1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "aot/aotLoader.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/javaClasses.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/scopeDesc.hpp"
35 #include "compiler/compileBroker.hpp"
36 #include "compiler/compileTask.hpp"
37 #include "gc/shared/barrierSet.hpp"
38 #include "gc/shared/gcId.hpp"
39 #include "gc/shared/gcLocker.inline.hpp"
40 #include "gc/shared/workgroup.hpp"
41 #include "interpreter/interpreter.hpp"
42 #include "interpreter/linkResolver.hpp"
43 #include "interpreter/oopMapCache.hpp"
44 #include "jfr/jfrEvents.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "runtime/arguments.hpp"
65 #include "runtime/atomic.hpp"
66 #include "runtime/biasedLocking.hpp"
67 #include "runtime/fieldDescriptor.inline.hpp"
68 #include "runtime/flags/jvmFlagConstraintList.hpp"
69 #include "runtime/flags/jvmFlagRangeList.hpp"
70 #include "runtime/flags/jvmFlagWriteableList.hpp"
71 #include "runtime/deoptimization.hpp"
72 #include "runtime/frame.inline.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/handshake.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/jniHandles.inline.hpp"
80 #include "runtime/jniPeriodicChecker.hpp"
81 #include "runtime/memprofiler.hpp"
82 #include "runtime/mutexLocker.hpp"
83 #include "runtime/objectMonitor.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/osThread.hpp"
86 #include "runtime/prefetch.inline.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/safepointMechanism.inline.hpp"
89 #include "runtime/safepointVerifiers.hpp"
90 #include "runtime/sharedRuntime.hpp"
91 #include "runtime/statSampler.hpp"
92 #include "runtime/stubRoutines.hpp"
93 #include "runtime/sweeper.hpp"
94 #include "runtime/task.hpp"
95 #include "runtime/thread.inline.hpp"
96 #include "runtime/threadCritical.hpp"
97 #include "runtime/threadSMR.inline.hpp"
98 #include "runtime/threadStatisticalInfo.hpp"
99 #include "runtime/timer.hpp"
100 #include "runtime/timerTrace.hpp"
101 #include "runtime/vframe.inline.hpp"
102 #include "runtime/vframeArray.hpp"
103 #include "runtime/vframe_hp.hpp"
104 #include "runtime/vmThread.hpp"
105 #include "runtime/vmOperations.hpp"
106 #include "runtime/vm_version.hpp"
107 #include "services/attachListener.hpp"
108 #include "services/management.hpp"
109 #include "services/memTracker.hpp"
110 #include "services/threadService.hpp"
111 #include "utilities/align.hpp"
112 #include "utilities/copy.hpp"
113 #include "utilities/defaultStream.hpp"
114 #include "utilities/dtrace.hpp"
115 #include "utilities/events.hpp"
116 #include "utilities/macros.hpp"
117 #include "utilities/preserveException.hpp"
118 #include "utilities/singleWriterSynchronizer.hpp"
119 #include "utilities/vmError.hpp"
120 #if INCLUDE_JVMCI
121 #include "jvmci/jvmci.hpp"
122 #include "jvmci/jvmciEnv.hpp"
123 #endif
124 #ifdef COMPILER1
125 #include "c1/c1_Compiler.hpp"
126 #endif
127 #ifdef COMPILER2
128 #include "opto/c2compiler.hpp"
129 #include "opto/idealGraphPrinter.hpp"
130 #endif
131 #if INCLUDE_RTM_OPT
132 #include "runtime/rtmLocking.hpp"
133 #endif
134 #if INCLUDE_JFR
135 #include "jfr/jfr.hpp"
136 #endif
137
138 // Initialization after module runtime initialization
139 void universe_post_module_init(); // must happen after call_initPhase2
140
141 #ifdef DTRACE_ENABLED
142
143 // Only bother with this argument setup if dtrace is available
144
145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
147
148 #define DTRACE_THREAD_PROBE(probe, javathread) \
149 { \
150 ResourceMark rm(this); \
151 int len = 0; \
152 const char* name = (javathread)->get_thread_name(); \
153 len = strlen(name); \
154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
155 (char *) name, len, \
156 java_lang_Thread::thread_id((javathread)->threadObj()), \
157 (uintptr_t) (javathread)->osthread()->thread_id(), \
158 java_lang_Thread::is_daemon((javathread)->threadObj())); \
159 }
160
161 #else // ndef DTRACE_ENABLED
162
163 #define DTRACE_THREAD_PROBE(probe, javathread)
164
165 #endif // ndef DTRACE_ENABLED
166
167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
168 // Current thread is maintained as a thread-local variable
169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
170 #endif
171
172 // ======= Thread ========
173 // Support for forcing alignment of thread objects for biased locking
174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
175 if (UseBiasedLocking) {
176 const size_t alignment = markWord::biased_lock_alignment;
177 size_t aligned_size = size + (alignment - sizeof(intptr_t));
178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
179 : AllocateHeap(aligned_size, flags, CURRENT_PC,
180 AllocFailStrategy::RETURN_NULL);
181 void* aligned_addr = align_up(real_malloc_addr, alignment);
182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
184 "JavaThread alignment code overflowed allocated storage");
185 if (aligned_addr != real_malloc_addr) {
186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
187 p2i(real_malloc_addr),
188 p2i(aligned_addr));
189 }
190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
191 return aligned_addr;
192 } else {
193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
195 }
196 }
197
198 void Thread::operator delete(void* p) {
199 if (UseBiasedLocking) {
200 FreeHeap(((Thread*) p)->_real_malloc_address);
201 } else {
202 FreeHeap(p);
203 }
204 }
205
206 void JavaThread::smr_delete() {
207 if (_on_thread_list) {
208 ThreadsSMRSupport::smr_delete(this);
209 } else {
210 delete this;
211 }
212 }
213
214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
215 // JavaThread
216
217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
218
219 Thread::Thread() {
220
221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
222
223 // stack and get_thread
224 set_stack_base(NULL);
225 set_stack_size(0);
226 set_lgrp_id(-1);
227 DEBUG_ONLY(clear_suspendible_thread();)
228
229 // allocated data structures
230 set_osthread(NULL);
231 set_resource_area(new (mtThread)ResourceArea());
232 DEBUG_ONLY(_current_resource_mark = NULL;)
233 set_handle_area(new (mtThread) HandleArea(NULL));
234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
235 set_active_handles(NULL);
236 set_free_handle_block(NULL);
237 set_last_handle_mark(NULL);
238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
239
240 // Initial value of zero ==> never claimed.
241 _threads_do_token = 0;
242 _threads_hazard_ptr = NULL;
243 _threads_list_ptr = NULL;
244 _nested_threads_hazard_ptr_cnt = 0;
245 _rcu_counter = 0;
246
247 // the handle mark links itself to last_handle_mark
248 new HandleMark(this);
249
250 // plain initialization
251 debug_only(_owned_locks = NULL;)
252 NOT_PRODUCT(_no_safepoint_count = 0;)
253 NOT_PRODUCT(_skip_gcalot = false;)
254 _jvmti_env_iteration_count = 0;
255 set_allocated_bytes(0);
256 _vm_operation_started_count = 0;
257 _vm_operation_completed_count = 0;
258 _current_pending_monitor = NULL;
259 _current_pending_monitor_is_from_java = true;
260 _current_waiting_monitor = NULL;
261 _num_nested_signal = 0;
262 om_free_list = NULL;
263 om_free_count = 0;
264 om_free_provision = 32;
265 om_in_use_list = NULL;
266 om_in_use_count = 0;
267
268 #ifdef ASSERT
269 _visited_for_critical_count = false;
270 #endif
271
272 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
273 Monitor::_safepoint_check_sometimes);
274 _suspend_flags = 0;
275
276 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
277 _hashStateX = os::random();
278 _hashStateY = 842502087;
279 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
280 _hashStateW = 273326509;
281
282 _OnTrap = 0;
283 _Stalled = 0;
284 _TypeTag = 0x2BAD;
285
286 // Many of the following fields are effectively final - immutable
287 // Note that nascent threads can't use the Native Monitor-Mutex
288 // construct until the _MutexEvent is initialized ...
289 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
290 // we might instead use a stack of ParkEvents that we could provision on-demand.
291 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
292 // and ::Release()
293 _ParkEvent = ParkEvent::Allocate(this);
294 _SleepEvent = 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(_SleepEvent); _SleepEvent = NULL;
460 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
461
462 delete handle_area();
463 delete metadata_handles();
464
465 // SR_handler uses this as a termination indicator -
466 // needs to happen before os::free_thread()
467 delete _SR_lock;
468 _SR_lock = NULL;
469
470 // osthread() can be NULL, if creation of thread failed.
471 if (osthread() != NULL) os::free_thread(osthread());
472
473 // Clear Thread::current if thread is deleting itself and it has not
474 // already been done. This must be done before the memory is deallocated.
475 // Needed to ensure JNI correctly detects non-attached threads.
476 if (this == Thread::current_or_null()) {
477 Thread::clear_thread_current();
478 }
479
480 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
481 }
482
483 #ifdef ASSERT
484 // A JavaThread is considered "dangling" if it is not the current
485 // thread, has been added the Threads list, the system is not at a
486 // safepoint and the Thread is not "protected".
487 //
488 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
489 assert(!thread->is_Java_thread() || Thread::current() == thread ||
490 !((JavaThread *) thread)->on_thread_list() ||
491 SafepointSynchronize::is_at_safepoint() ||
492 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
493 "possibility of dangling Thread pointer");
494 }
495 #endif
496
497 ThreadPriority Thread::get_priority(const Thread* const thread) {
498 ThreadPriority priority;
499 // Can return an error!
500 (void)os::get_priority(thread, priority);
501 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
502 return priority;
503 }
504
505 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
506 debug_only(check_for_dangling_thread_pointer(thread);)
507 // Can return an error!
508 (void)os::set_priority(thread, priority);
509 }
510
511
512 void Thread::start(Thread* thread) {
513 // Start is different from resume in that its safety is guaranteed by context or
514 // being called from a Java method synchronized on the Thread object.
515 if (!DisableStartThread) {
516 if (thread->is_Java_thread()) {
517 // Initialize the thread state to RUNNABLE before starting this thread.
518 // Can not set it after the thread started because we do not know the
519 // exact thread state at that time. It could be in MONITOR_WAIT or
520 // in SLEEPING or some other state.
521 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
522 java_lang_Thread::RUNNABLE);
523 }
524 os::start_thread(thread);
525 }
526 }
527
528 // Enqueue a VM_Operation to do the job for us - sometime later
529 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
530 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
531 VMThread::execute(vm_stop);
532 }
533
534
535 // Check if an external suspend request has completed (or has been
536 // cancelled). Returns true if the thread is externally suspended and
537 // false otherwise.
538 //
539 // The bits parameter returns information about the code path through
540 // the routine. Useful for debugging:
541 //
542 // set in is_ext_suspend_completed():
543 // 0x00000001 - routine was entered
544 // 0x00000010 - routine return false at end
545 // 0x00000100 - thread exited (return false)
546 // 0x00000200 - suspend request cancelled (return false)
547 // 0x00000400 - thread suspended (return true)
548 // 0x00001000 - thread is in a suspend equivalent state (return true)
549 // 0x00002000 - thread is native and walkable (return true)
550 // 0x00004000 - thread is native_trans and walkable (needed retry)
551 //
552 // set in wait_for_ext_suspend_completion():
553 // 0x00010000 - routine was entered
554 // 0x00020000 - suspend request cancelled before loop (return false)
555 // 0x00040000 - thread suspended before loop (return true)
556 // 0x00080000 - suspend request cancelled in loop (return false)
557 // 0x00100000 - thread suspended in loop (return true)
558 // 0x00200000 - suspend not completed during retry loop (return false)
559
560 // Helper class for tracing suspend wait debug bits.
561 //
562 // 0x00000100 indicates that the target thread exited before it could
563 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
564 // 0x00080000 each indicate a cancelled suspend request so they don't
565 // count as wait failures either.
566 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
567
568 class TraceSuspendDebugBits : public StackObj {
569 private:
570 JavaThread * jt;
571 bool is_wait;
572 bool called_by_wait; // meaningful when !is_wait
573 uint32_t * bits;
574
575 public:
576 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
577 uint32_t *_bits) {
578 jt = _jt;
579 is_wait = _is_wait;
580 called_by_wait = _called_by_wait;
581 bits = _bits;
582 }
583
584 ~TraceSuspendDebugBits() {
585 if (!is_wait) {
586 #if 1
587 // By default, don't trace bits for is_ext_suspend_completed() calls.
588 // That trace is very chatty.
589 return;
590 #else
591 if (!called_by_wait) {
592 // If tracing for is_ext_suspend_completed() is enabled, then only
593 // trace calls to it from wait_for_ext_suspend_completion()
594 return;
595 }
596 #endif
597 }
598
599 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
600 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
601 MutexLocker ml(Threads_lock); // needed for get_thread_name()
602 ResourceMark rm;
603
604 tty->print_cr(
605 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
606 jt->get_thread_name(), *bits);
607
608 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
609 }
610 }
611 }
612 };
613 #undef DEBUG_FALSE_BITS
614
615
616 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
617 uint32_t *bits) {
618 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
619
620 bool did_trans_retry = false; // only do thread_in_native_trans retry once
621 bool do_trans_retry; // flag to force the retry
622
623 *bits |= 0x00000001;
624
625 do {
626 do_trans_retry = false;
627
628 if (is_exiting()) {
629 // Thread is in the process of exiting. This is always checked
630 // first to reduce the risk of dereferencing a freed JavaThread.
631 *bits |= 0x00000100;
632 return false;
633 }
634
635 if (!is_external_suspend()) {
636 // Suspend request is cancelled. This is always checked before
637 // is_ext_suspended() to reduce the risk of a rogue resume
638 // confusing the thread that made the suspend request.
639 *bits |= 0x00000200;
640 return false;
641 }
642
643 if (is_ext_suspended()) {
644 // thread is suspended
645 *bits |= 0x00000400;
646 return true;
647 }
648
649 // Now that we no longer do hard suspends of threads running
650 // native code, the target thread can be changing thread state
651 // while we are in this routine:
652 //
653 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
654 //
655 // We save a copy of the thread state as observed at this moment
656 // and make our decision about suspend completeness based on the
657 // copy. This closes the race where the thread state is seen as
658 // _thread_in_native_trans in the if-thread_blocked check, but is
659 // seen as _thread_blocked in if-thread_in_native_trans check.
660 JavaThreadState save_state = thread_state();
661
662 if (save_state == _thread_blocked && is_suspend_equivalent()) {
663 // If the thread's state is _thread_blocked and this blocking
664 // condition is known to be equivalent to a suspend, then we can
665 // consider the thread to be externally suspended. This means that
666 // the code that sets _thread_blocked has been modified to do
667 // self-suspension if the blocking condition releases. We also
668 // used to check for CONDVAR_WAIT here, but that is now covered by
669 // the _thread_blocked with self-suspension check.
670 //
671 // Return true since we wouldn't be here unless there was still an
672 // external suspend request.
673 *bits |= 0x00001000;
674 return true;
675 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
676 // Threads running native code will self-suspend on native==>VM/Java
677 // transitions. If its stack is walkable (should always be the case
678 // unless this function is called before the actual java_suspend()
679 // call), then the wait is done.
680 *bits |= 0x00002000;
681 return true;
682 } else if (!called_by_wait && !did_trans_retry &&
683 save_state == _thread_in_native_trans &&
684 frame_anchor()->walkable()) {
685 // The thread is transitioning from thread_in_native to another
686 // thread state. check_safepoint_and_suspend_for_native_trans()
687 // will force the thread to self-suspend. If it hasn't gotten
688 // there yet we may have caught the thread in-between the native
689 // code check above and the self-suspend. Lucky us. If we were
690 // called by wait_for_ext_suspend_completion(), then it
691 // will be doing the retries so we don't have to.
692 //
693 // Since we use the saved thread state in the if-statement above,
694 // there is a chance that the thread has already transitioned to
695 // _thread_blocked by the time we get here. In that case, we will
696 // make a single unnecessary pass through the logic below. This
697 // doesn't hurt anything since we still do the trans retry.
698
699 *bits |= 0x00004000;
700
701 // Once the thread leaves thread_in_native_trans for another
702 // thread state, we break out of this retry loop. We shouldn't
703 // need this flag to prevent us from getting back here, but
704 // sometimes paranoia is good.
705 did_trans_retry = true;
706
707 // We wait for the thread to transition to a more usable state.
708 for (int i = 1; i <= SuspendRetryCount; i++) {
709 // We used to do an "os::yield_all(i)" call here with the intention
710 // that yielding would increase on each retry. However, the parameter
711 // is ignored on Linux which means the yield didn't scale up. Waiting
712 // on the SR_lock below provides a much more predictable scale up for
713 // the delay. It also provides a simple/direct point to check for any
714 // safepoint requests from the VMThread
715
716 // temporarily drops SR_lock while doing wait with safepoint check
717 // (if we're a JavaThread - the WatcherThread can also call this)
718 // and increase delay with each retry
719 if (Thread::current()->is_Java_thread()) {
720 SR_lock()->wait(i * delay);
721 } else {
722 SR_lock()->wait_without_safepoint_check(i * delay);
723 }
724
725 // check the actual thread state instead of what we saved above
726 if (thread_state() != _thread_in_native_trans) {
727 // the thread has transitioned to another thread state so
728 // try all the checks (except this one) one more time.
