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/gcId.hpp" 37 #include "gc/shared/gcLocker.inline.hpp" 38 #include "gc/shared/workgroup.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "interpreter/linkResolver.hpp" 41 #include "interpreter/oopMapCache.hpp" 42 #include "jvmtifiles/jvmtiEnv.hpp" 43 #include "logging/log.hpp" 44 #include "logging/logConfiguration.hpp" 45 #include "logging/logStream.hpp" 46 #include "memory/allocation.inline.hpp" 47 #include "memory/metaspaceShared.hpp" 48 #include "memory/oopFactory.hpp" 49 #include "memory/resourceArea.hpp" 50 #include "memory/universe.hpp" 51 #include "oops/access.inline.hpp" 52 #include "oops/instanceKlass.hpp" 53 #include "oops/objArrayOop.hpp" 54 #include "oops/oop.inline.hpp" 55 #include "oops/symbol.hpp" 56 #include "oops/typeArrayOop.inline.hpp" 57 #include "oops/verifyOopClosure.hpp" 58 #include "prims/jvm_misc.hpp" 59 #include "prims/jvmtiExport.hpp" 60 #include "prims/jvmtiThreadState.hpp" 61 #include "prims/privilegedStack.hpp" 62 #include "runtime/arguments.hpp" 63 #include "runtime/atomic.hpp" 64 #include "runtime/biasedLocking.hpp" 65 #include "runtime/flags/jvmFlagConstraintList.hpp" 66 #include "runtime/flags/jvmFlagWriteableList.hpp" 67 #include "runtime/flags/jvmFlagRangeList.hpp" 68 #include "runtime/deoptimization.hpp" 69 #include "runtime/frame.inline.hpp" 70 #include "runtime/handshake.hpp" 71 #include "runtime/init.hpp" 72 #include "runtime/interfaceSupport.inline.hpp" 73 #include "runtime/java.hpp" 74 #include "runtime/javaCalls.hpp" 75 #include "runtime/jniHandles.inline.hpp" 76 #include "runtime/jniPeriodicChecker.hpp" 77 #include "runtime/memprofiler.hpp" 78 #include "runtime/mutexLocker.hpp" 79 #include "runtime/objectMonitor.hpp" 80 #include "runtime/orderAccess.inline.hpp" 81 #include "runtime/osThread.hpp" 82 #include "runtime/prefetch.inline.hpp" 83 #include "runtime/safepoint.hpp" 84 #include "runtime/safepointMechanism.inline.hpp" 85 #include "runtime/sharedRuntime.hpp" 86 #include "runtime/statSampler.hpp" 87 #include "runtime/stubRoutines.hpp" 88 #include "runtime/sweeper.hpp" 89 #include "runtime/task.hpp" 90 #include "runtime/thread.inline.hpp" 91 #include "runtime/threadCritical.hpp" 92 #include "runtime/threadSMR.inline.hpp" 93 #include "runtime/timer.hpp" 94 #include "runtime/timerTrace.hpp" 95 #include "runtime/vframe.inline.hpp" 96 #include "runtime/vframeArray.hpp" 97 #include "runtime/vframe_hp.hpp" 98 #include "runtime/vmThread.hpp" 99 #include "runtime/vm_operations.hpp" 100 #include "runtime/vm_version.hpp" 101 #include "services/attachListener.hpp" 102 #include "services/management.hpp" 103 #include "services/memTracker.hpp" 104 #include "services/threadService.hpp" 105 #include "trace/traceMacros.hpp" 106 #include "trace/tracing.hpp" 107 #include "utilities/align.hpp" 108 #include "utilities/defaultStream.hpp" 109 #include "utilities/dtrace.hpp" 110 #include "utilities/events.hpp" 111 #include "utilities/macros.hpp" 112 #include "utilities/preserveException.hpp" 113 #include "utilities/vmError.hpp" 114 #if INCLUDE_ALL_GCS 115 #include "gc/cms/concurrentMarkSweepThread.hpp" 116 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 117 #include "gc/parallel/pcTasks.hpp" 118 #endif // INCLUDE_ALL_GCS 119 #if INCLUDE_JVMCI 120 #include "jvmci/jvmciCompiler.hpp" 121 #include "jvmci/jvmciRuntime.hpp" 122 #include "logging/logHandle.hpp" 123 #endif 124 #ifdef COMPILER1 125 #include "c1/c1_Compiler.hpp" 126 #endif 127 #ifdef COMPILER2 128 #include "opto/c2compiler.hpp" 129 #include "opto/idealGraphPrinter.hpp" 130 #endif 131 #if INCLUDE_RTM_OPT 132 #include "runtime/rtmLocking.hpp" 133 #endif 134 135 // 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 _nested_threads_hazard_ptr = NULL; 244 _nested_threads_hazard_ptr_cnt = 0; 245 246 // the handle mark links itself to last_handle_mark 247 new HandleMark(this); 248 249 // plain initialization 250 debug_only(_owned_locks = NULL;) 251 debug_only(_allow_allocation_count = 0;) 252 NOT_PRODUCT(_allow_safepoint_count = 0;) 253 NOT_PRODUCT(_skip_gcalot = false;) 254 _jvmti_env_iteration_count = 0; 255 set_allocated_bytes(0); 256 _vm_operation_started_count = 0; 257 _vm_operation_completed_count = 0; 258 _current_pending_monitor = NULL; 259 _current_pending_monitor_is_from_java = true; 260 _current_waiting_monitor = NULL; 261 _num_nested_signal = 0; 262 omFreeList = NULL; 263 omFreeCount = 0; 264 omFreeProvision = 32; 265 omInUseList = NULL; 266 omInUseCount = 0; 267 268 #ifdef ASSERT 269 _visited_for_critical_count = false; 270 #endif 271 272 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 273 Monitor::_safepoint_check_sometimes); 274 _suspend_flags = 0; 275 276 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 277 _hashStateX = os::random(); 278 _hashStateY = 842502087; 279 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 280 _hashStateW = 273326509; 281 282 _OnTrap = 0; 283 _schedctl = NULL; 284 _Stalled = 0; 285 _TypeTag = 0x2BAD; 286 287 // Many of the following fields are effectively final - immutable 288 // Note that nascent threads can't use the Native Monitor-Mutex 289 // construct until the _MutexEvent is initialized ... 290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 291 // we might instead use a stack of ParkEvents that we could provision on-demand. 292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 293 // and ::Release() 294 _ParkEvent = ParkEvent::Allocate(this); 295 _SleepEvent = ParkEvent::Allocate(this); 296 _MutexEvent = ParkEvent::Allocate(this); 297 _MuxEvent = ParkEvent::Allocate(this); 298 299 #ifdef CHECK_UNHANDLED_OOPS 300 if (CheckUnhandledOops) { 301 _unhandled_oops = new UnhandledOops(this); 302 } 303 #endif // CHECK_UNHANDLED_OOPS 304 #ifdef ASSERT 305 if (UseBiasedLocking) { 306 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 307 assert(this == _real_malloc_address || 308 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 309 "bug in forced alignment of thread objects"); 310 } 311 #endif // ASSERT 312 } 313 314 void Thread::initialize_thread_current() { 315 #ifndef USE_LIBRARY_BASED_TLS_ONLY 316 assert(_thr_current == NULL, "Thread::current already initialized"); 317 _thr_current = this; 318 #endif 319 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 320 ThreadLocalStorage::set_thread(this); 321 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 322 } 323 324 void Thread::clear_thread_current() { 325 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 326 #ifndef USE_LIBRARY_BASED_TLS_ONLY 327 _thr_current = NULL; 328 #endif 329 ThreadLocalStorage::set_thread(NULL); 330 } 331 332 void Thread::record_stack_base_and_size() { 333 set_stack_base(os::current_stack_base()); 334 set_stack_size(os::current_stack_size()); 335 // CR 7190089: on Solaris, primordial thread's stack is adjusted 336 // in initialize_thread(). Without the adjustment, stack size is 337 // incorrect if stack is set to unlimited (ulimit -s unlimited). 338 // So far, only Solaris has real implementation of initialize_thread(). 339 // 340 // set up any platform-specific state. 341 os::initialize_thread(this); 342 343 // Set stack limits after thread is initialized. 344 if (is_Java_thread()) { 345 ((JavaThread*) this)->set_stack_overflow_limit(); 346 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 347 } 348 #if INCLUDE_NMT 349 // record thread's native stack, stack grows downward 350 MemTracker::record_thread_stack(stack_end(), stack_size()); 351 #endif // INCLUDE_NMT 352 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 353 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 354 os::current_thread_id(), p2i(stack_base() - stack_size()), 355 p2i(stack_base()), stack_size()/1024); 356 } 357 358 359 Thread::~Thread() { 360 EVENT_THREAD_DESTRUCT(this); 361 362 // stack_base can be NULL if the thread is never started or exited before 363 // record_stack_base_and_size called. Although, we would like to ensure 364 // that all started threads do call record_stack_base_and_size(), there is 365 // not proper way to enforce that. 366 #if INCLUDE_NMT 367 if (_stack_base != NULL) { 368 MemTracker::release_thread_stack(stack_end(), stack_size()); 369 #ifdef ASSERT 370 set_stack_base(NULL); 371 #endif 372 } 373 #endif // INCLUDE_NMT 374 375 // deallocate data structures 376 delete resource_area(); 377 // since the handle marks are using the handle area, we have to deallocated the root 378 // handle mark before deallocating the thread's handle area, 379 assert(last_handle_mark() != NULL, "check we have an element"); 380 delete last_handle_mark(); 381 assert(last_handle_mark() == NULL, "check we have reached the end"); 382 383 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 384 // We NULL out the fields for good hygiene. 385 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 386 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 387 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 388 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 389 390 delete handle_area(); 391 delete metadata_handles(); 392 393 // SR_handler uses this as a termination indicator - 394 // needs to happen before os::free_thread() 395 delete _SR_lock; 396 _SR_lock = NULL; 397 398 // osthread() can be NULL, if creation of thread failed. 399 if (osthread() != NULL) os::free_thread(osthread()); 400 401 // clear Thread::current if thread is deleting itself. 402 // Needed to ensure JNI correctly detects non-attached threads. 403 if (this == Thread::current()) { 404 clear_thread_current(); 405 } 406 407 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 408 } 409 410 // NOTE: dummy function for assertion purpose. 411 void Thread::run() { 412 ShouldNotReachHere(); 413 } 414 415 #ifdef ASSERT 416 // A JavaThread is considered "dangling" if it is not the current 417 // thread, has been added the Threads list, the system is not at a 418 // safepoint and the Thread is not "protected". 419 // 420 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 421 assert(!thread->is_Java_thread() || Thread::current() == thread || 422 !((JavaThread *) thread)->on_thread_list() || 423 SafepointSynchronize::is_at_safepoint() || 424 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 425 "possibility of dangling Thread pointer"); 426 } 427 #endif 428 429 ThreadPriority Thread::get_priority(const Thread* const thread) { 430 ThreadPriority priority; 431 // Can return an error! 432 (void)os::get_priority(thread, priority); 433 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 434 return priority; 435 } 436 437 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 438 debug_only(check_for_dangling_thread_pointer(thread);) 439 // Can return an error! 440 (void)os::set_priority(thread, priority); 441 } 442 443 444 void Thread::start(Thread* thread) { 445 // Start is different from resume in that its safety is guaranteed by context or 446 // being called from a Java method synchronized on the Thread object. 447 if (!DisableStartThread) { 448 if (thread->is_Java_thread()) { 449 // Initialize the thread state to RUNNABLE before starting this thread. 450 // Can not set it after the thread started because we do not know the 451 // exact thread state at that time. It could be in MONITOR_WAIT or 452 // in SLEEPING or some other state. 453 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 454 java_lang_Thread::RUNNABLE); 455 } 456 os::start_thread(thread); 457 } 458 } 459 460 // Enqueue a VM_Operation to do the job for us - sometime later 461 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 462 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 463 VMThread::execute(vm_stop); 464 } 465 466 467 // Check if an external suspend request has completed (or has been 468 // cancelled). Returns true if the thread is externally suspended and 469 // false otherwise. 470 // 471 // The bits parameter returns information about the code path through 472 // the routine. Useful for debugging: 473 // 474 // set in is_ext_suspend_completed(): 475 // 0x00000001 - routine was entered 476 // 0x00000010 - routine return false at end 477 // 0x00000100 - thread exited (return false) 478 // 0x00000200 - suspend request cancelled (return false) 479 // 0x00000400 - thread suspended (return true) 480 // 0x00001000 - thread is in a suspend equivalent state (return true) 481 // 0x00002000 - thread is native and walkable (return true) 482 // 0x00004000 - thread is native_trans and walkable (needed retry) 483 // 484 // set in wait_for_ext_suspend_completion(): 485 // 0x00010000 - routine was entered 486 // 0x00020000 - suspend request cancelled before loop (return false) 487 // 0x00040000 - thread suspended before loop (return true) 488 // 0x00080000 - suspend request cancelled in loop (return false) 489 // 0x00100000 - thread suspended in loop (return true) 490 // 0x00200000 - suspend not completed during retry loop (return false) 491 492 // Helper class for tracing suspend wait debug bits. 493 // 494 // 0x00000100 indicates that the target thread exited before it could 495 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 496 // 0x00080000 each indicate a cancelled suspend request so they don't 497 // count as wait failures either. 498 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 499 500 class TraceSuspendDebugBits : public StackObj { 501 private: 502 JavaThread * jt; 503 bool is_wait; 504 bool called_by_wait; // meaningful when !is_wait 505 uint32_t * bits; 506 507 public: 508 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 509 uint32_t *_bits) { 510 jt = _jt; 511 is_wait = _is_wait; 512 called_by_wait = _called_by_wait; 513 bits = _bits; 514 } 515 516 ~TraceSuspendDebugBits() { 517 if (!is_wait) { 518 #if 1 519 // By default, don't trace bits for is_ext_suspend_completed() calls. 520 // That trace is very chatty. 521 return; 522 #else 523 if (!called_by_wait) { 524 // If tracing for is_ext_suspend_completed() is enabled, then only 525 // trace calls to it from wait_for_ext_suspend_completion() 526 return; 527 } 528 #endif 529 } 530 531 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 532 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 533 MutexLocker ml(Threads_lock); // needed for get_thread_name() 534 ResourceMark rm; 535 536 tty->print_cr( 537 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 538 jt->get_thread_name(), *bits); 539 540 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 541 } 542 } 543 } 544 }; 545 #undef DEBUG_FALSE_BITS 546 547 548 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 549 uint32_t *bits) { 550 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 551 552 bool did_trans_retry = false; // only do thread_in_native_trans retry once 553 bool do_trans_retry; // flag to force the retry 554 555 *bits |= 0x00000001; 556 557 do { 558 do_trans_retry = false; 559 560 if (is_exiting()) { 561 // Thread is in the process of exiting. This is always checked 562 // first to reduce the risk of dereferencing a freed JavaThread. 563 *bits |= 0x00000100; 564 return false; 565 } 566 567 if (!is_external_suspend()) { 568 // Suspend request is cancelled. This is always checked before 569 // is_ext_suspended() to reduce the risk of a rogue resume 570 // confusing the thread that made the suspend request. 571 *bits |= 0x00000200; 572 return false; 573 } 574 575 if (is_ext_suspended()) { 576 // thread is suspended 577 *bits |= 0x00000400; 578 return true; 579 } 580 581 // Now that we no longer do hard suspends of threads running 582 // native code, the target thread can be changing thread state 583 // while we are in this routine: 584 // 585 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 586 // 587 // We save a copy of the thread state as observed at this moment 588 // and make our decision about suspend completeness based on the 589 // copy. This closes the race where the thread state is seen as 590 // _thread_in_native_trans in the if-thread_blocked check, but is 591 // seen as _thread_blocked in if-thread_in_native_trans check. 592 JavaThreadState save_state = thread_state(); 593 594 if (save_state == _thread_blocked && is_suspend_equivalent()) { 595 // If the thread's state is _thread_blocked and this blocking 596 // condition is known to be equivalent to a suspend, then we can 597 // consider the thread to be externally suspended. This means that 598 // the code that sets _thread_blocked has been modified to do 599 // self-suspension if the blocking condition releases. We also 600 // used to check for CONDVAR_WAIT here, but that is now covered by 601 // the _thread_blocked with self-suspension check. 602 // 603 // Return true since we wouldn't be here unless there was still an 604 // external suspend request. 605 *bits |= 0x00001000; 606 return true; 607 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 608 // Threads running native code will self-suspend on native==>VM/Java 609 // transitions. If its stack is walkable (should always be the case 610 // unless this function is called before the actual java_suspend() 611 // call), then the wait is done. 612 *bits |= 0x00002000; 613 return true; 614 } else if (!called_by_wait && !did_trans_retry && 615 save_state == _thread_in_native_trans && 616 frame_anchor()->walkable()) { 617 // The thread is transitioning from thread_in_native to another 618 // thread state. check_safepoint_and_suspend_for_native_trans() 619 // will force the thread to self-suspend. If it hasn't gotten 620 // there yet we may have caught the thread in-between the native 621 // code check above and the self-suspend. Lucky us. If we were 622 // called by wait_for_ext_suspend_completion(), then it 623 // will be doing the retries so we don't have to. 624 // 625 // Since we use the saved thread state in the if-statement above, 626 // there is a chance that the thread has already transitioned to 627 // _thread_blocked by the time we get here. In that case, we will 628 // make a single unnecessary pass through the logic below. This 629 // doesn't hurt anything since we still do the trans retry. 630 631 *bits |= 0x00004000; 632 633 // Once the thread leaves thread_in_native_trans for another 634 // thread state, we break out of this retry loop. We shouldn't 635 // need this flag to prevent us from getting back here, but 636 // sometimes paranoia is good. 637 did_trans_retry = true; 638 639 // We wait for the thread to transition to a more usable state. 640 for (int i = 1; i <= SuspendRetryCount; i++) { 641 // We used to do an "os::yield_all(i)" call here with the intention 642 // that yielding would increase on each retry. However, the parameter 643 // is ignored on Linux which means the yield didn't scale up. Waiting 644 // on the SR_lock below provides a much more predictable scale up for 645 // the delay. It also provides a simple/direct point to check for any 646 // safepoint requests from the VMThread 647 648 // temporarily drops SR_lock while doing wait with safepoint check 649 // (if we're a JavaThread - the WatcherThread can also call this) 650 // and increase delay with each retry 651 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 652 653 // check the actual thread state instead of what we saved above 654 if (thread_state() != _thread_in_native_trans) { 655 // the thread has transitioned to another thread state so 656 // try all the checks (except this one) one more time. 657 do_trans_retry = true; 658 break; 659 } 660 } // end retry loop 661 662 663 } 664 } while (do_trans_retry); 665 666 *bits |= 0x00000010; 667 return false; 668 } 669 670 // Wait for an external suspend request to complete (or be cancelled). 