 name,
1177 THREAD);
1178 } else {
1179 // Thread gets assigned name "Thread-nnn" and null target
1180 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1181 JavaCalls::call_special(&result,
1182 thread_oop,
1183 ik,
1184 vmSymbols::object_initializer_name(),
1185 vmSymbols::threadgroup_runnable_void_signature(),
1186 thread_group,
1187 Handle(),
1188 THREAD);
1189 }
1190
1191
1192 if (daemon) {
1193 java_lang_Thread::set_daemon(thread_oop());
1194 }
1195
1196 if (HAS_PENDING_EXCEPTION) {
1197 return;
1198 }
1199
1200 Klass* group = SystemDictionary::ThreadGroup_klass();
1201 Handle threadObj(THREAD, this->threadObj());
1202
1203 JavaCalls::call_special(&result,
1204 thread_group,
1205 group,
1206 vmSymbols::add_method_name(),
1207 vmSymbols::thread_void_signature(),
1208 threadObj, // Arg 1
1209 THREAD);
1210 }
1211
1212 // List of all NonJavaThreads and safe iteration over that list.
1213
1214 class NonJavaThread::List {
1215 public:
1216 NonJavaThread* volatile _head;
1217 SingleWriterSynchronizer _protect;
1218
1219 List() : _head(NULL), _protect() {}
1220 };
1221
1222 NonJavaThread::List NonJavaThread::_the_list;
1223
1224 NonJavaThread::Iterator::Iterator() :
1225 _protect_enter(_the_list._protect.enter()),
1226 _current(OrderAccess::load_acquire(&_the_list._head))
1227 {}
1228
1229 NonJavaThread::Iterator::~Iterator() {
1230 _the_list._protect.exit(_protect_enter);
1231 }
1232
1233 void NonJavaThread::Iterator::step() {
1234 assert(!end(), "precondition");
1235 _current = OrderAccess::load_acquire(&_current->_next);
1236 }
1237
1238 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1239 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1240 }
1241
1242 NonJavaThread::~NonJavaThread() { }
1243
1244 void NonJavaThread::add_to_the_list() {
1245 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1246 // Initialize BarrierSet-related data before adding to list.
1247 BarrierSet::barrier_set()->on_thread_attach(this);
1248 OrderAccess::release_store(&_next, _the_list._head);
1249 OrderAccess::release_store(&_the_list._head, this);
1250 }
1251
1252 void NonJavaThread::remove_from_the_list() {
1253 {
1254 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1255 // Cleanup BarrierSet-related data before removing from list.
1256 BarrierSet::barrier_set()->on_thread_detach(this);
1257 NonJavaThread* volatile* p = &_the_list._head;
1258 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1259 if (t == this) {
1260 *p = _next;
1261 break;
1262 }
1263 }
1264 }
1265 // Wait for any in-progress iterators. Concurrent synchronize is not
1266 // allowed, so do it while holding a dedicated lock. Outside and distinct
1267 // from NJTList_lock in case an iteration attempts to lock it.
1268 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1269 _the_list._protect.synchronize();
1270 _next = NULL; // Safe to drop the link now.
1271 }
1272
1273 void NonJavaThread::pre_run() {
1274 add_to_the_list();
1275
1276 // This is slightly odd in that NamedThread is a subclass, but
1277 // in fact name() is defined in Thread
1278 assert(this->name() != NULL, "thread name was not set before it was started");
1279 this->set_native_thread_name(this->name());
1280 }
1281
1282 void NonJavaThread::post_run() {
1283 JFR_ONLY(Jfr::on_thread_exit(this);)
1284 remove_from_the_list();
1285 // Ensure thread-local-storage is cleared before termination.
1286 Thread::clear_thread_current();
1287 }
1288
1289 // NamedThread -- non-JavaThread subclasses with multiple
1290 // uniquely named instances should derive from this.
1291 NamedThread::NamedThread() :
1292 NonJavaThread(),
1293 _name(NULL),
1294 _processed_thread(NULL),
1295 _gc_id(GCId::undefined())
1296 {}
1297
1298 NamedThread::~NamedThread() {
1299 FREE_C_HEAP_ARRAY(char, _name);
1300 }
1301
1302 void NamedThread::set_name(const char* format, ...) {
1303 guarantee(_name == NULL, "Only get to set name once.");
1304 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1305 va_list ap;
1306 va_start(ap, format);
1307 jio_vsnprintf(_name, max_name_len, format, ap);
1308 va_end(ap);
1309 }
1310
1311 void NamedThread::print_on(outputStream* st) const {
1312 st->print("\"%s\" ", name());
1313 Thread::print_on(st);
1314 st->cr();
1315 }
1316
1317
1318 // ======= WatcherThread ========
1319
1320 // The watcher thread exists to simulate timer interrupts. It should
1321 // be replaced by an abstraction over whatever native support for
1322 // timer interrupts exists on the platform.
1323
1324 WatcherThread* WatcherThread::_watcher_thread = NULL;
1325 bool WatcherThread::_startable = false;
1326 volatile bool WatcherThread::_should_terminate = false;
1327
1328 WatcherThread::WatcherThread() : NonJavaThread() {
1329 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1330 if (os::create_thread(this, os::watcher_thread)) {
1331 _watcher_thread = this;
1332
1333 // Set the watcher thread to the highest OS priority which should not be
1334 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1335 // is created. The only normal thread using this priority is the reference
1336 // handler thread, which runs for very short intervals only.
1337 // If the VMThread's priority is not lower than the WatcherThread profiling
1338 // will be inaccurate.
1339 os::set_priority(this, MaxPriority);
1340 if (!DisableStartThread) {
1341 os::start_thread(this);
1342 }
1343 }
1344 }
1345
1346 int WatcherThread::sleep() const {
1347 // The WatcherThread does not participate in the safepoint protocol
1348 // for the PeriodicTask_lock because it is not a JavaThread.
1349 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1350
1351 if (_should_terminate) {
1352 // check for termination before we do any housekeeping or wait
1353 return 0; // we did not sleep.
1354 }
1355
1356 // remaining will be zero if there are no tasks,
1357 // causing the WatcherThread to sleep until a task is
1358 // enrolled
1359 int remaining = PeriodicTask::time_to_wait();
1360 int time_slept = 0;
1361
1362 // we expect this to timeout - we only ever get unparked when
1363 // we should terminate or when a new task has been enrolled
1364 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1365
1366 jlong time_before_loop = os::javaTimeNanos();
1367
1368 while (true) {
1369 bool timedout = ml.wait(remaining);
1370 jlong now = os::javaTimeNanos();
1371
1372 if (remaining == 0) {
1373 // if we didn't have any tasks we could have waited for a long time
1374 // consider the time_slept zero and reset time_before_loop
1375 time_slept = 0;
1376 time_before_loop = now;
1377 } else {
1378 // need to recalculate since we might have new tasks in _tasks
1379 time_slept = (int) ((now - time_before_loop) / 1000000);
1380 }
1381
1382 // Change to task list or spurious wakeup of some kind
1383 if (timedout || _should_terminate) {
1384 break;
1385 }
1386
1387 remaining = PeriodicTask::time_to_wait();
1388 if (remaining == 0) {
1389 // Last task was just disenrolled so loop around and wait until
1390 // another task gets enrolled
1391 continue;
1392 }
1393
1394 remaining -= time_slept;
1395 if (remaining <= 0) {
1396 break;
1397 }
1398 }
1399
1400 return time_slept;
1401 }
1402
1403 void WatcherThread::run() {
1404 assert(this == watcher_thread(), "just checking");
1405
1406 this->set_active_handles(JNIHandleBlock::allocate_block());
1407 while (true) {
1408 assert(watcher_thread() == Thread::current(), "thread consistency check");
1409 assert(watcher_thread() == this, "thread consistency check");
1410
1411 // Calculate how long it'll be until the next PeriodicTask work
1412 // should be done, and sleep that amount of time.
1413 int time_waited = sleep();
1414
1415 if (VMError::is_error_reported()) {
1416 // A fatal error has happened, the error handler(VMError::report_and_die)
1417 // should abort JVM after creating an error log file. However in some
1418 // rare cases, the error handler itself might deadlock. Here periodically
1419 // check for error reporting timeouts, and if it happens, just proceed to
1420 // abort the VM.
1421
1422 // This code is in WatcherThread because WatcherThread wakes up
1423 // periodically so the fatal error handler doesn't need to do anything;
1424 // also because the WatcherThread is less likely to crash than other
1425 // threads.
1426
1427 for (;;) {
1428 // Note: we use naked sleep in this loop because we want to avoid using
1429 // any kind of VM infrastructure which may be broken at this point.
1430 if (VMError::check_timeout()) {
1431 // We hit error reporting timeout. Error reporting was interrupted and
1432 // will be wrapping things up now (closing files etc). Give it some more
1433 // time, then quit the VM.
1434 os::naked_short_sleep(200);
1435 // Print a message to stderr.
1436 fdStream err(defaultStream::output_fd());
1437 err.print_raw_cr("# [ timer expired, abort... ]");
1438 // skip atexit/vm_exit/vm_abort hooks
1439 os::die();
1440 }
1441
1442 // Wait a second, then recheck for timeout.
1443 os::naked_short_sleep(999);
1444 }
1445 }
1446
1447 if (_should_terminate) {
1448 // check for termination before posting the next tick
1449 break;
1450 }
1451
1452 PeriodicTask::real_time_tick(time_waited);
1453 }
1454
1455 // Signal that it is terminated
1456 {
1457 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1458 _watcher_thread = NULL;
1459 Terminator_lock->notify_all();
1460 }
1461 }
1462
1463 void WatcherThread::start() {
1464 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1465
1466 if (watcher_thread() == NULL && _startable) {
1467 _should_terminate = false;
1468 // Create the single instance of WatcherThread
1469 new WatcherThread();
1470 }
1471 }
1472
1473 void WatcherThread::make_startable() {
1474 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1475 _startable = true;
1476 }
1477
1478 void WatcherThread::stop() {
1479 {
1480 // Follow normal safepoint aware lock enter protocol since the
1481 // WatcherThread is stopped by another JavaThread.
1482 MutexLocker ml(PeriodicTask_lock);
1483 _should_terminate = true;
1484
1485 WatcherThread* watcher = watcher_thread();
1486 if (watcher != NULL) {
1487 // unpark the WatcherThread so it can see that it should terminate
1488 watcher->unpark();
1489 }
1490 }
1491
1492 MonitorLocker mu(Terminator_lock);
1493
1494 while (watcher_thread() != NULL) {
1495 // This wait should make safepoint checks, wait without a timeout,
1496 // and wait as a suspend-equivalent condition.
1497 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1498 }
1499 }
1500
1501 void WatcherThread::unpark() {
1502 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1503 PeriodicTask_lock->notify();
1504 }
1505
1506 void WatcherThread::print_on(outputStream* st) const {
1507 st->print("\"%s\" ", name());
1508 Thread::print_on(st);
1509 st->cr();
1510 }
1511
1512 // ======= JavaThread ========
1513
1514 #if INCLUDE_JVMCI
1515
1516 jlong* JavaThread::_jvmci_old_thread_counters;
1517
1518 bool jvmci_counters_include(JavaThread* thread) {
1519 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1520 }
1521
1522 void JavaThread::collect_counters(jlong* array, int length) {
1523 assert(length == JVMCICounterSize, "wrong value");
1524 for (int i = 0; i < length; i++) {
1525 array[i] = _jvmci_old_thread_counters[i];
1526 }
1527 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1528 if (jvmci_counters_include(tp)) {
1529 for (int i = 0; i < length; i++) {
1530 array[i] += tp->_jvmci_counters[i];
1531 }
1532 }
1533 }
1534 }
1535
1536 // Attempt to enlarge the array for per thread counters.
1537 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1538 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1539 if (old_counters == NULL) {
1540 old_counters = new_counters;
1541 memset(old_counters, 0, sizeof(jlong) * new_size);
1542 } else {
1543 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1544 new_counters[i] = old_counters[i];
1545 }
1546 if (new_size > current_size) {
1547 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1548 }
1549 FREE_C_HEAP_ARRAY(jlong, old_counters);
1550 }
1551 return new_counters;
1552 }
1553
1554 // Attempt to enlarge the array for per thread counters.
1555 void JavaThread::resize_counters(int current_size, int new_size) {
1556 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1557 }
1558
1559 class VM_JVMCIResizeCounters : public VM_Operation {
1560 private:
1561 int _new_size;
1562
1563 public:
1564 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { }
1565 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1566 bool allow_nested_vm_operations() const { return true; }
1567 void doit() {
1568 // Resize the old thread counters array
1569 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1570 JavaThread::_jvmci_old_thread_counters = new_counters;
1571
1572 // Now resize each threads array
1573 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1574 tp->resize_counters(JVMCICounterSize, _new_size);
1575 }
1576 JVMCICounterSize = _new_size;
1577 }
1578 };
1579
1580 void JavaThread::resize_all_jvmci_counters(int new_size) {
1581 VM_JVMCIResizeCounters op(new_size);
1582 VMThread::execute(&op);
1583 }
1584
1585 #endif // INCLUDE_JVMCI
1586
1587 // A JavaThread is a normal Java thread
1588
1589 void JavaThread::initialize() {
1590 // Initialize fields
1591
1592 set_saved_exception_pc(NULL);
1593 set_threadObj(NULL);
1594 _anchor.clear();
1595 set_entry_point(NULL);
1596 set_jni_functions(jni_functions());
1597 set_callee_target(NULL);
1598 set_vm_result(NULL);
1599 set_vm_result_2(NULL);
1600 set_vframe_array_head(NULL);
1601 set_vframe_array_last(NULL);
1602 set_deferred_locals(NULL);
1603 set_deopt_mark(NULL);
1604 set_deopt_compiled_method(NULL);
1605 set_monitor_chunks(NULL);
1606 _on_thread_list = false;
1607 set_thread_state(_thread_new);
1608 _terminated = _not_terminated;
1609 _array_for_gc = NULL;
1610 _suspend_equivalent = false;
1611 _in_deopt_handler = 0;
1612 _doing_unsafe_access = false;
1613 _stack_guard_state = stack_guard_unused;
1614 #if INCLUDE_JVMCI
1615 _pending_monitorenter = false;
1616 _pending_deoptimization = -1;
1617 _pending_failed_speculation = 0;
1618 _pending_transfer_to_interpreter = false;
1619 _in_retryable_allocation = false;
1620 _jvmci._alternate_call_target = NULL;
1621 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1622 _jvmci_counters = NULL;
1623 if (JVMCICounterSize > 0) {
1624 resize_counters(0, (int) JVMCICounterSize);
1625 }
1626 #endif // INCLUDE_JVMCI
1627 _reserved_stack_activation = NULL; // stack base not known yet
1628 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1629 _exception_pc = 0;
1630 _exception_handler_pc = 0;
1631 _is_method_handle_return = 0;
1632 _jvmti_thread_state= NULL;
1633 _should_post_on_exceptions_flag = JNI_FALSE;
1634 _interp_only_mode = 0;
1635 _special_runtime_exit_condition = _no_async_condition;
1636 _pending_async_exception = NULL;
1637 _thread_stat = NULL;
1638 _thread_stat = new ThreadStatistics();
1639 _jni_active_critical = 0;
1640 _pending_jni_exception_check_fn = NULL;
1641 _do_not_unlock_if_synchronized = false;
1642 _cached_monitor_info = NULL;
1643 _parker = Parker::Allocate(this);
1644 _SleepEvent = ParkEvent::Allocate(this);
1645 // Setup safepoint state info for this thread
1646 ThreadSafepointState::create(this);
1647
1648 debug_only(_java_call_counter = 0);
1649
1650 // JVMTI PopFrame support
1651 _popframe_condition = popframe_inactive;
1652 _popframe_preserved_args = NULL;
1653 _popframe_preserved_args_size = 0;
1654 _frames_to_pop_failed_realloc = 0;
1655
1656 if (SafepointMechanism::uses_thread_local_poll()) {
1657 SafepointMechanism::initialize_header(this);
1658 }
1659
1660 _class_to_be_initialized = NULL;
1661
1662 pd_initialize();
1663 }
1664
1665 JavaThread::JavaThread(bool is_attaching_via_jni) :
1666 Thread() {
1667 initialize();
1668 if (is_attaching_via_jni) {
1669 _jni_attach_state = _attaching_via_jni;
1670 } else {
1671 _jni_attach_state = _not_attaching_via_jni;
1672 }
1673 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1674 }
1675
1676
1677 // interrupt support
1678
1679 void JavaThread::interrupt() {
1680 debug_only(check_for_dangling_thread_pointer(this);)
1681
1682 // For Windows _interrupt_event
1683 osthread()->set_interrupted(true);
1684
1685 // For Thread.sleep
1686 _SleepEvent->unpark();
1687
1688 // For JSR166 LockSupport.park
1689 parker()->unpark();
1690
1691 // For ObjectMonitor and JvmtiRawMonitor
1692 _ParkEvent->unpark();
1693 }
1694
1695
1696 bool JavaThread::is_interrupted(bool clear_interrupted) {
1697 debug_only(check_for_dangling_thread_pointer(this);)
1698 bool interrupted = java_lang_Thread::interrupted(threadObj());
1699
1700 // NOTE that since there is no "lock" around the interrupt and
1701 // is_interrupted operations, there is the possibility that the
1702 // interrupted flag will be "false" but that the
1703 // low-level events will be in the signaled state. This is
1704 // intentional. The effect of this is that Object.wait() and
1705 // LockSupport.park() will appear to have a spurious wakeup, which
1706 // is allowed and not harmful, and the possibility is so rare that
1707 // it is not worth the added complexity to add yet another lock.