729 do_trans_retry = true;
730 break;
731 }
732 } // end retry loop
733
734
735 }
736 } while (do_trans_retry);
737
738 *bits |= 0x00000010;
739 return false;
740 }
741
742 // Wait for an external suspend request to complete (or be cancelled).
743 // Returns true if the thread is externally suspended and false otherwise.
744 //
745 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
746 uint32_t *bits) {
747 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
748 false /* !called_by_wait */, bits);
749
750 // local flag copies to minimize SR_lock hold time
751 bool is_suspended;
752 bool pending;
753 uint32_t reset_bits;
754
755 // set a marker so is_ext_suspend_completed() knows we are the caller
756 *bits |= 0x00010000;
757
758 // We use reset_bits to reinitialize the bits value at the top of
759 // each retry loop. This allows the caller to make use of any
760 // unused bits for their own marking purposes.
761 reset_bits = *bits;
762
763 {
764 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
765 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
766 delay, bits);
767 pending = is_external_suspend();
768 }
769 // must release SR_lock to allow suspension to complete
770
771 if (!pending) {
772 // A cancelled suspend request is the only false return from
773 // is_ext_suspend_completed() that keeps us from entering the
774 // retry loop.
775 *bits |= 0x00020000;
776 return false;
777 }
778
779 if (is_suspended) {
780 *bits |= 0x00040000;
781 return true;
782 }
783
784 for (int i = 1; i <= retries; i++) {
785 *bits = reset_bits; // reinit to only track last retry
786
787 // We used to do an "os::yield_all(i)" call here with the intention
788 // that yielding would increase on each retry. However, the parameter
789 // is ignored on Linux which means the yield didn't scale up. Waiting
790 // on the SR_lock below provides a much more predictable scale up for
791 // the delay. It also provides a simple/direct point to check for any
792 // safepoint requests from the VMThread
793
794 {
795 Thread* t = Thread::current();
796 MonitorLocker ml(SR_lock(),
797 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
798 // wait with safepoint check (if we're a JavaThread - the WatcherThread
799 // can also call this) and increase delay with each retry
800 ml.wait(i * delay);
801
802 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
803 delay, bits);
804
805 // It is possible for the external suspend request to be cancelled
806 // (by a resume) before the actual suspend operation is completed.
807 // Refresh our local copy to see if we still need to wait.
808 pending = is_external_suspend();
809 }
810
811 if (!pending) {
812 // A cancelled suspend request is the only false return from
813 // is_ext_suspend_completed() that keeps us from staying in the
814 // retry loop.
815 *bits |= 0x00080000;
816 return false;
817 }
818
819 if (is_suspended) {
820 *bits |= 0x00100000;
821 return true;
822 }
823 } // end retry loop
824
825 // thread did not suspend after all our retries
826 *bits |= 0x00200000;
827 return false;
828 }
829
830 // Called from API entry points which perform stack walking. If the
831 // associated JavaThread is the current thread, then wait_for_suspend
832 // is not used. Otherwise, it determines if we should wait for the
833 // "other" thread to complete external suspension. (NOTE: in future
834 // releases the suspension mechanism should be reimplemented so this
835 // is not necessary.)
836 //
837 bool
838 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
839 if (this != JavaThread::current()) {
840 // "other" threads require special handling.
841 if (wait_for_suspend) {
842 // We are allowed to wait for the external suspend to complete
843 // so give the other thread a chance to get suspended.
844 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
845 SuspendRetryDelay, bits)) {
846 // Didn't make it so let the caller know.
847 return false;
848 }
849 }
850 // We aren't allowed to wait for the external suspend to complete
851 // so if the other thread isn't externally suspended we need to
852 // let the caller know.
853 else if (!is_ext_suspend_completed_with_lock(bits)) {
854 return false;
855 }
856 }
857
858 return true;
859 }
860
861 void Thread::interrupt(Thread* thread) {
862 debug_only(check_for_dangling_thread_pointer(thread);)
863 os::interrupt(thread);
864 }
865
866 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
867 debug_only(check_for_dangling_thread_pointer(thread);)
868 // Note: If clear_interrupted==false, this simply fetches and
869 // returns the value of the field osthread()->interrupted().
870 return os::is_interrupted(thread, clear_interrupted);
871 }
872
873
874 // GC Support
875 bool Thread::claim_par_threads_do(uintx claim_token) {
876 uintx token = _threads_do_token;
877 if (token != claim_token) {
878 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
879 if (res == token) {
880 return true;
881 }
882 guarantee(res == claim_token, "invariant");
883 }
884 return false;
885 }
886
887 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
888 active_handles()->oops_do(f);
889 // Do oop for ThreadShadow
890 f->do_oop((oop*)&_pending_exception);
891 handle_area()->oops_do(f);
892
893 // We scan thread local monitor lists here, and the remaining global
894 // monitors in ObjectSynchronizer::oops_do().
895 ObjectSynchronizer::thread_local_used_oops_do(this, f);
896 }
897
898 void Thread::metadata_handles_do(void f(Metadata*)) {
899 // Only walk the Handles in Thread.
900 if (metadata_handles() != NULL) {
901 for (int i = 0; i< metadata_handles()->length(); i++) {
902 f(metadata_handles()->at(i));
903 }
904 }
905 }
906
907 void Thread::print_on(outputStream* st, bool print_extended_info) const {
908 // get_priority assumes osthread initialized
909 if (osthread() != NULL) {
910 int os_prio;
911 if (os::get_native_priority(this, &os_prio) == OS_OK) {
912 st->print("os_prio=%d ", os_prio);
913 }
914
915 st->print("cpu=%.2fms ",
916 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
917 );
918 st->print("elapsed=%.2fs ",
919 _statistical_info.getElapsedTime() / 1000.0
920 );
921 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
922 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
923 st->print("allocated=" SIZE_FORMAT "%s ",
924 byte_size_in_proper_unit(allocated_bytes),
925 proper_unit_for_byte_size(allocated_bytes)
926 );
927 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
928 }
929
930 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
931 osthread()->print_on(st);
932 }
933 ThreadsSMRSupport::print_info_on(this, st);
934 st->print(" ");
935 debug_only(if (WizardMode) print_owned_locks_on(st);)
936 }
937
938 void Thread::print() const { print_on(tty); }
939
940 // Thread::print_on_error() is called by fatal error handler. Don't use
941 // any lock or allocate memory.
942 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
943 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
944
945 if (is_VM_thread()) { st->print("VMThread"); }
946 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
947 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
948 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
949 else { st->print("Thread"); }
950
951 if (is_Named_thread()) {
952 st->print(" \"%s\"", name());
953 }
954
955 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
956 p2i(stack_end()), p2i(stack_base()));
957
958 if (osthread()) {
959 st->print(" [id=%d]", osthread()->thread_id());
960 }
961
962 ThreadsSMRSupport::print_info_on(this, st);
963 }
964
965 void Thread::print_value_on(outputStream* st) const {
966 if (is_Named_thread()) {
967 st->print(" \"%s\" ", name());
968 }
969 st->print(INTPTR_FORMAT, p2i(this)); // print address
970 }
971
972 #ifdef ASSERT
973 void Thread::print_owned_locks_on(outputStream* st) const {
974 Mutex* cur = _owned_locks;
975 if (cur == NULL) {
976 st->print(" (no locks) ");
977 } else {
978 st->print_cr(" Locks owned:");
979 while (cur) {
980 cur->print_on(st);
981 cur = cur->next();
982 }
983 }
984 }
985
986 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
987 void Thread::check_possible_safepoint() {
988 if (!is_Java_thread()) return;
989
990 if (_no_safepoint_count > 0) {
991 fatal("Possible safepoint reached by thread that does not allow it");
992 }
993 #ifdef CHECK_UNHANDLED_OOPS
994 // Clear unhandled oops in JavaThreads so we get a crash right away.
995 clear_unhandled_oops();
996 #endif // CHECK_UNHANDLED_OOPS
997 }
998
999 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1000 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1001 // no locks which allow_vm_block's are held
1002 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1003 if (!is_Java_thread()) return;
1004
1005 check_possible_safepoint();
1006
1007 if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1008 fatal("LEAF method calling lock?");
1009 }
1010
1011 if (potential_vm_operation && !Universe::is_bootstrapping()) {
1012 // Make sure we do not hold any locks that the VM thread also uses.
1013 // This could potentially lead to deadlocks
1014 for (Mutex* cur = _owned_locks; cur; cur = cur->next()) {
1015 // Threads_lock is special, since the safepoint synchronization will not start before this is
1016 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1017 // since it is used to transfer control between JavaThreads and the VMThread
1018 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1019 if ((cur->allow_vm_block() &&
1020 cur != Threads_lock &&
1021 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1022 cur != VMOperationRequest_lock &&
1023 cur != VMOperationQueue_lock) ||
1024 cur->rank() == Mutex::special) {
1025 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1026 }
1027 }
1028 }
1029
1030 if (GCALotAtAllSafepoints) {
1031 // We could enter a safepoint here and thus have a gc
1032 InterfaceSupport::check_gc_alot();
1033 }
1034 }
1035 #endif // ASSERT
1036
1037 bool Thread::is_in_stack(address adr) const {
1038 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1039 address end = os::current_stack_pointer();
1040 // Allow non Java threads to call this without stack_base
1041 if (_stack_base == NULL) return true;
1042 if (stack_base() >= adr && adr >= end) return true;
1043
1044 return false;
1045 }
1046
1047 bool Thread::is_in_usable_stack(address adr) const {
1048 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1049 size_t usable_stack_size = _stack_size - stack_guard_size;
1050
1051 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1052 }
1053
1054
1055 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1056 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1057 // used for compilation in the future. If that change is made, the need for these methods
1058 // should be revisited, and they should be removed if possible.
1059
1060 bool Thread::is_lock_owned(address adr) const {
1061 return on_local_stack(adr);
1062 }
1063
1064 bool Thread::set_as_starting_thread() {
1065 assert(_starting_thread == NULL, "already initialized: "
1066 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1067 // NOTE: this must be called inside the main thread.
1068 DEBUG_ONLY(_starting_thread = this;)
1069 return os::create_main_thread((JavaThread*)this);
1070 }
1071
1072 static void initialize_class(Symbol* class_name, TRAPS) {
1073 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1074 InstanceKlass::cast(klass)->initialize(CHECK);
1075 }
1076
1077
1078 // Creates the initial ThreadGroup
1079 static Handle create_initial_thread_group(TRAPS) {
1080 Handle system_instance = JavaCalls::construct_new_instance(
1081 SystemDictionary::ThreadGroup_klass(),
1082 vmSymbols::void_method_signature(),
1083 CHECK_NH);
1084 Universe::set_system_thread_group(system_instance());
1085
1086 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1087 Handle main_instance = JavaCalls::construct_new_instance(
1088 SystemDictionary::ThreadGroup_klass(),
1089 vmSymbols::threadgroup_string_void_signature(),
1090 system_instance,
1091 string,
1092 CHECK_NH);
1093 return main_instance;
1094 }
1095
1096 // Creates the initial Thread
1097 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1098 TRAPS) {
1099 InstanceKlass* ik = SystemDictionary::Thread_klass();
1100 assert(ik->is_initialized(), "must be");
1101 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1102
1103 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1104 // constructor calls Thread.current(), which must be set here for the
1105 // initial thread.
1106 java_lang_Thread::set_thread(thread_oop(), thread);
1107 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1108 thread->set_threadObj(thread_oop());
1109
1110 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1111
1112 JavaValue result(T_VOID);
1113 JavaCalls::call_special(&result, thread_oop,
1114 ik,
1115 vmSymbols::object_initializer_name(),
1116 vmSymbols::threadgroup_string_void_signature(),
1117 thread_group,
1118 string,
1119 CHECK_NULL);
1120 return thread_oop();
1121 }
1122
1123 char java_runtime_name[128] = "";
1124 char java_runtime_version[128] = "";
1125
1126 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1127 static const char* get_java_runtime_name(TRAPS) {
1128 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1129 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1130 fieldDescriptor fd;
1131 bool found = k != NULL &&
1132 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1133 vmSymbols::string_signature(), &fd);
1134 if (found) {
1135 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1136 if (name_oop == NULL) {
1137 return NULL;
1138 }
1139 const char* name = java_lang_String::as_utf8_string(name_oop,
1140 java_runtime_name,
1141 sizeof(java_runtime_name));
1142 return name;
1143 } else {
1144 return NULL;
1145 }
1146 }
1147
1148 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1149 static const char* get_java_runtime_version(TRAPS) {
1150 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1151 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1152 fieldDescriptor fd;
1153 bool found = k != NULL &&
1154 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1155 vmSymbols::string_signature(), &fd);
1156 if (found) {
1157 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1158 if (name_oop == NULL) {
1159 return NULL;
1160 }
1161 const char* name = java_lang_String::as_utf8_string(name_oop,
1162 java_runtime_version,
1163 sizeof(java_runtime_version));
1164 return name;
1165 } else {
1166 return NULL;
1167 }
1168 }
1169
1170 // General purpose hook into Java code, run once when the VM is initialized.
1171 // The Java library method itself may be changed independently from the VM.
1172 static void call_postVMInitHook(TRAPS) {
1173 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1174 if (klass != NULL) {
1175 JavaValue result(T_VOID);
1176 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1177 vmSymbols::void_method_signature(),
1178 CHECK);
1179 }
1180 }
1181
1182 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1183 bool daemon, TRAPS) {
1184 assert(thread_group.not_null(), "thread group should be specified");
1185 assert(threadObj() == NULL, "should only create Java thread object once");
1186
1187 InstanceKlass* ik = SystemDictionary::Thread_klass();
1188 assert(ik->is_initialized(), "must be");
1189 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1190
1191 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1192 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1193 // constructor calls Thread.current(), which must be set here.
1194 java_lang_Thread::set_thread(thread_oop(), this);
1195 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1196 set_threadObj(thread_oop());
1197
1198 JavaValue result(T_VOID);
1199 if (thread_name != NULL) {
1200 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1201 // Thread gets assigned specified name and null target
1202 JavaCalls::call_special(&result,
1203 thread_oop,
1204 ik,
1205 vmSymbols::object_initializer_name(),
1206 vmSymbols::threadgroup_string_void_signature(),
1207 thread_group,
1208 name,
1209 THREAD);
1210 } else {
1211 // Thread gets assigned name "Thread-nnn" and null target
1212 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1213 JavaCalls::call_special(&result,
1214 thread_oop,
1215 ik,
1216 vmSymbols::object_initializer_name(),
1217 vmSymbols::threadgroup_runnable_void_signature(),
1218 thread_group,
1219 Handle(),
1220 THREAD);
1221 }
1222
1223
1224 if (daemon) {
1225 java_lang_Thread::set_daemon(thread_oop());
1226 }
1227
1228 if (HAS_PENDING_EXCEPTION) {
1229 return;
1230 }
1231
1232 Klass* group = SystemDictionary::ThreadGroup_klass();
1233 Handle threadObj(THREAD, this->threadObj());
1234
1235 JavaCalls::call_special(&result,
1236 thread_group,
1237 group,
1238 vmSymbols::add_method_name(),
1239 vmSymbols::thread_void_signature(),
1240 threadObj, // Arg 1
1241 THREAD);
1242 }
1243
1244 // List of all NonJavaThreads and safe iteration over that list.
1245
1246 class NonJavaThread::List {
1247 public:
1248 NonJavaThread* volatile _head;
1249 SingleWriterSynchronizer _protect;
1250
1251 List() : _head(NULL), _protect() {}
1252 };
1253
1254 NonJavaThread::List NonJavaThread::_the_list;
1255
1256 NonJavaThread::Iterator::Iterator() :
1257 _protect_enter(_the_list._protect.enter()),
1258 _current(OrderAccess::load_acquire(&_the_list._head))
1259 {}
1260
1261 NonJavaThread::Iterator::~Iterator() {
1262 _the_list._protect.exit(_protect_enter);
1263 }
1264
1265 void NonJavaThread::Iterator::step() {
1266 assert(!end(), "precondition");
1267 _current = OrderAccess::load_acquire(&_current->_next);
1268 }
1269
1270 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1271 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1272 }
1273
1274 NonJavaThread::~NonJavaThread() { }
1275
1276 void NonJavaThread::add_to_the_list() {
1277 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1278 // Initialize BarrierSet-related data before adding to list.
1279 BarrierSet::barrier_set()->on_thread_attach(this);
1280 OrderAccess::release_store(&_next, _the_list._head);
1281 OrderAccess::release_store(&_the_list._head, this);
1282 }
1283
1284 void NonJavaThread::remove_from_the_list() {
1285 {
1286 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1287 // Cleanup BarrierSet-related data before removing from list.
1288 BarrierSet::barrier_set()->on_thread_detach(this);
1289 NonJavaThread* volatile* p = &_the_list._head;
1290 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1291 if (t == this) {
1292 *p = _next;
1293 break;
1294 }
1295 }
1296 }
1297 // Wait for any in-progress iterators. Concurrent synchronize is not
1298 // allowed, so do it while holding a dedicated lock. Outside and distinct
1299 // from NJTList_lock in case an iteration attempts to lock it.