671 // Returns true if the thread is externally suspended and false otherwise. 672 // 673 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 674 uint32_t *bits) { 675 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 676 false /* !called_by_wait */, bits); 677 678 // local flag copies to minimize SR_lock hold time 679 bool is_suspended; 680 bool pending; 681 uint32_t reset_bits; 682 683 // set a marker so is_ext_suspend_completed() knows we are the caller 684 *bits |= 0x00010000; 685 686 // We use reset_bits to reinitialize the bits value at the top of 687 // each retry loop. This allows the caller to make use of any 688 // unused bits for their own marking purposes. 689 reset_bits = *bits; 690 691 { 692 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 693 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 694 delay, bits); 695 pending = is_external_suspend(); 696 } 697 // must release SR_lock to allow suspension to complete 698 699 if (!pending) { 700 // A cancelled suspend request is the only false return from 701 // is_ext_suspend_completed() that keeps us from entering the 702 // retry loop. 703 *bits |= 0x00020000; 704 return false; 705 } 706 707 if (is_suspended) { 708 *bits |= 0x00040000; 709 return true; 710 } 711 712 for (int i = 1; i <= retries; i++) { 713 *bits = reset_bits; // reinit to only track last retry 714 715 // We used to do an "os::yield_all(i)" call here with the intention 716 // that yielding would increase on each retry. However, the parameter 717 // is ignored on Linux which means the yield didn't scale up. Waiting 718 // on the SR_lock below provides a much more predictable scale up for 719 // the delay. It also provides a simple/direct point to check for any 720 // safepoint requests from the VMThread 721 722 { 723 MutexLocker ml(SR_lock()); 724 // wait with safepoint check (if we're a JavaThread - the WatcherThread 725 // can also call this) and increase delay with each retry 726 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 727 728 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 729 delay, bits); 730 731 // It is possible for the external suspend request to be cancelled 732 // (by a resume) before the actual suspend operation is completed. 733 // Refresh our local copy to see if we still need to wait. 734 pending = is_external_suspend(); 735 } 736 737 if (!pending) { 738 // A cancelled suspend request is the only false return from 739 // is_ext_suspend_completed() that keeps us from staying in the 740 // retry loop. 741 *bits |= 0x00080000; 742 return false; 743 } 744 745 if (is_suspended) { 746 *bits |= 0x00100000; 747 return true; 748 } 749 } // end retry loop 750 751 // thread did not suspend after all our retries 752 *bits |= 0x00200000; 753 return false; 754 } 755 756 // Called from API entry points which perform stack walking. If the 757 // associated JavaThread is the current thread, then wait_for_suspend 758 // is not used. Otherwise, it determines if we should wait for the 759 // "other" thread to complete external suspension. (NOTE: in future 760 // releases the suspension mechanism should be reimplemented so this 761 // is not necessary.) 762 // 763 bool 764 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 765 if (this != JavaThread::current()) { 766 // "other" threads require special handling. 767 if (wait_for_suspend) { 768 // We are allowed to wait for the external suspend to complete 769 // so give the other thread a chance to get suspended. 770 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 771 SuspendRetryDelay, bits)) { 772 // Didn't make it so let the caller know. 773 return false; 774 } 775 } 776 // We aren't allowed to wait for the external suspend to complete 777 // so if the other thread isn't externally suspended we need to 778 // let the caller know. 779 else if (!is_ext_suspend_completed_with_lock(bits)) { 780 return false; 781 } 782 } 783 784 return true; 785 } 786 787 #ifndef PRODUCT 788 void JavaThread::record_jump(address target, address instr, const char* file, 789 int line) { 790 791 // This should not need to be atomic as the only way for simultaneous 792 // updates is via interrupts. Even then this should be rare or non-existent 793 // and we don't care that much anyway. 794 795 int index = _jmp_ring_index; 796 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 797 _jmp_ring[index]._target = (intptr_t) target; 798 _jmp_ring[index]._instruction = (intptr_t) instr; 799 _jmp_ring[index]._file = file; 800 _jmp_ring[index]._line = line; 801 } 802 #endif // PRODUCT 803 804 void Thread::interrupt(Thread* thread) { 805 debug_only(check_for_dangling_thread_pointer(thread);) 806 os::interrupt(thread); 807 } 808 809 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 810 debug_only(check_for_dangling_thread_pointer(thread);) 811 // Note: If clear_interrupted==false, this simply fetches and 812 // returns the value of the field osthread()->interrupted(). 813 return os::is_interrupted(thread, clear_interrupted); 814 } 815 816 817 // GC Support 818 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 819 int thread_parity = _oops_do_parity; 820 if (thread_parity != strong_roots_parity) { 821 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 822 if (res == thread_parity) { 823 return true; 824 } else { 825 guarantee(res == strong_roots_parity, "Or else what?"); 826 return false; 827 } 828 } 829 return false; 830 } 831 832 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 833 active_handles()->oops_do(f); 834 // Do oop for ThreadShadow 835 f->do_oop((oop*)&_pending_exception); 836 handle_area()->oops_do(f); 837 838 if (MonitorInUseLists) { 839 // When using thread local monitor lists, we scan them here, 840 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 841 ObjectSynchronizer::thread_local_used_oops_do(this, f); 842 } 843 } 844 845 void Thread::metadata_handles_do(void f(Metadata*)) { 846 // Only walk the Handles in Thread. 847 if (metadata_handles() != NULL) { 848 for (int i = 0; i< metadata_handles()->length(); i++) { 849 f(metadata_handles()->at(i)); 850 } 851 } 852 } 853 854 void Thread::print_on(outputStream* st) const { 855 // get_priority assumes osthread initialized 856 if (osthread() != NULL) { 857 int os_prio; 858 if (os::get_native_priority(this, &os_prio) == OS_OK) { 859 st->print("os_prio=%d ", os_prio); 860 } 861 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 862 osthread()->print_on(st); 863 } 864 if (_threads_hazard_ptr != NULL) { 865 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 866 } 867 if (_nested_threads_hazard_ptr != NULL) { 868 print_nested_threads_hazard_ptrs_on(st); 869 } 870 st->print(" "); 871 debug_only(if (WizardMode) print_owned_locks_on(st);) 872 } 873 874 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const { 875 assert(_nested_threads_hazard_ptr != NULL, "must be set to print"); 876 877 if (EnableThreadSMRStatistics) { 878 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt); 879 } 880 st->print(", _nested_threads_hazard_ptrs="); 881 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL; 882 node = node->next()) { 883 if (node != _nested_threads_hazard_ptr) { 884 // First node does not need a comma-space separator. 885 st->print(", "); 886 } 887 st->print(INTPTR_FORMAT, p2i(node->t_list())); 888 } 889 } 890 891 // Thread::print_on_error() is called by fatal error handler. Don't use 892 // any lock or allocate memory. 893 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 894 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 895 896 if (is_VM_thread()) { st->print("VMThread"); } 897 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 898 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 899 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 900 else { st->print("Thread"); } 901 902 if (is_Named_thread()) { 903 st->print(" \"%s\"", name()); 904 } 905 906 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 907 p2i(stack_end()), p2i(stack_base())); 908 909 if (osthread()) { 910 st->print(" [id=%d]", osthread()->thread_id()); 911 } 912 913 if (_threads_hazard_ptr != NULL) { 914 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 915 } 916 if (_nested_threads_hazard_ptr != NULL) { 917 print_nested_threads_hazard_ptrs_on(st); 918 } 919 } 920 921 void Thread::print_value_on(outputStream* st) const { 922 if (is_Named_thread()) { 923 st->print(" \"%s\" ", name()); 924 } 925 st->print(INTPTR_FORMAT, p2i(this)); // print address 926 } 927 928 #ifdef ASSERT 929 void Thread::print_owned_locks_on(outputStream* st) const { 930 Monitor *cur = _owned_locks; 931 if (cur == NULL) { 932 st->print(" (no locks) "); 933 } else { 934 st->print_cr(" Locks owned:"); 935 while (cur) { 936 cur->print_on(st); 937 cur = cur->next(); 938 } 939 } 940 } 941 942 static int ref_use_count = 0; 943 944 bool Thread::owns_locks_but_compiled_lock() const { 945 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 946 if (cur != Compile_lock) return true; 947 } 948 return false; 949 } 950 951 952 #endif 953 954 #ifndef PRODUCT 955 956 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 957 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 958 // no threads which allow_vm_block's are held 959 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 960 // Check if current thread is allowed to block at a safepoint 961 if (!(_allow_safepoint_count == 0)) { 962 fatal("Possible safepoint reached by thread that does not allow it"); 963 } 964 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 965 fatal("LEAF method calling lock?"); 966 } 967 968 #ifdef ASSERT 969 if (potential_vm_operation && is_Java_thread() 970 && !Universe::is_bootstrapping()) { 971 // Make sure we do not hold any locks that the VM thread also uses. 972 // This could potentially lead to deadlocks 973 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 974 // Threads_lock is special, since the safepoint synchronization will not start before this is 975 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 976 // since it is used to transfer control between JavaThreads and the VMThread 977 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 978 if ((cur->allow_vm_block() && 979 cur != Threads_lock && 980 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 981 cur != VMOperationRequest_lock && 982 cur != VMOperationQueue_lock) || 983 cur->rank() == Mutex::special) { 984 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 985 } 986 } 987 } 988 989 if (GCALotAtAllSafepoints) { 990 // We could enter a safepoint here and thus have a gc 991 InterfaceSupport::check_gc_alot(); 992 } 993 #endif 994 } 995 #endif 996 997 bool Thread::is_in_stack(address adr) const { 998 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 999 address end = os::current_stack_pointer(); 1000 // Allow non Java threads to call this without stack_base 1001 if (_stack_base == NULL) return true; 1002 if (stack_base() >= adr && adr >= end) return true; 1003 1004 return false; 1005 } 1006 1007 bool Thread::is_in_usable_stack(address adr) const { 1008 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1009 size_t usable_stack_size = _stack_size - stack_guard_size; 1010 1011 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1012 } 1013 1014 1015 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1016 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1017 // used for compilation in the future. If that change is made, the need for these methods 1018 // should be revisited, and they should be removed if possible. 1019 1020 bool Thread::is_lock_owned(address adr) const { 1021 return on_local_stack(adr); 1022 } 1023 1024 bool Thread::set_as_starting_thread() { 1025 // NOTE: this must be called inside the main thread. 1026 return os::create_main_thread((JavaThread*)this); 1027 } 1028 1029 static void initialize_class(Symbol* class_name, TRAPS) { 1030 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1031 InstanceKlass::cast(klass)->initialize(CHECK); 1032 } 1033 1034 1035 // Creates the initial ThreadGroup 1036 static Handle create_initial_thread_group(TRAPS) { 1037 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 1038 InstanceKlass* ik = InstanceKlass::cast(k); 1039 1040 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 1041 { 1042 JavaValue result(T_VOID); 1043 JavaCalls::call_special(&result, 1044 system_instance, 1045 ik, 1046 vmSymbols::object_initializer_name(), 1047 vmSymbols::void_method_signature(), 1048 CHECK_NH); 1049 } 1050 Universe::set_system_thread_group(system_instance()); 1051 1052 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 1053 { 1054 JavaValue result(T_VOID); 1055 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1056 JavaCalls::call_special(&result, 1057 main_instance, 1058 ik, 1059 vmSymbols::object_initializer_name(), 1060 vmSymbols::threadgroup_string_void_signature(), 1061 system_instance, 1062 string, 1063 CHECK_NH); 1064 } 1065 return main_instance; 1066 } 1067 1068 // Creates the initial Thread 1069 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1070 TRAPS) { 1071 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1072 InstanceKlass* ik = InstanceKlass::cast(k); 1073 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1074 1075 java_lang_Thread::set_thread(thread_oop(), thread); 1076 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1077 thread->set_threadObj(thread_oop()); 1078 1079 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1080 1081 JavaValue result(T_VOID); 1082 JavaCalls::call_special(&result, thread_oop, 1083 ik, 1084 vmSymbols::object_initializer_name(), 1085 vmSymbols::threadgroup_string_void_signature(), 1086 thread_group, 1087 string, 1088 CHECK_NULL); 1089 return thread_oop(); 1090 } 1091 1092 char java_runtime_name[128] = ""; 1093 char java_runtime_version[128] = ""; 1094 1095 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1096 static const char* get_java_runtime_name(TRAPS) { 1097 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1098 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1099 fieldDescriptor fd; 1100 bool found = k != NULL && 1101 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1102 vmSymbols::string_signature(), &fd); 1103 if (found) { 1104 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1105 if (name_oop == NULL) { 1106 return NULL; 1107 } 1108 const char* name = java_lang_String::as_utf8_string(name_oop, 1109 java_runtime_name, 1110 sizeof(java_runtime_name)); 1111 return name; 1112 } else { 1113 return NULL; 1114 } 1115 } 1116 1117 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1118 static const char* get_java_runtime_version(TRAPS) { 1119 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1120 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1121 fieldDescriptor fd; 1122 bool found = k != NULL && 1123 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1124 vmSymbols::string_signature(), &fd); 1125 if (found) { 1126 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1127 if (name_oop == NULL) { 1128 return NULL; 1129 } 1130 const char* name = java_lang_String::as_utf8_string(name_oop, 1131 java_runtime_version, 1132 sizeof(java_runtime_version)); 1133 return name; 1134 } else { 1135 return NULL; 1136 } 1137 } 1138 1139 // General purpose hook into Java code, run once when the VM is initialized. 1140 // The Java library method itself may be changed independently from the VM. 1141 static void call_postVMInitHook(TRAPS) { 1142 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1143 if (klass != NULL) { 1144 JavaValue result(T_VOID); 1145 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1146 vmSymbols::void_method_signature(), 1147 CHECK); 1148 } 1149 } 1150 1151 static void reset_vm_info_property(TRAPS) { 1152 // the vm info string 1153 ResourceMark rm(THREAD); 1154 const char *vm_info = VM_Version::vm_info_string(); 1155 1156 // java.lang.System class 1157 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1158 1159 // setProperty arguments 1160 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1161 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1162 1163 // return value 1164 JavaValue r(T_OBJECT); 1165 1166 // public static String setProperty(String key, String value); 1167 JavaCalls::call_static(&r, 1168 klass, 1169 vmSymbols::setProperty_name(), 1170 vmSymbols::string_string_string_signature(), 1171 key_str, 1172 value_str, 1173 CHECK); 1174 } 1175 1176 1177 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1178 bool daemon, TRAPS) { 1179 assert(thread_group.not_null(), "thread group should be specified"); 1180 assert(threadObj() == NULL, "should only create Java thread object once"); 1181 1182 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1183 InstanceKlass* ik = InstanceKlass::cast(k); 1184 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1185 1186 java_lang_Thread::set_thread(thread_oop(), this); 1187 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1188 set_threadObj(thread_oop()); 1189 1190 JavaValue result(T_VOID); 1191 if (thread_name != NULL) { 1192 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1193 // Thread gets assigned specified name and null target 1194 JavaCalls::call_special(&result, 1195 thread_oop, 1196 ik, 1197 vmSymbols::object_initializer_name(), 1198 vmSymbols::threadgroup_string_void_signature(), 1199 thread_group, // Argument 1 1200 name, // Argument 2 1201 THREAD); 1202 } else { 1203 // Thread gets assigned name "Thread-nnn" and null target 1204 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1205 JavaCalls::call_special(&result, 1206 thread_oop, 1207 ik, 1208 vmSymbols::object_initializer_name(), 1209 vmSymbols::threadgroup_runnable_void_signature(), 1210 thread_group, // Argument 1 1211 Handle(), // Argument 2 1212 THREAD); 1213 } 1214 1215 1216 if (daemon) { 1217 java_lang_Thread::set_daemon(thread_oop()); 1218 } 1219 1220 if (HAS_PENDING_EXCEPTION) { 1221 return; 1222 } 1223 1224 Klass* group = SystemDictionary::ThreadGroup_klass(); 1225 Handle threadObj(THREAD, this->threadObj()); 1226 1227 JavaCalls::call_special(&result, 1228 thread_group, 1229 group, 1230 vmSymbols::add_method_name(), 1231 vmSymbols::thread_void_signature(), 1232 threadObj, // Arg 1 1233 THREAD); 1234 } 1235 1236 // NamedThread -- non-JavaThread subclasses with multiple 1237 // uniquely named instances should derive from this. 1238 NamedThread::NamedThread() : Thread() { 1239 _name = NULL; 1240 _processed_thread = NULL; 1241 _gc_id = GCId::undefined(); 1242 } 1243 1244 NamedThread::~NamedThread() { 1245 if (_name != NULL) { 1246 FREE_C_HEAP_ARRAY(char, _name); 1247 _name = NULL; 1248 } 1249 } 1250 1251 void NamedThread::set_name(const char* format, ...) { 1252 guarantee(_name == NULL, "Only get to set name once."); 1253 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1254 guarantee(_name != NULL, "alloc failure"); 1255 va_list ap; 1256 va_start(ap, format); 1257 jio_vsnprintf(_name, max_name_len, format, ap); 1258 va_end(ap); 1259 } 1260 1261 void NamedThread::initialize_named_thread() { 1262 set_native_thread_name(name()); 1263 } 1264 1265 void NamedThread::print_on(outputStream* st) const { 1266 st->print("\"%s\" ", name()); 1267 Thread::print_on(st); 1268 st->cr(); 1269 } 1270 1271 1272 // ======= WatcherThread ======== 1273 1274 // The watcher thread exists to simulate timer interrupts. It should 1275 // be replaced by an abstraction over whatever native support for 1276 // timer interrupts exists on the platform. 