1708 // For the sleep event an explicit reset is performed on entry
1709 // to JavaThread::sleep, so there is no early return. It has also been
1710 // recommended not to put the interrupted flag into the "event"
1711 // structure because it hides the issue.
1712 // Also, because there is no lock, we must only clear the interrupt
1713 // state if we are going to report that we were interrupted; otherwise
1714 // an interrupt that happens just after we read the field would be lost.
1715 if (interrupted && clear_interrupted) {
1716 java_lang_Thread::set_interrupted(threadObj(), false);
1717 osthread()->set_interrupted(false);
1718 }
1719
1720 return interrupted;
1721 }
1722
1723 bool JavaThread::reguard_stack(address cur_sp) {
1724 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1725 && _stack_guard_state != stack_guard_reserved_disabled) {
1726 return true; // Stack already guarded or guard pages not needed.
1727 }
1728
1729 if (register_stack_overflow()) {
1730 // For those architectures which have separate register and
1731 // memory stacks, we must check the register stack to see if
1732 // it has overflowed.
1733 return false;
1734 }
1735
1736 // Java code never executes within the yellow zone: the latter is only
1737 // there to provoke an exception during stack banging. If java code
1738 // is executing there, either StackShadowPages should be larger, or
1739 // some exception code in c1, c2 or the interpreter isn't unwinding
1740 // when it should.
1741 guarantee(cur_sp > stack_reserved_zone_base(),
1742 "not enough space to reguard - increase StackShadowPages");
1743 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1744 enable_stack_yellow_reserved_zone();
1745 if (reserved_stack_activation() != stack_base()) {
1746 set_reserved_stack_activation(stack_base());
1747 }
1748 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1749 set_reserved_stack_activation(stack_base());
1750 enable_stack_reserved_zone();
1751 }
1752 return true;
1753 }
1754
1755 bool JavaThread::reguard_stack(void) {
1756 return reguard_stack(os::current_stack_pointer());
1757 }
1758
1759
1760 void JavaThread::block_if_vm_exited() {
1761 if (_terminated == _vm_exited) {
1762 // _vm_exited is set at safepoint, and Threads_lock is never released
1763 // we will block here forever.
1764 // Here we can be doing a jump from a safe state to an unsafe state without
1765 // proper transition, but it happens after the final safepoint has begun.
1766 set_thread_state(_thread_in_vm);
1767 Threads_lock->lock();
1768 ShouldNotReachHere();
1769 }
1770 }
1771
1772
1773 // Remove this ifdef when C1 is ported to the compiler interface.
1774 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1775 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1776
1777 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1778 Thread() {
1779 initialize();
1780 _jni_attach_state = _not_attaching_via_jni;
1781 set_entry_point(entry_point);
1782 // Create the native thread itself.
1783 // %note runtime_23
1784 os::ThreadType thr_type = os::java_thread;
1785 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1786 os::java_thread;
1787 os::create_thread(this, thr_type, stack_sz);
1788 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1789 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1790 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1791 // the exception consists of creating the exception object & initializing it, initialization
1792 // will leave the VM via a JavaCall and then all locks must be unlocked).
1793 //
1794 // The thread is still suspended when we reach here. Thread must be explicit started
1795 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1796 // by calling Threads:add. The reason why this is not done here, is because the thread
1797 // object must be fully initialized (take a look at JVM_Start)
1798 }
1799
1800 JavaThread::~JavaThread() {
1801
1802 // JSR166 -- return the parker to the free list
1803 Parker::Release(_parker);
1804 _parker = NULL;
1805
1806 // Return the sleep event to the free list
1807 ParkEvent::Release(_SleepEvent);
1808 _SleepEvent = NULL;
1809
1810 // Free any remaining previous UnrollBlock
1811 vframeArray* old_array = vframe_array_last();
1812
1813 if (old_array != NULL) {
1814 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1815 old_array->set_unroll_block(NULL);
1816 delete old_info;
1817 delete old_array;
1818 }
1819
1820 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1821 if (deferred != NULL) {
1822 // This can only happen if thread is destroyed before deoptimization occurs.
1823 assert(deferred->length() != 0, "empty array!");
1824 do {
1825 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1826 deferred->remove_at(0);
1827 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1828 delete dlv;
1829 } while (deferred->length() != 0);
1830 delete deferred;
1831 }
1832
1833 // All Java related clean up happens in exit
1834 ThreadSafepointState::destroy(this);
1835 if (_thread_stat != NULL) delete _thread_stat;
1836
1837 #if INCLUDE_JVMCI
1838 if (JVMCICounterSize > 0) {
1839 if (jvmci_counters_include(this)) {
1840 for (int i = 0; i < JVMCICounterSize; i++) {
1841 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1842 }
1843 }
1844 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1845 }
1846 #endif // INCLUDE_JVMCI
1847 }
1848
1849
1850 // First JavaThread specific code executed by a new Java thread.
1851 void JavaThread::pre_run() {
1852 // empty - see comments in run()
1853 }
1854
1855 // The main routine called by a new Java thread. This isn't overridden
1856 // by subclasses, instead different subclasses define a different "entry_point"
1857 // which defines the actual logic for that kind of thread.
1858 void JavaThread::run() {
1859 // initialize thread-local alloc buffer related fields
1860 this->initialize_tlab();
1861
1862 // Used to test validity of stack trace backs.
1863 // This can't be moved into pre_run() else we invalidate
1864 // the requirement that thread_main_inner is lower on
1865 // the stack. Consequently all the initialization logic
1866 // stays here in run() rather than pre_run().
1867 this->record_base_of_stack_pointer();
1868
1869 this->create_stack_guard_pages();
1870
1871 this->cache_global_variables();
1872
1873 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1874 // in the VM. Change thread state from _thread_new to _thread_in_vm
1875 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1876 // Before a thread is on the threads list it is always safe, so after leaving the
1877 // _thread_new we should emit a instruction barrier. The distance to modified code
1878 // from here is probably far enough, but this is consistent and safe.
1879 OrderAccess::cross_modify_fence();
1880
1881 assert(JavaThread::current() == this, "sanity check");
1882 assert(!Thread::current()->owns_locks(), "sanity check");
1883
1884 DTRACE_THREAD_PROBE(start, this);
1885
1886 // This operation might block. We call that after all safepoint checks for a new thread has
1887 // been completed.
1888 this->set_active_handles(JNIHandleBlock::allocate_block());
1889
1890 if (JvmtiExport::should_post_thread_life()) {
1891 JvmtiExport::post_thread_start(this);
1892
1893 }
1894
1895 // We call another function to do the rest so we are sure that the stack addresses used
1896 // from there will be lower than the stack base just computed.
1897 thread_main_inner();
1898 }
1899
1900 void JavaThread::thread_main_inner() {
1901 assert(JavaThread::current() == this, "sanity check");
1902 assert(this->threadObj() != NULL, "just checking");
1903
1904 // Execute thread entry point unless this thread has a pending exception
1905 // or has been stopped before starting.
1906 // Note: Due to JVM_StopThread we can have pending exceptions already!
1907 if (!this->has_pending_exception() &&
1908 !java_lang_Thread::is_stillborn(this->threadObj())) {
1909 {
1910 ResourceMark rm(this);
1911 this->set_native_thread_name(this->get_thread_name());
1912 }
1913 HandleMark hm(this);
1914 this->entry_point()(this, this);
1915 }
1916
1917 DTRACE_THREAD_PROBE(stop, this);
1918
1919 // Cleanup is handled in post_run()
1920 }
1921
1922 // Shared teardown for all JavaThreads
1923 void JavaThread::post_run() {
1924 this->exit(false);
1925 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1926 // for any shared tear-down.
1927 this->smr_delete();
1928 }
1929
1930 static void ensure_join(JavaThread* thread) {
1931 // We do not need to grab the Threads_lock, since we are operating on ourself.
1932 Handle threadObj(thread, thread->threadObj());
1933 assert(threadObj.not_null(), "java thread object must exist");
1934 ObjectLocker lock(threadObj, thread);
1935 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1936 thread->clear_pending_exception();
1937 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1938 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1939 // Clear the native thread instance - this makes isAlive return false and allows the join()
1940 // to complete once we've done the notify_all below
1941 java_lang_Thread::set_thread(threadObj(), NULL);
1942 lock.notify_all(thread);
1943 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1944 thread->clear_pending_exception();
1945 }
1946
1947 static bool is_daemon(oop threadObj) {
1948 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1949 }
1950
1951 // For any new cleanup additions, please check to see if they need to be applied to
1952 // cleanup_failed_attach_current_thread as well.
1953 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1954 assert(this == JavaThread::current(), "thread consistency check");
1955
1956 elapsedTimer _timer_exit_phase1;
1957 elapsedTimer _timer_exit_phase2;
1958 elapsedTimer _timer_exit_phase3;
1959 elapsedTimer _timer_exit_phase4;
1960
1961 if (log_is_enabled(Debug, os, thread, timer)) {
1962 _timer_exit_phase1.start();
1963 }
1964
1965 HandleMark hm(this);
1966 Handle uncaught_exception(this, this->pending_exception());
1967 this->clear_pending_exception();
1968 Handle threadObj(this, this->threadObj());
1969 assert(threadObj.not_null(), "Java thread object should be created");
1970
1971 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1972 {
1973 EXCEPTION_MARK;
1974
1975 CLEAR_PENDING_EXCEPTION;
1976 }
1977 if (!destroy_vm) {
1978 if (uncaught_exception.not_null()) {
1979 EXCEPTION_MARK;
1980 // Call method Thread.dispatchUncaughtException().
1981 Klass* thread_klass = SystemDictionary::Thread_klass();
1982 JavaValue result(T_VOID);
1983 JavaCalls::call_virtual(&result,
1984 threadObj, thread_klass,
1985 vmSymbols::dispatchUncaughtException_name(),
1986 vmSymbols::throwable_void_signature(),
1987 uncaught_exception,
1988 THREAD);
1989 if (HAS_PENDING_EXCEPTION) {
1990 ResourceMark rm(this);
1991 jio_fprintf(defaultStream::error_stream(),
1992 "\nException: %s thrown from the UncaughtExceptionHandler"
1993 " in thread \"%s\"\n",
1994 pending_exception()->klass()->external_name(),
1995 get_thread_name());
1996 CLEAR_PENDING_EXCEPTION;
1997 }
1998 }
1999 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2000
2001 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2002 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2003 // is deprecated anyhow.
2004 if (!is_Compiler_thread()) {
2005 int count = 3;
2006 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2007 EXCEPTION_MARK;
2008 JavaValue result(T_VOID);
2009 Klass* thread_klass = SystemDictionary::Thread_klass();
2010 JavaCalls::call_virtual(&result,
2011 threadObj, thread_klass,
2012 vmSymbols::exit_method_name(),
2013 vmSymbols::void_method_signature(),
2014 THREAD);
2015 CLEAR_PENDING_EXCEPTION;
2016 }
2017 }
2018 // notify JVMTI
2019 if (JvmtiExport::should_post_thread_life()) {
2020 JvmtiExport::post_thread_end(this);
2021 }
2022
2023 // We have notified the agents that we are exiting, before we go on,
2024 // we must check for a pending external suspend request and honor it
2025 // in order to not surprise the thread that made the suspend request.
2026 while (true) {
2027 {
2028 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2029 if (!is_external_suspend()) {
2030 set_terminated(_thread_exiting);
2031 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2032 break;
2033 }
2034 // Implied else:
2035 // Things get a little tricky here. We have a pending external
2036 // suspend request, but we are holding the SR_lock so we
2037 // can't just self-suspend. So we temporarily drop the lock
2038 // and then self-suspend.
2039 }
2040
2041 ThreadBlockInVM tbivm(this);
2042 java_suspend_self();
2043
2044 // We're done with this suspend request, but we have to loop around
2045 // and check again. Eventually we will get SR_lock without a pending
2046 // external suspend request and will be able to mark ourselves as
2047 // exiting.
2048 }
2049 // no more external suspends are allowed at this point
2050 } else {
2051 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2052 // before_exit() has already posted JVMTI THREAD_END events
2053 }
2054
2055 if (log_is_enabled(Debug, os, thread, timer)) {
2056 _timer_exit_phase1.stop();
2057 _timer_exit_phase2.start();
2058 }
2059
2060 // Capture daemon status before the thread is marked as terminated.
2061 bool daemon = is_daemon(threadObj());
2062
2063 // Notify waiters on thread object. This has to be done after exit() is called
2064 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2065 // group should have the destroyed bit set before waiters are notified).
2066 ensure_join(this);
2067 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2068
2069 if (log_is_enabled(Debug, os, thread, timer)) {
2070 _timer_exit_phase2.stop();
2071 _timer_exit_phase3.start();
2072 }
2073 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2074 // held by this thread must be released. The spec does not distinguish
2075 // between JNI-acquired and regular Java monitors. We can only see
2076 // regular Java monitors here if monitor enter-exit matching is broken.
2077 //
2078 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2079 // ObjectSynchronizer::release_monitors_owned_by_thread().
2080 if (exit_type == jni_detach) {
2081 // Sanity check even though JNI DetachCurrentThread() would have
2082 // returned JNI_ERR if there was a Java frame. JavaThread exit
2083 // should be done executing Java code by the time we get here.