1300 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1301 _the_list._protect.synchronize();
1302 _next = NULL; // Safe to drop the link now.
1303 }
1304
1305 void NonJavaThread::pre_run() {
1306 add_to_the_list();
1307
1308 // This is slightly odd in that NamedThread is a subclass, but
1309 // in fact name() is defined in Thread
1310 assert(this->name() != NULL, "thread name was not set before it was started");
1311 this->set_native_thread_name(this->name());
1312 }
1313
1314 void NonJavaThread::post_run() {
1315 JFR_ONLY(Jfr::on_thread_exit(this);)
1316 remove_from_the_list();
1317 // Ensure thread-local-storage is cleared before termination.
1318 Thread::clear_thread_current();
1319 }
1320
1321 // NamedThread -- non-JavaThread subclasses with multiple
1322 // uniquely named instances should derive from this.
1323 NamedThread::NamedThread() :
1324 NonJavaThread(),
1325 _name(NULL),
1326 _processed_thread(NULL),
1327 _gc_id(GCId::undefined())
1328 {}
1329
1330 NamedThread::~NamedThread() {
1331 FREE_C_HEAP_ARRAY(char, _name);
1332 }
1333
1334 void NamedThread::set_name(const char* format, ...) {
1335 guarantee(_name == NULL, "Only get to set name once.");
1336 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1337 va_list ap;
1338 va_start(ap, format);
1339 jio_vsnprintf(_name, max_name_len, format, ap);
1340 va_end(ap);
1341 }
1342
1343 void NamedThread::print_on(outputStream* st) const {
1344 st->print("\"%s\" ", name());
1345 Thread::print_on(st);
1346 st->cr();
1347 }
1348
1349
1350 // ======= WatcherThread ========
1351
1352 // The watcher thread exists to simulate timer interrupts. It should
1353 // be replaced by an abstraction over whatever native support for
1354 // timer interrupts exists on the platform.
1355
1356 WatcherThread* WatcherThread::_watcher_thread = NULL;
1357 bool WatcherThread::_startable = false;
1358 volatile bool WatcherThread::_should_terminate = false;
1359
1360 WatcherThread::WatcherThread() : NonJavaThread() {
1361 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1362 if (os::create_thread(this, os::watcher_thread)) {
1363 _watcher_thread = this;
1364
1365 // Set the watcher thread to the highest OS priority which should not be
1366 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1367 // is created. The only normal thread using this priority is the reference
1368 // handler thread, which runs for very short intervals only.
1369 // If the VMThread's priority is not lower than the WatcherThread profiling
1370 // will be inaccurate.
1371 os::set_priority(this, MaxPriority);
1372 if (!DisableStartThread) {
1373 os::start_thread(this);
1374 }
1375 }
1376 }
1377
1378 int WatcherThread::sleep() const {
1379 // The WatcherThread does not participate in the safepoint protocol
1380 // for the PeriodicTask_lock because it is not a JavaThread.
1381 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1382
1383 if (_should_terminate) {
1384 // check for termination before we do any housekeeping or wait
1385 return 0; // we did not sleep.
1386 }
1387
1388 // remaining will be zero if there are no tasks,
1389 // causing the WatcherThread to sleep until a task is
1390 // enrolled
1391 int remaining = PeriodicTask::time_to_wait();
1392 int time_slept = 0;
1393
1394 // we expect this to timeout - we only ever get unparked when
1395 // we should terminate or when a new task has been enrolled
1396 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1397
1398 jlong time_before_loop = os::javaTimeNanos();
1399
1400 while (true) {
1401 bool timedout = ml.wait(remaining);
1402 jlong now = os::javaTimeNanos();
1403
1404 if (remaining == 0) {
1405 // if we didn't have any tasks we could have waited for a long time
1406 // consider the time_slept zero and reset time_before_loop
1407 time_slept = 0;
1408 time_before_loop = now;
1409 } else {
1410 // need to recalculate since we might have new tasks in _tasks
1411 time_slept = (int) ((now - time_before_loop) / 1000000);
1412 }
1413
1414 // Change to task list or spurious wakeup of some kind
1415 if (timedout || _should_terminate) {
1416 break;
1417 }
1418
1419 remaining = PeriodicTask::time_to_wait();
1420 if (remaining == 0) {
1421 // Last task was just disenrolled so loop around and wait until
1422 // another task gets enrolled
1423 continue;
1424 }
1425
1426 remaining -= time_slept;
1427 if (remaining <= 0) {
1428 break;
1429 }
1430 }
1431
1432 return time_slept;
1433 }
1434
1435 void WatcherThread::run() {
1436 assert(this == watcher_thread(), "just checking");
1437
1438 this->set_active_handles(JNIHandleBlock::allocate_block());
1439 while (true) {
1440 assert(watcher_thread() == Thread::current(), "thread consistency check");
1441 assert(watcher_thread() == this, "thread consistency check");
1442
1443 // Calculate how long it'll be until the next PeriodicTask work
1444 // should be done, and sleep that amount of time.
1445 int time_waited = sleep();
1446
1447 if (VMError::is_error_reported()) {
1448 // A fatal error has happened, the error handler(VMError::report_and_die)
1449 // should abort JVM after creating an error log file. However in some
1450 // rare cases, the error handler itself might deadlock. Here periodically
1451 // check for error reporting timeouts, and if it happens, just proceed to
1452 // abort the VM.
1453
1454 // This code is in WatcherThread because WatcherThread wakes up
1455 // periodically so the fatal error handler doesn't need to do anything;
1456 // also because the WatcherThread is less likely to crash than other
1457 // threads.
1458
1459 for (;;) {
1460 // Note: we use naked sleep in this loop because we want to avoid using
1461 // any kind of VM infrastructure which may be broken at this point.
1462 if (VMError::check_timeout()) {
1463 // We hit error reporting timeout. Error reporting was interrupted and
1464 // will be wrapping things up now (closing files etc). Give it some more
1465 // time, then quit the VM.
1466 os::naked_short_sleep(200);
1467 // Print a message to stderr.
1468 fdStream err(defaultStream::output_fd());
1469 err.print_raw_cr("# [ timer expired, abort... ]");
1470 // skip atexit/vm_exit/vm_abort hooks
1471 os::die();
1472 }
1473
1474 // Wait a second, then recheck for timeout.
1475 os::naked_short_sleep(999);
1476 }
1477 }
1478
1479 if (_should_terminate) {
1480 // check for termination before posting the next tick
1481 break;
1482 }
1483
1484 PeriodicTask::real_time_tick(time_waited);
1485 }
1486
1487 // Signal that it is terminated
1488 {
1489 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1490 _watcher_thread = NULL;
1491 Terminator_lock->notify_all();
1492 }
1493 }
1494
1495 void WatcherThread::start() {
1496 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1497
1498 if (watcher_thread() == NULL && _startable) {
1499 _should_terminate = false;
1500 // Create the single instance of WatcherThread
1501 new WatcherThread();
1502 }
1503 }
1504
1505 void WatcherThread::make_startable() {
1506 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1507 _startable = true;
1508 }
1509
1510 void WatcherThread::stop() {
1511 {
1512 // Follow normal safepoint aware lock enter protocol since the
1513 // WatcherThread is stopped by another JavaThread.
1514 MutexLocker ml(PeriodicTask_lock);
1515 _should_terminate = true;
1516
1517 WatcherThread* watcher = watcher_thread();
1518 if (watcher != NULL) {
1519 // unpark the WatcherThread so it can see that it should terminate
1520 watcher->unpark();
1521 }
1522 }
1523
1524 MonitorLocker mu(Terminator_lock);
1525
1526 while (watcher_thread() != NULL) {
1527 // This wait should make safepoint checks, wait without a timeout,
1528 // and wait as a suspend-equivalent condition.
1529 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1530 }
1531 }
1532
1533 void WatcherThread::unpark() {
1534 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1535 PeriodicTask_lock->notify();
1536 }
1537
1538 void WatcherThread::print_on(outputStream* st) const {
1539 st->print("\"%s\" ", name());
1540 Thread::print_on(st);
1541 st->cr();
1542 }
1543
1544 // ======= JavaThread ========
1545
1546 #if INCLUDE_JVMCI
1547
1548 jlong* JavaThread::_jvmci_old_thread_counters;
1549
1550 bool jvmci_counters_include(JavaThread* thread) {
1551 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1552 }
1553
1554 void JavaThread::collect_counters(jlong* array, int length) {
1555 assert(length == JVMCICounterSize, "wrong value");
1556 for (int i = 0; i < length; i++) {
1557 array[i] = _jvmci_old_thread_counters[i];
1558 }
1559 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1560 if (jvmci_counters_include(tp)) {
1561 for (int i = 0; i < length; i++) {
1562 array[i] += tp->_jvmci_counters[i];
1563 }
1564 }
1565 }
1566 }
1567
1568 // Attempt to enlarge the array for per thread counters.
1569 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1570 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1571 if (new_counters == NULL) {
1572 return NULL;
1573 }
1574 if (old_counters == NULL) {
1575 old_counters = new_counters;
1576 memset(old_counters, 0, sizeof(jlong) * new_size);
1577 } else {
1578 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1579 new_counters[i] = old_counters[i];
1580 }
1581 if (new_size > current_size) {
1582 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1583 }
1584 FREE_C_HEAP_ARRAY(jlong, old_counters);
1585 }
1586 return new_counters;
1587 }
1588
1589 // Attempt to enlarge the array for per thread counters.
1590 bool JavaThread::resize_counters(int current_size, int new_size) {
1591 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1592 if (new_counters == NULL) {
1593 return false;
1594 } else {
1595 _jvmci_counters = new_counters;
1596 return true;
1597 }
1598 }
1599
1600 class VM_JVMCIResizeCounters : public VM_Operation {
1601 private:
1602 int _new_size;
1603 bool _failed;
1604
1605 public:
1606 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1607 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1608 bool allow_nested_vm_operations() const { return true; }
1609 void doit() {
1610 // Resize the old thread counters array
1611 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1612 if (new_counters == NULL) {
1613 _failed = true;
1614 return;
1615 } else {
1616 JavaThread::_jvmci_old_thread_counters = new_counters;
1617 }
1618
1619 // Now resize each threads array
1620 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1621 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1622 _failed = true;
1623 break;
1624 }
1625 }
1626 if (!_failed) {
1627 JVMCICounterSize = _new_size;
1628 }
1629 }
1630
1631 bool failed() { return _failed; }
1632 };
1633
1634 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1635 VM_JVMCIResizeCounters op(new_size);
1636 VMThread::execute(&op);
1637 return !op.failed();
1638 }
1639
1640 #endif // INCLUDE_JVMCI
1641
1642 // A JavaThread is a normal Java thread
1643
1644 void JavaThread::initialize() {
1645 // Initialize fields
1646
1647 set_saved_exception_pc(NULL);
1648 set_threadObj(NULL);
1649 _anchor.clear();
1650 set_entry_point(NULL);
1651 set_jni_functions(jni_functions());
1652 set_callee_target(NULL);
1653 set_vm_result(NULL);
1654 set_vm_result_2(NULL);
1655 set_vframe_array_head(NULL);
1656 set_vframe_array_last(NULL);
1657 set_deferred_locals(NULL);
1658 set_deopt_mark(NULL);
1659 set_deopt_compiled_method(NULL);
1660 set_monitor_chunks(NULL);
1661 _on_thread_list = false;
1662 set_thread_state(_thread_new);
1663 _terminated = _not_terminated;
1664 _array_for_gc = NULL;
1665 _suspend_equivalent = false;
1666 _in_deopt_handler = 0;
1667 _doing_unsafe_access = false;
1668 _stack_guard_state = stack_guard_unused;
1669 #if INCLUDE_JVMCI
1670 _pending_monitorenter = false;
1671 _pending_deoptimization = -1;
1672 _pending_failed_speculation = 0;
1673 _pending_transfer_to_interpreter = false;
1674 _in_retryable_allocation = false;
1675 _jvmci._alternate_call_target = NULL;
1676 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1677 _jvmci_counters = NULL;
1678 if (JVMCICounterSize > 0) {
1679 resize_counters(0, (int) JVMCICounterSize);
1680 }
1681 #endif // INCLUDE_JVMCI
1682 _reserved_stack_activation = NULL; // stack base not known yet
1683 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1684 _exception_pc = 0;
1685 _exception_handler_pc = 0;
1686 _is_method_handle_return = 0;
1687 _jvmti_thread_state= NULL;
1688 _should_post_on_exceptions_flag = JNI_FALSE;
1689 _interp_only_mode = 0;
1690 _special_runtime_exit_condition = _no_async_condition;
1691 _pending_async_exception = NULL;
1692 _thread_stat = NULL;
1693 _thread_stat = new ThreadStatistics();
1694 _jni_active_critical = 0;
1695 _pending_jni_exception_check_fn = NULL;
1696 _do_not_unlock_if_synchronized = false;
1697 _cached_monitor_info = NULL;
1698 _parker = Parker::Allocate(this);
1699
1700 // Setup safepoint state info for this thread
1701 ThreadSafepointState::create(this);
1702
1703 debug_only(_java_call_counter = 0);
1704
1705 // JVMTI PopFrame support
1706 _popframe_condition = popframe_inactive;
1707 _popframe_preserved_args = NULL;
1708 _popframe_preserved_args_size = 0;
1709 _frames_to_pop_failed_realloc = 0;
1710
1711 if (SafepointMechanism::uses_thread_local_poll()) {
1712 SafepointMechanism::initialize_header(this);
1713 }
1714
1715 _class_to_be_initialized = NULL;
1716
1717 pd_initialize();
1718 }
1719
1720 JavaThread::JavaThread(bool is_attaching_via_jni) :
1721 Thread() {
1722 initialize();
1723 if (is_attaching_via_jni) {
1724 _jni_attach_state = _attaching_via_jni;
1725 } else {
1726 _jni_attach_state = _not_attaching_via_jni;
1727 }
1728 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1729 }
1730
1731 bool JavaThread::reguard_stack(address cur_sp) {
1732 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1733 && _stack_guard_state != stack_guard_reserved_disabled) {
1734 return true; // Stack already guarded or guard pages not needed.
1735 }
1736
1737 if (register_stack_overflow()) {
1738 // For those architectures which have separate register and
1739 // memory stacks, we must check the register stack to see if
1740 // it has overflowed.
1741 return false;
1742 }
1743
1744 // Java code never executes within the yellow zone: the latter is only
1745 // there to provoke an exception during stack banging. If java code
1746 // is executing there, either StackShadowPages should be larger, or
1747 // some exception code in c1, c2 or the interpreter isn't unwinding
1748 // when it should.
1749 guarantee(cur_sp > stack_reserved_zone_base(),
1750 "not enough space to reguard - increase StackShadowPages");
1751 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1752 enable_stack_yellow_reserved_zone();
1753 if (reserved_stack_activation() != stack_base()) {
1754 set_reserved_stack_activation(stack_base());
1755 }
1756 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1757 set_reserved_stack_activation(stack_base());
1758 enable_stack_reserved_zone();
1759 }
1760 return true;
1761 }
1762
1763 bool JavaThread::reguard_stack(void) {
1764 return reguard_stack(os::current_stack_pointer());
1765 }
1766
1767
1768 void JavaThread::block_if_vm_exited() {
1769 if (_terminated == _vm_exited) {
1770 // _vm_exited is set at safepoint, and Threads_lock is never released
1771 // we will block here forever
1772 Threads_lock->lock();
1773 ShouldNotReachHere();
1774 }
1775 }
1776
1777
1778 // Remove this ifdef when C1 is ported to the compiler interface.
1779 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1780 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1781
1782 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1783 Thread() {
1784 initialize();
1785 _jni_attach_state = _not_attaching_via_jni;
1786 set_entry_point(entry_point);
1787 // Create the native thread itself.
1788 // %note runtime_23
1789 os::ThreadType thr_type = os::java_thread;
1790 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1791 os::java_thread;
1792 os::create_thread(this, thr_type, stack_sz);
1793 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1794 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1795 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1796 // the exception consists of creating the exception object & initializing it, initialization
1797 // will leave the VM via a JavaCall and then all locks must be unlocked).
1798 //
1799 // The thread is still suspended when we reach here. Thread must be explicit started
1800 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1801 // by calling Threads:add. The reason why this is not done here, is because the thread
1802 // object must be fully initialized (take a look at JVM_Start)
1803 }
1804
1805 JavaThread::~JavaThread() {
1806
1807 // JSR166 -- return the parker to the free list
1808 Parker::Release(_parker);
1809 _parker = NULL;
1810
1811 // Free any remaining previous UnrollBlock
1812 vframeArray* old_array = vframe_array_last();
1813
1814 if (old_array != NULL) {
1815 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1816 old_array->set_unroll_block(NULL);
1817 delete old_info;
1818 delete old_array;
1819 }
1820
1821 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1822 if (deferred != NULL) {
1823 // This can only happen if thread is destroyed before deoptimization occurs.
