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.inline.hpp" 84 #include "runtime/osThread.hpp" 85 #include "runtime/prefetch.inline.hpp" 86 #include "runtime/safepoint.hpp" 87 #include "runtime/safepointMechanism.inline.hpp" 88 #include "runtime/sharedRuntime.hpp" 89 #include "runtime/statSampler.hpp" 90 #include "runtime/stubRoutines.hpp" 91 #include "runtime/sweeper.hpp" 92 #include "runtime/task.hpp" 93 #include "runtime/thread.inline.hpp" 94 #include "runtime/threadCritical.hpp" 95 #include "runtime/threadSMR.inline.hpp" 96 #include "runtime/timer.hpp" 97 #include "runtime/timerTrace.hpp" 98 #include "runtime/vframe.inline.hpp" 99 #include "runtime/vframeArray.hpp" 100 #include "runtime/vframe_hp.hpp" 101 #include "runtime/vmThread.hpp" 102 #include "runtime/vm_operations.hpp" 103 #include "runtime/vm_version.hpp" 104 #include "services/attachListener.hpp" 105 #include "services/management.hpp" 106 #include "services/memTracker.hpp" 107 #include "services/threadService.hpp" 108 #include "utilities/align.hpp" 109 #include "utilities/copy.hpp" 110 #include "utilities/defaultStream.hpp" 111 #include "utilities/dtrace.hpp" 112 #include "utilities/events.hpp" 113 #include "utilities/macros.hpp" 114 #include "utilities/preserveException.hpp" 115 #include "utilities/vmError.hpp" 116 #if INCLUDE_JVMCI 117 #include "jvmci/jvmciCompiler.hpp" 118 #include "jvmci/jvmciRuntime.hpp" 119 #include "logging/logHandle.hpp" 120 #endif 121 #ifdef COMPILER1 122 #include "c1/c1_Compiler.hpp" 123 #endif 124 #ifdef COMPILER2 125 #include "opto/c2compiler.hpp" 126 #include "opto/idealGraphPrinter.hpp" 127 #endif 128 #if INCLUDE_RTM_OPT 129 #include "runtime/rtmLocking.hpp" 130 #endif 131 #if INCLUDE_JFR 132 #include "jfr/jfr.hpp" 133 #endif 134 135 // Initialization after module runtime initialization 136 void universe_post_module_init(); // must happen after call_initPhase2 137 138 #ifdef DTRACE_ENABLED 139 140 // Only bother with this argument setup if dtrace is available 141 142 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 143 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 144 145 #define DTRACE_THREAD_PROBE(probe, javathread) \ 146 { \ 147 ResourceMark rm(this); \ 148 int len = 0; \ 149 const char* name = (javathread)->get_thread_name(); \ 150 len = strlen(name); \ 151 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 152 (char *) name, len, \ 153 java_lang_Thread::thread_id((javathread)->threadObj()), \ 154 (uintptr_t) (javathread)->osthread()->thread_id(), \ 155 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 156 } 157 158 #else // ndef DTRACE_ENABLED 159 160 #define DTRACE_THREAD_PROBE(probe, javathread) 161 162 #endif // ndef DTRACE_ENABLED 163 164 #ifndef USE_LIBRARY_BASED_TLS_ONLY 165 // Current thread is maintained as a thread-local variable 166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 167 #endif 168 // Class hierarchy 169 // - Thread 170 // - VMThread 171 // - WatcherThread 172 // - ConcurrentMarkSweepThread 173 // - JavaThread 174 // - CompilerThread 175 176 // ======= Thread ======== 177 // Support for forcing alignment of thread objects for biased locking 178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 179 if (UseBiasedLocking) { 180 const int alignment = markOopDesc::biased_lock_alignment; 181 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 182 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 183 : AllocateHeap(aligned_size, flags, CURRENT_PC, 184 AllocFailStrategy::RETURN_NULL); 185 void* aligned_addr = align_up(real_malloc_addr, alignment); 186 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 187 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 188 "JavaThread alignment code overflowed allocated storage"); 189 if (aligned_addr != real_malloc_addr) { 190 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 191 p2i(real_malloc_addr), 192 p2i(aligned_addr)); 193 } 194 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 195 return aligned_addr; 196 } else { 197 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 198 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 199 } 200 } 201 202 void Thread::operator delete(void* p) { 203 if (UseBiasedLocking) { 204 FreeHeap(((Thread*) p)->_real_malloc_address); 205 } else { 206 FreeHeap(p); 207 } 208 } 209 210 void JavaThread::smr_delete() { 211 if (_on_thread_list) { 212 ThreadsSMRSupport::smr_delete(this); 213 } else { 214 delete this; 215 } 216 } 217 218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 219 // JavaThread 220 221 222 Thread::Thread() { 223 // stack and get_thread 224 set_stack_base(NULL); 225 set_stack_size(0); 226 set_self_raw_id(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 240 // This initial value ==> never claimed. 241 _oops_do_parity = 0; 242 _threads_hazard_ptr = NULL; 243 _threads_list_ptr = NULL; 244 _nested_threads_hazard_ptr_cnt = 0; 245 _rcu_counter = 0; 246 247 // the handle mark links itself to last_handle_mark 248 new HandleMark(this); 249 250 // plain initialization 251 debug_only(_owned_locks = NULL;) 252 debug_only(_allow_allocation_count = 0;) 253 NOT_PRODUCT(_allow_safepoint_count = 0;) 254 NOT_PRODUCT(_skip_gcalot = false;) 255 _jvmti_env_iteration_count = 0; 256 set_allocated_bytes(0); 257 _vm_operation_started_count = 0; 258 _vm_operation_completed_count = 0; 259 _current_pending_monitor = NULL; 260 _current_pending_monitor_is_from_java = true; 261 _current_waiting_monitor = NULL; 262 _num_nested_signal = 0; 263 omFreeList = NULL; 264 omFreeCount = 0; 265 omFreeProvision = 32; 266 omInUseList = NULL; 267 omInUseCount = 0; 268 269 #ifdef ASSERT 270 _visited_for_critical_count = false; 271 #endif 272 273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 274 Monitor::_safepoint_check_sometimes); 275 _suspend_flags = 0; 276 277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 278 _hashStateX = os::random(); 279 _hashStateY = 842502087; 280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 281 _hashStateW = 273326509; 282 283 _OnTrap = 0; 284 _schedctl = NULL; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _SleepEvent = ParkEvent::Allocate(this); 297 _MutexEvent = ParkEvent::Allocate(this); 298 _MuxEvent = ParkEvent::Allocate(this); 299 300 #ifdef CHECK_UNHANDLED_OOPS 301 if (CheckUnhandledOops) { 302 _unhandled_oops = new UnhandledOops(this); 303 } 304 #endif // CHECK_UNHANDLED_OOPS 305 #ifdef ASSERT 306 if (UseBiasedLocking) { 307 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 308 assert(this == _real_malloc_address || 309 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 310 "bug in forced alignment of thread objects"); 311 } 312 #endif // ASSERT 313 314 // Notify the barrier set that a thread is being created. Note that the 315 // main thread is created before a barrier set is available. The call to 316 // BarrierSet::on_thread_create() for the main thread is therefore deferred 317 // until it calls BarrierSet::set_barrier_set(). 318 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 319 if (barrier_set != NULL) { 320 barrier_set->on_thread_create(this); 321 } 322 } 323 324 void Thread::initialize_thread_current() { 325 #ifndef USE_LIBRARY_BASED_TLS_ONLY 326 assert(_thr_current == NULL, "Thread::current already initialized"); 327 _thr_current = this; 328 #endif 329 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 330 ThreadLocalStorage::set_thread(this); 331 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 332 } 333 334 void Thread::clear_thread_current() { 335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 336 #ifndef USE_LIBRARY_BASED_TLS_ONLY 337 _thr_current = NULL; 338 #endif 339 ThreadLocalStorage::set_thread(NULL); 340 } 341 342 void Thread::record_stack_base_and_size() { 343 set_stack_base(os::current_stack_base()); 344 set_stack_size(os::current_stack_size()); 345 // CR 7190089: on Solaris, primordial thread's stack is adjusted 346 // in initialize_thread(). Without the adjustment, stack size is 347 // incorrect if stack is set to unlimited (ulimit -s unlimited). 348 // So far, only Solaris has real implementation of initialize_thread(). 349 // 350 // set up any platform-specific state. 351 os::initialize_thread(this); 352 353 // Set stack limits after thread is initialized. 354 if (is_Java_thread()) { 355 ((JavaThread*) this)->set_stack_overflow_limit(); 356 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 357 } 358 #if INCLUDE_NMT 359 // record thread's native stack, stack grows downward 360 MemTracker::record_thread_stack(stack_end(), stack_size()); 361 #endif // INCLUDE_NMT 362 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 363 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 364 os::current_thread_id(), p2i(stack_base() - stack_size()), 365 p2i(stack_base()), stack_size()/1024); 366 } 367 368 369 Thread::~Thread() { 370 JFR_ONLY(Jfr::on_thread_destruct(this);) 371 372 // Notify the barrier set that a thread is being destroyed. Note that a barrier 373 // set might not be available if we encountered errors during bootstrapping. 374 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 375 if (barrier_set != NULL) { 376 barrier_set->on_thread_destroy(this); 377 } 378 379 380 // stack_base can be NULL if the thread is never started or exited before 381 // record_stack_base_and_size called. Although, we would like to ensure 382 // that all started threads do call record_stack_base_and_size(), there is 383 // not proper way to enforce that. 384 #if INCLUDE_NMT 385 if (_stack_base != NULL) { 386 MemTracker::release_thread_stack(stack_end(), stack_size()); 387 #ifdef ASSERT 388 set_stack_base(NULL); 389 #endif 390 } 391 #endif // INCLUDE_NMT 392 393 // deallocate data structures 394 delete resource_area(); 395 // since the handle marks are using the handle area, we have to deallocated the root 396 // handle mark before deallocating the thread's handle area, 397 assert(last_handle_mark() != NULL, "check we have an element"); 398 delete last_handle_mark(); 399 assert(last_handle_mark() == NULL, "check we have reached the end"); 400 401 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 402 // We NULL out the fields for good hygiene. 403 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 404 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 405 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 406 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 407 408 delete handle_area(); 409 delete metadata_handles(); 410 411 // SR_handler uses this as a termination indicator - 412 // needs to happen before os::free_thread() 413 delete _SR_lock; 414 _SR_lock = NULL; 415 416 // osthread() can be NULL, if creation of thread failed. 417 if (osthread() != NULL) os::free_thread(osthread()); 418 419 // clear Thread::current if thread is deleting itself. 420 // Needed to ensure JNI correctly detects non-attached threads. 421 if (this == Thread::current()) { 422 clear_thread_current(); 423 } 424 425 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 426 } 427 428 // NOTE: dummy function for assertion purpose. 429 void Thread::run() { 430 ShouldNotReachHere(); 431 } 432 433 #ifdef ASSERT 434 // A JavaThread is considered "dangling" if it is not the current 435 // thread, has been added the Threads list, the system is not at a 436 // safepoint and the Thread is not "protected". 437 // 438 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 439 assert(!thread->is_Java_thread() || Thread::current() == thread || 440 !((JavaThread *) thread)->on_thread_list() || 441 SafepointSynchronize::is_at_safepoint() || 442 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 443 "possibility of dangling Thread pointer"); 444 } 445 #endif 446 447 ThreadPriority Thread::get_priority(const Thread* const thread) { 448 ThreadPriority priority; 449 // Can return an error! 450 (void)os::get_priority(thread, priority); 451 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 452 return priority; 453 } 454 455 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 456 debug_only(check_for_dangling_thread_pointer(thread);) 457 // Can return an error! 458 (void)os::set_priority(thread, priority); 459 } 460 461 462 void Thread::start(Thread* thread) { 463 // Start is different from resume in that its safety is guaranteed by context or 464 // being called from a Java method synchronized on the Thread object. 465 if (!DisableStartThread) { 466 if (thread->is_Java_thread()) { 467 // Initialize the thread state to RUNNABLE before starting this thread. 468 // Can not set it after the thread started because we do not know the 469 // exact thread state at that time. It could be in MONITOR_WAIT or 470 // in SLEEPING or some other state. 471 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 472 java_lang_Thread::RUNNABLE); 473 } 474 os::start_thread(thread); 475 } 476 } 477 478 // Enqueue a VM_Operation to do the job for us - sometime later 479 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 480 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 481 VMThread::execute(vm_stop); 482 } 483 484 485 // Check if an external suspend request has completed (or has been 486 // cancelled). Returns true if the thread is externally suspended and 487 // false otherwise. 488 // 489 // The bits parameter returns information about the code path through 490 // the routine. Useful for debugging: 491 // 492 // set in is_ext_suspend_completed(): 493 // 0x00000001 - routine was entered 494 // 0x00000010 - routine return false at end 495 // 0x00000100 - thread exited (return false) 496 // 0x00000200 - suspend request cancelled (return false) 497 // 0x00000400 - thread suspended (return true) 498 // 0x00001000 - thread is in a suspend equivalent state (return true) 499 // 0x00002000 - thread is native and walkable (return true) 500 // 0x00004000 - thread is native_trans and walkable (needed retry) 501 // 502 // set in wait_for_ext_suspend_completion(): 503 // 0x00010000 - routine was entered 504 // 0x00020000 - suspend request cancelled before loop (return false) 505 // 0x00040000 - thread suspended before loop (return true) 506 // 0x00080000 - suspend request cancelled in loop (return false) 507 // 0x00100000 - thread suspended in loop (return true) 508 // 0x00200000 - suspend not completed during retry loop (return false) 509 510 // Helper class for tracing suspend wait debug bits. 511 // 512 // 0x00000100 indicates that the target thread exited before it could 513 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 514 // 0x00080000 each indicate a cancelled suspend request so they don't 515 // count as wait failures either. 516 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 517 518 class TraceSuspendDebugBits : public StackObj { 519 private: 520 JavaThread * jt; 521 bool is_wait; 522 bool called_by_wait; // meaningful when !is_wait 523 uint32_t * bits; 524 525 public: 526 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 527 uint32_t *_bits) { 528 jt = _jt; 529 is_wait = _is_wait; 530 called_by_wait = _called_by_wait; 531 bits = _bits; 532 } 533 534 ~TraceSuspendDebugBits() { 535 if (!is_wait) { 536 #if 1 537 // By default, don't trace bits for is_ext_suspend_completed() calls. 538 // That trace is very chatty. 539 return; 540 #else 541 if (!called_by_wait) { 542 // If tracing for is_ext_suspend_completed() is enabled, then only 543 // trace calls to it from wait_for_ext_suspend_completion() 544 return; 545 } 546 #endif 547 } 548 549 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 550 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 551 MutexLocker ml(Threads_lock); // needed for get_thread_name() 552 ResourceMark rm; 553 554 tty->print_cr( 555 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 556 jt->get_thread_name(), *bits); 557 558 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 559 } 560 } 561 } 562 }; 563 #undef DEBUG_FALSE_BITS 564 565 566 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 567 uint32_t *bits) { 568 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 569 570 bool did_trans_retry = false; // only do thread_in_native_trans retry once 571 bool do_trans_retry; // flag to force the retry 572 573 *bits |= 0x00000001; 574 575 do { 576 do_trans_retry = false; 577 578 if (is_exiting()) { 579 // Thread is in the process of exiting. This is always checked 580 // first to reduce the risk of dereferencing a freed JavaThread. 581 *bits |= 0x00000100; 582 return false; 583 } 584 585 if (!is_external_suspend()) { 586 // Suspend request is cancelled. This is always checked before 587 // is_ext_suspended() to reduce the risk of a rogue resume 588 // confusing the thread that made the suspend request. 589 *bits |= 0x00000200; 590 return false; 591 } 592 593 if (is_ext_suspended()) { 594 // thread is suspended 595 *bits |= 0x00000400; 596 return true; 597 } 598 599 // Now that we no longer do hard suspends of threads running 600 // native code, the target thread can be changing thread state 601 // while we are in this routine: 602 // 603 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 604 // 605 // We save a copy of the thread state as observed at this moment 606 // and make our decision about suspend completeness based on the 607 // copy. This closes the race where the thread state is seen as 608 // _thread_in_native_trans in the if-thread_blocked check, but is 609 // seen as _thread_blocked in if-thread_in_native_trans check. 610 JavaThreadState save_state = thread_state(); 611 612 if (save_state == _thread_blocked && is_suspend_equivalent()) { 613 // If the thread's state is _thread_blocked and this blocking 614 // condition is known to be equivalent to a suspend, then we can 615 // consider the thread to be externally suspended. This means that 616 // the code that sets _thread_blocked has been modified to do 617 // self-suspension if the blocking condition releases. We also 618 // used to check for CONDVAR_WAIT here, but that is now covered by 619 // the _thread_blocked with self-suspension check. 620 // 621 // Return true since we wouldn't be here unless there was still an 622 // external suspend request. 623 *bits |= 0x00001000; 624 return true; 625 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 626 // Threads running native code will self-suspend on native==>VM/Java 627 // transitions. If its stack is walkable (should always be the case 628 // unless this function is called before the actual java_suspend() 629 // call), then the wait is done. 630 *bits |= 0x00002000; 631 return true; 632 } else if (!called_by_wait && !did_trans_retry && 633 save_state == _thread_in_native_trans && 634 frame_anchor()->walkable()) { 635 // The thread is transitioning from thread_in_native to another 636 // thread state. check_safepoint_and_suspend_for_native_trans() 637 // will force the thread to self-suspend. If it hasn't gotten 638 // there yet we may have caught the thread in-between the native 639 // code check above and the self-suspend. Lucky us. If we were 640 // called by wait_for_ext_suspend_completion(), then it 641 // will be doing the retries so we don't have to. 642 // 643 // Since we use the saved thread state in the if-statement above, 644 // there is a chance that the thread has already transitioned to 645 // _thread_blocked by the time we get here. In that case, we will 646 // make a single unnecessary pass through the logic below. This 647 // doesn't hurt anything since we still do the trans retry. 648 649 *bits |= 0x00004000; 650 651 // Once the thread leaves thread_in_native_trans for another 652 // thread state, we break out of this retry loop. We shouldn't 653 // need this flag to prevent us from getting back here, but 654 // sometimes paranoia is good. 655 did_trans_retry = true; 656 657 // We wait for the thread to transition to a more usable state. 