1277 1278 WatcherThread* WatcherThread::_watcher_thread = NULL; 1279 bool WatcherThread::_startable = false; 1280 volatile bool WatcherThread::_should_terminate = false; 1281 1282 WatcherThread::WatcherThread() : Thread() { 1283 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1284 if (os::create_thread(this, os::watcher_thread)) { 1285 _watcher_thread = this; 1286 1287 // Set the watcher thread to the highest OS priority which should not be 1288 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1289 // is created. The only normal thread using this priority is the reference 1290 // handler thread, which runs for very short intervals only. 1291 // If the VMThread's priority is not lower than the WatcherThread profiling 1292 // will be inaccurate. 1293 os::set_priority(this, MaxPriority); 1294 if (!DisableStartThread) { 1295 os::start_thread(this); 1296 } 1297 } 1298 } 1299 1300 int WatcherThread::sleep() const { 1301 // The WatcherThread does not participate in the safepoint protocol 1302 // for the PeriodicTask_lock because it is not a JavaThread. 1303 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1304 1305 if (_should_terminate) { 1306 // check for termination before we do any housekeeping or wait 1307 return 0; // we did not sleep. 1308 } 1309 1310 // remaining will be zero if there are no tasks, 1311 // causing the WatcherThread to sleep until a task is 1312 // enrolled 1313 int remaining = PeriodicTask::time_to_wait(); 1314 int time_slept = 0; 1315 1316 // we expect this to timeout - we only ever get unparked when 1317 // we should terminate or when a new task has been enrolled 1318 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1319 1320 jlong time_before_loop = os::javaTimeNanos(); 1321 1322 while (true) { 1323 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1324 remaining); 1325 jlong now = os::javaTimeNanos(); 1326 1327 if (remaining == 0) { 1328 // if we didn't have any tasks we could have waited for a long time 1329 // consider the time_slept zero and reset time_before_loop 1330 time_slept = 0; 1331 time_before_loop = now; 1332 } else { 1333 // need to recalculate since we might have new tasks in _tasks 1334 time_slept = (int) ((now - time_before_loop) / 1000000); 1335 } 1336 1337 // Change to task list or spurious wakeup of some kind 1338 if (timedout || _should_terminate) { 1339 break; 1340 } 1341 1342 remaining = PeriodicTask::time_to_wait(); 1343 if (remaining == 0) { 1344 // Last task was just disenrolled so loop around and wait until 1345 // another task gets enrolled 1346 continue; 1347 } 1348 1349 remaining -= time_slept; 1350 if (remaining <= 0) { 1351 break; 1352 } 1353 } 1354 1355 return time_slept; 1356 } 1357 1358 void WatcherThread::run() { 1359 assert(this == watcher_thread(), "just checking"); 1360 1361 this->record_stack_base_and_size(); 1362 this->set_native_thread_name(this->name()); 1363 this->set_active_handles(JNIHandleBlock::allocate_block()); 1364 while (true) { 1365 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1366 assert(watcher_thread() == this, "thread consistency check"); 1367 1368 // Calculate how long it'll be until the next PeriodicTask work 1369 // should be done, and sleep that amount of time. 1370 int time_waited = sleep(); 1371 1372 if (VMError::is_error_reported()) { 1373 // A fatal error has happened, the error handler(VMError::report_and_die) 1374 // should abort JVM after creating an error log file. However in some 1375 // rare cases, the error handler itself might deadlock. Here periodically 1376 // check for error reporting timeouts, and if it happens, just proceed to 1377 // abort the VM. 1378 1379 // This code is in WatcherThread because WatcherThread wakes up 1380 // periodically so the fatal error handler doesn't need to do anything; 1381 // also because the WatcherThread is less likely to crash than other 1382 // threads. 1383 1384 for (;;) { 1385 // Note: we use naked sleep in this loop because we want to avoid using 1386 // any kind of VM infrastructure which may be broken at this point. 1387 if (VMError::check_timeout()) { 1388 // We hit error reporting timeout. Error reporting was interrupted and 1389 // will be wrapping things up now (closing files etc). Give it some more 1390 // time, then quit the VM. 1391 os::naked_short_sleep(200); 1392 // Print a message to stderr. 1393 fdStream err(defaultStream::output_fd()); 1394 err.print_raw_cr("# [ timer expired, abort... ]"); 1395 // skip atexit/vm_exit/vm_abort hooks 1396 os::die(); 1397 } 1398 1399 // Wait a second, then recheck for timeout. 1400 os::naked_short_sleep(999); 1401 } 1402 } 1403 1404 if (_should_terminate) { 1405 // check for termination before posting the next tick 1406 break; 1407 } 1408 1409 PeriodicTask::real_time_tick(time_waited); 1410 } 1411 1412 // Signal that it is terminated 1413 { 1414 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1415 _watcher_thread = NULL; 1416 Terminator_lock->notify(); 1417 } 1418 } 1419 1420 void WatcherThread::start() { 1421 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1422 1423 if (watcher_thread() == NULL && _startable) { 1424 _should_terminate = false; 1425 // Create the single instance of WatcherThread 1426 new WatcherThread(); 1427 } 1428 } 1429 1430 void WatcherThread::make_startable() { 1431 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1432 _startable = true; 1433 } 1434 1435 void WatcherThread::stop() { 1436 { 1437 // Follow normal safepoint aware lock enter protocol since the 1438 // WatcherThread is stopped by another JavaThread. 1439 MutexLocker ml(PeriodicTask_lock); 1440 _should_terminate = true; 1441 1442 WatcherThread* watcher = watcher_thread(); 1443 if (watcher != NULL) { 1444 // unpark the WatcherThread so it can see that it should terminate 1445 watcher->unpark(); 1446 } 1447 } 1448 1449 MutexLocker mu(Terminator_lock); 1450 1451 while (watcher_thread() != NULL) { 1452 // This wait should make safepoint checks, wait without a timeout, 1453 // and wait as a suspend-equivalent condition. 1454 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1455 Mutex::_as_suspend_equivalent_flag); 1456 } 1457 } 1458 1459 void WatcherThread::unpark() { 1460 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1461 PeriodicTask_lock->notify(); 1462 } 1463 1464 void WatcherThread::print_on(outputStream* st) const { 1465 st->print("\"%s\" ", name()); 1466 Thread::print_on(st); 1467 st->cr(); 1468 } 1469 1470 // ======= JavaThread ======== 1471 1472 #if INCLUDE_JVMCI 1473 1474 jlong* JavaThread::_jvmci_old_thread_counters; 1475 1476 bool jvmci_counters_include(JavaThread* thread) { 1477 oop threadObj = thread->threadObj(); 1478 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1479 } 1480 1481 void JavaThread::collect_counters(typeArrayOop array) { 1482 if (JVMCICounterSize > 0) { 1483 MutexLocker tl(Threads_lock); 1484 JavaThreadIteratorWithHandle jtiwh; 1485 for (int i = 0; i < array->length(); i++) { 1486 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1487 } 1488 for (; JavaThread *tp = jtiwh.next(); ) { 1489 if (jvmci_counters_include(tp)) { 1490 for (int i = 0; i < array->length(); i++) { 1491 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1492 } 1493 } 1494 } 1495 } 1496 } 1497 1498 #endif // INCLUDE_JVMCI 1499 1500 // A JavaThread is a normal Java thread 1501 1502 void JavaThread::initialize() { 1503 // Initialize fields 1504 1505 set_saved_exception_pc(NULL); 1506 set_threadObj(NULL); 1507 _anchor.clear(); 1508 set_entry_point(NULL); 1509 set_jni_functions(jni_functions()); 1510 set_callee_target(NULL); 1511 set_vm_result(NULL); 1512 set_vm_result_2(NULL); 1513 set_vframe_array_head(NULL); 1514 set_vframe_array_last(NULL); 1515 set_deferred_locals(NULL); 1516 set_deopt_mark(NULL); 1517 set_deopt_compiled_method(NULL); 1518 clear_must_deopt_id(); 1519 set_monitor_chunks(NULL); 1520 set_next(NULL); 1521 _on_thread_list = false; 1522 set_thread_state(_thread_new); 1523 _terminated = _not_terminated; 1524 _privileged_stack_top = NULL; 1525 _array_for_gc = NULL; 1526 _suspend_equivalent = false; 1527 _in_deopt_handler = 0; 1528 _doing_unsafe_access = false; 1529 _stack_guard_state = stack_guard_unused; 1530 #if INCLUDE_JVMCI 1531 _pending_monitorenter = false; 1532 _pending_deoptimization = -1; 1533 _pending_failed_speculation = NULL; 1534 _pending_transfer_to_interpreter = false; 1535 _adjusting_comp_level = false; 1536 _jvmci._alternate_call_target = NULL; 1537 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1538 if (JVMCICounterSize > 0) { 1539 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1540 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1541 } else { 1542 _jvmci_counters = NULL; 1543 } 1544 #endif // INCLUDE_JVMCI 1545 _reserved_stack_activation = NULL; // stack base not known yet 1546 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1547 _exception_pc = 0; 1548 _exception_handler_pc = 0; 1549 _is_method_handle_return = 0; 1550 _jvmti_thread_state= NULL; 1551 _should_post_on_exceptions_flag = JNI_FALSE; 1552 _jvmti_get_loaded_classes_closure = NULL; 1553 _interp_only_mode = 0; 1554 _special_runtime_exit_condition = _no_async_condition; 1555 _pending_async_exception = NULL; 1556 _thread_stat = NULL; 1557 _thread_stat = new ThreadStatistics(); 1558 _blocked_on_compilation = false; 1559 _jni_active_critical = 0; 1560 _pending_jni_exception_check_fn = NULL; 1561 _do_not_unlock_if_synchronized = false; 1562 _cached_monitor_info = NULL; 1563 _parker = Parker::Allocate(this); 1564 1565 #ifndef PRODUCT 1566 _jmp_ring_index = 0; 1567 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1568 record_jump(NULL, NULL, NULL, 0); 1569 } 1570 #endif // PRODUCT 1571 1572 // Setup safepoint state info for this thread 1573 ThreadSafepointState::create(this); 1574 1575 debug_only(_java_call_counter = 0); 1576 1577 // JVMTI PopFrame support 1578 _popframe_condition = popframe_inactive; 1579 _popframe_preserved_args = NULL; 1580 _popframe_preserved_args_size = 0; 1581 _frames_to_pop_failed_realloc = 0; 1582 1583 if (SafepointMechanism::uses_thread_local_poll()) { 1584 SafepointMechanism::initialize_header(this); 1585 } 1586 1587 pd_initialize(); 1588 } 1589 1590 #if INCLUDE_ALL_GCS 1591 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1592 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1593 #endif // INCLUDE_ALL_GCS 1594 1595 JavaThread::JavaThread(bool is_attaching_via_jni) : 1596 Thread() 1597 #if INCLUDE_ALL_GCS 1598 , _satb_mark_queue(&_satb_mark_queue_set), 1599 _dirty_card_queue(&_dirty_card_queue_set) 1600 #endif // INCLUDE_ALL_GCS 1601 { 1602 initialize(); 1603 if (is_attaching_via_jni) { 1604 _jni_attach_state = _attaching_via_jni; 1605 } else { 1606 _jni_attach_state = _not_attaching_via_jni; 1607 } 1608 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1609 } 1610 1611 bool JavaThread::reguard_stack(address cur_sp) { 1612 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1613 && _stack_guard_state != stack_guard_reserved_disabled) { 1614 return true; // Stack already guarded or guard pages not needed. 1615 } 1616 1617 if (register_stack_overflow()) { 1618 // For those architectures which have separate register and 1619 // memory stacks, we must check the register stack to see if 1620 // it has overflowed. 1621 return false; 1622 } 1623 1624 // Java code never executes within the yellow zone: the latter is only 1625 // there to provoke an exception during stack banging. If java code 1626 // is executing there, either StackShadowPages should be larger, or 1627 // some exception code in c1, c2 or the interpreter isn't unwinding 1628 // when it should. 1629 guarantee(cur_sp > stack_reserved_zone_base(), 1630 "not enough space to reguard - increase StackShadowPages"); 1631 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1632 enable_stack_yellow_reserved_zone(); 1633 if (reserved_stack_activation() != stack_base()) { 1634 set_reserved_stack_activation(stack_base()); 1635 } 1636 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1637 set_reserved_stack_activation(stack_base()); 1638 enable_stack_reserved_zone(); 1639 } 1640 return true; 1641 } 1642 1643 bool JavaThread::reguard_stack(void) { 1644 return reguard_stack(os::current_stack_pointer()); 1645 } 1646 1647 1648 void JavaThread::block_if_vm_exited() { 1649 if (_terminated == _vm_exited) { 1650 // _vm_exited is set at safepoint, and Threads_lock is never released 1651 // we will block here forever 1652 Threads_lock->lock_without_safepoint_check(); 1653 ShouldNotReachHere(); 1654 } 1655 } 1656 1657 1658 // Remove this ifdef when C1 is ported to the compiler interface. 1659 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1660 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1661 1662 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1663 Thread() 1664 #if INCLUDE_ALL_GCS 1665 , _satb_mark_queue(&_satb_mark_queue_set), 1666 _dirty_card_queue(&_dirty_card_queue_set) 1667 #endif // INCLUDE_ALL_GCS 1668 { 1669 initialize(); 1670 _jni_attach_state = _not_attaching_via_jni; 1671 set_entry_point(entry_point); 1672 // Create the native thread itself. 1673 // %note runtime_23 1674 os::ThreadType thr_type = os::java_thread; 1675 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1676 os::java_thread; 1677 os::create_thread(this, thr_type, stack_sz); 1678 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1679 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1680 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1681 // the exception consists of creating the exception object & initializing it, initialization 1682 // will leave the VM via a JavaCall and then all locks must be unlocked). 1683 // 1684 // The thread is still suspended when we reach here. Thread must be explicit started 1685 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1686 // by calling Threads:add. The reason why this is not done here, is because the thread 1687 // object must be fully initialized (take a look at JVM_Start) 1688 } 1689 1690 JavaThread::~JavaThread() { 1691 1692 // JSR166 -- return the parker to the free list 1693 Parker::Release(_parker); 1694 _parker = NULL; 1695 1696 // Free any remaining previous UnrollBlock 1697 vframeArray* old_array = vframe_array_last(); 1698 1699 if (old_array != NULL) { 1700 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1701 old_array->set_unroll_block(NULL); 1702 delete old_info; 1703 delete old_array; 1704 } 1705 1706 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1707 if (deferred != NULL) { 1708 // This can only happen if thread is destroyed before deoptimization occurs. 1709 assert(deferred->length() != 0, "empty array!"); 1710 do { 1711 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1712 deferred->remove_at(0); 1713 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1714 delete dlv; 1715 } while (deferred->length() != 0); 1716 delete deferred; 1717 } 1718 1719 // All Java related clean up happens in exit 1720 ThreadSafepointState::destroy(this); 1721 if (_thread_stat != NULL) delete _thread_stat; 1722 1723 #if INCLUDE_JVMCI 1724 if (JVMCICounterSize > 0) { 1725 if (jvmci_counters_include(this)) { 1726 for (int i = 0; i < JVMCICounterSize; i++) { 1727 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1728 } 1729 } 1730 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1731 } 1732 #endif // INCLUDE_JVMCI 1733 } 1734 1735 1736 // The first routine called by a new Java thread 1737 void JavaThread::run() { 1738 // initialize thread-local alloc buffer related fields 1739 this->initialize_tlab(); 1740 1741 // used to test validity of stack trace backs 1742 this->record_base_of_stack_pointer(); 1743 1744 // Record real stack base and size. 1745 this->record_stack_base_and_size(); 1746 1747 this->create_stack_guard_pages(); 1748 1749 this->cache_global_variables(); 1750 1751 // Thread is now sufficient initialized to be handled by the safepoint code as being 1752 // in the VM. Change thread state from _thread_new to _thread_in_vm 1753 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1754 1755 assert(JavaThread::current() == this, "sanity check"); 1756 assert(!Thread::current()->owns_locks(), "sanity check"); 1757 1758 DTRACE_THREAD_PROBE(start, this); 1759 1760 // This operation might block. We call that after all safepoint checks for a new thread has 1761 // been completed. 1762 this->set_active_handles(JNIHandleBlock::allocate_block()); 1763 1764 if (JvmtiExport::should_post_thread_life()) { 1765 JvmtiExport::post_thread_start(this); 1766 } 1767 1768 EventThreadStart event; 1769 if (event.should_commit()) { 1770 event.set_thread(THREAD_TRACE_ID(this)); 1771 event.commit(); 1772 } 1773 1774 // We call another function to do the rest so we are sure that the stack addresses used 1775 // from there will be lower than the stack base just computed 1776 thread_main_inner(); 1777 1778 // Note, thread is no longer valid at this point! 1779 } 1780 1781 1782 void JavaThread::thread_main_inner() { 1783 assert(JavaThread::current() == this, "sanity check"); 1784 assert(this->threadObj() != NULL, "just checking"); 1785 1786 // Execute thread entry point unless this thread has a pending exception 1787 // or has been stopped before starting. 1788 // Note: Due to JVM_StopThread we can have pending exceptions already! 1789 if (!this->has_pending_exception() && 1790 !java_lang_Thread::is_stillborn(this->threadObj())) { 1791 { 1792 ResourceMark rm(this); 1793 this->set_native_thread_name(this->get_thread_name()); 1794 } 1795 HandleMark hm(this); 1796 this->entry_point()(this, this); 1797 } 1798 1799 DTRACE_THREAD_PROBE(stop, this); 1800 1801 this->exit(false); 1802 this->smr_delete(); 1803 } 1804 1805 1806 static void ensure_join(JavaThread* thread) { 1807 // We do not need to grab the Threads_lock, since we are operating on ourself. 1808 Handle threadObj(thread, thread->threadObj()); 1809 assert(threadObj.not_null(), "java thread object must exist"); 1810 ObjectLocker lock(threadObj, thread); 1811 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1812 thread->clear_pending_exception(); 1813 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1814 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1815 // Clear the native thread instance - this makes isAlive return false and allows the join() 1816 // to complete once we've done the notify_all below 1817 java_lang_Thread::set_thread(threadObj(), NULL); 1818 lock.notify_all(thread); 1819 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1820 thread->clear_pending_exception(); 1821 } 1822 1823 1824 // For any new cleanup additions, please check to see if they need to be applied to 1825 // cleanup_failed_attach_current_thread as well. 1826 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1827 assert(this == JavaThread::current(), "thread consistency check"); 1828 1829 elapsedTimer _timer_exit_phase1; 1830 elapsedTimer _timer_exit_phase2; 1831 elapsedTimer _timer_exit_phase3; 1832 elapsedTimer _timer_exit_phase4; 1833 1834 if (log_is_enabled(Debug, os, thread, timer)) { 1835 _timer_exit_phase1.start(); 1836 } 1837 1838 HandleMark hm(this); 1839 Handle uncaught_exception(this, this->pending_exception()); 1840 this->clear_pending_exception(); 1841 Handle threadObj(this, this->threadObj()); 1842 assert(threadObj.not_null(), "Java thread object should be created"); 1843 1844 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1845 { 1846 EXCEPTION_MARK; 1847 1848 CLEAR_PENDING_EXCEPTION; 1849 } 1850 if (!destroy_vm) { 1851 if (uncaught_exception.not_null()) { 1852 EXCEPTION_MARK; 1853 // Call method Thread.dispatchUncaughtException(). 