2084 assert(!this->has_last_Java_frame(),
2085 "should not have a Java frame when detaching or exiting");
2086 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2087 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2088 }
2089
2090 // These things needs to be done while we are still a Java Thread. Make sure that thread
2091 // is in a consistent state, in case GC happens
2092 JFR_ONLY(Jfr::on_thread_exit(this);)
2093
2094 if (active_handles() != NULL) {
2095 JNIHandleBlock* block = active_handles();
2096 set_active_handles(NULL);
2097 JNIHandleBlock::release_block(block);
2098 }
2099
2100 if (free_handle_block() != NULL) {
2101 JNIHandleBlock* block = free_handle_block();
2102 set_free_handle_block(NULL);
2103 JNIHandleBlock::release_block(block);
2104 }
2105
2106 // These have to be removed while this is still a valid thread.
2107 remove_stack_guard_pages();
2108
2109 if (UseTLAB) {
2110 tlab().retire();
2111 }
2112
2113 if (JvmtiEnv::environments_might_exist()) {
2114 JvmtiExport::cleanup_thread(this);
2115 }
2116
2117 // We must flush any deferred card marks and other various GC barrier
2118 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2119 // before removing a thread from the list of active threads.
2120 BarrierSet::barrier_set()->on_thread_detach(this);
2121
2122 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2123 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2124 os::current_thread_id());
2125
2126 if (log_is_enabled(Debug, os, thread, timer)) {
2127 _timer_exit_phase3.stop();
2128 _timer_exit_phase4.start();
2129 }
2130 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2131 Threads::remove(this, daemon);
2132
2133 if (log_is_enabled(Debug, os, thread, timer)) {
2134 _timer_exit_phase4.stop();
2135 ResourceMark rm(this);
2136 log_debug(os, thread, timer)("name='%s'"
2137 ", exit-phase1=" JLONG_FORMAT
2138 ", exit-phase2=" JLONG_FORMAT
2139 ", exit-phase3=" JLONG_FORMAT
2140 ", exit-phase4=" JLONG_FORMAT,
2141 get_thread_name(),
2142 _timer_exit_phase1.milliseconds(),
2143 _timer_exit_phase2.milliseconds(),
2144 _timer_exit_phase3.milliseconds(),
2145 _timer_exit_phase4.milliseconds());
2146 }
2147 }
2148
2149 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2150 if (active_handles() != NULL) {
2151 JNIHandleBlock* block = active_handles();
2152 set_active_handles(NULL);
2153 JNIHandleBlock::release_block(block);
2154 }
2155
2156 if (free_handle_block() != NULL) {
2157 JNIHandleBlock* block = free_handle_block();
2158 set_free_handle_block(NULL);
2159 JNIHandleBlock::release_block(block);
2160 }
2161
2162 // These have to be removed while this is still a valid thread.
2163 remove_stack_guard_pages();
2164
2165 if (UseTLAB) {
2166 tlab().retire();
2167 }
2168
2169 BarrierSet::barrier_set()->on_thread_detach(this);
2170
2171 Threads::remove(this, is_daemon);
2172 this->smr_delete();
2173 }
2174
2175 JavaThread* JavaThread::active() {
2176 Thread* thread = Thread::current();
2177 if (thread->is_Java_thread()) {
2178 return (JavaThread*) thread;
2179 } else {
2180 assert(thread->is_VM_thread(), "this must be a vm thread");
2181 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2182 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2183 assert(ret->is_Java_thread(), "must be a Java thread");
2184 return ret;
2185 }
2186 }
2187
2188 bool JavaThread::is_lock_owned(address adr) const {
2189 if (Thread::is_lock_owned(adr)) return true;
2190
2191 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2192 if (chunk->contains(adr)) return true;
2193 }
2194
2195 return false;
2196 }
2197
2198
2199 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2200 chunk->set_next(monitor_chunks());
2201 set_monitor_chunks(chunk);
2202 }
2203
2204 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2205 guarantee(monitor_chunks() != NULL, "must be non empty");
2206 if (monitor_chunks() == chunk) {
2207 set_monitor_chunks(chunk->next());
2208 } else {
2209 MonitorChunk* prev = monitor_chunks();
2210 while (prev->next() != chunk) prev = prev->next();
2211 prev->set_next(chunk->next());
2212 }
2213 }
2214
2215 // JVM support.
2216
2217 // Note: this function shouldn't block if it's called in
2218 // _thread_in_native_trans state (such as from
2219 // check_special_condition_for_native_trans()).
2220 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2221
2222 if (has_last_Java_frame() && has_async_condition()) {
2223 // If we are at a polling page safepoint (not a poll return)
2224 // then we must defer async exception because live registers
2225 // will be clobbered by the exception path. Poll return is
2226 // ok because the call we a returning from already collides
2227 // with exception handling registers and so there is no issue.
2228 // (The exception handling path kills call result registers but
2229 // this is ok since the exception kills the result anyway).
2230
2231 if (is_at_poll_safepoint()) {
2232 // if the code we are returning to has deoptimized we must defer
2233 // the exception otherwise live registers get clobbered on the
2234 // exception path before deoptimization is able to retrieve them.
2235 //
2236 RegisterMap map(this, false);
2237 frame caller_fr = last_frame().sender(&map);
2238 assert(caller_fr.is_compiled_frame(), "what?");
2239 if (caller_fr.is_deoptimized_frame()) {
2240 log_info(exceptions)("deferred async exception at compiled safepoint");
2241 return;
2242 }
2243 }
2244 }
2245
2246 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2247 if (condition == _no_async_condition) {
2248 // Conditions have changed since has_special_runtime_exit_condition()
2249 // was called:
2250 // - if we were here only because of an external suspend request,
2251 // then that was taken care of above (or cancelled) so we are done
2252 // - if we were here because of another async request, then it has
2253 // been cleared between the has_special_runtime_exit_condition()
2254 // and now so again we are done
2255 return;
2256 }
2257
2258 // Check for pending async. exception
2259 if (_pending_async_exception != NULL) {
2260 // Only overwrite an already pending exception, if it is not a threadDeath.
2261 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2262
2263 // We cannot call Exceptions::_throw(...) here because we cannot block
2264 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2265
2266 LogTarget(Info, exceptions) lt;
2267 if (lt.is_enabled()) {
2268 ResourceMark rm;
2269 LogStream ls(lt);
2270 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2271 if (has_last_Java_frame()) {
2272 frame f = last_frame();
2273 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2274 }
2275 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2276 }
2277 _pending_async_exception = NULL;
2278 clear_has_async_exception();
2279 }
2280 }
2281
2282 if (check_unsafe_error &&
2283 condition == _async_unsafe_access_error && !has_pending_exception()) {
2284 condition = _no_async_condition; // done
2285 switch (thread_state()) {
2286 case _thread_in_vm: {
2287 JavaThread* THREAD = this;
2288 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2289 }
2290 case _thread_in_native: {
2291 ThreadInVMfromNative tiv(this);
2292 JavaThread* THREAD = this;
2293 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2294 }
2295 case _thread_in_Java: {
2296 ThreadInVMfromJava tiv(this);
2297 JavaThread* THREAD = this;
2298 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2299 }
2300 default:
2301 ShouldNotReachHere();
2302 }
2303 }
2304
2305 assert(condition == _no_async_condition || has_pending_exception() ||
2306 (!check_unsafe_error && condition == _async_unsafe_access_error),
2307 "must have handled the async condition, if no exception");
2308 }
2309
2310 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2311
2312 // Check for pending external suspend.
2313 if (is_external_suspend_with_lock()) {
2314 frame_anchor()->make_walkable(this);
2315 java_suspend_self_with_safepoint_check();
2316 }
2317
2318 // We might be here for reasons in addition to the self-suspend request
2319 // so check for other async requests.
2320 if (check_asyncs) {
2321 check_and_handle_async_exceptions();
2322 }
2323
2324 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2325 }
2326
2327 void JavaThread::send_thread_stop(oop java_throwable) {
2328 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2329 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2330 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2331
2332 // Do not throw asynchronous exceptions against the compiler thread
2333 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2334 if (!can_call_java()) return;
2335
2336 {
2337 // Actually throw the Throwable against the target Thread - however
2338 // only if there is no thread death exception installed already.
2339 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2340 // If the topmost frame is a runtime stub, then we are calling into
2341 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2342 // must deoptimize the caller before continuing, as the compiled exception handler table
2343 // may not be valid
2344 if (has_last_Java_frame()) {
2345 frame f = last_frame();
2346 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2347 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2348 RegisterMap reg_map(this, UseBiasedLocking);
2349 frame compiled_frame = f.sender(®_map);
2350 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2351 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2352 }
2353 }
2354 }
2355
2356 // Set async. pending exception in thread.
2357 set_pending_async_exception(java_throwable);
2358
2359 if (log_is_enabled(Info, exceptions)) {
2360 ResourceMark rm;
2361 log_info(exceptions)("Pending Async. exception installed of type: %s",
2362 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2363 }
2364 // for AbortVMOnException flag
2365 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2366 }
2367 }
2368
2369
2370 // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2371 java_lang_Thread::set_interrupted(threadObj(), true);
2372 this->interrupt();
2373 }
2374
2375 // External suspension mechanism.
2376 //
2377 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2378 // to any VM_locks and it is at a transition
2379 // Self-suspension will happen on the transition out of the vm.
2380 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2381 //
2382 // Guarantees on return:
2383 // + Target thread will not execute any new bytecode (that's why we need to
2384 // force a safepoint)
2385 // + Target thread will not enter any new monitors
2386 //
2387 void JavaThread::java_suspend() {
2388 ThreadsListHandle tlh;
2389 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2390 return;
2391 }
2392
2393 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2394 if (!is_external_suspend()) {
2395 // a racing resume has cancelled us; bail out now
2396 return;
2397 }
2398
2399 // suspend is done
2400 uint32_t debug_bits = 0;
2401 // Warning: is_ext_suspend_completed() may temporarily drop the
2402 // SR_lock to allow the thread to reach a stable thread state if
2403 // it is currently in a transient thread state.
2404 if (is_ext_suspend_completed(false /* !called_by_wait */,
2405 SuspendRetryDelay, &debug_bits)) {
2406 return;
2407 }
2408 }
2409
2410 if (Thread::current() == this) {
2411 // Safely self-suspend.
2412 // If we don't do this explicitly it will implicitly happen
2413 // before we transition back to Java, and on some other thread-state
2414 // transition paths, but not as we exit a JVM TI SuspendThread call.
2415 // As SuspendThread(current) must not return (until resumed) we must
2416 // self-suspend here.
2417 ThreadBlockInVM tbivm(this);
2418 java_suspend_self();
2419 } else {
2420 VM_ThreadSuspend vm_suspend;
2421 VMThread::execute(&vm_suspend);
2422 }
2423 }
2424
2425 // Part II of external suspension.
2426 // A JavaThread self suspends when it detects a pending external suspend
2427 // request. This is usually on transitions. It is also done in places
2428 // where continuing to the next transition would surprise the caller,
2429 // e.g., monitor entry.
2430 //
2431 // Returns the number of times that the thread self-suspended.
2432 //
2433 // Note: DO NOT call java_suspend_self() when you just want to block current
2434 // thread. java_suspend_self() is the second stage of cooperative
2435 // suspension for external suspend requests and should only be used
2436 // to complete an external suspend request.
2437 //
2438 int JavaThread::java_suspend_self() {
2439 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2440 int ret = 0;
2441
2442 // we are in the process of exiting so don't suspend
2443 if (is_exiting()) {
2444 clear_external_suspend();
2445 return ret;
2446 }
2447
2448 assert(_anchor.walkable() ||
2449 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2450 "must have walkable stack");
2451
2452 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2453
2454 assert(!this->is_ext_suspended(),
2455 "a thread trying to self-suspend should not already be suspended");
2456
2457 if (this->is_suspend_equivalent()) {
2458 // If we are self-suspending as a result of the lifting of a
2459 // suspend equivalent condition, then the suspend_equivalent
2460 // flag is not cleared until we set the ext_suspended flag so
2461 // that wait_for_ext_suspend_completion() returns consistent
2462 // results.
2463 this->clear_suspend_equivalent();
2464 }
2465
2466 // A racing resume may have cancelled us before we grabbed SR_lock
2467 // above. Or another external suspend request could be waiting for us
2468 // by the time we return from SR_lock()->wait(). The thread
2469 // that requested the suspension may already be trying to walk our
2470 // stack and if we return now, we can change the stack out from under
2471 // it. This would be a "bad thing (TM)" and cause the stack walker
2472 // to crash. We stay self-suspended until there are no more pending
2473 // external suspend requests.
2474 while (is_external_suspend()) {
2475 ret++;
2476 this->set_ext_suspended();
2477
2478 // _ext_suspended flag is cleared by java_resume()
2479 while (is_ext_suspended()) {
2480 ml.wait();
2481 }
2482 }
2483 return ret;
2484 }
2485
2486 // Helper routine to set up the correct thread state before calling java_suspend_self.
2487 // This is called when regular thread-state transition helpers can't be used because
2488 // we can be in various states, in particular _thread_in_native_trans.
2489 // Because this thread is external suspended the safepoint code will count it as at
2490 // a safepoint, regardless of what its actual current thread-state is. But
2491 // is_ext_suspend_completed() may be waiting to see a thread transition from
2492 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2493 // to _thread_blocked. The problem with setting thread state directly is that a
2494 // safepoint could happen just after java_suspend_self() returns after being resumed,
2495 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2496 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2497 // However, not all initial-states are allowed when performing a safepoint check, as we
2498 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2499 // only _thread_in_native is possible when executing this code (based on our two callers).
2500 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2501 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2502 // and so we don't need the explicit safepoint check.
2503
2504 void JavaThread::java_suspend_self_with_safepoint_check() {
2505 assert(this == Thread::current(), "invariant");
2506 JavaThreadState state = thread_state();
2507 set_thread_state(_thread_blocked);
2508 java_suspend_self();
2509 set_thread_state_fence(state);
2510 // Since we are not using a regular thread-state transition helper here,
2511 // we must manually emit the instruction barrier after leaving a safe state.
2512 OrderAccess::cross_modify_fence();
2513 if (state != _thread_in_native) {
2514 SafepointMechanism::block_if_requested(this);
2515 }
2516 }
2517
2518 #ifdef ASSERT
2519 // Verify the JavaThread has not yet been published in the Threads::list, and
2520 // hence doesn't need protection from concurrent access at this stage.
2521 void JavaThread::verify_not_published() {
2522 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2523 // since an unpublished JavaThread doesn't participate in the
2524 // Thread-SMR protocol for keeping a ThreadsList alive.
2525 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2526 }
2527 #endif
2528
2529 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2530 // progress or when _suspend_flags is non-zero.
2531 // Current thread needs to self-suspend if there is a suspend request and/or
2532 // block if a safepoint is in progress.
2533 // Async exception ISN'T checked.
2534 // Note only the ThreadInVMfromNative transition can call this function
2535 // directly and when thread state is _thread_in_native_trans
2536 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2537 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2538
2539 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2540
2541 if (thread->is_external_suspend()) {
2542 thread->java_suspend_self_with_safepoint_check();
2543 } else {
2544 SafepointMechanism::block_if_requested(thread);
2545 }
2546
2547 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2548 }
2549
2550 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2551 // progress or when _suspend_flags is non-zero.