658 for (int i = 1; i <= SuspendRetryCount; i++) { 659 // We used to do an "os::yield_all(i)" call here with the intention 660 // that yielding would increase on each retry. However, the parameter 661 // is ignored on Linux which means the yield didn't scale up. Waiting 662 // on the SR_lock below provides a much more predictable scale up for 663 // the delay. It also provides a simple/direct point to check for any 664 // safepoint requests from the VMThread 665 666 // temporarily drops SR_lock while doing wait with safepoint check 667 // (if we're a JavaThread - the WatcherThread can also call this) 668 // and increase delay with each retry 669 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 670 671 // check the actual thread state instead of what we saved above 672 if (thread_state() != _thread_in_native_trans) { 673 // the thread has transitioned to another thread state so 674 // try all the checks (except this one) one more time. 675 do_trans_retry = true; 676 break; 677 } 678 } // end retry loop 679 680 681 } 682 } while (do_trans_retry); 683 684 *bits |= 0x00000010; 685 return false; 686 } 687 688 // Wait for an external suspend request to complete (or be cancelled). 689 // Returns true if the thread is externally suspended and false otherwise. 690 // 691 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 692 uint32_t *bits) { 693 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 694 false /* !called_by_wait */, bits); 695 696 // local flag copies to minimize SR_lock hold time 697 bool is_suspended; 698 bool pending; 699 uint32_t reset_bits; 700 701 // set a marker so is_ext_suspend_completed() knows we are the caller 702 *bits |= 0x00010000; 703 704 // We use reset_bits to reinitialize the bits value at the top of 705 // each retry loop. This allows the caller to make use of any 706 // unused bits for their own marking purposes. 707 reset_bits = *bits; 708 709 { 710 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 711 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 712 delay, bits); 713 pending = is_external_suspend(); 714 } 715 // must release SR_lock to allow suspension to complete 716 717 if (!pending) { 718 // A cancelled suspend request is the only false return from 719 // is_ext_suspend_completed() that keeps us from entering the 720 // retry loop. 721 *bits |= 0x00020000; 722 return false; 723 } 724 725 if (is_suspended) { 726 *bits |= 0x00040000; 727 return true; 728 } 729 730 for (int i = 1; i <= retries; i++) { 731 *bits = reset_bits; // reinit to only track last retry 732 733 // We used to do an "os::yield_all(i)" call here with the intention 734 // that yielding would increase on each retry. However, the parameter 735 // is ignored on Linux which means the yield didn't scale up. Waiting 736 // on the SR_lock below provides a much more predictable scale up for 737 // the delay. It also provides a simple/direct point to check for any 738 // safepoint requests from the VMThread 739 740 { 741 MutexLocker ml(SR_lock()); 742 // wait with safepoint check (if we're a JavaThread - the WatcherThread 743 // can also call this) and increase delay with each retry 744 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 745 746 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 747 delay, bits); 748 749 // It is possible for the external suspend request to be cancelled 750 // (by a resume) before the actual suspend operation is completed. 751 // Refresh our local copy to see if we still need to wait. 752 pending = is_external_suspend(); 753 } 754 755 if (!pending) { 756 // A cancelled suspend request is the only false return from 757 // is_ext_suspend_completed() that keeps us from staying in the 758 // retry loop. 759 *bits |= 0x00080000; 760 return false; 761 } 762 763 if (is_suspended) { 764 *bits |= 0x00100000; 765 return true; 766 } 767 } // end retry loop 768 769 // thread did not suspend after all our retries 770 *bits |= 0x00200000; 771 return false; 772 } 773 774 // Called from API entry points which perform stack walking. If the 775 // associated JavaThread is the current thread, then wait_for_suspend 776 // is not used. Otherwise, it determines if we should wait for the 777 // "other" thread to complete external suspension. (NOTE: in future 778 // releases the suspension mechanism should be reimplemented so this 779 // is not necessary.) 780 // 781 bool 782 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 783 if (this != JavaThread::current()) { 784 // "other" threads require special handling. 785 if (wait_for_suspend) { 786 // We are allowed to wait for the external suspend to complete 787 // so give the other thread a chance to get suspended. 788 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 789 SuspendRetryDelay, bits)) { 790 // Didn't make it so let the caller know. 791 return false; 792 } 793 } 794 // We aren't allowed to wait for the external suspend to complete 795 // so if the other thread isn't externally suspended we need to 796 // let the caller know. 797 else if (!is_ext_suspend_completed_with_lock(bits)) { 798 return false; 799 } 800 } 801 802 return true; 803 } 804 805 #ifndef PRODUCT 806 void JavaThread::record_jump(address target, address instr, const char* file, 807 int line) { 808 809 // This should not need to be atomic as the only way for simultaneous 810 // updates is via interrupts. Even then this should be rare or non-existent 811 // and we don't care that much anyway. 812 813 int index = _jmp_ring_index; 814 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 815 _jmp_ring[index]._target = (intptr_t) target; 816 _jmp_ring[index]._instruction = (intptr_t) instr; 817 _jmp_ring[index]._file = file; 818 _jmp_ring[index]._line = line; 819 } 820 #endif // PRODUCT 821 822 void Thread::interrupt(Thread* thread) { 823 debug_only(check_for_dangling_thread_pointer(thread);) 824 os::interrupt(thread); 825 } 826 827 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 828 debug_only(check_for_dangling_thread_pointer(thread);) 829 // Note: If clear_interrupted==false, this simply fetches and 830 // returns the value of the field osthread()->interrupted(). 831 return os::is_interrupted(thread, clear_interrupted); 832 } 833 834 835 // GC Support 836 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 837 int thread_parity = _oops_do_parity; 838 if (thread_parity != strong_roots_parity) { 839 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 840 if (res == thread_parity) { 841 return true; 842 } else { 843 guarantee(res == strong_roots_parity, "Or else what?"); 844 return false; 845 } 846 } 847 return false; 848 } 849 850 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 851 active_handles()->oops_do(f); 852 // Do oop for ThreadShadow 853 f->do_oop((oop*)&_pending_exception); 854 handle_area()->oops_do(f); 855 856 if (MonitorInUseLists) { 857 // When using thread local monitor lists, we scan them here, 858 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 859 ObjectSynchronizer::thread_local_used_oops_do(this, f); 860 } 861 } 862 863 void Thread::metadata_handles_do(void f(Metadata*)) { 864 // Only walk the Handles in Thread. 865 if (metadata_handles() != NULL) { 866 for (int i = 0; i< metadata_handles()->length(); i++) { 867 f(metadata_handles()->at(i)); 868 } 869 } 870 } 871 872 void Thread::print_on(outputStream* st) const { 873 // get_priority assumes osthread initialized 874 if (osthread() != NULL) { 875 int os_prio; 876 if (os::get_native_priority(this, &os_prio) == OS_OK) { 877 st->print("os_prio=%d ", os_prio); 878 } 879 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 880 osthread()->print_on(st); 881 } 882 ThreadsSMRSupport::print_info_on(this, st); 883 st->print(" "); 884 debug_only(if (WizardMode) print_owned_locks_on(st);) 885 } 886 887 // Thread::print_on_error() is called by fatal error handler. Don't use 888 // any lock or allocate memory. 889 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 890 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 891 892 if (is_VM_thread()) { st->print("VMThread"); } 893 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 894 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 895 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 896 else { st->print("Thread"); } 897 898 if (is_Named_thread()) { 899 st->print(" \"%s\"", name()); 900 } 901 902 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 903 p2i(stack_end()), p2i(stack_base())); 904 905 if (osthread()) { 906 st->print(" [id=%d]", osthread()->thread_id()); 907 } 908 909 ThreadsSMRSupport::print_info_on(this, st); 910 } 911 912 void Thread::print_value_on(outputStream* st) const { 913 if (is_Named_thread()) { 914 st->print(" \"%s\" ", name()); 915 } 916 st->print(INTPTR_FORMAT, p2i(this)); // print address 917 } 918 919 #ifdef ASSERT 920 void Thread::print_owned_locks_on(outputStream* st) const { 921 Monitor *cur = _owned_locks; 922 if (cur == NULL) { 923 st->print(" (no locks) "); 924 } else { 925 st->print_cr(" Locks owned:"); 926 while (cur) { 927 cur->print_on(st); 928 cur = cur->next(); 929 } 930 } 931 } 932 933 static int ref_use_count = 0; 934 935 bool Thread::owns_locks_but_compiled_lock() const { 936 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 937 if (cur != Compile_lock) return true; 938 } 939 return false; 940 } 941 942 943 #endif 944 945 #ifndef PRODUCT 946 947 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 948 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 949 // no threads which allow_vm_block's are held 950 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 951 // Check if current thread is allowed to block at a safepoint 952 if (!(_allow_safepoint_count == 0)) { 953 fatal("Possible safepoint reached by thread that does not allow it"); 954 } 955 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 956 fatal("LEAF method calling lock?"); 957 } 958 959 #ifdef ASSERT 960 if (potential_vm_operation && is_Java_thread() 961 && !Universe::is_bootstrapping()) { 962 // Make sure we do not hold any locks that the VM thread also uses. 963 // This could potentially lead to deadlocks 964 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 965 // Threads_lock is special, since the safepoint synchronization will not start before this is 966 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 967 // since it is used to transfer control between JavaThreads and the VMThread 968 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 969 if ((cur->allow_vm_block() && 970 cur != Threads_lock && 971 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 972 cur != VMOperationRequest_lock && 973 cur != VMOperationQueue_lock) || 974 cur->rank() == Mutex::special) { 975 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 976 } 977 } 978 } 979 980 if (GCALotAtAllSafepoints) { 981 // We could enter a safepoint here and thus have a gc 982 InterfaceSupport::check_gc_alot(); 983 } 984 #endif 985 } 986 #endif 987 988 bool Thread::is_in_stack(address adr) const { 989 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 990 address end = os::current_stack_pointer(); 991 // Allow non Java threads to call this without stack_base 992 if (_stack_base == NULL) return true; 993 if (stack_base() >= adr && adr >= end) return true; 994 995 return false; 996 } 997 998 bool Thread::is_in_usable_stack(address adr) const { 999 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1000 size_t usable_stack_size = _stack_size - stack_guard_size; 1001 1002 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1003 } 1004 1005 1006 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1007 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1008 // used for compilation in the future. If that change is made, the need for these methods 1009 // should be revisited, and they should be removed if possible. 1010 1011 bool Thread::is_lock_owned(address adr) const { 1012 return on_local_stack(adr); 1013 } 1014 1015 bool Thread::set_as_starting_thread() { 1016 // NOTE: this must be called inside the main thread. 1017 return os::create_main_thread((JavaThread*)this); 1018 } 1019 1020 static void initialize_class(Symbol* class_name, TRAPS) { 1021 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1022 InstanceKlass::cast(klass)->initialize(CHECK); 1023 } 1024 1025 1026 // Creates the initial ThreadGroup 1027 static Handle create_initial_thread_group(TRAPS) { 1028 Handle system_instance = JavaCalls::construct_new_instance( 1029 SystemDictionary::ThreadGroup_klass(), 1030 vmSymbols::void_method_signature(), 1031 CHECK_NH); 1032 Universe::set_system_thread_group(system_instance()); 1033 1034 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1035 Handle main_instance = JavaCalls::construct_new_instance( 1036 SystemDictionary::ThreadGroup_klass(), 1037 vmSymbols::threadgroup_string_void_signature(), 1038 system_instance, 1039 string, 1040 CHECK_NH); 1041 return main_instance; 1042 } 1043 1044 // Creates the initial Thread 1045 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1046 TRAPS) { 1047 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1048 assert(ik->is_initialized(), "must be"); 1049 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1050 1051 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1052 // constructor calls Thread.current(), which must be set here for the 1053 // initial thread. 1054 java_lang_Thread::set_thread(thread_oop(), thread); 1055 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1056 thread->set_threadObj(thread_oop()); 1057 1058 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1059 1060 JavaValue result(T_VOID); 1061 JavaCalls::call_special(&result, thread_oop, 1062 ik, 1063 vmSymbols::object_initializer_name(), 1064 vmSymbols::threadgroup_string_void_signature(), 1065 thread_group, 1066 string, 1067 CHECK_NULL); 1068 return thread_oop(); 1069 } 1070 1071 char java_runtime_name[128] = ""; 1072 char java_runtime_version[128] = ""; 1073 1074 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1075 static const char* get_java_runtime_name(TRAPS) { 1076 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1077 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1078 fieldDescriptor fd; 1079 bool found = k != NULL && 1080 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1081 vmSymbols::string_signature(), &fd); 1082 if (found) { 1083 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1084 if (name_oop == NULL) { 1085 return NULL; 1086 } 1087 const char* name = java_lang_String::as_utf8_string(name_oop, 1088 java_runtime_name, 1089 sizeof(java_runtime_name)); 1090 return name; 1091 } else { 1092 return NULL; 1093 } 1094 } 1095 1096 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1097 static const char* get_java_runtime_version(TRAPS) { 1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1100 fieldDescriptor fd; 1101 bool found = k != NULL && 1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1103 vmSymbols::string_signature(), &fd); 1104 if (found) { 1105 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1106 if (name_oop == NULL) { 1107 return NULL; 1108 } 1109 const char* name = java_lang_String::as_utf8_string(name_oop, 1110 java_runtime_version, 1111 sizeof(java_runtime_version)); 1112 return name; 1113 } else { 1114 return NULL; 1115 } 1116 } 1117 1118 // General purpose hook into Java code, run once when the VM is initialized. 1119 // The Java library method itself may be changed independently from the VM. 1120 static void call_postVMInitHook(TRAPS) { 1121 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1122 if (klass != NULL) { 1123 JavaValue result(T_VOID); 1124 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1125 vmSymbols::void_method_signature(), 1126 CHECK); 1127 } 1128 } 1129 1130 static void reset_vm_info_property(TRAPS) { 1131 // the vm info string 1132 ResourceMark rm(THREAD); 1133 const char *vm_info = VM_Version::vm_info_string(); 1134 1135 // java.lang.System class 1136 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1137 1138 // setProperty arguments 1139 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1140 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1141 1142 // return value 1143 JavaValue r(T_OBJECT); 1144 1145 // public static String setProperty(String key, String value); 1146 JavaCalls::call_static(&r, 1147 klass, 1148 vmSymbols::setProperty_name(), 1149 vmSymbols::string_string_string_signature(), 1150 key_str, 1151 value_str, 1152 CHECK); 1153 } 1154 1155 1156 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1157 bool daemon, TRAPS) { 1158 assert(thread_group.not_null(), "thread group should be specified"); 1159 assert(threadObj() == NULL, "should only create Java thread object once"); 1160 1161 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1162 assert(ik->is_initialized(), "must be"); 1163 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1164 1165 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1166 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1167 // constructor calls Thread.current(), which must be set here. 1168 java_lang_Thread::set_thread(thread_oop(), this); 1169 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1170 set_threadObj(thread_oop()); 1171 1172 JavaValue result(T_VOID); 1173 if (thread_name != NULL) { 1174 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1175 // Thread gets assigned specified name and null target 1176 JavaCalls::call_special(&result, 1177 thread_oop, 1178 ik, 1179 vmSymbols::object_initializer_name(), 1180 vmSymbols::threadgroup_string_void_signature(), 1181 thread_group, 1182 name, 1183 THREAD); 1184 } else { 1185 // Thread gets assigned name "Thread-nnn" and null target 1186 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1187 JavaCalls::call_special(&result, 1188 thread_oop, 1189 ik, 1190 vmSymbols::object_initializer_name(), 1191 vmSymbols::threadgroup_runnable_void_signature(), 1192 thread_group, 1193 Handle(), 1194 THREAD); 1195 } 1196 1197 1198 if (daemon) { 1199 java_lang_Thread::set_daemon(thread_oop()); 1200 } 1201 1202 if (HAS_PENDING_EXCEPTION) { 1203 return; 1204 } 1205 1206 Klass* group = SystemDictionary::ThreadGroup_klass(); 1207 Handle threadObj(THREAD, this->threadObj()); 1208 1209 JavaCalls::call_special(&result, 1210 thread_group, 1211 group, 1212 vmSymbols::add_method_name(), 1213 vmSymbols::thread_void_signature(), 1214 threadObj, // Arg 1 1215 THREAD); 1216 } 1217 1218 // NamedThread -- non-JavaThread subclasses with multiple 1219 // uniquely named instances should derive from this. 1220 NamedThread::NamedThread() : Thread() { 1221 _name = NULL; 1222 _processed_thread = NULL; 1223 _gc_id = GCId::undefined(); 1224 } 1225 1226 NamedThread::~NamedThread() { 1227 if (_name != NULL) { 1228 FREE_C_HEAP_ARRAY(char, _name); 1229 _name = NULL; 1230 } 1231 } 1232 1233 void NamedThread::set_name(const char* format, ...) { 1234 guarantee(_name == NULL, "Only get to set name once."); 1235 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1236 guarantee(_name != NULL, "alloc failure"); 1237 va_list ap; 1238 va_start(ap, format); 1239 jio_vsnprintf(_name, max_name_len, format, ap); 1240 va_end(ap); 1241 } 1242 1243 void NamedThread::initialize_named_thread() { 1244 set_native_thread_name(name()); 1245 } 1246 1247 void NamedThread::print_on(outputStream* st) const { 1248 st->print("\"%s\" ", name()); 1249 Thread::print_on(st); 1250 st->cr(); 1251 } 1252 1253 1254 // ======= WatcherThread ======== 1255 1256 // The watcher thread exists to simulate timer interrupts. It should 1257 // be replaced by an abstraction over whatever native support for 1258 // timer interrupts exists on the platform. 1259 1260 WatcherThread* WatcherThread::_watcher_thread = NULL; 1261 bool WatcherThread::_startable = false; 1262 volatile bool WatcherThread::_should_terminate = false; 1263 1264 WatcherThread::WatcherThread() : Thread() { 1265 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1266 if (os::create_thread(this, os::watcher_thread)) { 1267 _watcher_thread = this; 1268 1269 // Set the watcher thread to the highest OS priority which should not be 1270 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1271 // is created. The only normal thread using this priority is the reference 1272 // handler thread, which runs for very short intervals only. 1273 // If the VMThread's priority is not lower than the WatcherThread profiling 1274 // will be inaccurate. 