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/threadStatisticalInfo.hpp" 97 #include "runtime/timer.hpp" 98 #include "runtime/timerTrace.hpp" 99 #include "runtime/vframe.inline.hpp" 100 #include "runtime/vframeArray.hpp" 101 #include "runtime/vframe_hp.hpp" 102 #include "runtime/vmThread.hpp" 103 #include "runtime/vm_operations.hpp" 104 #include "runtime/vm_version.hpp" 105 #include "services/attachListener.hpp" 106 #include "services/management.hpp" 107 #include "services/memTracker.hpp" 108 #include "services/threadService.hpp" 109 #include "utilities/align.hpp" 110 #include "utilities/copy.hpp" 111 #include "utilities/defaultStream.hpp" 112 #include "utilities/dtrace.hpp" 113 #include "utilities/events.hpp" 114 #include "utilities/macros.hpp" 115 #include "utilities/preserveException.hpp" 116 #include "utilities/vmError.hpp" 117 #if INCLUDE_JVMCI 118 #include "jvmci/jvmciCompiler.hpp" 119 #include "jvmci/jvmciRuntime.hpp" 120 #include "logging/logHandle.hpp" 121 #endif 122 #ifdef COMPILER1 123 #include "c1/c1_Compiler.hpp" 124 #endif 125 #ifdef COMPILER2 126 #include "opto/c2compiler.hpp" 127 #include "opto/idealGraphPrinter.hpp" 128 #endif 129 #if INCLUDE_RTM_OPT 130 #include "runtime/rtmLocking.hpp" 131 #endif 132 #if INCLUDE_JFR 133 #include "jfr/jfr.hpp" 134 #endif 135 136 // Initialization after module runtime initialization 137 void universe_post_module_init(); // must happen after call_initPhase2 138 139 #ifdef DTRACE_ENABLED 140 141 // Only bother with this argument setup if dtrace is available 142 143 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 144 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 145 146 #define DTRACE_THREAD_PROBE(probe, javathread) \ 147 { \ 148 ResourceMark rm(this); \ 149 int len = 0; \ 150 const char* name = (javathread)->get_thread_name(); \ 151 len = strlen(name); \ 152 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 153 (char *) name, len, \ 154 java_lang_Thread::thread_id((javathread)->threadObj()), \ 155 (uintptr_t) (javathread)->osthread()->thread_id(), \ 156 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 157 } 158 159 #else // ndef DTRACE_ENABLED 160 161 #define DTRACE_THREAD_PROBE(probe, javathread) 162 163 #endif // ndef DTRACE_ENABLED 164 165 #ifndef USE_LIBRARY_BASED_TLS_ONLY 166 // Current thread is maintained as a thread-local variable 167 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 168 #endif 169 // Class hierarchy 170 // - Thread 171 // - VMThread 172 // - WatcherThread 173 // - ConcurrentMarkSweepThread 174 // - JavaThread 175 // - CompilerThread 176 177 // ======= Thread ======== 178 // Support for forcing alignment of thread objects for biased locking 179 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 180 if (UseBiasedLocking) { 181 const int alignment = markOopDesc::biased_lock_alignment; 182 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 183 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 184 : AllocateHeap(aligned_size, flags, CURRENT_PC, 185 AllocFailStrategy::RETURN_NULL); 186 void* aligned_addr = align_up(real_malloc_addr, alignment); 187 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 188 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 189 "JavaThread alignment code overflowed allocated storage"); 190 if (aligned_addr != real_malloc_addr) { 191 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 192 p2i(real_malloc_addr), 193 p2i(aligned_addr)); 194 } 195 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 196 return aligned_addr; 197 } else { 198 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 199 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 200 } 201 } 202 203 void Thread::operator delete(void* p) { 204 if (UseBiasedLocking) { 205 FreeHeap(((Thread*) p)->_real_malloc_address); 206 } else { 207 FreeHeap(p); 208 } 209 } 210 211 void JavaThread::smr_delete() { 212 if (_on_thread_list) { 213 ThreadsSMRSupport::smr_delete(this); 214 } else { 215 delete this; 216 } 217 } 218 219 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 220 // JavaThread 221 222 223 Thread::Thread() { 224 // stack and get_thread 225 set_stack_base(NULL); 226 set_stack_size(0); 227 set_self_raw_id(0); 228 set_lgrp_id(-1); 229 DEBUG_ONLY(clear_suspendible_thread();) 230 231 // allocated data structures 232 set_osthread(NULL); 233 set_resource_area(new (mtThread)ResourceArea()); 234 DEBUG_ONLY(_current_resource_mark = NULL;) 235 set_handle_area(new (mtThread) HandleArea(NULL)); 236 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 237 set_active_handles(NULL); 238 set_free_handle_block(NULL); 239 set_last_handle_mark(NULL); 240 241 // This initial value ==> never claimed. 242 _oops_do_parity = 0; 243 _threads_hazard_ptr = NULL; 244 _threads_list_ptr = NULL; 245 _nested_threads_hazard_ptr_cnt = 0; 246 _rcu_counter = 0; 247 248 // the handle mark links itself to last_handle_mark 249 new HandleMark(this); 250 251 // plain initialization 252 debug_only(_owned_locks = NULL;) 253 debug_only(_allow_allocation_count = 0;) 254 NOT_PRODUCT(_allow_safepoint_count = 0;) 255 NOT_PRODUCT(_skip_gcalot = false;) 256 _jvmti_env_iteration_count = 0; 257 set_allocated_bytes(0); 258 _vm_operation_started_count = 0; 259 _vm_operation_completed_count = 0; 260 _current_pending_monitor = NULL; 261 _current_pending_monitor_is_from_java = true; 262 _current_waiting_monitor = NULL; 263 _num_nested_signal = 0; 264 omFreeList = NULL; 265 omFreeCount = 0; 266 omFreeProvision = 32; 267 omInUseList = NULL; 268 omInUseCount = 0; 269 270 #ifdef ASSERT 271 _visited_for_critical_count = false; 272 #endif 273 274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 275 Monitor::_safepoint_check_sometimes); 276 _suspend_flags = 0; 277 278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 279 _hashStateX = os::random(); 280 _hashStateY = 842502087; 281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 282 _hashStateW = 273326509; 283 284 _OnTrap = 0; 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, bool print_extended_info) 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 } 879 880 st->print("cpu=%.2fms ", 881 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 882 ); 883 st->print("elapsed=%.2fs ", 884 _statistical_info.getElapsedTime() / 1000.0 885 ); 886 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 887 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 888 st->print("allocated=" SIZE_FORMAT "%s ", 889 byte_size_in_proper_unit(allocated_bytes), 890 proper_unit_for_byte_size(allocated_bytes) 891 ); 892 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 893 } 894 895 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 896 osthread()->print_on(st); 897 } 898 ThreadsSMRSupport::print_info_on(this, st); 899 st->print(" "); 900 debug_only(if (WizardMode) print_owned_locks_on(st);) 901 } 902 903 // Thread::print_on_error() is called by fatal error handler. Don't use 904 // any lock or allocate memory. 905 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 906 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 907 908 if (is_VM_thread()) { st->print("VMThread"); } 909 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 910 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 911 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 912 else { st->print("Thread"); } 913 914 if (is_Named_thread()) { 915 st->print(" \"%s\"", name()); 916 } 917 918 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 919 p2i(stack_end()), p2i(stack_base())); 920 921 if (osthread()) { 922 st->print(" [id=%d]", osthread()->thread_id()); 923 } 924 925 ThreadsSMRSupport::print_info_on(this, st); 926 } 927 928 void Thread::print_value_on(outputStream* st) const { 929 if (is_Named_thread()) { 930 st->print(" \"%s\" ", name()); 931 } 932 st->print(INTPTR_FORMAT, p2i(this)); // print address 933 } 934 935 #ifdef ASSERT 936 void Thread::print_owned_locks_on(outputStream* st) const { 937 Monitor *cur = _owned_locks; 938 if (cur == NULL) { 939 st->print(" (no locks) "); 940 } else { 941 st->print_cr(" Locks owned:"); 942 while (cur) { 943 cur->print_on(st); 944 cur = cur->next(); 945 } 946 } 947 } 948 949 static int ref_use_count = 0; 950 951 bool Thread::owns_locks_but_compiled_lock() const { 952 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 953 if (cur != Compile_lock) return true; 954 } 955 return false; 956 } 957 958 959 #endif 960 961 #ifndef PRODUCT 962 963 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 964 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 965 // no locks which allow_vm_block's are held 966 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 967 // Check if current thread is allowed to block at a safepoint 968 if (!(_allow_safepoint_count == 0)) { 969 fatal("Possible safepoint reached by thread that does not allow it"); 970 } 971 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 972 fatal("LEAF method calling lock?"); 973 } 974 975 #ifdef ASSERT 976 if (potential_vm_operation && is_Java_thread() 977 && !Universe::is_bootstrapping()) { 978 // Make sure we do not hold any locks that the VM thread also uses. 979 // This could potentially lead to deadlocks 980 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 981 // Threads_lock is special, since the safepoint synchronization will not start before this is 982 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 983 // since it is used to transfer control between JavaThreads and the VMThread 984 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 985 if ((cur->allow_vm_block() && 986 cur != Threads_lock && 987 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 988 cur != VMOperationRequest_lock && 989 cur != VMOperationQueue_lock) || 990 cur->rank() == Mutex::special) { 991 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 992 } 993 } 994 } 995 996 if (GCALotAtAllSafepoints) { 997 // We could enter a safepoint here and thus have a gc 998 InterfaceSupport::check_gc_alot(); 999 } 1000 #endif 1001 } 1002 #endif 1003 1004 bool Thread::is_in_stack(address adr) const { 1005 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1006 address end = os::current_stack_pointer(); 1007 // Allow non Java threads to call this without stack_base 1008 if (_stack_base == NULL) return true; 1009 if (stack_base() >= adr && adr >= end) return true; 1010 1011 return false; 1012 } 1013 1014 bool Thread::is_in_usable_stack(address adr) const { 1015 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1016 size_t usable_stack_size = _stack_size - stack_guard_size; 1017 1018 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1019 } 1020 1021 1022 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1023 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1024 // used for compilation in the future. If that change is made, the need for these methods 1025 // should be revisited, and they should be removed if possible. 1026 1027 bool Thread::is_lock_owned(address adr) const { 1028 return on_local_stack(adr); 1029 } 1030 1031 bool Thread::set_as_starting_thread() { 1032 // NOTE: this must be called inside the main thread. 1033 return os::create_main_thread((JavaThread*)this); 1034 } 1035 1036 static void initialize_class(Symbol* class_name, TRAPS) { 1037 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1038 InstanceKlass::cast(klass)->initialize(CHECK); 1039 } 1040 1041 1042 // Creates the initial ThreadGroup 1043 static Handle create_initial_thread_group(TRAPS) { 1044 Handle system_instance = JavaCalls::construct_new_instance( 1045 SystemDictionary::ThreadGroup_klass(), 1046 vmSymbols::void_method_signature(), 1047 CHECK_NH); 1048 Universe::set_system_thread_group(system_instance()); 1049 1050 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1051 Handle main_instance = JavaCalls::construct_new_instance( 1052 SystemDictionary::ThreadGroup_klass(), 1053 vmSymbols::threadgroup_string_void_signature(), 1054 system_instance, 1055 string, 1056 CHECK_NH); 1057 return main_instance; 1058 } 1059 1060 // Creates the initial Thread 1061 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1062 TRAPS) { 1063 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1064 assert(ik->is_initialized(), "must be"); 1065 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1066 1067 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1068 // constructor calls Thread.current(), which must be set here for the 1069 // initial thread. 1070 java_lang_Thread::set_thread(thread_oop(), thread); 1071 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1072 thread->set_threadObj(thread_oop()); 1073 1074 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1075 1076 JavaValue result(T_VOID); 1077 JavaCalls::call_special(&result, thread_oop, 1078 ik, 1079 vmSymbols::object_initializer_name(), 1080 vmSymbols::threadgroup_string_void_signature(), 1081 thread_group, 1082 string, 1083 CHECK_NULL); 1084 return thread_oop(); 1085 } 1086 1087 char java_runtime_name[128] = ""; 1088 char java_runtime_version[128] = ""; 1089 1090 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1091 static const char* get_java_runtime_name(TRAPS) { 1092 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1093 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1094 fieldDescriptor fd; 1095 bool found = k != NULL && 1096 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1097 vmSymbols::string_signature(), &fd); 1098 if (found) { 1099 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1100 if (name_oop == NULL) { 1101 return NULL; 1102 } 1103 const char* name = java_lang_String::as_utf8_string(name_oop, 1104 java_runtime_name, 1105 sizeof(java_runtime_name)); 1106 return name; 1107 } else { 1108 return NULL; 1109 } 1110 } 1111 1112 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1113 static const char* get_java_runtime_version(TRAPS) { 1114 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1115 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1116 fieldDescriptor fd; 1117 bool found = k != NULL && 1118 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1119 vmSymbols::string_signature(), &fd); 1120 if (found) { 1121 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1122 if (name_oop == NULL) { 1123 return NULL; 1124 } 1125 const char* name = java_lang_String::as_utf8_string(name_oop, 1126 java_runtime_version, 1127 sizeof(java_runtime_version)); 1128 return name; 1129 } else { 1130 return NULL; 1131 } 1132 } 1133 1134 // General purpose hook into Java code, run once when the VM is initialized. 1135 // The Java library method itself may be changed independently from the VM. 1136 static void call_postVMInitHook(TRAPS) { 1137 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1138 if (klass != NULL) { 1139 JavaValue result(T_VOID); 1140 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1141 vmSymbols::void_method_signature(), 1142 CHECK); 1143 } 1144 } 1145 1146 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1147 bool daemon, TRAPS) { 1148 assert(thread_group.not_null(), "thread group should be specified"); 1149 assert(threadObj() == NULL, "should only create Java thread object once"); 1150 1151 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1152 assert(ik->is_initialized(), "must be"); 1153 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1154 1155 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1156 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1157 // constructor calls Thread.current(), which must be set here. 1158 java_lang_Thread::set_thread(thread_oop(), this); 1159 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1160 set_threadObj(thread_oop()); 1161 1162 JavaValue result(T_VOID); 1163 if (thread_name != NULL) { 1164 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1165 // Thread gets assigned specified name and null target 1166 JavaCalls::call_special(&result, 1167 thread_oop, 1168 ik, 1169 vmSymbols::object_initializer_name(), 1170 vmSymbols::threadgroup_string_void_signature(), 1171 thread_group, 1172 name, 1173 THREAD); 1174 } else { 1175 // Thread gets assigned name "Thread-nnn" and null target 1176 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1177 JavaCalls::call_special(&result, 1178 thread_oop, 1179 ik, 1180 vmSymbols::object_initializer_name(), 1181 vmSymbols::threadgroup_runnable_void_signature(), 1182 thread_group, 1183 Handle(), 1184 THREAD); 1185 } 1186 1187 1188 if (daemon) { 1189 java_lang_Thread::set_daemon(thread_oop()); 1190 } 1191 1192 if (HAS_PENDING_EXCEPTION) { 1193 return; 1194 } 1195 1196 Klass* group = SystemDictionary::ThreadGroup_klass(); 1197 Handle threadObj(THREAD, this->threadObj()); 1198 1199 JavaCalls::call_special(&result, 1200 thread_group, 1201 group, 1202 vmSymbols::add_method_name(), 1203 vmSymbols::thread_void_signature(), 1204 threadObj, // Arg 1 1205 THREAD); 1206 } 1207 1208 // NamedThread -- non-JavaThread subclasses with multiple 1209 // uniquely named instances should derive from this. 1210 NamedThread::NamedThread() : Thread() { 1211 _name = NULL; 1212 _processed_thread = NULL; 1213 _gc_id = GCId::undefined(); 1214 } 1215 1216 NamedThread::~NamedThread() { 1217 if (_name != NULL) { 1218 FREE_C_HEAP_ARRAY(char, _name); 1219 _name = NULL; 1220 } 1221 } 1222 1223 void NamedThread::set_name(const char* format, ...) { 1224 guarantee(_name == NULL, "Only get to set name once."); 1225 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1226 guarantee(_name != NULL, "alloc failure"); 1227 va_list ap; 1228 va_start(ap, format); 1229 jio_vsnprintf(_name, max_name_len, format, ap); 1230 va_end(ap); 1231 } 1232 1233 void NamedThread::initialize_named_thread() { 1234 set_native_thread_name(name()); 1235 } 1236 1237 void NamedThread::print_on(outputStream* st) const { 1238 st->print("\"%s\" ", name()); 1239 Thread::print_on(st); 1240 st->cr(); 1241 } 1242 1243 1244 // ======= WatcherThread ======== 1245 1246 // The watcher thread exists to simulate timer interrupts. It should 1247 // be replaced by an abstraction over whatever native support for 1248 // timer interrupts exists on the platform. 1249 1250 WatcherThread* WatcherThread::_watcher_thread = NULL; 1251 bool WatcherThread::_startable = false; 1252 volatile bool WatcherThread::_should_terminate = false; 1253 1254 WatcherThread::WatcherThread() : Thread() { 1255 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1256 if (os::create_thread(this, os::watcher_thread)) { 1257 _watcher_thread = this; 1258 1259 // Set the watcher thread to the highest OS priority which should not be 1260 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1261 // is created. The only normal thread using this priority is the reference 1262 // handler thread, which runs for very short intervals only. 1263 // If the VMThread's priority is not lower than the WatcherThread profiling 1264 // will be inaccurate. 