2552 // Current thread needs to self-suspend if there is a suspend request and/or
2553 // block if a safepoint is in progress.
2554 // Also check for pending async exception (not including unsafe access error).
2555 // Note only the native==>VM/Java barriers can call this function and when
2556 // thread state is _thread_in_native_trans.
2557 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2558 check_safepoint_and_suspend_for_native_trans(thread);
2559
2560 if (thread->has_async_exception()) {
2561 // We are in _thread_in_native_trans state, don't handle unsafe
2562 // access error since that may block.
2563 thread->check_and_handle_async_exceptions(false);
2564 }
2565 }
2566
2567 // This is a variant of the normal
2568 // check_special_condition_for_native_trans with slightly different
2569 // semantics for use by critical native wrappers. It does all the
2570 // normal checks but also performs the transition back into
2571 // thread_in_Java state. This is required so that critical natives
2572 // can potentially block and perform a GC if they are the last thread
2573 // exiting the GCLocker.
2574 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2575 check_special_condition_for_native_trans(thread);
2576
2577 // Finish the transition
2578 thread->set_thread_state(_thread_in_Java);
2579
2580 if (thread->do_critical_native_unlock()) {
2581 ThreadInVMfromJavaNoAsyncException tiv(thread);
2582 GCLocker::unlock_critical(thread);
2583 thread->clear_critical_native_unlock();
2584 }
2585 }
2586
2587 // We need to guarantee the Threads_lock here, since resumes are not
2588 // allowed during safepoint synchronization
2589 // Can only resume from an external suspension
2590 void JavaThread::java_resume() {
2591 assert_locked_or_safepoint(Threads_lock);
2592
2593 // Sanity check: thread is gone, has started exiting or the thread
2594 // was not externally suspended.
2595 ThreadsListHandle tlh;
2596 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2597 return;
2598 }
2599
2600 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2601
2602 clear_external_suspend();
2603
2604 if (is_ext_suspended()) {
2605 clear_ext_suspended();
2606 SR_lock()->notify_all();
2607 }
2608 }
2609
2610 size_t JavaThread::_stack_red_zone_size = 0;
2611 size_t JavaThread::_stack_yellow_zone_size = 0;
2612 size_t JavaThread::_stack_reserved_zone_size = 0;
2613 size_t JavaThread::_stack_shadow_zone_size = 0;
2614
2615 void JavaThread::create_stack_guard_pages() {
2616 if (!os::uses_stack_guard_pages() ||
2617 _stack_guard_state != stack_guard_unused ||
2618 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2619 log_info(os, thread)("Stack guard page creation for thread "
2620 UINTX_FORMAT " disabled", os::current_thread_id());
2621 return;
2622 }
2623 address low_addr = stack_end();
2624 size_t len = stack_guard_zone_size();
2625
2626 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2627 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2628
2629 int must_commit = os::must_commit_stack_guard_pages();
2630 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2631
2632 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2633 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2634 return;
2635 }
2636
2637 if (os::guard_memory((char *) low_addr, len)) {
2638 _stack_guard_state = stack_guard_enabled;
2639 } else {
2640 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2641 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2642 if (os::uncommit_memory((char *) low_addr, len)) {
2643 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2644 }
2645 return;
2646 }
2647
2648 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2649 PTR_FORMAT "-" PTR_FORMAT ".",
2650 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2651 }
2652
2653 void JavaThread::remove_stack_guard_pages() {
2654 assert(Thread::current() == this, "from different thread");
2655 if (_stack_guard_state == stack_guard_unused) return;
2656 address low_addr = stack_end();
2657 size_t len = stack_guard_zone_size();
2658
2659 if (os::must_commit_stack_guard_pages()) {
2660 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2661 _stack_guard_state = stack_guard_unused;
2662 } else {
2663 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2664 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2665 return;
2666 }
2667 } else {
2668 if (_stack_guard_state == stack_guard_unused) return;
2669 if (os::unguard_memory((char *) low_addr, len)) {
2670 _stack_guard_state = stack_guard_unused;
2671 } else {
2672 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2673 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2674 return;
2675 }
2676 }
2677
2678 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2679 PTR_FORMAT "-" PTR_FORMAT ".",
2680 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2681 }
2682
2683 void JavaThread::enable_stack_reserved_zone() {
2684 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2685
2686 // The base notation is from the stack's point of view, growing downward.
2687 // We need to adjust it to work correctly with guard_memory()
2688 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2689
2690 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2691 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2692
2693 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2694 _stack_guard_state = stack_guard_enabled;
2695 } else {
2696 warning("Attempt to guard stack reserved zone failed.");
2697 }
2698 enable_register_stack_guard();
2699 }
2700
2701 void JavaThread::disable_stack_reserved_zone() {
2702 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2703
2704 // Simply return if called for a thread that does not use guard pages.
2705 if (_stack_guard_state != stack_guard_enabled) return;
2706
2707 // The base notation is from the stack's point of view, growing downward.
2708 // We need to adjust it to work correctly with guard_memory()
2709 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2710
2711 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2712 _stack_guard_state = stack_guard_reserved_disabled;
2713 } else {
2714 warning("Attempt to unguard stack reserved zone failed.");
2715 }
2716 disable_register_stack_guard();
2717 }
2718
2719 void JavaThread::enable_stack_yellow_reserved_zone() {
2720 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2721 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2722
2723 // The base notation is from the stacks point of view, growing downward.
2724 // We need to adjust it to work correctly with guard_memory()
2725 address base = stack_red_zone_base();
2726
2727 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2728 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2729
2730 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2731 _stack_guard_state = stack_guard_enabled;
2732 } else {
2733 warning("Attempt to guard stack yellow zone failed.");
2734 }
2735 enable_register_stack_guard();
2736 }
2737
2738 void JavaThread::disable_stack_yellow_reserved_zone() {
2739 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2740 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2741
2742 // Simply return if called for a thread that does not use guard pages.
2743 if (_stack_guard_state == stack_guard_unused) return;
2744
2745 // The base notation is from the stacks point of view, growing downward.
2746 // We need to adjust it to work correctly with guard_memory()
2747 address base = stack_red_zone_base();
2748
2749 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2750 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2751 } else {
2752 warning("Attempt to unguard stack yellow zone failed.");
2753 }
2754 disable_register_stack_guard();
2755 }
2756
2757 void JavaThread::enable_stack_red_zone() {
2758 // The base notation is from the stacks point of view, growing downward.
2759 // We need to adjust it to work correctly with guard_memory()
2760 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2761 address base = stack_red_zone_base() - stack_red_zone_size();
2762
2763 guarantee(base < stack_base(), "Error calculating stack red zone");
2764 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2765
2766 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2767 warning("Attempt to guard stack red zone failed.");
2768 }
2769 }
2770
2771 void JavaThread::disable_stack_red_zone() {
2772 // The base notation is from the stacks point of view, growing downward.
2773 // We need to adjust it to work correctly with guard_memory()
2774 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2775 address base = stack_red_zone_base() - stack_red_zone_size();
2776 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2777 warning("Attempt to unguard stack red zone failed.");
2778 }
2779 }
2780
2781 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2782 // ignore is there is no stack
2783 if (!has_last_Java_frame()) return;
2784 // traverse the stack frames. Starts from top frame.
2785 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2786 frame* fr = fst.current();
2787 f(fr, fst.register_map());
2788 }
2789 }
2790
2791
2792 #ifndef PRODUCT
2793 // Deoptimization
2794 // Function for testing deoptimization
2795 void JavaThread::deoptimize() {
2796 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2797 StackFrameStream fst(this, UseBiasedLocking);
2798 bool deopt = false; // Dump stack only if a deopt actually happens.
2799 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2800 // Iterate over all frames in the thread and deoptimize
2801 for (; !fst.is_done(); fst.next()) {
2802 if (fst.current()->can_be_deoptimized()) {
2803
2804 if (only_at) {
2805 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2806 // consists of comma or carriage return separated numbers so
2807 // search for the current bci in that string.
2808 address pc = fst.current()->pc();
2809 nmethod* nm = (nmethod*) fst.current()->cb();
2810 ScopeDesc* sd = nm->scope_desc_at(pc);
2811 char buffer[8];
2812 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2813 size_t len = strlen(buffer);
2814 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2815 while (found != NULL) {
2816 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2817 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2818 // Check that the bci found is bracketed by terminators.
2819 break;
2820 }
2821 found = strstr(found + 1, buffer);
2822 }
2823 if (!found) {
2824 continue;
2825 }
2826 }
2827
2828 if (DebugDeoptimization && !deopt) {
2829 deopt = true; // One-time only print before deopt
2830 tty->print_cr("[BEFORE Deoptimization]");
2831 trace_frames();
2832 trace_stack();
2833 }
2834 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2835 }
2836 }
2837
2838 if (DebugDeoptimization && deopt) {
2839 tty->print_cr("[AFTER Deoptimization]");
2840 trace_frames();
2841 }
2842 }
2843
2844
2845 // Make zombies
2846 void JavaThread::make_zombies() {
2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848 if (fst.current()->can_be_deoptimized()) {
2849 // it is a Java nmethod
2850 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2851 nm->make_not_entrant();
2852 }
2853 }
2854 }
2855 #endif // PRODUCT
2856
2857
2858 void JavaThread::deoptimize_marked_methods() {
2859 if (!has_last_Java_frame()) return;
2860 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2861 StackFrameStream fst(this, UseBiasedLocking);
2862 for (; !fst.is_done(); fst.next()) {
2863 if (fst.current()->should_be_deoptimized()) {
2864 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2865 }
2866 }
2867 }
2868
2869 // If the caller is a NamedThread, then remember, in the current scope,
2870 // the given JavaThread in its _processed_thread field.
2871 class RememberProcessedThread: public StackObj {
2872 NamedThread* _cur_thr;
2873 public:
2874 RememberProcessedThread(JavaThread* jthr) {
2875 Thread* thread = Thread::current();
2876 if (thread->is_Named_thread()) {
2877 _cur_thr = (NamedThread *)thread;
2878 _cur_thr->set_processed_thread(jthr);
2879 } else {
2880 _cur_thr = NULL;
2881 }
2882 }
2883
2884 ~RememberProcessedThread() {
2885 if (_cur_thr) {
2886 _cur_thr->set_processed_thread(NULL);
2887 }
2888 }
2889 };
2890
2891 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2892 // Verify that the deferred card marks have been flushed.
2893 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2894
2895 // Traverse the GCHandles
2896 Thread::oops_do(f, cf);
2897
2898 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2899 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2900
2901 if (has_last_Java_frame()) {
2902 // Record JavaThread to GC thread
2903 RememberProcessedThread rpt(this);
2904
2905 // traverse the registered growable array
2906 if (_array_for_gc != NULL) {
2907 for (int index = 0; index < _array_for_gc->length(); index++) {
2908 f->do_oop(_array_for_gc->adr_at(index));
2909 }
2910 }
2911
2912 // Traverse the monitor chunks
2913 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2914 chunk->oops_do(f);
2915 }
2916
2917 // Traverse the execution stack
2918 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2919 fst.current()->oops_do(f, cf, fst.register_map());
2920 }
2921 }
2922
2923 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2924 // If we have deferred set_locals there might be oops waiting to be
2925 // written
2926 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2927 if (list != NULL) {
2928 for (int i = 0; i < list->length(); i++) {
2929 list->at(i)->oops_do(f);
2930 }
2931 }
2932
2933 // Traverse instance variables at the end since the GC may be moving things
2934 // around using this function
2935 f->do_oop((oop*) &_threadObj);
2936 f->do_oop((oop*) &_vm_result);
2937 f->do_oop((oop*) &_exception_oop);
2938 f->do_oop((oop*) &_pending_async_exception);
2939
2940 if (jvmti_thread_state() != NULL) {
2941 jvmti_thread_state()->oops_do(f);
2942 }
2943 }
2944
2945 #ifdef ASSERT
2946 void JavaThread::verify_states_for_handshake() {
2947 // This checks that the thread has a correct frame state during a handshake.
2948 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2949 (has_last_Java_frame() && java_call_counter() > 0),
2950 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2951 has_last_Java_frame(), java_call_counter());
2952 }
2953 #endif
2954
2955 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2956 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2957 (has_last_Java_frame() && java_call_counter() > 0),
2958 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2959 has_last_Java_frame(), java_call_counter());
2960
2961 if (has_last_Java_frame()) {
2962 // Traverse the execution stack
2963 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2964 fst.current()->nmethods_do(cf);
2965 }
2966 }
2967 }
2968
2969 void JavaThread::metadata_do(MetadataClosure* f) {
2970 if (has_last_Java_frame()) {
2971 // Traverse the execution stack to call f() on the methods in the stack
2972 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2973 fst.current()->metadata_do(f);
2974 }
2975 } else if (is_Compiler_thread()) {
2976 // need to walk ciMetadata in current compile tasks to keep alive.
2977 CompilerThread* ct = (CompilerThread*)this;
2978 if (ct->env() != NULL) {
2979 ct->env()->metadata_do(f);
2980 }
2981 CompileTask* task = ct->task();
2982 if (task != NULL) {
2983 task->metadata_do(f);
2984 }
2985 }
2986 }
2987
2988 // Printing
2989 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2990 switch (_thread_state) {
2991 case _thread_uninitialized: return "_thread_uninitialized";
2992 case _thread_new: return "_thread_new";
2993 case _thread_new_trans: return "_thread_new_trans";
2994 case _thread_in_native: return "_thread_in_native";
2995 case _thread_in_native_trans: return "_thread_in_native_trans";
2996 case _thread_in_vm: return "_thread_in_vm";
2997 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2998 case _thread_in_Java: return "_thread_in_Java";
2999 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3000 case _thread_blocked: return "_thread_blocked";
3001 case _thread_blocked_trans: return "_thread_blocked_trans";
3002 default: return "unknown thread state";
3003 }
3004 }
3005
3006 #ifndef PRODUCT
3007 void JavaThread::print_thread_state_on(outputStream *st) const {
3008 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3009 };
3010 #endif // PRODUCT
3011
3012 // Called by Threads::print() for VM_PrintThreads operation
3013 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3014 st->print_raw("\"");
3015 st->print_raw(get_thread_name());
3016 st->print_raw("\" ");
3017 oop thread_oop = threadObj();
3018 if (thread_oop != NULL) {
3019 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3020 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3021 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3022 }
3023 Thread::print_on(st, print_extended_info);
3024 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3025 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3026 if (thread_oop != NULL) {
3027 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3028 }
3029 #ifndef PRODUCT
3030 _safepoint_state->print_on(st);
3031 #endif // PRODUCT
3032 if (is_Compiler_thread()) {
3033 CompileTask *task = ((CompilerThread*)this)->task();
3034 if (task != NULL) {
3035 st->print(" Compiling: ");
3036 task->print(st, NULL, true, false);
3037 } else {
3038 st->print(" No compile task");
3039 }
3040 st->cr();
3041 }
3042 }
3043
3044 void JavaThread::print() const { print_on(tty); }
3045
3046 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3047 st->print("%s", get_thread_name_string(buf, buflen));
3048 }
3049
3050 // Called by fatal error handler. The difference between this and
3051 // JavaThread::print() is that we can't grab lock or allocate memory.