1275 os::set_priority(this, MaxPriority); 1276 if (!DisableStartThread) { 1277 os::start_thread(this); 1278 } 1279 } 1280 } 1281 1282 int WatcherThread::sleep() const { 1283 // The WatcherThread does not participate in the safepoint protocol 1284 // for the PeriodicTask_lock because it is not a JavaThread. 1285 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1286 1287 if (_should_terminate) { 1288 // check for termination before we do any housekeeping or wait 1289 return 0; // we did not sleep. 1290 } 1291 1292 // remaining will be zero if there are no tasks, 1293 // causing the WatcherThread to sleep until a task is 1294 // enrolled 1295 int remaining = PeriodicTask::time_to_wait(); 1296 int time_slept = 0; 1297 1298 // we expect this to timeout - we only ever get unparked when 1299 // we should terminate or when a new task has been enrolled 1300 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1301 1302 jlong time_before_loop = os::javaTimeNanos(); 1303 1304 while (true) { 1305 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1306 remaining); 1307 jlong now = os::javaTimeNanos(); 1308 1309 if (remaining == 0) { 1310 // if we didn't have any tasks we could have waited for a long time 1311 // consider the time_slept zero and reset time_before_loop 1312 time_slept = 0; 1313 time_before_loop = now; 1314 } else { 1315 // need to recalculate since we might have new tasks in _tasks 1316 time_slept = (int) ((now - time_before_loop) / 1000000); 1317 } 1318 1319 // Change to task list or spurious wakeup of some kind 1320 if (timedout || _should_terminate) { 1321 break; 1322 } 1323 1324 remaining = PeriodicTask::time_to_wait(); 1325 if (remaining == 0) { 1326 // Last task was just disenrolled so loop around and wait until 1327 // another task gets enrolled 1328 continue; 1329 } 1330 1331 remaining -= time_slept; 1332 if (remaining <= 0) { 1333 break; 1334 } 1335 } 1336 1337 return time_slept; 1338 } 1339 1340 void WatcherThread::run() { 1341 assert(this == watcher_thread(), "just checking"); 1342 1343 this->record_stack_base_and_size(); 1344 this->set_native_thread_name(this->name()); 1345 this->set_active_handles(JNIHandleBlock::allocate_block()); 1346 while (true) { 1347 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1348 assert(watcher_thread() == this, "thread consistency check"); 1349 1350 // Calculate how long it'll be until the next PeriodicTask work 1351 // should be done, and sleep that amount of time. 1352 int time_waited = sleep(); 1353 1354 if (VMError::is_error_reported()) { 1355 // A fatal error has happened, the error handler(VMError::report_and_die) 1356 // should abort JVM after creating an error log file. However in some 1357 // rare cases, the error handler itself might deadlock. Here periodically 1358 // check for error reporting timeouts, and if it happens, just proceed to 1359 // abort the VM. 1360 1361 // This code is in WatcherThread because WatcherThread wakes up 1362 // periodically so the fatal error handler doesn't need to do anything; 1363 // also because the WatcherThread is less likely to crash than other 1364 // threads. 1365 1366 for (;;) { 1367 // Note: we use naked sleep in this loop because we want to avoid using 1368 // any kind of VM infrastructure which may be broken at this point. 1369 if (VMError::check_timeout()) { 1370 // We hit error reporting timeout. Error reporting was interrupted and 1371 // will be wrapping things up now (closing files etc). Give it some more 1372 // time, then quit the VM. 1373 os::naked_short_sleep(200); 1374 // Print a message to stderr. 1375 fdStream err(defaultStream::output_fd()); 1376 err.print_raw_cr("# [ timer expired, abort... ]"); 1377 // skip atexit/vm_exit/vm_abort hooks 1378 os::die(); 1379 } 1380 1381 // Wait a second, then recheck for timeout. 1382 os::naked_short_sleep(999); 1383 } 1384 } 1385 1386 if (_should_terminate) { 1387 // check for termination before posting the next tick 1388 break; 1389 } 1390 1391 PeriodicTask::real_time_tick(time_waited); 1392 } 1393 1394 // Signal that it is terminated 1395 { 1396 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1397 _watcher_thread = NULL; 1398 Terminator_lock->notify(); 1399 } 1400 } 1401 1402 void WatcherThread::start() { 1403 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1404 1405 if (watcher_thread() == NULL && _startable) { 1406 _should_terminate = false; 1407 // Create the single instance of WatcherThread 1408 new WatcherThread(); 1409 } 1410 } 1411 1412 void WatcherThread::make_startable() { 1413 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1414 _startable = true; 1415 } 1416 1417 void WatcherThread::stop() { 1418 { 1419 // Follow normal safepoint aware lock enter protocol since the 1420 // WatcherThread is stopped by another JavaThread. 1421 MutexLocker ml(PeriodicTask_lock); 1422 _should_terminate = true; 1423 1424 WatcherThread* watcher = watcher_thread(); 1425 if (watcher != NULL) { 1426 // unpark the WatcherThread so it can see that it should terminate 1427 watcher->unpark(); 1428 } 1429 } 1430 1431 MutexLocker mu(Terminator_lock); 1432 1433 while (watcher_thread() != NULL) { 1434 // This wait should make safepoint checks, wait without a timeout, 1435 // and wait as a suspend-equivalent condition. 1436 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1437 Mutex::_as_suspend_equivalent_flag); 1438 } 1439 } 1440 1441 void WatcherThread::unpark() { 1442 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1443 PeriodicTask_lock->notify(); 1444 } 1445 1446 void WatcherThread::print_on(outputStream* st) const { 1447 st->print("\"%s\" ", name()); 1448 Thread::print_on(st); 1449 st->cr(); 1450 } 1451 1452 // ======= JavaThread ======== 1453 1454 #if INCLUDE_JVMCI 1455 1456 jlong* JavaThread::_jvmci_old_thread_counters; 1457 1458 bool jvmci_counters_include(JavaThread* thread) { 1459 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1460 } 1461 1462 void JavaThread::collect_counters(typeArrayOop array) { 1463 if (JVMCICounterSize > 0) { 1464 JavaThreadIteratorWithHandle jtiwh; 1465 for (int i = 0; i < array->length(); i++) { 1466 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1467 } 1468 for (; JavaThread *tp = jtiwh.next(); ) { 1469 if (jvmci_counters_include(tp)) { 1470 for (int i = 0; i < array->length(); i++) { 1471 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1472 } 1473 } 1474 } 1475 } 1476 } 1477 1478 #endif // INCLUDE_JVMCI 1479 1480 // A JavaThread is a normal Java thread 1481 1482 void JavaThread::initialize() { 1483 // Initialize fields 1484 1485 set_saved_exception_pc(NULL); 1486 set_threadObj(NULL); 1487 _anchor.clear(); 1488 set_entry_point(NULL); 1489 set_jni_functions(jni_functions()); 1490 set_callee_target(NULL); 1491 set_vm_result(NULL); 1492 set_vm_result_2(NULL); 1493 set_vframe_array_head(NULL); 1494 set_vframe_array_last(NULL); 1495 set_deferred_locals(NULL); 1496 set_deopt_mark(NULL); 1497 set_deopt_compiled_method(NULL); 1498 clear_must_deopt_id(); 1499 set_monitor_chunks(NULL); 1500 set_next(NULL); 1501 _on_thread_list = false; 1502 set_thread_state(_thread_new); 1503 _terminated = _not_terminated; 1504 _privileged_stack_top = NULL; 1505 _array_for_gc = NULL; 1506 _suspend_equivalent = false; 1507 _in_deopt_handler = 0; 1508 _doing_unsafe_access = false; 1509 _stack_guard_state = stack_guard_unused; 1510 #if INCLUDE_JVMCI 1511 _pending_monitorenter = false; 1512 _pending_deoptimization = -1; 1513 _pending_failed_speculation = NULL; 1514 _pending_transfer_to_interpreter = false; 1515 _adjusting_comp_level = false; 1516 _jvmci._alternate_call_target = NULL; 1517 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1518 if (JVMCICounterSize > 0) { 1519 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1520 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1521 } else { 1522 _jvmci_counters = NULL; 1523 } 1524 #endif // INCLUDE_JVMCI 1525 _reserved_stack_activation = NULL; // stack base not known yet 1526 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1527 _exception_pc = 0; 1528 _exception_handler_pc = 0; 1529 _is_method_handle_return = 0; 1530 _jvmti_thread_state= NULL; 1531 _should_post_on_exceptions_flag = JNI_FALSE; 1532 _jvmti_get_loaded_classes_closure = NULL; 1533 _interp_only_mode = 0; 1534 _special_runtime_exit_condition = _no_async_condition; 1535 _pending_async_exception = NULL; 1536 _thread_stat = NULL; 1537 _thread_stat = new ThreadStatistics(); 1538 _blocked_on_compilation = false; 1539 _jni_active_critical = 0; 1540 _pending_jni_exception_check_fn = NULL; 1541 _do_not_unlock_if_synchronized = false; 1542 _cached_monitor_info = NULL; 1543 _parker = Parker::Allocate(this); 1544 1545 #ifndef PRODUCT 1546 _jmp_ring_index = 0; 1547 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1548 record_jump(NULL, NULL, NULL, 0); 1549 } 1550 #endif // PRODUCT 1551 1552 // Setup safepoint state info for this thread 1553 ThreadSafepointState::create(this); 1554 1555 debug_only(_java_call_counter = 0); 1556 1557 // JVMTI PopFrame support 1558 _popframe_condition = popframe_inactive; 1559 _popframe_preserved_args = NULL; 1560 _popframe_preserved_args_size = 0; 1561 _frames_to_pop_failed_realloc = 0; 1562 1563 if (SafepointMechanism::uses_thread_local_poll()) { 1564 SafepointMechanism::initialize_header(this); 1565 } 1566 1567 pd_initialize(); 1568 } 1569 1570 JavaThread::JavaThread(bool is_attaching_via_jni) : 1571 Thread() { 1572 initialize(); 1573 if (is_attaching_via_jni) { 1574 _jni_attach_state = _attaching_via_jni; 1575 } else { 1576 _jni_attach_state = _not_attaching_via_jni; 1577 } 1578 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1579 } 1580 1581 bool JavaThread::reguard_stack(address cur_sp) { 1582 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1583 && _stack_guard_state != stack_guard_reserved_disabled) { 1584 return true; // Stack already guarded or guard pages not needed. 1585 } 1586 1587 if (register_stack_overflow()) { 1588 // For those architectures which have separate register and 1589 // memory stacks, we must check the register stack to see if 1590 // it has overflowed. 1591 return false; 1592 } 1593 1594 // Java code never executes within the yellow zone: the latter is only 1595 // there to provoke an exception during stack banging. If java code 1596 // is executing there, either StackShadowPages should be larger, or 1597 // some exception code in c1, c2 or the interpreter isn't unwinding 1598 // when it should. 1599 guarantee(cur_sp > stack_reserved_zone_base(), 1600 "not enough space to reguard - increase StackShadowPages"); 1601 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1602 enable_stack_yellow_reserved_zone(); 1603 if (reserved_stack_activation() != stack_base()) { 1604 set_reserved_stack_activation(stack_base()); 1605 } 1606 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1607 set_reserved_stack_activation(stack_base()); 1608 enable_stack_reserved_zone(); 1609 } 1610 return true; 1611 } 1612 1613 bool JavaThread::reguard_stack(void) { 1614 return reguard_stack(os::current_stack_pointer()); 1615 } 1616 1617 1618 void JavaThread::block_if_vm_exited() { 1619 if (_terminated == _vm_exited) { 1620 // _vm_exited is set at safepoint, and Threads_lock is never released 1621 // we will block here forever 1622 Threads_lock->lock_without_safepoint_check(); 1623 ShouldNotReachHere(); 1624 } 1625 } 1626 1627 1628 // Remove this ifdef when C1 is ported to the compiler interface. 1629 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1630 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1631 1632 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1633 Thread() { 1634 initialize(); 1635 _jni_attach_state = _not_attaching_via_jni; 1636 set_entry_point(entry_point); 1637 // Create the native thread itself. 1638 // %note runtime_23 1639 os::ThreadType thr_type = os::java_thread; 1640 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1641 os::java_thread; 1642 os::create_thread(this, thr_type, stack_sz); 1643 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1644 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1645 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1646 // the exception consists of creating the exception object & initializing it, initialization 1647 // will leave the VM via a JavaCall and then all locks must be unlocked). 1648 // 1649 // The thread is still suspended when we reach here. Thread must be explicit started 1650 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1651 // by calling Threads:add. The reason why this is not done here, is because the thread 1652 // object must be fully initialized (take a look at JVM_Start) 1653 } 1654 1655 JavaThread::~JavaThread() { 1656 1657 // JSR166 -- return the parker to the free list 1658 Parker::Release(_parker); 1659 _parker = NULL; 1660 1661 // Free any remaining previous UnrollBlock 1662 vframeArray* old_array = vframe_array_last(); 1663 1664 if (old_array != NULL) { 1665 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1666 old_array->set_unroll_block(NULL); 1667 delete old_info; 1668 delete old_array; 1669 } 1670 1671 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1672 if (deferred != NULL) { 1673 // This can only happen if thread is destroyed before deoptimization occurs. 1674 assert(deferred->length() != 0, "empty array!"); 1675 do { 1676 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1677 deferred->remove_at(0); 1678 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1679 delete dlv; 1680 } while (deferred->length() != 0); 1681 delete deferred; 1682 } 1683 1684 // All Java related clean up happens in exit 1685 ThreadSafepointState::destroy(this); 1686 if (_thread_stat != NULL) delete _thread_stat; 1687 1688 #if INCLUDE_JVMCI 1689 if (JVMCICounterSize > 0) { 1690 if (jvmci_counters_include(this)) { 1691 for (int i = 0; i < JVMCICounterSize; i++) { 1692 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1693 } 1694 } 1695 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1696 } 1697 #endif // INCLUDE_JVMCI 1698 } 1699 1700 1701 // The first routine called by a new Java thread 1702 void JavaThread::run() { 1703 // initialize thread-local alloc buffer related fields 1704 this->initialize_tlab(); 1705 1706 // used to test validity of stack trace backs 1707 this->record_base_of_stack_pointer(); 1708 1709 // Record real stack base and size. 1710 this->record_stack_base_and_size(); 1711 1712 this->create_stack_guard_pages(); 1713 1714 this->cache_global_variables(); 1715 1716 // Thread is now sufficient initialized to be handled by the safepoint code as being 1717 // in the VM. Change thread state from _thread_new to _thread_in_vm 1718 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1719 1720 assert(JavaThread::current() == this, "sanity check"); 1721 assert(!Thread::current()->owns_locks(), "sanity check"); 1722 1723 DTRACE_THREAD_PROBE(start, this); 1724 1725 // This operation might block. We call that after all safepoint checks for a new thread has 1726 // been completed. 1727 this->set_active_handles(JNIHandleBlock::allocate_block()); 1728 1729 if (JvmtiExport::should_post_thread_life()) { 1730 JvmtiExport::post_thread_start(this); 1731 } 1732 1733 EventThreadStart event; 1734 if (event.should_commit()) { 1735 event.set_thread(JFR_THREAD_ID(this)); 1736 event.commit(); 1737 } 1738 1739 // We call another function to do the rest so we are sure that the stack addresses used 1740 // from there will be lower than the stack base just computed 1741 thread_main_inner(); 1742 1743 // Note, thread is no longer valid at this point! 1744 } 1745 1746 1747 void JavaThread::thread_main_inner() { 1748 assert(JavaThread::current() == this, "sanity check"); 1749 assert(this->threadObj() != NULL, "just checking"); 1750 1751 // Execute thread entry point unless this thread has a pending exception 1752 // or has been stopped before starting. 1753 // Note: Due to JVM_StopThread we can have pending exceptions already! 1754 if (!this->has_pending_exception() && 1755 !java_lang_Thread::is_stillborn(this->threadObj())) { 1756 { 1757 ResourceMark rm(this); 1758 this->set_native_thread_name(this->get_thread_name()); 1759 } 1760 HandleMark hm(this); 1761 this->entry_point()(this, this); 1762 } 1763 1764 DTRACE_THREAD_PROBE(stop, this); 1765 1766 this->exit(false); 1767 this->smr_delete(); 1768 } 1769 1770 1771 static void ensure_join(JavaThread* thread) { 1772 // We do not need to grab the Threads_lock, since we are operating on ourself. 1773 Handle threadObj(thread, thread->threadObj()); 1774 assert(threadObj.not_null(), "java thread object must exist"); 1775 ObjectLocker lock(threadObj, thread); 1776 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1777 thread->clear_pending_exception(); 1778 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1779 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1780 // Clear the native thread instance - this makes isAlive return false and allows the join() 1781 // to complete once we've done the notify_all below 1782 java_lang_Thread::set_thread(threadObj(), NULL); 1783 lock.notify_all(thread); 1784 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1785 thread->clear_pending_exception(); 1786 } 1787 1788 1789 // For any new cleanup additions, please check to see if they need to be applied to 1790 // cleanup_failed_attach_current_thread as well. 1791 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1792 assert(this == JavaThread::current(), "thread consistency check"); 1793 1794 elapsedTimer _timer_exit_phase1; 1795 elapsedTimer _timer_exit_phase2; 1796 elapsedTimer _timer_exit_phase3; 1797 elapsedTimer _timer_exit_phase4; 1798 1799 if (log_is_enabled(Debug, os, thread, timer)) { 1800 _timer_exit_phase1.start(); 1801 } 1802 1803 HandleMark hm(this); 1804 Handle uncaught_exception(this, this->pending_exception()); 1805 this->clear_pending_exception(); 1806 Handle threadObj(this, this->threadObj()); 1807 assert(threadObj.not_null(), "Java thread object should be created"); 1808 1809 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1810 { 1811 EXCEPTION_MARK; 1812 1813 CLEAR_PENDING_EXCEPTION; 1814 } 1815 if (!destroy_vm) { 1816 if (uncaught_exception.not_null()) { 1817 EXCEPTION_MARK; 1818 // Call method Thread.dispatchUncaughtException(). 1819 Klass* thread_klass = SystemDictionary::Thread_klass(); 1820 JavaValue result(T_VOID); 1821 JavaCalls::call_virtual(&result, 1822 threadObj, thread_klass, 1823 vmSymbols::dispatchUncaughtException_name(), 1824 vmSymbols::throwable_void_signature(), 1825 uncaught_exception, 1826 THREAD); 1827 if (HAS_PENDING_EXCEPTION) { 1828 ResourceMark rm(this); 1829 jio_fprintf(defaultStream::error_stream(), 1830 "\nException: %s thrown from the UncaughtExceptionHandler" 1831 " in thread \"%s\"\n", 1832 pending_exception()->klass()->external_name(), 1833 get_thread_name()); 1834 CLEAR_PENDING_EXCEPTION; 1835 } 1836 } 1837 1838 // Called before the java thread exit since we want to read info 1839 // from java_lang_Thread object 1840 EventThreadEnd event; 1841 if (event.should_commit()) { 1842 event.set_thread(JFR_THREAD_ID(this)); 1843 event.commit(); 1844 } 1845 1846 // Call after last event on thread 1847 JFR_ONLY(Jfr::on_thread_exit(this);) 1848 1849 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1850 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1851 // is deprecated anyhow. 1852 if (!is_Compiler_thread()) { 1853 int count = 3; 1854 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1855 EXCEPTION_MARK; 1856 JavaValue result(T_VOID); 1857 Klass* thread_klass = SystemDictionary::Thread_klass(); 1858 JavaCalls::call_virtual(&result, 1859 threadObj, thread_klass, 1860 vmSymbols::exit_method_name(), 1861 vmSymbols::void_method_signature(), 1862 THREAD); 1863 CLEAR_PENDING_EXCEPTION; 1864 } 1865 } 1866 // notify JVMTI 1867 if (JvmtiExport::should_post_thread_life()) { 1868 JvmtiExport::post_thread_end(this); 1869 } 1870 1871 // We have notified the agents that we are exiting, before we go on, 1872 // we must check for a pending external suspend request and honor it 1873 // in order to not surprise the thread that made the suspend request. 