1265 os::set_priority(this, MaxPriority); 1266 if (!DisableStartThread) { 1267 os::start_thread(this); 1268 } 1269 } 1270 } 1271 1272 int WatcherThread::sleep() const { 1273 // The WatcherThread does not participate in the safepoint protocol 1274 // for the PeriodicTask_lock because it is not a JavaThread. 1275 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1276 1277 if (_should_terminate) { 1278 // check for termination before we do any housekeeping or wait 1279 return 0; // we did not sleep. 1280 } 1281 1282 // remaining will be zero if there are no tasks, 1283 // causing the WatcherThread to sleep until a task is 1284 // enrolled 1285 int remaining = PeriodicTask::time_to_wait(); 1286 int time_slept = 0; 1287 1288 // we expect this to timeout - we only ever get unparked when 1289 // we should terminate or when a new task has been enrolled 1290 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1291 1292 jlong time_before_loop = os::javaTimeNanos(); 1293 1294 while (true) { 1295 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1296 remaining); 1297 jlong now = os::javaTimeNanos(); 1298 1299 if (remaining == 0) { 1300 // if we didn't have any tasks we could have waited for a long time 1301 // consider the time_slept zero and reset time_before_loop 1302 time_slept = 0; 1303 time_before_loop = now; 1304 } else { 1305 // need to recalculate since we might have new tasks in _tasks 1306 time_slept = (int) ((now - time_before_loop) / 1000000); 1307 } 1308 1309 // Change to task list or spurious wakeup of some kind 1310 if (timedout || _should_terminate) { 1311 break; 1312 } 1313 1314 remaining = PeriodicTask::time_to_wait(); 1315 if (remaining == 0) { 1316 // Last task was just disenrolled so loop around and wait until 1317 // another task gets enrolled 1318 continue; 1319 } 1320 1321 remaining -= time_slept; 1322 if (remaining <= 0) { 1323 break; 1324 } 1325 } 1326 1327 return time_slept; 1328 } 1329 1330 void WatcherThread::run() { 1331 assert(this == watcher_thread(), "just checking"); 1332 1333 this->record_stack_base_and_size(); 1334 this->set_native_thread_name(this->name()); 1335 this->set_active_handles(JNIHandleBlock::allocate_block()); 1336 while (true) { 1337 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1338 assert(watcher_thread() == this, "thread consistency check"); 1339 1340 // Calculate how long it'll be until the next PeriodicTask work 1341 // should be done, and sleep that amount of time. 1342 int time_waited = sleep(); 1343 1344 if (VMError::is_error_reported()) { 1345 // A fatal error has happened, the error handler(VMError::report_and_die) 1346 // should abort JVM after creating an error log file. However in some 1347 // rare cases, the error handler itself might deadlock. Here periodically 1348 // check for error reporting timeouts, and if it happens, just proceed to 1349 // abort the VM. 1350 1351 // This code is in WatcherThread because WatcherThread wakes up 1352 // periodically so the fatal error handler doesn't need to do anything; 1353 // also because the WatcherThread is less likely to crash than other 1354 // threads. 1355 1356 for (;;) { 1357 // Note: we use naked sleep in this loop because we want to avoid using 1358 // any kind of VM infrastructure which may be broken at this point. 1359 if (VMError::check_timeout()) { 1360 // We hit error reporting timeout. Error reporting was interrupted and 1361 // will be wrapping things up now (closing files etc). Give it some more 1362 // time, then quit the VM. 1363 os::naked_short_sleep(200); 1364 // Print a message to stderr. 1365 fdStream err(defaultStream::output_fd()); 1366 err.print_raw_cr("# [ timer expired, abort... ]"); 1367 // skip atexit/vm_exit/vm_abort hooks 1368 os::die(); 1369 } 1370 1371 // Wait a second, then recheck for timeout. 1372 os::naked_short_sleep(999); 1373 } 1374 } 1375 1376 if (_should_terminate) { 1377 // check for termination before posting the next tick 1378 break; 1379 } 1380 1381 PeriodicTask::real_time_tick(time_waited); 1382 } 1383 1384 // Signal that it is terminated 1385 { 1386 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1387 _watcher_thread = NULL; 1388 Terminator_lock->notify(); 1389 } 1390 } 1391 1392 void WatcherThread::start() { 1393 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1394 1395 if (watcher_thread() == NULL && _startable) { 1396 _should_terminate = false; 1397 // Create the single instance of WatcherThread 1398 new WatcherThread(); 1399 } 1400 } 1401 1402 void WatcherThread::make_startable() { 1403 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1404 _startable = true; 1405 } 1406 1407 void WatcherThread::stop() { 1408 { 1409 // Follow normal safepoint aware lock enter protocol since the 1410 // WatcherThread is stopped by another JavaThread. 1411 MutexLocker ml(PeriodicTask_lock); 1412 _should_terminate = true; 1413 1414 WatcherThread* watcher = watcher_thread(); 1415 if (watcher != NULL) { 1416 // unpark the WatcherThread so it can see that it should terminate 1417 watcher->unpark(); 1418 } 1419 } 1420 1421 MutexLocker mu(Terminator_lock); 1422 1423 while (watcher_thread() != NULL) { 1424 // This wait should make safepoint checks, wait without a timeout, 1425 // and wait as a suspend-equivalent condition. 1426 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1427 Mutex::_as_suspend_equivalent_flag); 1428 } 1429 } 1430 1431 void WatcherThread::unpark() { 1432 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1433 PeriodicTask_lock->notify(); 1434 } 1435 1436 void WatcherThread::print_on(outputStream* st) const { 1437 st->print("\"%s\" ", name()); 1438 Thread::print_on(st); 1439 st->cr(); 1440 } 1441 1442 // ======= JavaThread ======== 1443 1444 #if INCLUDE_JVMCI 1445 1446 jlong* JavaThread::_jvmci_old_thread_counters; 1447 1448 bool jvmci_counters_include(JavaThread* thread) { 1449 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1450 } 1451 1452 void JavaThread::collect_counters(typeArrayOop array) { 1453 if (JVMCICounterSize > 0) { 1454 JavaThreadIteratorWithHandle jtiwh; 1455 for (int i = 0; i < array->length(); i++) { 1456 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1457 } 1458 for (; JavaThread *tp = jtiwh.next(); ) { 1459 if (jvmci_counters_include(tp)) { 1460 for (int i = 0; i < array->length(); i++) { 1461 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1462 } 1463 } 1464 } 1465 } 1466 } 1467 1468 #endif // INCLUDE_JVMCI 1469 1470 // A JavaThread is a normal Java thread 1471 1472 void JavaThread::initialize() { 1473 // Initialize fields 1474 1475 set_saved_exception_pc(NULL); 1476 set_threadObj(NULL); 1477 _anchor.clear(); 1478 set_entry_point(NULL); 1479 set_jni_functions(jni_functions()); 1480 set_callee_target(NULL); 1481 set_vm_result(NULL); 1482 set_vm_result_2(NULL); 1483 set_vframe_array_head(NULL); 1484 set_vframe_array_last(NULL); 1485 set_deferred_locals(NULL); 1486 set_deopt_mark(NULL); 1487 set_deopt_compiled_method(NULL); 1488 clear_must_deopt_id(); 1489 set_monitor_chunks(NULL); 1490 set_next(NULL); 1491 _on_thread_list = false; 1492 set_thread_state(_thread_new); 1493 _terminated = _not_terminated; 1494 _privileged_stack_top = NULL; 1495 _array_for_gc = NULL; 1496 _suspend_equivalent = false; 1497 _in_deopt_handler = 0; 1498 _doing_unsafe_access = false; 1499 _stack_guard_state = stack_guard_unused; 1500 #if INCLUDE_JVMCI 1501 _pending_monitorenter = false; 1502 _pending_deoptimization = -1; 1503 _pending_failed_speculation = 0; 1504 _pending_transfer_to_interpreter = false; 1505 _adjusting_comp_level = false; 1506 _jvmci._alternate_call_target = NULL; 1507 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1508 if (JVMCICounterSize > 0) { 1509 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1510 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1511 } else { 1512 _jvmci_counters = NULL; 1513 } 1514 #endif // INCLUDE_JVMCI 1515 _reserved_stack_activation = NULL; // stack base not known yet 1516 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1517 _exception_pc = 0; 1518 _exception_handler_pc = 0; 1519 _is_method_handle_return = 0; 1520 _jvmti_thread_state= NULL; 1521 _should_post_on_exceptions_flag = JNI_FALSE; 1522 _jvmti_get_loaded_classes_closure = NULL; 1523 _interp_only_mode = 0; 1524 _special_runtime_exit_condition = _no_async_condition; 1525 _pending_async_exception = NULL; 1526 _thread_stat = NULL; 1527 _thread_stat = new ThreadStatistics(); 1528 _blocked_on_compilation = false; 1529 _jni_active_critical = 0; 1530 _pending_jni_exception_check_fn = NULL; 1531 _do_not_unlock_if_synchronized = false; 1532 _cached_monitor_info = NULL; 1533 _parker = Parker::Allocate(this); 1534 1535 #ifndef PRODUCT 1536 _jmp_ring_index = 0; 1537 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1538 record_jump(NULL, NULL, NULL, 0); 1539 } 1540 #endif // PRODUCT 1541 1542 // Setup safepoint state info for this thread 1543 ThreadSafepointState::create(this); 1544 1545 debug_only(_java_call_counter = 0); 1546 1547 // JVMTI PopFrame support 1548 _popframe_condition = popframe_inactive; 1549 _popframe_preserved_args = NULL; 1550 _popframe_preserved_args_size = 0; 1551 _frames_to_pop_failed_realloc = 0; 1552 1553 if (SafepointMechanism::uses_thread_local_poll()) { 1554 SafepointMechanism::initialize_header(this); 1555 } 1556 1557 pd_initialize(); 1558 } 1559 1560 JavaThread::JavaThread(bool is_attaching_via_jni) : 1561 Thread() { 1562 initialize(); 1563 if (is_attaching_via_jni) { 1564 _jni_attach_state = _attaching_via_jni; 1565 } else { 1566 _jni_attach_state = _not_attaching_via_jni; 1567 } 1568 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1569 } 1570 1571 bool JavaThread::reguard_stack(address cur_sp) { 1572 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1573 && _stack_guard_state != stack_guard_reserved_disabled) { 1574 return true; // Stack already guarded or guard pages not needed. 1575 } 1576 1577 if (register_stack_overflow()) { 1578 // For those architectures which have separate register and 1579 // memory stacks, we must check the register stack to see if 1580 // it has overflowed. 1581 return false; 1582 } 1583 1584 // Java code never executes within the yellow zone: the latter is only 1585 // there to provoke an exception during stack banging. If java code 1586 // is executing there, either StackShadowPages should be larger, or 1587 // some exception code in c1, c2 or the interpreter isn't unwinding 1588 // when it should. 1589 guarantee(cur_sp > stack_reserved_zone_base(), 1590 "not enough space to reguard - increase StackShadowPages"); 1591 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1592 enable_stack_yellow_reserved_zone(); 1593 if (reserved_stack_activation() != stack_base()) { 1594 set_reserved_stack_activation(stack_base()); 1595 } 1596 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1597 set_reserved_stack_activation(stack_base()); 1598 enable_stack_reserved_zone(); 1599 } 1600 return true; 1601 } 1602 1603 bool JavaThread::reguard_stack(void) { 1604 return reguard_stack(os::current_stack_pointer()); 1605 } 1606 1607 1608 void JavaThread::block_if_vm_exited() { 1609 if (_terminated == _vm_exited) { 1610 // _vm_exited is set at safepoint, and Threads_lock is never released 1611 // we will block here forever 1612 Threads_lock->lock_without_safepoint_check(); 1613 ShouldNotReachHere(); 1614 } 1615 } 1616 1617 1618 // Remove this ifdef when C1 is ported to the compiler interface. 1619 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1620 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1621 1622 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1623 Thread() { 1624 initialize(); 1625 _jni_attach_state = _not_attaching_via_jni; 1626 set_entry_point(entry_point); 1627 // Create the native thread itself. 1628 // %note runtime_23 1629 os::ThreadType thr_type = os::java_thread; 1630 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1631 os::java_thread; 1632 os::create_thread(this, thr_type, stack_sz); 1633 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1634 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1635 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1636 // the exception consists of creating the exception object & initializing it, initialization 1637 // will leave the VM via a JavaCall and then all locks must be unlocked). 1638 // 1639 // The thread is still suspended when we reach here. Thread must be explicit started 1640 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1641 // by calling Threads:add. The reason why this is not done here, is because the thread 1642 // object must be fully initialized (take a look at JVM_Start) 1643 } 1644 1645 JavaThread::~JavaThread() { 1646 1647 // JSR166 -- return the parker to the free list 1648 Parker::Release(_parker); 1649 _parker = NULL; 1650 1651 // Free any remaining previous UnrollBlock 1652 vframeArray* old_array = vframe_array_last(); 1653 1654 if (old_array != NULL) { 1655 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1656 old_array->set_unroll_block(NULL); 1657 delete old_info; 1658 delete old_array; 1659 } 1660 1661 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1662 if (deferred != NULL) { 1663 // This can only happen if thread is destroyed before deoptimization occurs. 1664 assert(deferred->length() != 0, "empty array!"); 1665 do { 1666 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1667 deferred->remove_at(0); 1668 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1669 delete dlv; 1670 } while (deferred->length() != 0); 1671 delete deferred; 1672 } 1673 1674 // All Java related clean up happens in exit 1675 ThreadSafepointState::destroy(this); 1676 if (_thread_stat != NULL) delete _thread_stat; 1677 1678 #if INCLUDE_JVMCI 1679 if (JVMCICounterSize > 0) { 1680 if (jvmci_counters_include(this)) { 1681 for (int i = 0; i < JVMCICounterSize; i++) { 1682 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1683 } 1684 } 1685 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1686 } 1687 #endif // INCLUDE_JVMCI 1688 } 1689 1690 1691 // The first routine called by a new Java thread 1692 void JavaThread::run() { 1693 // initialize thread-local alloc buffer related fields 1694 this->initialize_tlab(); 1695 1696 // used to test validity of stack trace backs 1697 this->record_base_of_stack_pointer(); 1698 1699 // Record real stack base and size. 1700 this->record_stack_base_and_size(); 1701 1702 this->create_stack_guard_pages(); 1703 1704 this->cache_global_variables(); 1705 1706 // Thread is now sufficient initialized to be handled by the safepoint code as being 1707 // in the VM. Change thread state from _thread_new to _thread_in_vm 1708 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1709 1710 assert(JavaThread::current() == this, "sanity check"); 1711 assert(!Thread::current()->owns_locks(), "sanity check"); 1712 1713 DTRACE_THREAD_PROBE(start, this); 1714 1715 // This operation might block. We call that after all safepoint checks for a new thread has 1716 // been completed. 1717 this->set_active_handles(JNIHandleBlock::allocate_block()); 1718 1719 if (JvmtiExport::should_post_thread_life()) { 1720 JvmtiExport::post_thread_start(this); 1721 } 1722 1723 EventThreadStart event; 1724 if (event.should_commit()) { 1725 event.set_thread(JFR_THREAD_ID(this)); 1726 event.commit(); 1727 } 1728 1729 // We call another function to do the rest so we are sure that the stack addresses used 1730 // from there will be lower than the stack base just computed 1731 thread_main_inner(); 1732 1733 // Note, thread is no longer valid at this point! 1734 } 1735 1736 1737 void JavaThread::thread_main_inner() { 1738 assert(JavaThread::current() == this, "sanity check"); 1739 assert(this->threadObj() != NULL, "just checking"); 1740 1741 // Execute thread entry point unless this thread has a pending exception 1742 // or has been stopped before starting. 1743 // Note: Due to JVM_StopThread we can have pending exceptions already! 1744 if (!this->has_pending_exception() && 1745 !java_lang_Thread::is_stillborn(this->threadObj())) { 1746 { 1747 ResourceMark rm(this); 1748 this->set_native_thread_name(this->get_thread_name()); 1749 } 1750 HandleMark hm(this); 1751 this->entry_point()(this, this); 1752 } 1753 1754 DTRACE_THREAD_PROBE(stop, this); 1755 1756 this->exit(false); 1757 this->smr_delete(); 1758 } 1759 1760 1761 static void ensure_join(JavaThread* thread) { 1762 // We do not need to grab the Threads_lock, since we are operating on ourself. 1763 Handle threadObj(thread, thread->threadObj()); 1764 assert(threadObj.not_null(), "java thread object must exist"); 1765 ObjectLocker lock(threadObj, thread); 1766 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1767 thread->clear_pending_exception(); 1768 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1769 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1770 // Clear the native thread instance - this makes isAlive return false and allows the join() 1771 // to complete once we've done the notify_all below 1772 java_lang_Thread::set_thread(threadObj(), NULL); 1773 lock.notify_all(thread); 1774 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1775 thread->clear_pending_exception(); 1776 } 1777 1778 1779 // For any new cleanup additions, please check to see if they need to be applied to 1780 // cleanup_failed_attach_current_thread as well. 1781 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1782 assert(this == JavaThread::current(), "thread consistency check"); 1783 1784 elapsedTimer _timer_exit_phase1; 1785 elapsedTimer _timer_exit_phase2; 1786 elapsedTimer _timer_exit_phase3; 1787 elapsedTimer _timer_exit_phase4; 1788 1789 if (log_is_enabled(Debug, os, thread, timer)) { 1790 _timer_exit_phase1.start(); 1791 } 1792 1793 HandleMark hm(this); 1794 Handle uncaught_exception(this, this->pending_exception()); 1795 this->clear_pending_exception(); 1796 Handle threadObj(this, this->threadObj()); 1797 assert(threadObj.not_null(), "Java thread object should be created"); 1798 1799 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1800 { 1801 EXCEPTION_MARK; 1802 1803 CLEAR_PENDING_EXCEPTION; 1804 } 1805 if (!destroy_vm) { 1806 if (uncaught_exception.not_null()) { 1807 EXCEPTION_MARK; 1808 // Call method Thread.dispatchUncaughtException(). 