3052 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3053 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3054 oop thread_obj = threadObj();
3055 if (thread_obj != NULL) {
3056 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3057 }
3058 st->print(" [");
3059 st->print("%s", _get_thread_state_name(_thread_state));
3060 if (osthread()) {
3061 st->print(", id=%d", osthread()->thread_id());
3062 }
3063 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3064 p2i(stack_end()), p2i(stack_base()));
3065 st->print("]");
3066
3067 ThreadsSMRSupport::print_info_on(this, st);
3068 return;
3069 }
3070
3071 // Verification
3072
3073 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3074
3075 void JavaThread::verify() {
3076 // Verify oops in the thread.
3077 oops_do(&VerifyOopClosure::verify_oop, NULL);
3078
3079 // Verify the stack frames.
3080 frames_do(frame_verify);
3081 }
3082
3083 // CR 6300358 (sub-CR 2137150)
3084 // Most callers of this method assume that it can't return NULL but a
3085 // thread may not have a name whilst it is in the process of attaching to
3086 // the VM - see CR 6412693, and there are places where a JavaThread can be
3087 // seen prior to having it's threadObj set (eg JNI attaching threads and
3088 // if vm exit occurs during initialization). These cases can all be accounted
3089 // for such that this method never returns NULL.
3090 const char* JavaThread::get_thread_name() const {
3091 #ifdef ASSERT
3092 // early safepoints can hit while current thread does not yet have TLS
3093 if (!SafepointSynchronize::is_at_safepoint()) {
3094 Thread *cur = Thread::current();
3095 if (!(cur->is_Java_thread() && cur == this)) {
3096 // Current JavaThreads are allowed to get their own name without
3097 // the Threads_lock.
3098 assert_locked_or_safepoint(Threads_lock);
3099 }
3100 }
3101 #endif // ASSERT
3102 return get_thread_name_string();
3103 }
3104
3105 // Returns a non-NULL representation of this thread's name, or a suitable
3106 // descriptive string if there is no set name
3107 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3108 const char* name_str;
3109 oop thread_obj = threadObj();
3110 if (thread_obj != NULL) {
3111 oop name = java_lang_Thread::name(thread_obj);
3112 if (name != NULL) {
3113 if (buf == NULL) {
3114 name_str = java_lang_String::as_utf8_string(name);
3115 } else {
3116 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3117 }
3118 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3119 name_str = "<no-name - thread is attaching>";
3120 } else {
3121 name_str = Thread::name();
3122 }
3123 } else {
3124 name_str = Thread::name();
3125 }
3126 assert(name_str != NULL, "unexpected NULL thread name");
3127 return name_str;
3128 }
3129
3130 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3131
3132 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3133 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3134 // Link Java Thread object <-> C++ Thread
3135
3136 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3137 // and put it into a new Handle. The Handle "thread_oop" can then
3138 // be used to pass the C++ thread object to other methods.
3139
3140 // Set the Java level thread object (jthread) field of the
3141 // new thread (a JavaThread *) to C++ thread object using the
3142 // "thread_oop" handle.
3143
3144 // Set the thread field (a JavaThread *) of the
3145 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3146
3147 Handle thread_oop(Thread::current(),
3148 JNIHandles::resolve_non_null(jni_thread));
3149 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3150 "must be initialized");
3151 set_threadObj(thread_oop());
3152 java_lang_Thread::set_thread(thread_oop(), this);
3153
3154 if (prio == NoPriority) {
3155 prio = java_lang_Thread::priority(thread_oop());
3156 assert(prio != NoPriority, "A valid priority should be present");
3157 }
3158
3159 // Push the Java priority down to the native thread; needs Threads_lock
3160 Thread::set_priority(this, prio);
3161
3162 // Add the new thread to the Threads list and set it in motion.
3163 // We must have threads lock in order to call Threads::add.
3164 // It is crucial that we do not block before the thread is
3165 // added to the Threads list for if a GC happens, then the java_thread oop
3166 // will not be visited by GC.
3167 Threads::add(this);
3168 }
3169
3170 oop JavaThread::current_park_blocker() {
3171 // Support for JSR-166 locks
3172 oop thread_oop = threadObj();
3173 if (thread_oop != NULL) {
3174 return java_lang_Thread::park_blocker(thread_oop);
3175 }
3176 return NULL;
3177 }
3178
3179
3180 void JavaThread::print_stack_on(outputStream* st) {
3181 if (!has_last_Java_frame()) return;
3182 ResourceMark rm;
3183 HandleMark hm;
3184
3185 RegisterMap reg_map(this);
3186 vframe* start_vf = last_java_vframe(®_map);
3187 int count = 0;
3188 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3189 if (f->is_java_frame()) {
3190 javaVFrame* jvf = javaVFrame::cast(f);
3191 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3192
3193 // Print out lock information
3194 if (JavaMonitorsInStackTrace) {
3195 jvf->print_lock_info_on(st, count);
3196 }
3197 } else {
3198 // Ignore non-Java frames
3199 }
3200
3201 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3202 count++;
3203 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3204 }
3205 }
3206
3207
3208 // JVMTI PopFrame support
3209 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3210 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3211 if (in_bytes(size_in_bytes) != 0) {
3212 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3213 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3214 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3215 }
3216 }
3217
3218 void* JavaThread::popframe_preserved_args() {
3219 return _popframe_preserved_args;
3220 }
3221
3222 ByteSize JavaThread::popframe_preserved_args_size() {
3223 return in_ByteSize(_popframe_preserved_args_size);
3224 }
3225
3226 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3227 int sz = in_bytes(popframe_preserved_args_size());
3228 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3229 return in_WordSize(sz / wordSize);
3230 }
3231
3232 void JavaThread::popframe_free_preserved_args() {
3233 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3234 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3235 _popframe_preserved_args = NULL;
3236 _popframe_preserved_args_size = 0;
3237 }
3238
3239 #ifndef PRODUCT
3240
3241 void JavaThread::trace_frames() {
3242 tty->print_cr("[Describe stack]");
3243 int frame_no = 1;
3244 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3245 tty->print(" %d. ", frame_no++);
3246 fst.current()->print_value_on(tty, this);
3247 tty->cr();
3248 }
3249 }
3250
3251 class PrintAndVerifyOopClosure: public OopClosure {
3252 protected:
3253 template <class T> inline void do_oop_work(T* p) {
3254 oop obj = RawAccess<>::oop_load(p);
3255 if (obj == NULL) return;
3256 tty->print(INTPTR_FORMAT ": ", p2i(p));
3257 if (oopDesc::is_oop_or_null(obj)) {
3258 if (obj->is_objArray()) {
3259 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3260 } else {
3261 obj->print();
3262 }
3263 } else {
3264 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3265 }
3266 tty->cr();
3267 }
3268 public:
3269 virtual void do_oop(oop* p) { do_oop_work(p); }
3270 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3271 };
3272
3273 #ifdef ASSERT
3274 // Print or validate the layout of stack frames
3275 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3276 ResourceMark rm;
3277 PRESERVE_EXCEPTION_MARK;
3278 FrameValues values;
3279 int frame_no = 0;
3280 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3281 fst.current()->describe(values, ++frame_no);
3282 if (depth == frame_no) break;
3283 }
3284 if (validate_only) {
3285 values.validate();
3286 } else {
3287 tty->print_cr("[Describe stack layout]");
3288 values.print(this);
3289 }
3290 }
3291 #endif
3292
3293 void JavaThread::trace_stack_from(vframe* start_vf) {
3294 ResourceMark rm;
3295 int vframe_no = 1;
3296 for (vframe* f = start_vf; f; f = f->sender()) {
3297 if (f->is_java_frame()) {
3298 javaVFrame::cast(f)->print_activation(vframe_no++);
3299 } else {
3300 f->print();
3301 }
3302 if (vframe_no > StackPrintLimit) {
3303 tty->print_cr("...<more frames>...");
3304 return;
3305 }
3306 }
3307 }
3308
3309
3310 void JavaThread::trace_stack() {
3311 if (!has_last_Java_frame()) return;
3312 ResourceMark rm;
3313 HandleMark hm;
3314 RegisterMap reg_map(this);
3315 trace_stack_from(last_java_vframe(®_map));
3316 }
3317
3318
3319 #endif // PRODUCT
3320
3321
3322 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3323 assert(reg_map != NULL, "a map must be given");
3324 frame f = last_frame();
3325 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3326 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3327 }
3328 return NULL;
3329 }
3330
3331
3332 Klass* JavaThread::security_get_caller_class(int depth) {
3333 vframeStream vfst(this);
3334 vfst.security_get_caller_frame(depth);
3335 if (!vfst.at_end()) {
3336 return vfst.method()->method_holder();
3337 }
3338 return NULL;
3339 }
3340
3341 // java.lang.Thread.sleep support
3342 // Returns true if sleep time elapsed as expected, and false
3343 // if the thread was interrupted.
3344 bool JavaThread::sleep(jlong millis) {
3345 assert(this == Thread::current(), "thread consistency check");
3346
3347 ParkEvent * const slp = this->_SleepEvent;
3348 // Because there can be races with thread interruption sending an unpark()
3349 // to the event, we explicitly reset it here to avoid an immediate return.
3350 // The actual interrupt state will be checked before we park().
3351 slp->reset();
3352 // Thread interruption establishes a happens-before ordering in the
3353 // Java Memory Model, so we need to ensure we synchronize with the
3354 // interrupt state.
3355 OrderAccess::fence();
3356
3357 jlong prevtime = os::javaTimeNanos();
3358
3359 for (;;) {
3360 // interruption has precedence over timing out
3361 if (this->is_interrupted(true)) {
3362 return false;
3363 }
3364
3365 if (millis <= 0) {
3366 return true;
3367 }
3368
3369 {
3370 ThreadBlockInVM tbivm(this);
3371 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3372
3373 this->set_suspend_equivalent();
3374 // cleared by handle_special_suspend_equivalent_condition() or
3375 // java_suspend_self() via check_and_wait_while_suspended()
3376
3377 slp->park(millis);
3378
3379 // were we externally suspended while we were waiting?
3380 this->check_and_wait_while_suspended();
3381 }
3382
3383 // Update elapsed time tracking
3384 jlong newtime = os::javaTimeNanos();
3385 if (newtime - prevtime < 0) {
3386 // time moving backwards, should only happen if no monotonic clock
3387 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3388 assert(!os::supports_monotonic_clock(),
3389 "unexpected time moving backwards detected in JavaThread::sleep()");
3390 } else {
3391 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3392 }
3393 prevtime = newtime;
3394 }
3395 }
3396
3397 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3398 assert(thread->is_Compiler_thread(), "must be compiler thread");
3399 CompileBroker::compiler_thread_loop();
3400 }
3401
3402 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3403 NMethodSweeper::sweeper_loop();
3404 }
3405
3406 // Create a CompilerThread
3407 CompilerThread::CompilerThread(CompileQueue* queue,
3408 CompilerCounters* counters)
3409 : JavaThread(&compiler_thread_entry) {
3410 _env = NULL;
3411 _log = NULL;
3412 _task = NULL;
3413 _queue = queue;
3414 _counters = counters;
3415 _buffer_blob = NULL;
3416 _compiler = NULL;
3417
3418 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3419 resource_area()->bias_to(mtCompiler);
3420
3421 #ifndef PRODUCT
3422 _ideal_graph_printer = NULL;
3423 #endif
3424 }
3425
3426 CompilerThread::~CompilerThread() {
3427 // Delete objects which were allocated on heap.
3428 delete _counters;
3429 }
3430
3431 bool CompilerThread::can_call_java() const {
3432 return _compiler != NULL && _compiler->is_jvmci();
3433 }
3434
3435 // Create sweeper thread
3436 CodeCacheSweeperThread::CodeCacheSweeperThread()
3437 : JavaThread(&sweeper_thread_entry) {
3438 _scanned_compiled_method = NULL;
3439 }
3440
3441 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3442 JavaThread::oops_do(f, cf);
3443 if (_scanned_compiled_method != NULL && cf != NULL) {
3444 // Safepoints can occur when the sweeper is scanning an nmethod so
3445 // process it here to make sure it isn't unloaded in the middle of
3446 // a scan.
3447 cf->do_code_blob(_scanned_compiled_method);
3448 }
3449 }
3450
3451 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3452 JavaThread::nmethods_do(cf);
3453 if (_scanned_compiled_method != NULL && cf != NULL) {
3454 // Safepoints can occur when the sweeper is scanning an nmethod so
3455 // process it here to make sure it isn't unloaded in the middle of
3456 // a scan.
3457 cf->do_code_blob(_scanned_compiled_method);
3458 }
3459 }
3460
3461
3462 // ======= Threads ========
3463
3464 // The Threads class links together all active threads, and provides
3465 // operations over all threads. It is protected by the Threads_lock,
3466 // which is also used in other global contexts like safepointing.
3467 // ThreadsListHandles are used to safely perform operations on one
3468 // or more threads without the risk of the thread exiting during the
3469 // operation.
3470 //
3471 // Note: The Threads_lock is currently more widely used than we
3472 // would like. We are actively migrating Threads_lock uses to other
3473 // mechanisms in order to reduce Threads_lock contention.
3474
3475 int Threads::_number_of_threads = 0;
3476 int Threads::_number_of_non_daemon_threads = 0;
3477 int Threads::_return_code = 0;
3478 uintx Threads::_thread_claim_token = 1; // Never zero.
3479 size_t JavaThread::_stack_size_at_create = 0;
3480
3481 #ifdef ASSERT
3482 bool Threads::_vm_complete = false;
3483 #endif
3484
3485 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3486 Prefetch::read((void*)addr, prefetch_interval);
3487 return *addr;
3488 }
3489
3490 // Possibly the ugliest for loop the world has seen. C++ does not allow
3491 // multiple types in the declaration section of the for loop. In this case
3492 // we are only dealing with pointers and hence can cast them. It looks ugly
3493 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3494 #define DO_JAVA_THREADS(LIST, X) \
3495 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3496 *MACRO_list = (JavaThread*)(LIST), \
3497 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3498 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3499 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3500 MACRO_current_p != MACRO_end; \
3501 MACRO_current_p++, \
3502 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3503
3504 // All JavaThreads
3505 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3506
3507 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3508 void Threads::non_java_threads_do(ThreadClosure* tc) {
3509 NoSafepointVerifier nsv;
3510 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3511 tc->do_thread(njti.current());
3512 }
3513 }
3514
3515 // All JavaThreads
3516 void Threads::java_threads_do(ThreadClosure* tc) {
3517 assert_locked_or_safepoint(Threads_lock);
3518 // ALL_JAVA_THREADS iterates through all JavaThreads.
3519 ALL_JAVA_THREADS(p) {
3520 tc->do_thread(p);
3521 }
3522 }
3523
3524 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3525 assert_locked_or_safepoint(Threads_lock);
3526 java_threads_do(tc);
3527 tc->do_thread(VMThread::vm_thread());
3528 }
3529
3530 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3531 void Threads::threads_do(ThreadClosure* tc) {
3532 assert_locked_or_safepoint(Threads_lock);
3533 java_threads_do(tc);
3534 non_java_threads_do(tc);
3535 }
3536
3537 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3538 uintx claim_token = Threads::thread_claim_token();
3539 ALL_JAVA_THREADS(p) {
3540 if (p->claim_threads_do(is_par, claim_token)) {
3541 tc->do_thread(p);
3542 }
3543 }
3544 VMThread* vmt = VMThread::vm_thread();
3545 if (vmt->claim_threads_do(is_par, claim_token)) {
3546 tc->do_thread(vmt);
3547 }
3548 }
3549
3550 // The system initialization in the library has three phases.