1824 assert(deferred->length() != 0, "empty array!");
1825 do {
1826 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1827 deferred->remove_at(0);
1828 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1829 delete dlv;
1830 } while (deferred->length() != 0);
1831 delete deferred;
1832 }
1833
1834 // All Java related clean up happens in exit
1835 ThreadSafepointState::destroy(this);
1836 if (_thread_stat != NULL) delete _thread_stat;
1837
1838 #if INCLUDE_JVMCI
1839 if (JVMCICounterSize > 0) {
1840 if (jvmci_counters_include(this)) {
1841 for (int i = 0; i < JVMCICounterSize; i++) {
1842 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1843 }
1844 }
1845 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1846 }
1847 #endif // INCLUDE_JVMCI
1848 }
1849
1850
1851 // First JavaThread specific code executed by a new Java thread.
1852 void JavaThread::pre_run() {
1853 // empty - see comments in run()
1854 }
1855
1856 // The main routine called by a new Java thread. This isn't overridden
1857 // by subclasses, instead different subclasses define a different "entry_point"
1858 // which defines the actual logic for that kind of thread.
1859 void JavaThread::run() {
1860 // initialize thread-local alloc buffer related fields
1861 this->initialize_tlab();
1862
1863 // Used to test validity of stack trace backs.
1864 // This can't be moved into pre_run() else we invalidate
1865 // the requirement that thread_main_inner is lower on
1866 // the stack. Consequently all the initialization logic
1867 // stays here in run() rather than pre_run().
1868 this->record_base_of_stack_pointer();
1869
1870 this->create_stack_guard_pages();
1871
1872 this->cache_global_variables();
1873
1874 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1875 // in the VM. Change thread state from _thread_new to _thread_in_vm
1876 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1877 // Before a thread is on the threads list it is always safe, so after leaving the
1878 // _thread_new we should emit a instruction barrier. The distance to modified code
1879 // from here is probably far enough, but this is consistent and safe.
1880 OrderAccess::cross_modify_fence();
1881
1882 assert(JavaThread::current() == this, "sanity check");
1883 assert(!Thread::current()->owns_locks(), "sanity check");
1884
1885 DTRACE_THREAD_PROBE(start, this);
1886
1887 // This operation might block. We call that after all safepoint checks for a new thread has
1888 // been completed.
1889 this->set_active_handles(JNIHandleBlock::allocate_block());
1890
1891 if (JvmtiExport::should_post_thread_life()) {
1892 JvmtiExport::post_thread_start(this);
1893
1894 }
1895
1896 // We call another function to do the rest so we are sure that the stack addresses used
1897 // from there will be lower than the stack base just computed.
1898 thread_main_inner();
1899 }
1900
1901 void JavaThread::thread_main_inner() {
1902 assert(JavaThread::current() == this, "sanity check");
1903 assert(this->threadObj() != NULL, "just checking");
1904
1905 // Execute thread entry point unless this thread has a pending exception
1906 // or has been stopped before starting.
1907 // Note: Due to JVM_StopThread we can have pending exceptions already!
1908 if (!this->has_pending_exception() &&
1909 !java_lang_Thread::is_stillborn(this->threadObj())) {
1910 {
1911 ResourceMark rm(this);
1912 this->set_native_thread_name(this->get_thread_name());
1913 }
1914 HandleMark hm(this);
1915 this->entry_point()(this, this);
1916 }
1917
1918 DTRACE_THREAD_PROBE(stop, this);
1919
1920 // Cleanup is handled in post_run()
1921 }
1922
1923 // Shared teardown for all JavaThreads
1924 void JavaThread::post_run() {
1925 this->exit(false);
1926 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1927 // for any shared tear-down.
1928 this->smr_delete();
1929 }
1930
1931 static void ensure_join(JavaThread* thread) {
1932 // We do not need to grab the Threads_lock, since we are operating on ourself.
1933 Handle threadObj(thread, thread->threadObj());
1934 assert(threadObj.not_null(), "java thread object must exist");
1935 ObjectLocker lock(threadObj, thread);
1936 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1937 thread->clear_pending_exception();
1938 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1939 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1940 // Clear the native thread instance - this makes isAlive return false and allows the join()
1941 // to complete once we've done the notify_all below
1942 java_lang_Thread::set_thread(threadObj(), NULL);
1943 lock.notify_all(thread);
1944 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1945 thread->clear_pending_exception();
1946 }
1947
1948 static bool is_daemon(oop threadObj) {
1949 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1950 }
1951
1952 // For any new cleanup additions, please check to see if they need to be applied to
1953 // cleanup_failed_attach_current_thread as well.
1954 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1955 assert(this == JavaThread::current(), "thread consistency check");
1956
1957 elapsedTimer _timer_exit_phase1;
1958 elapsedTimer _timer_exit_phase2;
1959 elapsedTimer _timer_exit_phase3;
1960 elapsedTimer _timer_exit_phase4;
1961
1962 if (log_is_enabled(Debug, os, thread, timer)) {
1963 _timer_exit_phase1.start();
1964 }
1965
1966 HandleMark hm(this);
1967 Handle uncaught_exception(this, this->pending_exception());
1968 this->clear_pending_exception();
1969 Handle threadObj(this, this->threadObj());
1970 assert(threadObj.not_null(), "Java thread object should be created");
1971
1972 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1973 {
1974 EXCEPTION_MARK;
1975
1976 CLEAR_PENDING_EXCEPTION;
1977 }
1978 if (!destroy_vm) {
1979 if (uncaught_exception.not_null()) {
1980 EXCEPTION_MARK;
1981 // Call method Thread.dispatchUncaughtException().
1982 Klass* thread_klass = SystemDictionary::Thread_klass();
1983 JavaValue result(T_VOID);
1984 JavaCalls::call_virtual(&result,
1985 threadObj, thread_klass,
1986 vmSymbols::dispatchUncaughtException_name(),
1987 vmSymbols::throwable_void_signature(),
1988 uncaught_exception,
1989 THREAD);
1990 if (HAS_PENDING_EXCEPTION) {
1991 ResourceMark rm(this);
1992 jio_fprintf(defaultStream::error_stream(),
1993 "\nException: %s thrown from the UncaughtExceptionHandler"
1994 " in thread \"%s\"\n",
1995 pending_exception()->klass()->external_name(),
1996 get_thread_name());
1997 CLEAR_PENDING_EXCEPTION;
1998 }
1999 }
2000 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2001
2002 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2003 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2004 // is deprecated anyhow.
2005 if (!is_Compiler_thread()) {
2006 int count = 3;
2007 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2008 EXCEPTION_MARK;
2009 JavaValue result(T_VOID);
2010 Klass* thread_klass = SystemDictionary::Thread_klass();
2011 JavaCalls::call_virtual(&result,
2012 threadObj, thread_klass,
2013 vmSymbols::exit_method_name(),
2014 vmSymbols::void_method_signature(),
2015 THREAD);
2016 CLEAR_PENDING_EXCEPTION;
2017 }
2018 }
2019 // notify JVMTI
2020 if (JvmtiExport::should_post_thread_life()) {
2021 JvmtiExport::post_thread_end(this);
2022 }
2023
2024 // We have notified the agents that we are exiting, before we go on,
2025 // we must check for a pending external suspend request and honor it
2026 // in order to not surprise the thread that made the suspend request.
2027 while (true) {
2028 {
2029 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2030 if (!is_external_suspend()) {
2031 set_terminated(_thread_exiting);
2032 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2033 break;
2034 }
2035 // Implied else:
2036 // Things get a little tricky here. We have a pending external
2037 // suspend request, but we are holding the SR_lock so we
2038 // can't just self-suspend. So we temporarily drop the lock
2039 // and then self-suspend.
2040 }
2041
2042 ThreadBlockInVM tbivm(this);
2043 java_suspend_self();
2044
2045 // We're done with this suspend request, but we have to loop around
2046 // and check again. Eventually we will get SR_lock without a pending
2047 // external suspend request and will be able to mark ourselves as
2048 // exiting.
2049 }
2050 // no more external suspends are allowed at this point
2051 } else {
2052 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2053 // before_exit() has already posted JVMTI THREAD_END events
2054 }
2055
2056 if (log_is_enabled(Debug, os, thread, timer)) {
2057 _timer_exit_phase1.stop();
2058 _timer_exit_phase2.start();
2059 }
2060
2061 // Capture daemon status before the thread is marked as terminated.
2062 bool daemon = is_daemon(threadObj());
2063
2064 // Notify waiters on thread object. This has to be done after exit() is called
2065 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2066 // group should have the destroyed bit set before waiters are notified).
2067 ensure_join(this);
2068 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2069
2070 if (log_is_enabled(Debug, os, thread, timer)) {
2071 _timer_exit_phase2.stop();
2072 _timer_exit_phase3.start();
2073 }
2074 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2075 // held by this thread must be released. The spec does not distinguish
2076 // between JNI-acquired and regular Java monitors. We can only see
2077 // regular Java monitors here if monitor enter-exit matching is broken.
2078 //
2079 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2080 // ObjectSynchronizer::release_monitors_owned_by_thread().
2081 if (exit_type == jni_detach) {
2082 // Sanity check even though JNI DetachCurrentThread() would have
2083 // returned JNI_ERR if there was a Java frame. JavaThread exit
2084 // should be done executing Java code by the time we get here.
2085 assert(!this->has_last_Java_frame(),
2086 "should not have a Java frame when detaching or exiting");
2087 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2088 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2089 }
2090
2091 // These things needs to be done while we are still a Java Thread. Make sure that thread
2092 // is in a consistent state, in case GC happens
2093 JFR_ONLY(Jfr::on_thread_exit(this);)
2094
2095 if (active_handles() != NULL) {
2096 JNIHandleBlock* block = active_handles();
2097 set_active_handles(NULL);
2098 JNIHandleBlock::release_block(block);
2099 }
2100
2101 if (free_handle_block() != NULL) {
2102 JNIHandleBlock* block = free_handle_block();
2103 set_free_handle_block(NULL);
2104 JNIHandleBlock::release_block(block);
2105 }
2106
2107 // These have to be removed while this is still a valid thread.
2108 remove_stack_guard_pages();
2109
2110 if (UseTLAB) {
2111 tlab().retire();
2112 }
2113
2114 if (JvmtiEnv::environments_might_exist()) {
2115 JvmtiExport::cleanup_thread(this);
2116 }
2117
2118 // We must flush any deferred card marks and other various GC barrier
2119 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2120 // before removing a thread from the list of active threads.
2121 BarrierSet::barrier_set()->on_thread_detach(this);
2122
2123 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2124 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2125 os::current_thread_id());
2126
2127 if (log_is_enabled(Debug, os, thread, timer)) {
2128 _timer_exit_phase3.stop();
2129 _timer_exit_phase4.start();
2130 }
2131 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2132 Threads::remove(this, daemon);
2133
2134 if (log_is_enabled(Debug, os, thread, timer)) {
2135 _timer_exit_phase4.stop();
2136 ResourceMark rm(this);
2137 log_debug(os, thread, timer)("name='%s'"
2138 ", exit-phase1=" JLONG_FORMAT
2139 ", exit-phase2=" JLONG_FORMAT
2140 ", exit-phase3=" JLONG_FORMAT
2141 ", exit-phase4=" JLONG_FORMAT,
2142 get_thread_name(),
2143 _timer_exit_phase1.milliseconds(),
2144 _timer_exit_phase2.milliseconds(),
2145 _timer_exit_phase3.milliseconds(),
2146 _timer_exit_phase4.milliseconds());
2147 }
2148 }
2149
2150 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2151 if (active_handles() != NULL) {
2152 JNIHandleBlock* block = active_handles();
2153 set_active_handles(NULL);
2154 JNIHandleBlock::release_block(block);
2155 }
2156
2157 if (free_handle_block() != NULL) {
2158 JNIHandleBlock* block = free_handle_block();
2159 set_free_handle_block(NULL);
2160 JNIHandleBlock::release_block(block);
2161 }
2162
2163 // These have to be removed while this is still a valid thread.
2164 remove_stack_guard_pages();
2165
2166 if (UseTLAB) {
2167 tlab().retire();
2168 }
2169
2170 BarrierSet::barrier_set()->on_thread_detach(this);
2171
2172 Threads::remove(this, is_daemon);
2173 this->smr_delete();
2174 }
2175
2176 JavaThread* JavaThread::active() {
2177 Thread* thread = Thread::current();
2178 if (thread->is_Java_thread()) {
2179 return (JavaThread*) thread;
2180 } else {
2181 assert(thread->is_VM_thread(), "this must be a vm thread");
2182 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2183 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2184 assert(ret->is_Java_thread(), "must be a Java thread");
2185 return ret;
2186 }
2187 }
2188
2189 bool JavaThread::is_lock_owned(address adr) const {
2190 if (Thread::is_lock_owned(adr)) return true;
2191
2192 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2193 if (chunk->contains(adr)) return true;
2194 }
2195
2196 return false;
2197 }
2198
2199
2200 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2201 chunk->set_next(monitor_chunks());
2202 set_monitor_chunks(chunk);
2203 }
2204
2205 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2206 guarantee(monitor_chunks() != NULL, "must be non empty");
2207 if (monitor_chunks() == chunk) {
2208 set_monitor_chunks(chunk->next());
2209 } else {
2210 MonitorChunk* prev = monitor_chunks();
2211 while (prev->next() != chunk) prev = prev->next();
2212 prev->set_next(chunk->next());
2213 }
2214 }
2215
2216 // JVM support.
2217
2218 // Note: this function shouldn't block if it's called in
2219 // _thread_in_native_trans state (such as from
2220 // check_special_condition_for_native_trans()).
2221 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2222
2223 if (has_last_Java_frame() && has_async_condition()) {
2224 // If we are at a polling page safepoint (not a poll return)
2225 // then we must defer async exception because live registers
2226 // will be clobbered by the exception path. Poll return is
2227 // ok because the call we a returning from already collides
2228 // with exception handling registers and so there is no issue.
2229 // (The exception handling path kills call result registers but
2230 // this is ok since the exception kills the result anyway).
2231
2232 if (is_at_poll_safepoint()) {
2233 // if the code we are returning to has deoptimized we must defer
2234 // the exception otherwise live registers get clobbered on the
2235 // exception path before deoptimization is able to retrieve them.
2236 //
2237 RegisterMap map(this, false);
2238 frame caller_fr = last_frame().sender(&map);
2239 assert(caller_fr.is_compiled_frame(), "what?");
2240 if (caller_fr.is_deoptimized_frame()) {
2241 log_info(exceptions)("deferred async exception at compiled safepoint");
2242 return;
2243 }
2244 }
2245 }
2246
2247 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2248 if (condition == _no_async_condition) {
2249 // Conditions have changed since has_special_runtime_exit_condition()
2250 // was called:
2251 // - if we were here only because of an external suspend request,
2252 // then that was taken care of above (or cancelled) so we are done
2253 // - if we were here because of another async request, then it has
2254 // been cleared between the has_special_runtime_exit_condition()
2255 // and now so again we are done
2256 return;
2257 }
2258
2259 // Check for pending async. exception
2260 if (_pending_async_exception != NULL) {
2261 // Only overwrite an already pending exception, if it is not a threadDeath.
2262 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2263
2264 // We cannot call Exceptions::_throw(...) here because we cannot block
2265 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2266
2267 LogTarget(Info, exceptions) lt;
2268 if (lt.is_enabled()) {
2269 ResourceMark rm;
2270 LogStream ls(lt);
2271 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2272 if (has_last_Java_frame()) {
2273 frame f = last_frame();
2274 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2275 }
2276 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2277 }
2278 _pending_async_exception = NULL;
2279 clear_has_async_exception();
2280 }
2281 }
2282
2283 if (check_unsafe_error &&
2284 condition == _async_unsafe_access_error && !has_pending_exception()) {
2285 condition = _no_async_condition; // done
2286 switch (thread_state()) {
2287 case _thread_in_vm: {
2288 JavaThread* THREAD = this;
2289 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2290 }
2291 case _thread_in_native: {
2292 ThreadInVMfromNative tiv(this);
2293 JavaThread* THREAD = this;
2294 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2295 }
2296 case _thread_in_Java: {
2297 ThreadInVMfromJava tiv(this);
2298 JavaThread* THREAD = this;
2299 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2300 }
2301 default:
2302 ShouldNotReachHere();
2303 }
2304 }
2305
2306 assert(condition == _no_async_condition || has_pending_exception() ||
2307 (!check_unsafe_error && condition == _async_unsafe_access_error),
2308 "must have handled the async condition, if no exception");
2309 }
2310
2311 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2312
2313 // Check for pending external suspend.
2314 if (is_external_suspend_with_lock()) {
2315 frame_anchor()->make_walkable(this);
2316 java_suspend_self_with_safepoint_check();
2317 }
2318
2319 // We might be here for reasons in addition to the self-suspend request
2320 // so check for other async requests.
2321 if (check_asyncs) {
2322 check_and_handle_async_exceptions();
2323 }
2324
2325 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2326 }
2327
2328 void JavaThread::send_thread_stop(oop java_throwable) {
2329 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2330 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2331 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2332
2333 // Do not throw asynchronous exceptions against the compiler thread
2334 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2335 if (!can_call_java()) return;
2336
2337 {
2338 // Actually throw the Throwable against the target Thread - however
2339 // only if there is no thread death exception installed already.