1809 Klass* thread_klass = SystemDictionary::Thread_klass(); 1810 JavaValue result(T_VOID); 1811 JavaCalls::call_virtual(&result, 1812 threadObj, thread_klass, 1813 vmSymbols::dispatchUncaughtException_name(), 1814 vmSymbols::throwable_void_signature(), 1815 uncaught_exception, 1816 THREAD); 1817 if (HAS_PENDING_EXCEPTION) { 1818 ResourceMark rm(this); 1819 jio_fprintf(defaultStream::error_stream(), 1820 "\nException: %s thrown from the UncaughtExceptionHandler" 1821 " in thread \"%s\"\n", 1822 pending_exception()->klass()->external_name(), 1823 get_thread_name()); 1824 CLEAR_PENDING_EXCEPTION; 1825 } 1826 } 1827 1828 // Called before the java thread exit since we want to read info 1829 // from java_lang_Thread object 1830 EventThreadEnd event; 1831 if (event.should_commit()) { 1832 event.set_thread(JFR_THREAD_ID(this)); 1833 event.commit(); 1834 } 1835 1836 // Call after last event on thread 1837 JFR_ONLY(Jfr::on_thread_exit(this);) 1838 1839 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1840 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1841 // is deprecated anyhow. 1842 if (!is_Compiler_thread()) { 1843 int count = 3; 1844 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1845 EXCEPTION_MARK; 1846 JavaValue result(T_VOID); 1847 Klass* thread_klass = SystemDictionary::Thread_klass(); 1848 JavaCalls::call_virtual(&result, 1849 threadObj, thread_klass, 1850 vmSymbols::exit_method_name(), 1851 vmSymbols::void_method_signature(), 1852 THREAD); 1853 CLEAR_PENDING_EXCEPTION; 1854 } 1855 } 1856 // notify JVMTI 1857 if (JvmtiExport::should_post_thread_life()) { 1858 JvmtiExport::post_thread_end(this); 1859 } 1860 1861 // We have notified the agents that we are exiting, before we go on, 1862 // we must check for a pending external suspend request and honor it 1863 // in order to not surprise the thread that made the suspend request. 1864 while (true) { 1865 { 1866 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1867 if (!is_external_suspend()) { 1868 set_terminated(_thread_exiting); 1869 ThreadService::current_thread_exiting(this); 1870 break; 1871 } 1872 // Implied else: 1873 // Things get a little tricky here. We have a pending external 1874 // suspend request, but we are holding the SR_lock so we 1875 // can't just self-suspend. So we temporarily drop the lock 1876 // and then self-suspend. 1877 } 1878 1879 ThreadBlockInVM tbivm(this); 1880 java_suspend_self(); 1881 1882 // We're done with this suspend request, but we have to loop around 1883 // and check again. Eventually we will get SR_lock without a pending 1884 // external suspend request and will be able to mark ourselves as 1885 // exiting. 1886 } 1887 // no more external suspends are allowed at this point 1888 } else { 1889 // before_exit() has already posted JVMTI THREAD_END events 1890 } 1891 1892 if (log_is_enabled(Debug, os, thread, timer)) { 1893 _timer_exit_phase1.stop(); 1894 _timer_exit_phase2.start(); 1895 } 1896 // Notify waiters on thread object. This has to be done after exit() is called 1897 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1898 // group should have the destroyed bit set before waiters are notified). 1899 ensure_join(this); 1900 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1901 1902 if (log_is_enabled(Debug, os, thread, timer)) { 1903 _timer_exit_phase2.stop(); 1904 _timer_exit_phase3.start(); 1905 } 1906 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1907 // held by this thread must be released. The spec does not distinguish 1908 // between JNI-acquired and regular Java monitors. We can only see 1909 // regular Java monitors here if monitor enter-exit matching is broken. 1910 // 1911 // Optionally release any monitors for regular JavaThread exits. This 1912 // is provided as a work around for any bugs in monitor enter-exit 1913 // matching. This can be expensive so it is not enabled by default. 1914 // 1915 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1916 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1917 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1918 // Sanity check even though JNI DetachCurrentThread() would have 1919 // returned JNI_ERR if there was a Java frame. JavaThread exit 1920 // should be done executing Java code by the time we get here. 1921 assert(!this->has_last_Java_frame(), 1922 "should not have a Java frame when detaching or exiting"); 1923 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1924 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1925 } 1926 1927 // These things needs to be done while we are still a Java Thread. Make sure that thread 1928 // is in a consistent state, in case GC happens 1929 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1930 1931 if (active_handles() != NULL) { 1932 JNIHandleBlock* block = active_handles(); 1933 set_active_handles(NULL); 1934 JNIHandleBlock::release_block(block); 1935 } 1936 1937 if (free_handle_block() != NULL) { 1938 JNIHandleBlock* block = free_handle_block(); 1939 set_free_handle_block(NULL); 1940 JNIHandleBlock::release_block(block); 1941 } 1942 1943 // These have to be removed while this is still a valid thread. 1944 remove_stack_guard_pages(); 1945 1946 if (UseTLAB) { 1947 tlab().make_parsable(true); // retire TLAB 1948 } 1949 1950 if (JvmtiEnv::environments_might_exist()) { 1951 JvmtiExport::cleanup_thread(this); 1952 } 1953 1954 // We must flush any deferred card marks and other various GC barrier 1955 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 1956 // before removing a thread from the list of active threads. 1957 BarrierSet::barrier_set()->on_thread_detach(this); 1958 1959 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1960 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1961 os::current_thread_id()); 1962 1963 if (log_is_enabled(Debug, os, thread, timer)) { 1964 _timer_exit_phase3.stop(); 1965 _timer_exit_phase4.start(); 1966 } 1967 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1968 Threads::remove(this); 1969 1970 if (log_is_enabled(Debug, os, thread, timer)) { 1971 _timer_exit_phase4.stop(); 1972 ResourceMark rm(this); 1973 log_debug(os, thread, timer)("name='%s'" 1974 ", exit-phase1=" JLONG_FORMAT 1975 ", exit-phase2=" JLONG_FORMAT 1976 ", exit-phase3=" JLONG_FORMAT 1977 ", exit-phase4=" JLONG_FORMAT, 1978 get_thread_name(), 1979 _timer_exit_phase1.milliseconds(), 1980 _timer_exit_phase2.milliseconds(), 1981 _timer_exit_phase3.milliseconds(), 1982 _timer_exit_phase4.milliseconds()); 1983 } 1984 } 1985 1986 void JavaThread::cleanup_failed_attach_current_thread() { 1987 if (active_handles() != NULL) { 1988 JNIHandleBlock* block = active_handles(); 1989 set_active_handles(NULL); 1990 JNIHandleBlock::release_block(block); 1991 } 1992 1993 if (free_handle_block() != NULL) { 1994 JNIHandleBlock* block = free_handle_block(); 1995 set_free_handle_block(NULL); 1996 JNIHandleBlock::release_block(block); 1997 } 1998 1999 // These have to be removed while this is still a valid thread. 2000 remove_stack_guard_pages(); 2001 2002 if (UseTLAB) { 2003 tlab().make_parsable(true); // retire TLAB, if any 2004 } 2005 2006 BarrierSet::barrier_set()->on_thread_detach(this); 2007 2008 Threads::remove(this); 2009 this->smr_delete(); 2010 } 2011 2012 JavaThread* JavaThread::active() { 2013 Thread* thread = Thread::current(); 2014 if (thread->is_Java_thread()) { 2015 return (JavaThread*) thread; 2016 } else { 2017 assert(thread->is_VM_thread(), "this must be a vm thread"); 2018 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2019 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2020 assert(ret->is_Java_thread(), "must be a Java thread"); 2021 return ret; 2022 } 2023 } 2024 2025 bool JavaThread::is_lock_owned(address adr) const { 2026 if (Thread::is_lock_owned(adr)) return true; 2027 2028 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2029 if (chunk->contains(adr)) return true; 2030 } 2031 2032 return false; 2033 } 2034 2035 2036 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2037 chunk->set_next(monitor_chunks()); 2038 set_monitor_chunks(chunk); 2039 } 2040 2041 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2042 guarantee(monitor_chunks() != NULL, "must be non empty"); 2043 if (monitor_chunks() == chunk) { 2044 set_monitor_chunks(chunk->next()); 2045 } else { 2046 MonitorChunk* prev = monitor_chunks(); 2047 while (prev->next() != chunk) prev = prev->next(); 2048 prev->set_next(chunk->next()); 2049 } 2050 } 2051 2052 // JVM support. 2053 2054 // Note: this function shouldn't block if it's called in 2055 // _thread_in_native_trans state (such as from 2056 // check_special_condition_for_native_trans()). 2057 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2058 2059 if (has_last_Java_frame() && has_async_condition()) { 2060 // If we are at a polling page safepoint (not a poll return) 2061 // then we must defer async exception because live registers 2062 // will be clobbered by the exception path. Poll return is 2063 // ok because the call we a returning from already collides 2064 // with exception handling registers and so there is no issue. 2065 // (The exception handling path kills call result registers but 2066 // this is ok since the exception kills the result anyway). 2067 2068 if (is_at_poll_safepoint()) { 2069 // if the code we are returning to has deoptimized we must defer 2070 // the exception otherwise live registers get clobbered on the 2071 // exception path before deoptimization is able to retrieve them. 2072 // 2073 RegisterMap map(this, false); 2074 frame caller_fr = last_frame().sender(&map); 2075 assert(caller_fr.is_compiled_frame(), "what?"); 2076 if (caller_fr.is_deoptimized_frame()) { 2077 log_info(exceptions)("deferred async exception at compiled safepoint"); 2078 return; 2079 } 2080 } 2081 } 2082 2083 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2084 if (condition == _no_async_condition) { 2085 // Conditions have changed since has_special_runtime_exit_condition() 2086 // was called: 2087 // - if we were here only because of an external suspend request, 2088 // then that was taken care of above (or cancelled) so we are done 2089 // - if we were here because of another async request, then it has 2090 // been cleared between the has_special_runtime_exit_condition() 2091 // and now so again we are done 2092 return; 2093 } 2094 2095 // Check for pending async. exception 2096 if (_pending_async_exception != NULL) { 2097 // Only overwrite an already pending exception, if it is not a threadDeath. 2098 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2099 2100 // We cannot call Exceptions::_throw(...) here because we cannot block 2101 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2102 2103 LogTarget(Info, exceptions) lt; 2104 if (lt.is_enabled()) { 2105 ResourceMark rm; 2106 LogStream ls(lt); 2107 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2108 if (has_last_Java_frame()) { 2109 frame f = last_frame(); 2110 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2111 } 2112 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2113 } 2114 _pending_async_exception = NULL; 2115 clear_has_async_exception(); 2116 } 2117 } 2118 2119 if (check_unsafe_error && 2120 condition == _async_unsafe_access_error && !has_pending_exception()) { 2121 condition = _no_async_condition; // done 2122 switch (thread_state()) { 2123 case _thread_in_vm: { 2124 JavaThread* THREAD = this; 2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2126 } 2127 case _thread_in_native: { 2128 ThreadInVMfromNative tiv(this); 2129 JavaThread* THREAD = this; 2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2131 } 2132 case _thread_in_Java: { 2133 ThreadInVMfromJava tiv(this); 2134 JavaThread* THREAD = this; 2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2136 } 2137 default: 2138 ShouldNotReachHere(); 2139 } 2140 } 2141 2142 assert(condition == _no_async_condition || has_pending_exception() || 2143 (!check_unsafe_error && condition == _async_unsafe_access_error), 2144 "must have handled the async condition, if no exception"); 2145 } 2146 2147 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2148 // 2149 // Check for pending external suspend. Internal suspend requests do 2150 // not use handle_special_runtime_exit_condition(). 2151 // If JNIEnv proxies are allowed, don't self-suspend if the target 2152 // thread is not the current thread. In older versions of jdbx, jdbx 2153 // threads could call into the VM with another thread's JNIEnv so we 2154 // can be here operating on behalf of a suspended thread (4432884). 2155 bool do_self_suspend = is_external_suspend_with_lock(); 2156 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2157 // 2158 // Because thread is external suspended the safepoint code will count 2159 // thread as at a safepoint. This can be odd because we can be here 2160 // as _thread_in_Java which would normally transition to _thread_blocked 2161 // at a safepoint. We would like to mark the thread as _thread_blocked 2162 // before calling java_suspend_self like all other callers of it but 2163 // we must then observe proper safepoint protocol. (We can't leave 2164 // _thread_blocked with a safepoint in progress). However we can be 2165 // here as _thread_in_native_trans so we can't use a normal transition 2166 // constructor/destructor pair because they assert on that type of 2167 // transition. We could do something like: 2168 // 2169 // JavaThreadState state = thread_state(); 2170 // set_thread_state(_thread_in_vm); 2171 // { 2172 // ThreadBlockInVM tbivm(this); 2173 // java_suspend_self() 2174 // } 2175 // set_thread_state(_thread_in_vm_trans); 2176 // if (safepoint) block; 2177 // set_thread_state(state); 2178 // 2179 // but that is pretty messy. Instead we just go with the way the 2180 // code has worked before and note that this is the only path to 2181 // java_suspend_self that doesn't put the thread in _thread_blocked 2182 // mode. 2183 2184 frame_anchor()->make_walkable(this); 2185 java_suspend_self(); 2186 2187 // We might be here for reasons in addition to the self-suspend request 2188 // so check for other async requests. 2189 } 2190 2191 if (check_asyncs) { 2192 check_and_handle_async_exceptions(); 2193 } 2194 2195 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2196 } 2197 2198 void JavaThread::send_thread_stop(oop java_throwable) { 2199 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2200 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2201 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2202 2203 // Do not throw asynchronous exceptions against the compiler thread 2204 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2205 if (!can_call_java()) return; 2206 2207 { 2208 // Actually throw the Throwable against the target Thread - however 2209 // only if there is no thread death exception installed already. 2210 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2211 // If the topmost frame is a runtime stub, then we are calling into 2212 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2213 // must deoptimize the caller before continuing, as the compiled exception handler table 2214 // may not be valid 2215 if (has_last_Java_frame()) { 2216 frame f = last_frame(); 2217 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2218 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2219 RegisterMap reg_map(this, UseBiasedLocking); 2220 frame compiled_frame = f.sender(®_map); 2221 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2222 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2223 } 2224 } 2225 } 2226 2227 // Set async. pending exception in thread. 2228 set_pending_async_exception(java_throwable); 2229 2230 if (log_is_enabled(Info, exceptions)) { 2231 ResourceMark rm; 2232 log_info(exceptions)("Pending Async. exception installed of type: %s", 2233 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2234 } 2235 // for AbortVMOnException flag 2236 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2237 } 2238 } 2239 2240 2241 // Interrupt thread so it will wake up from a potential wait() 2242 Thread::interrupt(this); 2243 } 2244 2245 // External suspension mechanism. 2246 // 2247 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2248 // to any VM_locks and it is at a transition 2249 // Self-suspension will happen on the transition out of the vm. 2250 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2251 // 2252 // Guarantees on return: 2253 // + Target thread will not execute any new bytecode (that's why we need to 2254 // force a safepoint) 2255 // + Target thread will not enter any new monitors 2256 // 2257 void JavaThread::java_suspend() { 2258 ThreadsListHandle tlh; 2259 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2260 return; 2261 } 2262 2263 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2264 if (!is_external_suspend()) { 2265 // a racing resume has cancelled us; bail out now 2266 return; 2267 } 2268 2269 // suspend is done 2270 uint32_t debug_bits = 0; 2271 // Warning: is_ext_suspend_completed() may temporarily drop the 2272 // SR_lock to allow the thread to reach a stable thread state if 2273 // it is currently in a transient thread state. 2274 if (is_ext_suspend_completed(false /* !called_by_wait */, 2275 SuspendRetryDelay, &debug_bits)) { 2276 return; 2277 } 2278 } 2279 2280 VM_ThreadSuspend vm_suspend; 2281 VMThread::execute(&vm_suspend); 2282 } 2283 2284 // Part II of external suspension. 2285 // A JavaThread self suspends when it detects a pending external suspend 2286 // request. This is usually on transitions. It is also done in places 2287 // where continuing to the next transition would surprise the caller, 2288 // e.g., monitor entry. 2289 // 2290 // Returns the number of times that the thread self-suspended. 2291 // 2292 // Note: DO NOT call java_suspend_self() when you just want to block current 2293 // thread. java_suspend_self() is the second stage of cooperative 2294 // suspension for external suspend requests and should only be used 2295 // to complete an external suspend request. 2296 // 2297 int JavaThread::java_suspend_self() { 2298 int ret = 0; 2299 2300 // we are in the process of exiting so don't suspend 2301 if (is_exiting()) { 2302 clear_external_suspend(); 2303 return ret; 2304 } 2305 2306 assert(_anchor.walkable() || 2307 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2308 "must have walkable stack"); 2309 2310 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2311 2312 assert(!this->is_ext_suspended(), 2313 "a thread trying to self-suspend should not already be suspended"); 2314 2315 if (this->is_suspend_equivalent()) { 2316 // If we are self-suspending as a result of the lifting of a 2317 // suspend equivalent condition, then the suspend_equivalent 2318 // flag is not cleared until we set the ext_suspended flag so 2319 // that wait_for_ext_suspend_completion() returns consistent 2320 // results. 