1854 Klass* thread_klass = SystemDictionary::Thread_klass(); 1855 JavaValue result(T_VOID); 1856 JavaCalls::call_virtual(&result, 1857 threadObj, thread_klass, 1858 vmSymbols::dispatchUncaughtException_name(), 1859 vmSymbols::throwable_void_signature(), 1860 uncaught_exception, 1861 THREAD); 1862 if (HAS_PENDING_EXCEPTION) { 1863 ResourceMark rm(this); 1864 jio_fprintf(defaultStream::error_stream(), 1865 "\nException: %s thrown from the UncaughtExceptionHandler" 1866 " in thread \"%s\"\n", 1867 pending_exception()->klass()->external_name(), 1868 get_thread_name()); 1869 CLEAR_PENDING_EXCEPTION; 1870 } 1871 } 1872 1873 // Called before the java thread exit since we want to read info 1874 // from java_lang_Thread object 1875 EventThreadEnd event; 1876 if (event.should_commit()) { 1877 event.set_thread(THREAD_TRACE_ID(this)); 1878 event.commit(); 1879 } 1880 1881 // Call after last event on thread 1882 EVENT_THREAD_EXIT(this); 1883 1884 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1885 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1886 // is deprecated anyhow. 1887 if (!is_Compiler_thread()) { 1888 int count = 3; 1889 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1890 EXCEPTION_MARK; 1891 JavaValue result(T_VOID); 1892 Klass* thread_klass = SystemDictionary::Thread_klass(); 1893 JavaCalls::call_virtual(&result, 1894 threadObj, thread_klass, 1895 vmSymbols::exit_method_name(), 1896 vmSymbols::void_method_signature(), 1897 THREAD); 1898 CLEAR_PENDING_EXCEPTION; 1899 } 1900 } 1901 // notify JVMTI 1902 if (JvmtiExport::should_post_thread_life()) { 1903 JvmtiExport::post_thread_end(this); 1904 } 1905 1906 // We have notified the agents that we are exiting, before we go on, 1907 // we must check for a pending external suspend request and honor it 1908 // in order to not surprise the thread that made the suspend request. 1909 while (true) { 1910 { 1911 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1912 if (!is_external_suspend()) { 1913 set_terminated(_thread_exiting); 1914 ThreadService::current_thread_exiting(this); 1915 break; 1916 } 1917 // Implied else: 1918 // Things get a little tricky here. We have a pending external 1919 // suspend request, but we are holding the SR_lock so we 1920 // can't just self-suspend. So we temporarily drop the lock 1921 // and then self-suspend. 1922 } 1923 1924 ThreadBlockInVM tbivm(this); 1925 java_suspend_self(); 1926 1927 // We're done with this suspend request, but we have to loop around 1928 // and check again. Eventually we will get SR_lock without a pending 1929 // external suspend request and will be able to mark ourselves as 1930 // exiting. 1931 } 1932 // no more external suspends are allowed at this point 1933 } else { 1934 // before_exit() has already posted JVMTI THREAD_END events 1935 } 1936 1937 if (log_is_enabled(Debug, os, thread, timer)) { 1938 _timer_exit_phase1.stop(); 1939 _timer_exit_phase2.start(); 1940 } 1941 // Notify waiters on thread object. This has to be done after exit() is called 1942 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1943 // group should have the destroyed bit set before waiters are notified). 1944 ensure_join(this); 1945 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1946 1947 if (log_is_enabled(Debug, os, thread, timer)) { 1948 _timer_exit_phase2.stop(); 1949 _timer_exit_phase3.start(); 1950 } 1951 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1952 // held by this thread must be released. The spec does not distinguish 1953 // between JNI-acquired and regular Java monitors. We can only see 1954 // regular Java monitors here if monitor enter-exit matching is broken. 1955 // 1956 // Optionally release any monitors for regular JavaThread exits. This 1957 // is provided as a work around for any bugs in monitor enter-exit 1958 // matching. This can be expensive so it is not enabled by default. 1959 // 1960 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1961 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1962 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1963 // Sanity check even though JNI DetachCurrentThread() would have 1964 // returned JNI_ERR if there was a Java frame. JavaThread exit 1965 // should be done executing Java code by the time we get here. 1966 assert(!this->has_last_Java_frame(), 1967 "should not have a Java frame when detaching or exiting"); 1968 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1969 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1970 } 1971 1972 // These things needs to be done while we are still a Java Thread. Make sure that thread 1973 // is in a consistent state, in case GC happens 1974 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1975 1976 if (active_handles() != NULL) { 1977 JNIHandleBlock* block = active_handles(); 1978 set_active_handles(NULL); 1979 JNIHandleBlock::release_block(block); 1980 } 1981 1982 if (free_handle_block() != NULL) { 1983 JNIHandleBlock* block = free_handle_block(); 1984 set_free_handle_block(NULL); 1985 JNIHandleBlock::release_block(block); 1986 } 1987 1988 // These have to be removed while this is still a valid thread. 1989 remove_stack_guard_pages(); 1990 1991 if (UseTLAB) { 1992 tlab().make_parsable(true); // retire TLAB 1993 } 1994 1995 if (JvmtiEnv::environments_might_exist()) { 1996 JvmtiExport::cleanup_thread(this); 1997 } 1998 1999 // We must flush any deferred card marks and other various GC barrier 2000 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2001 // before removing a thread from the list of active threads. 2002 BarrierSet::barrier_set()->on_thread_detach(this); 2003 2004 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2005 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2006 os::current_thread_id()); 2007 2008 if (log_is_enabled(Debug, os, thread, timer)) { 2009 _timer_exit_phase3.stop(); 2010 _timer_exit_phase4.start(); 2011 } 2012 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2013 Threads::remove(this); 2014 2015 if (log_is_enabled(Debug, os, thread, timer)) { 2016 _timer_exit_phase4.stop(); 2017 ResourceMark rm(this); 2018 log_debug(os, thread, timer)("name='%s'" 2019 ", exit-phase1=" JLONG_FORMAT 2020 ", exit-phase2=" JLONG_FORMAT 2021 ", exit-phase3=" JLONG_FORMAT 2022 ", exit-phase4=" JLONG_FORMAT, 2023 get_thread_name(), 2024 _timer_exit_phase1.milliseconds(), 2025 _timer_exit_phase2.milliseconds(), 2026 _timer_exit_phase3.milliseconds(), 2027 _timer_exit_phase4.milliseconds()); 2028 } 2029 } 2030 2031 void JavaThread::cleanup_failed_attach_current_thread() { 2032 if (active_handles() != NULL) { 2033 JNIHandleBlock* block = active_handles(); 2034 set_active_handles(NULL); 2035 JNIHandleBlock::release_block(block); 2036 } 2037 2038 if (free_handle_block() != NULL) { 2039 JNIHandleBlock* block = free_handle_block(); 2040 set_free_handle_block(NULL); 2041 JNIHandleBlock::release_block(block); 2042 } 2043 2044 // These have to be removed while this is still a valid thread. 2045 remove_stack_guard_pages(); 2046 2047 if (UseTLAB) { 2048 tlab().make_parsable(true); // retire TLAB, if any 2049 } 2050 2051 BarrierSet::barrier_set()->on_thread_detach(this); 2052 2053 Threads::remove(this); 2054 this->smr_delete(); 2055 } 2056 2057 JavaThread* JavaThread::active() { 2058 Thread* thread = Thread::current(); 2059 if (thread->is_Java_thread()) { 2060 return (JavaThread*) thread; 2061 } else { 2062 assert(thread->is_VM_thread(), "this must be a vm thread"); 2063 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2064 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2065 assert(ret->is_Java_thread(), "must be a Java thread"); 2066 return ret; 2067 } 2068 } 2069 2070 bool JavaThread::is_lock_owned(address adr) const { 2071 if (Thread::is_lock_owned(adr)) return true; 2072 2073 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2074 if (chunk->contains(adr)) return true; 2075 } 2076 2077 return false; 2078 } 2079 2080 2081 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2082 chunk->set_next(monitor_chunks()); 2083 set_monitor_chunks(chunk); 2084 } 2085 2086 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2087 guarantee(monitor_chunks() != NULL, "must be non empty"); 2088 if (monitor_chunks() == chunk) { 2089 set_monitor_chunks(chunk->next()); 2090 } else { 2091 MonitorChunk* prev = monitor_chunks(); 2092 while (prev->next() != chunk) prev = prev->next(); 2093 prev->set_next(chunk->next()); 2094 } 2095 } 2096 2097 // JVM support. 2098 2099 // Note: this function shouldn't block if it's called in 2100 // _thread_in_native_trans state (such as from 2101 // check_special_condition_for_native_trans()). 2102 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2103 2104 if (has_last_Java_frame() && has_async_condition()) { 2105 // If we are at a polling page safepoint (not a poll return) 2106 // then we must defer async exception because live registers 2107 // will be clobbered by the exception path. Poll return is 2108 // ok because the call we a returning from already collides 2109 // with exception handling registers and so there is no issue. 2110 // (The exception handling path kills call result registers but 2111 // this is ok since the exception kills the result anyway). 2112 2113 if (is_at_poll_safepoint()) { 2114 // if the code we are returning to has deoptimized we must defer 2115 // the exception otherwise live registers get clobbered on the 2116 // exception path before deoptimization is able to retrieve them. 2117 // 2118 RegisterMap map(this, false); 2119 frame caller_fr = last_frame().sender(&map); 2120 assert(caller_fr.is_compiled_frame(), "what?"); 2121 if (caller_fr.is_deoptimized_frame()) { 2122 log_info(exceptions)("deferred async exception at compiled safepoint"); 2123 return; 2124 } 2125 } 2126 } 2127 2128 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2129 if (condition == _no_async_condition) { 2130 // Conditions have changed since has_special_runtime_exit_condition() 2131 // was called: 2132 // - if we were here only because of an external suspend request, 2133 // then that was taken care of above (or cancelled) so we are done 2134 // - if we were here because of another async request, then it has 2135 // been cleared between the has_special_runtime_exit_condition() 2136 // and now so again we are done 2137 return; 2138 } 2139 2140 // Check for pending async. exception 2141 if (_pending_async_exception != NULL) { 2142 // Only overwrite an already pending exception, if it is not a threadDeath. 2143 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2144 2145 // We cannot call Exceptions::_throw(...) here because we cannot block 2146 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2147 2148 LogTarget(Info, exceptions) lt; 2149 if (lt.is_enabled()) { 2150 ResourceMark rm; 2151 LogStream ls(lt); 2152 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2153 if (has_last_Java_frame()) { 2154 frame f = last_frame(); 2155 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2156 } 2157 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2158 } 2159 _pending_async_exception = NULL; 2160 clear_has_async_exception(); 2161 } 2162 } 2163 2164 if (check_unsafe_error && 2165 condition == _async_unsafe_access_error && !has_pending_exception()) { 2166 condition = _no_async_condition; // done 2167 switch (thread_state()) { 2168 case _thread_in_vm: { 2169 JavaThread* THREAD = this; 2170 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2171 } 2172 case _thread_in_native: { 2173 ThreadInVMfromNative tiv(this); 2174 JavaThread* THREAD = this; 2175 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2176 } 2177 case _thread_in_Java: { 2178 ThreadInVMfromJava tiv(this); 2179 JavaThread* THREAD = this; 2180 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2181 } 2182 default: 2183 ShouldNotReachHere(); 2184 } 2185 } 2186 2187 assert(condition == _no_async_condition || has_pending_exception() || 2188 (!check_unsafe_error && condition == _async_unsafe_access_error), 2189 "must have handled the async condition, if no exception"); 2190 } 2191 2192 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2193 // 2194 // Check for pending external suspend. Internal suspend requests do 2195 // not use handle_special_runtime_exit_condition(). 2196 // If JNIEnv proxies are allowed, don't self-suspend if the target 2197 // thread is not the current thread. In older versions of jdbx, jdbx 2198 // threads could call into the VM with another thread's JNIEnv so we 2199 // can be here operating on behalf of a suspended thread (4432884). 2200 bool do_self_suspend = is_external_suspend_with_lock(); 2201 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2202 // 2203 // Because thread is external suspended the safepoint code will count 2204 // thread as at a safepoint. This can be odd because we can be here 2205 // as _thread_in_Java which would normally transition to _thread_blocked 2206 // at a safepoint. We would like to mark the thread as _thread_blocked 2207 // before calling java_suspend_self like all other callers of it but 2208 // we must then observe proper safepoint protocol. (We can't leave 2209 // _thread_blocked with a safepoint in progress). However we can be 2210 // here as _thread_in_native_trans so we can't use a normal transition 2211 // constructor/destructor pair because they assert on that type of 2212 // transition. We could do something like: 2213 // 2214 // JavaThreadState state = thread_state(); 2215 // set_thread_state(_thread_in_vm); 2216 // { 2217 // ThreadBlockInVM tbivm(this); 2218 // java_suspend_self() 2219 // } 2220 // set_thread_state(_thread_in_vm_trans); 2221 // if (safepoint) block; 2222 // set_thread_state(state); 2223 // 2224 // but that is pretty messy. Instead we just go with the way the 2225 // code has worked before and note that this is the only path to 2226 // java_suspend_self that doesn't put the thread in _thread_blocked 2227 // mode. 2228 2229 frame_anchor()->make_walkable(this); 2230 java_suspend_self(); 2231 2232 // We might be here for reasons in addition to the self-suspend request 2233 // so check for other async requests. 2234 } 2235 2236 if (check_asyncs) { 2237 check_and_handle_async_exceptions(); 2238 } 2239 #if INCLUDE_TRACE 2240 if (is_trace_suspend()) { 2241 TRACE_SUSPEND_THREAD(this); 2242 } 2243 #endif 2244 } 2245 2246 void JavaThread::send_thread_stop(oop java_throwable) { 2247 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2248 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2249 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2250 2251 // Do not throw asynchronous exceptions against the compiler thread 2252 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2253 if (!can_call_java()) return; 2254 2255 { 2256 // Actually throw the Throwable against the target Thread - however 2257 // only if there is no thread death exception installed already. 2258 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2259 // If the topmost frame is a runtime stub, then we are calling into 2260 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2261 // must deoptimize the caller before continuing, as the compiled exception handler table 2262 // may not be valid 2263 if (has_last_Java_frame()) { 2264 frame f = last_frame(); 2265 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2266 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2267 RegisterMap reg_map(this, UseBiasedLocking); 2268 frame compiled_frame = f.sender(®_map); 2269 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2270 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2271 } 2272 } 2273 } 2274 2275 // Set async. pending exception in thread. 2276 set_pending_async_exception(java_throwable); 2277 2278 if (log_is_enabled(Info, exceptions)) { 2279 ResourceMark rm; 2280 log_info(exceptions)("Pending Async. exception installed of type: %s", 2281 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2282 } 2283 // for AbortVMOnException flag 2284 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2285 } 2286 } 2287 2288 2289 // Interrupt thread so it will wake up from a potential wait() 2290 Thread::interrupt(this); 2291 } 2292 2293 // External suspension mechanism. 2294 // 2295 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2296 // to any VM_locks and it is at a transition 2297 // Self-suspension will happen on the transition out of the vm. 2298 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2299 // 2300 // Guarantees on return: 2301 // + Target thread will not execute any new bytecode (that's why we need to 2302 // force a safepoint) 2303 // + Target thread will not enter any new monitors 2304 // 2305 void JavaThread::java_suspend() { 2306 ThreadsListHandle tlh; 2307 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2308 return; 2309 } 2310 2311 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2312 if (!is_external_suspend()) { 2313 // a racing resume has cancelled us; bail out now 2314 return; 2315 } 2316 2317 // suspend is done 2318 uint32_t debug_bits = 0; 2319 // Warning: is_ext_suspend_completed() may temporarily drop the 2320 // SR_lock to allow the thread to reach a stable thread state if 2321 // it is currently in a transient thread state. 2322 if (is_ext_suspend_completed(false /* !called_by_wait */, 2323 SuspendRetryDelay, &debug_bits)) { 2324 return; 2325 } 2326 } 2327 2328 VM_ThreadSuspend vm_suspend; 2329 VMThread::execute(&vm_suspend); 2330 } 2331 2332 // Part II of external suspension. 2333 // A JavaThread self suspends when it detects a pending external suspend 2334 // request. This is usually on transitions. It is also done in places 2335 // where continuing to the next transition would surprise the caller, 2336 // e.g., monitor entry. 2337 // 2338 // Returns the number of times that the thread self-suspended. 2339 // 2340 // Note: DO NOT call java_suspend_self() when you just want to block current 2341 // thread. java_suspend_self() is the second stage of cooperative 2342 // suspension for external suspend requests and should only be used 2343 // to complete an external suspend request. 2344 // 2345 int JavaThread::java_suspend_self() { 2346 int ret = 0; 2347 2348 // we are in the process of exiting so don't suspend 2349 if (is_exiting()) { 2350 clear_external_suspend(); 2351 return ret; 2352 } 2353 2354 assert(_anchor.walkable() || 2355 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2356 "must have walkable stack"); 2357 2358 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2359 2360 assert(!this->is_ext_suspended(), 2361 "a thread trying to self-suspend should not already be suspended"); 2362 2363 if (this->is_suspend_equivalent()) { 2364 // If we are self-suspending as a result of the lifting of a 2365 // suspend equivalent condition, then the suspend_equivalent 2366 // flag is not cleared until we set the ext_suspended flag so 2367 // that wait_for_ext_suspend_completion() returns consistent 2368 // results. 