2340 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2341 // If the topmost frame is a runtime stub, then we are calling into
2342 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2343 // must deoptimize the caller before continuing, as the compiled exception handler table
2344 // may not be valid
2345 if (has_last_Java_frame()) {
2346 frame f = last_frame();
2347 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2348 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2349 RegisterMap reg_map(this, UseBiasedLocking);
2350 frame compiled_frame = f.sender(®_map);
2351 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2352 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2353 }
2354 }
2355 }
2356
2357 // Set async. pending exception in thread.
2358 set_pending_async_exception(java_throwable);
2359
2360 if (log_is_enabled(Info, exceptions)) {
2361 ResourceMark rm;
2362 log_info(exceptions)("Pending Async. exception installed of type: %s",
2363 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2364 }
2365 // for AbortVMOnException flag
2366 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2367 }
2368 }
2369
2370
2371 // Interrupt thread so it will wake up from a potential wait()
2372 Thread::interrupt(this);
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::deoptimized_wrt_marked_nmethods() {
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
2870 // If the caller is a NamedThread, then remember, in the current scope,
2871 // the given JavaThread in its _processed_thread field.
2872 class RememberProcessedThread: public StackObj {
2873 NamedThread* _cur_thr;
2874 public:
2875 RememberProcessedThread(JavaThread* jthr) {
2876 Thread* thread = Thread::current();
2877 if (thread->is_Named_thread()) {
2878 _cur_thr = (NamedThread *)thread;
2879 _cur_thr->set_processed_thread(jthr);
2880 } else {
2881 _cur_thr = NULL;
2882 }
2883 }
2884
2885 ~RememberProcessedThread() {
2886 if (_cur_thr) {
2887 _cur_thr->set_processed_thread(NULL);
2888 }
2889 }
2890 };
2891
2892 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2893 // Verify that the deferred card marks have been flushed.
2894 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2895
2896 // Traverse the GCHandles
2897 Thread::oops_do(f, cf);
2898
2899 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2900 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2901
2902 if (has_last_Java_frame()) {
2903 // Record JavaThread to GC thread
2904 RememberProcessedThread rpt(this);
2905
2906 // traverse the registered growable array
2907 if (_array_for_gc != NULL) {
2908 for (int index = 0; index < _array_for_gc->length(); index++) {
2909 f->do_oop(_array_for_gc->adr_at(index));
2910 }
2911 }
2912
2913 // Traverse the monitor chunks
2914 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2915 chunk->oops_do(f);
2916 }
2917
2918 // Traverse the execution stack
2919 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2920 fst.current()->oops_do(f, cf, fst.register_map());
2921 }
2922 }
2923
2924 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2925 // If we have deferred set_locals there might be oops waiting to be
2926 // written
2927 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2928 if (list != NULL) {
2929 for (int i = 0; i < list->length(); i++) {
2930 list->at(i)->oops_do(f);
2931 }
2932 }
2933
2934 // Traverse instance variables at the end since the GC may be moving things
2935 // around using this function
2936 f->do_oop((oop*) &_threadObj);
2937 f->do_oop((oop*) &_vm_result);
2938 f->do_oop((oop*) &_exception_oop);
2939 f->do_oop((oop*) &_pending_async_exception);
2940
2941 if (jvmti_thread_state() != NULL) {
2942 jvmti_thread_state()->oops_do(f);
2943 }
2944 }
2945
2946 #ifdef ASSERT
2947 void JavaThread::verify_states_for_handshake() {
2948 // This checks that the thread has a correct frame state during a handshake.
2949 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2950 (has_last_Java_frame() && java_call_counter() > 0),
2951 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2952 has_last_Java_frame(), java_call_counter());
2953 }
2954 #endif
2955
2956 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2957 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2958 (has_last_Java_frame() && java_call_counter() > 0),
2959 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2960 has_last_Java_frame(), java_call_counter());
2961
2962 if (has_last_Java_frame()) {
2963 // Traverse the execution stack
2964 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2965 fst.current()->nmethods_do(cf);
2966 }
2967 }
2968 }
2969
2970 void JavaThread::metadata_do(MetadataClosure* f) {
2971 if (has_last_Java_frame()) {
2972 // Traverse the execution stack to call f() on the methods in the stack
2973 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2974 fst.current()->metadata_do(f);
2975 }
2976 } else if (is_Compiler_thread()) {
2977 // need to walk ciMetadata in current compile tasks to keep alive.
2978 CompilerThread* ct = (CompilerThread*)this;
2979 if (ct->env() != NULL) {
2980 ct->env()->metadata_do(f);
2981 }
2982 CompileTask* task = ct->task();
2983 if (task != NULL) {
2984 task->metadata_do(f);
2985 }
2986 }
2987 }
2988
2989 // Printing
2990 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2991 switch (_thread_state) {
2992 case _thread_uninitialized: return "_thread_uninitialized";
2993 case _thread_new: return "_thread_new";
2994 case _thread_new_trans: return "_thread_new_trans";
2995 case _thread_in_native: return "_thread_in_native";
2996 case _thread_in_native_trans: return "_thread_in_native_trans";
2997 case _thread_in_vm: return "_thread_in_vm";
2998 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2999 case _thread_in_Java: return "_thread_in_Java";
3000 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3001 case _thread_blocked: return "_thread_blocked";
3002 case _thread_blocked_trans: return "_thread_blocked_trans";
3003 default: return "unknown thread state";
3004 }
3005 }
3006
3007 #ifndef PRODUCT
3008 void JavaThread::print_thread_state_on(outputStream *st) const {
3009 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3010 };
3011 #endif // PRODUCT
3012
3013 // Called by Threads::print() for VM_PrintThreads operation
3014 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3015 st->print_raw("\"");
3016 st->print_raw(get_thread_name());
3017 st->print_raw("\" ");
3018 oop thread_oop = threadObj();
3019 if (thread_oop != NULL) {
3020 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3021 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3022 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3023 }
3024 Thread::print_on(st, print_extended_info);
3025 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3026 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3027 if (thread_oop != NULL) {
3028 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3029 }
3030 #ifndef PRODUCT
3031 _safepoint_state->print_on(st);
3032 #endif // PRODUCT
3033 if (is_Compiler_thread()) {
3034 CompileTask *task = ((CompilerThread*)this)->task();
3035 if (task != NULL) {
3036 st->print(" Compiling: ");
3037 task->print(st, NULL, true, false);
3038 } else {
3039 st->print(" No compile task");
3040 }
3041 st->cr();
3042 }
3043 }
3044
3045 void JavaThread::print() const { print_on(tty); }
3046
3047 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3048 st->print("%s", get_thread_name_string(buf, buflen));
3049 }
3050
3051 // Called by fatal error handler. The difference between this and
3052 // JavaThread::print() is that we can't grab lock or allocate memory.
3053 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3054 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3055 oop thread_obj = threadObj();
3056 if (thread_obj != NULL) {
3057 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3058 }
3059 st->print(" [");
3060 st->print("%s", _get_thread_state_name(_thread_state));
3061 if (osthread()) {
3062 st->print(", id=%d", osthread()->thread_id());
3063 }
3064 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3065 p2i(stack_end()), p2i(stack_base()));
3066 st->print("]");
3067
3068 ThreadsSMRSupport::print_info_on(this, st);
3069 return;
3070 }
3071
3072 // Verification
3073
3074 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3075
3076 void JavaThread::verify() {
3077 // Verify oops in the thread.
3078 oops_do(&VerifyOopClosure::verify_oop, NULL);
3079
3080 // Verify the stack frames.
3081 frames_do(frame_verify);
3082 }
3083
3084 // CR 6300358 (sub-CR 2137150)
3085 // Most callers of this method assume that it can't return NULL but a
3086 // thread may not have a name whilst it is in the process of attaching to
3087 // the VM - see CR 6412693, and there are places where a JavaThread can be
3088 // seen prior to having it's threadObj set (eg JNI attaching threads and
3089 // if vm exit occurs during initialization). These cases can all be accounted
3090 // for such that this method never returns NULL.
3091 const char* JavaThread::get_thread_name() const {
3092 #ifdef ASSERT
3093 // early safepoints can hit while current thread does not yet have TLS
3094 if (!SafepointSynchronize::is_at_safepoint()) {
3095 Thread *cur = Thread::current();
3096 if (!(cur->is_Java_thread() && cur == this)) {
3097 // Current JavaThreads are allowed to get their own name without
3098 // the Threads_lock.
3099 assert_locked_or_safepoint(Threads_lock);
3100 }
3101 }
3102 #endif // ASSERT
3103 return get_thread_name_string();
3104 }
3105
3106 // Returns a non-NULL representation of this thread's name, or a suitable
3107 // descriptive string if there is no set name
3108 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3109 const char* name_str;
3110 oop thread_obj = threadObj();
3111 if (thread_obj != NULL) {
3112 oop name = java_lang_Thread::name(thread_obj);
3113 if (name != NULL) {
3114 if (buf == NULL) {
3115 name_str = java_lang_String::as_utf8_string(name);
3116 } else {
3117 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3118 }
3119 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3120 name_str = "<no-name - thread is attaching>";
3121 } else {
3122 name_str = Thread::name();
3123 }
3124 } else {
3125 name_str = Thread::name();
3126 }
3127 assert(name_str != NULL, "unexpected NULL thread name");
3128 return name_str;
3129 }
3130
3131 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3132
3133 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3134 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3135 // Link Java Thread object <-> C++ Thread
3136
3137 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3138 // and put it into a new Handle. The Handle "thread_oop" can then
3139 // be used to pass the C++ thread object to other methods.
3140
3141 // Set the Java level thread object (jthread) field of the
3142 // new thread (a JavaThread *) to C++ thread object using the
3143 // "thread_oop" handle.
3144
3145 // Set the thread field (a JavaThread *) of the
3146 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3147
3148 Handle thread_oop(Thread::current(),
3149 JNIHandles::resolve_non_null(jni_thread));
3150 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3151 "must be initialized");
3152 set_threadObj(thread_oop());
3153 java_lang_Thread::set_thread(thread_oop(), this);
3154
3155 if (prio == NoPriority) {
3156 prio = java_lang_Thread::priority(thread_oop());
3157 assert(prio != NoPriority, "A valid priority should be present");
3158 }
3159
3160 // Push the Java priority down to the native thread; needs Threads_lock
3161 Thread::set_priority(this, prio);
3162
3163 // Add the new thread to the Threads list and set it in motion.
3164 // We must have threads lock in order to call Threads::add.
3165 // It is crucial that we do not block before the thread is
3166 // added to the Threads list for if a GC happens, then the java_thread oop
3167 // will not be visited by GC.
3168 Threads::add(this);
3169 }
3170
3171 oop JavaThread::current_park_blocker() {
3172 // Support for JSR-166 locks
3173 oop thread_oop = threadObj();
3174 if (thread_oop != NULL) {
3175 return java_lang_Thread::park_blocker(thread_oop);
3176 }
3177 return NULL;
3178 }
3179
3180
3181 void JavaThread::print_stack_on(outputStream* st) {
3182 if (!has_last_Java_frame()) return;
3183 ResourceMark rm;
3184 HandleMark hm;
3185
3186 RegisterMap reg_map(this);
3187 vframe* start_vf = last_java_vframe(®_map);
3188 int count = 0;
3189 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3190 if (f->is_java_frame()) {
3191 javaVFrame* jvf = javaVFrame::cast(f);
3192 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3193
3194 // Print out lock information
3195 if (JavaMonitorsInStackTrace) {
3196 jvf->print_lock_info_on(st, count);
3197 }
3198 } else {
3199 // Ignore non-Java frames
3200 }
3201
3202 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3203 count++;
3204 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3205 }
3206 }
3207
3208
3209 // JVMTI PopFrame support
3210 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3211 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3212 if (in_bytes(size_in_bytes) != 0) {
3213 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3214 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3215 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3216 }
3217 }
3218
3219 void* JavaThread::popframe_preserved_args() {
3220 return _popframe_preserved_args;
3221 }
3222
3223 ByteSize JavaThread::popframe_preserved_args_size() {
3224 return in_ByteSize(_popframe_preserved_args_size);
3225 }
3226
3227 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3228 int sz = in_bytes(popframe_preserved_args_size());
3229 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3230 return in_WordSize(sz / wordSize);
3231 }
3232
3233 void JavaThread::popframe_free_preserved_args() {
3234 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3235 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3236 _popframe_preserved_args = NULL;
3237 _popframe_preserved_args_size = 0;
3238 }
3239
3240 #ifndef PRODUCT
3241
3242 void JavaThread::trace_frames() {
3243 tty->print_cr("[Describe stack]");
3244 int frame_no = 1;
3245 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3246 tty->print(" %d. ", frame_no++);
3247 fst.current()->print_value_on(tty, this);
3248 tty->cr();
3249 }
3250 }
3251
3252 class PrintAndVerifyOopClosure: public OopClosure {
3253 protected:
3254 template <class T> inline void do_oop_work(T* p) {
3255 oop obj = RawAccess<>::oop_load(p);
3256 if (obj == NULL) return;
3257 tty->print(INTPTR_FORMAT ": ", p2i(p));
3258 if (oopDesc::is_oop_or_null(obj)) {
3259 if (obj->is_objArray()) {
3260 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3261 } else {
3262 obj->print();
3263 }
3264 } else {
3265 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3266 }
3267 tty->cr();
3268 }
3269 public:
3270 virtual void do_oop(oop* p) { do_oop_work(p); }
3271 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3272 };
3273
3274 #ifdef ASSERT
3275 // Print or validate the layout of stack frames
3276 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3277 ResourceMark rm;
3278 PRESERVE_EXCEPTION_MARK;
3279 FrameValues values;
3280 int frame_no = 0;
3281 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3282 fst.current()->describe(values, ++frame_no);
3283 if (depth == frame_no) break;
3284 }
3285 if (validate_only) {
3286 values.validate();
3287 } else {
3288 tty->print_cr("[Describe stack layout]");
3289 values.print(this);
3290 }
3291 }
3292 #endif
3293
3294 void JavaThread::trace_stack_from(vframe* start_vf) {
3295 ResourceMark rm;
3296 int vframe_no = 1;
3297 for (vframe* f = start_vf; f; f = f->sender()) {
3298 if (f->is_java_frame()) {
3299 javaVFrame::cast(f)->print_activation(vframe_no++);
3300 } else {
3301 f->print();
3302 }
3303 if (vframe_no > StackPrintLimit) {
3304 tty->print_cr("...<more frames>...");
3305 return;
3306 }
3307 }
3308 }
3309
3310
3311 void JavaThread::trace_stack() {
3312 if (!has_last_Java_frame()) return;
3313 ResourceMark rm;
3314 HandleMark hm;
3315 RegisterMap reg_map(this);
3316 trace_stack_from(last_java_vframe(®_map));
3317 }
3318
3319
3320 #endif // PRODUCT
3321
3322
3323 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3324 assert(reg_map != NULL, "a map must be given");
3325 frame f = last_frame();
3326 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3327 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3328 }
3329 return NULL;
3330 }
3331
3332
3333 Klass* JavaThread::security_get_caller_class(int depth) {
3334 vframeStream vfst(this);
3335 vfst.security_get_caller_frame(depth);
3336 if (!vfst.at_end()) {
3337 return vfst.method()->method_holder();
3338 }
3339 return NULL;
3340 }
3341
3342 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3343 assert(thread->is_Compiler_thread(), "must be compiler thread");
3344 CompileBroker::compiler_thread_loop();
3345 }
3346
3347 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3348 NMethodSweeper::sweeper_loop();
3349 }
3350
3351 // Create a CompilerThread
3352 CompilerThread::CompilerThread(CompileQueue* queue,
3353 CompilerCounters* counters)
3354 : JavaThread(&compiler_thread_entry) {
3355 _env = NULL;
3356 _log = NULL;
3357 _task = NULL;
3358 _queue = queue;
3359 _counters = counters;
3360 _buffer_blob = NULL;
3361 _compiler = NULL;
3362
3363 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3364 resource_area()->bias_to(mtCompiler);
3365
3366 #ifndef PRODUCT
3367 _ideal_graph_printer = NULL;
3368 #endif
3369 }
3370
3371 CompilerThread::~CompilerThread() {
3372 // Delete objects which were allocated on heap.
3373 delete _counters;
3374 }
3375
3376 bool CompilerThread::can_call_java() const {
3377 return _compiler != NULL && _compiler->is_jvmci();
3378 }
3379
3380 // Create sweeper thread
3381 CodeCacheSweeperThread::CodeCacheSweeperThread()
3382 : JavaThread(&sweeper_thread_entry) {
3383 _scanned_compiled_method = NULL;
3384 }
3385
3386 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3387 JavaThread::oops_do(f, cf);
3388 if (_scanned_compiled_method != NULL && cf != NULL) {
3389 // Safepoints can occur when the sweeper is scanning an nmethod so
3390 // process it here to make sure it isn't unloaded in the middle of
3391 // a scan.
