1 /* 2 * Copyright (c) 1997, 2018, 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 "classfile/classLoader.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/barrierSet.hpp" 37 #include "gc/shared/gcId.hpp" 38 #include "gc/shared/gcLocker.inline.hpp" 39 #include "gc/shared/workgroup.hpp" 40 #include "interpreter/interpreter.hpp" 41 #include "interpreter/linkResolver.hpp" 42 #include "interpreter/oopMapCache.hpp" 43 #include "jfr/jfrEvents.hpp" 44 #include "jfr/support/jfrThreadId.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 "prims/privilegedStack.hpp" 65 #include "runtime/arguments.hpp" 66 #include "runtime/atomic.hpp" 67 #include "runtime/biasedLocking.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/handshake.hpp" 74 #include "runtime/init.hpp" 75 #include "runtime/interfaceSupport.inline.hpp" 76 #include "runtime/java.hpp" 77 #include "runtime/javaCalls.hpp" 78 #include "runtime/jniHandles.inline.hpp" 79 #include "runtime/jniPeriodicChecker.hpp" 80 #include "runtime/memprofiler.hpp" 81 #include "runtime/mutexLocker.hpp" 82 #include "runtime/objectMonitor.hpp" 83 #include "runtime/orderAccess.hpp" 84 #include "runtime/osThread.hpp" 85 #include "runtime/prefetch.inline.hpp" 86 #include "runtime/safepoint.hpp" 87 #include "runtime/safepointMechanism.inline.hpp" 88 #include "runtime/sharedRuntime.hpp" 89 #include "runtime/statSampler.hpp" 90 #include "runtime/stubRoutines.hpp" 91 #include "runtime/sweeper.hpp" 92 #include "runtime/task.hpp" 93 #include "runtime/thread.inline.hpp" 94 #include "runtime/threadCritical.hpp" 95 #include "runtime/threadSMR.inline.hpp" 96 #include "runtime/timer.hpp" 97 #include "runtime/timerTrace.hpp" 98 #include "runtime/vframe.inline.hpp" 99 #include "runtime/vframeArray.hpp" 100 #include "runtime/vframe_hp.hpp" 101 #include "runtime/vmThread.hpp" 102 #include "runtime/vm_operations.hpp" 103 #include "runtime/vm_version.hpp" 104 #include "services/attachListener.hpp" 105 #include "services/management.hpp" 106 #include "services/memTracker.hpp" 107 #include "services/threadService.hpp" 108 #include "utilities/align.hpp" 109 #include "utilities/copy.hpp" 110 #include "utilities/defaultStream.hpp" 111 #include "utilities/dtrace.hpp" 112 #include "utilities/events.hpp" 113 #include "utilities/macros.hpp" 114 #include "utilities/preserveException.hpp" 115 #include "utilities/vmError.hpp" 116 #if INCLUDE_JVMCI 117 #include "jvmci/jvmciCompiler.hpp" 118 #include "jvmci/jvmciRuntime.hpp" 119 #include "logging/logHandle.hpp" 120 #endif 121 #ifdef COMPILER1 122 #include "c1/c1_Compiler.hpp" 123 #endif 124 #ifdef COMPILER2 125 #include "opto/c2compiler.hpp" 126 #include "opto/idealGraphPrinter.hpp" 127 #endif 128 #if INCLUDE_RTM_OPT 129 #include "runtime/rtmLocking.hpp" 130 #endif 131 #if INCLUDE_JFR 132 #include "jfr/jfr.hpp" 133 #endif 134 135 // Initialization after module runtime initialization 136 void universe_post_module_init(); // must happen after call_initPhase2 137 138 #ifdef DTRACE_ENABLED 139 140 // Only bother with this argument setup if dtrace is available 141 142 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 143 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 144 145 #define DTRACE_THREAD_PROBE(probe, javathread) \ 146 { \ 147 ResourceMark rm(this); \ 148 int len = 0; \ 149 const char* name = (javathread)->get_thread_name(); \ 150 len = strlen(name); \ 151 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 152 (char *) name, len, \ 153 java_lang_Thread::thread_id((javathread)->threadObj()), \ 154 (uintptr_t) (javathread)->osthread()->thread_id(), \ 155 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 156 } 157 158 #else // ndef DTRACE_ENABLED 159 160 #define DTRACE_THREAD_PROBE(probe, javathread) 161 162 #endif // ndef DTRACE_ENABLED 163 164 #ifndef USE_LIBRARY_BASED_TLS_ONLY 165 // Current thread is maintained as a thread-local variable 166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 167 #endif 168 // Class hierarchy 169 // - Thread 170 // - VMThread 171 // - WatcherThread 172 // - ConcurrentMarkSweepThread 173 // - JavaThread 174 // - CompilerThread 175 176 // ======= Thread ======== 177 // Support for forcing alignment of thread objects for biased locking 178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 179 if (UseBiasedLocking) { 180 const int alignment = markOopDesc::biased_lock_alignment; 181 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 182 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 183 : AllocateHeap(aligned_size, flags, CURRENT_PC, 184 AllocFailStrategy::RETURN_NULL); 185 void* aligned_addr = align_up(real_malloc_addr, alignment); 186 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 187 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 188 "JavaThread alignment code overflowed allocated storage"); 189 if (aligned_addr != real_malloc_addr) { 190 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 191 p2i(real_malloc_addr), 192 p2i(aligned_addr)); 193 } 194 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 195 return aligned_addr; 196 } else { 197 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 198 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 199 } 200 } 201 202 void Thread::operator delete(void* p) { 203 if (UseBiasedLocking) { 204 FreeHeap(((Thread*) p)->_real_malloc_address); 205 } else { 206 FreeHeap(p); 207 } 208 } 209 210 void JavaThread::smr_delete() { 211 if (_on_thread_list) { 212 ThreadsSMRSupport::smr_delete(this); 213 } else { 214 delete this; 215 } 216 } 217 218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 219 // JavaThread 220 221 222 Thread::Thread() { 223 // stack and get_thread 224 set_stack_base(NULL); 225 set_stack_size(0); 226 set_self_raw_id(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 240 // This initial value ==> never claimed. 241 _oops_do_parity = 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 debug_only(_allow_allocation_count = 0;) 253 NOT_PRODUCT(_allow_safepoint_count = 0;) 254 NOT_PRODUCT(_skip_gcalot = false;) 255 _jvmti_env_iteration_count = 0; 256 set_allocated_bytes(0); 257 _vm_operation_started_count = 0; 258 _vm_operation_completed_count = 0; 259 _current_pending_monitor = NULL; 260 _current_pending_monitor_is_from_java = true; 261 _current_waiting_monitor = NULL; 262 _num_nested_signal = 0; 263 omFreeList = NULL; 264 omFreeCount = 0; 265 omFreeProvision = 32; 266 omInUseList = NULL; 267 omInUseCount = 0; 268 269 #ifdef ASSERT 270 _visited_for_critical_count = false; 271 #endif 272 273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 274 Monitor::_safepoint_check_sometimes); 275 _suspend_flags = 0; 276 277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 278 _hashStateX = os::random(); 279 _hashStateY = 842502087; 280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 281 _hashStateW = 273326509; 282 283 _OnTrap = 0; 284 _schedctl = NULL; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _SleepEvent = ParkEvent::Allocate(this); 297 _MutexEvent = ParkEvent::Allocate(this); 298 _MuxEvent = ParkEvent::Allocate(this); 299 300 #ifdef CHECK_UNHANDLED_OOPS 301 if (CheckUnhandledOops) { 302 _unhandled_oops = new UnhandledOops(this); 303 } 304 #endif // CHECK_UNHANDLED_OOPS 305 #ifdef ASSERT 306 if (UseBiasedLocking) { 307 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 308 assert(this == _real_malloc_address || 309 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 310 "bug in forced alignment of thread objects"); 311 } 312 #endif // ASSERT 313 314 // Notify the barrier set that a thread is being created. Note that the 315 // main thread is created before a barrier set is available. The call to 316 // BarrierSet::on_thread_create() for the main thread is therefore deferred 317 // until it calls BarrierSet::set_barrier_set(). 318 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 319 if (barrier_set != NULL) { 320 barrier_set->on_thread_create(this); 321 } 322 } 323 324 void Thread::initialize_thread_current() { 325 #ifndef USE_LIBRARY_BASED_TLS_ONLY 326 assert(_thr_current == NULL, "Thread::current already initialized"); 327 _thr_current = this; 328 #endif 329 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 330 ThreadLocalStorage::set_thread(this); 331 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 332 } 333 334 void Thread::clear_thread_current() { 335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 336 #ifndef USE_LIBRARY_BASED_TLS_ONLY 337 _thr_current = NULL; 338 #endif 339 ThreadLocalStorage::set_thread(NULL); 340 } 341 342 void Thread::record_stack_base_and_size() { 343 set_stack_base(os::current_stack_base()); 344 set_stack_size(os::current_stack_size()); 345 // CR 7190089: on Solaris, primordial thread's stack is adjusted 346 // in initialize_thread(). Without the adjustment, stack size is 347 // incorrect if stack is set to unlimited (ulimit -s unlimited). 348 // So far, only Solaris has real implementation of initialize_thread(). 349 // 350 // set up any platform-specific state. 351 os::initialize_thread(this); 352 353 // Set stack limits after thread is initialized. 354 if (is_Java_thread()) { 355 ((JavaThread*) this)->set_stack_overflow_limit(); 356 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 357 } 358 #if INCLUDE_NMT 359 // record thread's native stack, stack grows downward 360 MemTracker::record_thread_stack(stack_end(), stack_size()); 361 #endif // INCLUDE_NMT 362 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 363 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 364 os::current_thread_id(), p2i(stack_base() - stack_size()), 365 p2i(stack_base()), stack_size()/1024); 366 } 367 368 369 Thread::~Thread() { 370 JFR_ONLY(Jfr::on_thread_destruct(this);) 371 372 // Notify the barrier set that a thread is being destroyed. Note that a barrier 373 // set might not be available if we encountered errors during bootstrapping. 374 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 375 if (barrier_set != NULL) { 376 barrier_set->on_thread_destroy(this); 377 } 378 379 380 // stack_base can be NULL if the thread is never started or exited before 381 // record_stack_base_and_size called. Although, we would like to ensure 382 // that all started threads do call record_stack_base_and_size(), there is 383 // not proper way to enforce that. 384 #if INCLUDE_NMT 385 if (_stack_base != NULL) { 386 MemTracker::release_thread_stack(stack_end(), stack_size()); 387 #ifdef ASSERT 388 set_stack_base(NULL); 389 #endif 390 } 391 #endif // INCLUDE_NMT 392 393 // deallocate data structures 394 delete resource_area(); 395 // since the handle marks are using the handle area, we have to deallocated the root 396 // handle mark before deallocating the thread's handle area, 397 assert(last_handle_mark() != NULL, "check we have an element"); 398 delete last_handle_mark(); 399 assert(last_handle_mark() == NULL, "check we have reached the end"); 400 401 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 402 // We NULL out the fields for good hygiene. 403 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 404 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 405 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 406 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 407 408 delete handle_area(); 409 delete metadata_handles(); 410 411 // SR_handler uses this as a termination indicator - 412 // needs to happen before os::free_thread() 413 delete _SR_lock; 414 _SR_lock = NULL; 415 416 // osthread() can be NULL, if creation of thread failed. 417 if (osthread() != NULL) os::free_thread(osthread()); 418 419 // clear Thread::current if thread is deleting itself. 420 // Needed to ensure JNI correctly detects non-attached threads. 421 if (this == Thread::current()) { 422 clear_thread_current(); 423 } 424 425 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 426 } 427 428 // NOTE: dummy function for assertion purpose. 429 void Thread::run() { 430 ShouldNotReachHere(); 431 } 432 433 #ifdef ASSERT 434 // A JavaThread is considered "dangling" if it is not the current 435 // thread, has been added the Threads list, the system is not at a 436 // safepoint and the Thread is not "protected". 437 // 438 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 439 assert(!thread->is_Java_thread() || Thread::current() == thread || 440 !((JavaThread *) thread)->on_thread_list() || 441 SafepointSynchronize::is_at_safepoint() || 442 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 443 "possibility of dangling Thread pointer"); 444 } 445 #endif 446 447 ThreadPriority Thread::get_priority(const Thread* const thread) { 448 ThreadPriority priority; 449 // Can return an error! 450 (void)os::get_priority(thread, priority); 451 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 452 return priority; 453 } 454 455 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 456 debug_only(check_for_dangling_thread_pointer(thread);) 457 // Can return an error! 458 (void)os::set_priority(thread, priority); 459 } 460 461 462 void Thread::start(Thread* thread) { 463 // Start is different from resume in that its safety is guaranteed by context or 464 // being called from a Java method synchronized on the Thread object. 465 if (!DisableStartThread) { 466 if (thread->is_Java_thread()) { 467 // Initialize the thread state to RUNNABLE before starting this thread. 468 // Can not set it after the thread started because we do not know the 469 // exact thread state at that time. It could be in MONITOR_WAIT or 470 // in SLEEPING or some other state. 471 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 472 java_lang_Thread::RUNNABLE); 473 } 474 os::start_thread(thread); 475 } 476 } 477 478 // Enqueue a VM_Operation to do the job for us - sometime later 479 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 480 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 481 VMThread::execute(vm_stop); 482 } 483 484 485 // Check if an external suspend request has completed (or has been 486 // cancelled). Returns true if the thread is externally suspended and 487 // false otherwise. 488 // 489 // The bits parameter returns information about the code path through 490 // the routine. Useful for debugging: 491 // 492 // set in is_ext_suspend_completed(): 493 // 0x00000001 - routine was entered 494 // 0x00000010 - routine return false at end 495 // 0x00000100 - thread exited (return false) 496 // 0x00000200 - suspend request cancelled (return false) 497 // 0x00000400 - thread suspended (return true) 498 // 0x00001000 - thread is in a suspend equivalent state (return true) 499 // 0x00002000 - thread is native and walkable (return true) 500 // 0x00004000 - thread is native_trans and walkable (needed retry) 501 // 502 // set in wait_for_ext_suspend_completion(): 503 // 0x00010000 - routine was entered 504 // 0x00020000 - suspend request cancelled before loop (return false) 505 // 0x00040000 - thread suspended before loop (return true) 506 // 0x00080000 - suspend request cancelled in loop (return false) 507 // 0x00100000 - thread suspended in loop (return true) 508 // 0x00200000 - suspend not completed during retry loop (return false) 509 510 // Helper class for tracing suspend wait debug bits. 511 // 512 // 0x00000100 indicates that the target thread exited before it could 513 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 514 // 0x00080000 each indicate a cancelled suspend request so they don't 515 // count as wait failures either. 516 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 517 518 class TraceSuspendDebugBits : public StackObj { 519 private: 520 JavaThread * jt; 521 bool is_wait; 522 bool called_by_wait; // meaningful when !is_wait 523 uint32_t * bits; 524 525 public: 526 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 527 uint32_t *_bits) { 528 jt = _jt; 529 is_wait = _is_wait; 530 called_by_wait = _called_by_wait; 531 bits = _bits; 532 } 533 534 ~TraceSuspendDebugBits() { 535 if (!is_wait) { 536 #if 1 537 // By default, don't trace bits for is_ext_suspend_completed() calls. 538 // That trace is very chatty. 539 return; 540 #else 541 if (!called_by_wait) { 542 // If tracing for is_ext_suspend_completed() is enabled, then only 543 // trace calls to it from wait_for_ext_suspend_completion() 544 return; 545 } 546 #endif 547 } 548 549 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 550 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 551 MutexLocker ml(Threads_lock); // needed for get_thread_name() 552 ResourceMark rm; 553 554 tty->print_cr( 555 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 556 jt->get_thread_name(), *bits); 557 558 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 559 } 560 } 561 } 562 }; 563 #undef DEBUG_FALSE_BITS 564 565 566 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 567 uint32_t *bits) { 568 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 569 570 bool did_trans_retry = false; // only do thread_in_native_trans retry once 571 bool do_trans_retry; // flag to force the retry 572 573 *bits |= 0x00000001; 574 575 do { 576 do_trans_retry = false; 577 578 if (is_exiting()) { 579 // Thread is in the process of exiting. This is always checked 580 // first to reduce the risk of dereferencing a freed JavaThread. 581 *bits |= 0x00000100; 582 return false; 583 } 584 585 if (!is_external_suspend()) { 586 // Suspend request is cancelled. This is always checked before 587 // is_ext_suspended() to reduce the risk of a rogue resume 588 // confusing the thread that made the suspend request. 589 *bits |= 0x00000200; 590 return false; 591 } 592 593 if (is_ext_suspended()) { 594 // thread is suspended 595 *bits |= 0x00000400; 596 return true; 597 } 598 599 // Now that we no longer do hard suspends of threads running 600 // native code, the target thread can be changing thread state 601 // while we are in this routine: 602 // 603 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 604 // 605 // We save a copy of the thread state as observed at this moment 606 // and make our decision about suspend completeness based on the 607 // copy. This closes the race where the thread state is seen as 608 // _thread_in_native_trans in the if-thread_blocked check, but is 609 // seen as _thread_blocked in if-thread_in_native_trans check. 610 JavaThreadState save_state = thread_state(); 611 612 if (save_state == _thread_blocked && is_suspend_equivalent()) { 613 // If the thread's state is _thread_blocked and this blocking 614 // condition is known to be equivalent to a suspend, then we can 615 // consider the thread to be externally suspended. This means that 616 // the code that sets _thread_blocked has been modified to do 617 // self-suspension if the blocking condition releases. We also 618 // used to check for CONDVAR_WAIT here, but that is now covered by 619 // the _thread_blocked with self-suspension check. 620 // 621 // Return true since we wouldn't be here unless there was still an 622 // external suspend request. 623 *bits |= 0x00001000; 624 return true; 625 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 626 // Threads running native code will self-suspend on native==>VM/Java 627 // transitions. If its stack is walkable (should always be the case 628 // unless this function is called before the actual java_suspend() 629 // call), then the wait is done. 630 *bits |= 0x00002000; 631 return true; 632 } else if (!called_by_wait && !did_trans_retry && 633 save_state == _thread_in_native_trans && 634 frame_anchor()->walkable()) { 635 // The thread is transitioning from thread_in_native to another 636 // thread state. check_safepoint_and_suspend_for_native_trans() 637 // will force the thread to self-suspend. If it hasn't gotten 638 // there yet we may have caught the thread in-between the native 639 // code check above and the self-suspend. Lucky us. If we were 640 // called by wait_for_ext_suspend_completion(), then it 641 // will be doing the retries so we don't have to. 642 // 643 // Since we use the saved thread state in the if-statement above, 644 // there is a chance that the thread has already transitioned to 645 // _thread_blocked by the time we get here. In that case, we will 646 // make a single unnecessary pass through the logic below. This 647 // doesn't hurt anything since we still do the trans retry. 648 649 *bits |= 0x00004000; 650 651 // Once the thread leaves thread_in_native_trans for another 652 // thread state, we break out of this retry loop. We shouldn't 653 // need this flag to prevent us from getting back here, but 654 // sometimes paranoia is good. 655 did_trans_retry = true; 656 657 // We wait for the thread to transition to a more usable state. 658 for (int i = 1; i <= SuspendRetryCount; i++) { 659 // We used to do an "os::yield_all(i)" call here with the intention 660 // that yielding would increase on each retry. However, the parameter 661 // is ignored on Linux which means the yield didn't scale up. Waiting 662 // on the SR_lock below provides a much more predictable scale up for 663 // the delay. It also provides a simple/direct point to check for any 664 // safepoint requests from the VMThread 665 666 // temporarily drops SR_lock while doing wait with safepoint check 667 // (if we're a JavaThread - the WatcherThread can also call this) 668 // and increase delay with each retry 669 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 670 671 // check the actual thread state instead of what we saved above 672 if (thread_state() != _thread_in_native_trans) { 673 // the thread has transitioned to another thread state so 674 // try all the checks (except this one) one more time. 675 do_trans_retry = true; 676 break; 677 } 678 } // end retry loop 679 680 681 } 682 } while (do_trans_retry); 683 684 *bits |= 0x00000010; 685 return false; 686 } 687 688 // Wait for an external suspend request to complete (or be cancelled). 