2369 this->clear_suspend_equivalent(); 2370 } 2371 2372 // A racing resume may have cancelled us before we grabbed SR_lock 2373 // above. Or another external suspend request could be waiting for us 2374 // by the time we return from SR_lock()->wait(). The thread 2375 // that requested the suspension may already be trying to walk our 2376 // stack and if we return now, we can change the stack out from under 2377 // it. This would be a "bad thing (TM)" and cause the stack walker 2378 // to crash. We stay self-suspended until there are no more pending 2379 // external suspend requests. 2380 while (is_external_suspend()) { 2381 ret++; 2382 this->set_ext_suspended(); 2383 2384 // _ext_suspended flag is cleared by java_resume() 2385 while (is_ext_suspended()) { 2386 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2387 } 2388 } 2389 2390 return ret; 2391 } 2392 2393 #ifdef ASSERT 2394 // Verify the JavaThread has not yet been published in the Threads::list, and 2395 // hence doesn't need protection from concurrent access at this stage. 2396 void JavaThread::verify_not_published() { 2397 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2398 // since an unpublished JavaThread doesn't participate in the 2399 // Thread-SMR protocol for keeping a ThreadsList alive. 2400 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2401 } 2402 #endif 2403 2404 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2405 // progress or when _suspend_flags is non-zero. 2406 // Current thread needs to self-suspend if there is a suspend request and/or 2407 // block if a safepoint is in progress. 2408 // Async exception ISN'T checked. 2409 // Note only the ThreadInVMfromNative transition can call this function 2410 // directly and when thread state is _thread_in_native_trans 2411 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2412 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2413 2414 JavaThread *curJT = JavaThread::current(); 2415 bool do_self_suspend = thread->is_external_suspend(); 2416 2417 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2418 2419 // If JNIEnv proxies are allowed, don't self-suspend if the target 2420 // thread is not the current thread. In older versions of jdbx, jdbx 2421 // threads could call into the VM with another thread's JNIEnv so we 2422 // can be here operating on behalf of a suspended thread (4432884). 2423 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2424 JavaThreadState state = thread->thread_state(); 2425 2426 // We mark this thread_blocked state as a suspend-equivalent so 2427 // that a caller to is_ext_suspend_completed() won't be confused. 2428 // The suspend-equivalent state is cleared by java_suspend_self(). 2429 thread->set_suspend_equivalent(); 2430 2431 // If the safepoint code sees the _thread_in_native_trans state, it will 2432 // wait until the thread changes to other thread state. There is no 2433 // guarantee on how soon we can obtain the SR_lock and complete the 2434 // self-suspend request. It would be a bad idea to let safepoint wait for 2435 // too long. Temporarily change the state to _thread_blocked to 2436 // let the VM thread know that this thread is ready for GC. The problem 2437 // of changing thread state is that safepoint could happen just after 2438 // java_suspend_self() returns after being resumed, and VM thread will 2439 // see the _thread_blocked state. We must check for safepoint 2440 // after restoring the state and make sure we won't leave while a safepoint 2441 // is in progress. 2442 thread->set_thread_state(_thread_blocked); 2443 thread->java_suspend_self(); 2444 thread->set_thread_state(state); 2445 2446 InterfaceSupport::serialize_thread_state_with_handler(thread); 2447 } 2448 2449 SafepointMechanism::block_if_requested(curJT); 2450 2451 if (thread->is_deopt_suspend()) { 2452 thread->clear_deopt_suspend(); 2453 RegisterMap map(thread, false); 2454 frame f = thread->last_frame(); 2455 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2456 f = f.sender(&map); 2457 } 2458 if (f.id() == thread->must_deopt_id()) { 2459 thread->clear_must_deopt_id(); 2460 f.deoptimize(thread); 2461 } else { 2462 fatal("missed deoptimization!"); 2463 } 2464 } 2465 #if INCLUDE_TRACE 2466 if (thread->is_trace_suspend()) { 2467 TRACE_SUSPEND_THREAD(thread); 2468 } 2469 #endif 2470 } 2471 2472 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2473 // progress or when _suspend_flags is non-zero. 2474 // Current thread needs to self-suspend if there is a suspend request and/or 2475 // block if a safepoint is in progress. 2476 // Also check for pending async exception (not including unsafe access error). 2477 // Note only the native==>VM/Java barriers can call this function and when 2478 // thread state is _thread_in_native_trans. 2479 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2480 check_safepoint_and_suspend_for_native_trans(thread); 2481 2482 if (thread->has_async_exception()) { 2483 // We are in _thread_in_native_trans state, don't handle unsafe 2484 // access error since that may block. 2485 thread->check_and_handle_async_exceptions(false); 2486 } 2487 } 2488 2489 // This is a variant of the normal 2490 // check_special_condition_for_native_trans with slightly different 2491 // semantics for use by critical native wrappers. It does all the 2492 // normal checks but also performs the transition back into 2493 // thread_in_Java state. This is required so that critical natives 2494 // can potentially block and perform a GC if they are the last thread 2495 // exiting the GCLocker. 2496 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2497 check_special_condition_for_native_trans(thread); 2498 2499 // Finish the transition 2500 thread->set_thread_state(_thread_in_Java); 2501 2502 if (thread->do_critical_native_unlock()) { 2503 ThreadInVMfromJavaNoAsyncException tiv(thread); 2504 GCLocker::unlock_critical(thread); 2505 thread->clear_critical_native_unlock(); 2506 } 2507 } 2508 2509 // We need to guarantee the Threads_lock here, since resumes are not 2510 // allowed during safepoint synchronization 2511 // Can only resume from an external suspension 2512 void JavaThread::java_resume() { 2513 assert_locked_or_safepoint(Threads_lock); 2514 2515 // Sanity check: thread is gone, has started exiting or the thread 2516 // was not externally suspended. 2517 ThreadsListHandle tlh; 2518 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2519 return; 2520 } 2521 2522 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2523 2524 clear_external_suspend(); 2525 2526 if (is_ext_suspended()) { 2527 clear_ext_suspended(); 2528 SR_lock()->notify_all(); 2529 } 2530 } 2531 2532 size_t JavaThread::_stack_red_zone_size = 0; 2533 size_t JavaThread::_stack_yellow_zone_size = 0; 2534 size_t JavaThread::_stack_reserved_zone_size = 0; 2535 size_t JavaThread::_stack_shadow_zone_size = 0; 2536 2537 void JavaThread::create_stack_guard_pages() { 2538 if (!os::uses_stack_guard_pages() || 2539 _stack_guard_state != stack_guard_unused || 2540 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2541 log_info(os, thread)("Stack guard page creation for thread " 2542 UINTX_FORMAT " disabled", os::current_thread_id()); 2543 return; 2544 } 2545 address low_addr = stack_end(); 2546 size_t len = stack_guard_zone_size(); 2547 2548 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2549 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2550 2551 int must_commit = os::must_commit_stack_guard_pages(); 2552 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2553 2554 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2555 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2556 return; 2557 } 2558 2559 if (os::guard_memory((char *) low_addr, len)) { 2560 _stack_guard_state = stack_guard_enabled; 2561 } else { 2562 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2563 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2564 if (os::uncommit_memory((char *) low_addr, len)) { 2565 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2566 } 2567 return; 2568 } 2569 2570 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2571 PTR_FORMAT "-" PTR_FORMAT ".", 2572 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2573 } 2574 2575 void JavaThread::remove_stack_guard_pages() { 2576 assert(Thread::current() == this, "from different thread"); 2577 if (_stack_guard_state == stack_guard_unused) return; 2578 address low_addr = stack_end(); 2579 size_t len = stack_guard_zone_size(); 2580 2581 if (os::must_commit_stack_guard_pages()) { 2582 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2583 _stack_guard_state = stack_guard_unused; 2584 } else { 2585 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2586 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2587 return; 2588 } 2589 } else { 2590 if (_stack_guard_state == stack_guard_unused) return; 2591 if (os::unguard_memory((char *) low_addr, len)) { 2592 _stack_guard_state = stack_guard_unused; 2593 } else { 2594 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2595 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2596 return; 2597 } 2598 } 2599 2600 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2601 PTR_FORMAT "-" PTR_FORMAT ".", 2602 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2603 } 2604 2605 void JavaThread::enable_stack_reserved_zone() { 2606 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2607 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2608 2609 // The base notation is from the stack's point of view, growing downward. 2610 // We need to adjust it to work correctly with guard_memory() 2611 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2612 2613 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2614 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2615 2616 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2617 _stack_guard_state = stack_guard_enabled; 2618 } else { 2619 warning("Attempt to guard stack reserved zone failed."); 2620 } 2621 enable_register_stack_guard(); 2622 } 2623 2624 void JavaThread::disable_stack_reserved_zone() { 2625 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2626 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2627 2628 // Simply return if called for a thread that does not use guard pages. 2629 if (_stack_guard_state == stack_guard_unused) return; 2630 2631 // The base notation is from the stack's point of view, growing downward. 2632 // We need to adjust it to work correctly with guard_memory() 2633 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2634 2635 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2636 _stack_guard_state = stack_guard_reserved_disabled; 2637 } else { 2638 warning("Attempt to unguard stack reserved zone failed."); 2639 } 2640 disable_register_stack_guard(); 2641 } 2642 2643 void JavaThread::enable_stack_yellow_reserved_zone() { 2644 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2645 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2646 2647 // The base notation is from the stacks point of view, growing downward. 2648 // We need to adjust it to work correctly with guard_memory() 2649 address base = stack_red_zone_base(); 2650 2651 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2652 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2653 2654 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2655 _stack_guard_state = stack_guard_enabled; 2656 } else { 2657 warning("Attempt to guard stack yellow zone failed."); 2658 } 2659 enable_register_stack_guard(); 2660 } 2661 2662 void JavaThread::disable_stack_yellow_reserved_zone() { 2663 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2664 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2665 2666 // Simply return if called for a thread that does not use guard pages. 2667 if (_stack_guard_state == stack_guard_unused) return; 2668 2669 // The base notation is from the stacks point of view, growing downward. 2670 // We need to adjust it to work correctly with guard_memory() 2671 address base = stack_red_zone_base(); 2672 2673 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2674 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2675 } else { 2676 warning("Attempt to unguard stack yellow zone failed."); 2677 } 2678 disable_register_stack_guard(); 2679 } 2680 2681 void JavaThread::enable_stack_red_zone() { 2682 // The base notation is from the stacks point of view, growing downward. 2683 // We need to adjust it to work correctly with guard_memory() 2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2685 address base = stack_red_zone_base() - stack_red_zone_size(); 2686 2687 guarantee(base < stack_base(), "Error calculating stack red zone"); 2688 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2689 2690 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2691 warning("Attempt to guard stack red zone failed."); 2692 } 2693 } 2694 2695 void JavaThread::disable_stack_red_zone() { 2696 // The base notation is from the stacks point of view, growing downward. 2697 // We need to adjust it to work correctly with guard_memory() 2698 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2699 address base = stack_red_zone_base() - stack_red_zone_size(); 2700 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2701 warning("Attempt to unguard stack red zone failed."); 2702 } 2703 } 2704 2705 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2706 // ignore is there is no stack 2707 if (!has_last_Java_frame()) return; 2708 // traverse the stack frames. Starts from top frame. 2709 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2710 frame* fr = fst.current(); 2711 f(fr, fst.register_map()); 2712 } 2713 } 2714 2715 2716 #ifndef PRODUCT 2717 // Deoptimization 2718 // Function for testing deoptimization 2719 void JavaThread::deoptimize() { 2720 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2721 StackFrameStream fst(this, UseBiasedLocking); 2722 bool deopt = false; // Dump stack only if a deopt actually happens. 2723 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2724 // Iterate over all frames in the thread and deoptimize 2725 for (; !fst.is_done(); fst.next()) { 2726 if (fst.current()->can_be_deoptimized()) { 2727 2728 if (only_at) { 2729 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2730 // consists of comma or carriage return separated numbers so 2731 // search for the current bci in that string. 2732 address pc = fst.current()->pc(); 2733 nmethod* nm = (nmethod*) fst.current()->cb(); 2734 ScopeDesc* sd = nm->scope_desc_at(pc); 2735 char buffer[8]; 2736 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2737 size_t len = strlen(buffer); 2738 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2739 while (found != NULL) { 2740 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2741 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2742 // Check that the bci found is bracketed by terminators. 2743 break; 2744 } 2745 found = strstr(found + 1, buffer); 2746 } 2747 if (!found) { 2748 continue; 2749 } 2750 } 2751 2752 if (DebugDeoptimization && !deopt) { 2753 deopt = true; // One-time only print before deopt 2754 tty->print_cr("[BEFORE Deoptimization]"); 2755 trace_frames(); 2756 trace_stack(); 2757 } 2758 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2759 } 2760 } 2761 2762 if (DebugDeoptimization && deopt) { 2763 tty->print_cr("[AFTER Deoptimization]"); 2764 trace_frames(); 2765 } 2766 } 2767 2768 2769 // Make zombies 2770 void JavaThread::make_zombies() { 2771 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2772 if (fst.current()->can_be_deoptimized()) { 2773 // it is a Java nmethod 2774 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2775 nm->make_not_entrant(); 2776 } 2777 } 2778 } 2779 #endif // PRODUCT 2780 2781 2782 void JavaThread::deoptimized_wrt_marked_nmethods() { 2783 if (!has_last_Java_frame()) return; 2784 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2785 StackFrameStream fst(this, UseBiasedLocking); 2786 for (; !fst.is_done(); fst.next()) { 2787 if (fst.current()->should_be_deoptimized()) { 2788 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2789 } 2790 } 2791 } 2792 2793 2794 // If the caller is a NamedThread, then remember, in the current scope, 2795 // the given JavaThread in its _processed_thread field. 2796 class RememberProcessedThread: public StackObj { 2797 NamedThread* _cur_thr; 2798 public: 2799 RememberProcessedThread(JavaThread* jthr) { 2800 Thread* thread = Thread::current(); 2801 if (thread->is_Named_thread()) { 2802 _cur_thr = (NamedThread *)thread; 2803 _cur_thr->set_processed_thread(jthr); 2804 } else { 2805 _cur_thr = NULL; 2806 } 2807 } 2808 2809 ~RememberProcessedThread() { 2810 if (_cur_thr) { 2811 _cur_thr->set_processed_thread(NULL); 2812 } 2813 } 2814 }; 2815 2816 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2817 // Verify that the deferred card marks have been flushed. 2818 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2819 2820 // Traverse the GCHandles 2821 Thread::oops_do(f, cf); 2822 2823 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2824 2825 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2826 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2827 2828 if (has_last_Java_frame()) { 2829 // Record JavaThread to GC thread 2830 RememberProcessedThread rpt(this); 2831 2832 // Traverse the privileged stack 2833 if (_privileged_stack_top != NULL) { 2834 _privileged_stack_top->oops_do(f); 2835 } 2836 2837 // traverse the registered growable array 2838 if (_array_for_gc != NULL) { 2839 for (int index = 0; index < _array_for_gc->length(); index++) { 2840 f->do_oop(_array_for_gc->adr_at(index)); 2841 } 2842 } 2843 2844 // Traverse the monitor chunks 2845 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2846 chunk->oops_do(f); 2847 } 2848 2849 // Traverse the execution stack 2850 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2851 fst.current()->oops_do(f, cf, fst.register_map()); 2852 } 2853 } 2854 2855 // callee_target is never live across a gc point so NULL it here should 2856 // it still contain a methdOop. 2857 2858 set_callee_target(NULL); 2859 2860 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2861 // If we have deferred set_locals there might be oops waiting to be 2862 // written 2863 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2864 if (list != NULL) { 2865 for (int i = 0; i < list->length(); i++) { 2866 list->at(i)->oops_do(f); 2867 } 2868 } 2869 2870 // Traverse instance variables at the end since the GC may be moving things 2871 // around using this function 2872 f->do_oop((oop*) &_threadObj); 2873 f->do_oop((oop*) &_vm_result); 2874 f->do_oop((oop*) &_exception_oop); 2875 f->do_oop((oop*) &_pending_async_exception); 2876 2877 if (jvmti_thread_state() != NULL) { 2878 jvmti_thread_state()->oops_do(f); 2879 } 2880 } 2881 2882 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2883 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2884 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2885 2886 if (has_last_Java_frame()) { 2887 // Traverse the execution stack 2888 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2889 fst.current()->nmethods_do(cf); 2890 } 2891 } 2892 } 2893 2894 void JavaThread::metadata_do(void f(Metadata*)) { 2895 if (has_last_Java_frame()) { 2896 // Traverse the execution stack to call f() on the methods in the stack 2897 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2898 fst.current()->metadata_do(f); 2899 } 2900 } else if (is_Compiler_thread()) { 2901 // need to walk ciMetadata in current compile tasks to keep alive. 