3551 //
3552 // Phase 1: java.lang.System class initialization
3553 // java.lang.System is a primordial class loaded and initialized
3554 // by the VM early during startup. java.lang.System.<clinit>
3555 // only does registerNatives and keeps the rest of the class
3556 // initialization work later until thread initialization completes.
3557 //
3558 // System.initPhase1 initializes the system properties, the static
3559 // fields in, out, and err. Set up java signal handlers, OS-specific
3560 // system settings, and thread group of the main thread.
3561 static void call_initPhase1(TRAPS) {
3562 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3563 JavaValue result(T_VOID);
3564 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3565 vmSymbols::void_method_signature(), CHECK);
3566 }
3567
3568 // Phase 2. Module system initialization
3569 // This will initialize the module system. Only java.base classes
3570 // can be loaded until phase 2 completes.
3571 //
3572 // Call System.initPhase2 after the compiler initialization and jsr292
3573 // classes get initialized because module initialization runs a lot of java
3574 // code, that for performance reasons, should be compiled. Also, this will
3575 // enable the startup code to use lambda and other language features in this
3576 // phase and onward.
3577 //
3578 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3579 static void call_initPhase2(TRAPS) {
3580 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3581
3582 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3583
3584 JavaValue result(T_INT);
3585 JavaCallArguments args;
3586 args.push_int(DisplayVMOutputToStderr);
3587 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3588 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3589 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3590 if (result.get_jint() != JNI_OK) {
3591 vm_exit_during_initialization(); // no message or exception
3592 }
3593
3594 universe_post_module_init();
3595 }
3596
3597 // Phase 3. final setup - set security manager, system class loader and TCCL
3598 //
3599 // This will instantiate and set the security manager, set the system class
3600 // loader as well as the thread context class loader. The security manager
3601 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3602 // other modules or the application's classpath.
3603 static void call_initPhase3(TRAPS) {
3604 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3605 JavaValue result(T_VOID);
3606 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3607 vmSymbols::void_method_signature(), CHECK);
3608 }
3609
3610 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3611 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3612
3613 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3614 create_vm_init_libraries();
3615 }
3616
3617 initialize_class(vmSymbols::java_lang_String(), CHECK);
3618
3619 // Inject CompactStrings value after the static initializers for String ran.
3620 java_lang_String::set_compact_strings(CompactStrings);
3621
3622 // Initialize java_lang.System (needed before creating the thread)
3623 initialize_class(vmSymbols::java_lang_System(), CHECK);
3624 // The VM creates & returns objects of this class. Make sure it's initialized.
3625 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3626 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3627 Handle thread_group = create_initial_thread_group(CHECK);
3628 Universe::set_main_thread_group(thread_group());
3629 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3630 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3631 main_thread->set_threadObj(thread_object);
3632
3633 // Set thread status to running since main thread has
3634 // been started and running.
3635 java_lang_Thread::set_thread_status(thread_object,
3636 java_lang_Thread::RUNNABLE);
3637
3638 // The VM creates objects of this class.
3639 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3640
3641 #ifdef ASSERT
3642 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3643 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3644 #endif
3645
3646 // initialize the hardware-specific constants needed by Unsafe
3647 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3648 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3649
3650 // The VM preresolves methods to these classes. Make sure that they get initialized
3651 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3652 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3653
3654 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3655 call_initPhase1(CHECK);
3656
3657 // get the Java runtime name after java.lang.System is initialized
3658 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3659 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3660
3661 // an instance of OutOfMemory exception has been allocated earlier
3662 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3663 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3664 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3665 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3666 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3667 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3668 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3669 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3670
3671 // Eager box cache initialization only if AOT is on and any library is loaded.
3672 AOTLoader::initialize_box_caches(CHECK);
3673 }
3674
3675 void Threads::initialize_jsr292_core_classes(TRAPS) {
3676 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3677
3678 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3679 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3680 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3681 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3682 }
3683
3684 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3685 extern void JDK_Version_init();
3686
3687 // Preinitialize version info.
3688 VM_Version::early_initialize();
3689
3690 // Check version
3691 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3692
3693 // Initialize library-based TLS
3694 ThreadLocalStorage::init();
3695
3696 // Initialize the output stream module
3697 ostream_init();
3698
3699 // Process java launcher properties.
3700 Arguments::process_sun_java_launcher_properties(args);
3701
3702 // Initialize the os module
3703 os::init();
3704
3705 // Record VM creation timing statistics
3706 TraceVmCreationTime create_vm_timer;
3707 create_vm_timer.start();
3708
3709 // Initialize system properties.
3710 Arguments::init_system_properties();
3711
3712 // So that JDK version can be used as a discriminator when parsing arguments
3713 JDK_Version_init();
3714
3715 // Update/Initialize System properties after JDK version number is known
3716 Arguments::init_version_specific_system_properties();
3717
3718 // Make sure to initialize log configuration *before* parsing arguments
3719 LogConfiguration::initialize(create_vm_timer.begin_time());
3720
3721 // Parse arguments
3722 // Note: this internally calls os::init_container_support()
3723 jint parse_result = Arguments::parse(args);
3724 if (parse_result != JNI_OK) return parse_result;
3725
3726 os::init_before_ergo();
3727
3728 jint ergo_result = Arguments::apply_ergo();
3729 if (ergo_result != JNI_OK) return ergo_result;
3730
3731 // Final check of all ranges after ergonomics which may change values.
3732 if (!JVMFlagRangeList::check_ranges()) {
3733 return JNI_EINVAL;
3734 }
3735
3736 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3737 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3738 if (!constraint_result) {
3739 return JNI_EINVAL;
3740 }
3741
3742 JVMFlagWriteableList::mark_startup();
3743
3744 if (PauseAtStartup) {
3745 os::pause();
3746 }
3747
3748 HOTSPOT_VM_INIT_BEGIN();
3749
3750 // Timing (must come after argument parsing)
3751 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3752
3753 // Initialize the os module after parsing the args
3754 jint os_init_2_result = os::init_2();
3755 if (os_init_2_result != JNI_OK) return os_init_2_result;
3756
3757 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3758 // Initialize assert poison page mechanism.
3759 if (ShowRegistersOnAssert) {
3760 initialize_assert_poison();
3761 }
3762 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3763
3764 SafepointMechanism::initialize();
3765
3766 jint adjust_after_os_result = Arguments::adjust_after_os();
3767 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3768
3769 // Initialize output stream logging
3770 ostream_init_log();
3771
3772 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3773 // Must be before create_vm_init_agents()
3774 if (Arguments::init_libraries_at_startup()) {
3775 convert_vm_init_libraries_to_agents();
3776 }
3777
3778 // Launch -agentlib/-agentpath and converted -Xrun agents
3779 if (Arguments::init_agents_at_startup()) {
3780 create_vm_init_agents();
3781 }
3782
3783 // Initialize Threads state
3784 _number_of_threads = 0;
3785 _number_of_non_daemon_threads = 0;
3786
3787 // Initialize global data structures and create system classes in heap
3788 vm_init_globals();
3789
3790 #if INCLUDE_JVMCI
3791 if (JVMCICounterSize > 0) {
3792 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3793 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3794 } else {
3795 JavaThread::_jvmci_old_thread_counters = NULL;
3796 }
3797 #endif // INCLUDE_JVMCI
3798
3799 // Attach the main thread to this os thread
3800 JavaThread* main_thread = new JavaThread();
3801 main_thread->set_thread_state(_thread_in_vm);
3802 main_thread->initialize_thread_current();
3803 // must do this before set_active_handles
3804 main_thread->record_stack_base_and_size();
3805 main_thread->register_thread_stack_with_NMT();
3806 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3807
3808 if (!main_thread->set_as_starting_thread()) {
3809 vm_shutdown_during_initialization(
3810 "Failed necessary internal allocation. Out of swap space");
3811 main_thread->smr_delete();
3812 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3813 return JNI_ENOMEM;
3814 }
3815
3816 // Enable guard page *after* os::create_main_thread(), otherwise it would
3817 // crash Linux VM, see notes in os_linux.cpp.
3818 main_thread->create_stack_guard_pages();
3819
3820 // Initialize Java-Level synchronization subsystem
3821 ObjectMonitor::Initialize();
3822
3823 // Initialize global modules
3824 jint status = init_globals();
3825 if (status != JNI_OK) {
3826 main_thread->smr_delete();
3827 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3828 return status;
3829 }
3830
3831 JFR_ONLY(Jfr::on_vm_init();)
3832
3833 // Should be done after the heap is fully created
3834 main_thread->cache_global_variables();
3835
3836 HandleMark hm;
3837
3838 { MutexLocker mu(Threads_lock);
3839 Threads::add(main_thread);
3840 }
3841
3842 // Any JVMTI raw monitors entered in onload will transition into
3843 // real raw monitor. VM is setup enough here for raw monitor enter.
3844 JvmtiExport::transition_pending_onload_raw_monitors();
3845
3846 // Create the VMThread
3847 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3848
3849 VMThread::create();
3850 Thread* vmthread = VMThread::vm_thread();
3851
3852 if (!os::create_thread(vmthread, os::vm_thread)) {
3853 vm_exit_during_initialization("Cannot create VM thread. "
3854 "Out of system resources.");
3855 }
3856
3857 // Wait for the VM thread to become ready, and VMThread::run to initialize
3858 // Monitors can have spurious returns, must always check another state flag
3859 {
3860 MonitorLocker ml(Notify_lock);
3861 os::start_thread(vmthread);
3862 while (vmthread->active_handles() == NULL) {
3863 ml.wait();
3864 }
3865 }
3866 }
3867
3868 assert(Universe::is_fully_initialized(), "not initialized");
3869 if (VerifyDuringStartup) {
3870 // Make sure we're starting with a clean slate.
3871 VM_Verify verify_op;
3872 VMThread::execute(&verify_op);
3873 }
3874
3875 // We need this to update the java.vm.info property in case any flags used
3876 // to initially define it have been changed. This is needed for both CDS and
3877 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3878 // is initially computed. See Abstract_VM_Version::vm_info_string().
3879 // This update must happen before we initialize the java classes, but
3880 // after any initialization logic that might modify the flags.
3881 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3882
3883 Thread* THREAD = Thread::current();
3884
3885 // Always call even when there are not JVMTI environments yet, since environments
3886 // may be attached late and JVMTI must track phases of VM execution
3887 JvmtiExport::enter_early_start_phase();
3888
3889 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3890 JvmtiExport::post_early_vm_start();
3891
3892 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3893
3894 quicken_jni_functions();
3895
3896 // No more stub generation allowed after that point.
3897 StubCodeDesc::freeze();
3898
3899 // Set flag that basic initialization has completed. Used by exceptions and various
3900 // debug stuff, that does not work until all basic classes have been initialized.
3901 set_init_completed();
3902
3903 LogConfiguration::post_initialize();
3904 Metaspace::post_initialize();
3905
3906 HOTSPOT_VM_INIT_END();
3907
3908 // record VM initialization completion time
3909 #if INCLUDE_MANAGEMENT
3910 Management::record_vm_init_completed();
3911 #endif // INCLUDE_MANAGEMENT
3912
3913 // Signal Dispatcher needs to be started before VMInit event is posted
3914 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3915
3916 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3917 if (!DisableAttachMechanism) {
3918 AttachListener::vm_start();
3919 if (StartAttachListener || AttachListener::init_at_startup()) {
3920 AttachListener::init();
3921 }
3922 }
3923
3924 // Launch -Xrun agents
3925 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3926 // back-end can launch with -Xdebug -Xrunjdwp.
3927 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3928 create_vm_init_libraries();
3929 }
3930
3931 if (CleanChunkPoolAsync) {
3932 Chunk::start_chunk_pool_cleaner_task();
3933 }
3934
3935
3936 // initialize compiler(s)
3937 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3938 #if INCLUDE_JVMCI
3939 bool force_JVMCI_intialization = false;
3940 if (EnableJVMCI) {
3941 // Initialize JVMCI eagerly when it is explicitly requested.
3942 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3943 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3944
3945 if (!force_JVMCI_intialization) {
3946 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3947 // compilations via JVMCI will not actually block until JVMCI is initialized.
3948 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3949 }
3950 }
3951 #endif
3952 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3953 // Postpone completion of compiler initialization to after JVMCI
3954 // is initialized to avoid timeouts of blocking compilations.
3955 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3956 CompileBroker::compilation_init_phase2();
3957 }
3958 #endif
3959
3960 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3961 // It is done after compilers are initialized, because otherwise compilations of
3962 // signature polymorphic MH intrinsics can be missed
3963 // (see SystemDictionary::find_method_handle_intrinsic).
3964 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3965
3966 // This will initialize the module system. Only java.base classes can be
3967 // loaded until phase 2 completes
3968 call_initPhase2(CHECK_JNI_ERR);
3969
3970 // Always call even when there are not JVMTI environments yet, since environments
3971 // may be attached late and JVMTI must track phases of VM execution
3972 JvmtiExport::enter_start_phase();
3973
3974 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3975 JvmtiExport::post_vm_start();
3976
3977 // Final system initialization including security manager and system class loader
3978 call_initPhase3(CHECK_JNI_ERR);
3979
3980 // cache the system and platform class loaders
3981 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3982
3983 #if INCLUDE_CDS
3984 // capture the module path info from the ModuleEntryTable
3985 ClassLoader::initialize_module_path(THREAD);
3986 #endif
3987
3988 #if INCLUDE_JVMCI
3989 if (force_JVMCI_intialization) {
3990 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3991 CompileBroker::compilation_init_phase2();
3992 }
3993 #endif
3994
3995 // Always call even when there are not JVMTI environments yet, since environments
3996 // may be attached late and JVMTI must track phases of VM execution
3997 JvmtiExport::enter_live_phase();
3998
3999 // Make perfmemory accessible
4000 PerfMemory::set_accessible(true);
4001
4002 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4003 JvmtiExport::post_vm_initialized();
4004
4005 JFR_ONLY(Jfr::on_vm_start();)
4006
4007 #if INCLUDE_MANAGEMENT
4008 Management::initialize(THREAD);
4009
4010 if (HAS_PENDING_EXCEPTION) {
4011 // management agent fails to start possibly due to
4012 // configuration problem and is responsible for printing
4013 // stack trace if appropriate. Simply exit VM.
4014 vm_exit(1);
4015 }
4016 #endif // INCLUDE_MANAGEMENT
4017
4018 if (MemProfiling) MemProfiler::engage();
4019 StatSampler::engage();
4020 if (CheckJNICalls) JniPeriodicChecker::engage();
4021
4022 BiasedLocking::init();
4023
4024 #if INCLUDE_RTM_OPT
4025 RTMLockingCounters::init();
4026 #endif
4027
4028 call_postVMInitHook(THREAD);
4029 // The Java side of PostVMInitHook.run must deal with all
4030 // exceptions and provide means of diagnosis.
4031 if (HAS_PENDING_EXCEPTION) {
4032 CLEAR_PENDING_EXCEPTION;
4033 }
4034
4035 {
4036 MutexLocker ml(PeriodicTask_lock);
4037 // Make sure the WatcherThread can be started by WatcherThread::start()
4038 // or by dynamic enrollment.
4039 WatcherThread::make_startable();
4040 // Start up the WatcherThread if there are any periodic tasks
4041 // NOTE: All PeriodicTasks should be registered by now. If they
4042 // aren't, late joiners might appear to start slowly (we might
4043 // take a while to process their first tick).