689 // Returns true if the thread is externally suspended and false otherwise. 690 // 691 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 692 uint32_t *bits) { 693 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 694 false /* !called_by_wait */, bits); 695 696 // local flag copies to minimize SR_lock hold time 697 bool is_suspended; 698 bool pending; 699 uint32_t reset_bits; 700 701 // set a marker so is_ext_suspend_completed() knows we are the caller 702 *bits |= 0x00010000; 703 704 // We use reset_bits to reinitialize the bits value at the top of 705 // each retry loop. This allows the caller to make use of any 706 // unused bits for their own marking purposes. 707 reset_bits = *bits; 708 709 { 710 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 711 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 712 delay, bits); 713 pending = is_external_suspend(); 714 } 715 // must release SR_lock to allow suspension to complete 716 717 if (!pending) { 718 // A cancelled suspend request is the only false return from 719 // is_ext_suspend_completed() that keeps us from entering the 720 // retry loop. 721 *bits |= 0x00020000; 722 return false; 723 } 724 725 if (is_suspended) { 726 *bits |= 0x00040000; 727 return true; 728 } 729 730 for (int i = 1; i <= retries; i++) { 731 *bits = reset_bits; // reinit to only track last retry 732 733 // We used to do an "os::yield_all(i)" call here with the intention 734 // that yielding would increase on each retry. However, the parameter 735 // is ignored on Linux which means the yield didn't scale up. Waiting 736 // on the SR_lock below provides a much more predictable scale up for 737 // the delay. It also provides a simple/direct point to check for any 738 // safepoint requests from the VMThread 739 740 { 741 MutexLocker ml(SR_lock()); 742 // wait with safepoint check (if we're a JavaThread - the WatcherThread 743 // can also call this) and increase delay with each retry 744 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 745 746 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 747 delay, bits); 748 749 // It is possible for the external suspend request to be cancelled 750 // (by a resume) before the actual suspend operation is completed. 751 // Refresh our local copy to see if we still need to wait. 752 pending = is_external_suspend(); 753 } 754 755 if (!pending) { 756 // A cancelled suspend request is the only false return from 757 // is_ext_suspend_completed() that keeps us from staying in the 758 // retry loop. 759 *bits |= 0x00080000; 760 return false; 761 } 762 763 if (is_suspended) { 764 *bits |= 0x00100000; 765 return true; 766 } 767 } // end retry loop 768 769 // thread did not suspend after all our retries 770 *bits |= 0x00200000; 771 return false; 772 } 773 774 // Called from API entry points which perform stack walking. If the 775 // associated JavaThread is the current thread, then wait_for_suspend 776 // is not used. Otherwise, it determines if we should wait for the 777 // "other" thread to complete external suspension. (NOTE: in future 778 // releases the suspension mechanism should be reimplemented so this 779 // is not necessary.) 780 // 781 bool 782 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 783 if (this != JavaThread::current()) { 784 // "other" threads require special handling. 785 if (wait_for_suspend) { 786 // We are allowed to wait for the external suspend to complete 787 // so give the other thread a chance to get suspended. 788 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 789 SuspendRetryDelay, bits)) { 790 // Didn't make it so let the caller know. 791 return false; 792 } 793 } 794 // We aren't allowed to wait for the external suspend to complete 795 // so if the other thread isn't externally suspended we need to 796 // let the caller know. 797 else if (!is_ext_suspend_completed_with_lock(bits)) { 798 return false; 799 } 800 } 801 802 return true; 803 } 804 805 #ifndef PRODUCT 806 void JavaThread::record_jump(address target, address instr, const char* file, 807 int line) { 808 809 // This should not need to be atomic as the only way for simultaneous 810 // updates is via interrupts. Even then this should be rare or non-existent 811 // and we don't care that much anyway. 812 813 int index = _jmp_ring_index; 814 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 815 _jmp_ring[index]._target = (intptr_t) target; 816 _jmp_ring[index]._instruction = (intptr_t) instr; 817 _jmp_ring[index]._file = file; 818 _jmp_ring[index]._line = line; 819 } 820 #endif // PRODUCT 821 822 void Thread::interrupt(Thread* thread) { 823 debug_only(check_for_dangling_thread_pointer(thread);) 824 os::interrupt(thread); 825 } 826 827 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 828 debug_only(check_for_dangling_thread_pointer(thread);) 829 // Note: If clear_interrupted==false, this simply fetches and 830 // returns the value of the field osthread()->interrupted(). 831 return os::is_interrupted(thread, clear_interrupted); 832 } 833 834 835 // GC Support 836 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 837 int thread_parity = _oops_do_parity; 838 if (thread_parity != strong_roots_parity) { 839 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 840 if (res == thread_parity) { 841 return true; 842 } else { 843 guarantee(res == strong_roots_parity, "Or else what?"); 844 return false; 845 } 846 } 847 return false; 848 } 849 850 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 851 active_handles()->oops_do(f); 852 // Do oop for ThreadShadow 853 f->do_oop((oop*)&_pending_exception); 854 handle_area()->oops_do(f); 855 856 if (MonitorInUseLists) { 857 // When using thread local monitor lists, we scan them here, 858 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 859 ObjectSynchronizer::thread_local_used_oops_do(this, f); 860 } 861 } 862 863 void Thread::metadata_handles_do(void f(Metadata*)) { 864 // Only walk the Handles in Thread. 865 if (metadata_handles() != NULL) { 866 for (int i = 0; i< metadata_handles()->length(); i++) { 867 f(metadata_handles()->at(i)); 868 } 869 } 870 } 871 872 void Thread::print_on(outputStream* st) const { 873 // get_priority assumes osthread initialized 874 if (osthread() != NULL) { 875 int os_prio; 876 if (os::get_native_priority(this, &os_prio) == OS_OK) { 877 st->print("os_prio=%d ", os_prio); 878 } 879 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 880 osthread()->print_on(st); 881 } 882 ThreadsSMRSupport::print_info_on(this, st); 883 st->print(" "); 884 debug_only(if (WizardMode) print_owned_locks_on(st);) 885 } 886 887 // Thread::print_on_error() is called by fatal error handler. Don't use 888 // any lock or allocate memory. 889 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 890 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 891 892 if (is_VM_thread()) { st->print("VMThread"); } 893 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 894 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 895 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 896 else { st->print("Thread"); } 897 898 if (is_Named_thread()) { 899 st->print(" \"%s\"", name()); 900 } 901 902 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 903 p2i(stack_end()), p2i(stack_base())); 904 905 if (osthread()) { 906 st->print(" [id=%d]", osthread()->thread_id()); 907 } 908 909 ThreadsSMRSupport::print_info_on(this, st); 910 } 911 912 void Thread::print_value_on(outputStream* st) const { 913 if (is_Named_thread()) { 914 st->print(" \"%s\" ", name()); 915 } 916 st->print(INTPTR_FORMAT, p2i(this)); // print address 917 } 918 919 #ifdef ASSERT 920 void Thread::print_owned_locks_on(outputStream* st) const { 921 Monitor *cur = _owned_locks; 922 if (cur == NULL) { 923 st->print(" (no locks) "); 924 } else { 925 st->print_cr(" Locks owned:"); 926 while (cur) { 927 cur->print_on(st); 928 cur = cur->next(); 929 } 930 } 931 } 932 933 static int ref_use_count = 0; 934 935 bool Thread::owns_locks_but_compiled_lock() const { 936 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 937 if (cur != Compile_lock) return true; 938 } 939 return false; 940 } 941 942 943 #endif 944 945 #ifndef PRODUCT 946 947 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 948 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 949 // no threads which allow_vm_block's are held 950 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 951 // Check if current thread is allowed to block at a safepoint 952 if (!(_allow_safepoint_count == 0)) { 953 fatal("Possible safepoint reached by thread that does not allow it"); 954 } 955 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 956 fatal("LEAF method calling lock?"); 957 } 958 959 #ifdef ASSERT 960 if (potential_vm_operation && is_Java_thread() 961 && !Universe::is_bootstrapping()) { 962 // Make sure we do not hold any locks that the VM thread also uses. 963 // This could potentially lead to deadlocks 964 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 965 // Threads_lock is special, since the safepoint synchronization will not start before this is 966 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 967 // since it is used to transfer control between JavaThreads and the VMThread 968 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 969 if ((cur->allow_vm_block() && 970 cur != Threads_lock && 971 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 972 cur != VMOperationRequest_lock && 973 cur != VMOperationQueue_lock) || 974 cur->rank() == Mutex::special) { 975 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 976 } 977 } 978 } 979 980 if (GCALotAtAllSafepoints) { 981 // We could enter a safepoint here and thus have a gc 982 InterfaceSupport::check_gc_alot(); 983 } 984 #endif 985 } 986 #endif 987 988 bool Thread::is_in_stack(address adr) const { 989 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 990 address end = os::current_stack_pointer(); 991 // Allow non Java threads to call this without stack_base 992 if (_stack_base == NULL) return true; 993 if (stack_base() >= adr && adr >= end) return true; 994 995 return false; 996 } 997 998 bool Thread::is_in_usable_stack(address adr) const { 999 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1000 size_t usable_stack_size = _stack_size - stack_guard_size; 1001 1002 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1003 } 1004 1005 1006 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1007 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1008 // used for compilation in the future. If that change is made, the need for these methods 1009 // should be revisited, and they should be removed if possible. 1010 1011 bool Thread::is_lock_owned(address adr) const { 1012 return on_local_stack(adr); 1013 } 1014 1015 bool Thread::set_as_starting_thread() { 1016 // NOTE: this must be called inside the main thread. 1017 return os::create_main_thread((JavaThread*)this); 1018 } 1019 1020 static void initialize_class(Symbol* class_name, TRAPS) { 1021 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1022 InstanceKlass::cast(klass)->initialize(CHECK); 1023 } 1024 1025 1026 // Creates the initial ThreadGroup 1027 static Handle create_initial_thread_group(TRAPS) { 1028 Handle system_instance = JavaCalls::construct_new_instance( 1029 SystemDictionary::ThreadGroup_klass(), 1030 vmSymbols::void_method_signature(), 1031 CHECK_NH); 1032 Universe::set_system_thread_group(system_instance()); 1033 1034 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1035 Handle main_instance = JavaCalls::construct_new_instance( 1036 SystemDictionary::ThreadGroup_klass(), 1037 vmSymbols::threadgroup_string_void_signature(), 1038 system_instance, 1039 string, 1040 CHECK_NH); 1041 return main_instance; 1042 } 1043 1044 // Creates the initial Thread 1045 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1046 TRAPS) { 1047 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1048 assert(ik->is_initialized(), "must be"); 1049 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1050 1051 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1052 // constructor calls Thread.current(), which must be set here for the 1053 // initial thread. 1054 java_lang_Thread::set_thread(thread_oop(), thread); 1055 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1056 thread->set_threadObj(thread_oop()); 1057 1058 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1059 1060 JavaValue result(T_VOID); 1061 JavaCalls::call_special(&result, thread_oop, 1062 ik, 1063 vmSymbols::object_initializer_name(), 1064 vmSymbols::threadgroup_string_void_signature(), 1065 thread_group, 1066 string, 1067 CHECK_NULL); 1068 return thread_oop(); 1069 } 1070 1071 char java_runtime_name[128] = ""; 1072 char java_runtime_version[128] = ""; 1073 1074 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1075 static const char* get_java_runtime_name(TRAPS) { 1076 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1077 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1078 fieldDescriptor fd; 1079 bool found = k != NULL && 1080 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1081 vmSymbols::string_signature(), &fd); 1082 if (found) { 1083 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1084 if (name_oop == NULL) { 1085 return NULL; 1086 } 1087 const char* name = java_lang_String::as_utf8_string(name_oop, 1088 java_runtime_name, 1089 sizeof(java_runtime_name)); 1090 return name; 1091 } else { 1092 return NULL; 1093 } 1094 } 1095 1096 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1097 static const char* get_java_runtime_version(TRAPS) { 1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1100 fieldDescriptor fd; 1101 bool found = k != NULL && 1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1103 vmSymbols::string_signature(), &fd); 1104 if (found) { 1105 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1106 if (name_oop == NULL) { 1107 return NULL; 1108 } 1109 const char* name = java_lang_String::as_utf8_string(name_oop, 1110 java_runtime_version, 1111 sizeof(java_runtime_version)); 1112 return name; 1113 } else { 1114 return NULL; 1115 } 1116 } 1117 1118 // General purpose hook into Java code, run once when the VM is initialized. 1119 // The Java library method itself may be changed independently from the VM. 1120 static void call_postVMInitHook(TRAPS) { 1121 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1122 if (klass != NULL) { 1123 JavaValue result(T_VOID); 1124 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1125 vmSymbols::void_method_signature(), 1126 CHECK); 1127 } 1128 } 1129 1130 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1131 bool daemon, TRAPS) { 1132 assert(thread_group.not_null(), "thread group should be specified"); 1133 assert(threadObj() == NULL, "should only create Java thread object once"); 1134 1135 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1136 assert(ik->is_initialized(), "must be"); 1137 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1138 1139 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1140 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1141 // constructor calls Thread.current(), which must be set here. 1142 java_lang_Thread::set_thread(thread_oop(), this); 1143 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1144 set_threadObj(thread_oop()); 1145 1146 JavaValue result(T_VOID); 1147 if (thread_name != NULL) { 1148 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1149 // Thread gets assigned specified name and null target 1150 JavaCalls::call_special(&result, 1151 thread_oop, 1152 ik, 1153 vmSymbols::object_initializer_name(), 1154 vmSymbols::threadgroup_string_void_signature(), 1155 thread_group, 1156 name, 1157 THREAD); 1158 } else { 1159 // Thread gets assigned name "Thread-nnn" and null target 1160 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1161 JavaCalls::call_special(&result, 1162 thread_oop, 1163 ik, 1164 vmSymbols::object_initializer_name(), 1165 vmSymbols::threadgroup_runnable_void_signature(), 1166 thread_group, 1167 Handle(), 1168 THREAD); 1169 } 1170 1171 1172 if (daemon) { 1173 java_lang_Thread::set_daemon(thread_oop()); 1174 } 1175 1176 if (HAS_PENDING_EXCEPTION) { 1177 return; 1178 } 1179 1180 Klass* group = SystemDictionary::ThreadGroup_klass(); 1181 Handle threadObj(THREAD, this->threadObj()); 1182 1183 JavaCalls::call_special(&result, 1184 thread_group, 1185 group, 1186 vmSymbols::add_method_name(), 1187 vmSymbols::thread_void_signature(), 1188 threadObj, // Arg 1 1189 THREAD); 1190 } 1191 1192 // NamedThread -- non-JavaThread subclasses with multiple 1193 // uniquely named instances should derive from this. 1194 NamedThread::NamedThread() : Thread() { 1195 _name = NULL; 1196 _processed_thread = NULL; 1197 _gc_id = GCId::undefined(); 1198 } 1199 1200 NamedThread::~NamedThread() { 1201 if (_name != NULL) { 1202 FREE_C_HEAP_ARRAY(char, _name); 1203 _name = NULL; 1204 } 1205 } 1206 1207 void NamedThread::set_name(const char* format, ...) { 1208 guarantee(_name == NULL, "Only get to set name once."); 1209 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1210 guarantee(_name != NULL, "alloc failure"); 1211 va_list ap; 1212 va_start(ap, format); 1213 jio_vsnprintf(_name, max_name_len, format, ap); 1214 va_end(ap); 1215 } 1216 1217 void NamedThread::initialize_named_thread() { 1218 set_native_thread_name(name()); 1219 } 1220 1221 void NamedThread::print_on(outputStream* st) const { 1222 st->print("\"%s\" ", name()); 1223 Thread::print_on(st); 1224 st->cr(); 1225 } 1226 1227 1228 // ======= WatcherThread ======== 1229 1230 // The watcher thread exists to simulate timer interrupts. It should 1231 // be replaced by an abstraction over whatever native support for 1232 // timer interrupts exists on the platform. 1233 1234 WatcherThread* WatcherThread::_watcher_thread = NULL; 1235 bool WatcherThread::_startable = false; 1236 volatile bool WatcherThread::_should_terminate = false; 1237 1238 WatcherThread::WatcherThread() : Thread() { 1239 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1240 if (os::create_thread(this, os::watcher_thread)) { 1241 _watcher_thread = this; 1242 1243 // Set the watcher thread to the highest OS priority which should not be 1244 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1245 // is created. The only normal thread using this priority is the reference 1246 // handler thread, which runs for very short intervals only. 1247 // If the VMThread's priority is not lower than the WatcherThread profiling 1248 // will be inaccurate. 1249 os::set_priority(this, MaxPriority); 1250 if (!DisableStartThread) { 1251 os::start_thread(this); 1252 } 1253 } 1254 } 1255 1256 int WatcherThread::sleep() const { 1257 // The WatcherThread does not participate in the safepoint protocol 1258 // for the PeriodicTask_lock because it is not a JavaThread. 1259 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1260 1261 if (_should_terminate) { 1262 // check for termination before we do any housekeeping or wait 1263 return 0; // we did not sleep. 1264 } 1265 1266 // remaining will be zero if there are no tasks, 1267 // causing the WatcherThread to sleep until a task is 1268 // enrolled 1269 int remaining = PeriodicTask::time_to_wait(); 1270 int time_slept = 0; 1271 1272 // we expect this to timeout - we only ever get unparked when 1273 // we should terminate or when a new task has been enrolled 1274 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1275 1276 jlong time_before_loop = os::javaTimeNanos(); 1277 1278 while (true) { 1279 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1280 remaining); 1281 jlong now = os::javaTimeNanos(); 1282 1283 if (remaining == 0) { 1284 // if we didn't have any tasks we could have waited for a long time 1285 // consider the time_slept zero and reset time_before_loop 1286 time_slept = 0; 1287 time_before_loop = now; 1288 } else { 1289 // need to recalculate since we might have new tasks in _tasks 1290 time_slept = (int) ((now - time_before_loop) / 1000000); 1291 } 1292 1293 // Change to task list or spurious wakeup of some kind 1294 if (timedout || _should_terminate) { 1295 break; 1296 } 1297 1298 remaining = PeriodicTask::time_to_wait(); 1299 if (remaining == 0) { 1300 // Last task was just disenrolled so loop around and wait until 1301 // another task gets enrolled 1302 continue; 1303 } 1304 1305 remaining -= time_slept; 1306 if (remaining <= 0) { 1307 break; 1308 } 1309 } 1310 1311 return time_slept; 1312 } 1313 1314 void WatcherThread::run() { 1315 assert(this == watcher_thread(), "just checking"); 1316 1317 this->record_stack_base_and_size(); 1318 this->set_native_thread_name(this->name()); 1319 this->set_active_handles(JNIHandleBlock::allocate_block()); 1320 while (true) { 1321 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1322 assert(watcher_thread() == this, "thread consistency check"); 1323 1324 // Calculate how long it'll be until the next PeriodicTask work 1325 // should be done, and sleep that amount of time. 1326 int time_waited = sleep(); 1327 1328 if (VMError::is_error_reported()) { 1329 // A fatal error has happened, the error handler(VMError::report_and_die) 1330 // should abort JVM after creating an error log file. However in some 1331 // rare cases, the error handler itself might deadlock. Here periodically 1332 // check for error reporting timeouts, and if it happens, just proceed to 1333 // abort the VM. 1334 1335 // This code is in WatcherThread because WatcherThread wakes up 1336 // periodically so the fatal error handler doesn't need to do anything; 1337 // also because the WatcherThread is less likely to crash than other 1338 // threads. 