3392 cf->do_code_blob(_scanned_compiled_method);
3393 }
3394 }
3395
3396 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3397 JavaThread::nmethods_do(cf);
3398 if (_scanned_compiled_method != NULL && cf != NULL) {
3399 // Safepoints can occur when the sweeper is scanning an nmethod so
3400 // process it here to make sure it isn't unloaded in the middle of
3401 // a scan.
3402 cf->do_code_blob(_scanned_compiled_method);
3403 }
3404 }
3405
3406
3407 // ======= Threads ========
3408
3409 // The Threads class links together all active threads, and provides
3410 // operations over all threads. It is protected by the Threads_lock,
3411 // which is also used in other global contexts like safepointing.
3412 // ThreadsListHandles are used to safely perform operations on one
3413 // or more threads without the risk of the thread exiting during the
3414 // operation.
3415 //
3416 // Note: The Threads_lock is currently more widely used than we
3417 // would like. We are actively migrating Threads_lock uses to other
3418 // mechanisms in order to reduce Threads_lock contention.
3419
3420 int Threads::_number_of_threads = 0;
3421 int Threads::_number_of_non_daemon_threads = 0;
3422 int Threads::_return_code = 0;
3423 uintx Threads::_thread_claim_token = 1; // Never zero.
3424 size_t JavaThread::_stack_size_at_create = 0;
3425
3426 #ifdef ASSERT
3427 bool Threads::_vm_complete = false;
3428 #endif
3429
3430 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3431 Prefetch::read((void*)addr, prefetch_interval);
3432 return *addr;
3433 }
3434
3435 // Possibly the ugliest for loop the world has seen. C++ does not allow
3436 // multiple types in the declaration section of the for loop. In this case
3437 // we are only dealing with pointers and hence can cast them. It looks ugly
3438 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3439 #define DO_JAVA_THREADS(LIST, X) \
3440 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3441 *MACRO_list = (JavaThread*)(LIST), \
3442 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3443 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3444 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3445 MACRO_current_p != MACRO_end; \
3446 MACRO_current_p++, \
3447 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3448
3449 // All JavaThreads
3450 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3451
3452 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3453 void Threads::non_java_threads_do(ThreadClosure* tc) {
3454 NoSafepointVerifier nsv;
3455 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3456 tc->do_thread(njti.current());
3457 }
3458 }
3459
3460 // All JavaThreads
3461 void Threads::java_threads_do(ThreadClosure* tc) {
3462 assert_locked_or_safepoint(Threads_lock);
3463 // ALL_JAVA_THREADS iterates through all JavaThreads.
3464 ALL_JAVA_THREADS(p) {
3465 tc->do_thread(p);
3466 }
3467 }
3468
3469 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3470 assert_locked_or_safepoint(Threads_lock);
3471 java_threads_do(tc);
3472 tc->do_thread(VMThread::vm_thread());
3473 }
3474
3475 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3476 void Threads::threads_do(ThreadClosure* tc) {
3477 assert_locked_or_safepoint(Threads_lock);
3478 java_threads_do(tc);
3479 non_java_threads_do(tc);
3480 }
3481
3482 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3483 uintx claim_token = Threads::thread_claim_token();
3484 ALL_JAVA_THREADS(p) {
3485 if (p->claim_threads_do(is_par, claim_token)) {
3486 tc->do_thread(p);
3487 }
3488 }
3489 VMThread* vmt = VMThread::vm_thread();
3490 if (vmt->claim_threads_do(is_par, claim_token)) {
3491 tc->do_thread(vmt);
3492 }
3493 }
3494
3495 // The system initialization in the library has three phases.
3496 //
3497 // Phase 1: java.lang.System class initialization
3498 // java.lang.System is a primordial class loaded and initialized
3499 // by the VM early during startup. java.lang.System.<clinit>
3500 // only does registerNatives and keeps the rest of the class
3501 // initialization work later until thread initialization completes.
3502 //
3503 // System.initPhase1 initializes the system properties, the static
3504 // fields in, out, and err. Set up java signal handlers, OS-specific
3505 // system settings, and thread group of the main thread.
3506 static void call_initPhase1(TRAPS) {
3507 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3508 JavaValue result(T_VOID);
3509 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3510 vmSymbols::void_method_signature(), CHECK);
3511 }
3512
3513 // Phase 2. Module system initialization
3514 // This will initialize the module system. Only java.base classes
3515 // can be loaded until phase 2 completes.
3516 //
3517 // Call System.initPhase2 after the compiler initialization and jsr292
3518 // classes get initialized because module initialization runs a lot of java
3519 // code, that for performance reasons, should be compiled. Also, this will
3520 // enable the startup code to use lambda and other language features in this
3521 // phase and onward.
3522 //
3523 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3524 static void call_initPhase2(TRAPS) {
3525 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3526
3527 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3528
3529 JavaValue result(T_INT);
3530 JavaCallArguments args;
3531 args.push_int(DisplayVMOutputToStderr);
3532 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3533 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3534 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3535 if (result.get_jint() != JNI_OK) {
3536 vm_exit_during_initialization(); // no message or exception
3537 }
3538
3539 universe_post_module_init();
3540 }
3541
3542 // Phase 3. final setup - set security manager, system class loader and TCCL
3543 //
3544 // This will instantiate and set the security manager, set the system class
3545 // loader as well as the thread context class loader. The security manager
3546 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3547 // other modules or the application's classpath.
3548 static void call_initPhase3(TRAPS) {
3549 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3550 JavaValue result(T_VOID);
3551 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3552 vmSymbols::void_method_signature(), CHECK);
3553 }
3554
3555 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3556 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3557
3558 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3559 create_vm_init_libraries();
3560 }
3561
3562 initialize_class(vmSymbols::java_lang_String(), CHECK);
3563
3564 // Inject CompactStrings value after the static initializers for String ran.
3565 java_lang_String::set_compact_strings(CompactStrings);
3566
3567 // Initialize java_lang.System (needed before creating the thread)
3568 initialize_class(vmSymbols::java_lang_System(), CHECK);
3569 // The VM creates & returns objects of this class. Make sure it's initialized.
3570 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3571 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3572 Handle thread_group = create_initial_thread_group(CHECK);
3573 Universe::set_main_thread_group(thread_group());
3574 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3575 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3576 main_thread->set_threadObj(thread_object);
3577
3578 // Set thread status to running since main thread has
3579 // been started and running.
3580 java_lang_Thread::set_thread_status(thread_object,
3581 java_lang_Thread::RUNNABLE);
3582
3583 // The VM creates objects of this class.
3584 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3585
3586 #ifdef ASSERT
3587 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3588 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3589 #endif
3590
3591 // initialize the hardware-specific constants needed by Unsafe
3592 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3593 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3594
3595 // The VM preresolves methods to these classes. Make sure that they get initialized
3596 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3597 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3598
3599 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3600 call_initPhase1(CHECK);
3601
3602 // get the Java runtime name after java.lang.System is initialized
3603 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3604 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3605
3606 // an instance of OutOfMemory exception has been allocated earlier
3607 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3608 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3609 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3610 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3611 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3612 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3613 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3614 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3615
3616 // Eager box cache initialization only if AOT is on and any library is loaded.
3617 AOTLoader::initialize_box_caches(CHECK);
3618 }
3619
3620 void Threads::initialize_jsr292_core_classes(TRAPS) {
3621 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3622
3623 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3624 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3625 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3626 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3627 }
3628
3629 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3630 extern void JDK_Version_init();
3631
3632 // Preinitialize version info.
3633 VM_Version::early_initialize();
3634
3635 // Check version
3636 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3637
3638 // Initialize library-based TLS
3639 ThreadLocalStorage::init();
3640
3641 // Initialize the output stream module
3642 ostream_init();
3643
3644 // Process java launcher properties.
3645 Arguments::process_sun_java_launcher_properties(args);
3646
3647 // Initialize the os module
3648 os::init();
3649
3650 // Record VM creation timing statistics
3651 TraceVmCreationTime create_vm_timer;
3652 create_vm_timer.start();
3653
3654 // Initialize system properties.
3655 Arguments::init_system_properties();
3656
3657 // So that JDK version can be used as a discriminator when parsing arguments
3658 JDK_Version_init();
3659
3660 // Update/Initialize System properties after JDK version number is known
3661 Arguments::init_version_specific_system_properties();
3662
3663 // Make sure to initialize log configuration *before* parsing arguments
3664 LogConfiguration::initialize(create_vm_timer.begin_time());
3665
3666 // Parse arguments
3667 // Note: this internally calls os::init_container_support()
3668 jint parse_result = Arguments::parse(args);
3669 if (parse_result != JNI_OK) return parse_result;
3670
3671 os::init_before_ergo();
3672
3673 jint ergo_result = Arguments::apply_ergo();
3674 if (ergo_result != JNI_OK) return ergo_result;
3675
3676 // Final check of all ranges after ergonomics which may change values.
3677 if (!JVMFlagRangeList::check_ranges()) {
3678 return JNI_EINVAL;
3679 }
3680
3681 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3682 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3683 if (!constraint_result) {
3684 return JNI_EINVAL;
3685 }
3686
3687 JVMFlagWriteableList::mark_startup();
3688
3689 if (PauseAtStartup) {
3690 os::pause();
3691 }
3692
3693 HOTSPOT_VM_INIT_BEGIN();
3694
3695 // Timing (must come after argument parsing)
3696 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3697
3698 // Initialize the os module after parsing the args
3699 jint os_init_2_result = os::init_2();
3700 if (os_init_2_result != JNI_OK) return os_init_2_result;
3701
3702 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3703 // Initialize assert poison page mechanism.
3704 if (ShowRegistersOnAssert) {
3705 initialize_assert_poison();
3706 }
3707 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3708
3709 SafepointMechanism::initialize();
3710
3711 jint adjust_after_os_result = Arguments::adjust_after_os();
3712 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3713
3714 // Initialize output stream logging
3715 ostream_init_log();
3716
3717 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3718 // Must be before create_vm_init_agents()
3719 if (Arguments::init_libraries_at_startup()) {
3720 convert_vm_init_libraries_to_agents();
3721 }
3722
3723 // Launch -agentlib/-agentpath and converted -Xrun agents
3724 if (Arguments::init_agents_at_startup()) {
3725 create_vm_init_agents();
3726 }
3727
3728 // Initialize Threads state
3729 _number_of_threads = 0;
3730 _number_of_non_daemon_threads = 0;
3731
3732 // Initialize global data structures and create system classes in heap
3733 vm_init_globals();
3734
3735 #if INCLUDE_JVMCI
3736 if (JVMCICounterSize > 0) {
3737 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3738 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3739 } else {
3740 JavaThread::_jvmci_old_thread_counters = NULL;
3741 }
3742 #endif // INCLUDE_JVMCI
3743
3744 // Attach the main thread to this os thread
3745 JavaThread* main_thread = new JavaThread();
3746 main_thread->set_thread_state(_thread_in_vm);
3747 main_thread->initialize_thread_current();
3748 // must do this before set_active_handles
3749 main_thread->record_stack_base_and_size();
3750 main_thread->register_thread_stack_with_NMT();
3751 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3752
3753 if (!main_thread->set_as_starting_thread()) {
3754 vm_shutdown_during_initialization(
3755 "Failed necessary internal allocation. Out of swap space");
3756 main_thread->smr_delete();
3757 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3758 return JNI_ENOMEM;
3759 }
3760
3761 // Enable guard page *after* os::create_main_thread(), otherwise it would
3762 // crash Linux VM, see notes in os_linux.cpp.
3763 main_thread->create_stack_guard_pages();
3764
3765 // Initialize Java-Level synchronization subsystem
3766 ObjectMonitor::Initialize();
3767
3768 // Initialize global modules
3769 jint status = init_globals();
3770 if (status != JNI_OK) {
3771 main_thread->smr_delete();
3772 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3773 return status;
3774 }
3775
3776 JFR_ONLY(Jfr::on_vm_init();)
3777
3778 // Should be done after the heap is fully created
3779 main_thread->cache_global_variables();
3780
3781 HandleMark hm;
3782
3783 { MutexLocker mu(Threads_lock);
3784 Threads::add(main_thread);
3785 }
3786
3787 // Any JVMTI raw monitors entered in onload will transition into
3788 // real raw monitor. VM is setup enough here for raw monitor enter.
3789 JvmtiExport::transition_pending_onload_raw_monitors();
3790
3791 // Create the VMThread
3792 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3793
3794 VMThread::create();
3795 Thread* vmthread = VMThread::vm_thread();
3796
3797 if (!os::create_thread(vmthread, os::vm_thread)) {
3798 vm_exit_during_initialization("Cannot create VM thread. "
3799 "Out of system resources.");
3800 }
3801
3802 // Wait for the VM thread to become ready, and VMThread::run to initialize
3803 // Monitors can have spurious returns, must always check another state flag
3804 {
3805 MonitorLocker ml(Notify_lock);
3806 os::start_thread(vmthread);
3807 while (vmthread->active_handles() == NULL) {
3808 ml.wait();
3809 }
3810 }
3811 }
3812
3813 assert(Universe::is_fully_initialized(), "not initialized");
3814 if (VerifyDuringStartup) {
3815 // Make sure we're starting with a clean slate.
3816 VM_Verify verify_op;
3817 VMThread::execute(&verify_op);
3818 }
3819
3820 // We need this to update the java.vm.info property in case any flags used
3821 // to initially define it have been changed. This is needed for both CDS and
3822 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3823 // is initially computed. See Abstract_VM_Version::vm_info_string().
3824 // This update must happen before we initialize the java classes, but
3825 // after any initialization logic that might modify the flags.
3826 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3827
3828 Thread* THREAD = Thread::current();
3829
3830 // Always call even when there are not JVMTI environments yet, since environments
3831 // may be attached late and JVMTI must track phases of VM execution
3832 JvmtiExport::enter_early_start_phase();
3833
3834 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3835 JvmtiExport::post_early_vm_start();
3836
3837 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3838
3839 quicken_jni_functions();
3840
3841 // No more stub generation allowed after that point.
3842 StubCodeDesc::freeze();
3843
3844 // Set flag that basic initialization has completed. Used by exceptions and various
3845 // debug stuff, that does not work until all basic classes have been initialized.
3846 set_init_completed();
3847
3848 LogConfiguration::post_initialize();
3849 Metaspace::post_initialize();
3850
3851 HOTSPOT_VM_INIT_END();
3852
3853 // record VM initialization completion time
3854 #if INCLUDE_MANAGEMENT
3855 Management::record_vm_init_completed();
3856 #endif // INCLUDE_MANAGEMENT
3857
3858 // Signal Dispatcher needs to be started before VMInit event is posted
3859 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3860
3861 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3862 if (!DisableAttachMechanism) {
3863 AttachListener::vm_start();
3864 if (StartAttachListener || AttachListener::init_at_startup()) {
3865 AttachListener::init();
3866 }
3867 }
3868
3869 // Launch -Xrun agents
3870 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3871 // back-end can launch with -Xdebug -Xrunjdwp.
3872 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3873 create_vm_init_libraries();
3874 }
3875
3876 if (CleanChunkPoolAsync) {
3877 Chunk::start_chunk_pool_cleaner_task();
3878 }
3879
3880
3881 // initialize compiler(s)
3882 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3883 #if INCLUDE_JVMCI
3884 bool force_JVMCI_intialization = false;
3885 if (EnableJVMCI) {
3886 // Initialize JVMCI eagerly when it is explicitly requested.
3887 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3888 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3889
3890 if (!force_JVMCI_intialization) {
3891 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3892 // compilations via JVMCI will not actually block until JVMCI is initialized.
3893 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3894 }
3895 }
3896 #endif
3897 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3898 // Postpone completion of compiler initialization to after JVMCI
3899 // is initialized to avoid timeouts of blocking compilations.
3900 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3901 CompileBroker::compilation_init_phase2();
3902 }
3903 #endif
3904
3905 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3906 // It is done after compilers are initialized, because otherwise compilations of
3907 // signature polymorphic MH intrinsics can be missed
3908 // (see SystemDictionary::find_method_handle_intrinsic).
3909 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3910
3911 // This will initialize the module system. Only java.base classes can be
3912 // loaded until phase 2 completes
3913 call_initPhase2(CHECK_JNI_ERR);
3914
3915 // Always call even when there are not JVMTI environments yet, since environments
3916 // may be attached late and JVMTI must track phases of VM execution
3917 JvmtiExport::enter_start_phase();
3918
3919 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3920 JvmtiExport::post_vm_start();
3921
3922 // Final system initialization including security manager and system class loader
3923 call_initPhase3(CHECK_JNI_ERR);
3924
3925 // cache the system and platform class loaders
3926 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3927
3928 #if INCLUDE_CDS
3929 // capture the module path info from the ModuleEntryTable
3930 ClassLoader::initialize_module_path(THREAD);
3931 #endif
3932
3933 #if INCLUDE_JVMCI
3934 if (force_JVMCI_intialization) {
3935 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3936 CompileBroker::compilation_init_phase2();
3937 }
3938 #endif
3939
3940 // Always call even when there are not JVMTI environments yet, since environments
3941 // may be attached late and JVMTI must track phases of VM execution
3942 JvmtiExport::enter_live_phase();
3943
3944 // Make perfmemory accessible
3945 PerfMemory::set_accessible(true);
3946
3947 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3948 JvmtiExport::post_vm_initialized();
3949
3950 JFR_ONLY(Jfr::on_vm_start();)
3951
3952 #if INCLUDE_MANAGEMENT
3953 Management::initialize(THREAD);
3954
3955 if (HAS_PENDING_EXCEPTION) {
3956 // management agent fails to start possibly due to
3957 // configuration problem and is responsible for printing
3958 // stack trace if appropriate. Simply exit VM.