2902 CompilerThread* ct = (CompilerThread*)this; 2903 if (ct->env() != NULL) { 2904 ct->env()->metadata_do(f); 2905 } 2906 CompileTask* task = ct->task(); 2907 if (task != NULL) { 2908 task->metadata_do(f); 2909 } 2910 } 2911 } 2912 2913 // Printing 2914 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2915 switch (_thread_state) { 2916 case _thread_uninitialized: return "_thread_uninitialized"; 2917 case _thread_new: return "_thread_new"; 2918 case _thread_new_trans: return "_thread_new_trans"; 2919 case _thread_in_native: return "_thread_in_native"; 2920 case _thread_in_native_trans: return "_thread_in_native_trans"; 2921 case _thread_in_vm: return "_thread_in_vm"; 2922 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2923 case _thread_in_Java: return "_thread_in_Java"; 2924 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2925 case _thread_blocked: return "_thread_blocked"; 2926 case _thread_blocked_trans: return "_thread_blocked_trans"; 2927 default: return "unknown thread state"; 2928 } 2929 } 2930 2931 #ifndef PRODUCT 2932 void JavaThread::print_thread_state_on(outputStream *st) const { 2933 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2934 }; 2935 void JavaThread::print_thread_state() const { 2936 print_thread_state_on(tty); 2937 } 2938 #endif // PRODUCT 2939 2940 // Called by Threads::print() for VM_PrintThreads operation 2941 void JavaThread::print_on(outputStream *st) const { 2942 st->print_raw("\""); 2943 st->print_raw(get_thread_name()); 2944 st->print_raw("\" "); 2945 oop thread_oop = threadObj(); 2946 if (thread_oop != NULL) { 2947 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2948 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2949 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2950 } 2951 Thread::print_on(st); 2952 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2953 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2954 if (thread_oop != NULL) { 2955 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2956 } 2957 #ifndef PRODUCT 2958 print_thread_state_on(st); 2959 _safepoint_state->print_on(st); 2960 #endif // PRODUCT 2961 if (is_Compiler_thread()) { 2962 CompileTask *task = ((CompilerThread*)this)->task(); 2963 if (task != NULL) { 2964 st->print(" Compiling: "); 2965 task->print(st, NULL, true, false); 2966 } else { 2967 st->print(" No compile task"); 2968 } 2969 st->cr(); 2970 } 2971 } 2972 2973 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2974 st->print("%s", get_thread_name_string(buf, buflen)); 2975 } 2976 2977 // Called by fatal error handler. The difference between this and 2978 // JavaThread::print() is that we can't grab lock or allocate memory. 2979 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2980 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2981 oop thread_obj = threadObj(); 2982 if (thread_obj != NULL) { 2983 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2984 } 2985 st->print(" ["); 2986 st->print("%s", _get_thread_state_name(_thread_state)); 2987 if (osthread()) { 2988 st->print(", id=%d", osthread()->thread_id()); 2989 } 2990 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2991 p2i(stack_end()), p2i(stack_base())); 2992 st->print("]"); 2993 2994 if (_threads_hazard_ptr != NULL) { 2995 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 2996 } 2997 if (_nested_threads_hazard_ptr != NULL) { 2998 print_nested_threads_hazard_ptrs_on(st); 2999 } 3000 return; 3001 } 3002 3003 // Verification 3004 3005 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3006 3007 void JavaThread::verify() { 3008 // Verify oops in the thread. 3009 oops_do(&VerifyOopClosure::verify_oop, NULL); 3010 3011 // Verify the stack frames. 3012 frames_do(frame_verify); 3013 } 3014 3015 // CR 6300358 (sub-CR 2137150) 3016 // Most callers of this method assume that it can't return NULL but a 3017 // thread may not have a name whilst it is in the process of attaching to 3018 // the VM - see CR 6412693, and there are places where a JavaThread can be 3019 // seen prior to having it's threadObj set (eg JNI attaching threads and 3020 // if vm exit occurs during initialization). These cases can all be accounted 3021 // for such that this method never returns NULL. 3022 const char* JavaThread::get_thread_name() const { 3023 #ifdef ASSERT 3024 // early safepoints can hit while current thread does not yet have TLS 3025 if (!SafepointSynchronize::is_at_safepoint()) { 3026 Thread *cur = Thread::current(); 3027 if (!(cur->is_Java_thread() && cur == this)) { 3028 // Current JavaThreads are allowed to get their own name without 3029 // the Threads_lock. 3030 assert_locked_or_safepoint(Threads_lock); 3031 } 3032 } 3033 #endif // ASSERT 3034 return get_thread_name_string(); 3035 } 3036 3037 // Returns a non-NULL representation of this thread's name, or a suitable 3038 // descriptive string if there is no set name 3039 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3040 const char* name_str; 3041 oop thread_obj = threadObj(); 3042 if (thread_obj != NULL) { 3043 oop name = java_lang_Thread::name(thread_obj); 3044 if (name != NULL) { 3045 if (buf == NULL) { 3046 name_str = java_lang_String::as_utf8_string(name); 3047 } else { 3048 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3049 } 3050 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3051 name_str = "<no-name - thread is attaching>"; 3052 } else { 3053 name_str = Thread::name(); 3054 } 3055 } else { 3056 name_str = Thread::name(); 3057 } 3058 assert(name_str != NULL, "unexpected NULL thread name"); 3059 return name_str; 3060 } 3061 3062 3063 const char* JavaThread::get_threadgroup_name() const { 3064 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3065 oop thread_obj = threadObj(); 3066 if (thread_obj != NULL) { 3067 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3068 if (thread_group != NULL) { 3069 // ThreadGroup.name can be null 3070 return java_lang_ThreadGroup::name(thread_group); 3071 } 3072 } 3073 return NULL; 3074 } 3075 3076 const char* JavaThread::get_parent_name() const { 3077 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3078 oop thread_obj = threadObj(); 3079 if (thread_obj != NULL) { 3080 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3081 if (thread_group != NULL) { 3082 oop parent = java_lang_ThreadGroup::parent(thread_group); 3083 if (parent != NULL) { 3084 // ThreadGroup.name can be null 3085 return java_lang_ThreadGroup::name(parent); 3086 } 3087 } 3088 } 3089 return NULL; 3090 } 3091 3092 ThreadPriority JavaThread::java_priority() const { 3093 oop thr_oop = threadObj(); 3094 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3095 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3096 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3097 return priority; 3098 } 3099 3100 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3101 3102 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3103 // Link Java Thread object <-> C++ Thread 3104 3105 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3106 // and put it into a new Handle. The Handle "thread_oop" can then 3107 // be used to pass the C++ thread object to other methods. 3108 3109 // Set the Java level thread object (jthread) field of the 3110 // new thread (a JavaThread *) to C++ thread object using the 3111 // "thread_oop" handle. 3112 3113 // Set the thread field (a JavaThread *) of the 3114 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3115 3116 Handle thread_oop(Thread::current(), 3117 JNIHandles::resolve_non_null(jni_thread)); 3118 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3119 "must be initialized"); 3120 set_threadObj(thread_oop()); 3121 java_lang_Thread::set_thread(thread_oop(), this); 3122 3123 if (prio == NoPriority) { 3124 prio = java_lang_Thread::priority(thread_oop()); 3125 assert(prio != NoPriority, "A valid priority should be present"); 3126 } 3127 3128 // Push the Java priority down to the native thread; needs Threads_lock 3129 Thread::set_priority(this, prio); 3130 3131 // Add the new thread to the Threads list and set it in motion. 3132 // We must have threads lock in order to call Threads::add. 3133 // It is crucial that we do not block before the thread is 3134 // added to the Threads list for if a GC happens, then the java_thread oop 3135 // will not be visited by GC. 3136 Threads::add(this); 3137 } 3138 3139 oop JavaThread::current_park_blocker() { 3140 // Support for JSR-166 locks 3141 oop thread_oop = threadObj(); 3142 if (thread_oop != NULL && 3143 JDK_Version::current().supports_thread_park_blocker()) { 3144 return java_lang_Thread::park_blocker(thread_oop); 3145 } 3146 return NULL; 3147 } 3148 3149 3150 void JavaThread::print_stack_on(outputStream* st) { 3151 if (!has_last_Java_frame()) return; 3152 ResourceMark rm; 3153 HandleMark hm; 3154 3155 RegisterMap reg_map(this); 3156 vframe* start_vf = last_java_vframe(®_map); 3157 int count = 0; 3158 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3159 if (f->is_java_frame()) { 3160 javaVFrame* jvf = javaVFrame::cast(f); 3161 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3162 3163 // Print out lock information 3164 if (JavaMonitorsInStackTrace) { 3165 jvf->print_lock_info_on(st, count); 3166 } 3167 } else { 3168 // Ignore non-Java frames 3169 } 3170 3171 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3172 count++; 3173 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3174 } 3175 } 3176 3177 3178 // JVMTI PopFrame support 3179 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3180 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3181 if (in_bytes(size_in_bytes) != 0) { 3182 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3183 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3184 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3185 } 3186 } 3187 3188 void* JavaThread::popframe_preserved_args() { 3189 return _popframe_preserved_args; 3190 } 3191 3192 ByteSize JavaThread::popframe_preserved_args_size() { 3193 return in_ByteSize(_popframe_preserved_args_size); 3194 } 3195 3196 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3197 int sz = in_bytes(popframe_preserved_args_size()); 3198 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3199 return in_WordSize(sz / wordSize); 3200 } 3201 3202 void JavaThread::popframe_free_preserved_args() { 3203 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3204 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3205 _popframe_preserved_args = NULL; 3206 _popframe_preserved_args_size = 0; 3207 } 3208 3209 #ifndef PRODUCT 3210 3211 void JavaThread::trace_frames() { 3212 tty->print_cr("[Describe stack]"); 3213 int frame_no = 1; 3214 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3215 tty->print(" %d. ", frame_no++); 3216 fst.current()->print_value_on(tty, this); 3217 tty->cr(); 3218 } 3219 } 3220 3221 class PrintAndVerifyOopClosure: public OopClosure { 3222 protected: 3223 template <class T> inline void do_oop_work(T* p) { 3224 oop obj = RawAccess<>::oop_load(p); 3225 if (obj == NULL) return; 3226 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3227 if (oopDesc::is_oop_or_null(obj)) { 3228 if (obj->is_objArray()) { 3229 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3230 } else { 3231 obj->print(); 3232 } 3233 } else { 3234 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3235 } 3236 tty->cr(); 3237 } 3238 public: 3239 virtual void do_oop(oop* p) { do_oop_work(p); } 3240 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3241 }; 3242 3243 3244 static void oops_print(frame* f, const RegisterMap *map) { 3245 PrintAndVerifyOopClosure print; 3246 f->print_value(); 3247 f->oops_do(&print, NULL, (RegisterMap*)map); 3248 } 3249 3250 // Print our all the locations that contain oops and whether they are 3251 // valid or not. This useful when trying to find the oldest frame 3252 // where an oop has gone bad since the frame walk is from youngest to 3253 // oldest. 3254 void JavaThread::trace_oops() { 3255 tty->print_cr("[Trace oops]"); 3256 frames_do(oops_print); 3257 } 3258 3259 3260 #ifdef ASSERT 3261 // Print or validate the layout of stack frames 3262 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3263 ResourceMark rm; 3264 PRESERVE_EXCEPTION_MARK; 3265 FrameValues values; 3266 int frame_no = 0; 3267 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3268 fst.current()->describe(values, ++frame_no); 3269 if (depth == frame_no) break; 3270 } 3271 if (validate_only) { 3272 values.validate(); 3273 } else { 3274 tty->print_cr("[Describe stack layout]"); 3275 values.print(this); 3276 } 3277 } 3278 #endif 3279 3280 void JavaThread::trace_stack_from(vframe* start_vf) { 3281 ResourceMark rm; 3282 int vframe_no = 1; 3283 for (vframe* f = start_vf; f; f = f->sender()) { 3284 if (f->is_java_frame()) { 3285 javaVFrame::cast(f)->print_activation(vframe_no++); 3286 } else { 3287 f->print(); 3288 } 3289 if (vframe_no > StackPrintLimit) { 3290 tty->print_cr("...<more frames>..."); 3291 return; 3292 } 3293 } 3294 } 3295 3296 3297 void JavaThread::trace_stack() { 3298 if (!has_last_Java_frame()) return; 3299 ResourceMark rm; 3300 HandleMark hm; 3301 RegisterMap reg_map(this); 3302 trace_stack_from(last_java_vframe(®_map)); 3303 } 3304 3305 3306 #endif // PRODUCT 3307 3308 3309 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3310 assert(reg_map != NULL, "a map must be given"); 3311 frame f = last_frame(); 3312 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3313 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3314 } 3315 return NULL; 3316 } 3317 3318 3319 Klass* JavaThread::security_get_caller_class(int depth) { 3320 vframeStream vfst(this); 3321 vfst.security_get_caller_frame(depth); 3322 if (!vfst.at_end()) { 3323 return vfst.method()->method_holder(); 3324 } 3325 return NULL; 3326 } 3327 3328 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3329 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3330 CompileBroker::compiler_thread_loop(); 3331 } 3332 3333 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3334 NMethodSweeper::sweeper_loop(); 3335 } 3336 3337 // Create a CompilerThread 3338 CompilerThread::CompilerThread(CompileQueue* queue, 3339 CompilerCounters* counters) 3340 : JavaThread(&compiler_thread_entry) { 3341 _env = NULL; 3342 _log = NULL; 3343 _task = NULL; 3344 _queue = queue; 3345 _counters = counters; 3346 _buffer_blob = NULL; 3347 _compiler = NULL; 3348 3349 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3350 resource_area()->bias_to(mtCompiler); 3351 3352 #ifndef PRODUCT 3353 _ideal_graph_printer = NULL; 3354 #endif 3355 } 3356 3357 bool CompilerThread::can_call_java() const { 3358 return _compiler != NULL && _compiler->is_jvmci(); 3359 } 3360 3361 // Create sweeper thread 3362 CodeCacheSweeperThread::CodeCacheSweeperThread() 3363 : JavaThread(&sweeper_thread_entry) { 3364 _scanned_compiled_method = NULL; 3365 } 3366 3367 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3368 JavaThread::oops_do(f, cf); 3369 if (_scanned_compiled_method != NULL && cf != NULL) { 3370 // Safepoints can occur when the sweeper is scanning an nmethod so 3371 // process it here to make sure it isn't unloaded in the middle of 3372 // a scan. 3373 cf->do_code_blob(_scanned_compiled_method); 3374 } 3375 } 3376 3377 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3378 JavaThread::nmethods_do(cf); 3379 if (_scanned_compiled_method != NULL && cf != NULL) { 3380 // Safepoints can occur when the sweeper is scanning an nmethod so 3381 // process it here to make sure it isn't unloaded in the middle of 3382 // a scan. 3383 cf->do_code_blob(_scanned_compiled_method); 3384 } 3385 } 3386 3387 3388 // ======= Threads ======== 3389 3390 // The Threads class links together all active threads, and provides 3391 // operations over all threads. It is protected by the Threads_lock, 3392 // which is also used in other global contexts like safepointing. 3393 // ThreadsListHandles are used to safely perform operations on one 3394 // or more threads without the risk of the thread exiting during the 3395 // operation. 3396 // 3397 // Note: The Threads_lock is currently more widely used than we 3398 // would like. We are actively migrating Threads_lock uses to other 3399 // mechanisms in order to reduce Threads_lock contention. 3400 3401 JavaThread* Threads::_thread_list = NULL; 3402 int Threads::_number_of_threads = 0; 3403 int Threads::_number_of_non_daemon_threads = 0; 3404 int Threads::_return_code = 0; 3405 int Threads::_thread_claim_parity = 0; 3406 size_t JavaThread::_stack_size_at_create = 0; 3407 3408 #ifdef ASSERT 3409 bool Threads::_vm_complete = false; 3410 #endif 3411 3412 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3413 Prefetch::read((void*)addr, prefetch_interval); 3414 return *addr; 3415 } 3416 3417 // Possibly the ugliest for loop the world has seen. C++ does not allow 3418 // multiple types in the declaration section of the for loop. In this case 3419 // we are only dealing with pointers and hence can cast them. It looks ugly 3420 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3421 #define DO_JAVA_THREADS(LIST, X) \ 3422 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3423 *MACRO_list = (JavaThread*)(LIST), \ 3424 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3425 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3426 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3427 MACRO_current_p != MACRO_end; \ 3428 MACRO_current_p++, \ 3429 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3430 3431 // All JavaThreads 3432 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3433 3434 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3435 void Threads::threads_do(ThreadClosure* tc) { 3436 assert_locked_or_safepoint(Threads_lock); 3437 // ALL_JAVA_THREADS iterates through all JavaThreads 3438 ALL_JAVA_THREADS(p) { 3439 tc->do_thread(p); 3440 } 3441 // Someday we could have a table or list of all non-JavaThreads. 3442 // For now, just manually iterate through them. 3443 tc->do_thread(VMThread::vm_thread()); 3444 Universe::heap()->gc_threads_do(tc); 3445 WatcherThread *wt = WatcherThread::watcher_thread(); 3446 // Strictly speaking, the following NULL check isn't sufficient to make sure 3447 // the data for WatcherThread is still valid upon being examined. However, 3448 // considering that WatchThread terminates when the VM is on the way to 3449 // exit at safepoint, the chance of the above is extremely small. The right 3450 // way to prevent termination of WatcherThread would be to acquire 3451 // Terminator_lock, but we can't do that without violating the lock rank 3452 // checking in some cases. 3453 if (wt != NULL) { 3454 tc->do_thread(wt); 3455 } 3456 3457 // If CompilerThreads ever become non-JavaThreads, add them here 3458 } 3459 3460 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3461 int cp = Threads::thread_claim_parity(); 3462 ALL_JAVA_THREADS(p) { 3463 if (p->claim_oops_do(is_par, cp)) { 3464 tc->do_thread(p); 3465 } 3466 } 3467 VMThread* vmt = VMThread::vm_thread(); 3468 if (vmt->claim_oops_do(is_par, cp)) { 3469 tc->do_thread(vmt); 3470 } 3471 } 3472 3473 // The system initialization in the library has three phases. 