1339 1340 for (;;) { 1341 // Note: we use naked sleep in this loop because we want to avoid using 1342 // any kind of VM infrastructure which may be broken at this point. 1343 if (VMError::check_timeout()) { 1344 // We hit error reporting timeout. Error reporting was interrupted and 1345 // will be wrapping things up now (closing files etc). Give it some more 1346 // time, then quit the VM. 1347 os::naked_short_sleep(200); 1348 // Print a message to stderr. 1349 fdStream err(defaultStream::output_fd()); 1350 err.print_raw_cr("# [ timer expired, abort... ]"); 1351 // skip atexit/vm_exit/vm_abort hooks 1352 os::die(); 1353 } 1354 1355 // Wait a second, then recheck for timeout. 1356 os::naked_short_sleep(999); 1357 } 1358 } 1359 1360 if (_should_terminate) { 1361 // check for termination before posting the next tick 1362 break; 1363 } 1364 1365 PeriodicTask::real_time_tick(time_waited); 1366 } 1367 1368 // Signal that it is terminated 1369 { 1370 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1371 _watcher_thread = NULL; 1372 Terminator_lock->notify(); 1373 } 1374 } 1375 1376 void WatcherThread::start() { 1377 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1378 1379 if (watcher_thread() == NULL && _startable) { 1380 _should_terminate = false; 1381 // Create the single instance of WatcherThread 1382 new WatcherThread(); 1383 } 1384 } 1385 1386 void WatcherThread::make_startable() { 1387 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1388 _startable = true; 1389 } 1390 1391 void WatcherThread::stop() { 1392 { 1393 // Follow normal safepoint aware lock enter protocol since the 1394 // WatcherThread is stopped by another JavaThread. 1395 MutexLocker ml(PeriodicTask_lock); 1396 _should_terminate = true; 1397 1398 WatcherThread* watcher = watcher_thread(); 1399 if (watcher != NULL) { 1400 // unpark the WatcherThread so it can see that it should terminate 1401 watcher->unpark(); 1402 } 1403 } 1404 1405 MutexLocker mu(Terminator_lock); 1406 1407 while (watcher_thread() != NULL) { 1408 // This wait should make safepoint checks, wait without a timeout, 1409 // and wait as a suspend-equivalent condition. 1410 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1411 Mutex::_as_suspend_equivalent_flag); 1412 } 1413 } 1414 1415 void WatcherThread::unpark() { 1416 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1417 PeriodicTask_lock->notify(); 1418 } 1419 1420 void WatcherThread::print_on(outputStream* st) const { 1421 st->print("\"%s\" ", name()); 1422 Thread::print_on(st); 1423 st->cr(); 1424 } 1425 1426 // ======= JavaThread ======== 1427 1428 #if INCLUDE_JVMCI 1429 1430 jlong* JavaThread::_jvmci_old_thread_counters; 1431 1432 bool jvmci_counters_include(JavaThread* thread) { 1433 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1434 } 1435 1436 void JavaThread::collect_counters(typeArrayOop array) { 1437 if (JVMCICounterSize > 0) { 1438 JavaThreadIteratorWithHandle jtiwh; 1439 for (int i = 0; i < array->length(); i++) { 1440 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1441 } 1442 for (; JavaThread *tp = jtiwh.next(); ) { 1443 if (jvmci_counters_include(tp)) { 1444 for (int i = 0; i < array->length(); i++) { 1445 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1446 } 1447 } 1448 } 1449 } 1450 } 1451 1452 #endif // INCLUDE_JVMCI 1453 1454 // A JavaThread is a normal Java thread 1455 1456 void JavaThread::initialize() { 1457 // Initialize fields 1458 1459 set_saved_exception_pc(NULL); 1460 set_threadObj(NULL); 1461 _anchor.clear(); 1462 set_entry_point(NULL); 1463 set_jni_functions(jni_functions()); 1464 set_callee_target(NULL); 1465 set_vm_result(NULL); 1466 set_vm_result_2(NULL); 1467 set_vframe_array_head(NULL); 1468 set_vframe_array_last(NULL); 1469 set_deferred_locals(NULL); 1470 set_deopt_mark(NULL); 1471 set_deopt_compiled_method(NULL); 1472 clear_must_deopt_id(); 1473 set_monitor_chunks(NULL); 1474 set_next(NULL); 1475 _on_thread_list = false; 1476 set_thread_state(_thread_new); 1477 _terminated = _not_terminated; 1478 _privileged_stack_top = NULL; 1479 _array_for_gc = NULL; 1480 _suspend_equivalent = false; 1481 _in_deopt_handler = 0; 1482 _doing_unsafe_access = false; 1483 _stack_guard_state = stack_guard_unused; 1484 #if INCLUDE_JVMCI 1485 _pending_monitorenter = false; 1486 _pending_deoptimization = -1; 1487 _pending_failed_speculation = NULL; 1488 _pending_transfer_to_interpreter = false; 1489 _adjusting_comp_level = false; 1490 _jvmci._alternate_call_target = NULL; 1491 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1492 if (JVMCICounterSize > 0) { 1493 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1494 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1495 } else { 1496 _jvmci_counters = NULL; 1497 } 1498 #endif // INCLUDE_JVMCI 1499 _reserved_stack_activation = NULL; // stack base not known yet 1500 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1501 _exception_pc = 0; 1502 _exception_handler_pc = 0; 1503 _is_method_handle_return = 0; 1504 _jvmti_thread_state= NULL; 1505 _should_post_on_exceptions_flag = JNI_FALSE; 1506 _jvmti_get_loaded_classes_closure = NULL; 1507 _interp_only_mode = 0; 1508 _special_runtime_exit_condition = _no_async_condition; 1509 _pending_async_exception = NULL; 1510 _thread_stat = NULL; 1511 _thread_stat = new ThreadStatistics(); 1512 _blocked_on_compilation = false; 1513 _jni_active_critical = 0; 1514 _pending_jni_exception_check_fn = NULL; 1515 _do_not_unlock_if_synchronized = false; 1516 _cached_monitor_info = NULL; 1517 _parker = Parker::Allocate(this); 1518 1519 #ifndef PRODUCT 1520 _jmp_ring_index = 0; 1521 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1522 record_jump(NULL, NULL, NULL, 0); 1523 } 1524 #endif // PRODUCT 1525 1526 // Setup safepoint state info for this thread 1527 ThreadSafepointState::create(this); 1528 1529 debug_only(_java_call_counter = 0); 1530 1531 // JVMTI PopFrame support 1532 _popframe_condition = popframe_inactive; 1533 _popframe_preserved_args = NULL; 1534 _popframe_preserved_args_size = 0; 1535 _frames_to_pop_failed_realloc = 0; 1536 1537 if (SafepointMechanism::uses_thread_local_poll()) { 1538 SafepointMechanism::initialize_header(this); 1539 } 1540 1541 pd_initialize(); 1542 } 1543 1544 JavaThread::JavaThread(bool is_attaching_via_jni) : 1545 Thread() { 1546 initialize(); 1547 if (is_attaching_via_jni) { 1548 _jni_attach_state = _attaching_via_jni; 1549 } else { 1550 _jni_attach_state = _not_attaching_via_jni; 1551 } 1552 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1553 } 1554 1555 bool JavaThread::reguard_stack(address cur_sp) { 1556 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1557 && _stack_guard_state != stack_guard_reserved_disabled) { 1558 return true; // Stack already guarded or guard pages not needed. 1559 } 1560 1561 if (register_stack_overflow()) { 1562 // For those architectures which have separate register and 1563 // memory stacks, we must check the register stack to see if 1564 // it has overflowed. 1565 return false; 1566 } 1567 1568 // Java code never executes within the yellow zone: the latter is only 1569 // there to provoke an exception during stack banging. If java code 1570 // is executing there, either StackShadowPages should be larger, or 1571 // some exception code in c1, c2 or the interpreter isn't unwinding 1572 // when it should. 1573 guarantee(cur_sp > stack_reserved_zone_base(), 1574 "not enough space to reguard - increase StackShadowPages"); 1575 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1576 enable_stack_yellow_reserved_zone(); 1577 if (reserved_stack_activation() != stack_base()) { 1578 set_reserved_stack_activation(stack_base()); 1579 } 1580 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1581 set_reserved_stack_activation(stack_base()); 1582 enable_stack_reserved_zone(); 1583 } 1584 return true; 1585 } 1586 1587 bool JavaThread::reguard_stack(void) { 1588 return reguard_stack(os::current_stack_pointer()); 1589 } 1590 1591 1592 void JavaThread::block_if_vm_exited() { 1593 if (_terminated == _vm_exited) { 1594 // _vm_exited is set at safepoint, and Threads_lock is never released 1595 // we will block here forever 1596 Threads_lock->lock_without_safepoint_check(); 1597 ShouldNotReachHere(); 1598 } 1599 } 1600 1601 1602 // Remove this ifdef when C1 is ported to the compiler interface. 1603 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1604 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1605 1606 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1607 Thread() { 1608 initialize(); 1609 _jni_attach_state = _not_attaching_via_jni; 1610 set_entry_point(entry_point); 1611 // Create the native thread itself. 1612 // %note runtime_23 1613 os::ThreadType thr_type = os::java_thread; 1614 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1615 os::java_thread; 1616 os::create_thread(this, thr_type, stack_sz); 1617 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1618 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1619 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1620 // the exception consists of creating the exception object & initializing it, initialization 1621 // will leave the VM via a JavaCall and then all locks must be unlocked). 1622 // 1623 // The thread is still suspended when we reach here. Thread must be explicit started 1624 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1625 // by calling Threads:add. The reason why this is not done here, is because the thread 1626 // object must be fully initialized (take a look at JVM_Start) 1627 } 1628 1629 JavaThread::~JavaThread() { 1630 1631 // JSR166 -- return the parker to the free list 1632 Parker::Release(_parker); 1633 _parker = NULL; 1634 1635 // Free any remaining previous UnrollBlock 1636 vframeArray* old_array = vframe_array_last(); 1637 1638 if (old_array != NULL) { 1639 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1640 old_array->set_unroll_block(NULL); 1641 delete old_info; 1642 delete old_array; 1643 } 1644 1645 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1646 if (deferred != NULL) { 1647 // This can only happen if thread is destroyed before deoptimization occurs. 1648 assert(deferred->length() != 0, "empty array!"); 1649 do { 1650 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1651 deferred->remove_at(0); 1652 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1653 delete dlv; 1654 } while (deferred->length() != 0); 1655 delete deferred; 1656 } 1657 1658 // All Java related clean up happens in exit 1659 ThreadSafepointState::destroy(this); 1660 if (_thread_stat != NULL) delete _thread_stat; 1661 1662 #if INCLUDE_JVMCI 1663 if (JVMCICounterSize > 0) { 1664 if (jvmci_counters_include(this)) { 1665 for (int i = 0; i < JVMCICounterSize; i++) { 1666 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1667 } 1668 } 1669 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1670 } 1671 #endif // INCLUDE_JVMCI 1672 } 1673 1674 1675 // The first routine called by a new Java thread 1676 void JavaThread::run() { 1677 // initialize thread-local alloc buffer related fields 1678 this->initialize_tlab(); 1679 1680 // used to test validity of stack trace backs 1681 this->record_base_of_stack_pointer(); 1682 1683 // Record real stack base and size. 1684 this->record_stack_base_and_size(); 1685 1686 this->create_stack_guard_pages(); 1687 1688 this->cache_global_variables(); 1689 1690 // Thread is now sufficient initialized to be handled by the safepoint code as being 1691 // in the VM. Change thread state from _thread_new to _thread_in_vm 1692 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1693 1694 assert(JavaThread::current() == this, "sanity check"); 1695 assert(!Thread::current()->owns_locks(), "sanity check"); 1696 1697 DTRACE_THREAD_PROBE(start, this); 1698 1699 // This operation might block. We call that after all safepoint checks for a new thread has 1700 // been completed. 1701 this->set_active_handles(JNIHandleBlock::allocate_block()); 1702 1703 if (JvmtiExport::should_post_thread_life()) { 1704 JvmtiExport::post_thread_start(this); 1705 } 1706 1707 EventThreadStart event; 1708 if (event.should_commit()) { 1709 event.set_thread(JFR_THREAD_ID(this)); 1710 event.commit(); 1711 } 1712 1713 // We call another function to do the rest so we are sure that the stack addresses used 1714 // from there will be lower than the stack base just computed 1715 thread_main_inner(); 1716 1717 // Note, thread is no longer valid at this point! 1718 } 1719 1720 1721 void JavaThread::thread_main_inner() { 1722 assert(JavaThread::current() == this, "sanity check"); 1723 assert(this->threadObj() != NULL, "just checking"); 1724 1725 // Execute thread entry point unless this thread has a pending exception 1726 // or has been stopped before starting. 1727 // Note: Due to JVM_StopThread we can have pending exceptions already! 1728 if (!this->has_pending_exception() && 1729 !java_lang_Thread::is_stillborn(this->threadObj())) { 1730 { 1731 ResourceMark rm(this); 1732 this->set_native_thread_name(this->get_thread_name()); 1733 } 1734 HandleMark hm(this); 1735 this->entry_point()(this, this); 1736 } 1737 1738 DTRACE_THREAD_PROBE(stop, this); 1739 1740 this->exit(false); 1741 this->smr_delete(); 1742 } 1743 1744 1745 static void ensure_join(JavaThread* thread) { 1746 // We do not need to grab the Threads_lock, since we are operating on ourself. 1747 Handle threadObj(thread, thread->threadObj()); 1748 assert(threadObj.not_null(), "java thread object must exist"); 1749 ObjectLocker lock(threadObj, thread); 1750 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1751 thread->clear_pending_exception(); 1752 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1753 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1754 // Clear the native thread instance - this makes isAlive return false and allows the join() 1755 // to complete once we've done the notify_all below 1756 java_lang_Thread::set_thread(threadObj(), NULL); 1757 lock.notify_all(thread); 1758 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1759 thread->clear_pending_exception(); 1760 } 1761 1762 1763 // For any new cleanup additions, please check to see if they need to be applied to 1764 // cleanup_failed_attach_current_thread as well. 1765 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1766 assert(this == JavaThread::current(), "thread consistency check"); 1767 1768 elapsedTimer _timer_exit_phase1; 1769 elapsedTimer _timer_exit_phase2; 1770 elapsedTimer _timer_exit_phase3; 1771 elapsedTimer _timer_exit_phase4; 1772 1773 if (log_is_enabled(Debug, os, thread, timer)) { 1774 _timer_exit_phase1.start(); 1775 } 1776 1777 HandleMark hm(this); 1778 Handle uncaught_exception(this, this->pending_exception()); 1779 this->clear_pending_exception(); 1780 Handle threadObj(this, this->threadObj()); 1781 assert(threadObj.not_null(), "Java thread object should be created"); 1782 1783 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1784 { 1785 EXCEPTION_MARK; 1786 1787 CLEAR_PENDING_EXCEPTION; 1788 } 1789 if (!destroy_vm) { 1790 if (uncaught_exception.not_null()) { 1791 EXCEPTION_MARK; 1792 // Call method Thread.dispatchUncaughtException(). 1793 Klass* thread_klass = SystemDictionary::Thread_klass(); 1794 JavaValue result(T_VOID); 1795 JavaCalls::call_virtual(&result, 1796 threadObj, thread_klass, 1797 vmSymbols::dispatchUncaughtException_name(), 1798 vmSymbols::throwable_void_signature(), 1799 uncaught_exception, 1800 THREAD); 1801 if (HAS_PENDING_EXCEPTION) { 1802 ResourceMark rm(this); 1803 jio_fprintf(defaultStream::error_stream(), 1804 "\nException: %s thrown from the UncaughtExceptionHandler" 1805 " in thread \"%s\"\n", 1806 pending_exception()->klass()->external_name(), 1807 get_thread_name()); 1808 CLEAR_PENDING_EXCEPTION; 1809 } 1810 } 1811 1812 // Called before the java thread exit since we want to read info 1813 // from java_lang_Thread object 1814 EventThreadEnd event; 1815 if (event.should_commit()) { 1816 event.set_thread(JFR_THREAD_ID(this)); 1817 event.commit(); 1818 } 1819 1820 // Call after last event on thread 1821 JFR_ONLY(Jfr::on_thread_exit(this);) 1822 1823 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1824 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1825 // is deprecated anyhow. 1826 if (!is_Compiler_thread()) { 1827 int count = 3; 1828 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1829 EXCEPTION_MARK; 1830 JavaValue result(T_VOID); 1831 Klass* thread_klass = SystemDictionary::Thread_klass(); 1832 JavaCalls::call_virtual(&result, 1833 threadObj, thread_klass, 1834 vmSymbols::exit_method_name(), 1835 vmSymbols::void_method_signature(), 1836 THREAD); 1837 CLEAR_PENDING_EXCEPTION; 1838 } 1839 } 1840 // notify JVMTI 1841 if (JvmtiExport::should_post_thread_life()) { 1842 JvmtiExport::post_thread_end(this); 1843 } 1844 1845 // We have notified the agents that we are exiting, before we go on, 1846 // we must check for a pending external suspend request and honor it 1847 // in order to not surprise the thread that made the suspend request. 1848 while (true) { 1849 { 1850 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1851 if (!is_external_suspend()) { 1852 set_terminated(_thread_exiting); 1853 ThreadService::current_thread_exiting(this); 1854 break; 1855 } 1856 // Implied else: 1857 // Things get a little tricky here. We have a pending external 1858 // suspend request, but we are holding the SR_lock so we 1859 // can't just self-suspend. So we temporarily drop the lock 1860 // and then self-suspend. 1861 } 1862 1863 ThreadBlockInVM tbivm(this); 1864 java_suspend_self(); 1865 1866 // We're done with this suspend request, but we have to loop around 1867 // and check again. Eventually we will get SR_lock without a pending 1868 // external suspend request and will be able to mark ourselves as 1869 // exiting. 1870 } 1871 // no more external suspends are allowed at this point 1872 } else { 1873 // before_exit() has already posted JVMTI THREAD_END events 1874 } 1875 1876 if (log_is_enabled(Debug, os, thread, timer)) { 1877 _timer_exit_phase1.stop(); 1878 _timer_exit_phase2.start(); 1879 } 1880 // Notify waiters on thread object. This has to be done after exit() is called 1881 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1882 // group should have the destroyed bit set before waiters are notified). 1883 ensure_join(this); 1884 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1885 1886 if (log_is_enabled(Debug, os, thread, timer)) { 1887 _timer_exit_phase2.stop(); 1888 _timer_exit_phase3.start(); 1889 } 1890 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1891 // held by this thread must be released. The spec does not distinguish 1892 // between JNI-acquired and regular Java monitors. We can only see 1893 // regular Java monitors here if monitor enter-exit matching is broken. 1894 // 1895 // Optionally release any monitors for regular JavaThread exits. This 1896 // is provided as a work around for any bugs in monitor enter-exit 1897 // matching. This can be expensive so it is not enabled by default. 1898 // 1899 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1900 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1901 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1902 // Sanity check even though JNI DetachCurrentThread() would have 1903 // returned JNI_ERR if there was a Java frame. JavaThread exit 1904 // should be done executing Java code by the time we get here. 1905 assert(!this->has_last_Java_frame(), 1906 "should not have a Java frame when detaching or exiting"); 1907 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1908 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1909 } 1910 1911 // These things needs to be done while we are still a Java Thread. Make sure that thread 1912 // is in a consistent state, in case GC happens 1913 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1914 1915 if (active_handles() != NULL) { 1916 JNIHandleBlock* block = active_handles(); 1917 set_active_handles(NULL); 1918 JNIHandleBlock::release_block(block); 1919 } 1920 1921 if (free_handle_block() != NULL) { 1922 JNIHandleBlock* block = free_handle_block(); 1923 set_free_handle_block(NULL); 1924 JNIHandleBlock::release_block(block); 1925 } 1926 1927 // These have to be removed while this is still a valid thread. 1928 remove_stack_guard_pages(); 1929 1930 if (UseTLAB) { 1931 tlab().make_parsable(true); // retire TLAB 1932 } 1933 1934 if (JvmtiEnv::environments_might_exist()) { 1935 JvmtiExport::cleanup_thread(this); 1936 } 1937 1938 // We must flush any deferred card marks and other various GC barrier 1939 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 1940 // before removing a thread from the list of active threads. 