2321 this->clear_suspend_equivalent(); 2322 } 2323 2324 // A racing resume may have cancelled us before we grabbed SR_lock 2325 // above. Or another external suspend request could be waiting for us 2326 // by the time we return from SR_lock()->wait(). The thread 2327 // that requested the suspension may already be trying to walk our 2328 // stack and if we return now, we can change the stack out from under 2329 // it. This would be a "bad thing (TM)" and cause the stack walker 2330 // to crash. We stay self-suspended until there are no more pending 2331 // external suspend requests. 2332 while (is_external_suspend()) { 2333 ret++; 2334 this->set_ext_suspended(); 2335 2336 // _ext_suspended flag is cleared by java_resume() 2337 while (is_ext_suspended()) { 2338 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2339 } 2340 } 2341 2342 return ret; 2343 } 2344 2345 #ifdef ASSERT 2346 // Verify the JavaThread has not yet been published in the Threads::list, and 2347 // hence doesn't need protection from concurrent access at this stage. 2348 void JavaThread::verify_not_published() { 2349 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2350 // since an unpublished JavaThread doesn't participate in the 2351 // Thread-SMR protocol for keeping a ThreadsList alive. 2352 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2353 } 2354 #endif 2355 2356 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2357 // progress or when _suspend_flags is non-zero. 2358 // Current thread needs to self-suspend if there is a suspend request and/or 2359 // block if a safepoint is in progress. 2360 // Async exception ISN'T checked. 2361 // Note only the ThreadInVMfromNative transition can call this function 2362 // directly and when thread state is _thread_in_native_trans 2363 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2364 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2365 2366 JavaThread *curJT = JavaThread::current(); 2367 bool do_self_suspend = thread->is_external_suspend(); 2368 2369 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2370 2371 // If JNIEnv proxies are allowed, don't self-suspend if the target 2372 // thread is not the current thread. In older versions of jdbx, jdbx 2373 // threads could call into the VM with another thread's JNIEnv so we 2374 // can be here operating on behalf of a suspended thread (4432884). 2375 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2376 JavaThreadState state = thread->thread_state(); 2377 2378 // We mark this thread_blocked state as a suspend-equivalent so 2379 // that a caller to is_ext_suspend_completed() won't be confused. 2380 // The suspend-equivalent state is cleared by java_suspend_self(). 2381 thread->set_suspend_equivalent(); 2382 2383 // If the safepoint code sees the _thread_in_native_trans state, it will 2384 // wait until the thread changes to other thread state. There is no 2385 // guarantee on how soon we can obtain the SR_lock and complete the 2386 // self-suspend request. It would be a bad idea to let safepoint wait for 2387 // too long. Temporarily change the state to _thread_blocked to 2388 // let the VM thread know that this thread is ready for GC. The problem 2389 // of changing thread state is that safepoint could happen just after 2390 // java_suspend_self() returns after being resumed, and VM thread will 2391 // see the _thread_blocked state. We must check for safepoint 2392 // after restoring the state and make sure we won't leave while a safepoint 2393 // is in progress. 2394 thread->set_thread_state(_thread_blocked); 2395 thread->java_suspend_self(); 2396 thread->set_thread_state(state); 2397 2398 InterfaceSupport::serialize_thread_state_with_handler(thread); 2399 } 2400 2401 SafepointMechanism::block_if_requested(curJT); 2402 2403 if (thread->is_deopt_suspend()) { 2404 thread->clear_deopt_suspend(); 2405 RegisterMap map(thread, false); 2406 frame f = thread->last_frame(); 2407 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2408 f = f.sender(&map); 2409 } 2410 if (f.id() == thread->must_deopt_id()) { 2411 thread->clear_must_deopt_id(); 2412 f.deoptimize(thread); 2413 } else { 2414 fatal("missed deoptimization!"); 2415 } 2416 } 2417 2418 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2419 } 2420 2421 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2422 // progress or when _suspend_flags is non-zero. 2423 // Current thread needs to self-suspend if there is a suspend request and/or 2424 // block if a safepoint is in progress. 2425 // Also check for pending async exception (not including unsafe access error). 2426 // Note only the native==>VM/Java barriers can call this function and when 2427 // thread state is _thread_in_native_trans. 2428 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2429 check_safepoint_and_suspend_for_native_trans(thread); 2430 2431 if (thread->has_async_exception()) { 2432 // We are in _thread_in_native_trans state, don't handle unsafe 2433 // access error since that may block. 2434 thread->check_and_handle_async_exceptions(false); 2435 } 2436 } 2437 2438 // This is a variant of the normal 2439 // check_special_condition_for_native_trans with slightly different 2440 // semantics for use by critical native wrappers. It does all the 2441 // normal checks but also performs the transition back into 2442 // thread_in_Java state. This is required so that critical natives 2443 // can potentially block and perform a GC if they are the last thread 2444 // exiting the GCLocker. 2445 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2446 check_special_condition_for_native_trans(thread); 2447 2448 // Finish the transition 2449 thread->set_thread_state(_thread_in_Java); 2450 2451 if (thread->do_critical_native_unlock()) { 2452 ThreadInVMfromJavaNoAsyncException tiv(thread); 2453 GCLocker::unlock_critical(thread); 2454 thread->clear_critical_native_unlock(); 2455 } 2456 } 2457 2458 // We need to guarantee the Threads_lock here, since resumes are not 2459 // allowed during safepoint synchronization 2460 // Can only resume from an external suspension 2461 void JavaThread::java_resume() { 2462 assert_locked_or_safepoint(Threads_lock); 2463 2464 // Sanity check: thread is gone, has started exiting or the thread 2465 // was not externally suspended. 2466 ThreadsListHandle tlh; 2467 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2468 return; 2469 } 2470 2471 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2472 2473 clear_external_suspend(); 2474 2475 if (is_ext_suspended()) { 2476 clear_ext_suspended(); 2477 SR_lock()->notify_all(); 2478 } 2479 } 2480 2481 size_t JavaThread::_stack_red_zone_size = 0; 2482 size_t JavaThread::_stack_yellow_zone_size = 0; 2483 size_t JavaThread::_stack_reserved_zone_size = 0; 2484 size_t JavaThread::_stack_shadow_zone_size = 0; 2485 2486 void JavaThread::create_stack_guard_pages() { 2487 if (!os::uses_stack_guard_pages() || 2488 _stack_guard_state != stack_guard_unused || 2489 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2490 log_info(os, thread)("Stack guard page creation for thread " 2491 UINTX_FORMAT " disabled", os::current_thread_id()); 2492 return; 2493 } 2494 address low_addr = stack_end(); 2495 size_t len = stack_guard_zone_size(); 2496 2497 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2498 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2499 2500 int must_commit = os::must_commit_stack_guard_pages(); 2501 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2502 2503 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2504 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2505 return; 2506 } 2507 2508 if (os::guard_memory((char *) low_addr, len)) { 2509 _stack_guard_state = stack_guard_enabled; 2510 } else { 2511 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2512 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2513 if (os::uncommit_memory((char *) low_addr, len)) { 2514 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2515 } 2516 return; 2517 } 2518 2519 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2520 PTR_FORMAT "-" PTR_FORMAT ".", 2521 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2522 } 2523 2524 void JavaThread::remove_stack_guard_pages() { 2525 assert(Thread::current() == this, "from different thread"); 2526 if (_stack_guard_state == stack_guard_unused) return; 2527 address low_addr = stack_end(); 2528 size_t len = stack_guard_zone_size(); 2529 2530 if (os::must_commit_stack_guard_pages()) { 2531 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2532 _stack_guard_state = stack_guard_unused; 2533 } else { 2534 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2535 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2536 return; 2537 } 2538 } else { 2539 if (_stack_guard_state == stack_guard_unused) return; 2540 if (os::unguard_memory((char *) low_addr, len)) { 2541 _stack_guard_state = stack_guard_unused; 2542 } else { 2543 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2544 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2545 return; 2546 } 2547 } 2548 2549 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2550 PTR_FORMAT "-" PTR_FORMAT ".", 2551 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2552 } 2553 2554 void JavaThread::enable_stack_reserved_zone() { 2555 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2556 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2557 2558 // The base notation is from the stack's point of view, growing downward. 2559 // We need to adjust it to work correctly with guard_memory() 2560 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2561 2562 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2563 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2564 2565 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2566 _stack_guard_state = stack_guard_enabled; 2567 } else { 2568 warning("Attempt to guard stack reserved zone failed."); 2569 } 2570 enable_register_stack_guard(); 2571 } 2572 2573 void JavaThread::disable_stack_reserved_zone() { 2574 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2575 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2576 2577 // Simply return if called for a thread that does not use guard pages. 2578 if (_stack_guard_state == stack_guard_unused) return; 2579 2580 // The base notation is from the stack's point of view, growing downward. 2581 // We need to adjust it to work correctly with guard_memory() 2582 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2583 2584 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2585 _stack_guard_state = stack_guard_reserved_disabled; 2586 } else { 2587 warning("Attempt to unguard stack reserved zone failed."); 2588 } 2589 disable_register_stack_guard(); 2590 } 2591 2592 void JavaThread::enable_stack_yellow_reserved_zone() { 2593 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2594 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2595 2596 // The base notation is from the stacks point of view, growing downward. 2597 // We need to adjust it to work correctly with guard_memory() 2598 address base = stack_red_zone_base(); 2599 2600 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2601 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2602 2603 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2604 _stack_guard_state = stack_guard_enabled; 2605 } else { 2606 warning("Attempt to guard stack yellow zone failed."); 2607 } 2608 enable_register_stack_guard(); 2609 } 2610 2611 void JavaThread::disable_stack_yellow_reserved_zone() { 2612 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2613 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2614 2615 // Simply return if called for a thread that does not use guard pages. 2616 if (_stack_guard_state == stack_guard_unused) return; 2617 2618 // The base notation is from the stacks point of view, growing downward. 2619 // We need to adjust it to work correctly with guard_memory() 2620 address base = stack_red_zone_base(); 2621 2622 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2623 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2624 } else { 2625 warning("Attempt to unguard stack yellow zone failed."); 2626 } 2627 disable_register_stack_guard(); 2628 } 2629 2630 void JavaThread::enable_stack_red_zone() { 2631 // The base notation is from the stacks point of view, growing downward. 2632 // We need to adjust it to work correctly with guard_memory() 2633 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2634 address base = stack_red_zone_base() - stack_red_zone_size(); 2635 2636 guarantee(base < stack_base(), "Error calculating stack red zone"); 2637 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2638 2639 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2640 warning("Attempt to guard stack red zone failed."); 2641 } 2642 } 2643 2644 void JavaThread::disable_stack_red_zone() { 2645 // The base notation is from the stacks point of view, growing downward. 2646 // We need to adjust it to work correctly with guard_memory() 2647 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2648 address base = stack_red_zone_base() - stack_red_zone_size(); 2649 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2650 warning("Attempt to unguard stack red zone failed."); 2651 } 2652 } 2653 2654 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2655 // ignore is there is no stack 2656 if (!has_last_Java_frame()) return; 2657 // traverse the stack frames. Starts from top frame. 2658 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2659 frame* fr = fst.current(); 2660 f(fr, fst.register_map()); 2661 } 2662 } 2663 2664 2665 #ifndef PRODUCT 2666 // Deoptimization 2667 // Function for testing deoptimization 2668 void JavaThread::deoptimize() { 2669 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2670 StackFrameStream fst(this, UseBiasedLocking); 2671 bool deopt = false; // Dump stack only if a deopt actually happens. 2672 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2673 // Iterate over all frames in the thread and deoptimize 2674 for (; !fst.is_done(); fst.next()) { 2675 if (fst.current()->can_be_deoptimized()) { 2676 2677 if (only_at) { 2678 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2679 // consists of comma or carriage return separated numbers so 2680 // search for the current bci in that string. 2681 address pc = fst.current()->pc(); 2682 nmethod* nm = (nmethod*) fst.current()->cb(); 2683 ScopeDesc* sd = nm->scope_desc_at(pc); 2684 char buffer[8]; 2685 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2686 size_t len = strlen(buffer); 2687 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2688 while (found != NULL) { 2689 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2690 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2691 // Check that the bci found is bracketed by terminators. 2692 break; 2693 } 2694 found = strstr(found + 1, buffer); 2695 } 2696 if (!found) { 2697 continue; 2698 } 2699 } 2700 2701 if (DebugDeoptimization && !deopt) { 2702 deopt = true; // One-time only print before deopt 2703 tty->print_cr("[BEFORE Deoptimization]"); 2704 trace_frames(); 2705 trace_stack(); 2706 } 2707 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2708 } 2709 } 2710 2711 if (DebugDeoptimization && deopt) { 2712 tty->print_cr("[AFTER Deoptimization]"); 2713 trace_frames(); 2714 } 2715 } 2716 2717 2718 // Make zombies 2719 void JavaThread::make_zombies() { 2720 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2721 if (fst.current()->can_be_deoptimized()) { 2722 // it is a Java nmethod 2723 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2724 nm->make_not_entrant(); 2725 } 2726 } 2727 } 2728 #endif // PRODUCT 2729 2730 2731 void JavaThread::deoptimized_wrt_marked_nmethods() { 2732 if (!has_last_Java_frame()) return; 2733 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2734 StackFrameStream fst(this, UseBiasedLocking); 2735 for (; !fst.is_done(); fst.next()) { 2736 if (fst.current()->should_be_deoptimized()) { 2737 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2738 } 2739 } 2740 } 2741 2742 2743 // If the caller is a NamedThread, then remember, in the current scope, 2744 // the given JavaThread in its _processed_thread field. 2745 class RememberProcessedThread: public StackObj { 2746 NamedThread* _cur_thr; 2747 public: 2748 RememberProcessedThread(JavaThread* jthr) { 2749 Thread* thread = Thread::current(); 2750 if (thread->is_Named_thread()) { 2751 _cur_thr = (NamedThread *)thread; 2752 _cur_thr->set_processed_thread(jthr); 2753 } else { 2754 _cur_thr = NULL; 2755 } 2756 } 2757 2758 ~RememberProcessedThread() { 2759 if (_cur_thr) { 2760 _cur_thr->set_processed_thread(NULL); 2761 } 2762 } 2763 }; 2764 2765 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2766 // Verify that the deferred card marks have been flushed. 2767 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2768 2769 // Traverse the GCHandles 2770 Thread::oops_do(f, cf); 2771 2772 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2773 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2774 2775 if (has_last_Java_frame()) { 2776 // Record JavaThread to GC thread 2777 RememberProcessedThread rpt(this); 2778 2779 // Traverse the privileged stack 2780 if (_privileged_stack_top != NULL) { 2781 _privileged_stack_top->oops_do(f); 2782 } 2783 2784 // traverse the registered growable array 2785 if (_array_for_gc != NULL) { 2786 for (int index = 0; index < _array_for_gc->length(); index++) { 2787 f->do_oop(_array_for_gc->adr_at(index)); 2788 } 2789 } 2790 2791 // Traverse the monitor chunks 2792 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2793 chunk->oops_do(f); 2794 } 2795 2796 // Traverse the execution stack 2797 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2798 fst.current()->oops_do(f, cf, fst.register_map()); 2799 } 2800 } 2801 2802 // callee_target is never live across a gc point so NULL it here should 2803 // it still contain a methdOop. 2804 2805 set_callee_target(NULL); 2806 2807 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2808 // If we have deferred set_locals there might be oops waiting to be 2809 // written 2810 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2811 if (list != NULL) { 2812 for (int i = 0; i < list->length(); i++) { 2813 list->at(i)->oops_do(f); 2814 } 2815 } 2816 2817 // Traverse instance variables at the end since the GC may be moving things 2818 // around using this function 2819 f->do_oop((oop*) &_threadObj); 2820 f->do_oop((oop*) &_vm_result); 2821 f->do_oop((oop*) &_exception_oop); 2822 f->do_oop((oop*) &_pending_async_exception); 2823 2824 if (jvmti_thread_state() != NULL) { 2825 jvmti_thread_state()->oops_do(f); 2826 } 2827 } 2828 2829 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2830 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2831 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2832 2833 if (has_last_Java_frame()) { 2834 // Traverse the execution stack 2835 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2836 fst.current()->nmethods_do(cf); 2837 } 2838 } 2839 } 2840 2841 void JavaThread::metadata_do(void f(Metadata*)) { 2842 if (has_last_Java_frame()) { 2843 // Traverse the execution stack to call f() on the methods in the stack 2844 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2845 fst.current()->metadata_do(f); 2846 } 2847 } else if (is_Compiler_thread()) { 2848 // need to walk ciMetadata in current compile tasks to keep alive. 