1874 while (true) { 1875 { 1876 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1877 if (!is_external_suspend()) { 1878 set_terminated(_thread_exiting); 1879 ThreadService::current_thread_exiting(this); 1880 break; 1881 } 1882 // Implied else: 1883 // Things get a little tricky here. We have a pending external 1884 // suspend request, but we are holding the SR_lock so we 1885 // can't just self-suspend. So we temporarily drop the lock 1886 // and then self-suspend. 1887 } 1888 1889 ThreadBlockInVM tbivm(this); 1890 java_suspend_self(); 1891 1892 // We're done with this suspend request, but we have to loop around 1893 // and check again. Eventually we will get SR_lock without a pending 1894 // external suspend request and will be able to mark ourselves as 1895 // exiting. 1896 } 1897 // no more external suspends are allowed at this point 1898 } else { 1899 // before_exit() has already posted JVMTI THREAD_END events 1900 } 1901 1902 if (log_is_enabled(Debug, os, thread, timer)) { 1903 _timer_exit_phase1.stop(); 1904 _timer_exit_phase2.start(); 1905 } 1906 // Notify waiters on thread object. This has to be done after exit() is called 1907 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1908 // group should have the destroyed bit set before waiters are notified). 1909 ensure_join(this); 1910 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1911 1912 if (log_is_enabled(Debug, os, thread, timer)) { 1913 _timer_exit_phase2.stop(); 1914 _timer_exit_phase3.start(); 1915 } 1916 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1917 // held by this thread must be released. The spec does not distinguish 1918 // between JNI-acquired and regular Java monitors. We can only see 1919 // regular Java monitors here if monitor enter-exit matching is broken. 1920 // 1921 // Optionally release any monitors for regular JavaThread exits. This 1922 // is provided as a work around for any bugs in monitor enter-exit 1923 // matching. This can be expensive so it is not enabled by default. 1924 // 1925 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1926 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1927 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1928 // Sanity check even though JNI DetachCurrentThread() would have 1929 // returned JNI_ERR if there was a Java frame. JavaThread exit 1930 // should be done executing Java code by the time we get here. 1931 assert(!this->has_last_Java_frame(), 1932 "should not have a Java frame when detaching or exiting"); 1933 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1934 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1935 } 1936 1937 // These things needs to be done while we are still a Java Thread. Make sure that thread 1938 // is in a consistent state, in case GC happens 1939 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1940 1941 if (active_handles() != NULL) { 1942 JNIHandleBlock* block = active_handles(); 1943 set_active_handles(NULL); 1944 JNIHandleBlock::release_block(block); 1945 } 1946 1947 if (free_handle_block() != NULL) { 1948 JNIHandleBlock* block = free_handle_block(); 1949 set_free_handle_block(NULL); 1950 JNIHandleBlock::release_block(block); 1951 } 1952 1953 // These have to be removed while this is still a valid thread. 1954 remove_stack_guard_pages(); 1955 1956 if (UseTLAB) { 1957 tlab().make_parsable(true); // retire TLAB 1958 } 1959 1960 if (JvmtiEnv::environments_might_exist()) { 1961 JvmtiExport::cleanup_thread(this); 1962 } 1963 1964 // We must flush any deferred card marks and other various GC barrier 1965 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 1966 // before removing a thread from the list of active threads. 1967 BarrierSet::barrier_set()->on_thread_detach(this); 1968 1969 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1970 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1971 os::current_thread_id()); 1972 1973 if (log_is_enabled(Debug, os, thread, timer)) { 1974 _timer_exit_phase3.stop(); 1975 _timer_exit_phase4.start(); 1976 } 1977 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1978 Threads::remove(this); 1979 1980 if (log_is_enabled(Debug, os, thread, timer)) { 1981 _timer_exit_phase4.stop(); 1982 ResourceMark rm(this); 1983 log_debug(os, thread, timer)("name='%s'" 1984 ", exit-phase1=" JLONG_FORMAT 1985 ", exit-phase2=" JLONG_FORMAT 1986 ", exit-phase3=" JLONG_FORMAT 1987 ", exit-phase4=" JLONG_FORMAT, 1988 get_thread_name(), 1989 _timer_exit_phase1.milliseconds(), 1990 _timer_exit_phase2.milliseconds(), 1991 _timer_exit_phase3.milliseconds(), 1992 _timer_exit_phase4.milliseconds()); 1993 } 1994 } 1995 1996 void JavaThread::cleanup_failed_attach_current_thread() { 1997 if (active_handles() != NULL) { 1998 JNIHandleBlock* block = active_handles(); 1999 set_active_handles(NULL); 2000 JNIHandleBlock::release_block(block); 2001 } 2002 2003 if (free_handle_block() != NULL) { 2004 JNIHandleBlock* block = free_handle_block(); 2005 set_free_handle_block(NULL); 2006 JNIHandleBlock::release_block(block); 2007 } 2008 2009 // These have to be removed while this is still a valid thread. 2010 remove_stack_guard_pages(); 2011 2012 if (UseTLAB) { 2013 tlab().make_parsable(true); // retire TLAB, if any 2014 } 2015 2016 BarrierSet::barrier_set()->on_thread_detach(this); 2017 2018 Threads::remove(this); 2019 this->smr_delete(); 2020 } 2021 2022 JavaThread* JavaThread::active() { 2023 Thread* thread = Thread::current(); 2024 if (thread->is_Java_thread()) { 2025 return (JavaThread*) thread; 2026 } else { 2027 assert(thread->is_VM_thread(), "this must be a vm thread"); 2028 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2029 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2030 assert(ret->is_Java_thread(), "must be a Java thread"); 2031 return ret; 2032 } 2033 } 2034 2035 bool JavaThread::is_lock_owned(address adr) const { 2036 if (Thread::is_lock_owned(adr)) return true; 2037 2038 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2039 if (chunk->contains(adr)) return true; 2040 } 2041 2042 return false; 2043 } 2044 2045 2046 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2047 chunk->set_next(monitor_chunks()); 2048 set_monitor_chunks(chunk); 2049 } 2050 2051 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2052 guarantee(monitor_chunks() != NULL, "must be non empty"); 2053 if (monitor_chunks() == chunk) { 2054 set_monitor_chunks(chunk->next()); 2055 } else { 2056 MonitorChunk* prev = monitor_chunks(); 2057 while (prev->next() != chunk) prev = prev->next(); 2058 prev->set_next(chunk->next()); 2059 } 2060 } 2061 2062 // JVM support. 2063 2064 // Note: this function shouldn't block if it's called in 2065 // _thread_in_native_trans state (such as from 2066 // check_special_condition_for_native_trans()). 2067 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2068 2069 if (has_last_Java_frame() && has_async_condition()) { 2070 // If we are at a polling page safepoint (not a poll return) 2071 // then we must defer async exception because live registers 2072 // will be clobbered by the exception path. Poll return is 2073 // ok because the call we a returning from already collides 2074 // with exception handling registers and so there is no issue. 2075 // (The exception handling path kills call result registers but 2076 // this is ok since the exception kills the result anyway). 2077 2078 if (is_at_poll_safepoint()) { 2079 // if the code we are returning to has deoptimized we must defer 2080 // the exception otherwise live registers get clobbered on the 2081 // exception path before deoptimization is able to retrieve them. 2082 // 2083 RegisterMap map(this, false); 2084 frame caller_fr = last_frame().sender(&map); 2085 assert(caller_fr.is_compiled_frame(), "what?"); 2086 if (caller_fr.is_deoptimized_frame()) { 2087 log_info(exceptions)("deferred async exception at compiled safepoint"); 2088 return; 2089 } 2090 } 2091 } 2092 2093 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2094 if (condition == _no_async_condition) { 2095 // Conditions have changed since has_special_runtime_exit_condition() 2096 // was called: 2097 // - if we were here only because of an external suspend request, 2098 // then that was taken care of above (or cancelled) so we are done 2099 // - if we were here because of another async request, then it has 2100 // been cleared between the has_special_runtime_exit_condition() 2101 // and now so again we are done 2102 return; 2103 } 2104 2105 // Check for pending async. exception 2106 if (_pending_async_exception != NULL) { 2107 // Only overwrite an already pending exception, if it is not a threadDeath. 2108 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2109 2110 // We cannot call Exceptions::_throw(...) here because we cannot block 2111 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2112 2113 LogTarget(Info, exceptions) lt; 2114 if (lt.is_enabled()) { 2115 ResourceMark rm; 2116 LogStream ls(lt); 2117 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2118 if (has_last_Java_frame()) { 2119 frame f = last_frame(); 2120 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2121 } 2122 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2123 } 2124 _pending_async_exception = NULL; 2125 clear_has_async_exception(); 2126 } 2127 } 2128 2129 if (check_unsafe_error && 2130 condition == _async_unsafe_access_error && !has_pending_exception()) { 2131 condition = _no_async_condition; // done 2132 switch (thread_state()) { 2133 case _thread_in_vm: { 2134 JavaThread* THREAD = this; 2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2136 } 2137 case _thread_in_native: { 2138 ThreadInVMfromNative tiv(this); 2139 JavaThread* THREAD = this; 2140 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2141 } 2142 case _thread_in_Java: { 2143 ThreadInVMfromJava tiv(this); 2144 JavaThread* THREAD = this; 2145 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2146 } 2147 default: 2148 ShouldNotReachHere(); 2149 } 2150 } 2151 2152 assert(condition == _no_async_condition || has_pending_exception() || 2153 (!check_unsafe_error && condition == _async_unsafe_access_error), 2154 "must have handled the async condition, if no exception"); 2155 } 2156 2157 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2158 // 2159 // Check for pending external suspend. Internal suspend requests do 2160 // not use handle_special_runtime_exit_condition(). 2161 // If JNIEnv proxies are allowed, don't self-suspend if the target 2162 // thread is not the current thread. In older versions of jdbx, jdbx 2163 // threads could call into the VM with another thread's JNIEnv so we 2164 // can be here operating on behalf of a suspended thread (4432884). 2165 bool do_self_suspend = is_external_suspend_with_lock(); 2166 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2167 // 2168 // Because thread is external suspended the safepoint code will count 2169 // thread as at a safepoint. This can be odd because we can be here 2170 // as _thread_in_Java which would normally transition to _thread_blocked 2171 // at a safepoint. We would like to mark the thread as _thread_blocked 2172 // before calling java_suspend_self like all other callers of it but 2173 // we must then observe proper safepoint protocol. (We can't leave 2174 // _thread_blocked with a safepoint in progress). However we can be 2175 // here as _thread_in_native_trans so we can't use a normal transition 2176 // constructor/destructor pair because they assert on that type of 2177 // transition. We could do something like: 2178 // 2179 // JavaThreadState state = thread_state(); 2180 // set_thread_state(_thread_in_vm); 2181 // { 2182 // ThreadBlockInVM tbivm(this); 2183 // java_suspend_self() 2184 // } 2185 // set_thread_state(_thread_in_vm_trans); 2186 // if (safepoint) block; 2187 // set_thread_state(state); 2188 // 2189 // but that is pretty messy. Instead we just go with the way the 2190 // code has worked before and note that this is the only path to 2191 // java_suspend_self that doesn't put the thread in _thread_blocked 2192 // mode. 2193 2194 frame_anchor()->make_walkable(this); 2195 java_suspend_self(); 2196 2197 // We might be here for reasons in addition to the self-suspend request 2198 // so check for other async requests. 2199 } 2200 2201 if (check_asyncs) { 2202 check_and_handle_async_exceptions(); 2203 } 2204 2205 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2206 } 2207 2208 void JavaThread::send_thread_stop(oop java_throwable) { 2209 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2210 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2211 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2212 2213 // Do not throw asynchronous exceptions against the compiler thread 2214 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2215 if (!can_call_java()) return; 2216 2217 { 2218 // Actually throw the Throwable against the target Thread - however 2219 // only if there is no thread death exception installed already. 2220 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2221 // If the topmost frame is a runtime stub, then we are calling into 2222 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2223 // must deoptimize the caller before continuing, as the compiled exception handler table 2224 // may not be valid 2225 if (has_last_Java_frame()) { 2226 frame f = last_frame(); 2227 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2228 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2229 RegisterMap reg_map(this, UseBiasedLocking); 2230 frame compiled_frame = f.sender(®_map); 2231 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2232 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2233 } 2234 } 2235 } 2236 2237 // Set async. pending exception in thread. 2238 set_pending_async_exception(java_throwable); 2239 2240 if (log_is_enabled(Info, exceptions)) { 2241 ResourceMark rm; 2242 log_info(exceptions)("Pending Async. exception installed of type: %s", 2243 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2244 } 2245 // for AbortVMOnException flag 2246 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2247 } 2248 } 2249 2250 2251 // Interrupt thread so it will wake up from a potential wait() 2252 Thread::interrupt(this); 2253 } 2254 2255 // External suspension mechanism. 2256 // 2257 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2258 // to any VM_locks and it is at a transition 2259 // Self-suspension will happen on the transition out of the vm. 2260 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2261 // 2262 // Guarantees on return: 2263 // + Target thread will not execute any new bytecode (that's why we need to 2264 // force a safepoint) 2265 // + Target thread will not enter any new monitors 2266 // 2267 void JavaThread::java_suspend() { 2268 ThreadsListHandle tlh; 2269 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2270 return; 2271 } 2272 2273 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2274 if (!is_external_suspend()) { 2275 // a racing resume has cancelled us; bail out now 2276 return; 2277 } 2278 2279 // suspend is done 2280 uint32_t debug_bits = 0; 2281 // Warning: is_ext_suspend_completed() may temporarily drop the 2282 // SR_lock to allow the thread to reach a stable thread state if 2283 // it is currently in a transient thread state. 2284 if (is_ext_suspend_completed(false /* !called_by_wait */, 2285 SuspendRetryDelay, &debug_bits)) { 2286 return; 2287 } 2288 } 2289 2290 VM_ThreadSuspend vm_suspend; 2291 VMThread::execute(&vm_suspend); 2292 } 2293 2294 // Part II of external suspension. 2295 // A JavaThread self suspends when it detects a pending external suspend 2296 // request. This is usually on transitions. It is also done in places 2297 // where continuing to the next transition would surprise the caller, 2298 // e.g., monitor entry. 2299 // 2300 // Returns the number of times that the thread self-suspended. 2301 // 2302 // Note: DO NOT call java_suspend_self() when you just want to block current 2303 // thread. java_suspend_self() is the second stage of cooperative 2304 // suspension for external suspend requests and should only be used 2305 // to complete an external suspend request. 2306 // 2307 int JavaThread::java_suspend_self() { 2308 int ret = 0; 2309 2310 // we are in the process of exiting so don't suspend 2311 if (is_exiting()) { 2312 clear_external_suspend(); 2313 return ret; 2314 } 2315 2316 assert(_anchor.walkable() || 2317 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2318 "must have walkable stack"); 2319 2320 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2321 2322 assert(!this->is_ext_suspended(), 2323 "a thread trying to self-suspend should not already be suspended"); 2324 2325 if (this->is_suspend_equivalent()) { 2326 // If we are self-suspending as a result of the lifting of a 2327 // suspend equivalent condition, then the suspend_equivalent 2328 // flag is not cleared until we set the ext_suspended flag so 2329 // that wait_for_ext_suspend_completion() returns consistent 2330 // results. 2331 this->clear_suspend_equivalent(); 2332 } 2333 2334 // A racing resume may have cancelled us before we grabbed SR_lock 2335 // above. Or another external suspend request could be waiting for us 2336 // by the time we return from SR_lock()->wait(). The thread 2337 // that requested the suspension may already be trying to walk our 2338 // stack and if we return now, we can change the stack out from under 2339 // it. This would be a "bad thing (TM)" and cause the stack walker 2340 // to crash. We stay self-suspended until there are no more pending 2341 // external suspend requests. 2342 while (is_external_suspend()) { 2343 ret++; 2344 this->set_ext_suspended(); 2345 2346 // _ext_suspended flag is cleared by java_resume() 2347 while (is_ext_suspended()) { 2348 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2349 } 2350 } 2351 2352 return ret; 2353 } 2354 2355 #ifdef ASSERT 2356 // Verify the JavaThread has not yet been published in the Threads::list, and 2357 // hence doesn't need protection from concurrent access at this stage. 2358 void JavaThread::verify_not_published() { 2359 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2360 // since an unpublished JavaThread doesn't participate in the 2361 // Thread-SMR protocol for keeping a ThreadsList alive. 2362 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2363 } 2364 #endif 2365 2366 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2367 // progress or when _suspend_flags is non-zero. 2368 // Current thread needs to self-suspend if there is a suspend request and/or 2369 // block if a safepoint is in progress. 2370 // Async exception ISN'T checked. 2371 // Note only the ThreadInVMfromNative transition can call this function 2372 // directly and when thread state is _thread_in_native_trans 2373 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2374 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2375 2376 JavaThread *curJT = JavaThread::current(); 2377 bool do_self_suspend = thread->is_external_suspend(); 2378 2379 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2380 2381 // If JNIEnv proxies are allowed, don't self-suspend if the target 2382 // thread is not the current thread. In older versions of jdbx, jdbx 2383 // threads could call into the VM with another thread's JNIEnv so we 2384 // can be here operating on behalf of a suspended thread (4432884). 2385 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2386 JavaThreadState state = thread->thread_state(); 2387 2388 // We mark this thread_blocked state as a suspend-equivalent so 2389 // that a caller to is_ext_suspend_completed() won't be confused. 2390 // The suspend-equivalent state is cleared by java_suspend_self(). 2391 thread->set_suspend_equivalent(); 2392 2393 // If the safepoint code sees the _thread_in_native_trans state, it will 2394 // wait until the thread changes to other thread state. There is no 2395 // guarantee on how soon we can obtain the SR_lock and complete the 2396 // self-suspend request. It would be a bad idea to let safepoint wait for 2397 // too long. Temporarily change the state to _thread_blocked to 2398 // let the VM thread know that this thread is ready for GC. The problem 2399 // of changing thread state is that safepoint could happen just after 2400 // java_suspend_self() returns after being resumed, and VM thread will 2401 // see the _thread_blocked state. We must check for safepoint 2402 // after restoring the state and make sure we won't leave while a safepoint 2403 // is in progress. 