1941 BarrierSet::barrier_set()->on_thread_detach(this); 1942 1943 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1944 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1945 os::current_thread_id()); 1946 1947 if (log_is_enabled(Debug, os, thread, timer)) { 1948 _timer_exit_phase3.stop(); 1949 _timer_exit_phase4.start(); 1950 } 1951 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1952 Threads::remove(this); 1953 1954 if (log_is_enabled(Debug, os, thread, timer)) { 1955 _timer_exit_phase4.stop(); 1956 ResourceMark rm(this); 1957 log_debug(os, thread, timer)("name='%s'" 1958 ", exit-phase1=" JLONG_FORMAT 1959 ", exit-phase2=" JLONG_FORMAT 1960 ", exit-phase3=" JLONG_FORMAT 1961 ", exit-phase4=" JLONG_FORMAT, 1962 get_thread_name(), 1963 _timer_exit_phase1.milliseconds(), 1964 _timer_exit_phase2.milliseconds(), 1965 _timer_exit_phase3.milliseconds(), 1966 _timer_exit_phase4.milliseconds()); 1967 } 1968 } 1969 1970 void JavaThread::cleanup_failed_attach_current_thread() { 1971 if (active_handles() != NULL) { 1972 JNIHandleBlock* block = active_handles(); 1973 set_active_handles(NULL); 1974 JNIHandleBlock::release_block(block); 1975 } 1976 1977 if (free_handle_block() != NULL) { 1978 JNIHandleBlock* block = free_handle_block(); 1979 set_free_handle_block(NULL); 1980 JNIHandleBlock::release_block(block); 1981 } 1982 1983 // These have to be removed while this is still a valid thread. 1984 remove_stack_guard_pages(); 1985 1986 if (UseTLAB) { 1987 tlab().make_parsable(true); // retire TLAB, if any 1988 } 1989 1990 BarrierSet::barrier_set()->on_thread_detach(this); 1991 1992 Threads::remove(this); 1993 this->smr_delete(); 1994 } 1995 1996 JavaThread* JavaThread::active() { 1997 Thread* thread = Thread::current(); 1998 if (thread->is_Java_thread()) { 1999 return (JavaThread*) thread; 2000 } else { 2001 assert(thread->is_VM_thread(), "this must be a vm thread"); 2002 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2003 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2004 assert(ret->is_Java_thread(), "must be a Java thread"); 2005 return ret; 2006 } 2007 } 2008 2009 bool JavaThread::is_lock_owned(address adr) const { 2010 if (Thread::is_lock_owned(adr)) return true; 2011 2012 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2013 if (chunk->contains(adr)) return true; 2014 } 2015 2016 return false; 2017 } 2018 2019 2020 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2021 chunk->set_next(monitor_chunks()); 2022 set_monitor_chunks(chunk); 2023 } 2024 2025 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2026 guarantee(monitor_chunks() != NULL, "must be non empty"); 2027 if (monitor_chunks() == chunk) { 2028 set_monitor_chunks(chunk->next()); 2029 } else { 2030 MonitorChunk* prev = monitor_chunks(); 2031 while (prev->next() != chunk) prev = prev->next(); 2032 prev->set_next(chunk->next()); 2033 } 2034 } 2035 2036 // JVM support. 2037 2038 // Note: this function shouldn't block if it's called in 2039 // _thread_in_native_trans state (such as from 2040 // check_special_condition_for_native_trans()). 2041 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2042 2043 if (has_last_Java_frame() && has_async_condition()) { 2044 // If we are at a polling page safepoint (not a poll return) 2045 // then we must defer async exception because live registers 2046 // will be clobbered by the exception path. Poll return is 2047 // ok because the call we a returning from already collides 2048 // with exception handling registers and so there is no issue. 2049 // (The exception handling path kills call result registers but 2050 // this is ok since the exception kills the result anyway). 2051 2052 if (is_at_poll_safepoint()) { 2053 // if the code we are returning to has deoptimized we must defer 2054 // the exception otherwise live registers get clobbered on the 2055 // exception path before deoptimization is able to retrieve them. 2056 // 2057 RegisterMap map(this, false); 2058 frame caller_fr = last_frame().sender(&map); 2059 assert(caller_fr.is_compiled_frame(), "what?"); 2060 if (caller_fr.is_deoptimized_frame()) { 2061 log_info(exceptions)("deferred async exception at compiled safepoint"); 2062 return; 2063 } 2064 } 2065 } 2066 2067 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2068 if (condition == _no_async_condition) { 2069 // Conditions have changed since has_special_runtime_exit_condition() 2070 // was called: 2071 // - if we were here only because of an external suspend request, 2072 // then that was taken care of above (or cancelled) so we are done 2073 // - if we were here because of another async request, then it has 2074 // been cleared between the has_special_runtime_exit_condition() 2075 // and now so again we are done 2076 return; 2077 } 2078 2079 // Check for pending async. exception 2080 if (_pending_async_exception != NULL) { 2081 // Only overwrite an already pending exception, if it is not a threadDeath. 2082 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2083 2084 // We cannot call Exceptions::_throw(...) here because we cannot block 2085 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2086 2087 LogTarget(Info, exceptions) lt; 2088 if (lt.is_enabled()) { 2089 ResourceMark rm; 2090 LogStream ls(lt); 2091 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2092 if (has_last_Java_frame()) { 2093 frame f = last_frame(); 2094 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2095 } 2096 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2097 } 2098 _pending_async_exception = NULL; 2099 clear_has_async_exception(); 2100 } 2101 } 2102 2103 if (check_unsafe_error && 2104 condition == _async_unsafe_access_error && !has_pending_exception()) { 2105 condition = _no_async_condition; // done 2106 switch (thread_state()) { 2107 case _thread_in_vm: { 2108 JavaThread* THREAD = this; 2109 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2110 } 2111 case _thread_in_native: { 2112 ThreadInVMfromNative tiv(this); 2113 JavaThread* THREAD = this; 2114 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2115 } 2116 case _thread_in_Java: { 2117 ThreadInVMfromJava tiv(this); 2118 JavaThread* THREAD = this; 2119 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2120 } 2121 default: 2122 ShouldNotReachHere(); 2123 } 2124 } 2125 2126 assert(condition == _no_async_condition || has_pending_exception() || 2127 (!check_unsafe_error && condition == _async_unsafe_access_error), 2128 "must have handled the async condition, if no exception"); 2129 } 2130 2131 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2132 // 2133 // Check for pending external suspend. Internal suspend requests do 2134 // not use handle_special_runtime_exit_condition(). 2135 // If JNIEnv proxies are allowed, don't self-suspend if the target 2136 // thread is not the current thread. In older versions of jdbx, jdbx 2137 // threads could call into the VM with another thread's JNIEnv so we 2138 // can be here operating on behalf of a suspended thread (4432884). 2139 bool do_self_suspend = is_external_suspend_with_lock(); 2140 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2141 // 2142 // Because thread is external suspended the safepoint code will count 2143 // thread as at a safepoint. This can be odd because we can be here 2144 // as _thread_in_Java which would normally transition to _thread_blocked 2145 // at a safepoint. We would like to mark the thread as _thread_blocked 2146 // before calling java_suspend_self like all other callers of it but 2147 // we must then observe proper safepoint protocol. (We can't leave 2148 // _thread_blocked with a safepoint in progress). However we can be 2149 // here as _thread_in_native_trans so we can't use a normal transition 2150 // constructor/destructor pair because they assert on that type of 2151 // transition. We could do something like: 2152 // 2153 // JavaThreadState state = thread_state(); 2154 // set_thread_state(_thread_in_vm); 2155 // { 2156 // ThreadBlockInVM tbivm(this); 2157 // java_suspend_self() 2158 // } 2159 // set_thread_state(_thread_in_vm_trans); 2160 // if (safepoint) block; 2161 // set_thread_state(state); 2162 // 2163 // but that is pretty messy. Instead we just go with the way the 2164 // code has worked before and note that this is the only path to 2165 // java_suspend_self that doesn't put the thread in _thread_blocked 2166 // mode. 2167 2168 frame_anchor()->make_walkable(this); 2169 java_suspend_self(); 2170 2171 // We might be here for reasons in addition to the self-suspend request 2172 // so check for other async requests. 2173 } 2174 2175 if (check_asyncs) { 2176 check_and_handle_async_exceptions(); 2177 } 2178 2179 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2180 } 2181 2182 void JavaThread::send_thread_stop(oop java_throwable) { 2183 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2184 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2185 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2186 2187 // Do not throw asynchronous exceptions against the compiler thread 2188 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2189 if (!can_call_java()) return; 2190 2191 { 2192 // Actually throw the Throwable against the target Thread - however 2193 // only if there is no thread death exception installed already. 2194 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2195 // If the topmost frame is a runtime stub, then we are calling into 2196 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2197 // must deoptimize the caller before continuing, as the compiled exception handler table 2198 // may not be valid 2199 if (has_last_Java_frame()) { 2200 frame f = last_frame(); 2201 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2202 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2203 RegisterMap reg_map(this, UseBiasedLocking); 2204 frame compiled_frame = f.sender(®_map); 2205 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2206 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2207 } 2208 } 2209 } 2210 2211 // Set async. pending exception in thread. 2212 set_pending_async_exception(java_throwable); 2213 2214 if (log_is_enabled(Info, exceptions)) { 2215 ResourceMark rm; 2216 log_info(exceptions)("Pending Async. exception installed of type: %s", 2217 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2218 } 2219 // for AbortVMOnException flag 2220 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2221 } 2222 } 2223 2224 2225 // Interrupt thread so it will wake up from a potential wait() 2226 Thread::interrupt(this); 2227 } 2228 2229 // External suspension mechanism. 2230 // 2231 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2232 // to any VM_locks and it is at a transition 2233 // Self-suspension will happen on the transition out of the vm. 2234 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2235 // 2236 // Guarantees on return: 2237 // + Target thread will not execute any new bytecode (that's why we need to 2238 // force a safepoint) 2239 // + Target thread will not enter any new monitors 2240 // 2241 void JavaThread::java_suspend() { 2242 ThreadsListHandle tlh; 2243 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2244 return; 2245 } 2246 2247 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2248 if (!is_external_suspend()) { 2249 // a racing resume has cancelled us; bail out now 2250 return; 2251 } 2252 2253 // suspend is done 2254 uint32_t debug_bits = 0; 2255 // Warning: is_ext_suspend_completed() may temporarily drop the 2256 // SR_lock to allow the thread to reach a stable thread state if 2257 // it is currently in a transient thread state. 2258 if (is_ext_suspend_completed(false /* !called_by_wait */, 2259 SuspendRetryDelay, &debug_bits)) { 2260 return; 2261 } 2262 } 2263 2264 VM_ThreadSuspend vm_suspend; 2265 VMThread::execute(&vm_suspend); 2266 } 2267 2268 // Part II of external suspension. 2269 // A JavaThread self suspends when it detects a pending external suspend 2270 // request. This is usually on transitions. It is also done in places 2271 // where continuing to the next transition would surprise the caller, 2272 // e.g., monitor entry. 2273 // 2274 // Returns the number of times that the thread self-suspended. 2275 // 2276 // Note: DO NOT call java_suspend_self() when you just want to block current 2277 // thread. java_suspend_self() is the second stage of cooperative 2278 // suspension for external suspend requests and should only be used 2279 // to complete an external suspend request. 2280 // 2281 int JavaThread::java_suspend_self() { 2282 int ret = 0; 2283 2284 // we are in the process of exiting so don't suspend 2285 if (is_exiting()) { 2286 clear_external_suspend(); 2287 return ret; 2288 } 2289 2290 assert(_anchor.walkable() || 2291 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2292 "must have walkable stack"); 2293 2294 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2295 2296 assert(!this->is_ext_suspended(), 2297 "a thread trying to self-suspend should not already be suspended"); 2298 2299 if (this->is_suspend_equivalent()) { 2300 // If we are self-suspending as a result of the lifting of a 2301 // suspend equivalent condition, then the suspend_equivalent 2302 // flag is not cleared until we set the ext_suspended flag so 2303 // that wait_for_ext_suspend_completion() returns consistent 2304 // results. 2305 this->clear_suspend_equivalent(); 2306 } 2307 2308 // A racing resume may have cancelled us before we grabbed SR_lock 2309 // above. Or another external suspend request could be waiting for us 2310 // by the time we return from SR_lock()->wait(). The thread 2311 // that requested the suspension may already be trying to walk our 2312 // stack and if we return now, we can change the stack out from under 2313 // it. This would be a "bad thing (TM)" and cause the stack walker 2314 // to crash. We stay self-suspended until there are no more pending 2315 // external suspend requests. 2316 while (is_external_suspend()) { 2317 ret++; 2318 this->set_ext_suspended(); 2319 2320 // _ext_suspended flag is cleared by java_resume() 2321 while (is_ext_suspended()) { 2322 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2323 } 2324 } 2325 2326 return ret; 2327 } 2328 2329 #ifdef ASSERT 2330 // Verify the JavaThread has not yet been published in the Threads::list, and 2331 // hence doesn't need protection from concurrent access at this stage. 2332 void JavaThread::verify_not_published() { 2333 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2334 // since an unpublished JavaThread doesn't participate in the 2335 // Thread-SMR protocol for keeping a ThreadsList alive. 2336 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2337 } 2338 #endif 2339 2340 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2341 // progress or when _suspend_flags is non-zero. 2342 // Current thread needs to self-suspend if there is a suspend request and/or 2343 // block if a safepoint is in progress. 2344 // Async exception ISN'T checked. 2345 // Note only the ThreadInVMfromNative transition can call this function 2346 // directly and when thread state is _thread_in_native_trans 2347 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2348 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2349 2350 JavaThread *curJT = JavaThread::current(); 2351 bool do_self_suspend = thread->is_external_suspend(); 2352 2353 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2354 2355 // If JNIEnv proxies are allowed, don't self-suspend if the target 2356 // thread is not the current thread. In older versions of jdbx, jdbx 2357 // threads could call into the VM with another thread's JNIEnv so we 2358 // can be here operating on behalf of a suspended thread (4432884). 2359 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2360 JavaThreadState state = thread->thread_state(); 2361 2362 // We mark this thread_blocked state as a suspend-equivalent so 2363 // that a caller to is_ext_suspend_completed() won't be confused. 2364 // The suspend-equivalent state is cleared by java_suspend_self(). 2365 thread->set_suspend_equivalent(); 2366 2367 // If the safepoint code sees the _thread_in_native_trans state, it will 2368 // wait until the thread changes to other thread state. There is no 2369 // guarantee on how soon we can obtain the SR_lock and complete the 2370 // self-suspend request. It would be a bad idea to let safepoint wait for 2371 // too long. Temporarily change the state to _thread_blocked to 2372 // let the VM thread know that this thread is ready for GC. The problem 2373 // of changing thread state is that safepoint could happen just after 2374 // java_suspend_self() returns after being resumed, and VM thread will 2375 // see the _thread_blocked state. We must check for safepoint 2376 // after restoring the state and make sure we won't leave while a safepoint 2377 // is in progress. 2378 thread->set_thread_state(_thread_blocked); 2379 thread->java_suspend_self(); 2380 thread->set_thread_state(state); 2381 2382 InterfaceSupport::serialize_thread_state_with_handler(thread); 2383 } 2384 2385 SafepointMechanism::block_if_requested(curJT); 2386 2387 if (thread->is_deopt_suspend()) { 2388 thread->clear_deopt_suspend(); 2389 RegisterMap map(thread, false); 2390 frame f = thread->last_frame(); 2391 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2392 f = f.sender(&map); 2393 } 2394 if (f.id() == thread->must_deopt_id()) { 2395 thread->clear_must_deopt_id(); 2396 f.deoptimize(thread); 2397 } else { 2398 fatal("missed deoptimization!"); 2399 } 2400 } 2401 2402 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2403 } 2404 2405 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2406 // progress or when _suspend_flags is non-zero. 2407 // Current thread needs to self-suspend if there is a suspend request and/or 2408 // block if a safepoint is in progress. 2409 // Also check for pending async exception (not including unsafe access error). 2410 // Note only the native==>VM/Java barriers can call this function and when 2411 // thread state is _thread_in_native_trans. 2412 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2413 check_safepoint_and_suspend_for_native_trans(thread); 2414 2415 if (thread->has_async_exception()) { 2416 // We are in _thread_in_native_trans state, don't handle unsafe 2417 // access error since that may block. 2418 thread->check_and_handle_async_exceptions(false); 2419 } 2420 } 2421 2422 // This is a variant of the normal 2423 // check_special_condition_for_native_trans with slightly different 2424 // semantics for use by critical native wrappers. It does all the 2425 // normal checks but also performs the transition back into 2426 // thread_in_Java state. This is required so that critical natives 2427 // can potentially block and perform a GC if they are the last thread 2428 // exiting the GCLocker. 2429 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2430 check_special_condition_for_native_trans(thread); 2431 2432 // Finish the transition 2433 thread->set_thread_state(_thread_in_Java); 2434 2435 if (thread->do_critical_native_unlock()) { 2436 ThreadInVMfromJavaNoAsyncException tiv(thread); 2437 GCLocker::unlock_critical(thread); 2438 thread->clear_critical_native_unlock(); 2439 } 2440 } 2441 2442 // We need to guarantee the Threads_lock here, since resumes are not 2443 // allowed during safepoint synchronization 2444 // Can only resume from an external suspension 2445 void JavaThread::java_resume() { 2446 assert_locked_or_safepoint(Threads_lock); 2447 2448 // Sanity check: thread is gone, has started exiting or the thread 2449 // was not externally suspended. 2450 ThreadsListHandle tlh; 2451 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2452 return; 2453 } 2454 2455 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2456 2457 clear_external_suspend(); 2458 2459 if (is_ext_suspended()) { 2460 clear_ext_suspended(); 2461 SR_lock()->notify_all(); 2462 } 2463 } 2464 2465 size_t JavaThread::_stack_red_zone_size = 0; 2466 size_t JavaThread::_stack_yellow_zone_size = 0; 2467 size_t JavaThread::_stack_reserved_zone_size = 0; 2468 size_t JavaThread::_stack_shadow_zone_size = 0; 2469 2470 void JavaThread::create_stack_guard_pages() { 2471 if (!os::uses_stack_guard_pages() || 2472 _stack_guard_state != stack_guard_unused || 2473 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2474 log_info(os, thread)("Stack guard page creation for thread " 2475 UINTX_FORMAT " disabled", os::current_thread_id()); 2476 return; 2477 } 2478 address low_addr = stack_end(); 2479 size_t len = stack_guard_zone_size(); 2480 2481 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2482 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2483 2484 int must_commit = os::must_commit_stack_guard_pages(); 2485 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2486 2487 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2488 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2489 return; 2490 } 2491 2492 if (os::guard_memory((char *) low_addr, len)) { 2493 _stack_guard_state = stack_guard_enabled; 2494 } else { 2495 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2496 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2497 if (os::uncommit_memory((char *) low_addr, len)) { 2498 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2499 } 2500 return; 2501 } 2502 2503 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2504 PTR_FORMAT "-" PTR_FORMAT ".", 2505 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2506 } 2507 2508 void JavaThread::remove_stack_guard_pages() { 2509 assert(Thread::current() == this, "from different thread"); 2510 if (_stack_guard_state == stack_guard_unused) return; 2511 address low_addr = stack_end(); 2512 size_t len = stack_guard_zone_size(); 2513 2514 if (os::must_commit_stack_guard_pages()) { 2515 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2516 _stack_guard_state = stack_guard_unused; 2517 } else { 2518 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2519 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2520 return; 2521 } 2522 } else { 2523 if (_stack_guard_state == stack_guard_unused) return; 2524 if (os::unguard_memory((char *) low_addr, len)) { 2525 _stack_guard_state = stack_guard_unused; 2526 } else { 2527 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2528 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2529 return; 2530 } 2531 } 2532 2533 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2534 PTR_FORMAT "-" PTR_FORMAT ".", 2535 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2536 } 2537 2538 void JavaThread::enable_stack_reserved_zone() { 2539 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2540 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2541 2542 // The base notation is from the stack's point of view, growing downward. 