2849 CompilerThread* ct = (CompilerThread*)this; 2850 if (ct->env() != NULL) { 2851 ct->env()->metadata_do(f); 2852 } 2853 CompileTask* task = ct->task(); 2854 if (task != NULL) { 2855 task->metadata_do(f); 2856 } 2857 } 2858 } 2859 2860 // Printing 2861 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2862 switch (_thread_state) { 2863 case _thread_uninitialized: return "_thread_uninitialized"; 2864 case _thread_new: return "_thread_new"; 2865 case _thread_new_trans: return "_thread_new_trans"; 2866 case _thread_in_native: return "_thread_in_native"; 2867 case _thread_in_native_trans: return "_thread_in_native_trans"; 2868 case _thread_in_vm: return "_thread_in_vm"; 2869 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2870 case _thread_in_Java: return "_thread_in_Java"; 2871 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2872 case _thread_blocked: return "_thread_blocked"; 2873 case _thread_blocked_trans: return "_thread_blocked_trans"; 2874 default: return "unknown thread state"; 2875 } 2876 } 2877 2878 #ifndef PRODUCT 2879 void JavaThread::print_thread_state_on(outputStream *st) const { 2880 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2881 }; 2882 void JavaThread::print_thread_state() const { 2883 print_thread_state_on(tty); 2884 } 2885 #endif // PRODUCT 2886 2887 // Called by Threads::print() for VM_PrintThreads operation 2888 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2889 st->print_raw("\""); 2890 st->print_raw(get_thread_name()); 2891 st->print_raw("\" "); 2892 oop thread_oop = threadObj(); 2893 if (thread_oop != NULL) { 2894 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2895 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2896 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2897 } 2898 Thread::print_on(st, print_extended_info); 2899 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2900 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2901 if (thread_oop != NULL) { 2902 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2903 } 2904 #ifndef PRODUCT 2905 print_thread_state_on(st); 2906 _safepoint_state->print_on(st); 2907 #endif // PRODUCT 2908 if (is_Compiler_thread()) { 2909 CompileTask *task = ((CompilerThread*)this)->task(); 2910 if (task != NULL) { 2911 st->print(" Compiling: "); 2912 task->print(st, NULL, true, false); 2913 } else { 2914 st->print(" No compile task"); 2915 } 2916 st->cr(); 2917 } 2918 } 2919 2920 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2921 st->print("%s", get_thread_name_string(buf, buflen)); 2922 } 2923 2924 // Called by fatal error handler. The difference between this and 2925 // JavaThread::print() is that we can't grab lock or allocate memory. 2926 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2927 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2928 oop thread_obj = threadObj(); 2929 if (thread_obj != NULL) { 2930 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2931 } 2932 st->print(" ["); 2933 st->print("%s", _get_thread_state_name(_thread_state)); 2934 if (osthread()) { 2935 st->print(", id=%d", osthread()->thread_id()); 2936 } 2937 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2938 p2i(stack_end()), p2i(stack_base())); 2939 st->print("]"); 2940 2941 ThreadsSMRSupport::print_info_on(this, st); 2942 return; 2943 } 2944 2945 // Verification 2946 2947 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2948 2949 void JavaThread::verify() { 2950 // Verify oops in the thread. 2951 oops_do(&VerifyOopClosure::verify_oop, NULL); 2952 2953 // Verify the stack frames. 2954 frames_do(frame_verify); 2955 } 2956 2957 // CR 6300358 (sub-CR 2137150) 2958 // Most callers of this method assume that it can't return NULL but a 2959 // thread may not have a name whilst it is in the process of attaching to 2960 // the VM - see CR 6412693, and there are places where a JavaThread can be 2961 // seen prior to having it's threadObj set (eg JNI attaching threads and 2962 // if vm exit occurs during initialization). These cases can all be accounted 2963 // for such that this method never returns NULL. 2964 const char* JavaThread::get_thread_name() const { 2965 #ifdef ASSERT 2966 // early safepoints can hit while current thread does not yet have TLS 2967 if (!SafepointSynchronize::is_at_safepoint()) { 2968 Thread *cur = Thread::current(); 2969 if (!(cur->is_Java_thread() && cur == this)) { 2970 // Current JavaThreads are allowed to get their own name without 2971 // the Threads_lock. 2972 assert_locked_or_safepoint(Threads_lock); 2973 } 2974 } 2975 #endif // ASSERT 2976 return get_thread_name_string(); 2977 } 2978 2979 // Returns a non-NULL representation of this thread's name, or a suitable 2980 // descriptive string if there is no set name 2981 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2982 const char* name_str; 2983 oop thread_obj = threadObj(); 2984 if (thread_obj != NULL) { 2985 oop name = java_lang_Thread::name(thread_obj); 2986 if (name != NULL) { 2987 if (buf == NULL) { 2988 name_str = java_lang_String::as_utf8_string(name); 2989 } else { 2990 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2991 } 2992 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2993 name_str = "<no-name - thread is attaching>"; 2994 } else { 2995 name_str = Thread::name(); 2996 } 2997 } else { 2998 name_str = Thread::name(); 2999 } 3000 assert(name_str != NULL, "unexpected NULL thread name"); 3001 return name_str; 3002 } 3003 3004 3005 const char* JavaThread::get_threadgroup_name() const { 3006 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3007 oop thread_obj = threadObj(); 3008 if (thread_obj != NULL) { 3009 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3010 if (thread_group != NULL) { 3011 // ThreadGroup.name can be null 3012 return java_lang_ThreadGroup::name(thread_group); 3013 } 3014 } 3015 return NULL; 3016 } 3017 3018 const char* JavaThread::get_parent_name() const { 3019 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3020 oop thread_obj = threadObj(); 3021 if (thread_obj != NULL) { 3022 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3023 if (thread_group != NULL) { 3024 oop parent = java_lang_ThreadGroup::parent(thread_group); 3025 if (parent != NULL) { 3026 // ThreadGroup.name can be null 3027 return java_lang_ThreadGroup::name(parent); 3028 } 3029 } 3030 } 3031 return NULL; 3032 } 3033 3034 ThreadPriority JavaThread::java_priority() const { 3035 oop thr_oop = threadObj(); 3036 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3037 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3038 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3039 return priority; 3040 } 3041 3042 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3043 3044 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3045 // Link Java Thread object <-> C++ Thread 3046 3047 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3048 // and put it into a new Handle. The Handle "thread_oop" can then 3049 // be used to pass the C++ thread object to other methods. 3050 3051 // Set the Java level thread object (jthread) field of the 3052 // new thread (a JavaThread *) to C++ thread object using the 3053 // "thread_oop" handle. 3054 3055 // Set the thread field (a JavaThread *) of the 3056 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3057 3058 Handle thread_oop(Thread::current(), 3059 JNIHandles::resolve_non_null(jni_thread)); 3060 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3061 "must be initialized"); 3062 set_threadObj(thread_oop()); 3063 java_lang_Thread::set_thread(thread_oop(), this); 3064 3065 if (prio == NoPriority) { 3066 prio = java_lang_Thread::priority(thread_oop()); 3067 assert(prio != NoPriority, "A valid priority should be present"); 3068 } 3069 3070 // Push the Java priority down to the native thread; needs Threads_lock 3071 Thread::set_priority(this, prio); 3072 3073 // Add the new thread to the Threads list and set it in motion. 3074 // We must have threads lock in order to call Threads::add. 3075 // It is crucial that we do not block before the thread is 3076 // added to the Threads list for if a GC happens, then the java_thread oop 3077 // will not be visited by GC. 3078 Threads::add(this); 3079 } 3080 3081 oop JavaThread::current_park_blocker() { 3082 // Support for JSR-166 locks 3083 oop thread_oop = threadObj(); 3084 if (thread_oop != NULL && 3085 JDK_Version::current().supports_thread_park_blocker()) { 3086 return java_lang_Thread::park_blocker(thread_oop); 3087 } 3088 return NULL; 3089 } 3090 3091 3092 void JavaThread::print_stack_on(outputStream* st) { 3093 if (!has_last_Java_frame()) return; 3094 ResourceMark rm; 3095 HandleMark hm; 3096 3097 RegisterMap reg_map(this); 3098 vframe* start_vf = last_java_vframe(®_map); 3099 int count = 0; 3100 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3101 if (f->is_java_frame()) { 3102 javaVFrame* jvf = javaVFrame::cast(f); 3103 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3104 3105 // Print out lock information 3106 if (JavaMonitorsInStackTrace) { 3107 jvf->print_lock_info_on(st, count); 3108 } 3109 } else { 3110 // Ignore non-Java frames 3111 } 3112 3113 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3114 count++; 3115 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3116 } 3117 } 3118 3119 3120 // JVMTI PopFrame support 3121 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3122 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3123 if (in_bytes(size_in_bytes) != 0) { 3124 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3125 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3126 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3127 } 3128 } 3129 3130 void* JavaThread::popframe_preserved_args() { 3131 return _popframe_preserved_args; 3132 } 3133 3134 ByteSize JavaThread::popframe_preserved_args_size() { 3135 return in_ByteSize(_popframe_preserved_args_size); 3136 } 3137 3138 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3139 int sz = in_bytes(popframe_preserved_args_size()); 3140 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3141 return in_WordSize(sz / wordSize); 3142 } 3143 3144 void JavaThread::popframe_free_preserved_args() { 3145 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3146 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3147 _popframe_preserved_args = NULL; 3148 _popframe_preserved_args_size = 0; 3149 } 3150 3151 #ifndef PRODUCT 3152 3153 void JavaThread::trace_frames() { 3154 tty->print_cr("[Describe stack]"); 3155 int frame_no = 1; 3156 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3157 tty->print(" %d. ", frame_no++); 3158 fst.current()->print_value_on(tty, this); 3159 tty->cr(); 3160 } 3161 } 3162 3163 class PrintAndVerifyOopClosure: public OopClosure { 3164 protected: 3165 template <class T> inline void do_oop_work(T* p) { 3166 oop obj = RawAccess<>::oop_load(p); 3167 if (obj == NULL) return; 3168 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3169 if (oopDesc::is_oop_or_null(obj)) { 3170 if (obj->is_objArray()) { 3171 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3172 } else { 3173 obj->print(); 3174 } 3175 } else { 3176 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3177 } 3178 tty->cr(); 3179 } 3180 public: 3181 virtual void do_oop(oop* p) { do_oop_work(p); } 3182 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3183 }; 3184 3185 3186 static void oops_print(frame* f, const RegisterMap *map) { 3187 PrintAndVerifyOopClosure print; 3188 f->print_value(); 3189 f->oops_do(&print, NULL, (RegisterMap*)map); 3190 } 3191 3192 // Print our all the locations that contain oops and whether they are 3193 // valid or not. This useful when trying to find the oldest frame 3194 // where an oop has gone bad since the frame walk is from youngest to 3195 // oldest. 3196 void JavaThread::trace_oops() { 3197 tty->print_cr("[Trace oops]"); 3198 frames_do(oops_print); 3199 } 3200 3201 3202 #ifdef ASSERT 3203 // Print or validate the layout of stack frames 3204 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3205 ResourceMark rm; 3206 PRESERVE_EXCEPTION_MARK; 3207 FrameValues values; 3208 int frame_no = 0; 3209 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3210 fst.current()->describe(values, ++frame_no); 3211 if (depth == frame_no) break; 3212 } 3213 if (validate_only) { 3214 values.validate(); 3215 } else { 3216 tty->print_cr("[Describe stack layout]"); 3217 values.print(this); 3218 } 3219 } 3220 #endif 3221 3222 void JavaThread::trace_stack_from(vframe* start_vf) { 3223 ResourceMark rm; 3224 int vframe_no = 1; 3225 for (vframe* f = start_vf; f; f = f->sender()) { 3226 if (f->is_java_frame()) { 3227 javaVFrame::cast(f)->print_activation(vframe_no++); 3228 } else { 3229 f->print(); 3230 } 3231 if (vframe_no > StackPrintLimit) { 3232 tty->print_cr("...<more frames>..."); 3233 return; 3234 } 3235 } 3236 } 3237 3238 3239 void JavaThread::trace_stack() { 3240 if (!has_last_Java_frame()) return; 3241 ResourceMark rm; 3242 HandleMark hm; 3243 RegisterMap reg_map(this); 3244 trace_stack_from(last_java_vframe(®_map)); 3245 } 3246 3247 3248 #endif // PRODUCT 3249 3250 3251 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3252 assert(reg_map != NULL, "a map must be given"); 3253 frame f = last_frame(); 3254 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3255 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3256 } 3257 return NULL; 3258 } 3259 3260 3261 Klass* JavaThread::security_get_caller_class(int depth) { 3262 vframeStream vfst(this); 3263 vfst.security_get_caller_frame(depth); 3264 if (!vfst.at_end()) { 3265 return vfst.method()->method_holder(); 3266 } 3267 return NULL; 3268 } 3269 3270 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3271 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3272 CompileBroker::compiler_thread_loop(); 3273 } 3274 3275 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3276 NMethodSweeper::sweeper_loop(); 3277 } 3278 3279 // Create a CompilerThread 3280 CompilerThread::CompilerThread(CompileQueue* queue, 3281 CompilerCounters* counters) 3282 : JavaThread(&compiler_thread_entry) { 3283 _env = NULL; 3284 _log = NULL; 3285 _task = NULL; 3286 _queue = queue; 3287 _counters = counters; 3288 _buffer_blob = NULL; 3289 _compiler = NULL; 3290 3291 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3292 resource_area()->bias_to(mtCompiler); 3293 3294 #ifndef PRODUCT 3295 _ideal_graph_printer = NULL; 3296 #endif 3297 } 3298 3299 CompilerThread::~CompilerThread() { 3300 // Free buffer blob, if allocated 3301 if (get_buffer_blob() != NULL) { 3302 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); 3303 CodeCache::free(get_buffer_blob()); 3304 } 3305 // Delete objects which were allocated on heap. 3306 delete _counters; 3307 } 3308 3309 bool CompilerThread::can_call_java() const { 3310 return _compiler != NULL && _compiler->is_jvmci(); 3311 } 3312 3313 // Create sweeper thread 3314 CodeCacheSweeperThread::CodeCacheSweeperThread() 3315 : JavaThread(&sweeper_thread_entry) { 3316 _scanned_compiled_method = NULL; 3317 } 3318 3319 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3320 JavaThread::oops_do(f, cf); 3321 if (_scanned_compiled_method != NULL && cf != NULL) { 3322 // Safepoints can occur when the sweeper is scanning an nmethod so 3323 // process it here to make sure it isn't unloaded in the middle of 3324 // a scan. 3325 cf->do_code_blob(_scanned_compiled_method); 3326 } 3327 } 3328 3329 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3330 JavaThread::nmethods_do(cf); 3331 if (_scanned_compiled_method != NULL && cf != NULL) { 3332 // Safepoints can occur when the sweeper is scanning an nmethod so 3333 // process it here to make sure it isn't unloaded in the middle of 3334 // a scan. 3335 cf->do_code_blob(_scanned_compiled_method); 3336 } 3337 } 3338 3339 3340 // ======= Threads ======== 3341 3342 // The Threads class links together all active threads, and provides 3343 // operations over all threads. It is protected by the Threads_lock, 3344 // which is also used in other global contexts like safepointing. 3345 // ThreadsListHandles are used to safely perform operations on one 3346 // or more threads without the risk of the thread exiting during the 3347 // operation. 3348 // 3349 // Note: The Threads_lock is currently more widely used than we 3350 // would like. We are actively migrating Threads_lock uses to other 3351 // mechanisms in order to reduce Threads_lock contention. 3352 3353 JavaThread* Threads::_thread_list = NULL; 3354 int Threads::_number_of_threads = 0; 3355 int Threads::_number_of_non_daemon_threads = 0; 3356 int Threads::_return_code = 0; 3357 int Threads::_thread_claim_parity = 0; 3358 size_t JavaThread::_stack_size_at_create = 0; 3359 3360 #ifdef ASSERT 3361 bool Threads::_vm_complete = false; 3362 #endif 3363 3364 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3365 Prefetch::read((void*)addr, prefetch_interval); 3366 return *addr; 3367 } 3368 3369 // Possibly the ugliest for loop the world has seen. C++ does not allow 3370 // multiple types in the declaration section of the for loop. In this case 3371 // we are only dealing with pointers and hence can cast them. It looks ugly 3372 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3373 #define DO_JAVA_THREADS(LIST, X) \ 3374 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3375 *MACRO_list = (JavaThread*)(LIST), \ 3376 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3377 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3378 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3379 MACRO_current_p != MACRO_end; \ 3380 MACRO_current_p++, \ 3381 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3382 3383 // All JavaThreads 3384 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3385 3386 // All non-JavaThreads (i.e., every non-JavaThread in the system). 3387 void Threads::non_java_threads_do(ThreadClosure* tc) { 3388 // Someday we could have a table or list of all non-JavaThreads. 