2404 thread->set_thread_state(_thread_blocked); 2405 thread->java_suspend_self(); 2406 thread->set_thread_state(state); 2407 2408 InterfaceSupport::serialize_thread_state_with_handler(thread); 2409 } 2410 2411 SafepointMechanism::block_if_requested(curJT); 2412 2413 if (thread->is_deopt_suspend()) { 2414 thread->clear_deopt_suspend(); 2415 RegisterMap map(thread, false); 2416 frame f = thread->last_frame(); 2417 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2418 f = f.sender(&map); 2419 } 2420 if (f.id() == thread->must_deopt_id()) { 2421 thread->clear_must_deopt_id(); 2422 f.deoptimize(thread); 2423 } else { 2424 fatal("missed deoptimization!"); 2425 } 2426 } 2427 2428 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2429 } 2430 2431 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2432 // progress or when _suspend_flags is non-zero. 2433 // Current thread needs to self-suspend if there is a suspend request and/or 2434 // block if a safepoint is in progress. 2435 // Also check for pending async exception (not including unsafe access error). 2436 // Note only the native==>VM/Java barriers can call this function and when 2437 // thread state is _thread_in_native_trans. 2438 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2439 check_safepoint_and_suspend_for_native_trans(thread); 2440 2441 if (thread->has_async_exception()) { 2442 // We are in _thread_in_native_trans state, don't handle unsafe 2443 // access error since that may block. 2444 thread->check_and_handle_async_exceptions(false); 2445 } 2446 } 2447 2448 // This is a variant of the normal 2449 // check_special_condition_for_native_trans with slightly different 2450 // semantics for use by critical native wrappers. It does all the 2451 // normal checks but also performs the transition back into 2452 // thread_in_Java state. This is required so that critical natives 2453 // can potentially block and perform a GC if they are the last thread 2454 // exiting the GCLocker. 2455 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2456 check_special_condition_for_native_trans(thread); 2457 2458 // Finish the transition 2459 thread->set_thread_state(_thread_in_Java); 2460 2461 if (thread->do_critical_native_unlock()) { 2462 ThreadInVMfromJavaNoAsyncException tiv(thread); 2463 GCLocker::unlock_critical(thread); 2464 thread->clear_critical_native_unlock(); 2465 } 2466 } 2467 2468 // We need to guarantee the Threads_lock here, since resumes are not 2469 // allowed during safepoint synchronization 2470 // Can only resume from an external suspension 2471 void JavaThread::java_resume() { 2472 assert_locked_or_safepoint(Threads_lock); 2473 2474 // Sanity check: thread is gone, has started exiting or the thread 2475 // was not externally suspended. 2476 ThreadsListHandle tlh; 2477 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2478 return; 2479 } 2480 2481 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2482 2483 clear_external_suspend(); 2484 2485 if (is_ext_suspended()) { 2486 clear_ext_suspended(); 2487 SR_lock()->notify_all(); 2488 } 2489 } 2490 2491 size_t JavaThread::_stack_red_zone_size = 0; 2492 size_t JavaThread::_stack_yellow_zone_size = 0; 2493 size_t JavaThread::_stack_reserved_zone_size = 0; 2494 size_t JavaThread::_stack_shadow_zone_size = 0; 2495 2496 void JavaThread::create_stack_guard_pages() { 2497 if (!os::uses_stack_guard_pages() || 2498 _stack_guard_state != stack_guard_unused || 2499 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2500 log_info(os, thread)("Stack guard page creation for thread " 2501 UINTX_FORMAT " disabled", os::current_thread_id()); 2502 return; 2503 } 2504 address low_addr = stack_end(); 2505 size_t len = stack_guard_zone_size(); 2506 2507 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2508 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2509 2510 int must_commit = os::must_commit_stack_guard_pages(); 2511 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2512 2513 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2514 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2515 return; 2516 } 2517 2518 if (os::guard_memory((char *) low_addr, len)) { 2519 _stack_guard_state = stack_guard_enabled; 2520 } else { 2521 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2522 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2523 if (os::uncommit_memory((char *) low_addr, len)) { 2524 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2525 } 2526 return; 2527 } 2528 2529 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2530 PTR_FORMAT "-" PTR_FORMAT ".", 2531 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2532 } 2533 2534 void JavaThread::remove_stack_guard_pages() { 2535 assert(Thread::current() == this, "from different thread"); 2536 if (_stack_guard_state == stack_guard_unused) return; 2537 address low_addr = stack_end(); 2538 size_t len = stack_guard_zone_size(); 2539 2540 if (os::must_commit_stack_guard_pages()) { 2541 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2542 _stack_guard_state = stack_guard_unused; 2543 } else { 2544 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2545 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2546 return; 2547 } 2548 } else { 2549 if (_stack_guard_state == stack_guard_unused) return; 2550 if (os::unguard_memory((char *) low_addr, len)) { 2551 _stack_guard_state = stack_guard_unused; 2552 } else { 2553 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2554 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2555 return; 2556 } 2557 } 2558 2559 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2560 PTR_FORMAT "-" PTR_FORMAT ".", 2561 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2562 } 2563 2564 void JavaThread::enable_stack_reserved_zone() { 2565 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2566 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2567 2568 // The base notation is from the stack's point of view, growing downward. 2569 // We need to adjust it to work correctly with guard_memory() 2570 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2571 2572 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2573 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2574 2575 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2576 _stack_guard_state = stack_guard_enabled; 2577 } else { 2578 warning("Attempt to guard stack reserved zone failed."); 2579 } 2580 enable_register_stack_guard(); 2581 } 2582 2583 void JavaThread::disable_stack_reserved_zone() { 2584 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2585 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2586 2587 // Simply return if called for a thread that does not use guard pages. 2588 if (_stack_guard_state == stack_guard_unused) return; 2589 2590 // The base notation is from the stack's point of view, growing downward. 2591 // We need to adjust it to work correctly with guard_memory() 2592 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2593 2594 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2595 _stack_guard_state = stack_guard_reserved_disabled; 2596 } else { 2597 warning("Attempt to unguard stack reserved zone failed."); 2598 } 2599 disable_register_stack_guard(); 2600 } 2601 2602 void JavaThread::enable_stack_yellow_reserved_zone() { 2603 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2604 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2605 2606 // The base notation is from the stacks point of view, growing downward. 2607 // We need to adjust it to work correctly with guard_memory() 2608 address base = stack_red_zone_base(); 2609 2610 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2611 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2612 2613 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2614 _stack_guard_state = stack_guard_enabled; 2615 } else { 2616 warning("Attempt to guard stack yellow zone failed."); 2617 } 2618 enable_register_stack_guard(); 2619 } 2620 2621 void JavaThread::disable_stack_yellow_reserved_zone() { 2622 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2623 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2624 2625 // Simply return if called for a thread that does not use guard pages. 2626 if (_stack_guard_state == stack_guard_unused) return; 2627 2628 // The base notation is from the stacks point of view, growing downward. 2629 // We need to adjust it to work correctly with guard_memory() 2630 address base = stack_red_zone_base(); 2631 2632 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2633 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2634 } else { 2635 warning("Attempt to unguard stack yellow zone failed."); 2636 } 2637 disable_register_stack_guard(); 2638 } 2639 2640 void JavaThread::enable_stack_red_zone() { 2641 // The base notation is from the stacks point of view, growing downward. 2642 // We need to adjust it to work correctly with guard_memory() 2643 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2644 address base = stack_red_zone_base() - stack_red_zone_size(); 2645 2646 guarantee(base < stack_base(), "Error calculating stack red zone"); 2647 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2648 2649 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2650 warning("Attempt to guard stack red zone failed."); 2651 } 2652 } 2653 2654 void JavaThread::disable_stack_red_zone() { 2655 // The base notation is from the stacks point of view, growing downward. 2656 // We need to adjust it to work correctly with guard_memory() 2657 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2658 address base = stack_red_zone_base() - stack_red_zone_size(); 2659 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2660 warning("Attempt to unguard stack red zone failed."); 2661 } 2662 } 2663 2664 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2665 // ignore is there is no stack 2666 if (!has_last_Java_frame()) return; 2667 // traverse the stack frames. Starts from top frame. 2668 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2669 frame* fr = fst.current(); 2670 f(fr, fst.register_map()); 2671 } 2672 } 2673 2674 2675 #ifndef PRODUCT 2676 // Deoptimization 2677 // Function for testing deoptimization 2678 void JavaThread::deoptimize() { 2679 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2680 StackFrameStream fst(this, UseBiasedLocking); 2681 bool deopt = false; // Dump stack only if a deopt actually happens. 2682 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2683 // Iterate over all frames in the thread and deoptimize 2684 for (; !fst.is_done(); fst.next()) { 2685 if (fst.current()->can_be_deoptimized()) { 2686 2687 if (only_at) { 2688 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2689 // consists of comma or carriage return separated numbers so 2690 // search for the current bci in that string. 2691 address pc = fst.current()->pc(); 2692 nmethod* nm = (nmethod*) fst.current()->cb(); 2693 ScopeDesc* sd = nm->scope_desc_at(pc); 2694 char buffer[8]; 2695 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2696 size_t len = strlen(buffer); 2697 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2698 while (found != NULL) { 2699 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2700 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2701 // Check that the bci found is bracketed by terminators. 2702 break; 2703 } 2704 found = strstr(found + 1, buffer); 2705 } 2706 if (!found) { 2707 continue; 2708 } 2709 } 2710 2711 if (DebugDeoptimization && !deopt) { 2712 deopt = true; // One-time only print before deopt 2713 tty->print_cr("[BEFORE Deoptimization]"); 2714 trace_frames(); 2715 trace_stack(); 2716 } 2717 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2718 } 2719 } 2720 2721 if (DebugDeoptimization && deopt) { 2722 tty->print_cr("[AFTER Deoptimization]"); 2723 trace_frames(); 2724 } 2725 } 2726 2727 2728 // Make zombies 2729 void JavaThread::make_zombies() { 2730 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2731 if (fst.current()->can_be_deoptimized()) { 2732 // it is a Java nmethod 2733 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2734 nm->make_not_entrant(); 2735 } 2736 } 2737 } 2738 #endif // PRODUCT 2739 2740 2741 void JavaThread::deoptimized_wrt_marked_nmethods() { 2742 if (!has_last_Java_frame()) return; 2743 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2744 StackFrameStream fst(this, UseBiasedLocking); 2745 for (; !fst.is_done(); fst.next()) { 2746 if (fst.current()->should_be_deoptimized()) { 2747 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2748 } 2749 } 2750 } 2751 2752 2753 // If the caller is a NamedThread, then remember, in the current scope, 2754 // the given JavaThread in its _processed_thread field. 2755 class RememberProcessedThread: public StackObj { 2756 NamedThread* _cur_thr; 2757 public: 2758 RememberProcessedThread(JavaThread* jthr) { 2759 Thread* thread = Thread::current(); 2760 if (thread->is_Named_thread()) { 2761 _cur_thr = (NamedThread *)thread; 2762 _cur_thr->set_processed_thread(jthr); 2763 } else { 2764 _cur_thr = NULL; 2765 } 2766 } 2767 2768 ~RememberProcessedThread() { 2769 if (_cur_thr) { 2770 _cur_thr->set_processed_thread(NULL); 2771 } 2772 } 2773 }; 2774 2775 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2776 // Verify that the deferred card marks have been flushed. 2777 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2778 2779 // Traverse the GCHandles 2780 Thread::oops_do(f, cf); 2781 2782 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2783 2784 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2785 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2786 2787 if (has_last_Java_frame()) { 2788 // Record JavaThread to GC thread 2789 RememberProcessedThread rpt(this); 2790 2791 // Traverse the privileged stack 2792 if (_privileged_stack_top != NULL) { 2793 _privileged_stack_top->oops_do(f); 2794 } 2795 2796 // traverse the registered growable array 2797 if (_array_for_gc != NULL) { 2798 for (int index = 0; index < _array_for_gc->length(); index++) { 2799 f->do_oop(_array_for_gc->adr_at(index)); 2800 } 2801 } 2802 2803 // Traverse the monitor chunks 2804 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2805 chunk->oops_do(f); 2806 } 2807 2808 // Traverse the execution stack 2809 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2810 fst.current()->oops_do(f, cf, fst.register_map()); 2811 } 2812 } 2813 2814 // callee_target is never live across a gc point so NULL it here should 2815 // it still contain a methdOop. 2816 2817 set_callee_target(NULL); 2818 2819 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2820 // If we have deferred set_locals there might be oops waiting to be 2821 // written 2822 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2823 if (list != NULL) { 2824 for (int i = 0; i < list->length(); i++) { 2825 list->at(i)->oops_do(f); 2826 } 2827 } 2828 2829 // Traverse instance variables at the end since the GC may be moving things 2830 // around using this function 2831 f->do_oop((oop*) &_threadObj); 2832 f->do_oop((oop*) &_vm_result); 2833 f->do_oop((oop*) &_exception_oop); 2834 f->do_oop((oop*) &_pending_async_exception); 2835 2836 if (jvmti_thread_state() != NULL) { 2837 jvmti_thread_state()->oops_do(f); 2838 } 2839 } 2840 2841 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2842 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2843 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2844 2845 if (has_last_Java_frame()) { 2846 // Traverse the execution stack 2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2848 fst.current()->nmethods_do(cf); 2849 } 2850 } 2851 } 2852 2853 void JavaThread::metadata_do(void f(Metadata*)) { 2854 if (has_last_Java_frame()) { 2855 // Traverse the execution stack to call f() on the methods in the stack 2856 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2857 fst.current()->metadata_do(f); 2858 } 2859 } else if (is_Compiler_thread()) { 2860 // need to walk ciMetadata in current compile tasks to keep alive. 2861 CompilerThread* ct = (CompilerThread*)this; 2862 if (ct->env() != NULL) { 2863 ct->env()->metadata_do(f); 2864 } 2865 CompileTask* task = ct->task(); 2866 if (task != NULL) { 2867 task->metadata_do(f); 2868 } 2869 } 2870 } 2871 2872 // Printing 2873 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2874 switch (_thread_state) { 2875 case _thread_uninitialized: return "_thread_uninitialized"; 2876 case _thread_new: return "_thread_new"; 2877 case _thread_new_trans: return "_thread_new_trans"; 2878 case _thread_in_native: return "_thread_in_native"; 2879 case _thread_in_native_trans: return "_thread_in_native_trans"; 2880 case _thread_in_vm: return "_thread_in_vm"; 2881 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2882 case _thread_in_Java: return "_thread_in_Java"; 2883 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2884 case _thread_blocked: return "_thread_blocked"; 2885 case _thread_blocked_trans: return "_thread_blocked_trans"; 2886 default: return "unknown thread state"; 2887 } 2888 } 2889 2890 #ifndef PRODUCT 2891 void JavaThread::print_thread_state_on(outputStream *st) const { 2892 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2893 }; 2894 void JavaThread::print_thread_state() const { 2895 print_thread_state_on(tty); 2896 } 2897 #endif // PRODUCT 2898 2899 // Called by Threads::print() for VM_PrintThreads operation 2900 void JavaThread::print_on(outputStream *st) const { 2901 st->print_raw("\""); 2902 st->print_raw(get_thread_name()); 2903 st->print_raw("\" "); 2904 oop thread_oop = threadObj(); 2905 if (thread_oop != NULL) { 2906 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2907 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2908 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2909 } 2910 Thread::print_on(st); 2911 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2912 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2913 if (thread_oop != NULL) { 2914 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2915 } 2916 #ifndef PRODUCT 2917 print_thread_state_on(st); 2918 _safepoint_state->print_on(st); 2919 #endif // PRODUCT 2920 if (is_Compiler_thread()) { 2921 CompileTask *task = ((CompilerThread*)this)->task(); 2922 if (task != NULL) { 2923 st->print(" Compiling: "); 2924 task->print(st, NULL, true, false); 2925 } else { 2926 st->print(" No compile task"); 2927 } 2928 st->cr(); 2929 } 2930 } 2931 2932 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2933 st->print("%s", get_thread_name_string(buf, buflen)); 2934 } 2935 2936 // Called by fatal error handler. The difference between this and 2937 // JavaThread::print() is that we can't grab lock or allocate memory. 2938 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2939 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2940 oop thread_obj = threadObj(); 2941 if (thread_obj != NULL) { 2942 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2943 } 2944 st->print(" ["); 2945 st->print("%s", _get_thread_state_name(_thread_state)); 2946 if (osthread()) { 2947 st->print(", id=%d", osthread()->thread_id()); 2948 } 2949 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2950 p2i(stack_end()), p2i(stack_base())); 2951 st->print("]"); 2952 2953 ThreadsSMRSupport::print_info_on(this, st); 2954 return; 2955 } 2956 2957 // Verification 2958 2959 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2960 2961 void JavaThread::verify() { 2962 // Verify oops in the thread. 2963 oops_do(&VerifyOopClosure::verify_oop, NULL); 2964 2965 // Verify the stack frames. 