2543 // We need to adjust it to work correctly with guard_memory() 2544 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2545 2546 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2547 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2548 2549 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2550 _stack_guard_state = stack_guard_enabled; 2551 } else { 2552 warning("Attempt to guard stack reserved zone failed."); 2553 } 2554 enable_register_stack_guard(); 2555 } 2556 2557 void JavaThread::disable_stack_reserved_zone() { 2558 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2559 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2560 2561 // Simply return if called for a thread that does not use guard pages. 2562 if (_stack_guard_state == stack_guard_unused) return; 2563 2564 // The base notation is from the stack's point of view, growing downward. 2565 // We need to adjust it to work correctly with guard_memory() 2566 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2567 2568 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2569 _stack_guard_state = stack_guard_reserved_disabled; 2570 } else { 2571 warning("Attempt to unguard stack reserved zone failed."); 2572 } 2573 disable_register_stack_guard(); 2574 } 2575 2576 void JavaThread::enable_stack_yellow_reserved_zone() { 2577 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2578 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2579 2580 // The base notation is from the stacks point of view, growing downward. 2581 // We need to adjust it to work correctly with guard_memory() 2582 address base = stack_red_zone_base(); 2583 2584 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2585 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2586 2587 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2588 _stack_guard_state = stack_guard_enabled; 2589 } else { 2590 warning("Attempt to guard stack yellow zone failed."); 2591 } 2592 enable_register_stack_guard(); 2593 } 2594 2595 void JavaThread::disable_stack_yellow_reserved_zone() { 2596 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2597 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2598 2599 // Simply return if called for a thread that does not use guard pages. 2600 if (_stack_guard_state == stack_guard_unused) return; 2601 2602 // The base notation is from the stacks point of view, growing downward. 2603 // We need to adjust it to work correctly with guard_memory() 2604 address base = stack_red_zone_base(); 2605 2606 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2607 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2608 } else { 2609 warning("Attempt to unguard stack yellow zone failed."); 2610 } 2611 disable_register_stack_guard(); 2612 } 2613 2614 void JavaThread::enable_stack_red_zone() { 2615 // The base notation is from the stacks point of view, growing downward. 2616 // We need to adjust it to work correctly with guard_memory() 2617 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2618 address base = stack_red_zone_base() - stack_red_zone_size(); 2619 2620 guarantee(base < stack_base(), "Error calculating stack red zone"); 2621 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2622 2623 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2624 warning("Attempt to guard stack red zone failed."); 2625 } 2626 } 2627 2628 void JavaThread::disable_stack_red_zone() { 2629 // The base notation is from the stacks point of view, growing downward. 2630 // We need to adjust it to work correctly with guard_memory() 2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2632 address base = stack_red_zone_base() - stack_red_zone_size(); 2633 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2634 warning("Attempt to unguard stack red zone failed."); 2635 } 2636 } 2637 2638 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2639 // ignore is there is no stack 2640 if (!has_last_Java_frame()) return; 2641 // traverse the stack frames. Starts from top frame. 2642 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2643 frame* fr = fst.current(); 2644 f(fr, fst.register_map()); 2645 } 2646 } 2647 2648 2649 #ifndef PRODUCT 2650 // Deoptimization 2651 // Function for testing deoptimization 2652 void JavaThread::deoptimize() { 2653 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2654 StackFrameStream fst(this, UseBiasedLocking); 2655 bool deopt = false; // Dump stack only if a deopt actually happens. 2656 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2657 // Iterate over all frames in the thread and deoptimize 2658 for (; !fst.is_done(); fst.next()) { 2659 if (fst.current()->can_be_deoptimized()) { 2660 2661 if (only_at) { 2662 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2663 // consists of comma or carriage return separated numbers so 2664 // search for the current bci in that string. 2665 address pc = fst.current()->pc(); 2666 nmethod* nm = (nmethod*) fst.current()->cb(); 2667 ScopeDesc* sd = nm->scope_desc_at(pc); 2668 char buffer[8]; 2669 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2670 size_t len = strlen(buffer); 2671 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2672 while (found != NULL) { 2673 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2674 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2675 // Check that the bci found is bracketed by terminators. 2676 break; 2677 } 2678 found = strstr(found + 1, buffer); 2679 } 2680 if (!found) { 2681 continue; 2682 } 2683 } 2684 2685 if (DebugDeoptimization && !deopt) { 2686 deopt = true; // One-time only print before deopt 2687 tty->print_cr("[BEFORE Deoptimization]"); 2688 trace_frames(); 2689 trace_stack(); 2690 } 2691 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2692 } 2693 } 2694 2695 if (DebugDeoptimization && deopt) { 2696 tty->print_cr("[AFTER Deoptimization]"); 2697 trace_frames(); 2698 } 2699 } 2700 2701 2702 // Make zombies 2703 void JavaThread::make_zombies() { 2704 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2705 if (fst.current()->can_be_deoptimized()) { 2706 // it is a Java nmethod 2707 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2708 nm->make_not_entrant(); 2709 } 2710 } 2711 } 2712 #endif // PRODUCT 2713 2714 2715 void JavaThread::deoptimized_wrt_marked_nmethods() { 2716 if (!has_last_Java_frame()) return; 2717 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2718 StackFrameStream fst(this, UseBiasedLocking); 2719 for (; !fst.is_done(); fst.next()) { 2720 if (fst.current()->should_be_deoptimized()) { 2721 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2722 } 2723 } 2724 } 2725 2726 2727 // If the caller is a NamedThread, then remember, in the current scope, 2728 // the given JavaThread in its _processed_thread field. 2729 class RememberProcessedThread: public StackObj { 2730 NamedThread* _cur_thr; 2731 public: 2732 RememberProcessedThread(JavaThread* jthr) { 2733 Thread* thread = Thread::current(); 2734 if (thread->is_Named_thread()) { 2735 _cur_thr = (NamedThread *)thread; 2736 _cur_thr->set_processed_thread(jthr); 2737 } else { 2738 _cur_thr = NULL; 2739 } 2740 } 2741 2742 ~RememberProcessedThread() { 2743 if (_cur_thr) { 2744 _cur_thr->set_processed_thread(NULL); 2745 } 2746 } 2747 }; 2748 2749 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2750 // Verify that the deferred card marks have been flushed. 2751 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2752 2753 // Traverse the GCHandles 2754 Thread::oops_do(f, cf); 2755 2756 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2757 2758 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2759 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2760 2761 if (has_last_Java_frame()) { 2762 // Record JavaThread to GC thread 2763 RememberProcessedThread rpt(this); 2764 2765 // Traverse the privileged stack 2766 if (_privileged_stack_top != NULL) { 2767 _privileged_stack_top->oops_do(f); 2768 } 2769 2770 // traverse the registered growable array 2771 if (_array_for_gc != NULL) { 2772 for (int index = 0; index < _array_for_gc->length(); index++) { 2773 f->do_oop(_array_for_gc->adr_at(index)); 2774 } 2775 } 2776 2777 // Traverse the monitor chunks 2778 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2779 chunk->oops_do(f); 2780 } 2781 2782 // Traverse the execution stack 2783 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2784 fst.current()->oops_do(f, cf, fst.register_map()); 2785 } 2786 } 2787 2788 // callee_target is never live across a gc point so NULL it here should 2789 // it still contain a methdOop. 2790 2791 set_callee_target(NULL); 2792 2793 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2794 // If we have deferred set_locals there might be oops waiting to be 2795 // written 2796 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2797 if (list != NULL) { 2798 for (int i = 0; i < list->length(); i++) { 2799 list->at(i)->oops_do(f); 2800 } 2801 } 2802 2803 // Traverse instance variables at the end since the GC may be moving things 2804 // around using this function 2805 f->do_oop((oop*) &_threadObj); 2806 f->do_oop((oop*) &_vm_result); 2807 f->do_oop((oop*) &_exception_oop); 2808 f->do_oop((oop*) &_pending_async_exception); 2809 2810 if (jvmti_thread_state() != NULL) { 2811 jvmti_thread_state()->oops_do(f); 2812 } 2813 } 2814 2815 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2816 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2817 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2818 2819 if (has_last_Java_frame()) { 2820 // Traverse the execution stack 2821 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2822 fst.current()->nmethods_do(cf); 2823 } 2824 } 2825 } 2826 2827 void JavaThread::metadata_do(void f(Metadata*)) { 2828 if (has_last_Java_frame()) { 2829 // Traverse the execution stack to call f() on the methods in the stack 2830 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2831 fst.current()->metadata_do(f); 2832 } 2833 } else if (is_Compiler_thread()) { 2834 // need to walk ciMetadata in current compile tasks to keep alive. 2835 CompilerThread* ct = (CompilerThread*)this; 2836 if (ct->env() != NULL) { 2837 ct->env()->metadata_do(f); 2838 } 2839 CompileTask* task = ct->task(); 2840 if (task != NULL) { 2841 task->metadata_do(f); 2842 } 2843 } 2844 } 2845 2846 // Printing 2847 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2848 switch (_thread_state) { 2849 case _thread_uninitialized: return "_thread_uninitialized"; 2850 case _thread_new: return "_thread_new"; 2851 case _thread_new_trans: return "_thread_new_trans"; 2852 case _thread_in_native: return "_thread_in_native"; 2853 case _thread_in_native_trans: return "_thread_in_native_trans"; 2854 case _thread_in_vm: return "_thread_in_vm"; 2855 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2856 case _thread_in_Java: return "_thread_in_Java"; 2857 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2858 case _thread_blocked: return "_thread_blocked"; 2859 case _thread_blocked_trans: return "_thread_blocked_trans"; 2860 default: return "unknown thread state"; 2861 } 2862 } 2863 2864 #ifndef PRODUCT 2865 void JavaThread::print_thread_state_on(outputStream *st) const { 2866 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2867 }; 2868 void JavaThread::print_thread_state() const { 2869 print_thread_state_on(tty); 2870 } 2871 #endif // PRODUCT 2872 2873 // Called by Threads::print() for VM_PrintThreads operation 2874 void JavaThread::print_on(outputStream *st) const { 2875 st->print_raw("\""); 2876 st->print_raw(get_thread_name()); 2877 st->print_raw("\" "); 2878 oop thread_oop = threadObj(); 2879 if (thread_oop != NULL) { 2880 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2881 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2882 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2883 } 2884 Thread::print_on(st); 2885 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2886 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2887 if (thread_oop != NULL) { 2888 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2889 } 2890 #ifndef PRODUCT 2891 print_thread_state_on(st); 2892 _safepoint_state->print_on(st); 2893 #endif // PRODUCT 2894 if (is_Compiler_thread()) { 2895 CompileTask *task = ((CompilerThread*)this)->task(); 2896 if (task != NULL) { 2897 st->print(" Compiling: "); 2898 task->print(st, NULL, true, false); 2899 } else { 2900 st->print(" No compile task"); 2901 } 2902 st->cr(); 2903 } 2904 } 2905 2906 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2907 st->print("%s", get_thread_name_string(buf, buflen)); 2908 } 2909 2910 // Called by fatal error handler. The difference between this and 2911 // JavaThread::print() is that we can't grab lock or allocate memory. 2912 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2913 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2914 oop thread_obj = threadObj(); 2915 if (thread_obj != NULL) { 2916 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2917 } 2918 st->print(" ["); 2919 st->print("%s", _get_thread_state_name(_thread_state)); 2920 if (osthread()) { 2921 st->print(", id=%d", osthread()->thread_id()); 2922 } 2923 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2924 p2i(stack_end()), p2i(stack_base())); 2925 st->print("]"); 2926 2927 ThreadsSMRSupport::print_info_on(this, st); 2928 return; 2929 } 2930 2931 // Verification 2932 2933 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2934 2935 void JavaThread::verify() { 2936 // Verify oops in the thread. 2937 oops_do(&VerifyOopClosure::verify_oop, NULL); 2938 2939 // Verify the stack frames. 2940 frames_do(frame_verify); 2941 } 2942 2943 // CR 6300358 (sub-CR 2137150) 2944 // Most callers of this method assume that it can't return NULL but a 2945 // thread may not have a name whilst it is in the process of attaching to 2946 // the VM - see CR 6412693, and there are places where a JavaThread can be 2947 // seen prior to having it's threadObj set (eg JNI attaching threads and 2948 // if vm exit occurs during initialization). These cases can all be accounted 2949 // for such that this method never returns NULL. 2950 const char* JavaThread::get_thread_name() const { 2951 #ifdef ASSERT 2952 // early safepoints can hit while current thread does not yet have TLS 2953 if (!SafepointSynchronize::is_at_safepoint()) { 2954 Thread *cur = Thread::current(); 2955 if (!(cur->is_Java_thread() && cur == this)) { 2956 // Current JavaThreads are allowed to get their own name without 2957 // the Threads_lock. 2958 assert_locked_or_safepoint(Threads_lock); 2959 } 2960 } 2961 #endif // ASSERT 2962 return get_thread_name_string(); 2963 } 2964 2965 // Returns a non-NULL representation of this thread's name, or a suitable 2966 // descriptive string if there is no set name 2967 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2968 const char* name_str; 2969 oop thread_obj = threadObj(); 2970 if (thread_obj != NULL) { 2971 oop name = java_lang_Thread::name(thread_obj); 2972 if (name != NULL) { 2973 if (buf == NULL) { 2974 name_str = java_lang_String::as_utf8_string(name); 2975 } else { 2976 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2977 } 2978 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2979 name_str = "<no-name - thread is attaching>"; 2980 } else { 2981 name_str = Thread::name(); 2982 } 2983 } else { 2984 name_str = Thread::name(); 2985 } 2986 assert(name_str != NULL, "unexpected NULL thread name"); 2987 return name_str; 2988 } 2989 2990 2991 const char* JavaThread::get_threadgroup_name() const { 2992 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2993 oop thread_obj = threadObj(); 2994 if (thread_obj != NULL) { 2995 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2996 if (thread_group != NULL) { 2997 // ThreadGroup.name can be null 2998 return java_lang_ThreadGroup::name(thread_group); 2999 } 3000 } 3001 return NULL; 3002 } 3003 3004 const char* JavaThread::get_parent_name() const { 3005 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3006 oop thread_obj = threadObj(); 3007 if (thread_obj != NULL) { 3008 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3009 if (thread_group != NULL) { 3010 oop parent = java_lang_ThreadGroup::parent(thread_group); 3011 if (parent != NULL) { 3012 // ThreadGroup.name can be null 3013 return java_lang_ThreadGroup::name(parent); 3014 } 3015 } 3016 } 3017 return NULL; 3018 } 3019 3020 ThreadPriority JavaThread::java_priority() const { 3021 oop thr_oop = threadObj(); 3022 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3023 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3024 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3025 return priority; 3026 } 3027 3028 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3029 3030 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3031 // Link Java Thread object <-> C++ Thread 3032 3033 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3034 // and put it into a new Handle. The Handle "thread_oop" can then 3035 // be used to pass the C++ thread object to other methods. 3036 3037 // Set the Java level thread object (jthread) field of the 3038 // new thread (a JavaThread *) to C++ thread object using the 3039 // "thread_oop" handle. 3040 3041 // Set the thread field (a JavaThread *) of the 3042 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3043 3044 Handle thread_oop(Thread::current(), 3045 JNIHandles::resolve_non_null(jni_thread)); 3046 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3047 "must be initialized"); 3048 set_threadObj(thread_oop()); 3049 java_lang_Thread::set_thread(thread_oop(), this); 3050 3051 if (prio == NoPriority) { 3052 prio = java_lang_Thread::priority(thread_oop()); 3053 assert(prio != NoPriority, "A valid priority should be present"); 3054 } 3055 3056 // Push the Java priority down to the native thread; needs Threads_lock 3057 Thread::set_priority(this, prio); 3058 3059 // Add the new thread to the Threads list and set it in motion. 