3389 // For now, just manually iterate through them. 3390 tc->do_thread(VMThread::vm_thread()); 3391 if (Universe::heap() != NULL) { 3392 Universe::heap()->gc_threads_do(tc); 3393 } 3394 WatcherThread *wt = WatcherThread::watcher_thread(); 3395 // Strictly speaking, the following NULL check isn't sufficient to make sure 3396 // the data for WatcherThread is still valid upon being examined. However, 3397 // considering that WatchThread terminates when the VM is on the way to 3398 // exit at safepoint, the chance of the above is extremely small. The right 3399 // way to prevent termination of WatcherThread would be to acquire 3400 // Terminator_lock, but we can't do that without violating the lock rank 3401 // checking in some cases. 3402 if (wt != NULL) { 3403 tc->do_thread(wt); 3404 } 3405 3406 #if INCLUDE_JFR 3407 Thread* sampler_thread = Jfr::sampler_thread(); 3408 if (sampler_thread != NULL) { 3409 tc->do_thread(sampler_thread); 3410 } 3411 3412 #endif 3413 3414 // If CompilerThreads ever become non-JavaThreads, add them here 3415 } 3416 3417 // All JavaThreads 3418 void Threads::java_threads_do(ThreadClosure* tc) { 3419 assert_locked_or_safepoint(Threads_lock); 3420 // ALL_JAVA_THREADS iterates through all JavaThreads. 3421 ALL_JAVA_THREADS(p) { 3422 tc->do_thread(p); 3423 } 3424 } 3425 3426 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3427 assert_locked_or_safepoint(Threads_lock); 3428 java_threads_do(tc); 3429 tc->do_thread(VMThread::vm_thread()); 3430 } 3431 3432 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3433 void Threads::threads_do(ThreadClosure* tc) { 3434 assert_locked_or_safepoint(Threads_lock); 3435 java_threads_do(tc); 3436 non_java_threads_do(tc); 3437 } 3438 3439 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3440 int cp = Threads::thread_claim_parity(); 3441 ALL_JAVA_THREADS(p) { 3442 if (p->claim_oops_do(is_par, cp)) { 3443 tc->do_thread(p); 3444 } 3445 } 3446 VMThread* vmt = VMThread::vm_thread(); 3447 if (vmt->claim_oops_do(is_par, cp)) { 3448 tc->do_thread(vmt); 3449 } 3450 } 3451 3452 // The system initialization in the library has three phases. 3453 // 3454 // Phase 1: java.lang.System class initialization 3455 // java.lang.System is a primordial class loaded and initialized 3456 // by the VM early during startup. java.lang.System.<clinit> 3457 // only does registerNatives and keeps the rest of the class 3458 // initialization work later until thread initialization completes. 3459 // 3460 // System.initPhase1 initializes the system properties, the static 3461 // fields in, out, and err. Set up java signal handlers, OS-specific 3462 // system settings, and thread group of the main thread. 3463 static void call_initPhase1(TRAPS) { 3464 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3465 JavaValue result(T_VOID); 3466 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3467 vmSymbols::void_method_signature(), CHECK); 3468 } 3469 3470 // Phase 2. Module system initialization 3471 // This will initialize the module system. Only java.base classes 3472 // can be loaded until phase 2 completes. 3473 // 3474 // Call System.initPhase2 after the compiler initialization and jsr292 3475 // classes get initialized because module initialization runs a lot of java 3476 // code, that for performance reasons, should be compiled. Also, this will 3477 // enable the startup code to use lambda and other language features in this 3478 // phase and onward. 3479 // 3480 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3481 static void call_initPhase2(TRAPS) { 3482 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3483 3484 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3485 3486 JavaValue result(T_INT); 3487 JavaCallArguments args; 3488 args.push_int(DisplayVMOutputToStderr); 3489 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3490 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3491 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3492 if (result.get_jint() != JNI_OK) { 3493 vm_exit_during_initialization(); // no message or exception 3494 } 3495 3496 universe_post_module_init(); 3497 } 3498 3499 // Phase 3. final setup - set security manager, system class loader and TCCL 3500 // 3501 // This will instantiate and set the security manager, set the system class 3502 // loader as well as the thread context class loader. The security manager 3503 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3504 // other modules or the application's classpath. 3505 static void call_initPhase3(TRAPS) { 3506 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3507 JavaValue result(T_VOID); 3508 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3509 vmSymbols::void_method_signature(), CHECK); 3510 } 3511 3512 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3513 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3514 3515 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3516 create_vm_init_libraries(); 3517 } 3518 3519 initialize_class(vmSymbols::java_lang_String(), CHECK); 3520 3521 // Inject CompactStrings value after the static initializers for String ran. 3522 java_lang_String::set_compact_strings(CompactStrings); 3523 3524 // Initialize java_lang.System (needed before creating the thread) 3525 initialize_class(vmSymbols::java_lang_System(), CHECK); 3526 // The VM creates & returns objects of this class. Make sure it's initialized. 3527 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3528 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3529 Handle thread_group = create_initial_thread_group(CHECK); 3530 Universe::set_main_thread_group(thread_group()); 3531 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3532 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3533 main_thread->set_threadObj(thread_object); 3534 // Set thread status to running since main thread has 3535 // been started and running. 3536 java_lang_Thread::set_thread_status(thread_object, 3537 java_lang_Thread::RUNNABLE); 3538 3539 // The VM creates objects of this class. 3540 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3541 3542 // The VM preresolves methods to these classes. Make sure that they get initialized 3543 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3544 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3545 3546 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3547 call_initPhase1(CHECK); 3548 3549 // get the Java runtime name after java.lang.System is initialized 3550 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3551 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3552 3553 // an instance of OutOfMemory exception has been allocated earlier 3554 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3555 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3556 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3557 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3558 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3559 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3560 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3561 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3562 } 3563 3564 void Threads::initialize_jsr292_core_classes(TRAPS) { 3565 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3566 3567 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3568 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3569 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3570 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3571 } 3572 3573 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3574 extern void JDK_Version_init(); 3575 3576 // Preinitialize version info. 3577 VM_Version::early_initialize(); 3578 3579 // Check version 3580 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3581 3582 // Initialize library-based TLS 3583 ThreadLocalStorage::init(); 3584 3585 // Initialize the output stream module 3586 ostream_init(); 3587 3588 // Process java launcher properties. 3589 Arguments::process_sun_java_launcher_properties(args); 3590 3591 // Initialize the os module 3592 os::init(); 3593 3594 // Record VM creation timing statistics 3595 TraceVmCreationTime create_vm_timer; 3596 create_vm_timer.start(); 3597 3598 // Initialize system properties. 3599 Arguments::init_system_properties(); 3600 3601 // So that JDK version can be used as a discriminator when parsing arguments 3602 JDK_Version_init(); 3603 3604 // Update/Initialize System properties after JDK version number is known 3605 Arguments::init_version_specific_system_properties(); 3606 3607 // Make sure to initialize log configuration *before* parsing arguments 3608 LogConfiguration::initialize(create_vm_timer.begin_time()); 3609 3610 // Parse arguments 3611 // Note: this internally calls os::init_container_support() 3612 jint parse_result = Arguments::parse(args); 3613 if (parse_result != JNI_OK) return parse_result; 3614 3615 os::init_before_ergo(); 3616 3617 jint ergo_result = Arguments::apply_ergo(); 3618 if (ergo_result != JNI_OK) return ergo_result; 3619 3620 // Final check of all ranges after ergonomics which may change values. 3621 if (!JVMFlagRangeList::check_ranges()) { 3622 return JNI_EINVAL; 3623 } 3624 3625 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3626 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3627 if (!constraint_result) { 3628 return JNI_EINVAL; 3629 } 3630 3631 JVMFlagWriteableList::mark_startup(); 3632 3633 if (PauseAtStartup) { 3634 os::pause(); 3635 } 3636 3637 HOTSPOT_VM_INIT_BEGIN(); 3638 3639 // Timing (must come after argument parsing) 3640 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3641 3642 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3643 // Initialize assert poison page mechanism. 3644 if (ShowRegistersOnAssert) { 3645 initialize_assert_poison(); 3646 } 3647 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3648 3649 // Initialize the os module after parsing the args 3650 jint os_init_2_result = os::init_2(); 3651 if (os_init_2_result != JNI_OK) return os_init_2_result; 3652 3653 SafepointMechanism::initialize(); 3654 3655 jint adjust_after_os_result = Arguments::adjust_after_os(); 3656 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3657 3658 // Initialize output stream logging 3659 ostream_init_log(); 3660 3661 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3662 // Must be before create_vm_init_agents() 3663 if (Arguments::init_libraries_at_startup()) { 3664 convert_vm_init_libraries_to_agents(); 3665 } 3666 3667 // Launch -agentlib/-agentpath and converted -Xrun agents 3668 if (Arguments::init_agents_at_startup()) { 3669 create_vm_init_agents(); 3670 } 3671 3672 // Initialize Threads state 3673 _thread_list = NULL; 3674 _number_of_threads = 0; 3675 _number_of_non_daemon_threads = 0; 3676 3677 // Initialize global data structures and create system classes in heap 3678 vm_init_globals(); 3679 3680 #if INCLUDE_JVMCI 3681 if (JVMCICounterSize > 0) { 3682 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3683 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3684 } else { 3685 JavaThread::_jvmci_old_thread_counters = NULL; 3686 } 3687 #endif // INCLUDE_JVMCI 3688 3689 // Attach the main thread to this os thread 3690 JavaThread* main_thread = new JavaThread(); 3691 main_thread->set_thread_state(_thread_in_vm); 3692 main_thread->initialize_thread_current(); 3693 // must do this before set_active_handles 3694 main_thread->record_stack_base_and_size(); 3695 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3696 3697 if (!main_thread->set_as_starting_thread()) { 3698 vm_shutdown_during_initialization( 3699 "Failed necessary internal allocation. Out of swap space"); 3700 main_thread->smr_delete(); 3701 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3702 return JNI_ENOMEM; 3703 } 3704 3705 // Enable guard page *after* os::create_main_thread(), otherwise it would 3706 // crash Linux VM, see notes in os_linux.cpp. 3707 main_thread->create_stack_guard_pages(); 3708 3709 // Initialize Java-Level synchronization subsystem 3710 ObjectMonitor::Initialize(); 3711 3712 // Initialize global modules 3713 jint status = init_globals(); 3714 if (status != JNI_OK) { 3715 main_thread->smr_delete(); 3716 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3717 return status; 3718 } 3719 3720 JFR_ONLY(Jfr::on_vm_init();) 3721 3722 // Should be done after the heap is fully created 3723 main_thread->cache_global_variables(); 3724 3725 HandleMark hm; 3726 3727 { MutexLocker mu(Threads_lock); 3728 Threads::add(main_thread); 3729 } 3730 3731 // Any JVMTI raw monitors entered in onload will transition into 3732 // real raw monitor. VM is setup enough here for raw monitor enter. 3733 JvmtiExport::transition_pending_onload_raw_monitors(); 3734 3735 // Create the VMThread 3736 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3737 3738 VMThread::create(); 3739 Thread* vmthread = VMThread::vm_thread(); 3740 3741 if (!os::create_thread(vmthread, os::vm_thread)) { 3742 vm_exit_during_initialization("Cannot create VM thread. " 3743 "Out of system resources."); 3744 } 3745 3746 // Wait for the VM thread to become ready, and VMThread::run to initialize 3747 // Monitors can have spurious returns, must always check another state flag 3748 { 3749 MutexLocker ml(Notify_lock); 3750 os::start_thread(vmthread); 3751 while (vmthread->active_handles() == NULL) { 3752 Notify_lock->wait(); 3753 } 3754 } 3755 } 3756 3757 assert(Universe::is_fully_initialized(), "not initialized"); 3758 if (VerifyDuringStartup) { 3759 // Make sure we're starting with a clean slate. 3760 VM_Verify verify_op; 3761 VMThread::execute(&verify_op); 3762 } 3763 3764 // We need this to update the java.vm.info property in case any flags used 3765 // to initially define it have been changed. This is needed for both CDS and 3766 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3767 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3768 // This update must happen before we initialize the java classes, but 3769 // after any initialization logic that might modify the flags. 3770 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3771 3772 Thread* THREAD = Thread::current(); 3773 3774 // Always call even when there are not JVMTI environments yet, since environments 3775 // may be attached late and JVMTI must track phases of VM execution 3776 JvmtiExport::enter_early_start_phase(); 3777 3778 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3779 JvmtiExport::post_early_vm_start(); 3780 3781 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3782 3783 quicken_jni_functions(); 3784 3785 // No more stub generation allowed after that point. 3786 StubCodeDesc::freeze(); 3787 3788 // Set flag that basic initialization has completed. Used by exceptions and various 3789 // debug stuff, that does not work until all basic classes have been initialized. 3790 set_init_completed(); 3791 3792 LogConfiguration::post_initialize(); 3793 Metaspace::post_initialize(); 3794 3795 HOTSPOT_VM_INIT_END(); 3796 3797 // record VM initialization completion time 3798 #if INCLUDE_MANAGEMENT 3799 Management::record_vm_init_completed(); 3800 #endif // INCLUDE_MANAGEMENT 3801 3802 // Signal Dispatcher needs to be started before VMInit event is posted 3803 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3804 3805 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3806 if (!DisableAttachMechanism) { 3807 AttachListener::vm_start(); 3808 if (StartAttachListener || AttachListener::init_at_startup()) { 3809 AttachListener::init(); 3810 } 3811 } 3812 3813 // Launch -Xrun agents 3814 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3815 // back-end can launch with -Xdebug -Xrunjdwp. 3816 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3817 create_vm_init_libraries(); 3818 } 3819 3820 if (CleanChunkPoolAsync) { 3821 Chunk::start_chunk_pool_cleaner_task(); 3822 } 3823 3824 // initialize compiler(s) 3825 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3826 #if INCLUDE_JVMCI 3827 bool force_JVMCI_intialization = false; 3828 if (EnableJVMCI) { 3829 // Initialize JVMCI eagerly when it is explicitly requested. 3830 // Or when JVMCIPrintProperties is enabled. 3831 // The JVMCI Java initialization code will read this flag and 3832 // do the printing if it's set. 3833 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3834 3835 if (!force_JVMCI_intialization) { 3836 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3837 // compilations via JVMCI will not actually block until JVMCI is initialized. 3838 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3839 } 3840 } 3841 #endif 3842 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3843 // Postpone completion of compiler initialization to after JVMCI 3844 // is initialized to avoid timeouts of blocking compilations. 3845 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3846 CompileBroker::compilation_init_phase2(); 3847 } 3848 #endif 3849 3850 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3851 // It is done after compilers are initialized, because otherwise compilations of 3852 // signature polymorphic MH intrinsics can be missed 3853 // (see SystemDictionary::find_method_handle_intrinsic). 3854 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3855 3856 // This will initialize the module system. Only java.base classes can be 3857 // loaded until phase 2 completes 3858 call_initPhase2(CHECK_JNI_ERR); 3859 3860 // Always call even when there are not JVMTI environments yet, since environments 3861 // may be attached late and JVMTI must track phases of VM execution 3862 JvmtiExport::enter_start_phase(); 3863 3864 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3865 JvmtiExport::post_vm_start(); 3866 3867 // Final system initialization including security manager and system class loader 3868 call_initPhase3(CHECK_JNI_ERR); 3869 3870 // cache the system and platform class loaders 3871 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3872 3873 #if INCLUDE_CDS 3874 if (DumpSharedSpaces) { 3875 // capture the module path info from the ModuleEntryTable 3876 ClassLoader::initialize_module_path(THREAD); 3877 } 3878 #endif 3879 3880 #if INCLUDE_JVMCI 3881 if (force_JVMCI_intialization) { 3882 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3883 CompileBroker::compilation_init_phase2(); 3884 } 3885 #endif 3886 3887 // Always call even when there are not JVMTI environments yet, since environments 3888 // may be attached late and JVMTI must track phases of VM execution 3889 JvmtiExport::enter_live_phase(); 3890 3891 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3892 JvmtiExport::post_vm_initialized(); 3893 3894 JFR_ONLY(Jfr::on_vm_start();) 3895 3896 #if INCLUDE_MANAGEMENT 3897 Management::initialize(THREAD); 3898 3899 if (HAS_PENDING_EXCEPTION) { 3900 // management agent fails to start possibly due to 3901 // configuration problem and is responsible for printing 3902 // stack trace if appropriate. Simply exit VM. 3903 vm_exit(1); 3904 } 3905 #endif // INCLUDE_MANAGEMENT 3906 3907 if (MemProfiling) MemProfiler::engage(); 3908 StatSampler::engage(); 3909 if (CheckJNICalls) JniPeriodicChecker::engage(); 3910 3911 BiasedLocking::init(); 3912 3913 #if INCLUDE_RTM_OPT 3914 RTMLockingCounters::init(); 3915 #endif 3916 3917 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3918 call_postVMInitHook(THREAD); 3919 // The Java side of PostVMInitHook.run must deal with all 3920 // exceptions and provide means of diagnosis. 