2966 frames_do(frame_verify); 2967 } 2968 2969 // CR 6300358 (sub-CR 2137150) 2970 // Most callers of this method assume that it can't return NULL but a 2971 // thread may not have a name whilst it is in the process of attaching to 2972 // the VM - see CR 6412693, and there are places where a JavaThread can be 2973 // seen prior to having it's threadObj set (eg JNI attaching threads and 2974 // if vm exit occurs during initialization). These cases can all be accounted 2975 // for such that this method never returns NULL. 2976 const char* JavaThread::get_thread_name() const { 2977 #ifdef ASSERT 2978 // early safepoints can hit while current thread does not yet have TLS 2979 if (!SafepointSynchronize::is_at_safepoint()) { 2980 Thread *cur = Thread::current(); 2981 if (!(cur->is_Java_thread() && cur == this)) { 2982 // Current JavaThreads are allowed to get their own name without 2983 // the Threads_lock. 2984 assert_locked_or_safepoint(Threads_lock); 2985 } 2986 } 2987 #endif // ASSERT 2988 return get_thread_name_string(); 2989 } 2990 2991 // Returns a non-NULL representation of this thread's name, or a suitable 2992 // descriptive string if there is no set name 2993 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2994 const char* name_str; 2995 oop thread_obj = threadObj(); 2996 if (thread_obj != NULL) { 2997 oop name = java_lang_Thread::name(thread_obj); 2998 if (name != NULL) { 2999 if (buf == NULL) { 3000 name_str = java_lang_String::as_utf8_string(name); 3001 } else { 3002 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3003 } 3004 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3005 name_str = "<no-name - thread is attaching>"; 3006 } else { 3007 name_str = Thread::name(); 3008 } 3009 } else { 3010 name_str = Thread::name(); 3011 } 3012 assert(name_str != NULL, "unexpected NULL thread name"); 3013 return name_str; 3014 } 3015 3016 3017 const char* JavaThread::get_threadgroup_name() const { 3018 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3019 oop thread_obj = threadObj(); 3020 if (thread_obj != NULL) { 3021 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3022 if (thread_group != NULL) { 3023 // ThreadGroup.name can be null 3024 return java_lang_ThreadGroup::name(thread_group); 3025 } 3026 } 3027 return NULL; 3028 } 3029 3030 const char* JavaThread::get_parent_name() const { 3031 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3032 oop thread_obj = threadObj(); 3033 if (thread_obj != NULL) { 3034 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3035 if (thread_group != NULL) { 3036 oop parent = java_lang_ThreadGroup::parent(thread_group); 3037 if (parent != NULL) { 3038 // ThreadGroup.name can be null 3039 return java_lang_ThreadGroup::name(parent); 3040 } 3041 } 3042 } 3043 return NULL; 3044 } 3045 3046 ThreadPriority JavaThread::java_priority() const { 3047 oop thr_oop = threadObj(); 3048 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3049 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3050 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3051 return priority; 3052 } 3053 3054 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3055 3056 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3057 // Link Java Thread object <-> C++ Thread 3058 3059 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3060 // and put it into a new Handle. The Handle "thread_oop" can then 3061 // be used to pass the C++ thread object to other methods. 3062 3063 // Set the Java level thread object (jthread) field of the 3064 // new thread (a JavaThread *) to C++ thread object using the 3065 // "thread_oop" handle. 3066 3067 // Set the thread field (a JavaThread *) of the 3068 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3069 3070 Handle thread_oop(Thread::current(), 3071 JNIHandles::resolve_non_null(jni_thread)); 3072 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3073 "must be initialized"); 3074 set_threadObj(thread_oop()); 3075 java_lang_Thread::set_thread(thread_oop(), this); 3076 3077 if (prio == NoPriority) { 3078 prio = java_lang_Thread::priority(thread_oop()); 3079 assert(prio != NoPriority, "A valid priority should be present"); 3080 } 3081 3082 // Push the Java priority down to the native thread; needs Threads_lock 3083 Thread::set_priority(this, prio); 3084 3085 // Add the new thread to the Threads list and set it in motion. 3086 // We must have threads lock in order to call Threads::add. 3087 // It is crucial that we do not block before the thread is 3088 // added to the Threads list for if a GC happens, then the java_thread oop 3089 // will not be visited by GC. 3090 Threads::add(this); 3091 } 3092 3093 oop JavaThread::current_park_blocker() { 3094 // Support for JSR-166 locks 3095 oop thread_oop = threadObj(); 3096 if (thread_oop != NULL && 3097 JDK_Version::current().supports_thread_park_blocker()) { 3098 return java_lang_Thread::park_blocker(thread_oop); 3099 } 3100 return NULL; 3101 } 3102 3103 3104 void JavaThread::print_stack_on(outputStream* st) { 3105 if (!has_last_Java_frame()) return; 3106 ResourceMark rm; 3107 HandleMark hm; 3108 3109 RegisterMap reg_map(this); 3110 vframe* start_vf = last_java_vframe(®_map); 3111 int count = 0; 3112 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3113 if (f->is_java_frame()) { 3114 javaVFrame* jvf = javaVFrame::cast(f); 3115 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3116 3117 // Print out lock information 3118 if (JavaMonitorsInStackTrace) { 3119 jvf->print_lock_info_on(st, count); 3120 } 3121 } else { 3122 // Ignore non-Java frames 3123 } 3124 3125 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3126 count++; 3127 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3128 } 3129 } 3130 3131 3132 // JVMTI PopFrame support 3133 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3134 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3135 if (in_bytes(size_in_bytes) != 0) { 3136 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3137 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3138 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3139 } 3140 } 3141 3142 void* JavaThread::popframe_preserved_args() { 3143 return _popframe_preserved_args; 3144 } 3145 3146 ByteSize JavaThread::popframe_preserved_args_size() { 3147 return in_ByteSize(_popframe_preserved_args_size); 3148 } 3149 3150 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3151 int sz = in_bytes(popframe_preserved_args_size()); 3152 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3153 return in_WordSize(sz / wordSize); 3154 } 3155 3156 void JavaThread::popframe_free_preserved_args() { 3157 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3158 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3159 _popframe_preserved_args = NULL; 3160 _popframe_preserved_args_size = 0; 3161 } 3162 3163 #ifndef PRODUCT 3164 3165 void JavaThread::trace_frames() { 3166 tty->print_cr("[Describe stack]"); 3167 int frame_no = 1; 3168 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3169 tty->print(" %d. ", frame_no++); 3170 fst.current()->print_value_on(tty, this); 3171 tty->cr(); 3172 } 3173 } 3174 3175 class PrintAndVerifyOopClosure: public OopClosure { 3176 protected: 3177 template <class T> inline void do_oop_work(T* p) { 3178 oop obj = RawAccess<>::oop_load(p); 3179 if (obj == NULL) return; 3180 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3181 if (oopDesc::is_oop_or_null(obj)) { 3182 if (obj->is_objArray()) { 3183 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3184 } else { 3185 obj->print(); 3186 } 3187 } else { 3188 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3189 } 3190 tty->cr(); 3191 } 3192 public: 3193 virtual void do_oop(oop* p) { do_oop_work(p); } 3194 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3195 }; 3196 3197 3198 static void oops_print(frame* f, const RegisterMap *map) { 3199 PrintAndVerifyOopClosure print; 3200 f->print_value(); 3201 f->oops_do(&print, NULL, (RegisterMap*)map); 3202 } 3203 3204 // Print our all the locations that contain oops and whether they are 3205 // valid or not. This useful when trying to find the oldest frame 3206 // where an oop has gone bad since the frame walk is from youngest to 3207 // oldest. 3208 void JavaThread::trace_oops() { 3209 tty->print_cr("[Trace oops]"); 3210 frames_do(oops_print); 3211 } 3212 3213 3214 #ifdef ASSERT 3215 // Print or validate the layout of stack frames 3216 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3217 ResourceMark rm; 3218 PRESERVE_EXCEPTION_MARK; 3219 FrameValues values; 3220 int frame_no = 0; 3221 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3222 fst.current()->describe(values, ++frame_no); 3223 if (depth == frame_no) break; 3224 } 3225 if (validate_only) { 3226 values.validate(); 3227 } else { 3228 tty->print_cr("[Describe stack layout]"); 3229 values.print(this); 3230 } 3231 } 3232 #endif 3233 3234 void JavaThread::trace_stack_from(vframe* start_vf) { 3235 ResourceMark rm; 3236 int vframe_no = 1; 3237 for (vframe* f = start_vf; f; f = f->sender()) { 3238 if (f->is_java_frame()) { 3239 javaVFrame::cast(f)->print_activation(vframe_no++); 3240 } else { 3241 f->print(); 3242 } 3243 if (vframe_no > StackPrintLimit) { 3244 tty->print_cr("...<more frames>..."); 3245 return; 3246 } 3247 } 3248 } 3249 3250 3251 void JavaThread::trace_stack() { 3252 if (!has_last_Java_frame()) return; 3253 ResourceMark rm; 3254 HandleMark hm; 3255 RegisterMap reg_map(this); 3256 trace_stack_from(last_java_vframe(®_map)); 3257 } 3258 3259 3260 #endif // PRODUCT 3261 3262 3263 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3264 assert(reg_map != NULL, "a map must be given"); 3265 frame f = last_frame(); 3266 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3267 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3268 } 3269 return NULL; 3270 } 3271 3272 3273 Klass* JavaThread::security_get_caller_class(int depth) { 3274 vframeStream vfst(this); 3275 vfst.security_get_caller_frame(depth); 3276 if (!vfst.at_end()) { 3277 return vfst.method()->method_holder(); 3278 } 3279 return NULL; 3280 } 3281 3282 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3283 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3284 CompileBroker::compiler_thread_loop(); 3285 } 3286 3287 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3288 NMethodSweeper::sweeper_loop(); 3289 } 3290 3291 // Create a CompilerThread 3292 CompilerThread::CompilerThread(CompileQueue* queue, 3293 CompilerCounters* counters) 3294 : JavaThread(&compiler_thread_entry) { 3295 _env = NULL; 3296 _log = NULL; 3297 _task = NULL; 3298 _queue = queue; 3299 _counters = counters; 3300 _buffer_blob = NULL; 3301 _compiler = NULL; 3302 3303 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3304 resource_area()->bias_to(mtCompiler); 3305 3306 #ifndef PRODUCT 3307 _ideal_graph_printer = NULL; 3308 #endif 3309 } 3310 3311 CompilerThread::~CompilerThread() { 3312 // Delete objects which were allocated on heap. 3313 delete _counters; 3314 } 3315 3316 bool CompilerThread::can_call_java() const { 3317 return _compiler != NULL && _compiler->is_jvmci(); 3318 } 3319 3320 // Create sweeper thread 3321 CodeCacheSweeperThread::CodeCacheSweeperThread() 3322 : JavaThread(&sweeper_thread_entry) { 3323 _scanned_compiled_method = NULL; 3324 } 3325 3326 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3327 JavaThread::oops_do(f, cf); 3328 if (_scanned_compiled_method != NULL && cf != NULL) { 3329 // Safepoints can occur when the sweeper is scanning an nmethod so 3330 // process it here to make sure it isn't unloaded in the middle of 3331 // a scan. 3332 cf->do_code_blob(_scanned_compiled_method); 3333 } 3334 } 3335 3336 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3337 JavaThread::nmethods_do(cf); 3338 if (_scanned_compiled_method != NULL && cf != NULL) { 3339 // Safepoints can occur when the sweeper is scanning an nmethod so 3340 // process it here to make sure it isn't unloaded in the middle of 3341 // a scan. 3342 cf->do_code_blob(_scanned_compiled_method); 3343 } 3344 } 3345 3346 3347 // ======= Threads ======== 3348 3349 // The Threads class links together all active threads, and provides 3350 // operations over all threads. It is protected by the Threads_lock, 3351 // which is also used in other global contexts like safepointing. 3352 // ThreadsListHandles are used to safely perform operations on one 3353 // or more threads without the risk of the thread exiting during the 3354 // operation. 3355 // 3356 // Note: The Threads_lock is currently more widely used than we 3357 // would like. We are actively migrating Threads_lock uses to other 3358 // mechanisms in order to reduce Threads_lock contention. 3359 3360 JavaThread* Threads::_thread_list = NULL; 3361 int Threads::_number_of_threads = 0; 3362 int Threads::_number_of_non_daemon_threads = 0; 3363 int Threads::_return_code = 0; 3364 int Threads::_thread_claim_parity = 0; 3365 size_t JavaThread::_stack_size_at_create = 0; 3366 3367 #ifdef ASSERT 3368 bool Threads::_vm_complete = false; 3369 #endif 3370 3371 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3372 Prefetch::read((void*)addr, prefetch_interval); 3373 return *addr; 3374 } 3375 3376 // Possibly the ugliest for loop the world has seen. C++ does not allow 3377 // multiple types in the declaration section of the for loop. In this case 3378 // we are only dealing with pointers and hence can cast them. It looks ugly 3379 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3380 #define DO_JAVA_THREADS(LIST, X) \ 3381 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3382 *MACRO_list = (JavaThread*)(LIST), \ 3383 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3384 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3385 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3386 MACRO_current_p != MACRO_end; \ 3387 MACRO_current_p++, \ 3388 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3389 3390 // All JavaThreads 3391 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3392 3393 // All non-JavaThreads (i.e., every non-JavaThread in the system). 3394 void Threads::non_java_threads_do(ThreadClosure* tc) { 3395 // Someday we could have a table or list of all non-JavaThreads. 3396 // For now, just manually iterate through them. 3397 tc->do_thread(VMThread::vm_thread()); 3398 if (Universe::heap() != NULL) { 3399 Universe::heap()->gc_threads_do(tc); 3400 } 3401 WatcherThread *wt = WatcherThread::watcher_thread(); 3402 // Strictly speaking, the following NULL check isn't sufficient to make sure 3403 // the data for WatcherThread is still valid upon being examined. However, 3404 // considering that WatchThread terminates when the VM is on the way to 3405 // exit at safepoint, the chance of the above is extremely small. The right 3406 // way to prevent termination of WatcherThread would be to acquire 3407 // Terminator_lock, but we can't do that without violating the lock rank 3408 // checking in some cases. 3409 if (wt != NULL) { 3410 tc->do_thread(wt); 3411 } 3412 3413 #if INCLUDE_JFR 3414 Thread* sampler_thread = Jfr::sampler_thread(); 3415 if (sampler_thread != NULL) { 3416 tc->do_thread(sampler_thread); 3417 } 3418 3419 #endif 3420 3421 // If CompilerThreads ever become non-JavaThreads, add them here 3422 } 3423 3424 // All JavaThreads 3425 void Threads::java_threads_do(ThreadClosure* tc) { 3426 assert_locked_or_safepoint(Threads_lock); 3427 // ALL_JAVA_THREADS iterates through all JavaThreads. 3428 ALL_JAVA_THREADS(p) { 3429 tc->do_thread(p); 3430 } 3431 } 3432 3433 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3434 assert_locked_or_safepoint(Threads_lock); 3435 java_threads_do(tc); 3436 tc->do_thread(VMThread::vm_thread()); 3437 } 3438 3439 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3440 void Threads::threads_do(ThreadClosure* tc) { 3441 assert_locked_or_safepoint(Threads_lock); 3442 java_threads_do(tc); 3443 non_java_threads_do(tc); 3444 } 3445 3446 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3447 int cp = Threads::thread_claim_parity(); 3448 ALL_JAVA_THREADS(p) { 3449 if (p->claim_oops_do(is_par, cp)) { 3450 tc->do_thread(p); 3451 } 3452 } 3453 VMThread* vmt = VMThread::vm_thread(); 3454 if (vmt->claim_oops_do(is_par, cp)) { 3455 tc->do_thread(vmt); 3456 } 3457 } 3458 3459 // The system initialization in the library has three phases. 3460 // 3461 // Phase 1: java.lang.System class initialization 3462 // java.lang.System is a primordial class loaded and initialized 3463 // by the VM early during startup. java.lang.System.<clinit> 3464 // only does registerNatives and keeps the rest of the class 3465 // initialization work later until thread initialization completes. 3466 // 3467 // System.initPhase1 initializes the system properties, the static 3468 // fields in, out, and err. Set up java signal handlers, OS-specific 3469 // system settings, and thread group of the main thread. 3470 static void call_initPhase1(TRAPS) { 3471 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3472 JavaValue result(T_VOID); 3473 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3474 vmSymbols::void_method_signature(), CHECK); 3475 } 3476 3477 // Phase 2. Module system initialization 3478 // This will initialize the module system. Only java.base classes 3479 // can be loaded until phase 2 completes. 3480 // 3481 // Call System.initPhase2 after the compiler initialization and jsr292 3482 // classes get initialized because module initialization runs a lot of java 3483 // code, that for performance reasons, should be compiled. Also, this will 3484 // enable the startup code to use lambda and other language features in this 3485 // phase and onward. 3486 // 3487 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3488 static void call_initPhase2(TRAPS) { 3489 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3490 3491 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3492 3493 JavaValue result(T_INT); 3494 JavaCallArguments args; 3495 args.push_int(DisplayVMOutputToStderr); 3496 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3497 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3498 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3499 if (result.get_jint() != JNI_OK) { 3500 vm_exit_during_initialization(); // no message or exception 3501 } 3502 3503 universe_post_module_init(); 3504 } 3505 3506 // Phase 3. final setup - set security manager, system class loader and TCCL 3507 // 3508 // This will instantiate and set the security manager, set the system class 3509 // loader as well as the thread context class loader. The security manager 3510 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3511 // other modules or the application's classpath. 3512 static void call_initPhase3(TRAPS) { 3513 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3514 JavaValue result(T_VOID); 3515 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3516 vmSymbols::void_method_signature(), CHECK); 3517 } 3518 3519 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3520 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3521 3522 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3523 create_vm_init_libraries(); 3524 } 3525 3526 initialize_class(vmSymbols::java_lang_String(), CHECK); 3527 3528 // Inject CompactStrings value after the static initializers for String ran. 3529 java_lang_String::set_compact_strings(CompactStrings); 3530 3531 // Initialize java_lang.System (needed before creating the thread) 3532 initialize_class(vmSymbols::java_lang_System(), CHECK); 3533 // The VM creates & returns objects of this class. Make sure it's initialized. 3534 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3535 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3536 Handle thread_group = create_initial_thread_group(CHECK); 3537 Universe::set_main_thread_group(thread_group()); 3538 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3539 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3540 main_thread->set_threadObj(thread_object); 3541 // Set thread status to running since main thread has 3542 // been started and running. 3543 java_lang_Thread::set_thread_status(thread_object, 3544 java_lang_Thread::RUNNABLE); 3545 3546 // The VM creates objects of this class. 