3060 // We must have threads lock in order to call Threads::add. 3061 // It is crucial that we do not block before the thread is 3062 // added to the Threads list for if a GC happens, then the java_thread oop 3063 // will not be visited by GC. 3064 Threads::add(this); 3065 } 3066 3067 oop JavaThread::current_park_blocker() { 3068 // Support for JSR-166 locks 3069 oop thread_oop = threadObj(); 3070 if (thread_oop != NULL && 3071 JDK_Version::current().supports_thread_park_blocker()) { 3072 return java_lang_Thread::park_blocker(thread_oop); 3073 } 3074 return NULL; 3075 } 3076 3077 3078 void JavaThread::print_stack_on(outputStream* st) { 3079 if (!has_last_Java_frame()) return; 3080 ResourceMark rm; 3081 HandleMark hm; 3082 3083 RegisterMap reg_map(this); 3084 vframe* start_vf = last_java_vframe(®_map); 3085 int count = 0; 3086 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3087 if (f->is_java_frame()) { 3088 javaVFrame* jvf = javaVFrame::cast(f); 3089 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3090 3091 // Print out lock information 3092 if (JavaMonitorsInStackTrace) { 3093 jvf->print_lock_info_on(st, count); 3094 } 3095 } else { 3096 // Ignore non-Java frames 3097 } 3098 3099 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3100 count++; 3101 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3102 } 3103 } 3104 3105 3106 // JVMTI PopFrame support 3107 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3108 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3109 if (in_bytes(size_in_bytes) != 0) { 3110 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3111 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3112 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3113 } 3114 } 3115 3116 void* JavaThread::popframe_preserved_args() { 3117 return _popframe_preserved_args; 3118 } 3119 3120 ByteSize JavaThread::popframe_preserved_args_size() { 3121 return in_ByteSize(_popframe_preserved_args_size); 3122 } 3123 3124 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3125 int sz = in_bytes(popframe_preserved_args_size()); 3126 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3127 return in_WordSize(sz / wordSize); 3128 } 3129 3130 void JavaThread::popframe_free_preserved_args() { 3131 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3132 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3133 _popframe_preserved_args = NULL; 3134 _popframe_preserved_args_size = 0; 3135 } 3136 3137 #ifndef PRODUCT 3138 3139 void JavaThread::trace_frames() { 3140 tty->print_cr("[Describe stack]"); 3141 int frame_no = 1; 3142 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3143 tty->print(" %d. ", frame_no++); 3144 fst.current()->print_value_on(tty, this); 3145 tty->cr(); 3146 } 3147 } 3148 3149 class PrintAndVerifyOopClosure: public OopClosure { 3150 protected: 3151 template <class T> inline void do_oop_work(T* p) { 3152 oop obj = RawAccess<>::oop_load(p); 3153 if (obj == NULL) return; 3154 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3155 if (oopDesc::is_oop_or_null(obj)) { 3156 if (obj->is_objArray()) { 3157 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3158 } else { 3159 obj->print(); 3160 } 3161 } else { 3162 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3163 } 3164 tty->cr(); 3165 } 3166 public: 3167 virtual void do_oop(oop* p) { do_oop_work(p); } 3168 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3169 }; 3170 3171 3172 static void oops_print(frame* f, const RegisterMap *map) { 3173 PrintAndVerifyOopClosure print; 3174 f->print_value(); 3175 f->oops_do(&print, NULL, (RegisterMap*)map); 3176 } 3177 3178 // Print our all the locations that contain oops and whether they are 3179 // valid or not. This useful when trying to find the oldest frame 3180 // where an oop has gone bad since the frame walk is from youngest to 3181 // oldest. 3182 void JavaThread::trace_oops() { 3183 tty->print_cr("[Trace oops]"); 3184 frames_do(oops_print); 3185 } 3186 3187 3188 #ifdef ASSERT 3189 // Print or validate the layout of stack frames 3190 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3191 ResourceMark rm; 3192 PRESERVE_EXCEPTION_MARK; 3193 FrameValues values; 3194 int frame_no = 0; 3195 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3196 fst.current()->describe(values, ++frame_no); 3197 if (depth == frame_no) break; 3198 } 3199 if (validate_only) { 3200 values.validate(); 3201 } else { 3202 tty->print_cr("[Describe stack layout]"); 3203 values.print(this); 3204 } 3205 } 3206 #endif 3207 3208 void JavaThread::trace_stack_from(vframe* start_vf) { 3209 ResourceMark rm; 3210 int vframe_no = 1; 3211 for (vframe* f = start_vf; f; f = f->sender()) { 3212 if (f->is_java_frame()) { 3213 javaVFrame::cast(f)->print_activation(vframe_no++); 3214 } else { 3215 f->print(); 3216 } 3217 if (vframe_no > StackPrintLimit) { 3218 tty->print_cr("...<more frames>..."); 3219 return; 3220 } 3221 } 3222 } 3223 3224 3225 void JavaThread::trace_stack() { 3226 if (!has_last_Java_frame()) return; 3227 ResourceMark rm; 3228 HandleMark hm; 3229 RegisterMap reg_map(this); 3230 trace_stack_from(last_java_vframe(®_map)); 3231 } 3232 3233 3234 #endif // PRODUCT 3235 3236 3237 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3238 assert(reg_map != NULL, "a map must be given"); 3239 frame f = last_frame(); 3240 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3241 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3242 } 3243 return NULL; 3244 } 3245 3246 3247 Klass* JavaThread::security_get_caller_class(int depth) { 3248 vframeStream vfst(this); 3249 vfst.security_get_caller_frame(depth); 3250 if (!vfst.at_end()) { 3251 return vfst.method()->method_holder(); 3252 } 3253 return NULL; 3254 } 3255 3256 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3257 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3258 CompileBroker::compiler_thread_loop(); 3259 } 3260 3261 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3262 NMethodSweeper::sweeper_loop(); 3263 } 3264 3265 // Create a CompilerThread 3266 CompilerThread::CompilerThread(CompileQueue* queue, 3267 CompilerCounters* counters) 3268 : JavaThread(&compiler_thread_entry) { 3269 _env = NULL; 3270 _log = NULL; 3271 _task = NULL; 3272 _queue = queue; 3273 _counters = counters; 3274 _buffer_blob = NULL; 3275 _compiler = NULL; 3276 3277 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3278 resource_area()->bias_to(mtCompiler); 3279 3280 #ifndef PRODUCT 3281 _ideal_graph_printer = NULL; 3282 #endif 3283 } 3284 3285 CompilerThread::~CompilerThread() { 3286 // Delete objects which were allocated on heap. 3287 delete _counters; 3288 } 3289 3290 bool CompilerThread::can_call_java() const { 3291 return _compiler != NULL && _compiler->is_jvmci(); 3292 } 3293 3294 // Create sweeper thread 3295 CodeCacheSweeperThread::CodeCacheSweeperThread() 3296 : JavaThread(&sweeper_thread_entry) { 3297 _scanned_compiled_method = NULL; 3298 } 3299 3300 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3301 JavaThread::oops_do(f, cf); 3302 if (_scanned_compiled_method != NULL && cf != NULL) { 3303 // Safepoints can occur when the sweeper is scanning an nmethod so 3304 // process it here to make sure it isn't unloaded in the middle of 3305 // a scan. 3306 cf->do_code_blob(_scanned_compiled_method); 3307 } 3308 } 3309 3310 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3311 JavaThread::nmethods_do(cf); 3312 if (_scanned_compiled_method != NULL && cf != NULL) { 3313 // Safepoints can occur when the sweeper is scanning an nmethod so 3314 // process it here to make sure it isn't unloaded in the middle of 3315 // a scan. 3316 cf->do_code_blob(_scanned_compiled_method); 3317 } 3318 } 3319 3320 3321 // ======= Threads ======== 3322 3323 // The Threads class links together all active threads, and provides 3324 // operations over all threads. It is protected by the Threads_lock, 3325 // which is also used in other global contexts like safepointing. 3326 // ThreadsListHandles are used to safely perform operations on one 3327 // or more threads without the risk of the thread exiting during the 3328 // operation. 3329 // 3330 // Note: The Threads_lock is currently more widely used than we 3331 // would like. We are actively migrating Threads_lock uses to other 3332 // mechanisms in order to reduce Threads_lock contention. 3333 3334 JavaThread* Threads::_thread_list = NULL; 3335 int Threads::_number_of_threads = 0; 3336 int Threads::_number_of_non_daemon_threads = 0; 3337 int Threads::_return_code = 0; 3338 int Threads::_thread_claim_parity = 0; 3339 size_t JavaThread::_stack_size_at_create = 0; 3340 3341 #ifdef ASSERT 3342 bool Threads::_vm_complete = false; 3343 #endif 3344 3345 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3346 Prefetch::read((void*)addr, prefetch_interval); 3347 return *addr; 3348 } 3349 3350 // Possibly the ugliest for loop the world has seen. C++ does not allow 3351 // multiple types in the declaration section of the for loop. In this case 3352 // we are only dealing with pointers and hence can cast them. It looks ugly 3353 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3354 #define DO_JAVA_THREADS(LIST, X) \ 3355 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3356 *MACRO_list = (JavaThread*)(LIST), \ 3357 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3358 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3359 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3360 MACRO_current_p != MACRO_end; \ 3361 MACRO_current_p++, \ 3362 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3363 3364 // All JavaThreads 3365 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3366 3367 // All non-JavaThreads (i.e., every non-JavaThread in the system). 3368 void Threads::non_java_threads_do(ThreadClosure* tc) { 3369 // Someday we could have a table or list of all non-JavaThreads. 3370 // For now, just manually iterate through them. 3371 tc->do_thread(VMThread::vm_thread()); 3372 if (Universe::heap() != NULL) { 3373 Universe::heap()->gc_threads_do(tc); 3374 } 3375 WatcherThread *wt = WatcherThread::watcher_thread(); 3376 // Strictly speaking, the following NULL check isn't sufficient to make sure 3377 // the data for WatcherThread is still valid upon being examined. However, 3378 // considering that WatchThread terminates when the VM is on the way to 3379 // exit at safepoint, the chance of the above is extremely small. The right 3380 // way to prevent termination of WatcherThread would be to acquire 3381 // Terminator_lock, but we can't do that without violating the lock rank 3382 // checking in some cases. 3383 if (wt != NULL) { 3384 tc->do_thread(wt); 3385 } 3386 3387 #if INCLUDE_JFR 3388 Thread* sampler_thread = Jfr::sampler_thread(); 3389 if (sampler_thread != NULL) { 3390 tc->do_thread(sampler_thread); 3391 } 3392 3393 #endif 3394 3395 // If CompilerThreads ever become non-JavaThreads, add them here 3396 } 3397 3398 // All JavaThreads 3399 void Threads::java_threads_do(ThreadClosure* tc) { 3400 assert_locked_or_safepoint(Threads_lock); 3401 // ALL_JAVA_THREADS iterates through all JavaThreads. 3402 ALL_JAVA_THREADS(p) { 3403 tc->do_thread(p); 3404 } 3405 } 3406 3407 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3408 assert_locked_or_safepoint(Threads_lock); 3409 java_threads_do(tc); 3410 tc->do_thread(VMThread::vm_thread()); 3411 } 3412 3413 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3414 void Threads::threads_do(ThreadClosure* tc) { 3415 assert_locked_or_safepoint(Threads_lock); 3416 java_threads_do(tc); 3417 non_java_threads_do(tc); 3418 } 3419 3420 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3421 int cp = Threads::thread_claim_parity(); 3422 ALL_JAVA_THREADS(p) { 3423 if (p->claim_oops_do(is_par, cp)) { 3424 tc->do_thread(p); 3425 } 3426 } 3427 VMThread* vmt = VMThread::vm_thread(); 3428 if (vmt->claim_oops_do(is_par, cp)) { 3429 tc->do_thread(vmt); 3430 } 3431 } 3432 3433 // The system initialization in the library has three phases. 3434 // 3435 // Phase 1: java.lang.System class initialization 3436 // java.lang.System is a primordial class loaded and initialized 3437 // by the VM early during startup. java.lang.System.<clinit> 3438 // only does registerNatives and keeps the rest of the class 3439 // initialization work later until thread initialization completes. 3440 // 3441 // System.initPhase1 initializes the system properties, the static 3442 // fields in, out, and err. Set up java signal handlers, OS-specific 3443 // system settings, and thread group of the main thread. 3444 static void call_initPhase1(TRAPS) { 3445 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3446 JavaValue result(T_VOID); 3447 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3448 vmSymbols::void_method_signature(), CHECK); 3449 } 3450 3451 // Phase 2. Module system initialization 3452 // This will initialize the module system. Only java.base classes 3453 // can be loaded until phase 2 completes. 3454 // 3455 // Call System.initPhase2 after the compiler initialization and jsr292 3456 // classes get initialized because module initialization runs a lot of java 3457 // code, that for performance reasons, should be compiled. Also, this will 3458 // enable the startup code to use lambda and other language features in this 3459 // phase and onward. 3460 // 3461 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3462 static void call_initPhase2(TRAPS) { 3463 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3464 3465 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3466 3467 JavaValue result(T_INT); 3468 JavaCallArguments args; 3469 args.push_int(DisplayVMOutputToStderr); 3470 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3471 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3472 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3473 if (result.get_jint() != JNI_OK) { 3474 vm_exit_during_initialization(); // no message or exception 3475 } 3476 3477 universe_post_module_init(); 3478 } 3479 3480 // Phase 3. final setup - set security manager, system class loader and TCCL 3481 // 3482 // This will instantiate and set the security manager, set the system class 3483 // loader as well as the thread context class loader. The security manager 3484 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3485 // other modules or the application's classpath. 3486 static void call_initPhase3(TRAPS) { 3487 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3488 JavaValue result(T_VOID); 3489 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3490 vmSymbols::void_method_signature(), CHECK); 3491 } 3492 3493 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3494 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3495 3496 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3497 create_vm_init_libraries(); 3498 } 3499 3500 initialize_class(vmSymbols::java_lang_String(), CHECK); 3501 3502 // Inject CompactStrings value after the static initializers for String ran. 3503 java_lang_String::set_compact_strings(CompactStrings); 3504 3505 // Initialize java_lang.System (needed before creating the thread) 3506 initialize_class(vmSymbols::java_lang_System(), CHECK); 3507 // The VM creates & returns objects of this class. Make sure it's initialized. 3508 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3509 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3510 Handle thread_group = create_initial_thread_group(CHECK); 3511 Universe::set_main_thread_group(thread_group()); 3512 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3513 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3514 main_thread->set_threadObj(thread_object); 3515 // Set thread status to running since main thread has 3516 // been started and running. 3517 java_lang_Thread::set_thread_status(thread_object, 3518 java_lang_Thread::RUNNABLE); 3519 3520 // The VM creates objects of this class. 3521 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3522 3523 // The VM preresolves methods to these classes. Make sure that they get initialized 3524 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3525 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3526 3527 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3528 call_initPhase1(CHECK); 3529 3530 // get the Java runtime name after java.lang.System is initialized 3531 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3532 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3533 3534 // an instance of OutOfMemory exception has been allocated earlier 3535 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3536 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3537 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3538 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3539 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3540 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3541 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3542 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3543 } 3544 3545 void Threads::initialize_jsr292_core_classes(TRAPS) { 3546 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3547 3548 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3549 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3550 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3551 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3552 } 3553 3554 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3555 extern void JDK_Version_init(); 3556 3557 // Preinitialize version info. 3558 VM_Version::early_initialize(); 3559 3560 // Check version 3561 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3562 3563 // Initialize library-based TLS 3564 ThreadLocalStorage::init(); 3565 3566 // Initialize the output stream module 3567 ostream_init(); 3568 3569 // Process java launcher properties. 3570 Arguments::process_sun_java_launcher_properties(args); 3571 3572 // Initialize the os module 3573 os::init(); 3574 3575 // Record VM creation timing statistics 3576 TraceVmCreationTime create_vm_timer; 3577 create_vm_timer.start(); 3578 3579 // Initialize system properties. 3580 Arguments::init_system_properties(); 3581 3582 // So that JDK version can be used as a discriminator when parsing arguments 3583 JDK_Version_init(); 3584 3585 // Update/Initialize System properties after JDK version number is known 3586 Arguments::init_version_specific_system_properties(); 3587 3588 // Make sure to initialize log configuration *before* parsing arguments 3589 LogConfiguration::initialize(create_vm_timer.begin_time()); 3590 3591 // Parse arguments 3592 // Note: this internally calls os::init_container_support() 3593 jint parse_result = Arguments::parse(args); 3594 if (parse_result != JNI_OK) return parse_result; 3595 3596 os::init_before_ergo(); 3597 3598 jint ergo_result = Arguments::apply_ergo(); 3599 if (ergo_result != JNI_OK) return ergo_result; 3600 3601 // Final check of all ranges after ergonomics which may change values. 3602 if (!JVMFlagRangeList::check_ranges()) { 3603 return JNI_EINVAL; 3604 } 3605 3606 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3607 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3608 if (!constraint_result) { 3609 return JNI_EINVAL; 3610 } 3611 3612 JVMFlagWriteableList::mark_startup(); 3613 3614 if (PauseAtStartup) { 3615 os::pause(); 3616 } 3617 3618 HOTSPOT_VM_INIT_BEGIN(); 3619 3620 // Timing (must come after argument parsing) 3621 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3622 3623 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3624 // Initialize assert poison page mechanism. 3625 if (ShowRegistersOnAssert) { 3626 initialize_assert_poison(); 3627 } 3628 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3629 3630 // Initialize the os module after parsing the args 3631 jint os_init_2_result = os::init_2(); 3632 if (os_init_2_result != JNI_OK) return os_init_2_result; 3633 3634 SafepointMechanism::initialize(); 3635 3636 jint adjust_after_os_result = Arguments::adjust_after_os(); 3637 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3638 3639 // Initialize output stream logging 3640 ostream_init_log(); 3641 3642 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3643 // Must be before create_vm_init_agents() 3644 if (Arguments::init_libraries_at_startup()) { 3645 convert_vm_init_libraries_to_agents(); 3646 } 3647 3648 // Launch -agentlib/-agentpath and converted -Xrun agents 3649 if (Arguments::init_agents_at_startup()) { 3650 create_vm_init_agents(); 3651 } 3652 3653 // Initialize Threads state 3654 _thread_list = NULL; 3655 _number_of_threads = 0; 3656 _number_of_non_daemon_threads = 0; 3657 3658 // Initialize global data structures and create system classes in heap 3659 vm_init_globals(); 3660 3661 #if INCLUDE_JVMCI 3662 if (JVMCICounterSize > 0) { 3663 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3664 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3665 } else { 3666 JavaThread::_jvmci_old_thread_counters = NULL; 3667 } 3668 #endif // INCLUDE_JVMCI 3669 3670 // Attach the main thread to this os thread 3671 JavaThread* main_thread = new JavaThread(); 3672 main_thread->set_thread_state(_thread_in_vm); 3673 main_thread->initialize_thread_current(); 3674 // must do this before set_active_handles 3675 main_thread->record_stack_base_and_size(); 3676 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3677 3678 if (!main_thread->set_as_starting_thread()) { 3679 vm_shutdown_during_initialization( 3680 "Failed necessary internal allocation. Out of swap space"); 3681 main_thread->smr_delete(); 3682 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3683 return JNI_ENOMEM; 3684 } 3685 3686 // Enable guard page *after* os::create_main_thread(), otherwise it would 3687 // crash Linux VM, see notes in os_linux.cpp. 3688 main_thread->create_stack_guard_pages(); 3689 3690 // Initialize Java-Level synchronization subsystem 3691 ObjectMonitor::Initialize(); 3692 3693 // Initialize global modules 3694 jint status = init_globals(); 3695 if (status != JNI_OK) { 3696 main_thread->smr_delete(); 3697 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3698 return status; 3699 } 3700 3701 JFR_ONLY(Jfr::on_vm_init();) 3702 3703 // Should be done after the heap is fully created 3704 main_thread->cache_global_variables(); 3705 3706 HandleMark hm; 3707 3708 { MutexLocker mu(Threads_lock); 3709 Threads::add(main_thread); 3710 } 3711 3712 // Any JVMTI raw monitors entered in onload will transition into 3713 // real raw monitor. VM is setup enough here for raw monitor enter. 3714 JvmtiExport::transition_pending_onload_raw_monitors(); 3715 3716 // Create the VMThread 3717 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3718 3719 VMThread::create(); 3720 Thread* vmthread = VMThread::vm_thread(); 3721 3722 if (!os::create_thread(vmthread, os::vm_thread)) { 3723 vm_exit_during_initialization("Cannot create VM thread. " 3724 "Out of system resources."); 3725 } 3726 3727 // Wait for the VM thread to become ready, and VMThread::run to initialize 3728 // Monitors can have spurious returns, must always check another state flag 3729 { 3730 MutexLocker ml(Notify_lock); 3731 os::start_thread(vmthread); 3732 while (vmthread->active_handles() == NULL) { 3733 Notify_lock->wait(); 3734 } 3735 } 3736 } 3737 3738 assert(Universe::is_fully_initialized(), "not initialized"); 3739 if (VerifyDuringStartup) { 3740 // Make sure we're starting with a clean slate. 