3921 if (HAS_PENDING_EXCEPTION) { 3922 CLEAR_PENDING_EXCEPTION; 3923 } 3924 } 3925 3926 { 3927 MutexLocker ml(PeriodicTask_lock); 3928 // Make sure the WatcherThread can be started by WatcherThread::start() 3929 // or by dynamic enrollment. 3930 WatcherThread::make_startable(); 3931 // Start up the WatcherThread if there are any periodic tasks 3932 // NOTE: All PeriodicTasks should be registered by now. If they 3933 // aren't, late joiners might appear to start slowly (we might 3934 // take a while to process their first tick). 3935 if (PeriodicTask::num_tasks() > 0) { 3936 WatcherThread::start(); 3937 } 3938 } 3939 3940 create_vm_timer.end(); 3941 #ifdef ASSERT 3942 _vm_complete = true; 3943 #endif 3944 3945 if (DumpSharedSpaces) { 3946 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3947 ShouldNotReachHere(); 3948 } 3949 3950 return JNI_OK; 3951 } 3952 3953 // type for the Agent_OnLoad and JVM_OnLoad entry points 3954 extern "C" { 3955 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3956 } 3957 // Find a command line agent library and return its entry point for 3958 // -agentlib: -agentpath: -Xrun 3959 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3960 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3961 const char *on_load_symbols[], 3962 size_t num_symbol_entries) { 3963 OnLoadEntry_t on_load_entry = NULL; 3964 void *library = NULL; 3965 3966 if (!agent->valid()) { 3967 char buffer[JVM_MAXPATHLEN]; 3968 char ebuf[1024] = ""; 3969 const char *name = agent->name(); 3970 const char *msg = "Could not find agent library "; 3971 3972 // First check to see if agent is statically linked into executable 3973 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3974 library = agent->os_lib(); 3975 } else if (agent->is_absolute_path()) { 3976 library = os::dll_load(name, ebuf, sizeof ebuf); 3977 if (library == NULL) { 3978 const char *sub_msg = " in absolute path, with error: "; 3979 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3980 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3981 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3982 // If we can't find the agent, exit. 3983 vm_exit_during_initialization(buf, NULL); 3984 FREE_C_HEAP_ARRAY(char, buf); 3985 } 3986 } else { 3987 // Try to load the agent from the standard dll directory 3988 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3989 name)) { 3990 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3991 } 3992 if (library == NULL) { // Try the library path directory. 3993 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 3994 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3995 } 3996 if (library == NULL) { 3997 const char *sub_msg = " on the library path, with error: "; 3998 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 3999 4000 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4001 strlen(ebuf) + strlen(sub_msg2) + 1; 4002 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4003 if (!agent->is_instrument_lib()) { 4004 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4005 } else { 4006 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4007 } 4008 // If we can't find the agent, exit. 4009 vm_exit_during_initialization(buf, NULL); 4010 FREE_C_HEAP_ARRAY(char, buf); 4011 } 4012 } 4013 } 4014 agent->set_os_lib(library); 4015 agent->set_valid(); 4016 } 4017 4018 // Find the OnLoad function. 4019 on_load_entry = 4020 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4021 false, 4022 on_load_symbols, 4023 num_symbol_entries)); 4024 return on_load_entry; 4025 } 4026 4027 // Find the JVM_OnLoad entry point 4028 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4029 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4030 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4031 } 4032 4033 // Find the Agent_OnLoad entry point 4034 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4035 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4036 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4037 } 4038 4039 // For backwards compatibility with -Xrun 4040 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4041 // treated like -agentpath: 4042 // Must be called before agent libraries are created 4043 void Threads::convert_vm_init_libraries_to_agents() { 4044 AgentLibrary* agent; 4045 AgentLibrary* next; 4046 4047 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4048 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4049 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4050 4051 // If there is an JVM_OnLoad function it will get called later, 4052 // otherwise see if there is an Agent_OnLoad 4053 if (on_load_entry == NULL) { 4054 on_load_entry = lookup_agent_on_load(agent); 4055 if (on_load_entry != NULL) { 4056 // switch it to the agent list -- so that Agent_OnLoad will be called, 4057 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4058 Arguments::convert_library_to_agent(agent); 4059 } else { 4060 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4061 } 4062 } 4063 } 4064 } 4065 4066 // Create agents for -agentlib: -agentpath: and converted -Xrun 4067 // Invokes Agent_OnLoad 4068 // Called very early -- before JavaThreads exist 4069 void Threads::create_vm_init_agents() { 4070 extern struct JavaVM_ main_vm; 4071 AgentLibrary* agent; 4072 4073 JvmtiExport::enter_onload_phase(); 4074 4075 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4076 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4077 4078 if (on_load_entry != NULL) { 4079 // Invoke the Agent_OnLoad function 4080 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4081 if (err != JNI_OK) { 4082 vm_exit_during_initialization("agent library failed to init", agent->name()); 4083 } 4084 } else { 4085 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4086 } 4087 } 4088 JvmtiExport::enter_primordial_phase(); 4089 } 4090 4091 extern "C" { 4092 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4093 } 4094 4095 void Threads::shutdown_vm_agents() { 4096 // Send any Agent_OnUnload notifications 4097 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4098 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4099 extern struct JavaVM_ main_vm; 4100 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4101 4102 // Find the Agent_OnUnload function. 4103 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4104 os::find_agent_function(agent, 4105 false, 4106 on_unload_symbols, 4107 num_symbol_entries)); 4108 4109 // Invoke the Agent_OnUnload function 4110 if (unload_entry != NULL) { 4111 JavaThread* thread = JavaThread::current(); 4112 ThreadToNativeFromVM ttn(thread); 4113 HandleMark hm(thread); 4114 (*unload_entry)(&main_vm); 4115 } 4116 } 4117 } 4118 4119 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4120 // Invokes JVM_OnLoad 4121 void Threads::create_vm_init_libraries() { 4122 extern struct JavaVM_ main_vm; 4123 AgentLibrary* agent; 4124 4125 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4126 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4127 4128 if (on_load_entry != NULL) { 4129 // Invoke the JVM_OnLoad function 4130 JavaThread* thread = JavaThread::current(); 4131 ThreadToNativeFromVM ttn(thread); 4132 HandleMark hm(thread); 4133 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4134 if (err != JNI_OK) { 4135 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4136 } 4137 } else { 4138 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4139 } 4140 } 4141 } 4142 4143 4144 // Last thread running calls java.lang.Shutdown.shutdown() 4145 void JavaThread::invoke_shutdown_hooks() { 4146 HandleMark hm(this); 4147 4148 // We could get here with a pending exception, if so clear it now. 4149 if (this->has_pending_exception()) { 4150 this->clear_pending_exception(); 4151 } 4152 4153 EXCEPTION_MARK; 4154 Klass* shutdown_klass = 4155 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4156 THREAD); 4157 if (shutdown_klass != NULL) { 4158 // SystemDictionary::resolve_or_null will return null if there was 4159 // an exception. If we cannot load the Shutdown class, just don't 4160 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4161 // won't be run. Note that if a shutdown hook was registered, 4162 // the Shutdown class would have already been loaded 4163 // (Runtime.addShutdownHook will load it). 4164 JavaValue result(T_VOID); 4165 JavaCalls::call_static(&result, 4166 shutdown_klass, 4167 vmSymbols::shutdown_method_name(), 4168 vmSymbols::void_method_signature(), 4169 THREAD); 4170 } 4171 CLEAR_PENDING_EXCEPTION; 4172 } 4173 4174 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4175 // the program falls off the end of main(). Another VM exit path is through 4176 // vm_exit() when the program calls System.exit() to return a value or when 4177 // there is a serious error in VM. The two shutdown paths are not exactly 4178 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4179 // and VM_Exit op at VM level. 4180 // 4181 // Shutdown sequence: 4182 // + Shutdown native memory tracking if it is on 4183 // + Wait until we are the last non-daemon thread to execute 4184 // <-- every thing is still working at this moment --> 4185 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4186 // shutdown hooks 4187 // + Call before_exit(), prepare for VM exit 4188 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4189 // currently the only user of this mechanism is File.deleteOnExit()) 4190 // > stop StatSampler, watcher thread, CMS threads, 4191 // post thread end and vm death events to JVMTI, 4192 // stop signal thread 4193 // + Call JavaThread::exit(), it will: 4194 // > release JNI handle blocks, remove stack guard pages 4195 // > remove this thread from Threads list 4196 // <-- no more Java code from this thread after this point --> 4197 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4198 // the compiler threads at safepoint 4199 // <-- do not use anything that could get blocked by Safepoint --> 4200 // + Disable tracing at JNI/JVM barriers 4201 // + Set _vm_exited flag for threads that are still running native code 4202 // + Delete this thread 4203 // + Call exit_globals() 4204 // > deletes tty 4205 // > deletes PerfMemory resources 4206 // + Return to caller 4207 4208 bool Threads::destroy_vm() { 4209 JavaThread* thread = JavaThread::current(); 4210 4211 #ifdef ASSERT 4212 _vm_complete = false; 4213 #endif 4214 // Wait until we are the last non-daemon thread to execute 4215 { MutexLocker nu(Threads_lock); 4216 while (Threads::number_of_non_daemon_threads() > 1) 4217 // This wait should make safepoint checks, wait without a timeout, 4218 // and wait as a suspend-equivalent condition. 4219 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4220 Mutex::_as_suspend_equivalent_flag); 4221 } 4222 4223 EventShutdown e; 4224 if (e.should_commit()) { 4225 e.set_reason("No remaining non-daemon Java threads"); 4226 e.commit(); 4227 } 4228 4229 // Hang forever on exit if we are reporting an error. 4230 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4231 os::infinite_sleep(); 4232 } 4233 os::wait_for_keypress_at_exit(); 4234 4235 // run Java level shutdown hooks 4236 thread->invoke_shutdown_hooks(); 4237 4238 before_exit(thread); 4239 4240 thread->exit(true); 4241 // thread will never call smr_delete, instead of implicit cancel 4242 // in wait_for_vm_thread_exit we do it explicit. 4243 thread->cancel_handshake(); 4244 4245 // Stop VM thread. 4246 { 4247 // 4945125 The vm thread comes to a safepoint during exit. 4248 // GC vm_operations can get caught at the safepoint, and the 4249 // heap is unparseable if they are caught. Grab the Heap_lock 4250 // to prevent this. The GC vm_operations will not be able to 4251 // queue until after the vm thread is dead. After this point, 4252 // we'll never emerge out of the safepoint before the VM exits. 4253 4254 MutexLocker ml(Heap_lock); 4255 4256 VMThread::wait_for_vm_thread_exit(); 4257 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4258 VMThread::destroy(); 4259 } 4260 4261 // Now, all Java threads are gone except daemon threads. Daemon threads 4262 // running Java code or in VM are stopped by the Safepoint. However, 4263 // daemon threads executing native code are still running. But they 4264 // will be stopped at native=>Java/VM barriers. Note that we can't 4265 // simply kill or suspend them, as it is inherently deadlock-prone. 4266 4267 VM_Exit::set_vm_exited(); 4268 4269 // Clean up ideal graph printers after the VMThread has started 4270 // the final safepoint which will block all the Compiler threads. 4271 // Note that this Thread has already logically exited so the 4272 // clean_up() function's use of a JavaThreadIteratorWithHandle 4273 // would be a problem except set_vm_exited() has remembered the 4274 // shutdown thread which is granted a policy exception. 4275 #if defined(COMPILER2) && !defined(PRODUCT) 4276 IdealGraphPrinter::clean_up(); 4277 #endif 4278 4279 notify_vm_shutdown(); 4280 4281 // We are after VM_Exit::set_vm_exited() so we can't call 4282 // thread->smr_delete() or we will block on the Threads_lock. 4283 // Deleting the shutdown thread here is safe because another 4284 // JavaThread cannot have an active ThreadsListHandle for 4285 // this JavaThread. 4286 delete thread; 4287 4288 #if INCLUDE_JVMCI 4289 if (JVMCICounterSize > 0) { 4290 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4291 } 4292 #endif 4293 4294 // exit_globals() will delete tty 4295 exit_globals(); 4296 4297 LogConfiguration::finalize(); 4298 4299 return true; 4300 } 4301 4302 4303 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4304 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4305 return is_supported_jni_version(version); 4306 } 4307 4308 4309 jboolean Threads::is_supported_jni_version(jint version) { 4310 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4311 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4312 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4313 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4314 if (version == JNI_VERSION_9) return JNI_TRUE; 4315 if (version == JNI_VERSION_10) return JNI_TRUE; 4316 return JNI_FALSE; 4317 } 4318 4319 4320 void Threads::add(JavaThread* p, bool force_daemon) { 4321 // The threads lock must be owned at this point 4322 assert_locked_or_safepoint(Threads_lock); 4323 4324 BarrierSet::barrier_set()->on_thread_attach(p); 4325 4326 p->set_next(_thread_list); 4327 _thread_list = p; 4328 4329 // Once a JavaThread is added to the Threads list, smr_delete() has 4330 // to be used to delete it. Otherwise we can just delete it directly. 4331 p->set_on_thread_list(); 4332 4333 _number_of_threads++; 4334 oop threadObj = p->threadObj(); 4335 bool daemon = true; 4336 // Bootstrapping problem: threadObj can be null for initial 4337 // JavaThread (or for threads attached via JNI) 4338 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4339 _number_of_non_daemon_threads++; 4340 daemon = false; 4341 } 4342 4343 ThreadService::add_thread(p, daemon); 4344 4345 // Maintain fast thread list 4346 ThreadsSMRSupport::add_thread(p); 4347 4348 // Possible GC point. 4349 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4350 } 4351 4352 void Threads::remove(JavaThread* p) { 4353 4354 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4355 ObjectSynchronizer::omFlush(p); 4356 4357 // Extra scope needed for Thread_lock, so we can check 4358 // that we do not remove thread without safepoint code notice 4359 { MutexLocker ml(Threads_lock); 4360 4361 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4362 4363 // Maintain fast thread list 4364 ThreadsSMRSupport::remove_thread(p); 4365 4366 JavaThread* current = _thread_list; 4367 JavaThread* prev = NULL; 4368 4369 while (current != p) { 4370 prev = current; 4371 current = current->next(); 4372 } 4373 4374 if (prev) { 4375 prev->set_next(current->next()); 4376 } else { 4377 _thread_list = p->next(); 4378 } 4379 4380 _number_of_threads--; 4381 oop threadObj = p->threadObj(); 4382 bool daemon = true; 4383 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4384 _number_of_non_daemon_threads--; 4385 daemon = false; 4386 4387 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4388 // on destroy_vm will wake up. 4389 if (number_of_non_daemon_threads() == 1) { 4390 Threads_lock->notify_all(); 4391 } 4392 } 4393 ThreadService::remove_thread(p, daemon); 4394 4395 // Make sure that safepoint code disregard this thread. This is needed since 4396 // the thread might mess around with locks after this point. This can cause it 4397 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4398 // of this thread since it is removed from the queue. 4399 p->set_terminated_value(); 4400 } // unlock Threads_lock 4401 4402 // Since Events::log uses a lock, we grab it outside the Threads_lock 4403 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4404 } 4405 4406 // Operations on the Threads list for GC. These are not explicitly locked, 4407 // but the garbage collector must provide a safe context for them to run. 4408 // In particular, these things should never be called when the Threads_lock 4409 // is held by some other thread. (Note: the Safepoint abstraction also 4410 // uses the Threads_lock to guarantee this property. It also makes sure that 4411 // all threads gets blocked when exiting or starting). 4412 4413 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4414 ALL_JAVA_THREADS(p) { 4415 p->oops_do(f, cf); 4416 } 4417 VMThread::vm_thread()->oops_do(f, cf); 4418 } 4419 4420 void Threads::change_thread_claim_parity() { 4421 // Set the new claim parity. 