3959 vm_exit(1);
3960 }
3961 #endif // INCLUDE_MANAGEMENT
3962
3963 if (MemProfiling) MemProfiler::engage();
3964 StatSampler::engage();
3965 if (CheckJNICalls) JniPeriodicChecker::engage();
3966
3967 BiasedLocking::init();
3968
3969 #if INCLUDE_RTM_OPT
3970 RTMLockingCounters::init();
3971 #endif
3972
3973 call_postVMInitHook(THREAD);
3974 // The Java side of PostVMInitHook.run must deal with all
3975 // exceptions and provide means of diagnosis.
3976 if (HAS_PENDING_EXCEPTION) {
3977 CLEAR_PENDING_EXCEPTION;
3978 }
3979
3980 {
3981 MutexLocker ml(PeriodicTask_lock);
3982 // Make sure the WatcherThread can be started by WatcherThread::start()
3983 // or by dynamic enrollment.
3984 WatcherThread::make_startable();
3985 // Start up the WatcherThread if there are any periodic tasks
3986 // NOTE: All PeriodicTasks should be registered by now. If they
3987 // aren't, late joiners might appear to start slowly (we might
3988 // take a while to process their first tick).
3989 if (PeriodicTask::num_tasks() > 0) {
3990 WatcherThread::start();
3991 }
3992 }
3993
3994 create_vm_timer.end();
3995 #ifdef ASSERT
3996 _vm_complete = true;
3997 #endif
3998
3999 if (DumpSharedSpaces) {
4000 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4001 ShouldNotReachHere();
4002 }
4003
4004 return JNI_OK;
4005 }
4006
4007 // type for the Agent_OnLoad and JVM_OnLoad entry points
4008 extern "C" {
4009 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4010 }
4011 // Find a command line agent library and return its entry point for
4012 // -agentlib: -agentpath: -Xrun
4013 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4014 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4015 const char *on_load_symbols[],
4016 size_t num_symbol_entries) {
4017 OnLoadEntry_t on_load_entry = NULL;
4018 void *library = NULL;
4019
4020 if (!agent->valid()) {
4021 char buffer[JVM_MAXPATHLEN];
4022 char ebuf[1024] = "";
4023 const char *name = agent->name();
4024 const char *msg = "Could not find agent library ";
4025
4026 // First check to see if agent is statically linked into executable
4027 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4028 library = agent->os_lib();
4029 } else if (agent->is_absolute_path()) {
4030 library = os::dll_load(name, ebuf, sizeof ebuf);
4031 if (library == NULL) {
4032 const char *sub_msg = " in absolute path, with error: ";
4033 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4034 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4035 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4036 // If we can't find the agent, exit.
4037 vm_exit_during_initialization(buf, NULL);
4038 FREE_C_HEAP_ARRAY(char, buf);
4039 }
4040 } else {
4041 // Try to load the agent from the standard dll directory
4042 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4043 name)) {
4044 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4045 }
4046 if (library == NULL) { // Try the library path directory.
4047 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4048 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4049 }
4050 if (library == NULL) {
4051 const char *sub_msg = " on the library path, with error: ";
4052 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4053
4054 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4055 strlen(ebuf) + strlen(sub_msg2) + 1;
4056 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4057 if (!agent->is_instrument_lib()) {
4058 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4059 } else {
4060 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4061 }
4062 // If we can't find the agent, exit.
4063 vm_exit_during_initialization(buf, NULL);
4064 FREE_C_HEAP_ARRAY(char, buf);
4065 }
4066 }
4067 }
4068 agent->set_os_lib(library);
4069 agent->set_valid();
4070 }
4071
4072 // Find the OnLoad function.
4073 on_load_entry =
4074 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4075 false,
4076 on_load_symbols,
4077 num_symbol_entries));
4078 return on_load_entry;
4079 }
4080
4081 // Find the JVM_OnLoad entry point
4082 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4083 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4084 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4085 }
4086
4087 // Find the Agent_OnLoad entry point
4088 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4089 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4090 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4091 }
4092
4093 // For backwards compatibility with -Xrun
4094 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4095 // treated like -agentpath:
4096 // Must be called before agent libraries are created
4097 void Threads::convert_vm_init_libraries_to_agents() {
4098 AgentLibrary* agent;
4099 AgentLibrary* next;
4100
4101 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4102 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4103 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4104
4105 // If there is an JVM_OnLoad function it will get called later,
4106 // otherwise see if there is an Agent_OnLoad
4107 if (on_load_entry == NULL) {
4108 on_load_entry = lookup_agent_on_load(agent);
4109 if (on_load_entry != NULL) {
4110 // switch it to the agent list -- so that Agent_OnLoad will be called,
4111 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4112 Arguments::convert_library_to_agent(agent);
4113 } else {
4114 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4115 }
4116 }
4117 }
4118 }
4119
4120 // Create agents for -agentlib: -agentpath: and converted -Xrun
4121 // Invokes Agent_OnLoad
4122 // Called very early -- before JavaThreads exist
4123 void Threads::create_vm_init_agents() {
4124 extern struct JavaVM_ main_vm;
4125 AgentLibrary* agent;
4126
4127 JvmtiExport::enter_onload_phase();
4128
4129 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4130 // CDS dumping does not support native JVMTI agent.
4131 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4132 if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4133 if(!agent->is_instrument_lib()) {
4134 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4135 } else if (!AllowArchivingWithJavaAgent) {
4136 vm_exit_during_cds_dumping(
4137 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4138 }
4139 }
4140
4141 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4142
4143 if (on_load_entry != NULL) {
4144 // Invoke the Agent_OnLoad function
4145 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4146 if (err != JNI_OK) {
4147 vm_exit_during_initialization("agent library failed to init", agent->name());
4148 }
4149 } else {
4150 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4151 }
4152 }
4153
4154 JvmtiExport::enter_primordial_phase();
4155 }
4156
4157 extern "C" {
4158 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4159 }
4160
4161 void Threads::shutdown_vm_agents() {
4162 // Send any Agent_OnUnload notifications
4163 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4164 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4165 extern struct JavaVM_ main_vm;
4166 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4167
4168 // Find the Agent_OnUnload function.
4169 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4170 os::find_agent_function(agent,
4171 false,
4172 on_unload_symbols,
4173 num_symbol_entries));
4174
4175 // Invoke the Agent_OnUnload function
4176 if (unload_entry != NULL) {
4177 JavaThread* thread = JavaThread::current();
4178 ThreadToNativeFromVM ttn(thread);
4179 HandleMark hm(thread);
4180 (*unload_entry)(&main_vm);
4181 }
4182 }
4183 }
4184
4185 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4186 // Invokes JVM_OnLoad
4187 void Threads::create_vm_init_libraries() {
4188 extern struct JavaVM_ main_vm;
4189 AgentLibrary* agent;
4190
4191 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4192 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4193
4194 if (on_load_entry != NULL) {
4195 // Invoke the JVM_OnLoad function
4196 JavaThread* thread = JavaThread::current();
4197 ThreadToNativeFromVM ttn(thread);
4198 HandleMark hm(thread);
4199 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4200 if (err != JNI_OK) {
4201 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4202 }
4203 } else {
4204 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4205 }
4206 }
4207 }
4208
4209
4210 // Last thread running calls java.lang.Shutdown.shutdown()
4211 void JavaThread::invoke_shutdown_hooks() {
4212 HandleMark hm(this);
4213
4214 // We could get here with a pending exception, if so clear it now.
4215 if (this->has_pending_exception()) {
4216 this->clear_pending_exception();
4217 }
4218
4219 EXCEPTION_MARK;
4220 Klass* shutdown_klass =
4221 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4222 THREAD);
4223 if (shutdown_klass != NULL) {
4224 // SystemDictionary::resolve_or_null will return null if there was
4225 // an exception. If we cannot load the Shutdown class, just don't
4226 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4227 // won't be run. Note that if a shutdown hook was registered,
4228 // the Shutdown class would have already been loaded
4229 // (Runtime.addShutdownHook will load it).
4230 JavaValue result(T_VOID);
4231 JavaCalls::call_static(&result,
4232 shutdown_klass,
4233 vmSymbols::shutdown_name(),
4234 vmSymbols::void_method_signature(),
4235 THREAD);
4236 }
4237 CLEAR_PENDING_EXCEPTION;
4238 }
4239
4240 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4241 // the program falls off the end of main(). Another VM exit path is through
4242 // vm_exit() when the program calls System.exit() to return a value or when
4243 // there is a serious error in VM. The two shutdown paths are not exactly
4244 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4245 // and VM_Exit op at VM level.
4246 //
4247 // Shutdown sequence:
4248 // + Shutdown native memory tracking if it is on
4249 // + Wait until we are the last non-daemon thread to execute
4250 // <-- every thing is still working at this moment -->
4251 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4252 // shutdown hooks
4253 // + Call before_exit(), prepare for VM exit
4254 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4255 // currently the only user of this mechanism is File.deleteOnExit())
4256 // > stop StatSampler, watcher thread, CMS threads,
4257 // post thread end and vm death events to JVMTI,
4258 // stop signal thread
4259 // + Call JavaThread::exit(), it will:
4260 // > release JNI handle blocks, remove stack guard pages
4261 // > remove this thread from Threads list
4262 // <-- no more Java code from this thread after this point -->
4263 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4264 // the compiler threads at safepoint
4265 // <-- do not use anything that could get blocked by Safepoint -->
4266 // + Disable tracing at JNI/JVM barriers
4267 // + Set _vm_exited flag for threads that are still running native code
4268 // + Call exit_globals()
4269 // > deletes tty
4270 // > deletes PerfMemory resources
4271 // + Delete this thread
4272 // + Return to caller
4273
4274 bool Threads::destroy_vm() {
4275 JavaThread* thread = JavaThread::current();
4276
4277 #ifdef ASSERT
4278 _vm_complete = false;
4279 #endif
4280 // Wait until we are the last non-daemon thread to execute
4281 { MonitorLocker nu(Threads_lock);
4282 while (Threads::number_of_non_daemon_threads() > 1)
4283 // This wait should make safepoint checks, wait without a timeout,
4284 // and wait as a suspend-equivalent condition.
4285 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4286 }
4287
4288 EventShutdown e;
4289 if (e.should_commit()) {
4290 e.set_reason("No remaining non-daemon Java threads");
4291 e.commit();
4292 }
4293
4294 // Hang forever on exit if we are reporting an error.
4295 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4296 os::infinite_sleep();
4297 }
4298 os::wait_for_keypress_at_exit();
4299
4300 // run Java level shutdown hooks
4301 thread->invoke_shutdown_hooks();
4302
4303 before_exit(thread);
4304
4305 thread->exit(true);
4306
4307 // Stop VM thread.
4308 {
4309 // 4945125 The vm thread comes to a safepoint during exit.
4310 // GC vm_operations can get caught at the safepoint, and the
4311 // heap is unparseable if they are caught. Grab the Heap_lock
4312 // to prevent this. The GC vm_operations will not be able to
4313 // queue until after the vm thread is dead. After this point,
4314 // we'll never emerge out of the safepoint before the VM exits.
4315
4316 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4317
4318 VMThread::wait_for_vm_thread_exit();
4319 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4320 VMThread::destroy();
4321 }
4322
4323 // Now, all Java threads are gone except daemon threads. Daemon threads
4324 // running Java code or in VM are stopped by the Safepoint. However,
4325 // daemon threads executing native code are still running. But they
4326 // will be stopped at native=>Java/VM barriers. Note that we can't
4327 // simply kill or suspend them, as it is inherently deadlock-prone.
4328
4329 VM_Exit::set_vm_exited();
4330
4331 // Clean up ideal graph printers after the VMThread has started
4332 // the final safepoint which will block all the Compiler threads.
4333 // Note that this Thread has already logically exited so the
4334 // clean_up() function's use of a JavaThreadIteratorWithHandle
4335 // would be a problem except set_vm_exited() has remembered the
4336 // shutdown thread which is granted a policy exception.
4337 #if defined(COMPILER2) && !defined(PRODUCT)
4338 IdealGraphPrinter::clean_up();
4339 #endif
4340
4341 notify_vm_shutdown();
4342
4343 // exit_globals() will delete tty
4344 exit_globals();
4345
4346 // We are after VM_Exit::set_vm_exited() so we can't call
4347 // thread->smr_delete() or we will block on the Threads_lock.
4348 // Deleting the shutdown thread here is safe because another
4349 // JavaThread cannot have an active ThreadsListHandle for
4350 // this JavaThread.
4351 delete thread;
4352
4353 #if INCLUDE_JVMCI
4354 if (JVMCICounterSize > 0) {
4355 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4356 }
4357 #endif
4358
4359 LogConfiguration::finalize();
4360
4361 return true;
4362 }
4363
4364
4365 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4366 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4367 return is_supported_jni_version(version);
4368 }
4369
4370
4371 jboolean Threads::is_supported_jni_version(jint version) {
4372 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4373 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4374 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4375 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4376 if (version == JNI_VERSION_9) return JNI_TRUE;
4377 if (version == JNI_VERSION_10) return JNI_TRUE;
4378 return JNI_FALSE;
4379 }
4380
4381
4382 void Threads::add(JavaThread* p, bool force_daemon) {
4383 // The threads lock must be owned at this point
4384 assert(Threads_lock->owned_by_self(), "must have threads lock");
4385
4386 BarrierSet::barrier_set()->on_thread_attach(p);
4387
4388 // Once a JavaThread is added to the Threads list, smr_delete() has
4389 // to be used to delete it. Otherwise we can just delete it directly.
4390 p->set_on_thread_list();
4391
4392 _number_of_threads++;
4393 oop threadObj = p->threadObj();
4394 bool daemon = true;
4395 // Bootstrapping problem: threadObj can be null for initial
4396 // JavaThread (or for threads attached via JNI)
4397 if ((!force_daemon) && !is_daemon((threadObj))) {
4398 _number_of_non_daemon_threads++;
4399 daemon = false;
4400 }
4401
4402 ThreadService::add_thread(p, daemon);
4403
4404 // Maintain fast thread list
4405 ThreadsSMRSupport::add_thread(p);
4406
4407 // Possible GC point.
4408 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4409 }
4410
4411 void Threads::remove(JavaThread* p, bool is_daemon) {
4412
4413 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4414 ObjectSynchronizer::om_flush(p);
4415
4416 // Extra scope needed for Thread_lock, so we can check
4417 // that we do not remove thread without safepoint code notice
4418 { MonitorLocker ml(Threads_lock);
4419
4420 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4421
4422 // Maintain fast thread list
4423 ThreadsSMRSupport::remove_thread(p);
4424
4425 _number_of_threads--;
4426 if (!is_daemon) {
4427 _number_of_non_daemon_threads--;
4428
4429 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4430 // on destroy_vm will wake up.
4431 if (number_of_non_daemon_threads() == 1) {
4432 ml.notify_all();
4433 }
4434 }
4435 ThreadService::remove_thread(p, is_daemon);
4436
4437 // Make sure that safepoint code disregard this thread. This is needed since
4438 // the thread might mess around with locks after this point. This can cause it
4439 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4440 // of this thread since it is removed from the queue.
4441 p->set_terminated_value();
4442 } // unlock Threads_lock
4443
4444 // Since Events::log uses a lock, we grab it outside the Threads_lock
4445 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4446 }
4447
4448 // Operations on the Threads list for GC. These are not explicitly locked,
4449 // but the garbage collector must provide a safe context for them to run.
4450 // In particular, these things should never be called when the Threads_lock
4451 // is held by some other thread. (Note: the Safepoint abstraction also
4452 // uses the Threads_lock to guarantee this property. It also makes sure that
4453 // all threads gets blocked when exiting or starting).
4454
4455 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4456 ALL_JAVA_THREADS(p) {
4457 p->oops_do(f, cf);
4458 }
4459 VMThread::vm_thread()->oops_do(f, cf);
4460 }
4461
4462 void Threads::change_thread_claim_token() {
4463 if (++_thread_claim_token == 0) {
4464 // On overflow of the token counter, there is a risk of future
4465 // collisions between a new global token value and a stale token
4466 // for a thread, because not all iterations visit all threads.
4467 // (Though it's pretty much a theoretical concern for non-trivial
4468 // token counter sizes.) To deal with the possibility, reset all
4469 // the thread tokens to zero on global token overflow.
4470 struct ResetClaims : public ThreadClosure {
4471 virtual void do_thread(Thread* t) {
4472 t->claim_threads_do(false, 0);
4473 }
4474 } reset_claims;
4475 Threads::threads_do(&reset_claims);
4476 // On overflow, update the global token to non-zero, to
4477 // avoid the special "never claimed" initial thread value.