3741 VM_Verify verify_op; 3742 VMThread::execute(&verify_op); 3743 } 3744 3745 // We need this to update the java.vm.info property in case any flags used 3746 // to initially define it have been changed. This is needed for both CDS and 3747 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3748 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3749 // This update must happen before we initialize the java classes, but 3750 // after any initialization logic that might modify the flags. 3751 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3752 3753 Thread* THREAD = Thread::current(); 3754 3755 // Always call even when there are not JVMTI environments yet, since environments 3756 // may be attached late and JVMTI must track phases of VM execution 3757 JvmtiExport::enter_early_start_phase(); 3758 3759 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3760 JvmtiExport::post_early_vm_start(); 3761 3762 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3763 3764 quicken_jni_functions(); 3765 3766 // No more stub generation allowed after that point. 3767 StubCodeDesc::freeze(); 3768 3769 // Set flag that basic initialization has completed. Used by exceptions and various 3770 // debug stuff, that does not work until all basic classes have been initialized. 3771 set_init_completed(); 3772 3773 LogConfiguration::post_initialize(); 3774 Metaspace::post_initialize(); 3775 3776 HOTSPOT_VM_INIT_END(); 3777 3778 // record VM initialization completion time 3779 #if INCLUDE_MANAGEMENT 3780 Management::record_vm_init_completed(); 3781 #endif // INCLUDE_MANAGEMENT 3782 3783 // Signal Dispatcher needs to be started before VMInit event is posted 3784 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3785 3786 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3787 if (!DisableAttachMechanism) { 3788 AttachListener::vm_start(); 3789 if (StartAttachListener || AttachListener::init_at_startup()) { 3790 AttachListener::init(); 3791 } 3792 } 3793 3794 // Launch -Xrun agents 3795 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3796 // back-end can launch with -Xdebug -Xrunjdwp. 3797 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3798 create_vm_init_libraries(); 3799 } 3800 3801 if (CleanChunkPoolAsync) { 3802 Chunk::start_chunk_pool_cleaner_task(); 3803 } 3804 3805 // initialize compiler(s) 3806 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3807 #if INCLUDE_JVMCI 3808 bool force_JVMCI_intialization = false; 3809 if (EnableJVMCI) { 3810 // Initialize JVMCI eagerly when it is explicitly requested. 3811 // Or when JVMCIPrintProperties is enabled. 3812 // The JVMCI Java initialization code will read this flag and 3813 // do the printing if it's set. 3814 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3815 3816 if (!force_JVMCI_intialization) { 3817 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3818 // compilations via JVMCI will not actually block until JVMCI is initialized. 3819 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3820 } 3821 } 3822 #endif 3823 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3824 // Postpone completion of compiler initialization to after JVMCI 3825 // is initialized to avoid timeouts of blocking compilations. 3826 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3827 CompileBroker::compilation_init_phase2(); 3828 } 3829 #endif 3830 3831 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3832 // It is done after compilers are initialized, because otherwise compilations of 3833 // signature polymorphic MH intrinsics can be missed 3834 // (see SystemDictionary::find_method_handle_intrinsic). 3835 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3836 3837 // This will initialize the module system. Only java.base classes can be 3838 // loaded until phase 2 completes 3839 call_initPhase2(CHECK_JNI_ERR); 3840 3841 // Always call even when there are not JVMTI environments yet, since environments 3842 // may be attached late and JVMTI must track phases of VM execution 3843 JvmtiExport::enter_start_phase(); 3844 3845 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3846 JvmtiExport::post_vm_start(); 3847 3848 // Final system initialization including security manager and system class loader 3849 call_initPhase3(CHECK_JNI_ERR); 3850 3851 // cache the system and platform class loaders 3852 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3853 3854 #if INCLUDE_CDS 3855 if (DumpSharedSpaces) { 3856 // capture the module path info from the ModuleEntryTable 3857 ClassLoader::initialize_module_path(THREAD); 3858 } 3859 #endif 3860 3861 #if INCLUDE_JVMCI 3862 if (force_JVMCI_intialization) { 3863 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3864 CompileBroker::compilation_init_phase2(); 3865 } 3866 #endif 3867 3868 // Always call even when there are not JVMTI environments yet, since environments 3869 // may be attached late and JVMTI must track phases of VM execution 3870 JvmtiExport::enter_live_phase(); 3871 3872 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3873 JvmtiExport::post_vm_initialized(); 3874 3875 JFR_ONLY(Jfr::on_vm_start();) 3876 3877 #if INCLUDE_MANAGEMENT 3878 Management::initialize(THREAD); 3879 3880 if (HAS_PENDING_EXCEPTION) { 3881 // management agent fails to start possibly due to 3882 // configuration problem and is responsible for printing 3883 // stack trace if appropriate. Simply exit VM. 3884 vm_exit(1); 3885 } 3886 #endif // INCLUDE_MANAGEMENT 3887 3888 if (MemProfiling) MemProfiler::engage(); 3889 StatSampler::engage(); 3890 if (CheckJNICalls) JniPeriodicChecker::engage(); 3891 3892 BiasedLocking::init(); 3893 3894 #if INCLUDE_RTM_OPT 3895 RTMLockingCounters::init(); 3896 #endif 3897 3898 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3899 call_postVMInitHook(THREAD); 3900 // The Java side of PostVMInitHook.run must deal with all 3901 // exceptions and provide means of diagnosis. 3902 if (HAS_PENDING_EXCEPTION) { 3903 CLEAR_PENDING_EXCEPTION; 3904 } 3905 } 3906 3907 { 3908 MutexLocker ml(PeriodicTask_lock); 3909 // Make sure the WatcherThread can be started by WatcherThread::start() 3910 // or by dynamic enrollment. 3911 WatcherThread::make_startable(); 3912 // Start up the WatcherThread if there are any periodic tasks 3913 // NOTE: All PeriodicTasks should be registered by now. If they 3914 // aren't, late joiners might appear to start slowly (we might 3915 // take a while to process their first tick). 3916 if (PeriodicTask::num_tasks() > 0) { 3917 WatcherThread::start(); 3918 } 3919 } 3920 3921 create_vm_timer.end(); 3922 #ifdef ASSERT 3923 _vm_complete = true; 3924 #endif 3925 3926 if (DumpSharedSpaces) { 3927 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3928 ShouldNotReachHere(); 3929 } 3930 3931 return JNI_OK; 3932 } 3933 3934 // type for the Agent_OnLoad and JVM_OnLoad entry points 3935 extern "C" { 3936 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3937 } 3938 // Find a command line agent library and return its entry point for 3939 // -agentlib: -agentpath: -Xrun 3940 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3941 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3942 const char *on_load_symbols[], 3943 size_t num_symbol_entries) { 3944 OnLoadEntry_t on_load_entry = NULL; 3945 void *library = NULL; 3946 3947 if (!agent->valid()) { 3948 char buffer[JVM_MAXPATHLEN]; 3949 char ebuf[1024] = ""; 3950 const char *name = agent->name(); 3951 const char *msg = "Could not find agent library "; 3952 3953 // First check to see if agent is statically linked into executable 3954 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3955 library = agent->os_lib(); 3956 } else if (agent->is_absolute_path()) { 3957 library = os::dll_load(name, ebuf, sizeof ebuf); 3958 if (library == NULL) { 3959 const char *sub_msg = " in absolute path, with error: "; 3960 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3961 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3962 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3963 // If we can't find the agent, exit. 3964 vm_exit_during_initialization(buf, NULL); 3965 FREE_C_HEAP_ARRAY(char, buf); 3966 } 3967 } else { 3968 // Try to load the agent from the standard dll directory 3969 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3970 name)) { 3971 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3972 } 3973 if (library == NULL) { // Try the library path directory. 3974 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 3975 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3976 } 3977 if (library == NULL) { 3978 const char *sub_msg = " on the library path, with error: "; 3979 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 3980 3981 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 3982 strlen(ebuf) + strlen(sub_msg2) + 1; 3983 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3984 if (!agent->is_instrument_lib()) { 3985 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3986 } else { 3987 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 3988 } 3989 // If we can't find the agent, exit. 3990 vm_exit_during_initialization(buf, NULL); 3991 FREE_C_HEAP_ARRAY(char, buf); 3992 } 3993 } 3994 } 3995 agent->set_os_lib(library); 3996 agent->set_valid(); 3997 } 3998 3999 // Find the OnLoad function. 4000 on_load_entry = 4001 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4002 false, 4003 on_load_symbols, 4004 num_symbol_entries)); 4005 return on_load_entry; 4006 } 4007 4008 // Find the JVM_OnLoad entry point 4009 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4010 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4011 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4012 } 4013 4014 // Find the Agent_OnLoad entry point 4015 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4016 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4017 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4018 } 4019 4020 // For backwards compatibility with -Xrun 4021 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4022 // treated like -agentpath: 4023 // Must be called before agent libraries are created 4024 void Threads::convert_vm_init_libraries_to_agents() { 4025 AgentLibrary* agent; 4026 AgentLibrary* next; 4027 4028 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4029 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4030 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4031 4032 // If there is an JVM_OnLoad function it will get called later, 4033 // otherwise see if there is an Agent_OnLoad 4034 if (on_load_entry == NULL) { 4035 on_load_entry = lookup_agent_on_load(agent); 4036 if (on_load_entry != NULL) { 4037 // switch it to the agent list -- so that Agent_OnLoad will be called, 4038 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4039 Arguments::convert_library_to_agent(agent); 4040 } else { 4041 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4042 } 4043 } 4044 } 4045 } 4046 4047 // Create agents for -agentlib: -agentpath: and converted -Xrun 4048 // Invokes Agent_OnLoad 4049 // Called very early -- before JavaThreads exist 4050 void Threads::create_vm_init_agents() { 4051 extern struct JavaVM_ main_vm; 4052 AgentLibrary* agent; 4053 4054 JvmtiExport::enter_onload_phase(); 4055 4056 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4057 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4058 4059 if (on_load_entry != NULL) { 4060 // Invoke the Agent_OnLoad function 4061 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4062 if (err != JNI_OK) { 4063 vm_exit_during_initialization("agent library failed to init", agent->name()); 4064 } 4065 } else { 4066 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4067 } 4068 } 4069 JvmtiExport::enter_primordial_phase(); 4070 } 4071 4072 extern "C" { 4073 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4074 } 4075 4076 void Threads::shutdown_vm_agents() { 4077 // Send any Agent_OnUnload notifications 4078 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4079 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4080 extern struct JavaVM_ main_vm; 4081 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4082 4083 // Find the Agent_OnUnload function. 4084 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4085 os::find_agent_function(agent, 4086 false, 4087 on_unload_symbols, 4088 num_symbol_entries)); 4089 4090 // Invoke the Agent_OnUnload function 4091 if (unload_entry != NULL) { 4092 JavaThread* thread = JavaThread::current(); 4093 ThreadToNativeFromVM ttn(thread); 4094 HandleMark hm(thread); 4095 (*unload_entry)(&main_vm); 4096 } 4097 } 4098 } 4099 4100 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4101 // Invokes JVM_OnLoad 4102 void Threads::create_vm_init_libraries() { 4103 extern struct JavaVM_ main_vm; 4104 AgentLibrary* agent; 4105 4106 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4107 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4108 4109 if (on_load_entry != NULL) { 4110 // Invoke the JVM_OnLoad function 4111 JavaThread* thread = JavaThread::current(); 4112 ThreadToNativeFromVM ttn(thread); 4113 HandleMark hm(thread); 4114 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4115 if (err != JNI_OK) { 4116 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4117 } 4118 } else { 4119 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4120 } 4121 } 4122 } 4123 4124 4125 // Last thread running calls java.lang.Shutdown.shutdown() 4126 void JavaThread::invoke_shutdown_hooks() { 4127 HandleMark hm(this); 4128 4129 // We could get here with a pending exception, if so clear it now. 4130 if (this->has_pending_exception()) { 4131 this->clear_pending_exception(); 4132 } 4133 4134 EXCEPTION_MARK; 4135 Klass* shutdown_klass = 4136 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4137 THREAD); 4138 if (shutdown_klass != NULL) { 4139 // SystemDictionary::resolve_or_null will return null if there was 4140 // an exception. If we cannot load the Shutdown class, just don't 4141 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4142 // won't be run. Note that if a shutdown hook was registered, 4143 // the Shutdown class would have already been loaded 4144 // (Runtime.addShutdownHook will load it). 4145 JavaValue result(T_VOID); 4146 JavaCalls::call_static(&result, 4147 shutdown_klass, 4148 vmSymbols::shutdown_method_name(), 4149 vmSymbols::void_method_signature(), 4150 THREAD); 4151 } 4152 CLEAR_PENDING_EXCEPTION; 4153 } 4154 4155 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4156 // the program falls off the end of main(). Another VM exit path is through 4157 // vm_exit() when the program calls System.exit() to return a value or when 4158 // there is a serious error in VM. The two shutdown paths are not exactly 4159 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4160 // and VM_Exit op at VM level. 4161 // 4162 // Shutdown sequence: 4163 // + Shutdown native memory tracking if it is on 4164 // + Wait until we are the last non-daemon thread to execute 4165 // <-- every thing is still working at this moment --> 4166 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4167 // shutdown hooks 4168 // + Call before_exit(), prepare for VM exit 4169 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4170 // currently the only user of this mechanism is File.deleteOnExit()) 4171 // > stop StatSampler, watcher thread, CMS threads, 4172 // post thread end and vm death events to JVMTI, 4173 // stop signal thread 4174 // + Call JavaThread::exit(), it will: 4175 // > release JNI handle blocks, remove stack guard pages 4176 // > remove this thread from Threads list 4177 // <-- no more Java code from this thread after this point --> 4178 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4179 // the compiler threads at safepoint 4180 // <-- do not use anything that could get blocked by Safepoint --> 4181 // + Disable tracing at JNI/JVM barriers 4182 // + Set _vm_exited flag for threads that are still running native code 4183 // + Delete this thread 4184 // + Call exit_globals() 4185 // > deletes tty 4186 // > deletes PerfMemory resources 4187 // + Return to caller 4188 4189 bool Threads::destroy_vm() { 4190 JavaThread* thread = JavaThread::current(); 4191 4192 #ifdef ASSERT 4193 _vm_complete = false; 4194 #endif 4195 // Wait until we are the last non-daemon thread to execute 4196 { MutexLocker nu(Threads_lock); 4197 while (Threads::number_of_non_daemon_threads() > 1) 4198 // This wait should make safepoint checks, wait without a timeout, 4199 // and wait as a suspend-equivalent condition. 4200 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4201 Mutex::_as_suspend_equivalent_flag); 4202 } 4203 4204 EventShutdown e; 4205 if (e.should_commit()) { 4206 e.set_reason("No remaining non-daemon Java threads"); 4207 e.commit(); 4208 } 4209 4210 // Hang forever on exit if we are reporting an error. 4211 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4212 os::infinite_sleep(); 4213 } 4214 os::wait_for_keypress_at_exit(); 4215 4216 // run Java level shutdown hooks 4217 thread->invoke_shutdown_hooks(); 4218 4219 before_exit(thread); 4220 4221 thread->exit(true); 4222 // thread will never call smr_delete, instead of implicit cancel 4223 // in wait_for_vm_thread_exit we do it explicit. 4224 thread->cancel_handshake(); 4225 4226 // Stop VM thread. 4227 { 4228 // 4945125 The vm thread comes to a safepoint during exit. 4229 // GC vm_operations can get caught at the safepoint, and the 4230 // heap is unparseable if they are caught. Grab the Heap_lock 4231 // to prevent this. The GC vm_operations will not be able to 4232 // queue until after the vm thread is dead. After this point, 4233 // we'll never emerge out of the safepoint before the VM exits. 4234 4235 MutexLocker ml(Heap_lock); 4236 4237 VMThread::wait_for_vm_thread_exit(); 4238 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4239 VMThread::destroy(); 4240 } 4241 4242 // Now, all Java threads are gone except daemon threads. Daemon threads 4243 // running Java code or in VM are stopped by the Safepoint. However, 4244 // daemon threads executing native code are still running. But they 4245 // will be stopped at native=>Java/VM barriers. Note that we can't 4246 // simply kill or suspend them, as it is inherently deadlock-prone. 4247 4248 VM_Exit::set_vm_exited(); 4249 4250 // Clean up ideal graph printers after the VMThread has started 4251 // the final safepoint which will block all the Compiler threads. 4252 // Note that this Thread has already logically exited so the 4253 // clean_up() function's use of a JavaThreadIteratorWithHandle 4254 // would be a problem except set_vm_exited() has remembered the 4255 // shutdown thread which is granted a policy exception. 4256 #if defined(COMPILER2) && !defined(PRODUCT) 4257 IdealGraphPrinter::clean_up(); 4258 #endif 4259 4260 notify_vm_shutdown(); 4261 4262 // We are after VM_Exit::set_vm_exited() so we can't call 4263 // thread->smr_delete() or we will block on the Threads_lock. 4264 // Deleting the shutdown thread here is safe because another 4265 // JavaThread cannot have an active ThreadsListHandle for 4266 // this JavaThread. 4267 delete thread; 4268 4269 #if INCLUDE_JVMCI 4270 if (JVMCICounterSize > 0) { 4271 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4272 } 4273 #endif 4274 4275 // exit_globals() will delete tty 4276 exit_globals(); 4277 4278 LogConfiguration::finalize(); 4279 4280 return true; 4281 } 4282 4283 4284 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4285 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4286 return is_supported_jni_version(version); 4287 } 4288 4289 4290 jboolean Threads::is_supported_jni_version(jint version) { 4291 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4292 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4293 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4294 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4295 if (version == JNI_VERSION_9) return JNI_TRUE; 4296 if (version == JNI_VERSION_10) return JNI_TRUE; 4297 return JNI_FALSE; 4298 } 4299 4300 4301 void Threads::add(JavaThread* p, bool force_daemon) { 4302 // The threads lock must be owned at this point 4303 assert_locked_or_safepoint(Threads_lock); 4304 4305 BarrierSet::barrier_set()->on_thread_attach(p); 4306 4307 p->set_next(_thread_list); 4308 _thread_list = p; 4309 4310 // Once a JavaThread is added to the Threads list, smr_delete() has 4311 // to be used to delete it. Otherwise we can just delete it directly. 4312 p->set_on_thread_list(); 4313 4314 _number_of_threads++; 4315 oop threadObj = p->threadObj(); 4316 bool daemon = true; 4317 // Bootstrapping problem: threadObj can be null for initial 4318 // JavaThread (or for threads attached via JNI) 4319 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4320 _number_of_non_daemon_threads++; 4321 daemon = false; 4322 } 4323 4324 ThreadService::add_thread(p, daemon); 4325 4326 // Maintain fast thread list 4327 ThreadsSMRSupport::add_thread(p); 4328 4329 // Possible GC point. 