3474 // 3475 // Phase 1: java.lang.System class initialization 3476 // java.lang.System is a primordial class loaded and initialized 3477 // by the VM early during startup. java.lang.System.<clinit> 3478 // only does registerNatives and keeps the rest of the class 3479 // initialization work later until thread initialization completes. 3480 // 3481 // System.initPhase1 initializes the system properties, the static 3482 // fields in, out, and err. Set up java signal handlers, OS-specific 3483 // system settings, and thread group of the main thread. 3484 static void call_initPhase1(TRAPS) { 3485 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3486 JavaValue result(T_VOID); 3487 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3488 vmSymbols::void_method_signature(), CHECK); 3489 } 3490 3491 // Phase 2. Module system initialization 3492 // This will initialize the module system. Only java.base classes 3493 // can be loaded until phase 2 completes. 3494 // 3495 // Call System.initPhase2 after the compiler initialization and jsr292 3496 // classes get initialized because module initialization runs a lot of java 3497 // code, that for performance reasons, should be compiled. Also, this will 3498 // enable the startup code to use lambda and other language features in this 3499 // phase and onward. 3500 // 3501 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3502 static void call_initPhase2(TRAPS) { 3503 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3504 3505 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3506 3507 JavaValue result(T_INT); 3508 JavaCallArguments args; 3509 args.push_int(DisplayVMOutputToStderr); 3510 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3511 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3512 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3513 if (result.get_jint() != JNI_OK) { 3514 vm_exit_during_initialization(); // no message or exception 3515 } 3516 3517 universe_post_module_init(); 3518 } 3519 3520 // Phase 3. final setup - set security manager, system class loader and TCCL 3521 // 3522 // This will instantiate and set the security manager, set the system class 3523 // loader as well as the thread context class loader. The security manager 3524 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3525 // other modules or the application's classpath. 3526 static void call_initPhase3(TRAPS) { 3527 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3528 JavaValue result(T_VOID); 3529 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3530 vmSymbols::void_method_signature(), CHECK); 3531 } 3532 3533 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3534 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3535 3536 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3537 create_vm_init_libraries(); 3538 } 3539 3540 initialize_class(vmSymbols::java_lang_String(), CHECK); 3541 3542 // Inject CompactStrings value after the static initializers for String ran. 3543 java_lang_String::set_compact_strings(CompactStrings); 3544 3545 // Initialize java_lang.System (needed before creating the thread) 3546 initialize_class(vmSymbols::java_lang_System(), CHECK); 3547 // The VM creates & returns objects of this class. Make sure it's initialized. 3548 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3549 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3550 Handle thread_group = create_initial_thread_group(CHECK); 3551 Universe::set_main_thread_group(thread_group()); 3552 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3553 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3554 main_thread->set_threadObj(thread_object); 3555 // Set thread status to running since main thread has 3556 // been started and running. 3557 java_lang_Thread::set_thread_status(thread_object, 3558 java_lang_Thread::RUNNABLE); 3559 3560 // The VM creates objects of this class. 3561 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3562 3563 // The VM preresolves methods to these classes. Make sure that they get initialized 3564 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3565 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3566 3567 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3568 call_initPhase1(CHECK); 3569 3570 // get the Java runtime name after java.lang.System is initialized 3571 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3572 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3573 3574 // an instance of OutOfMemory exception has been allocated earlier 3575 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3576 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3577 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3578 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3579 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3580 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3581 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3582 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3583 } 3584 3585 void Threads::initialize_jsr292_core_classes(TRAPS) { 3586 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3587 3588 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3589 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3590 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3591 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3592 } 3593 3594 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3595 extern void JDK_Version_init(); 3596 3597 // Preinitialize version info. 3598 VM_Version::early_initialize(); 3599 3600 // Check version 3601 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3602 3603 // Initialize library-based TLS 3604 ThreadLocalStorage::init(); 3605 3606 // Initialize the output stream module 3607 ostream_init(); 3608 3609 // Process java launcher properties. 3610 Arguments::process_sun_java_launcher_properties(args); 3611 3612 // Initialize the os module 3613 os::init(); 3614 3615 // Record VM creation timing statistics 3616 TraceVmCreationTime create_vm_timer; 3617 create_vm_timer.start(); 3618 3619 // Initialize system properties. 3620 Arguments::init_system_properties(); 3621 3622 // So that JDK version can be used as a discriminator when parsing arguments 3623 JDK_Version_init(); 3624 3625 // Update/Initialize System properties after JDK version number is known 3626 Arguments::init_version_specific_system_properties(); 3627 3628 // Make sure to initialize log configuration *before* parsing arguments 3629 LogConfiguration::initialize(create_vm_timer.begin_time()); 3630 3631 // Parse arguments 3632 // Note: this internally calls os::init_container_support() 3633 jint parse_result = Arguments::parse(args); 3634 if (parse_result != JNI_OK) return parse_result; 3635 3636 os::init_before_ergo(); 3637 3638 jint ergo_result = Arguments::apply_ergo(); 3639 if (ergo_result != JNI_OK) return ergo_result; 3640 3641 // Final check of all ranges after ergonomics which may change values. 3642 if (!JVMFlagRangeList::check_ranges()) { 3643 return JNI_EINVAL; 3644 } 3645 3646 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3647 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3648 if (!constraint_result) { 3649 return JNI_EINVAL; 3650 } 3651 3652 JVMFlagWriteableList::mark_startup(); 3653 3654 if (PauseAtStartup) { 3655 os::pause(); 3656 } 3657 3658 HOTSPOT_VM_INIT_BEGIN(); 3659 3660 // Timing (must come after argument parsing) 3661 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3662 3663 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3664 // Initialize assert poison page mechanism. 3665 if (ShowRegistersOnAssert) { 3666 initialize_assert_poison(); 3667 } 3668 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3669 3670 // Initialize the os module after parsing the args 3671 jint os_init_2_result = os::init_2(); 3672 if (os_init_2_result != JNI_OK) return os_init_2_result; 3673 3674 SafepointMechanism::initialize(); 3675 3676 jint adjust_after_os_result = Arguments::adjust_after_os(); 3677 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3678 3679 // Initialize output stream logging 3680 ostream_init_log(); 3681 3682 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3683 // Must be before create_vm_init_agents() 3684 if (Arguments::init_libraries_at_startup()) { 3685 convert_vm_init_libraries_to_agents(); 3686 } 3687 3688 // Launch -agentlib/-agentpath and converted -Xrun agents 3689 if (Arguments::init_agents_at_startup()) { 3690 create_vm_init_agents(); 3691 } 3692 3693 // Initialize Threads state 3694 _thread_list = NULL; 3695 _number_of_threads = 0; 3696 _number_of_non_daemon_threads = 0; 3697 3698 // Initialize global data structures and create system classes in heap 3699 vm_init_globals(); 3700 3701 #if INCLUDE_JVMCI 3702 if (JVMCICounterSize > 0) { 3703 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3704 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3705 } else { 3706 JavaThread::_jvmci_old_thread_counters = NULL; 3707 } 3708 #endif // INCLUDE_JVMCI 3709 3710 // Attach the main thread to this os thread 3711 JavaThread* main_thread = new JavaThread(); 3712 main_thread->set_thread_state(_thread_in_vm); 3713 main_thread->initialize_thread_current(); 3714 // must do this before set_active_handles 3715 main_thread->record_stack_base_and_size(); 3716 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3717 3718 if (!main_thread->set_as_starting_thread()) { 3719 vm_shutdown_during_initialization( 3720 "Failed necessary internal allocation. Out of swap space"); 3721 main_thread->smr_delete(); 3722 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3723 return JNI_ENOMEM; 3724 } 3725 3726 // Enable guard page *after* os::create_main_thread(), otherwise it would 3727 // crash Linux VM, see notes in os_linux.cpp. 3728 main_thread->create_stack_guard_pages(); 3729 3730 // Initialize Java-Level synchronization subsystem 3731 ObjectMonitor::Initialize(); 3732 3733 // Initialize global modules 3734 jint status = init_globals(); 3735 if (status != JNI_OK) { 3736 main_thread->smr_delete(); 3737 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3738 return status; 3739 } 3740 3741 if (TRACE_INITIALIZE() != JNI_OK) { 3742 vm_exit_during_initialization("Failed to initialize tracing backend"); 3743 } 3744 3745 // Should be done after the heap is fully created 3746 main_thread->cache_global_variables(); 3747 3748 HandleMark hm; 3749 3750 { MutexLocker mu(Threads_lock); 3751 Threads::add(main_thread); 3752 } 3753 3754 // Any JVMTI raw monitors entered in onload will transition into 3755 // real raw monitor. VM is setup enough here for raw monitor enter. 3756 JvmtiExport::transition_pending_onload_raw_monitors(); 3757 3758 // Create the VMThread 3759 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3760 3761 VMThread::create(); 3762 Thread* vmthread = VMThread::vm_thread(); 3763 3764 if (!os::create_thread(vmthread, os::vm_thread)) { 3765 vm_exit_during_initialization("Cannot create VM thread. " 3766 "Out of system resources."); 3767 } 3768 3769 // Wait for the VM thread to become ready, and VMThread::run to initialize 3770 // Monitors can have spurious returns, must always check another state flag 3771 { 3772 MutexLocker ml(Notify_lock); 3773 os::start_thread(vmthread); 3774 while (vmthread->active_handles() == NULL) { 3775 Notify_lock->wait(); 3776 } 3777 } 3778 } 3779 3780 assert(Universe::is_fully_initialized(), "not initialized"); 3781 if (VerifyDuringStartup) { 3782 // Make sure we're starting with a clean slate. 3783 VM_Verify verify_op; 3784 VMThread::execute(&verify_op); 3785 } 3786 3787 Thread* THREAD = Thread::current(); 3788 3789 // Always call even when there are not JVMTI environments yet, since environments 3790 // may be attached late and JVMTI must track phases of VM execution 3791 JvmtiExport::enter_early_start_phase(); 3792 3793 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3794 JvmtiExport::post_early_vm_start(); 3795 3796 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3797 3798 // We need this for ClassDataSharing - the initial vm.info property is set 3799 // with the default value of CDS "sharing" which may be reset through 3800 // command line options. 3801 reset_vm_info_property(CHECK_JNI_ERR); 3802 3803 quicken_jni_functions(); 3804 3805 // No more stub generation allowed after that point. 3806 StubCodeDesc::freeze(); 3807 3808 // Set flag that basic initialization has completed. Used by exceptions and various 3809 // debug stuff, that does not work until all basic classes have been initialized. 3810 set_init_completed(); 3811 3812 LogConfiguration::post_initialize(); 3813 Metaspace::post_initialize(); 3814 3815 HOTSPOT_VM_INIT_END(); 3816 3817 // record VM initialization completion time 3818 #if INCLUDE_MANAGEMENT 3819 Management::record_vm_init_completed(); 3820 #endif // INCLUDE_MANAGEMENT 3821 3822 // Signal Dispatcher needs to be started before VMInit event is posted 3823 os::signal_init(CHECK_JNI_ERR); 3824 3825 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3826 if (!DisableAttachMechanism) { 3827 AttachListener::vm_start(); 3828 if (StartAttachListener || AttachListener::init_at_startup()) { 3829 AttachListener::init(); 3830 } 3831 } 3832 3833 // Launch -Xrun agents 3834 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3835 // back-end can launch with -Xdebug -Xrunjdwp. 3836 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3837 create_vm_init_libraries(); 3838 } 3839 3840 if (CleanChunkPoolAsync) { 3841 Chunk::start_chunk_pool_cleaner_task(); 3842 } 3843 3844 // initialize compiler(s) 3845 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3846 #if INCLUDE_JVMCI 3847 bool force_JVMCI_intialization = false; 3848 if (EnableJVMCI) { 3849 // Initialize JVMCI eagerly when it is explicitly requested. 3850 // Or when JVMCIPrintProperties is enabled. 3851 // The JVMCI Java initialization code will read this flag and 3852 // do the printing if it's set. 3853 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3854 3855 if (!force_JVMCI_intialization) { 3856 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3857 // compilations via JVMCI will not actually block until JVMCI is initialized. 3858 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3859 } 3860 } 3861 #endif 3862 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3863 // Postpone completion of compiler initialization to after JVMCI 3864 // is initialized to avoid timeouts of blocking compilations. 3865 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3866 CompileBroker::compilation_init_phase2(); 3867 } 3868 #endif 3869 3870 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3871 // It is done after compilers are initialized, because otherwise compilations of 3872 // signature polymorphic MH intrinsics can be missed 3873 // (see SystemDictionary::find_method_handle_intrinsic). 3874 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3875 3876 // This will initialize the module system. Only java.base classes can be 3877 // loaded until phase 2 completes 3878 call_initPhase2(CHECK_JNI_ERR); 3879 3880 // Always call even when there are not JVMTI environments yet, since environments 3881 // may be attached late and JVMTI must track phases of VM execution 3882 JvmtiExport::enter_start_phase(); 3883 3884 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3885 JvmtiExport::post_vm_start(); 3886 3887 // Final system initialization including security manager and system class loader 3888 call_initPhase3(CHECK_JNI_ERR); 3889 3890 // cache the system and platform class loaders 3891 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3892 3893 #if INCLUDE_JVMCI 3894 if (force_JVMCI_intialization) { 3895 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3896 CompileBroker::compilation_init_phase2(); 3897 } 3898 #endif 3899 3900 // Always call even when there are not JVMTI environments yet, since environments 3901 // may be attached late and JVMTI must track phases of VM execution 3902 JvmtiExport::enter_live_phase(); 3903 3904 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3905 JvmtiExport::post_vm_initialized(); 3906 3907 if (TRACE_START() != JNI_OK) { 3908 vm_exit_during_initialization("Failed to start tracing backend."); 3909 } 3910 3911 #if INCLUDE_MANAGEMENT 3912 Management::initialize(THREAD); 3913 3914 if (HAS_PENDING_EXCEPTION) { 3915 // management agent fails to start possibly due to 3916 // configuration problem and is responsible for printing 3917 // stack trace if appropriate. Simply exit VM. 3918 vm_exit(1); 3919 } 3920 #endif // INCLUDE_MANAGEMENT 3921 3922 if (MemProfiling) MemProfiler::engage(); 3923 StatSampler::engage(); 3924 if (CheckJNICalls) JniPeriodicChecker::engage(); 3925 3926 BiasedLocking::init(); 3927 3928 #if INCLUDE_RTM_OPT 3929 RTMLockingCounters::init(); 3930 #endif 3931 3932 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3933 call_postVMInitHook(THREAD); 3934 // The Java side of PostVMInitHook.run must deal with all 3935 // exceptions and provide means of diagnosis. 3936 if (HAS_PENDING_EXCEPTION) { 3937 CLEAR_PENDING_EXCEPTION; 3938 } 3939 } 3940 3941 { 3942 MutexLocker ml(PeriodicTask_lock); 3943 // Make sure the WatcherThread can be started by WatcherThread::start() 3944 // or by dynamic enrollment. 3945 WatcherThread::make_startable(); 3946 // Start up the WatcherThread if there are any periodic tasks 3947 // NOTE: All PeriodicTasks should be registered by now. If they 3948 // aren't, late joiners might appear to start slowly (we might 3949 // take a while to process their first tick). 3950 if (PeriodicTask::num_tasks() > 0) { 3951 WatcherThread::start(); 3952 } 3953 } 3954 3955 create_vm_timer.end(); 3956 #ifdef ASSERT 3957 _vm_complete = true; 3958 #endif 3959 3960 if (DumpSharedSpaces) { 3961 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3962 ShouldNotReachHere(); 3963 } 3964 3965 return JNI_OK; 3966 } 3967 3968 // type for the Agent_OnLoad and JVM_OnLoad entry points 3969 extern "C" { 3970 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3971 } 3972 // Find a command line agent library and return its entry point for 3973 // -agentlib: -agentpath: -Xrun 3974 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3975 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3976 const char *on_load_symbols[], 3977 size_t num_symbol_entries) { 3978 OnLoadEntry_t on_load_entry = NULL; 3979 void *library = NULL; 3980 3981 if (!agent->valid()) { 3982 char buffer[JVM_MAXPATHLEN]; 3983 char ebuf[1024] = ""; 3984 const char *name = agent->name(); 3985 const char *msg = "Could not find agent library "; 3986 3987 // First check to see if agent is statically linked into executable 3988 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3989 library = agent->os_lib(); 3990 } else if (agent->is_absolute_path()) { 3991 library = os::dll_load(name, ebuf, sizeof ebuf); 3992 if (library == NULL) { 3993 const char *sub_msg = " in absolute path, with error: "; 3994 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3995 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3996 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3997 // If we can't find the agent, exit. 3998 vm_exit_during_initialization(buf, NULL); 3999 FREE_C_HEAP_ARRAY(char, buf); 4000 } 4001 } else { 4002 // Try to load the agent from the standard dll directory 4003 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4004 name)) { 4005 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4006 } 4007 if (library == NULL) { // Try the library path directory. 