4422 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4423 "Not in range."); 4424 _thread_claim_parity++; 4425 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4426 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4427 "Not in range."); 4428 } 4429 4430 #ifdef ASSERT 4431 void Threads::assert_all_threads_claimed() { 4432 ALL_JAVA_THREADS(p) { 4433 const int thread_parity = p->oops_do_parity(); 4434 assert((thread_parity == _thread_claim_parity), 4435 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4436 } 4437 VMThread* vmt = VMThread::vm_thread(); 4438 const int thread_parity = vmt->oops_do_parity(); 4439 assert((thread_parity == _thread_claim_parity), 4440 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4441 } 4442 #endif // ASSERT 4443 4444 class ParallelOopsDoThreadClosure : public ThreadClosure { 4445 private: 4446 OopClosure* _f; 4447 CodeBlobClosure* _cf; 4448 public: 4449 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4450 void do_thread(Thread* t) { 4451 t->oops_do(_f, _cf); 4452 } 4453 }; 4454 4455 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4456 ParallelOopsDoThreadClosure tc(f, cf); 4457 possibly_parallel_threads_do(is_par, &tc); 4458 } 4459 4460 void Threads::nmethods_do(CodeBlobClosure* cf) { 4461 ALL_JAVA_THREADS(p) { 4462 // This is used by the code cache sweeper to mark nmethods that are active 4463 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4464 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4465 if(!p->is_Code_cache_sweeper_thread()) { 4466 p->nmethods_do(cf); 4467 } 4468 } 4469 } 4470 4471 void Threads::metadata_do(void f(Metadata*)) { 4472 ALL_JAVA_THREADS(p) { 4473 p->metadata_do(f); 4474 } 4475 } 4476 4477 class ThreadHandlesClosure : public ThreadClosure { 4478 void (*_f)(Metadata*); 4479 public: 4480 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4481 virtual void do_thread(Thread* thread) { 4482 thread->metadata_handles_do(_f); 4483 } 4484 }; 4485 4486 void Threads::metadata_handles_do(void f(Metadata*)) { 4487 // Only walk the Handles in Thread. 4488 ThreadHandlesClosure handles_closure(f); 4489 threads_do(&handles_closure); 4490 } 4491 4492 void Threads::deoptimized_wrt_marked_nmethods() { 4493 ALL_JAVA_THREADS(p) { 4494 p->deoptimized_wrt_marked_nmethods(); 4495 } 4496 } 4497 4498 4499 // Get count Java threads that are waiting to enter the specified monitor. 4500 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4501 int count, 4502 address monitor) { 4503 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4504 4505 int i = 0; 4506 DO_JAVA_THREADS(t_list, p) { 4507 if (!p->can_call_java()) continue; 4508 4509 address pending = (address)p->current_pending_monitor(); 4510 if (pending == monitor) { // found a match 4511 if (i < count) result->append(p); // save the first count matches 4512 i++; 4513 } 4514 } 4515 4516 return result; 4517 } 4518 4519 4520 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4521 address owner) { 4522 // NULL owner means not locked so we can skip the search 4523 if (owner == NULL) return NULL; 4524 4525 DO_JAVA_THREADS(t_list, p) { 4526 // first, see if owner is the address of a Java thread 4527 if (owner == (address)p) return p; 4528 } 4529 4530 // Cannot assert on lack of success here since this function may be 4531 // used by code that is trying to report useful problem information 4532 // like deadlock detection. 4533 if (UseHeavyMonitors) return NULL; 4534 4535 // If we didn't find a matching Java thread and we didn't force use of 4536 // heavyweight monitors, then the owner is the stack address of the 4537 // Lock Word in the owning Java thread's stack. 4538 // 4539 JavaThread* the_owner = NULL; 4540 DO_JAVA_THREADS(t_list, q) { 4541 if (q->is_lock_owned(owner)) { 4542 the_owner = q; 4543 break; 4544 } 4545 } 4546 4547 // cannot assert on lack of success here; see above comment 4548 return the_owner; 4549 } 4550 4551 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4552 void Threads::print_on(outputStream* st, bool print_stacks, 4553 bool internal_format, bool print_concurrent_locks, 4554 bool print_extended_info) { 4555 char buf[32]; 4556 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4557 4558 st->print_cr("Full thread dump %s (%s %s):", 4559 Abstract_VM_Version::vm_name(), 4560 Abstract_VM_Version::vm_release(), 4561 Abstract_VM_Version::vm_info_string()); 4562 st->cr(); 4563 4564 #if INCLUDE_SERVICES 4565 // Dump concurrent locks 4566 ConcurrentLocksDump concurrent_locks; 4567 if (print_concurrent_locks) { 4568 concurrent_locks.dump_at_safepoint(); 4569 } 4570 #endif // INCLUDE_SERVICES 4571 4572 ThreadsSMRSupport::print_info_on(st); 4573 st->cr(); 4574 4575 ALL_JAVA_THREADS(p) { 4576 ResourceMark rm; 4577 p->print_on(st, print_extended_info); 4578 if (print_stacks) { 4579 if (internal_format) { 4580 p->trace_stack(); 4581 } else { 4582 p->print_stack_on(st); 4583 } 4584 } 4585 st->cr(); 4586 #if INCLUDE_SERVICES 4587 if (print_concurrent_locks) { 4588 concurrent_locks.print_locks_on(p, st); 4589 } 4590 #endif // INCLUDE_SERVICES 4591 } 4592 4593 VMThread::vm_thread()->print_on(st); 4594 st->cr(); 4595 Universe::heap()->print_gc_threads_on(st); 4596 WatcherThread* wt = WatcherThread::watcher_thread(); 4597 if (wt != NULL) { 4598 wt->print_on(st); 4599 st->cr(); 4600 } 4601 4602 st->flush(); 4603 } 4604 4605 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4606 int buflen, bool* found_current) { 4607 if (this_thread != NULL) { 4608 bool is_current = (current == this_thread); 4609 *found_current = *found_current || is_current; 4610 st->print("%s", is_current ? "=>" : " "); 4611 4612 st->print(PTR_FORMAT, p2i(this_thread)); 4613 st->print(" "); 4614 this_thread->print_on_error(st, buf, buflen); 4615 st->cr(); 4616 } 4617 } 4618 4619 class PrintOnErrorClosure : public ThreadClosure { 4620 outputStream* _st; 4621 Thread* _current; 4622 char* _buf; 4623 int _buflen; 4624 bool* _found_current; 4625 public: 4626 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4627 int buflen, bool* found_current) : 4628 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4629 4630 virtual void do_thread(Thread* thread) { 4631 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4632 } 4633 }; 4634 4635 // Threads::print_on_error() is called by fatal error handler. It's possible 4636 // that VM is not at safepoint and/or current thread is inside signal handler. 4637 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4638 // memory (even in resource area), it might deadlock the error handler. 4639 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4640 int buflen) { 4641 ThreadsSMRSupport::print_info_on(st); 4642 st->cr(); 4643 4644 bool found_current = false; 4645 st->print_cr("Java Threads: ( => current thread )"); 4646 ALL_JAVA_THREADS(thread) { 4647 print_on_error(thread, st, current, buf, buflen, &found_current); 4648 } 4649 st->cr(); 4650 4651 st->print_cr("Other Threads:"); 4652 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4653 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4654 4655 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4656 Universe::heap()->gc_threads_do(&print_closure); 4657 4658 if (!found_current) { 4659 st->cr(); 4660 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4661 current->print_on_error(st, buf, buflen); 4662 st->cr(); 4663 } 4664 st->cr(); 4665 4666 st->print_cr("Threads with active compile tasks:"); 4667 print_threads_compiling(st, buf, buflen); 4668 } 4669 4670 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4671 ALL_JAVA_THREADS(thread) { 4672 if (thread->is_Compiler_thread()) { 4673 CompilerThread* ct = (CompilerThread*) thread; 4674 4675 // Keep task in local variable for NULL check. 4676 // ct->_task might be set to NULL by concurring compiler thread 4677 // because it completed the compilation. The task is never freed, 4678 // though, just returned to a free list. 4679 CompileTask* task = ct->task(); 4680 if (task != NULL) { 4681 thread->print_name_on_error(st, buf, buflen); 4682 task->print(st, NULL, true, true); 4683 } 4684 } 4685 } 4686 } 4687 4688 4689 // Internal SpinLock and Mutex 4690 // Based on ParkEvent 4691 4692 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4693 // 4694 // We employ SpinLocks _only for low-contention, fixed-length 4695 // short-duration critical sections where we're concerned 4696 // about native mutex_t or HotSpot Mutex:: latency. 4697 // The mux construct provides a spin-then-block mutual exclusion 4698 // mechanism. 4699 // 4700 // Testing has shown that contention on the ListLock guarding gFreeList 4701 // is common. If we implement ListLock as a simple SpinLock it's common 4702 // for the JVM to devolve to yielding with little progress. This is true 4703 // despite the fact that the critical sections protected by ListLock are 4704 // extremely short. 4705 // 4706 // TODO-FIXME: ListLock should be of type SpinLock. 4707 // We should make this a 1st-class type, integrated into the lock 4708 // hierarchy as leaf-locks. Critically, the SpinLock structure 4709 // should have sufficient padding to avoid false-sharing and excessive 4710 // cache-coherency traffic. 4711 4712 4713 typedef volatile int SpinLockT; 4714 4715 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4716 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4717 return; // normal fast-path return 4718 } 4719 4720 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4721 TEVENT(SpinAcquire - ctx); 4722 int ctr = 0; 4723 int Yields = 0; 4724 for (;;) { 4725 while (*adr != 0) { 4726 ++ctr; 4727 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4728 if (Yields > 5) { 4729 os::naked_short_sleep(1); 4730 } else { 4731 os::naked_yield(); 4732 ++Yields; 4733 } 4734 } else { 4735 SpinPause(); 4736 } 4737 } 4738 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4739 } 4740 } 4741 4742 void Thread::SpinRelease(volatile int * adr) { 4743 assert(*adr != 0, "invariant"); 4744 OrderAccess::fence(); // guarantee at least release consistency. 4745 // Roach-motel semantics. 4746 // It's safe if subsequent LDs and STs float "up" into the critical section, 4747 // but prior LDs and STs within the critical section can't be allowed 4748 // to reorder or float past the ST that releases the lock. 4749 // Loads and stores in the critical section - which appear in program 4750 // order before the store that releases the lock - must also appear 4751 // before the store that releases the lock in memory visibility order. 4752 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4753 // the ST of 0 into the lock-word which releases the lock, so fence 4754 // more than covers this on all platforms. 4755 *adr = 0; 4756 } 4757 4758 // muxAcquire and muxRelease: 4759 // 4760 // * muxAcquire and muxRelease support a single-word lock-word construct. 4761 // The LSB of the word is set IFF the lock is held. 4762 // The remainder of the word points to the head of a singly-linked list 4763 // of threads blocked on the lock. 4764 // 4765 // * The current implementation of muxAcquire-muxRelease uses its own 4766 // dedicated Thread._MuxEvent instance. If we're interested in 4767 // minimizing the peak number of extant ParkEvent instances then 4768 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4769 // as certain invariants were satisfied. Specifically, care would need 4770 // to be taken with regards to consuming unpark() "permits". 4771 // A safe rule of thumb is that a thread would never call muxAcquire() 4772 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4773 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4774 // consume an unpark() permit intended for monitorenter, for instance. 4775 // One way around this would be to widen the restricted-range semaphore 4776 // implemented in park(). Another alternative would be to provide 4777 // multiple instances of the PlatformEvent() for each thread. One 4778 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4779 // 4780 // * Usage: 4781 // -- Only as leaf locks 4782 // -- for short-term locking only as muxAcquire does not perform 4783 // thread state transitions. 4784 // 4785 // Alternatives: 4786 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4787 // but with parking or spin-then-park instead of pure spinning. 4788 // * Use Taura-Oyama-Yonenzawa locks. 4789 // * It's possible to construct a 1-0 lock if we encode the lockword as 4790 // (List,LockByte). Acquire will CAS the full lockword while Release 4791 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4792 // acquiring threads use timers (ParkTimed) to detect and recover from 4793 // the stranding window. Thread/Node structures must be aligned on 256-byte 4794 // boundaries by using placement-new. 4795 // * Augment MCS with advisory back-link fields maintained with CAS(). 4796 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4797 // The validity of the backlinks must be ratified before we trust the value. 4798 // If the backlinks are invalid the exiting thread must back-track through the 4799 // the forward links, which are always trustworthy. 4800 // * Add a successor indication. The LockWord is currently encoded as 4801 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4802 // to provide the usual futile-wakeup optimization. 4803 // See RTStt for details. 4804 // 4805 4806 4807 const intptr_t LOCKBIT = 1; 4808 4809 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4810 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4811 if (w == 0) return; 4812 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4813 return; 4814 } 4815 4816 TEVENT(muxAcquire - Contention); 4817 ParkEvent * const Self = Thread::current()->_MuxEvent; 4818 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4819 for (;;) { 4820 int its = (os::is_MP() ? 100 : 0) + 1; 4821 4822 // Optional spin phase: spin-then-park strategy 4823 while (--its >= 0) { 4824 w = *Lock; 4825 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4826 return; 4827 } 4828 } 4829 4830 Self->reset(); 4831 Self->OnList = intptr_t(Lock); 4832 // The following fence() isn't _strictly necessary as the subsequent 4833 // CAS() both serializes execution and ratifies the fetched *Lock value. 4834 OrderAccess::fence(); 4835 for (;;) { 4836 w = *Lock; 4837 if ((w & LOCKBIT) == 0) { 4838 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4839 Self->OnList = 0; // hygiene - allows stronger asserts 4840 return; 4841 } 4842 continue; // Interference -- *Lock changed -- Just retry 4843 } 4844 assert(w & LOCKBIT, "invariant"); 4845 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4846 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4847 } 4848 4849 while (Self->OnList != 0) { 4850 Self->park(); 4851 } 4852 } 4853 } 4854 4855 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4856 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4857 if (w == 0) return; 4858 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4859 return; 4860 } 4861 4862 TEVENT(muxAcquire - Contention); 4863 ParkEvent * ReleaseAfter = NULL; 4864 if (ev == NULL) { 4865 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4866 } 4867 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4868 for (;;) { 4869 guarantee(ev->OnList == 0, "invariant"); 4870 int its = (os::is_MP() ? 100 : 0) + 1; 4871 4872 // Optional spin phase: spin-then-park strategy 4873 while (--its >= 0) { 4874 w = *Lock; 4875 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4876 if (ReleaseAfter != NULL) { 4877 ParkEvent::Release(ReleaseAfter); 4878 } 4879 return; 4880 } 4881 } 4882 4883 ev->reset(); 4884 ev->OnList = intptr_t(Lock); 4885 // The following fence() isn't _strictly necessary as the subsequent 4886 // CAS() both serializes execution and ratifies the fetched *Lock value. 4887 OrderAccess::fence(); 4888 for (;;) { 4889 w = *Lock; 4890 if ((w & LOCKBIT) == 0) { 4891 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4892 ev->OnList = 0; 4893 // We call ::Release while holding the outer lock, thus 4894 // artificially lengthening the critical section. 4895 // Consider deferring the ::Release() until the subsequent unlock(), 4896 // after we've dropped the outer lock. 4897 if (ReleaseAfter != NULL) { 4898 ParkEvent::Release(ReleaseAfter); 4899 } 4900 return; 4901 } 4902 continue; // Interference -- *Lock changed -- Just retry 4903 } 4904 assert(w & LOCKBIT, "invariant"); 4905 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4906 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4907 } 4908 4909 while (ev->OnList != 0) { 4910 ev->park(); 4911 } 4912 } 4913 } 4914 4915 // Release() must extract a successor from the list and then wake that thread. 4916 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4917 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4918 // Release() would : 4919 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4920 // (B) Extract a successor from the private list "in-hand" 4921 // (C) attempt to CAS() the residual back into *Lock over null. 4922 // If there were any newly arrived threads and the CAS() would fail. 4923 // In that case Release() would detach the RATs, re-merge the list in-hand 4924 // with the RATs and repeat as needed. Alternately, Release() might 4925 // detach and extract a successor, but then pass the residual list to the wakee. 4926 // The wakee would be responsible for reattaching and remerging before it 4927 // competed for the lock. 4928 // 4929 // Both "pop" and DMR are immune from ABA corruption -- there can be 4930 // multiple concurrent pushers, but only one popper or detacher. 4931 // This implementation pops from the head of the list. This is unfair, 4932 // but tends to provide excellent throughput as hot threads remain hot. 4933 // (We wake recently run threads first). 4934 // 4935 // All paths through muxRelease() will execute a CAS. 4936 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4937 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4938 // executed within the critical section are complete and globally visible before the 4939 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4940 void Thread::muxRelease(volatile intptr_t * Lock) { 4941 for (;;) { 4942 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4943 assert(w & LOCKBIT, "invariant"); 4944 if (w == LOCKBIT) return; 4945 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4946 assert(List != NULL, "invariant"); 4947 assert(List->OnList == intptr_t(Lock), "invariant"); 4948 ParkEvent * const nxt = List->ListNext; 4949 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4950 4951 // The following CAS() releases the lock and pops the head element. 4952 // The CAS() also ratifies the previously fetched lock-word value. 4953 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4954 continue; 4955 } 4956 List->OnList = 0; 4957 OrderAccess::fence(); 4958 List->unpark(); 4959 return; 4960 } 4961 } 4962 4963 4964 void Threads::verify() { 4965 ALL_JAVA_THREADS(p) { 4966 p->verify(); 4967 } 4968 VMThread* thread = VMThread::vm_thread(); 4969 if (thread != NULL) thread->verify(); 4970 }