3547 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3548 3549 // The VM preresolves methods to these classes. Make sure that they get initialized 3550 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3551 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3552 3553 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3554 call_initPhase1(CHECK); 3555 3556 // get the Java runtime name after java.lang.System is initialized 3557 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3558 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3559 3560 // an instance of OutOfMemory exception has been allocated earlier 3561 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3562 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3563 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3564 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3565 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3566 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3567 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3568 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3569 } 3570 3571 void Threads::initialize_jsr292_core_classes(TRAPS) { 3572 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3573 3574 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3575 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3576 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3577 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3578 } 3579 3580 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3581 extern void JDK_Version_init(); 3582 3583 // Preinitialize version info. 3584 VM_Version::early_initialize(); 3585 3586 // Check version 3587 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3588 3589 // Initialize library-based TLS 3590 ThreadLocalStorage::init(); 3591 3592 // Initialize the output stream module 3593 ostream_init(); 3594 3595 // Process java launcher properties. 3596 Arguments::process_sun_java_launcher_properties(args); 3597 3598 // Initialize the os module 3599 os::init(); 3600 3601 // Record VM creation timing statistics 3602 TraceVmCreationTime create_vm_timer; 3603 create_vm_timer.start(); 3604 3605 // Initialize system properties. 3606 Arguments::init_system_properties(); 3607 3608 // So that JDK version can be used as a discriminator when parsing arguments 3609 JDK_Version_init(); 3610 3611 // Update/Initialize System properties after JDK version number is known 3612 Arguments::init_version_specific_system_properties(); 3613 3614 // Make sure to initialize log configuration *before* parsing arguments 3615 LogConfiguration::initialize(create_vm_timer.begin_time()); 3616 3617 // Parse arguments 3618 // Note: this internally calls os::init_container_support() 3619 jint parse_result = Arguments::parse(args); 3620 if (parse_result != JNI_OK) return parse_result; 3621 3622 os::init_before_ergo(); 3623 3624 jint ergo_result = Arguments::apply_ergo(); 3625 if (ergo_result != JNI_OK) return ergo_result; 3626 3627 // Final check of all ranges after ergonomics which may change values. 3628 if (!JVMFlagRangeList::check_ranges()) { 3629 return JNI_EINVAL; 3630 } 3631 3632 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3633 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3634 if (!constraint_result) { 3635 return JNI_EINVAL; 3636 } 3637 3638 JVMFlagWriteableList::mark_startup(); 3639 3640 if (PauseAtStartup) { 3641 os::pause(); 3642 } 3643 3644 HOTSPOT_VM_INIT_BEGIN(); 3645 3646 // Timing (must come after argument parsing) 3647 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3648 3649 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3650 // Initialize assert poison page mechanism. 3651 if (ShowRegistersOnAssert) { 3652 initialize_assert_poison(); 3653 } 3654 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3655 3656 // Initialize the os module after parsing the args 3657 jint os_init_2_result = os::init_2(); 3658 if (os_init_2_result != JNI_OK) return os_init_2_result; 3659 3660 SafepointMechanism::initialize(); 3661 3662 jint adjust_after_os_result = Arguments::adjust_after_os(); 3663 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3664 3665 // Initialize output stream logging 3666 ostream_init_log(); 3667 3668 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3669 // Must be before create_vm_init_agents() 3670 if (Arguments::init_libraries_at_startup()) { 3671 convert_vm_init_libraries_to_agents(); 3672 } 3673 3674 // Launch -agentlib/-agentpath and converted -Xrun agents 3675 if (Arguments::init_agents_at_startup()) { 3676 create_vm_init_agents(); 3677 } 3678 3679 // Initialize Threads state 3680 _thread_list = NULL; 3681 _number_of_threads = 0; 3682 _number_of_non_daemon_threads = 0; 3683 3684 // Initialize global data structures and create system classes in heap 3685 vm_init_globals(); 3686 3687 #if INCLUDE_JVMCI 3688 if (JVMCICounterSize > 0) { 3689 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3690 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3691 } else { 3692 JavaThread::_jvmci_old_thread_counters = NULL; 3693 } 3694 #endif // INCLUDE_JVMCI 3695 3696 // Attach the main thread to this os thread 3697 JavaThread* main_thread = new JavaThread(); 3698 main_thread->set_thread_state(_thread_in_vm); 3699 main_thread->initialize_thread_current(); 3700 // must do this before set_active_handles 3701 main_thread->record_stack_base_and_size(); 3702 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3703 3704 if (!main_thread->set_as_starting_thread()) { 3705 vm_shutdown_during_initialization( 3706 "Failed necessary internal allocation. Out of swap space"); 3707 main_thread->smr_delete(); 3708 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3709 return JNI_ENOMEM; 3710 } 3711 3712 // Enable guard page *after* os::create_main_thread(), otherwise it would 3713 // crash Linux VM, see notes in os_linux.cpp. 3714 main_thread->create_stack_guard_pages(); 3715 3716 // Initialize Java-Level synchronization subsystem 3717 ObjectMonitor::Initialize(); 3718 3719 // Initialize global modules 3720 jint status = init_globals(); 3721 if (status != JNI_OK) { 3722 main_thread->smr_delete(); 3723 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3724 return status; 3725 } 3726 3727 JFR_ONLY(Jfr::on_vm_init();) 3728 3729 // Should be done after the heap is fully created 3730 main_thread->cache_global_variables(); 3731 3732 HandleMark hm; 3733 3734 { MutexLocker mu(Threads_lock); 3735 Threads::add(main_thread); 3736 } 3737 3738 // Any JVMTI raw monitors entered in onload will transition into 3739 // real raw monitor. VM is setup enough here for raw monitor enter. 3740 JvmtiExport::transition_pending_onload_raw_monitors(); 3741 3742 // Create the VMThread 3743 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3744 3745 VMThread::create(); 3746 Thread* vmthread = VMThread::vm_thread(); 3747 3748 if (!os::create_thread(vmthread, os::vm_thread)) { 3749 vm_exit_during_initialization("Cannot create VM thread. " 3750 "Out of system resources."); 3751 } 3752 3753 // Wait for the VM thread to become ready, and VMThread::run to initialize 3754 // Monitors can have spurious returns, must always check another state flag 3755 { 3756 MutexLocker ml(Notify_lock); 3757 os::start_thread(vmthread); 3758 while (vmthread->active_handles() == NULL) { 3759 Notify_lock->wait(); 3760 } 3761 } 3762 } 3763 3764 assert(Universe::is_fully_initialized(), "not initialized"); 3765 if (VerifyDuringStartup) { 3766 // Make sure we're starting with a clean slate. 3767 VM_Verify verify_op; 3768 VMThread::execute(&verify_op); 3769 } 3770 3771 Thread* THREAD = Thread::current(); 3772 3773 // Always call even when there are not JVMTI environments yet, since environments 3774 // may be attached late and JVMTI must track phases of VM execution 3775 JvmtiExport::enter_early_start_phase(); 3776 3777 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3778 JvmtiExport::post_early_vm_start(); 3779 3780 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3781 3782 // We need this for ClassDataSharing - the initial vm.info property is set 3783 // with the default value of CDS "sharing" which may be reset through 3784 // command line options. 3785 reset_vm_info_property(CHECK_JNI_ERR); 3786 3787 quicken_jni_functions(); 3788 3789 // No more stub generation allowed after that point. 3790 StubCodeDesc::freeze(); 3791 3792 // Set flag that basic initialization has completed. Used by exceptions and various 3793 // debug stuff, that does not work until all basic classes have been initialized. 3794 set_init_completed(); 3795 3796 LogConfiguration::post_initialize(); 3797 Metaspace::post_initialize(); 3798 3799 HOTSPOT_VM_INIT_END(); 3800 3801 // record VM initialization completion time 3802 #if INCLUDE_MANAGEMENT 3803 Management::record_vm_init_completed(); 3804 #endif // INCLUDE_MANAGEMENT 3805 3806 // Signal Dispatcher needs to be started before VMInit event is posted 3807 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3808 3809 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3810 if (!DisableAttachMechanism) { 3811 AttachListener::vm_start(); 3812 if (StartAttachListener || AttachListener::init_at_startup()) { 3813 AttachListener::init(); 3814 } 3815 } 3816 3817 // Launch -Xrun agents 3818 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3819 // back-end can launch with -Xdebug -Xrunjdwp. 3820 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3821 create_vm_init_libraries(); 3822 } 3823 3824 if (CleanChunkPoolAsync) { 3825 Chunk::start_chunk_pool_cleaner_task(); 3826 } 3827 3828 // initialize compiler(s) 3829 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3830 #if INCLUDE_JVMCI 3831 bool force_JVMCI_intialization = false; 3832 if (EnableJVMCI) { 3833 // Initialize JVMCI eagerly when it is explicitly requested. 3834 // Or when JVMCIPrintProperties is enabled. 3835 // The JVMCI Java initialization code will read this flag and 3836 // do the printing if it's set. 3837 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3838 3839 if (!force_JVMCI_intialization) { 3840 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3841 // compilations via JVMCI will not actually block until JVMCI is initialized. 3842 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3843 } 3844 } 3845 #endif 3846 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3847 // Postpone completion of compiler initialization to after JVMCI 3848 // is initialized to avoid timeouts of blocking compilations. 3849 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3850 CompileBroker::compilation_init_phase2(); 3851 } 3852 #endif 3853 3854 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3855 // It is done after compilers are initialized, because otherwise compilations of 3856 // signature polymorphic MH intrinsics can be missed 3857 // (see SystemDictionary::find_method_handle_intrinsic). 3858 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3859 3860 // This will initialize the module system. Only java.base classes can be 3861 // loaded until phase 2 completes 3862 call_initPhase2(CHECK_JNI_ERR); 3863 3864 // Always call even when there are not JVMTI environments yet, since environments 3865 // may be attached late and JVMTI must track phases of VM execution 3866 JvmtiExport::enter_start_phase(); 3867 3868 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3869 JvmtiExport::post_vm_start(); 3870 3871 // Final system initialization including security manager and system class loader 3872 call_initPhase3(CHECK_JNI_ERR); 3873 3874 // cache the system and platform class loaders 3875 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3876 3877 #if INCLUDE_CDS 3878 if (DumpSharedSpaces) { 3879 // capture the module path info from the ModuleEntryTable 3880 ClassLoader::initialize_module_path(THREAD); 3881 } 3882 #endif 3883 3884 #if INCLUDE_JVMCI 3885 if (force_JVMCI_intialization) { 3886 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3887 CompileBroker::compilation_init_phase2(); 3888 } 3889 #endif 3890 3891 // Always call even when there are not JVMTI environments yet, since environments 3892 // may be attached late and JVMTI must track phases of VM execution 3893 JvmtiExport::enter_live_phase(); 3894 3895 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3896 JvmtiExport::post_vm_initialized(); 3897 3898 JFR_ONLY(Jfr::on_vm_start();) 3899 3900 #if INCLUDE_MANAGEMENT 3901 Management::initialize(THREAD); 3902 3903 if (HAS_PENDING_EXCEPTION) { 3904 // management agent fails to start possibly due to 3905 // configuration problem and is responsible for printing 3906 // stack trace if appropriate. Simply exit VM. 3907 vm_exit(1); 3908 } 3909 #endif // INCLUDE_MANAGEMENT 3910 3911 if (MemProfiling) MemProfiler::engage(); 3912 StatSampler::engage(); 3913 if (CheckJNICalls) JniPeriodicChecker::engage(); 3914 3915 BiasedLocking::init(); 3916 3917 #if INCLUDE_RTM_OPT 3918 RTMLockingCounters::init(); 3919 #endif 3920 3921 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3922 call_postVMInitHook(THREAD); 3923 // The Java side of PostVMInitHook.run must deal with all 3924 // exceptions and provide means of diagnosis. 3925 if (HAS_PENDING_EXCEPTION) { 3926 CLEAR_PENDING_EXCEPTION; 3927 } 3928 } 3929 3930 { 3931 MutexLocker ml(PeriodicTask_lock); 3932 // Make sure the WatcherThread can be started by WatcherThread::start() 3933 // or by dynamic enrollment. 3934 WatcherThread::make_startable(); 3935 // Start up the WatcherThread if there are any periodic tasks 3936 // NOTE: All PeriodicTasks should be registered by now. If they 3937 // aren't, late joiners might appear to start slowly (we might 3938 // take a while to process their first tick). 3939 if (PeriodicTask::num_tasks() > 0) { 3940 WatcherThread::start(); 3941 } 3942 } 3943 3944 create_vm_timer.end(); 3945 #ifdef ASSERT 3946 _vm_complete = true; 3947 #endif 3948 3949 if (DumpSharedSpaces) { 3950 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3951 ShouldNotReachHere(); 3952 } 3953 3954 return JNI_OK; 3955 } 3956 3957 // type for the Agent_OnLoad and JVM_OnLoad entry points 3958 extern "C" { 3959 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3960 } 3961 // Find a command line agent library and return its entry point for 3962 // -agentlib: -agentpath: -Xrun 3963 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3964 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3965 const char *on_load_symbols[], 3966 size_t num_symbol_entries) { 3967 OnLoadEntry_t on_load_entry = NULL; 3968 void *library = NULL; 3969 3970 if (!agent->valid()) { 3971 char buffer[JVM_MAXPATHLEN]; 3972 char ebuf[1024] = ""; 3973 const char *name = agent->name(); 3974 const char *msg = "Could not find agent library "; 3975 3976 // First check to see if agent is statically linked into executable 3977 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3978 library = agent->os_lib(); 3979 } else if (agent->is_absolute_path()) { 3980 library = os::dll_load(name, ebuf, sizeof ebuf); 3981 if (library == NULL) { 3982 const char *sub_msg = " in absolute path, with error: "; 3983 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3984 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3985 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3986 // If we can't find the agent, exit. 3987 vm_exit_during_initialization(buf, NULL); 3988 FREE_C_HEAP_ARRAY(char, buf); 3989 } 3990 } else { 3991 // Try to load the agent from the standard dll directory 3992 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3993 name)) { 3994 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3995 } 3996 if (library == NULL) { // Try the library path directory. 3997 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 3998 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3999 } 4000 if (library == NULL) { 4001 const char *sub_msg = " on the library path, with error: "; 4002 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4003 4004 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4005 strlen(ebuf) + strlen(sub_msg2) + 1; 4006 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4007 if (!agent->is_instrument_lib()) { 4008 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4009 } else { 4010 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4011 } 4012 // If we can't find the agent, exit. 4013 vm_exit_during_initialization(buf, NULL); 4014 FREE_C_HEAP_ARRAY(char, buf); 4015 } 4016 } 4017 } 4018 agent->set_os_lib(library); 4019 agent->set_valid(); 4020 } 4021 4022 // Find the OnLoad function. 4023 on_load_entry = 4024 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4025 false, 4026 on_load_symbols, 4027 num_symbol_entries)); 4028 return on_load_entry; 4029 } 4030 4031 // Find the JVM_OnLoad entry point 4032 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4033 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4034 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4035 } 4036 4037 // Find the Agent_OnLoad entry point 4038 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4039 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4040 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4041 } 4042 4043 // For backwards compatibility with -Xrun 4044 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4045 // treated like -agentpath: 4046 // Must be called before agent libraries are created 4047 void Threads::convert_vm_init_libraries_to_agents() { 4048 AgentLibrary* agent; 4049 AgentLibrary* next; 4050 4051 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4052 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4053 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4054 4055 // If there is an JVM_OnLoad function it will get called later, 4056 // otherwise see if there is an Agent_OnLoad 4057 if (on_load_entry == NULL) { 4058 on_load_entry = lookup_agent_on_load(agent); 4059 if (on_load_entry != NULL) { 4060 // switch it to the agent list -- so that Agent_OnLoad will be called, 4061 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4062 Arguments::convert_library_to_agent(agent); 4063 } else { 4064 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4065 } 4066 } 4067 } 4068 } 4069 4070 // Create agents for -agentlib: -agentpath: and converted -Xrun 4071 // Invokes Agent_OnLoad 4072 // Called very early -- before JavaThreads exist 4073 void Threads::create_vm_init_agents() { 4074 extern struct JavaVM_ main_vm; 4075 AgentLibrary* agent; 4076 4077 JvmtiExport::enter_onload_phase(); 4078 4079 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4080 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4081 4082 if (on_load_entry != NULL) { 4083 // Invoke the Agent_OnLoad function 4084 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4085 if (err != JNI_OK) { 4086 vm_exit_during_initialization("agent library failed to init", agent->name()); 4087 } 4088 } else { 4089 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4090 } 4091 } 4092 JvmtiExport::enter_primordial_phase(); 4093 } 4094 4095 extern "C" { 4096 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4097 } 4098 4099 void Threads::shutdown_vm_agents() { 4100 // Send any Agent_OnUnload notifications 4101 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4102 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4103 extern struct JavaVM_ main_vm; 4104 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4105 4106 // Find the Agent_OnUnload function. 4107 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4108 os::find_agent_function(agent, 4109 false, 4110 on_unload_symbols, 4111 num_symbol_entries)); 4112 4113 // Invoke the Agent_OnUnload function 4114 if (unload_entry != NULL) { 4115 JavaThread* thread = JavaThread::current(); 4116 ThreadToNativeFromVM ttn(thread); 4117 HandleMark hm(thread); 4118 (*unload_entry)(&main_vm); 4119 } 4120 } 4121 } 4122 4123 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4124 // Invokes JVM_OnLoad 4125 void Threads::create_vm_init_libraries() { 4126 extern struct JavaVM_ main_vm; 4127 AgentLibrary* agent; 4128 4129 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4130 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4131 4132 if (on_load_entry != NULL) { 4133 // Invoke the JVM_OnLoad function 4134 JavaThread* thread = JavaThread::current(); 4135 ThreadToNativeFromVM ttn(thread); 4136 HandleMark hm(thread); 4137 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4138 if (err != JNI_OK) { 4139 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4140 } 4141 } else { 4142 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4143 } 4144 } 4145 } 4146 4147 4148 // Last thread running calls java.lang.Shutdown.shutdown() 4149 void JavaThread::invoke_shutdown_hooks() { 4150 HandleMark hm(this); 4151 4152 // We could get here with a pending exception, if so clear it now. 4153 if (this->has_pending_exception()) { 4154 this->clear_pending_exception(); 4155 } 4156 4157 EXCEPTION_MARK; 4158 Klass* shutdown_klass = 4159 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4160 THREAD); 4161 if (shutdown_klass != NULL) { 4162 // SystemDictionary::resolve_or_null will return null if there was 4163 // an exception. If we cannot load the Shutdown class, just don't 4164 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4165 // won't be run. Note that if a shutdown hook was registered, 4166 // the Shutdown class would have already been loaded 4167 // (Runtime.addShutdownHook will load it). 