4044 if (PeriodicTask::num_tasks() > 0) {
4045 WatcherThread::start();
4046 }
4047 }
4048
4049 create_vm_timer.end();
4050 #ifdef ASSERT
4051 _vm_complete = true;
4052 #endif
4053
4054 if (DumpSharedSpaces) {
4055 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4056 ShouldNotReachHere();
4057 }
4058
4059 return JNI_OK;
4060 }
4061
4062 // type for the Agent_OnLoad and JVM_OnLoad entry points
4063 extern "C" {
4064 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4065 }
4066 // Find a command line agent library and return its entry point for
4067 // -agentlib: -agentpath: -Xrun
4068 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4069 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4070 const char *on_load_symbols[],
4071 size_t num_symbol_entries) {
4072 OnLoadEntry_t on_load_entry = NULL;
4073 void *library = NULL;
4074
4075 if (!agent->valid()) {
4076 char buffer[JVM_MAXPATHLEN];
4077 char ebuf[1024] = "";
4078 const char *name = agent->name();
4079 const char *msg = "Could not find agent library ";
4080
4081 // First check to see if agent is statically linked into executable
4082 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4083 library = agent->os_lib();
4084 } else if (agent->is_absolute_path()) {
4085 library = os::dll_load(name, ebuf, sizeof ebuf);
4086 if (library == NULL) {
4087 const char *sub_msg = " in absolute path, with error: ";
4088 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4089 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4090 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4091 // If we can't find the agent, exit.
4092 vm_exit_during_initialization(buf, NULL);
4093 FREE_C_HEAP_ARRAY(char, buf);
4094 }
4095 } else {
4096 // Try to load the agent from the standard dll directory
4097 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4098 name)) {
4099 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4100 }
4101 if (library == NULL) { // Try the library path directory.
4102 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4103 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4104 }
4105 if (library == NULL) {
4106 const char *sub_msg = " on the library path, with error: ";
4107 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4108
4109 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4110 strlen(ebuf) + strlen(sub_msg2) + 1;
4111 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4112 if (!agent->is_instrument_lib()) {
4113 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4114 } else {
4115 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4116 }
4117 // If we can't find the agent, exit.
4118 vm_exit_during_initialization(buf, NULL);
4119 FREE_C_HEAP_ARRAY(char, buf);
4120 }
4121 }
4122 }
4123 agent->set_os_lib(library);
4124 agent->set_valid();
4125 }
4126
4127 // Find the OnLoad function.
4128 on_load_entry =
4129 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4130 false,
4131 on_load_symbols,
4132 num_symbol_entries));
4133 return on_load_entry;
4134 }
4135
4136 // Find the JVM_OnLoad entry point
4137 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4138 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4139 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4140 }
4141
4142 // Find the Agent_OnLoad entry point
4143 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4144 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4145 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4146 }
4147
4148 // For backwards compatibility with -Xrun
4149 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4150 // treated like -agentpath:
4151 // Must be called before agent libraries are created
4152 void Threads::convert_vm_init_libraries_to_agents() {
4153 AgentLibrary* agent;
4154 AgentLibrary* next;
4155
4156 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4157 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4158 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4159
4160 // If there is an JVM_OnLoad function it will get called later,
4161 // otherwise see if there is an Agent_OnLoad
4162 if (on_load_entry == NULL) {
4163 on_load_entry = lookup_agent_on_load(agent);
4164 if (on_load_entry != NULL) {
4165 // switch it to the agent list -- so that Agent_OnLoad will be called,
4166 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4167 Arguments::convert_library_to_agent(agent);
4168 } else {
4169 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4170 }
4171 }
4172 }
4173 }
4174
4175 // Create agents for -agentlib: -agentpath: and converted -Xrun
4176 // Invokes Agent_OnLoad
4177 // Called very early -- before JavaThreads exist
4178 void Threads::create_vm_init_agents() {
4179 extern struct JavaVM_ main_vm;
4180 AgentLibrary* agent;
4181
4182 JvmtiExport::enter_onload_phase();
4183
4184 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4185 // CDS dumping does not support native JVMTI agent.
4186 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4187 if (Arguments::is_dumping_archive()) {
4188 if(!agent->is_instrument_lib()) {
4189 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4190 } else if (!AllowArchivingWithJavaAgent) {
4191 vm_exit_during_cds_dumping(
4192 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4193 }
4194 }
4195
4196 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4197
4198 if (on_load_entry != NULL) {
4199 // Invoke the Agent_OnLoad function
4200 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4201 if (err != JNI_OK) {
4202 vm_exit_during_initialization("agent library failed to init", agent->name());
4203 }
4204 } else {
4205 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4206 }
4207 }
4208
4209 JvmtiExport::enter_primordial_phase();
4210 }
4211
4212 extern "C" {
4213 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4214 }
4215
4216 void Threads::shutdown_vm_agents() {
4217 // Send any Agent_OnUnload notifications
4218 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4219 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4220 extern struct JavaVM_ main_vm;
4221 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4222
4223 // Find the Agent_OnUnload function.
4224 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4225 os::find_agent_function(agent,
4226 false,
4227 on_unload_symbols,
4228 num_symbol_entries));
4229
4230 // Invoke the Agent_OnUnload function
4231 if (unload_entry != NULL) {
4232 JavaThread* thread = JavaThread::current();
4233 ThreadToNativeFromVM ttn(thread);
4234 HandleMark hm(thread);
4235 (*unload_entry)(&main_vm);
4236 }
4237 }
4238 }
4239
4240 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4241 // Invokes JVM_OnLoad
4242 void Threads::create_vm_init_libraries() {
4243 extern struct JavaVM_ main_vm;
4244 AgentLibrary* agent;
4245
4246 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4247 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4248
4249 if (on_load_entry != NULL) {
4250 // Invoke the JVM_OnLoad function
4251 JavaThread* thread = JavaThread::current();
4252 ThreadToNativeFromVM ttn(thread);
4253 HandleMark hm(thread);
4254 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4255 if (err != JNI_OK) {
4256 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4257 }
4258 } else {
4259 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4260 }
4261 }
4262 }
4263
4264
4265 // Last thread running calls java.lang.Shutdown.shutdown()
4266 void JavaThread::invoke_shutdown_hooks() {
4267 HandleMark hm(this);
4268
4269 // We could get here with a pending exception, if so clear it now.
4270 if (this->has_pending_exception()) {
4271 this->clear_pending_exception();
4272 }
4273
4274 EXCEPTION_MARK;
4275 Klass* shutdown_klass =
4276 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4277 THREAD);
4278 if (shutdown_klass != NULL) {
4279 // SystemDictionary::resolve_or_null will return null if there was
4280 // an exception. If we cannot load the Shutdown class, just don't
4281 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4282 // won't be run. Note that if a shutdown hook was registered,
4283 // the Shutdown class would have already been loaded
4284 // (Runtime.addShutdownHook will load it).
4285 JavaValue result(T_VOID);
4286 JavaCalls::call_static(&result,
4287 shutdown_klass,
4288 vmSymbols::shutdown_name(),
4289 vmSymbols::void_method_signature(),
4290 THREAD);
4291 }
4292 CLEAR_PENDING_EXCEPTION;
4293 }
4294
4295 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4296 // the program falls off the end of main(). Another VM exit path is through
4297 // vm_exit() when the program calls System.exit() to return a value or when
4298 // there is a serious error in VM. The two shutdown paths are not exactly
4299 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4300 // and VM_Exit op at VM level.
4301 //
4302 // Shutdown sequence:
4303 // + Shutdown native memory tracking if it is on
4304 // + Wait until we are the last non-daemon thread to execute
4305 // <-- every thing is still working at this moment -->
4306 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4307 // shutdown hooks
4308 // + Call before_exit(), prepare for VM exit
4309 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4310 // currently the only user of this mechanism is File.deleteOnExit())
4311 // > stop StatSampler, watcher thread, CMS threads,
4312 // post thread end and vm death events to JVMTI,
4313 // stop signal thread
4314 // + Call JavaThread::exit(), it will:
4315 // > release JNI handle blocks, remove stack guard pages
4316 // > remove this thread from Threads list
4317 // <-- no more Java code from this thread after this point -->
4318 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4319 // the compiler threads at safepoint
4320 // <-- do not use anything that could get blocked by Safepoint -->
4321 // + Disable tracing at JNI/JVM barriers
4322 // + Set _vm_exited flag for threads that are still running native code
4323 // + Call exit_globals()
4324 // > deletes tty
4325 // > deletes PerfMemory resources
4326 // + Delete this thread
4327 // + Return to caller
4328
4329 bool Threads::destroy_vm() {
4330 JavaThread* thread = JavaThread::current();
4331
4332 #ifdef ASSERT
4333 _vm_complete = false;
4334 #endif
4335 // Wait until we are the last non-daemon thread to execute
4336 { MonitorLocker nu(Threads_lock);
4337 while (Threads::number_of_non_daemon_threads() > 1)
4338 // This wait should make safepoint checks, wait without a timeout,
4339 // and wait as a suspend-equivalent condition.
4340 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4341 }
4342
4343 EventShutdown e;
4344 if (e.should_commit()) {
4345 e.set_reason("No remaining non-daemon Java threads");
4346 e.commit();
4347 }
4348
4349 // Hang forever on exit if we are reporting an error.
4350 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4351 os::infinite_sleep();
4352 }
4353 os::wait_for_keypress_at_exit();
4354
4355 // run Java level shutdown hooks
4356 thread->invoke_shutdown_hooks();
4357
4358 before_exit(thread);
4359
4360 thread->exit(true);
4361
4362 // Stop VM thread.
4363 {
4364 // 4945125 The vm thread comes to a safepoint during exit.
4365 // GC vm_operations can get caught at the safepoint, and the
4366 // heap is unparseable if they are caught. Grab the Heap_lock
4367 // to prevent this. The GC vm_operations will not be able to
4368 // queue until after the vm thread is dead. After this point,
4369 // we'll never emerge out of the safepoint before the VM exits.
4370
4371 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4372
4373 VMThread::wait_for_vm_thread_exit();
4374 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4375 VMThread::destroy();
4376 }
4377
4378 // Now, all Java threads are gone except daemon threads. Daemon threads
4379 // running Java code or in VM are stopped by the Safepoint. However,
4380 // daemon threads executing native code are still running. But they
4381 // will be stopped at native=>Java/VM barriers. Note that we can't
4382 // simply kill or suspend them, as it is inherently deadlock-prone.
4383
4384 VM_Exit::set_vm_exited();
4385
4386 // Clean up ideal graph printers after the VMThread has started
4387 // the final safepoint which will block all the Compiler threads.
4388 // Note that this Thread has already logically exited so the
4389 // clean_up() function's use of a JavaThreadIteratorWithHandle
4390 // would be a problem except set_vm_exited() has remembered the
4391 // shutdown thread which is granted a policy exception.
4392 #if defined(COMPILER2) && !defined(PRODUCT)
4393 IdealGraphPrinter::clean_up();
4394 #endif
4395
4396 notify_vm_shutdown();
4397
4398 // exit_globals() will delete tty
4399 exit_globals();
4400
4401 // We are after VM_Exit::set_vm_exited() so we can't call
4402 // thread->smr_delete() or we will block on the Threads_lock.
4403 // Deleting the shutdown thread here is safe because another
4404 // JavaThread cannot have an active ThreadsListHandle for
4405 // this JavaThread.
4406 delete thread;
4407
4408 #if INCLUDE_JVMCI
4409 if (JVMCICounterSize > 0) {
4410 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4411 }
4412 #endif
4413
4414 LogConfiguration::finalize();
4415
4416 return true;
4417 }
4418
4419
4420 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4421 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4422 return is_supported_jni_version(version);
4423 }
4424
4425
4426 jboolean Threads::is_supported_jni_version(jint version) {
4427 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4428 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4429 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4430 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4431 if (version == JNI_VERSION_9) return JNI_TRUE;
4432 if (version == JNI_VERSION_10) return JNI_TRUE;
4433 return JNI_FALSE;
4434 }
4435
4436
4437 void Threads::add(JavaThread* p, bool force_daemon) {
4438 // The threads lock must be owned at this point
4439 assert(Threads_lock->owned_by_self(), "must have threads lock");
4440
4441 BarrierSet::barrier_set()->on_thread_attach(p);
4442
4443 // Once a JavaThread is added to the Threads list, smr_delete() has
4444 // to be used to delete it. Otherwise we can just delete it directly.
4445 p->set_on_thread_list();
4446
4447 _number_of_threads++;
4448 oop threadObj = p->threadObj();
4449 bool daemon = true;
4450 // Bootstrapping problem: threadObj can be null for initial
4451 // JavaThread (or for threads attached via JNI)
4452 if ((!force_daemon) && !is_daemon((threadObj))) {
4453 _number_of_non_daemon_threads++;
4454 daemon = false;
4455 }
4456
4457 ThreadService::add_thread(p, daemon);
4458
4459 // Maintain fast thread list
4460 ThreadsSMRSupport::add_thread(p);
4461
4462 // Possible GC point.
4463 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4464 }
4465
4466 void Threads::remove(JavaThread* p, bool is_daemon) {
4467
4468 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4469 ObjectSynchronizer::om_flush(p);
4470
4471 // Extra scope needed for Thread_lock, so we can check
4472 // that we do not remove thread without safepoint code notice
4473 { MonitorLocker ml(Threads_lock);
4474
4475 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4476
4477 // Maintain fast thread list
4478 ThreadsSMRSupport::remove_thread(p);
4479
4480 _number_of_threads--;
4481 if (!is_daemon) {
4482 _number_of_non_daemon_threads--;
4483
4484 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4485 // on destroy_vm will wake up.
4486 if (number_of_non_daemon_threads() == 1) {
4487 ml.notify_all();
4488 }
4489 }
4490 ThreadService::remove_thread(p, is_daemon);
4491
4492 // Make sure that safepoint code disregard this thread. This is needed since
4493 // the thread might mess around with locks after this point. This can cause it
4494 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4495 // of this thread since it is removed from the queue.
4496 p->set_terminated_value();
4497 } // unlock Threads_lock
4498
4499 // Since Events::log uses a lock, we grab it outside the Threads_lock
4500 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4501 }
4502
4503 // Operations on the Threads list for GC. These are not explicitly locked,
4504 // but the garbage collector must provide a safe context for them to run.
4505 // In particular, these things should never be called when the Threads_lock
4506 // is held by some other thread. (Note: the Safepoint abstraction also
4507 // uses the Threads_lock to guarantee this property. It also makes sure that
4508 // all threads gets blocked when exiting or starting).
4509
4510 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4511 ALL_JAVA_THREADS(p) {
4512 p->oops_do(f, cf);
4513 }
4514 VMThread::vm_thread()->oops_do(f, cf);
4515 }
4516
4517 void Threads::change_thread_claim_token() {
4518 if (++_thread_claim_token == 0) {
4519 // On overflow of the token counter, there is a risk of future
4520 // collisions between a new global token value and a stale token
4521 // for a thread, because not all iterations visit all threads.
4522 // (Though it's pretty much a theoretical concern for non-trivial
4523 // token counter sizes.) To deal with the possibility, reset all
4524 // the thread tokens to zero on global token overflow.
4525 struct ResetClaims : public ThreadClosure {
4526 virtual void do_thread(Thread* t) {
4527 t->claim_threads_do(false, 0);
4528 }
4529 } reset_claims;
4530 Threads::threads_do(&reset_claims);
4531 // On overflow, update the global token to non-zero, to
4532 // avoid the special "never claimed" initial thread value.