4478 _thread_claim_token = 1;
4479 }
4480 }
4481
4482 #ifdef ASSERT
4483 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4484 const uintx token = t->threads_do_token();
4485 assert(token == expected,
4486 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4487 UINTX_FORMAT, kind, p2i(t), token, expected);
4488 }
4489
4490 void Threads::assert_all_threads_claimed() {
4491 ALL_JAVA_THREADS(p) {
4492 assert_thread_claimed("Thread", p, _thread_claim_token);
4493 }
4494 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4495 }
4496 #endif // ASSERT
4497
4498 class ParallelOopsDoThreadClosure : public ThreadClosure {
4499 private:
4500 OopClosure* _f;
4501 CodeBlobClosure* _cf;
4502 public:
4503 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4504 void do_thread(Thread* t) {
4505 t->oops_do(_f, _cf);
4506 }
4507 };
4508
4509 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4510 ParallelOopsDoThreadClosure tc(f, cf);
4511 possibly_parallel_threads_do(is_par, &tc);
4512 }
4513
4514 void Threads::nmethods_do(CodeBlobClosure* cf) {
4515 ALL_JAVA_THREADS(p) {
4516 // This is used by the code cache sweeper to mark nmethods that are active
4517 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4518 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4519 if(!p->is_Code_cache_sweeper_thread()) {
4520 p->nmethods_do(cf);
4521 }
4522 }
4523 }
4524
4525 void Threads::metadata_do(MetadataClosure* f) {
4526 ALL_JAVA_THREADS(p) {
4527 p->metadata_do(f);
4528 }
4529 }
4530
4531 class ThreadHandlesClosure : public ThreadClosure {
4532 void (*_f)(Metadata*);
4533 public:
4534 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4535 virtual void do_thread(Thread* thread) {
4536 thread->metadata_handles_do(_f);
4537 }
4538 };
4539
4540 void Threads::metadata_handles_do(void f(Metadata*)) {
4541 // Only walk the Handles in Thread.
4542 ThreadHandlesClosure handles_closure(f);
4543 threads_do(&handles_closure);
4544 }
4545
4546 void Threads::deoptimized_wrt_marked_nmethods() {
4547 ALL_JAVA_THREADS(p) {
4548 p->deoptimized_wrt_marked_nmethods();
4549 }
4550 }
4551
4552
4553 // Get count Java threads that are waiting to enter the specified monitor.
4554 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4555 int count,
4556 address monitor) {
4557 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4558
4559 int i = 0;
4560 DO_JAVA_THREADS(t_list, p) {
4561 if (!p->can_call_java()) continue;
4562
4563 address pending = (address)p->current_pending_monitor();
4564 if (pending == monitor) { // found a match
4565 if (i < count) result->append(p); // save the first count matches
4566 i++;
4567 }
4568 }
4569
4570 return result;
4571 }
4572
4573
4574 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4575 address owner) {
4576 // NULL owner means not locked so we can skip the search
4577 if (owner == NULL) return NULL;
4578
4579 DO_JAVA_THREADS(t_list, p) {
4580 // first, see if owner is the address of a Java thread
4581 if (owner == (address)p) return p;
4582 }
4583
4584 // Cannot assert on lack of success here since this function may be
4585 // used by code that is trying to report useful problem information
4586 // like deadlock detection.
4587 if (UseHeavyMonitors) return NULL;
4588
4589 // If we didn't find a matching Java thread and we didn't force use of
4590 // heavyweight monitors, then the owner is the stack address of the
4591 // Lock Word in the owning Java thread's stack.
4592 //
4593 JavaThread* the_owner = NULL;
4594 DO_JAVA_THREADS(t_list, q) {
4595 if (q->is_lock_owned(owner)) {
4596 the_owner = q;
4597 break;
4598 }
4599 }
4600
4601 // cannot assert on lack of success here; see above comment
4602 return the_owner;
4603 }
4604
4605 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4606 void Threads::print_on(outputStream* st, bool print_stacks,
4607 bool internal_format, bool print_concurrent_locks,
4608 bool print_extended_info) {
4609 char buf[32];
4610 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4611
4612 st->print_cr("Full thread dump %s (%s %s):",
4613 VM_Version::vm_name(),
4614 VM_Version::vm_release(),
4615 VM_Version::vm_info_string());
4616 st->cr();
4617
4618 #if INCLUDE_SERVICES
4619 // Dump concurrent locks
4620 ConcurrentLocksDump concurrent_locks;
4621 if (print_concurrent_locks) {
4622 concurrent_locks.dump_at_safepoint();
4623 }
4624 #endif // INCLUDE_SERVICES
4625
4626 ThreadsSMRSupport::print_info_on(st);
4627 st->cr();
4628
4629 ALL_JAVA_THREADS(p) {
4630 ResourceMark rm;
4631 p->print_on(st, print_extended_info);
4632 if (print_stacks) {
4633 if (internal_format) {
4634 p->trace_stack();
4635 } else {
4636 p->print_stack_on(st);
4637 }
4638 }
4639 st->cr();
4640 #if INCLUDE_SERVICES
4641 if (print_concurrent_locks) {
4642 concurrent_locks.print_locks_on(p, st);
4643 }
4644 #endif // INCLUDE_SERVICES
4645 }
4646
4647 VMThread::vm_thread()->print_on(st);
4648 st->cr();
4649 Universe::heap()->print_gc_threads_on(st);
4650 WatcherThread* wt = WatcherThread::watcher_thread();
4651 if (wt != NULL) {
4652 wt->print_on(st);
4653 st->cr();
4654 }
4655
4656 st->flush();
4657 }
4658
4659 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4660 int buflen, bool* found_current) {
4661 if (this_thread != NULL) {
4662 bool is_current = (current == this_thread);
4663 *found_current = *found_current || is_current;
4664 st->print("%s", is_current ? "=>" : " ");
4665
4666 st->print(PTR_FORMAT, p2i(this_thread));
4667 st->print(" ");
4668 this_thread->print_on_error(st, buf, buflen);
4669 st->cr();
4670 }
4671 }
4672
4673 class PrintOnErrorClosure : public ThreadClosure {
4674 outputStream* _st;
4675 Thread* _current;
4676 char* _buf;
4677 int _buflen;
4678 bool* _found_current;
4679 public:
4680 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4681 int buflen, bool* found_current) :
4682 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4683
4684 virtual void do_thread(Thread* thread) {
4685 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4686 }
4687 };
4688
4689 // Threads::print_on_error() is called by fatal error handler. It's possible
4690 // that VM is not at safepoint and/or current thread is inside signal handler.
4691 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4692 // memory (even in resource area), it might deadlock the error handler.
4693 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4694 int buflen) {
4695 ThreadsSMRSupport::print_info_on(st);
4696 st->cr();
4697
4698 bool found_current = false;
4699 st->print_cr("Java Threads: ( => current thread )");
4700 ALL_JAVA_THREADS(thread) {
4701 print_on_error(thread, st, current, buf, buflen, &found_current);
4702 }
4703 st->cr();
4704
4705 st->print_cr("Other Threads:");
4706 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4707 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4708
4709 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4710 Universe::heap()->gc_threads_do(&print_closure);
4711
4712 if (!found_current) {
4713 st->cr();
4714 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4715 current->print_on_error(st, buf, buflen);
4716 st->cr();
4717 }
4718 st->cr();
4719
4720 st->print_cr("Threads with active compile tasks:");
4721 print_threads_compiling(st, buf, buflen);
4722 }
4723
4724 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4725 ALL_JAVA_THREADS(thread) {
4726 if (thread->is_Compiler_thread()) {
4727 CompilerThread* ct = (CompilerThread*) thread;
4728
4729 // Keep task in local variable for NULL check.
4730 // ct->_task might be set to NULL by concurring compiler thread
4731 // because it completed the compilation. The task is never freed,
4732 // though, just returned to a free list.
4733 CompileTask* task = ct->task();
4734 if (task != NULL) {
4735 thread->print_name_on_error(st, buf, buflen);
4736 st->print(" ");
4737 task->print(st, NULL, short_form, true);
4738 }
4739 }
4740 }
4741 }
4742
4743
4744 // Internal SpinLock and Mutex
4745 // Based on ParkEvent
4746
4747 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4748 //
4749 // We employ SpinLocks _only for low-contention, fixed-length
4750 // short-duration critical sections where we're concerned
4751 // about native mutex_t or HotSpot Mutex:: latency.
4752 // The mux construct provides a spin-then-block mutual exclusion
4753 // mechanism.
4754 //
4755 // Testing has shown that contention on the ListLock guarding gFreeList
4756 // is common. If we implement ListLock as a simple SpinLock it's common
4757 // for the JVM to devolve to yielding with little progress. This is true
4758 // despite the fact that the critical sections protected by ListLock are
4759 // extremely short.
4760 //
4761 // TODO-FIXME: ListLock should be of type SpinLock.
4762 // We should make this a 1st-class type, integrated into the lock
4763 // hierarchy as leaf-locks. Critically, the SpinLock structure
4764 // should have sufficient padding to avoid false-sharing and excessive
4765 // cache-coherency traffic.
4766
4767
4768 typedef volatile int SpinLockT;
4769
4770 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4771 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4772 return; // normal fast-path return
4773 }
4774
4775 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4776 int ctr = 0;
4777 int Yields = 0;
4778 for (;;) {
4779 while (*adr != 0) {
4780 ++ctr;
4781 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4782 if (Yields > 5) {
4783 os::naked_short_sleep(1);
4784 } else {
4785 os::naked_yield();
4786 ++Yields;
4787 }
4788 } else {
4789 SpinPause();
4790 }
4791 }
4792 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4793 }
4794 }
4795
4796 void Thread::SpinRelease(volatile int * adr) {
4797 assert(*adr != 0, "invariant");
4798 OrderAccess::fence(); // guarantee at least release consistency.
4799 // Roach-motel semantics.
4800 // It's safe if subsequent LDs and STs float "up" into the critical section,
4801 // but prior LDs and STs within the critical section can't be allowed
4802 // to reorder or float past the ST that releases the lock.
4803 // Loads and stores in the critical section - which appear in program
4804 // order before the store that releases the lock - must also appear
4805 // before the store that releases the lock in memory visibility order.
4806 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4807 // the ST of 0 into the lock-word which releases the lock, so fence
4808 // more than covers this on all platforms.
4809 *adr = 0;
4810 }
4811
4812 // muxAcquire and muxRelease:
4813 //
4814 // * muxAcquire and muxRelease support a single-word lock-word construct.
4815 // The LSB of the word is set IFF the lock is held.
4816 // The remainder of the word points to the head of a singly-linked list
4817 // of threads blocked on the lock.
4818 //
4819 // * The current implementation of muxAcquire-muxRelease uses its own
4820 // dedicated Thread._MuxEvent instance. If we're interested in
4821 // minimizing the peak number of extant ParkEvent instances then
4822 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4823 // as certain invariants were satisfied. Specifically, care would need
4824 // to be taken with regards to consuming unpark() "permits".
4825 // A safe rule of thumb is that a thread would never call muxAcquire()
4826 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4827 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4828 // consume an unpark() permit intended for monitorenter, for instance.
4829 // One way around this would be to widen the restricted-range semaphore
4830 // implemented in park(). Another alternative would be to provide
4831 // multiple instances of the PlatformEvent() for each thread. One
4832 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4833 //
4834 // * Usage:
4835 // -- Only as leaf locks
4836 // -- for short-term locking only as muxAcquire does not perform
4837 // thread state transitions.
4838 //
4839 // Alternatives:
4840 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4841 // but with parking or spin-then-park instead of pure spinning.
4842 // * Use Taura-Oyama-Yonenzawa locks.
4843 // * It's possible to construct a 1-0 lock if we encode the lockword as
4844 // (List,LockByte). Acquire will CAS the full lockword while Release
4845 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4846 // acquiring threads use timers (ParkTimed) to detect and recover from
4847 // the stranding window. Thread/Node structures must be aligned on 256-byte
4848 // boundaries by using placement-new.
4849 // * Augment MCS with advisory back-link fields maintained with CAS().
4850 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4851 // The validity of the backlinks must be ratified before we trust the value.
4852 // If the backlinks are invalid the exiting thread must back-track through the
4853 // the forward links, which are always trustworthy.
4854 // * Add a successor indication. The LockWord is currently encoded as
4855 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4856 // to provide the usual futile-wakeup optimization.
4857 // See RTStt for details.
4858 //
4859
4860
4861 const intptr_t LOCKBIT = 1;
4862
4863 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4864 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4865 if (w == 0) return;
4866 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4867 return;
4868 }
4869
4870 ParkEvent * const Self = Thread::current()->_MuxEvent;
4871 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4872 for (;;) {
4873 int its = (os::is_MP() ? 100 : 0) + 1;
4874
4875 // Optional spin phase: spin-then-park strategy
4876 while (--its >= 0) {
4877 w = *Lock;
4878 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4879 return;
4880 }
4881 }
4882
4883 Self->reset();
4884 Self->OnList = intptr_t(Lock);
4885 // The following fence() isn't _strictly necessary as the subsequent
4886 // CAS() both serializes execution and ratifies the fetched *Lock value.
4887 OrderAccess::fence();
4888 for (;;) {
4889 w = *Lock;
4890 if ((w & LOCKBIT) == 0) {
4891 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4892 Self->OnList = 0; // hygiene - allows stronger asserts
4893 return;
4894 }
4895 continue; // Interference -- *Lock changed -- Just retry
4896 }
4897 assert(w & LOCKBIT, "invariant");
4898 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4899 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4900 }
4901
4902 while (Self->OnList != 0) {
4903 Self->park();
4904 }
4905 }
4906 }
4907
4908 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4909 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4910 if (w == 0) return;
4911 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4912 return;
4913 }
4914
4915 ParkEvent * ReleaseAfter = NULL;
4916 if (ev == NULL) {
4917 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4918 }
4919 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4920 for (;;) {
4921 guarantee(ev->OnList == 0, "invariant");
4922 int its = (os::is_MP() ? 100 : 0) + 1;
4923
4924 // Optional spin phase: spin-then-park strategy
4925 while (--its >= 0) {
4926 w = *Lock;
4927 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4928 if (ReleaseAfter != NULL) {
4929 ParkEvent::Release(ReleaseAfter);
4930 }
4931 return;
4932 }
4933 }
4934
4935 ev->reset();
4936 ev->OnList = intptr_t(Lock);
4937 // The following fence() isn't _strictly necessary as the subsequent
4938 // CAS() both serializes execution and ratifies the fetched *Lock value.
4939 OrderAccess::fence();
4940 for (;;) {
4941 w = *Lock;
4942 if ((w & LOCKBIT) == 0) {
4943 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4944 ev->OnList = 0;
4945 // We call ::Release while holding the outer lock, thus
4946 // artificially lengthening the critical section.
4947 // Consider deferring the ::Release() until the subsequent unlock(),
4948 // after we've dropped the outer lock.
4949 if (ReleaseAfter != NULL) {
4950 ParkEvent::Release(ReleaseAfter);
4951 }
4952 return;
4953 }
4954 continue; // Interference -- *Lock changed -- Just retry
4955 }
4956 assert(w & LOCKBIT, "invariant");
4957 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4958 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4959 }
4960
4961 while (ev->OnList != 0) {
4962 ev->park();
4963 }
4964 }
4965 }
4966
4967 // Release() must extract a successor from the list and then wake that thread.
4968 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4969 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4970 // Release() would :
4971 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4972 // (B) Extract a successor from the private list "in-hand"
4973 // (C) attempt to CAS() the residual back into *Lock over null.
4974 // If there were any newly arrived threads and the CAS() would fail.
4975 // In that case Release() would detach the RATs, re-merge the list in-hand
4976 // with the RATs and repeat as needed. Alternately, Release() might
4977 // detach and extract a successor, but then pass the residual list to the wakee.
4978 // The wakee would be responsible for reattaching and remerging before it
4979 // competed for the lock.
4980 //
4981 // Both "pop" and DMR are immune from ABA corruption -- there can be
4982 // multiple concurrent pushers, but only one popper or detacher.
4983 // This implementation pops from the head of the list. This is unfair,
4984 // but tends to provide excellent throughput as hot threads remain hot.
4985 // (We wake recently run threads first).
4986 //
4987 // All paths through muxRelease() will execute a CAS.
4988 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4989 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4990 // executed within the critical section are complete and globally visible before the
4991 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4992 void Thread::muxRelease(volatile intptr_t * Lock) {
4993 for (;;) {
4994 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4995 assert(w & LOCKBIT, "invariant");
4996 if (w == LOCKBIT) return;
4997 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4998 assert(List != NULL, "invariant");
4999 assert(List->OnList == intptr_t(Lock), "invariant");
5000 ParkEvent * const nxt = List->ListNext;
5001 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5002
5003 // The following CAS() releases the lock and pops the head element.
5004 // The CAS() also ratifies the previously fetched lock-word value.
5005 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5006 continue;
5007 }
5008 List->OnList = 0;
5009 OrderAccess::fence();
5010 List->unpark();
5011 return;
5012 }
5013 }
5014
5015
5016 void Threads::verify() {
5017 ALL_JAVA_THREADS(p) {
5018 p->verify();
5019 }
5020 VMThread* thread = VMThread::vm_thread();
5021 if (thread != NULL) thread->verify();
5022 }