4168 JavaValue result(T_VOID); 4169 JavaCalls::call_static(&result, 4170 shutdown_klass, 4171 vmSymbols::shutdown_method_name(), 4172 vmSymbols::void_method_signature(), 4173 THREAD); 4174 } 4175 CLEAR_PENDING_EXCEPTION; 4176 } 4177 4178 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4179 // the program falls off the end of main(). Another VM exit path is through 4180 // vm_exit() when the program calls System.exit() to return a value or when 4181 // there is a serious error in VM. The two shutdown paths are not exactly 4182 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4183 // and VM_Exit op at VM level. 4184 // 4185 // Shutdown sequence: 4186 // + Shutdown native memory tracking if it is on 4187 // + Wait until we are the last non-daemon thread to execute 4188 // <-- every thing is still working at this moment --> 4189 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4190 // shutdown hooks 4191 // + Call before_exit(), prepare for VM exit 4192 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4193 // currently the only user of this mechanism is File.deleteOnExit()) 4194 // > stop StatSampler, watcher thread, CMS threads, 4195 // post thread end and vm death events to JVMTI, 4196 // stop signal thread 4197 // + Call JavaThread::exit(), it will: 4198 // > release JNI handle blocks, remove stack guard pages 4199 // > remove this thread from Threads list 4200 // <-- no more Java code from this thread after this point --> 4201 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4202 // the compiler threads at safepoint 4203 // <-- do not use anything that could get blocked by Safepoint --> 4204 // + Disable tracing at JNI/JVM barriers 4205 // + Set _vm_exited flag for threads that are still running native code 4206 // + Delete this thread 4207 // + Call exit_globals() 4208 // > deletes tty 4209 // > deletes PerfMemory resources 4210 // + Return to caller 4211 4212 bool Threads::destroy_vm() { 4213 JavaThread* thread = JavaThread::current(); 4214 4215 #ifdef ASSERT 4216 _vm_complete = false; 4217 #endif 4218 // Wait until we are the last non-daemon thread to execute 4219 { MutexLocker nu(Threads_lock); 4220 while (Threads::number_of_non_daemon_threads() > 1) 4221 // This wait should make safepoint checks, wait without a timeout, 4222 // and wait as a suspend-equivalent condition. 4223 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4224 Mutex::_as_suspend_equivalent_flag); 4225 } 4226 4227 EventShutdown e; 4228 if (e.should_commit()) { 4229 e.set_reason("No remaining non-daemon Java threads"); 4230 e.commit(); 4231 } 4232 4233 // Hang forever on exit if we are reporting an error. 4234 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4235 os::infinite_sleep(); 4236 } 4237 os::wait_for_keypress_at_exit(); 4238 4239 // run Java level shutdown hooks 4240 thread->invoke_shutdown_hooks(); 4241 4242 before_exit(thread); 4243 4244 thread->exit(true); 4245 4246 // Stop VM thread. 4247 { 4248 // 4945125 The vm thread comes to a safepoint during exit. 4249 // GC vm_operations can get caught at the safepoint, and the 4250 // heap is unparseable if they are caught. Grab the Heap_lock 4251 // to prevent this. The GC vm_operations will not be able to 4252 // queue until after the vm thread is dead. After this point, 4253 // we'll never emerge out of the safepoint before the VM exits. 4254 4255 MutexLocker ml(Heap_lock); 4256 4257 VMThread::wait_for_vm_thread_exit(); 4258 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4259 VMThread::destroy(); 4260 } 4261 4262 // Now, all Java threads are gone except daemon threads. Daemon threads 4263 // running Java code or in VM are stopped by the Safepoint. However, 4264 // daemon threads executing native code are still running. But they 4265 // will be stopped at native=>Java/VM barriers. Note that we can't 4266 // simply kill or suspend them, as it is inherently deadlock-prone. 4267 4268 VM_Exit::set_vm_exited(); 4269 4270 // Clean up ideal graph printers after the VMThread has started 4271 // the final safepoint which will block all the Compiler threads. 4272 // Note that this Thread has already logically exited so the 4273 // clean_up() function's use of a JavaThreadIteratorWithHandle 4274 // would be a problem except set_vm_exited() has remembered the 4275 // shutdown thread which is granted a policy exception. 4276 #if defined(COMPILER2) && !defined(PRODUCT) 4277 IdealGraphPrinter::clean_up(); 4278 #endif 4279 4280 notify_vm_shutdown(); 4281 4282 // We are after VM_Exit::set_vm_exited() so we can't call 4283 // thread->smr_delete() or we will block on the Threads_lock. 4284 // Deleting the shutdown thread here is safe because another 4285 // JavaThread cannot have an active ThreadsListHandle for 4286 // this JavaThread. 4287 delete thread; 4288 4289 #if INCLUDE_JVMCI 4290 if (JVMCICounterSize > 0) { 4291 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4292 } 4293 #endif 4294 4295 // exit_globals() will delete tty 4296 exit_globals(); 4297 4298 LogConfiguration::finalize(); 4299 4300 return true; 4301 } 4302 4303 4304 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4305 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4306 return is_supported_jni_version(version); 4307 } 4308 4309 4310 jboolean Threads::is_supported_jni_version(jint version) { 4311 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4312 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4313 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4314 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4315 if (version == JNI_VERSION_9) return JNI_TRUE; 4316 if (version == JNI_VERSION_10) return JNI_TRUE; 4317 return JNI_FALSE; 4318 } 4319 4320 4321 void Threads::add(JavaThread* p, bool force_daemon) { 4322 // The threads lock must be owned at this point 4323 assert_locked_or_safepoint(Threads_lock); 4324 4325 BarrierSet::barrier_set()->on_thread_attach(p); 4326 4327 p->set_next(_thread_list); 4328 _thread_list = p; 4329 4330 // Once a JavaThread is added to the Threads list, smr_delete() has 4331 // to be used to delete it. Otherwise we can just delete it directly. 4332 p->set_on_thread_list(); 4333 4334 _number_of_threads++; 4335 oop threadObj = p->threadObj(); 4336 bool daemon = true; 4337 // Bootstrapping problem: threadObj can be null for initial 4338 // JavaThread (or for threads attached via JNI) 4339 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4340 _number_of_non_daemon_threads++; 4341 daemon = false; 4342 } 4343 4344 ThreadService::add_thread(p, daemon); 4345 4346 // Maintain fast thread list 4347 ThreadsSMRSupport::add_thread(p); 4348 4349 // Possible GC point. 4350 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4351 } 4352 4353 void Threads::remove(JavaThread* p) { 4354 4355 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4356 ObjectSynchronizer::omFlush(p); 4357 4358 // Extra scope needed for Thread_lock, so we can check 4359 // that we do not remove thread without safepoint code notice 4360 { MutexLocker ml(Threads_lock); 4361 4362 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4363 4364 // Maintain fast thread list 4365 ThreadsSMRSupport::remove_thread(p); 4366 4367 JavaThread* current = _thread_list; 4368 JavaThread* prev = NULL; 4369 4370 while (current != p) { 4371 prev = current; 4372 current = current->next(); 4373 } 4374 4375 if (prev) { 4376 prev->set_next(current->next()); 4377 } else { 4378 _thread_list = p->next(); 4379 } 4380 4381 _number_of_threads--; 4382 oop threadObj = p->threadObj(); 4383 bool daemon = true; 4384 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4385 _number_of_non_daemon_threads--; 4386 daemon = false; 4387 4388 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4389 // on destroy_vm will wake up. 4390 if (number_of_non_daemon_threads() == 1) { 4391 Threads_lock->notify_all(); 4392 } 4393 } 4394 ThreadService::remove_thread(p, daemon); 4395 4396 // Make sure that safepoint code disregard this thread. This is needed since 4397 // the thread might mess around with locks after this point. This can cause it 4398 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4399 // of this thread since it is removed from the queue. 4400 p->set_terminated_value(); 4401 } // unlock Threads_lock 4402 4403 // Since Events::log uses a lock, we grab it outside the Threads_lock 4404 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4405 } 4406 4407 // Operations on the Threads list for GC. These are not explicitly locked, 4408 // but the garbage collector must provide a safe context for them to run. 4409 // In particular, these things should never be called when the Threads_lock 4410 // is held by some other thread. (Note: the Safepoint abstraction also 4411 // uses the Threads_lock to guarantee this property. It also makes sure that 4412 // all threads gets blocked when exiting or starting). 4413 4414 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4415 ALL_JAVA_THREADS(p) { 4416 p->oops_do(f, cf); 4417 } 4418 VMThread::vm_thread()->oops_do(f, cf); 4419 } 4420 4421 void Threads::change_thread_claim_parity() { 4422 // Set the new claim parity. 4423 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4424 "Not in range."); 4425 _thread_claim_parity++; 4426 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4427 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4428 "Not in range."); 4429 } 4430 4431 #ifdef ASSERT 4432 void Threads::assert_all_threads_claimed() { 4433 ALL_JAVA_THREADS(p) { 4434 const int thread_parity = p->oops_do_parity(); 4435 assert((thread_parity == _thread_claim_parity), 4436 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4437 } 4438 VMThread* vmt = VMThread::vm_thread(); 4439 const int thread_parity = vmt->oops_do_parity(); 4440 assert((thread_parity == _thread_claim_parity), 4441 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4442 } 4443 #endif // ASSERT 4444 4445 class ParallelOopsDoThreadClosure : public ThreadClosure { 4446 private: 4447 OopClosure* _f; 4448 CodeBlobClosure* _cf; 4449 public: 4450 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4451 void do_thread(Thread* t) { 4452 t->oops_do(_f, _cf); 4453 } 4454 }; 4455 4456 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4457 ParallelOopsDoThreadClosure tc(f, cf); 4458 possibly_parallel_threads_do(is_par, &tc); 4459 } 4460 4461 void Threads::nmethods_do(CodeBlobClosure* cf) { 4462 ALL_JAVA_THREADS(p) { 4463 // This is used by the code cache sweeper to mark nmethods that are active 4464 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4465 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4466 if(!p->is_Code_cache_sweeper_thread()) { 4467 p->nmethods_do(cf); 4468 } 4469 } 4470 } 4471 4472 void Threads::metadata_do(void f(Metadata*)) { 4473 ALL_JAVA_THREADS(p) { 4474 p->metadata_do(f); 4475 } 4476 } 4477 4478 class ThreadHandlesClosure : public ThreadClosure { 4479 void (*_f)(Metadata*); 4480 public: 4481 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4482 virtual void do_thread(Thread* thread) { 4483 thread->metadata_handles_do(_f); 4484 } 4485 }; 4486 4487 void Threads::metadata_handles_do(void f(Metadata*)) { 4488 // Only walk the Handles in Thread. 4489 ThreadHandlesClosure handles_closure(f); 4490 threads_do(&handles_closure); 4491 } 4492 4493 void Threads::deoptimized_wrt_marked_nmethods() { 4494 ALL_JAVA_THREADS(p) { 4495 p->deoptimized_wrt_marked_nmethods(); 4496 } 4497 } 4498 4499 4500 // Get count Java threads that are waiting to enter the specified monitor. 4501 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4502 int count, 4503 address monitor) { 4504 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4505 4506 int i = 0; 4507 DO_JAVA_THREADS(t_list, p) { 4508 if (!p->can_call_java()) continue; 4509 4510 address pending = (address)p->current_pending_monitor(); 4511 if (pending == monitor) { // found a match 4512 if (i < count) result->append(p); // save the first count matches 4513 i++; 4514 } 4515 } 4516 4517 return result; 4518 } 4519 4520 4521 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4522 address owner) { 4523 // NULL owner means not locked so we can skip the search 4524 if (owner == NULL) return NULL; 4525 4526 DO_JAVA_THREADS(t_list, p) { 4527 // first, see if owner is the address of a Java thread 4528 if (owner == (address)p) return p; 4529 } 4530 4531 // Cannot assert on lack of success here since this function may be 4532 // used by code that is trying to report useful problem information 4533 // like deadlock detection. 4534 if (UseHeavyMonitors) return NULL; 4535 4536 // If we didn't find a matching Java thread and we didn't force use of 4537 // heavyweight monitors, then the owner is the stack address of the 4538 // Lock Word in the owning Java thread's stack. 4539 // 4540 JavaThread* the_owner = NULL; 4541 DO_JAVA_THREADS(t_list, q) { 4542 if (q->is_lock_owned(owner)) { 4543 the_owner = q; 4544 break; 4545 } 4546 } 4547 4548 // cannot assert on lack of success here; see above comment 4549 return the_owner; 4550 } 4551 4552 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4553 void Threads::print_on(outputStream* st, bool print_stacks, 4554 bool internal_format, bool print_concurrent_locks) { 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); 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 // * Consider schedctl.sc_nopreempt to cover the critical section. 4805 // 4806 4807 4808 const intptr_t LOCKBIT = 1; 4809 4810 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4811 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4812 if (w == 0) return; 4813 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4814 return; 4815 } 4816 4817 TEVENT(muxAcquire - Contention); 4818 ParkEvent * const Self = Thread::current()->_MuxEvent; 4819 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4820 for (;;) { 4821 int its = (os::is_MP() ? 100 : 0) + 1; 4822 4823 // Optional spin phase: spin-then-park strategy 4824 while (--its >= 0) { 4825 w = *Lock; 4826 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4827 return; 4828 } 4829 } 4830 4831 Self->reset(); 4832 Self->OnList = intptr_t(Lock); 4833 // The following fence() isn't _strictly necessary as the subsequent 4834 // CAS() both serializes execution and ratifies the fetched *Lock value. 4835 OrderAccess::fence(); 4836 for (;;) { 4837 w = *Lock; 4838 if ((w & LOCKBIT) == 0) { 4839 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4840 Self->OnList = 0; // hygiene - allows stronger asserts 4841 return; 4842 } 4843 continue; // Interference -- *Lock changed -- Just retry 4844 } 4845 assert(w & LOCKBIT, "invariant"); 4846 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4847 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4848 } 4849 4850 while (Self->OnList != 0) { 4851 Self->park(); 4852 } 4853 } 4854 } 4855 4856 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4857 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4858 if (w == 0) return; 4859 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4860 return; 4861 } 4862 4863 TEVENT(muxAcquire - Contention); 4864 ParkEvent * ReleaseAfter = NULL; 4865 if (ev == NULL) { 4866 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4867 } 4868 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4869 for (;;) { 4870 guarantee(ev->OnList == 0, "invariant"); 4871 int its = (os::is_MP() ? 100 : 0) + 1; 4872 4873 // Optional spin phase: spin-then-park strategy 4874 while (--its >= 0) { 4875 w = *Lock; 4876 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4877 if (ReleaseAfter != NULL) { 4878 ParkEvent::Release(ReleaseAfter); 4879 } 4880 return; 4881 } 4882 } 4883 4884 ev->reset(); 4885 ev->OnList = intptr_t(Lock); 4886 // The following fence() isn't _strictly necessary as the subsequent 4887 // CAS() both serializes execution and ratifies the fetched *Lock value. 4888 OrderAccess::fence(); 4889 for (;;) { 4890 w = *Lock; 4891 if ((w & LOCKBIT) == 0) { 4892 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4893 ev->OnList = 0; 4894 // We call ::Release while holding the outer lock, thus 4895 // artificially lengthening the critical section. 4896 // Consider deferring the ::Release() until the subsequent unlock(), 4897 // after we've dropped the outer lock. 4898 if (ReleaseAfter != NULL) { 4899 ParkEvent::Release(ReleaseAfter); 4900 } 4901 return; 4902 } 4903 continue; // Interference -- *Lock changed -- Just retry 4904 } 4905 assert(w & LOCKBIT, "invariant"); 4906 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4907 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4908 } 4909 4910 while (ev->OnList != 0) { 4911 ev->park(); 4912 } 4913 } 4914 } 4915 4916 // Release() must extract a successor from the list and then wake that thread. 4917 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4918 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4919 // Release() would : 4920 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4921 // (B) Extract a successor from the private list "in-hand" 4922 // (C) attempt to CAS() the residual back into *Lock over null. 4923 // If there were any newly arrived threads and the CAS() would fail. 4924 // In that case Release() would detach the RATs, re-merge the list in-hand 4925 // with the RATs and repeat as needed. Alternately, Release() might 4926 // detach and extract a successor, but then pass the residual list to the wakee. 4927 // The wakee would be responsible for reattaching and remerging before it 4928 // competed for the lock. 4929 // 4930 // Both "pop" and DMR are immune from ABA corruption -- there can be 4931 // multiple concurrent pushers, but only one popper or detacher. 4932 // This implementation pops from the head of the list. This is unfair, 4933 // but tends to provide excellent throughput as hot threads remain hot. 4934 // (We wake recently run threads first). 4935 // 4936 // All paths through muxRelease() will execute a CAS. 4937 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4938 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4939 // executed within the critical section are complete and globally visible before the 4940 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4941 void Thread::muxRelease(volatile intptr_t * Lock) { 4942 for (;;) { 4943 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4944 assert(w & LOCKBIT, "invariant"); 4945 if (w == LOCKBIT) return; 4946 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4947 assert(List != NULL, "invariant"); 4948 assert(List->OnList == intptr_t(Lock), "invariant"); 4949 ParkEvent * const nxt = List->ListNext; 4950 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4951 4952 // The following CAS() releases the lock and pops the head element. 4953 // The CAS() also ratifies the previously fetched lock-word value. 4954 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4955 continue; 4956 } 4957 List->OnList = 0; 4958 OrderAccess::fence(); 4959 List->unpark(); 4960 return; 4961 } 4962 } 4963 4964 4965 void Threads::verify() { 4966 ALL_JAVA_THREADS(p) { 4967 p->verify(); 4968 } 4969 VMThread* thread = VMThread::vm_thread(); 4970 if (thread != NULL) thread->verify(); 4971 }