4533 _thread_claim_token = 1;
4534 }
4535 }
4536
4537 #ifdef ASSERT
4538 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4539 const uintx token = t->threads_do_token();
4540 assert(token == expected,
4541 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4542 UINTX_FORMAT, kind, p2i(t), token, expected);
4543 }
4544
4545 void Threads::assert_all_threads_claimed() {
4546 ALL_JAVA_THREADS(p) {
4547 assert_thread_claimed("Thread", p, _thread_claim_token);
4548 }
4549 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4550 }
4551 #endif // ASSERT
4552
4553 class ParallelOopsDoThreadClosure : public ThreadClosure {
4554 private:
4555 OopClosure* _f;
4556 CodeBlobClosure* _cf;
4557 public:
4558 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4559 void do_thread(Thread* t) {
4560 t->oops_do(_f, _cf);
4561 }
4562 };
4563
4564 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4565 ParallelOopsDoThreadClosure tc(f, cf);
4566 possibly_parallel_threads_do(is_par, &tc);
4567 }
4568
4569 void Threads::nmethods_do(CodeBlobClosure* cf) {
4570 ALL_JAVA_THREADS(p) {
4571 // This is used by the code cache sweeper to mark nmethods that are active
4572 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4573 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4574 if(!p->is_Code_cache_sweeper_thread()) {
4575 p->nmethods_do(cf);
4576 }
4577 }
4578 }
4579
4580 void Threads::metadata_do(MetadataClosure* f) {
4581 ALL_JAVA_THREADS(p) {
4582 p->metadata_do(f);
4583 }
4584 }
4585
4586 class ThreadHandlesClosure : public ThreadClosure {
4587 void (*_f)(Metadata*);
4588 public:
4589 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4590 virtual void do_thread(Thread* thread) {
4591 thread->metadata_handles_do(_f);
4592 }
4593 };
4594
4595 void Threads::metadata_handles_do(void f(Metadata*)) {
4596 // Only walk the Handles in Thread.
4597 ThreadHandlesClosure handles_closure(f);
4598 threads_do(&handles_closure);
4599 }
4600
4601 // Get count Java threads that are waiting to enter the specified monitor.
4602 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4603 int count,
4604 address monitor) {
4605 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4606
4607 int i = 0;
4608 DO_JAVA_THREADS(t_list, p) {
4609 if (!p->can_call_java()) continue;
4610
4611 address pending = (address)p->current_pending_monitor();
4612 if (pending == monitor) { // found a match
4613 if (i < count) result->append(p); // save the first count matches
4614 i++;
4615 }
4616 }
4617
4618 return result;
4619 }
4620
4621
4622 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4623 address owner) {
4624 // NULL owner means not locked so we can skip the search
4625 if (owner == NULL) return NULL;
4626
4627 DO_JAVA_THREADS(t_list, p) {
4628 // first, see if owner is the address of a Java thread
4629 if (owner == (address)p) return p;
4630 }
4631
4632 // Cannot assert on lack of success here since this function may be
4633 // used by code that is trying to report useful problem information
4634 // like deadlock detection.
4635 if (UseHeavyMonitors) return NULL;
4636
4637 // If we didn't find a matching Java thread and we didn't force use of
4638 // heavyweight monitors, then the owner is the stack address of the
4639 // Lock Word in the owning Java thread's stack.
4640 //
4641 JavaThread* the_owner = NULL;
4642 DO_JAVA_THREADS(t_list, q) {
4643 if (q->is_lock_owned(owner)) {
4644 the_owner = q;
4645 break;
4646 }
4647 }
4648
4649 // cannot assert on lack of success here; see above comment
4650 return the_owner;
4651 }
4652
4653 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4654 void Threads::print_on(outputStream* st, bool print_stacks,
4655 bool internal_format, bool print_concurrent_locks,
4656 bool print_extended_info) {
4657 char buf[32];
4658 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4659
4660 st->print_cr("Full thread dump %s (%s %s):",
4661 VM_Version::vm_name(),
4662 VM_Version::vm_release(),
4663 VM_Version::vm_info_string());
4664 st->cr();
4665
4666 #if INCLUDE_SERVICES
4667 // Dump concurrent locks
4668 ConcurrentLocksDump concurrent_locks;
4669 if (print_concurrent_locks) {
4670 concurrent_locks.dump_at_safepoint();
4671 }
4672 #endif // INCLUDE_SERVICES
4673
4674 ThreadsSMRSupport::print_info_on(st);
4675 st->cr();
4676
4677 ALL_JAVA_THREADS(p) {
4678 ResourceMark rm;
4679 p->print_on(st, print_extended_info);
4680 if (print_stacks) {
4681 if (internal_format) {
4682 p->trace_stack();
4683 } else {
4684 p->print_stack_on(st);
4685 }
4686 }
4687 st->cr();
4688 #if INCLUDE_SERVICES
4689 if (print_concurrent_locks) {
4690 concurrent_locks.print_locks_on(p, st);
4691 }
4692 #endif // INCLUDE_SERVICES
4693 }
4694
4695 VMThread::vm_thread()->print_on(st);
4696 st->cr();
4697 Universe::heap()->print_gc_threads_on(st);
4698 WatcherThread* wt = WatcherThread::watcher_thread();
4699 if (wt != NULL) {
4700 wt->print_on(st);
4701 st->cr();
4702 }
4703
4704 st->flush();
4705 }
4706
4707 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4708 int buflen, bool* found_current) {
4709 if (this_thread != NULL) {
4710 bool is_current = (current == this_thread);
4711 *found_current = *found_current || is_current;
4712 st->print("%s", is_current ? "=>" : " ");
4713
4714 st->print(PTR_FORMAT, p2i(this_thread));
4715 st->print(" ");
4716 this_thread->print_on_error(st, buf, buflen);
4717 st->cr();
4718 }
4719 }
4720
4721 class PrintOnErrorClosure : public ThreadClosure {
4722 outputStream* _st;
4723 Thread* _current;
4724 char* _buf;
4725 int _buflen;
4726 bool* _found_current;
4727 public:
4728 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4729 int buflen, bool* found_current) :
4730 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4731
4732 virtual void do_thread(Thread* thread) {
4733 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4734 }
4735 };
4736
4737 // Threads::print_on_error() is called by fatal error handler. It's possible
4738 // that VM is not at safepoint and/or current thread is inside signal handler.
4739 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4740 // memory (even in resource area), it might deadlock the error handler.
4741 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4742 int buflen) {
4743 ThreadsSMRSupport::print_info_on(st);
4744 st->cr();
4745
4746 bool found_current = false;
4747 st->print_cr("Java Threads: ( => current thread )");
4748 ALL_JAVA_THREADS(thread) {
4749 print_on_error(thread, st, current, buf, buflen, &found_current);
4750 }
4751 st->cr();
4752
4753 st->print_cr("Other Threads:");
4754 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4755 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4756
4757 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4758 Universe::heap()->gc_threads_do(&print_closure);
4759
4760 if (!found_current) {
4761 st->cr();
4762 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4763 current->print_on_error(st, buf, buflen);
4764 st->cr();
4765 }
4766 st->cr();
4767
4768 st->print_cr("Threads with active compile tasks:");
4769 print_threads_compiling(st, buf, buflen);
4770 }
4771
4772 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4773 ALL_JAVA_THREADS(thread) {
4774 if (thread->is_Compiler_thread()) {
4775 CompilerThread* ct = (CompilerThread*) thread;
4776
4777 // Keep task in local variable for NULL check.
4778 // ct->_task might be set to NULL by concurring compiler thread
4779 // because it completed the compilation. The task is never freed,
4780 // though, just returned to a free list.
4781 CompileTask* task = ct->task();
4782 if (task != NULL) {
4783 thread->print_name_on_error(st, buf, buflen);
4784 st->print(" ");
4785 task->print(st, NULL, short_form, true);
4786 }
4787 }
4788 }
4789 }
4790
4791
4792 // Internal SpinLock and Mutex
4793 // Based on ParkEvent
4794
4795 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4796 //
4797 // We employ SpinLocks _only for low-contention, fixed-length
4798 // short-duration critical sections where we're concerned
4799 // about native mutex_t or HotSpot Mutex:: latency.
4800 // The mux construct provides a spin-then-block mutual exclusion
4801 // mechanism.
4802 //
4803 // Testing has shown that contention on the ListLock guarding gFreeList
4804 // is common. If we implement ListLock as a simple SpinLock it's common
4805 // for the JVM to devolve to yielding with little progress. This is true
4806 // despite the fact that the critical sections protected by ListLock are
4807 // extremely short.
4808 //
4809 // TODO-FIXME: ListLock should be of type SpinLock.
4810 // We should make this a 1st-class type, integrated into the lock
4811 // hierarchy as leaf-locks. Critically, the SpinLock structure
4812 // should have sufficient padding to avoid false-sharing and excessive
4813 // cache-coherency traffic.
4814
4815
4816 typedef volatile int SpinLockT;
4817
4818 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4819 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4820 return; // normal fast-path return
4821 }
4822
4823 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4824 int ctr = 0;
4825 int Yields = 0;
4826 for (;;) {
4827 while (*adr != 0) {
4828 ++ctr;
4829 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4830 if (Yields > 5) {
4831 os::naked_short_sleep(1);
4832 } else {
4833 os::naked_yield();
4834 ++Yields;
4835 }
4836 } else {
4837 SpinPause();
4838 }
4839 }
4840 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4841 }
4842 }
4843
4844 void Thread::SpinRelease(volatile int * adr) {
4845 assert(*adr != 0, "invariant");
4846 OrderAccess::fence(); // guarantee at least release consistency.
4847 // Roach-motel semantics.
4848 // It's safe if subsequent LDs and STs float "up" into the critical section,
4849 // but prior LDs and STs within the critical section can't be allowed
4850 // to reorder or float past the ST that releases the lock.
4851 // Loads and stores in the critical section - which appear in program
4852 // order before the store that releases the lock - must also appear
4853 // before the store that releases the lock in memory visibility order.
4854 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4855 // the ST of 0 into the lock-word which releases the lock, so fence
4856 // more than covers this on all platforms.
4857 *adr = 0;
4858 }
4859
4860 // muxAcquire and muxRelease:
4861 //
4862 // * muxAcquire and muxRelease support a single-word lock-word construct.
4863 // The LSB of the word is set IFF the lock is held.
4864 // The remainder of the word points to the head of a singly-linked list
4865 // of threads blocked on the lock.
4866 //
4867 // * The current implementation of muxAcquire-muxRelease uses its own
4868 // dedicated Thread._MuxEvent instance. If we're interested in
4869 // minimizing the peak number of extant ParkEvent instances then
4870 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4871 // as certain invariants were satisfied. Specifically, care would need
4872 // to be taken with regards to consuming unpark() "permits".
4873 // A safe rule of thumb is that a thread would never call muxAcquire()
4874 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4875 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4876 // consume an unpark() permit intended for monitorenter, for instance.
4877 // One way around this would be to widen the restricted-range semaphore
4878 // implemented in park(). Another alternative would be to provide
4879 // multiple instances of the PlatformEvent() for each thread. One
4880 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4881 //
4882 // * Usage:
4883 // -- Only as leaf locks
4884 // -- for short-term locking only as muxAcquire does not perform
4885 // thread state transitions.
4886 //
4887 // Alternatives:
4888 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4889 // but with parking or spin-then-park instead of pure spinning.
4890 // * Use Taura-Oyama-Yonenzawa locks.
4891 // * It's possible to construct a 1-0 lock if we encode the lockword as
4892 // (List,LockByte). Acquire will CAS the full lockword while Release
4893 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4894 // acquiring threads use timers (ParkTimed) to detect and recover from
4895 // the stranding window. Thread/Node structures must be aligned on 256-byte
4896 // boundaries by using placement-new.
4897 // * Augment MCS with advisory back-link fields maintained with CAS().
4898 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4899 // The validity of the backlinks must be ratified before we trust the value.
4900 // If the backlinks are invalid the exiting thread must back-track through the
4901 // the forward links, which are always trustworthy.
4902 // * Add a successor indication. The LockWord is currently encoded as
4903 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4904 // to provide the usual futile-wakeup optimization.
4905 // See RTStt for details.
4906 //
4907
4908
4909 const intptr_t LOCKBIT = 1;
4910
4911 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4912 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4913 if (w == 0) return;
4914 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4915 return;
4916 }
4917
4918 ParkEvent * const Self = Thread::current()->_MuxEvent;
4919 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4920 for (;;) {
4921 int its = (os::is_MP() ? 100 : 0) + 1;
4922
4923 // Optional spin phase: spin-then-park strategy
4924 while (--its >= 0) {
4925 w = *Lock;
4926 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4927 return;
4928 }
4929 }
4930
4931 Self->reset();
4932 Self->OnList = intptr_t(Lock);
4933 // The following fence() isn't _strictly necessary as the subsequent
4934 // CAS() both serializes execution and ratifies the fetched *Lock value.
4935 OrderAccess::fence();
4936 for (;;) {
4937 w = *Lock;
4938 if ((w & LOCKBIT) == 0) {
4939 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4940 Self->OnList = 0; // hygiene - allows stronger asserts
4941 return;
4942 }
4943 continue; // Interference -- *Lock changed -- Just retry
4944 }
4945 assert(w & LOCKBIT, "invariant");
4946 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4947 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4948 }
4949
4950 while (Self->OnList != 0) {
4951 Self->park();
4952 }
4953 }
4954 }
4955
4956 // Release() must extract a successor from the list and then wake that thread.
4957 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4958 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4959 // Release() would :
4960 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4961 // (B) Extract a successor from the private list "in-hand"
4962 // (C) attempt to CAS() the residual back into *Lock over null.
4963 // If there were any newly arrived threads and the CAS() would fail.
4964 // In that case Release() would detach the RATs, re-merge the list in-hand
4965 // with the RATs and repeat as needed. Alternately, Release() might
4966 // detach and extract a successor, but then pass the residual list to the wakee.
4967 // The wakee would be responsible for reattaching and remerging before it
4968 // competed for the lock.
4969 //
4970 // Both "pop" and DMR are immune from ABA corruption -- there can be
4971 // multiple concurrent pushers, but only one popper or detacher.
4972 // This implementation pops from the head of the list. This is unfair,
4973 // but tends to provide excellent throughput as hot threads remain hot.
4974 // (We wake recently run threads first).
4975 //
4976 // All paths through muxRelease() will execute a CAS.
4977 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4978 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4979 // executed within the critical section are complete and globally visible before the
4980 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4981 void Thread::muxRelease(volatile intptr_t * Lock) {
4982 for (;;) {
4983 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4984 assert(w & LOCKBIT, "invariant");
4985 if (w == LOCKBIT) return;
4986 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4987 assert(List != NULL, "invariant");
4988 assert(List->OnList == intptr_t(Lock), "invariant");
4989 ParkEvent * const nxt = List->ListNext;
4990 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4991
4992 // The following CAS() releases the lock and pops the head element.
4993 // The CAS() also ratifies the previously fetched lock-word value.
4994 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4995 continue;
4996 }
4997 List->OnList = 0;
4998 OrderAccess::fence();
4999 List->unpark();
5000 return;
5001 }
5002 }
5003
5004
5005 void Threads::verify() {
5006 ALL_JAVA_THREADS(p) {
5007 p->verify();
5008 }
5009 VMThread* thread = VMThread::vm_thread();
5010 if (thread != NULL) thread->verify();
5011 }