4330 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4331 } 4332 4333 void Threads::remove(JavaThread* p) { 4334 4335 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4336 ObjectSynchronizer::omFlush(p); 4337 4338 // Extra scope needed for Thread_lock, so we can check 4339 // that we do not remove thread without safepoint code notice 4340 { MutexLocker ml(Threads_lock); 4341 4342 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4343 4344 // Maintain fast thread list 4345 ThreadsSMRSupport::remove_thread(p); 4346 4347 JavaThread* current = _thread_list; 4348 JavaThread* prev = NULL; 4349 4350 while (current != p) { 4351 prev = current; 4352 current = current->next(); 4353 } 4354 4355 if (prev) { 4356 prev->set_next(current->next()); 4357 } else { 4358 _thread_list = p->next(); 4359 } 4360 4361 _number_of_threads--; 4362 oop threadObj = p->threadObj(); 4363 bool daemon = true; 4364 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4365 _number_of_non_daemon_threads--; 4366 daemon = false; 4367 4368 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4369 // on destroy_vm will wake up. 4370 if (number_of_non_daemon_threads() == 1) { 4371 Threads_lock->notify_all(); 4372 } 4373 } 4374 ThreadService::remove_thread(p, daemon); 4375 4376 // Make sure that safepoint code disregard this thread. This is needed since 4377 // the thread might mess around with locks after this point. This can cause it 4378 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4379 // of this thread since it is removed from the queue. 4380 p->set_terminated_value(); 4381 } // unlock Threads_lock 4382 4383 // Since Events::log uses a lock, we grab it outside the Threads_lock 4384 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4385 } 4386 4387 // Operations on the Threads list for GC. These are not explicitly locked, 4388 // but the garbage collector must provide a safe context for them to run. 4389 // In particular, these things should never be called when the Threads_lock 4390 // is held by some other thread. (Note: the Safepoint abstraction also 4391 // uses the Threads_lock to guarantee this property. It also makes sure that 4392 // all threads gets blocked when exiting or starting). 4393 4394 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4395 ALL_JAVA_THREADS(p) { 4396 p->oops_do(f, cf); 4397 } 4398 VMThread::vm_thread()->oops_do(f, cf); 4399 } 4400 4401 void Threads::change_thread_claim_parity() { 4402 // Set the new claim parity. 4403 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4404 "Not in range."); 4405 _thread_claim_parity++; 4406 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4407 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4408 "Not in range."); 4409 } 4410 4411 #ifdef ASSERT 4412 void Threads::assert_all_threads_claimed() { 4413 ALL_JAVA_THREADS(p) { 4414 const int thread_parity = p->oops_do_parity(); 4415 assert((thread_parity == _thread_claim_parity), 4416 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4417 } 4418 VMThread* vmt = VMThread::vm_thread(); 4419 const int thread_parity = vmt->oops_do_parity(); 4420 assert((thread_parity == _thread_claim_parity), 4421 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4422 } 4423 #endif // ASSERT 4424 4425 class ParallelOopsDoThreadClosure : public ThreadClosure { 4426 private: 4427 OopClosure* _f; 4428 CodeBlobClosure* _cf; 4429 public: 4430 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4431 void do_thread(Thread* t) { 4432 t->oops_do(_f, _cf); 4433 } 4434 }; 4435 4436 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4437 ParallelOopsDoThreadClosure tc(f, cf); 4438 possibly_parallel_threads_do(is_par, &tc); 4439 } 4440 4441 void Threads::nmethods_do(CodeBlobClosure* cf) { 4442 ALL_JAVA_THREADS(p) { 4443 // This is used by the code cache sweeper to mark nmethods that are active 4444 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4445 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4446 if(!p->is_Code_cache_sweeper_thread()) { 4447 p->nmethods_do(cf); 4448 } 4449 } 4450 } 4451 4452 void Threads::metadata_do(void f(Metadata*)) { 4453 ALL_JAVA_THREADS(p) { 4454 p->metadata_do(f); 4455 } 4456 } 4457 4458 class ThreadHandlesClosure : public ThreadClosure { 4459 void (*_f)(Metadata*); 4460 public: 4461 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4462 virtual void do_thread(Thread* thread) { 4463 thread->metadata_handles_do(_f); 4464 } 4465 }; 4466 4467 void Threads::metadata_handles_do(void f(Metadata*)) { 4468 // Only walk the Handles in Thread. 4469 ThreadHandlesClosure handles_closure(f); 4470 threads_do(&handles_closure); 4471 } 4472 4473 void Threads::deoptimized_wrt_marked_nmethods() { 4474 ALL_JAVA_THREADS(p) { 4475 p->deoptimized_wrt_marked_nmethods(); 4476 } 4477 } 4478 4479 4480 // Get count Java threads that are waiting to enter the specified monitor. 4481 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4482 int count, 4483 address monitor) { 4484 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4485 4486 int i = 0; 4487 DO_JAVA_THREADS(t_list, p) { 4488 if (!p->can_call_java()) continue; 4489 4490 address pending = (address)p->current_pending_monitor(); 4491 if (pending == monitor) { // found a match 4492 if (i < count) result->append(p); // save the first count matches 4493 i++; 4494 } 4495 } 4496 4497 return result; 4498 } 4499 4500 4501 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4502 address owner) { 4503 // NULL owner means not locked so we can skip the search 4504 if (owner == NULL) return NULL; 4505 4506 DO_JAVA_THREADS(t_list, p) { 4507 // first, see if owner is the address of a Java thread 4508 if (owner == (address)p) return p; 4509 } 4510 4511 // Cannot assert on lack of success here since this function may be 4512 // used by code that is trying to report useful problem information 4513 // like deadlock detection. 4514 if (UseHeavyMonitors) return NULL; 4515 4516 // If we didn't find a matching Java thread and we didn't force use of 4517 // heavyweight monitors, then the owner is the stack address of the 4518 // Lock Word in the owning Java thread's stack. 4519 // 4520 JavaThread* the_owner = NULL; 4521 DO_JAVA_THREADS(t_list, q) { 4522 if (q->is_lock_owned(owner)) { 4523 the_owner = q; 4524 break; 4525 } 4526 } 4527 4528 // cannot assert on lack of success here; see above comment 4529 return the_owner; 4530 } 4531 4532 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4533 void Threads::print_on(outputStream* st, bool print_stacks, 4534 bool internal_format, bool print_concurrent_locks) { 4535 char buf[32]; 4536 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4537 4538 st->print_cr("Full thread dump %s (%s %s):", 4539 Abstract_VM_Version::vm_name(), 4540 Abstract_VM_Version::vm_release(), 4541 Abstract_VM_Version::vm_info_string()); 4542 st->cr(); 4543 4544 #if INCLUDE_SERVICES 4545 // Dump concurrent locks 4546 ConcurrentLocksDump concurrent_locks; 4547 if (print_concurrent_locks) { 4548 concurrent_locks.dump_at_safepoint(); 4549 } 4550 #endif // INCLUDE_SERVICES 4551 4552 ThreadsSMRSupport::print_info_on(st); 4553 st->cr(); 4554 4555 ALL_JAVA_THREADS(p) { 4556 ResourceMark rm; 4557 p->print_on(st); 4558 if (print_stacks) { 4559 if (internal_format) { 4560 p->trace_stack(); 4561 } else { 4562 p->print_stack_on(st); 4563 } 4564 } 4565 st->cr(); 4566 #if INCLUDE_SERVICES 4567 if (print_concurrent_locks) { 4568 concurrent_locks.print_locks_on(p, st); 4569 } 4570 #endif // INCLUDE_SERVICES 4571 } 4572 4573 VMThread::vm_thread()->print_on(st); 4574 st->cr(); 4575 Universe::heap()->print_gc_threads_on(st); 4576 WatcherThread* wt = WatcherThread::watcher_thread(); 4577 if (wt != NULL) { 4578 wt->print_on(st); 4579 st->cr(); 4580 } 4581 4582 st->flush(); 4583 } 4584 4585 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4586 int buflen, bool* found_current) { 4587 if (this_thread != NULL) { 4588 bool is_current = (current == this_thread); 4589 *found_current = *found_current || is_current; 4590 st->print("%s", is_current ? "=>" : " "); 4591 4592 st->print(PTR_FORMAT, p2i(this_thread)); 4593 st->print(" "); 4594 this_thread->print_on_error(st, buf, buflen); 4595 st->cr(); 4596 } 4597 } 4598 4599 class PrintOnErrorClosure : public ThreadClosure { 4600 outputStream* _st; 4601 Thread* _current; 4602 char* _buf; 4603 int _buflen; 4604 bool* _found_current; 4605 public: 4606 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4607 int buflen, bool* found_current) : 4608 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4609 4610 virtual void do_thread(Thread* thread) { 4611 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4612 } 4613 }; 4614 4615 // Threads::print_on_error() is called by fatal error handler. It's possible 4616 // that VM is not at safepoint and/or current thread is inside signal handler. 4617 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4618 // memory (even in resource area), it might deadlock the error handler. 4619 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4620 int buflen) { 4621 ThreadsSMRSupport::print_info_on(st); 4622 st->cr(); 4623 4624 bool found_current = false; 4625 st->print_cr("Java Threads: ( => current thread )"); 4626 ALL_JAVA_THREADS(thread) { 4627 print_on_error(thread, st, current, buf, buflen, &found_current); 4628 } 4629 st->cr(); 4630 4631 st->print_cr("Other Threads:"); 4632 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4633 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4634 4635 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4636 Universe::heap()->gc_threads_do(&print_closure); 4637 4638 if (!found_current) { 4639 st->cr(); 4640 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4641 current->print_on_error(st, buf, buflen); 4642 st->cr(); 4643 } 4644 st->cr(); 4645 4646 st->print_cr("Threads with active compile tasks:"); 4647 print_threads_compiling(st, buf, buflen); 4648 } 4649 4650 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4651 ALL_JAVA_THREADS(thread) { 4652 if (thread->is_Compiler_thread()) { 4653 CompilerThread* ct = (CompilerThread*) thread; 4654 4655 // Keep task in local variable for NULL check. 4656 // ct->_task might be set to NULL by concurring compiler thread 4657 // because it completed the compilation. The task is never freed, 4658 // though, just returned to a free list. 4659 CompileTask* task = ct->task(); 4660 if (task != NULL) { 4661 thread->print_name_on_error(st, buf, buflen); 4662 task->print(st, NULL, true, true); 4663 } 4664 } 4665 } 4666 } 4667 4668 4669 // Internal SpinLock and Mutex 4670 // Based on ParkEvent 4671 4672 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4673 // 4674 // We employ SpinLocks _only for low-contention, fixed-length 4675 // short-duration critical sections where we're concerned 4676 // about native mutex_t or HotSpot Mutex:: latency. 4677 // The mux construct provides a spin-then-block mutual exclusion 4678 // mechanism. 4679 // 4680 // Testing has shown that contention on the ListLock guarding gFreeList 4681 // is common. If we implement ListLock as a simple SpinLock it's common 4682 // for the JVM to devolve to yielding with little progress. This is true 4683 // despite the fact that the critical sections protected by ListLock are 4684 // extremely short. 4685 // 4686 // TODO-FIXME: ListLock should be of type SpinLock. 4687 // We should make this a 1st-class type, integrated into the lock 4688 // hierarchy as leaf-locks. Critically, the SpinLock structure 4689 // should have sufficient padding to avoid false-sharing and excessive 4690 // cache-coherency traffic. 4691 4692 4693 typedef volatile int SpinLockT; 4694 4695 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4696 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4697 return; // normal fast-path return 4698 } 4699 4700 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4701 TEVENT(SpinAcquire - ctx); 4702 int ctr = 0; 4703 int Yields = 0; 4704 for (;;) { 4705 while (*adr != 0) { 4706 ++ctr; 4707 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4708 if (Yields > 5) { 4709 os::naked_short_sleep(1); 4710 } else { 4711 os::naked_yield(); 4712 ++Yields; 4713 } 4714 } else { 4715 SpinPause(); 4716 } 4717 } 4718 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4719 } 4720 } 4721 4722 void Thread::SpinRelease(volatile int * adr) { 4723 assert(*adr != 0, "invariant"); 4724 OrderAccess::fence(); // guarantee at least release consistency. 4725 // Roach-motel semantics. 4726 // It's safe if subsequent LDs and STs float "up" into the critical section, 4727 // but prior LDs and STs within the critical section can't be allowed 4728 // to reorder or float past the ST that releases the lock. 4729 // Loads and stores in the critical section - which appear in program 4730 // order before the store that releases the lock - must also appear 4731 // before the store that releases the lock in memory visibility order. 4732 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4733 // the ST of 0 into the lock-word which releases the lock, so fence 4734 // more than covers this on all platforms. 4735 *adr = 0; 4736 } 4737 4738 // muxAcquire and muxRelease: 4739 // 4740 // * muxAcquire and muxRelease support a single-word lock-word construct. 4741 // The LSB of the word is set IFF the lock is held. 4742 // The remainder of the word points to the head of a singly-linked list 4743 // of threads blocked on the lock. 4744 // 4745 // * The current implementation of muxAcquire-muxRelease uses its own 4746 // dedicated Thread._MuxEvent instance. If we're interested in 4747 // minimizing the peak number of extant ParkEvent instances then 4748 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4749 // as certain invariants were satisfied. Specifically, care would need 4750 // to be taken with regards to consuming unpark() "permits". 4751 // A safe rule of thumb is that a thread would never call muxAcquire() 4752 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4753 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4754 // consume an unpark() permit intended for monitorenter, for instance. 4755 // One way around this would be to widen the restricted-range semaphore 4756 // implemented in park(). Another alternative would be to provide 4757 // multiple instances of the PlatformEvent() for each thread. One 4758 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4759 // 4760 // * Usage: 4761 // -- Only as leaf locks 4762 // -- for short-term locking only as muxAcquire does not perform 4763 // thread state transitions. 4764 // 4765 // Alternatives: 4766 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4767 // but with parking or spin-then-park instead of pure spinning. 4768 // * Use Taura-Oyama-Yonenzawa locks. 4769 // * It's possible to construct a 1-0 lock if we encode the lockword as 4770 // (List,LockByte). Acquire will CAS the full lockword while Release 4771 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4772 // acquiring threads use timers (ParkTimed) to detect and recover from 4773 // the stranding window. Thread/Node structures must be aligned on 256-byte 4774 // boundaries by using placement-new. 4775 // * Augment MCS with advisory back-link fields maintained with CAS(). 4776 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4777 // The validity of the backlinks must be ratified before we trust the value. 4778 // If the backlinks are invalid the exiting thread must back-track through the 4779 // the forward links, which are always trustworthy. 4780 // * Add a successor indication. The LockWord is currently encoded as 4781 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4782 // to provide the usual futile-wakeup optimization. 4783 // See RTStt for details. 4784 // * Consider schedctl.sc_nopreempt to cover the critical section. 4785 // 4786 4787 4788 const intptr_t LOCKBIT = 1; 4789 4790 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4791 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4792 if (w == 0) return; 4793 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4794 return; 4795 } 4796 4797 TEVENT(muxAcquire - Contention); 4798 ParkEvent * const Self = Thread::current()->_MuxEvent; 4799 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4800 for (;;) { 4801 int its = (os::is_MP() ? 100 : 0) + 1; 4802 4803 // Optional spin phase: spin-then-park strategy 4804 while (--its >= 0) { 4805 w = *Lock; 4806 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4807 return; 4808 } 4809 } 4810 4811 Self->reset(); 4812 Self->OnList = intptr_t(Lock); 4813 // The following fence() isn't _strictly necessary as the subsequent 4814 // CAS() both serializes execution and ratifies the fetched *Lock value. 4815 OrderAccess::fence(); 4816 for (;;) { 4817 w = *Lock; 4818 if ((w & LOCKBIT) == 0) { 4819 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4820 Self->OnList = 0; // hygiene - allows stronger asserts 4821 return; 4822 } 4823 continue; // Interference -- *Lock changed -- Just retry 4824 } 4825 assert(w & LOCKBIT, "invariant"); 4826 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4827 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4828 } 4829 4830 while (Self->OnList != 0) { 4831 Self->park(); 4832 } 4833 } 4834 } 4835 4836 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4837 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4838 if (w == 0) return; 4839 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4840 return; 4841 } 4842 4843 TEVENT(muxAcquire - Contention); 4844 ParkEvent * ReleaseAfter = NULL; 4845 if (ev == NULL) { 4846 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4847 } 4848 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4849 for (;;) { 4850 guarantee(ev->OnList == 0, "invariant"); 4851 int its = (os::is_MP() ? 100 : 0) + 1; 4852 4853 // Optional spin phase: spin-then-park strategy 4854 while (--its >= 0) { 4855 w = *Lock; 4856 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4857 if (ReleaseAfter != NULL) { 4858 ParkEvent::Release(ReleaseAfter); 4859 } 4860 return; 4861 } 4862 } 4863 4864 ev->reset(); 4865 ev->OnList = intptr_t(Lock); 4866 // The following fence() isn't _strictly necessary as the subsequent 4867 // CAS() both serializes execution and ratifies the fetched *Lock value. 4868 OrderAccess::fence(); 4869 for (;;) { 4870 w = *Lock; 4871 if ((w & LOCKBIT) == 0) { 4872 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4873 ev->OnList = 0; 4874 // We call ::Release while holding the outer lock, thus 4875 // artificially lengthening the critical section. 4876 // Consider deferring the ::Release() until the subsequent unlock(), 4877 // after we've dropped the outer lock. 4878 if (ReleaseAfter != NULL) { 4879 ParkEvent::Release(ReleaseAfter); 4880 } 4881 return; 4882 } 4883 continue; // Interference -- *Lock changed -- Just retry 4884 } 4885 assert(w & LOCKBIT, "invariant"); 4886 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4887 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4888 } 4889 4890 while (ev->OnList != 0) { 4891 ev->park(); 4892 } 4893 } 4894 } 4895 4896 // Release() must extract a successor from the list and then wake that thread. 4897 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4898 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4899 // Release() would : 4900 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4901 // (B) Extract a successor from the private list "in-hand" 4902 // (C) attempt to CAS() the residual back into *Lock over null. 4903 // If there were any newly arrived threads and the CAS() would fail. 4904 // In that case Release() would detach the RATs, re-merge the list in-hand 4905 // with the RATs and repeat as needed. Alternately, Release() might 4906 // detach and extract a successor, but then pass the residual list to the wakee. 4907 // The wakee would be responsible for reattaching and remerging before it 4908 // competed for the lock. 4909 // 4910 // Both "pop" and DMR are immune from ABA corruption -- there can be 4911 // multiple concurrent pushers, but only one popper or detacher. 4912 // This implementation pops from the head of the list. This is unfair, 4913 // but tends to provide excellent throughput as hot threads remain hot. 4914 // (We wake recently run threads first). 4915 // 4916 // All paths through muxRelease() will execute a CAS. 4917 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4918 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4919 // executed within the critical section are complete and globally visible before the 4920 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4921 void Thread::muxRelease(volatile intptr_t * Lock) { 4922 for (;;) { 4923 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4924 assert(w & LOCKBIT, "invariant"); 4925 if (w == LOCKBIT) return; 4926 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4927 assert(List != NULL, "invariant"); 4928 assert(List->OnList == intptr_t(Lock), "invariant"); 4929 ParkEvent * const nxt = List->ListNext; 4930 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4931 4932 // The following CAS() releases the lock and pops the head element. 4933 // The CAS() also ratifies the previously fetched lock-word value. 4934 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4935 continue; 4936 } 4937 List->OnList = 0; 4938 OrderAccess::fence(); 4939 List->unpark(); 4940 return; 4941 } 4942 } 4943 4944 4945 void Threads::verify() { 4946 ALL_JAVA_THREADS(p) { 4947 p->verify(); 4948 } 4949 VMThread* thread = VMThread::vm_thread(); 4950 if (thread != NULL) thread->verify(); 4951 }