4008 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4009 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4010 } 4011 if (library == NULL) { 4012 const char *sub_msg = " on the library path, with error: "; 4013 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4014 4015 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4016 strlen(ebuf) + strlen(sub_msg2) + 1; 4017 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4018 if (!agent->is_instrument_lib()) { 4019 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4020 } else { 4021 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4022 } 4023 // If we can't find the agent, exit. 4024 vm_exit_during_initialization(buf, NULL); 4025 FREE_C_HEAP_ARRAY(char, buf); 4026 } 4027 } 4028 } 4029 agent->set_os_lib(library); 4030 agent->set_valid(); 4031 } 4032 4033 // Find the OnLoad function. 4034 on_load_entry = 4035 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4036 false, 4037 on_load_symbols, 4038 num_symbol_entries)); 4039 return on_load_entry; 4040 } 4041 4042 // Find the JVM_OnLoad entry point 4043 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4044 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4045 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4046 } 4047 4048 // Find the Agent_OnLoad entry point 4049 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4050 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4051 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4052 } 4053 4054 // For backwards compatibility with -Xrun 4055 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4056 // treated like -agentpath: 4057 // Must be called before agent libraries are created 4058 void Threads::convert_vm_init_libraries_to_agents() { 4059 AgentLibrary* agent; 4060 AgentLibrary* next; 4061 4062 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4063 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4064 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4065 4066 // If there is an JVM_OnLoad function it will get called later, 4067 // otherwise see if there is an Agent_OnLoad 4068 if (on_load_entry == NULL) { 4069 on_load_entry = lookup_agent_on_load(agent); 4070 if (on_load_entry != NULL) { 4071 // switch it to the agent list -- so that Agent_OnLoad will be called, 4072 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4073 Arguments::convert_library_to_agent(agent); 4074 } else { 4075 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4076 } 4077 } 4078 } 4079 } 4080 4081 // Create agents for -agentlib: -agentpath: and converted -Xrun 4082 // Invokes Agent_OnLoad 4083 // Called very early -- before JavaThreads exist 4084 void Threads::create_vm_init_agents() { 4085 extern struct JavaVM_ main_vm; 4086 AgentLibrary* agent; 4087 4088 JvmtiExport::enter_onload_phase(); 4089 4090 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4091 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4092 4093 if (on_load_entry != NULL) { 4094 // Invoke the Agent_OnLoad function 4095 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4096 if (err != JNI_OK) { 4097 vm_exit_during_initialization("agent library failed to init", agent->name()); 4098 } 4099 } else { 4100 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4101 } 4102 } 4103 JvmtiExport::enter_primordial_phase(); 4104 } 4105 4106 extern "C" { 4107 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4108 } 4109 4110 void Threads::shutdown_vm_agents() { 4111 // Send any Agent_OnUnload notifications 4112 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4113 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4114 extern struct JavaVM_ main_vm; 4115 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4116 4117 // Find the Agent_OnUnload function. 4118 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4119 os::find_agent_function(agent, 4120 false, 4121 on_unload_symbols, 4122 num_symbol_entries)); 4123 4124 // Invoke the Agent_OnUnload function 4125 if (unload_entry != NULL) { 4126 JavaThread* thread = JavaThread::current(); 4127 ThreadToNativeFromVM ttn(thread); 4128 HandleMark hm(thread); 4129 (*unload_entry)(&main_vm); 4130 } 4131 } 4132 } 4133 4134 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4135 // Invokes JVM_OnLoad 4136 void Threads::create_vm_init_libraries() { 4137 extern struct JavaVM_ main_vm; 4138 AgentLibrary* agent; 4139 4140 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4141 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4142 4143 if (on_load_entry != NULL) { 4144 // Invoke the JVM_OnLoad function 4145 JavaThread* thread = JavaThread::current(); 4146 ThreadToNativeFromVM ttn(thread); 4147 HandleMark hm(thread); 4148 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4149 if (err != JNI_OK) { 4150 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4151 } 4152 } else { 4153 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4154 } 4155 } 4156 } 4157 4158 4159 // Last thread running calls java.lang.Shutdown.shutdown() 4160 void JavaThread::invoke_shutdown_hooks() { 4161 HandleMark hm(this); 4162 4163 // We could get here with a pending exception, if so clear it now. 4164 if (this->has_pending_exception()) { 4165 this->clear_pending_exception(); 4166 } 4167 4168 EXCEPTION_MARK; 4169 Klass* shutdown_klass = 4170 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4171 THREAD); 4172 if (shutdown_klass != NULL) { 4173 // SystemDictionary::resolve_or_null will return null if there was 4174 // an exception. If we cannot load the Shutdown class, just don't 4175 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4176 // won't be run. Note that if a shutdown hook was registered, 4177 // the Shutdown class would have already been loaded 4178 // (Runtime.addShutdownHook will load it). 4179 JavaValue result(T_VOID); 4180 JavaCalls::call_static(&result, 4181 shutdown_klass, 4182 vmSymbols::shutdown_method_name(), 4183 vmSymbols::void_method_signature(), 4184 THREAD); 4185 } 4186 CLEAR_PENDING_EXCEPTION; 4187 } 4188 4189 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4190 // the program falls off the end of main(). Another VM exit path is through 4191 // vm_exit() when the program calls System.exit() to return a value or when 4192 // there is a serious error in VM. The two shutdown paths are not exactly 4193 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4194 // and VM_Exit op at VM level. 4195 // 4196 // Shutdown sequence: 4197 // + Shutdown native memory tracking if it is on 4198 // + Wait until we are the last non-daemon thread to execute 4199 // <-- every thing is still working at this moment --> 4200 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4201 // shutdown hooks 4202 // + Call before_exit(), prepare for VM exit 4203 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4204 // currently the only user of this mechanism is File.deleteOnExit()) 4205 // > stop StatSampler, watcher thread, CMS threads, 4206 // post thread end and vm death events to JVMTI, 4207 // stop signal thread 4208 // + Call JavaThread::exit(), it will: 4209 // > release JNI handle blocks, remove stack guard pages 4210 // > remove this thread from Threads list 4211 // <-- no more Java code from this thread after this point --> 4212 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4213 // the compiler threads at safepoint 4214 // <-- do not use anything that could get blocked by Safepoint --> 4215 // + Disable tracing at JNI/JVM barriers 4216 // + Set _vm_exited flag for threads that are still running native code 4217 // + Delete this thread 4218 // + Call exit_globals() 4219 // > deletes tty 4220 // > deletes PerfMemory resources 4221 // + Return to caller 4222 4223 bool Threads::destroy_vm() { 4224 JavaThread* thread = JavaThread::current(); 4225 4226 #ifdef ASSERT 4227 _vm_complete = false; 4228 #endif 4229 // Wait until we are the last non-daemon thread to execute 4230 { MutexLocker nu(Threads_lock); 4231 while (Threads::number_of_non_daemon_threads() > 1) 4232 // This wait should make safepoint checks, wait without a timeout, 4233 // and wait as a suspend-equivalent condition. 4234 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4235 Mutex::_as_suspend_equivalent_flag); 4236 } 4237 4238 EventShutdown e; 4239 if (e.should_commit()) { 4240 e.set_reason("No remaining non-daemon Java threads"); 4241 e.commit(); 4242 } 4243 4244 // Hang forever on exit if we are reporting an error. 4245 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4246 os::infinite_sleep(); 4247 } 4248 os::wait_for_keypress_at_exit(); 4249 4250 // run Java level shutdown hooks 4251 thread->invoke_shutdown_hooks(); 4252 4253 before_exit(thread); 4254 4255 thread->exit(true); 4256 4257 // Stop VM thread. 4258 { 4259 // 4945125 The vm thread comes to a safepoint during exit. 4260 // GC vm_operations can get caught at the safepoint, and the 4261 // heap is unparseable if they are caught. Grab the Heap_lock 4262 // to prevent this. The GC vm_operations will not be able to 4263 // queue until after the vm thread is dead. After this point, 4264 // we'll never emerge out of the safepoint before the VM exits. 4265 4266 MutexLocker ml(Heap_lock); 4267 4268 VMThread::wait_for_vm_thread_exit(); 4269 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4270 VMThread::destroy(); 4271 } 4272 4273 // Now, all Java threads are gone except daemon threads. Daemon threads 4274 // running Java code or in VM are stopped by the Safepoint. However, 4275 // daemon threads executing native code are still running. But they 4276 // will be stopped at native=>Java/VM barriers. Note that we can't 4277 // simply kill or suspend them, as it is inherently deadlock-prone. 4278 4279 VM_Exit::set_vm_exited(); 4280 4281 // Clean up ideal graph printers after the VMThread has started 4282 // the final safepoint which will block all the Compiler threads. 4283 // Note that this Thread has already logically exited so the 4284 // clean_up() function's use of a JavaThreadIteratorWithHandle 4285 // would be a problem except set_vm_exited() has remembered the 4286 // shutdown thread which is granted a policy exception. 4287 #if defined(COMPILER2) && !defined(PRODUCT) 4288 IdealGraphPrinter::clean_up(); 4289 #endif 4290 4291 notify_vm_shutdown(); 4292 4293 // We are after VM_Exit::set_vm_exited() so we can't call 4294 // thread->smr_delete() or we will block on the Threads_lock. 4295 // Deleting the shutdown thread here is safe because another 4296 // JavaThread cannot have an active ThreadsListHandle for 4297 // this JavaThread. 4298 delete thread; 4299 4300 #if INCLUDE_JVMCI 4301 if (JVMCICounterSize > 0) { 4302 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4303 } 4304 #endif 4305 4306 // exit_globals() will delete tty 4307 exit_globals(); 4308 4309 LogConfiguration::finalize(); 4310 4311 return true; 4312 } 4313 4314 4315 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4316 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4317 return is_supported_jni_version(version); 4318 } 4319 4320 4321 jboolean Threads::is_supported_jni_version(jint version) { 4322 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4323 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4324 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4325 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4326 if (version == JNI_VERSION_9) return JNI_TRUE; 4327 if (version == JNI_VERSION_10) return JNI_TRUE; 4328 return JNI_FALSE; 4329 } 4330 4331 4332 void Threads::add(JavaThread* p, bool force_daemon) { 4333 // The threads lock must be owned at this point 4334 assert_locked_or_safepoint(Threads_lock); 4335 4336 BarrierSet::barrier_set()->on_thread_attach(p); 4337 4338 p->set_next(_thread_list); 4339 _thread_list = p; 4340 4341 // Once a JavaThread is added to the Threads list, smr_delete() has 4342 // to be used to delete it. Otherwise we can just delete it directly. 4343 p->set_on_thread_list(); 4344 4345 _number_of_threads++; 4346 oop threadObj = p->threadObj(); 4347 bool daemon = true; 4348 // Bootstrapping problem: threadObj can be null for initial 4349 // JavaThread (or for threads attached via JNI) 4350 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4351 _number_of_non_daemon_threads++; 4352 daemon = false; 4353 } 4354 4355 ThreadService::add_thread(p, daemon); 4356 4357 // Maintain fast thread list 4358 ThreadsSMRSupport::add_thread(p); 4359 4360 // Possible GC point. 4361 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4362 } 4363 4364 void Threads::remove(JavaThread* p) { 4365 4366 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4367 ObjectSynchronizer::omFlush(p); 4368 4369 // Extra scope needed for Thread_lock, so we can check 4370 // that we do not remove thread without safepoint code notice 4371 { MutexLocker ml(Threads_lock); 4372 4373 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4374 4375 // Maintain fast thread list 4376 ThreadsSMRSupport::remove_thread(p); 4377 4378 JavaThread* current = _thread_list; 4379 JavaThread* prev = NULL; 4380 4381 while (current != p) { 4382 prev = current; 4383 current = current->next(); 4384 } 4385 4386 if (prev) { 4387 prev->set_next(current->next()); 4388 } else { 4389 _thread_list = p->next(); 4390 } 4391 4392 _number_of_threads--; 4393 oop threadObj = p->threadObj(); 4394 bool daemon = true; 4395 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4396 _number_of_non_daemon_threads--; 4397 daemon = false; 4398 4399 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4400 // on destroy_vm will wake up. 4401 if (number_of_non_daemon_threads() == 1) { 4402 Threads_lock->notify_all(); 4403 } 4404 } 4405 ThreadService::remove_thread(p, daemon); 4406 4407 // Make sure that safepoint code disregard this thread. This is needed since 4408 // the thread might mess around with locks after this point. This can cause it 4409 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4410 // of this thread since it is removed from the queue. 4411 p->set_terminated_value(); 4412 } // unlock Threads_lock 4413 4414 // Since Events::log uses a lock, we grab it outside the Threads_lock 4415 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4416 } 4417 4418 // Operations on the Threads list for GC. These are not explicitly locked, 4419 // but the garbage collector must provide a safe context for them to run. 4420 // In particular, these things should never be called when the Threads_lock 4421 // is held by some other thread. (Note: the Safepoint abstraction also 4422 // uses the Threads_lock to guarantee this property. It also makes sure that 4423 // all threads gets blocked when exiting or starting). 4424 4425 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4426 ALL_JAVA_THREADS(p) { 4427 p->oops_do(f, cf); 4428 } 4429 VMThread::vm_thread()->oops_do(f, cf); 4430 } 4431 4432 void Threads::change_thread_claim_parity() { 4433 // Set the new claim parity. 4434 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4435 "Not in range."); 4436 _thread_claim_parity++; 4437 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4438 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4439 "Not in range."); 4440 } 4441 4442 #ifdef ASSERT 4443 void Threads::assert_all_threads_claimed() { 4444 ALL_JAVA_THREADS(p) { 4445 const int thread_parity = p->oops_do_parity(); 4446 assert((thread_parity == _thread_claim_parity), 4447 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4448 } 4449 VMThread* vmt = VMThread::vm_thread(); 4450 const int thread_parity = vmt->oops_do_parity(); 4451 assert((thread_parity == _thread_claim_parity), 4452 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4453 } 4454 #endif // ASSERT 4455 4456 class ParallelOopsDoThreadClosure : public ThreadClosure { 4457 private: 4458 OopClosure* _f; 4459 CodeBlobClosure* _cf; 4460 public: 4461 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4462 void do_thread(Thread* t) { 4463 t->oops_do(_f, _cf); 4464 } 4465 }; 4466 4467 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4468 ParallelOopsDoThreadClosure tc(f, cf); 4469 possibly_parallel_threads_do(is_par, &tc); 4470 } 4471 4472 #if INCLUDE_ALL_GCS 4473 // Used by ParallelScavenge 4474 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4475 ALL_JAVA_THREADS(p) { 4476 q->enqueue(new ThreadRootsTask(p)); 4477 } 4478 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4479 } 4480 4481 // Used by Parallel Old 4482 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4483 ALL_JAVA_THREADS(p) { 4484 q->enqueue(new ThreadRootsMarkingTask(p)); 4485 } 4486 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4487 } 4488 #endif // INCLUDE_ALL_GCS 4489 4490 void Threads::nmethods_do(CodeBlobClosure* cf) { 4491 ALL_JAVA_THREADS(p) { 4492 // This is used by the code cache sweeper to mark nmethods that are active 4493 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4494 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4495 if(!p->is_Code_cache_sweeper_thread()) { 4496 p->nmethods_do(cf); 4497 } 4498 } 4499 } 4500 4501 void Threads::metadata_do(void f(Metadata*)) { 4502 ALL_JAVA_THREADS(p) { 4503 p->metadata_do(f); 4504 } 4505 } 4506 4507 class ThreadHandlesClosure : public ThreadClosure { 4508 void (*_f)(Metadata*); 4509 public: 4510 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4511 virtual void do_thread(Thread* thread) { 4512 thread->metadata_handles_do(_f); 4513 } 4514 }; 4515 4516 void Threads::metadata_handles_do(void f(Metadata*)) { 4517 // Only walk the Handles in Thread. 4518 ThreadHandlesClosure handles_closure(f); 4519 threads_do(&handles_closure); 4520 } 4521 4522 void Threads::deoptimized_wrt_marked_nmethods() { 4523 ALL_JAVA_THREADS(p) { 4524 p->deoptimized_wrt_marked_nmethods(); 4525 } 4526 } 4527 4528 4529 // Get count Java threads that are waiting to enter the specified monitor. 4530 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4531 int count, 4532 address monitor) { 4533 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4534 4535 int i = 0; 4536 DO_JAVA_THREADS(t_list, p) { 4537 if (!p->can_call_java()) continue; 4538 4539 address pending = (address)p->current_pending_monitor(); 4540 if (pending == monitor) { // found a match 4541 if (i < count) result->append(p); // save the first count matches 4542 i++; 4543 } 4544 } 4545 4546 return result; 4547 } 4548 4549 4550 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4551 address owner) { 4552 // NULL owner means not locked so we can skip the search 4553 if (owner == NULL) return NULL; 4554 4555 DO_JAVA_THREADS(t_list, p) { 4556 // first, see if owner is the address of a Java thread 4557 if (owner == (address)p) return p; 4558 } 4559 4560 // Cannot assert on lack of success here since this function may be 4561 // used by code that is trying to report useful problem information 4562 // like deadlock detection. 4563 if (UseHeavyMonitors) return NULL; 4564 4565 // If we didn't find a matching Java thread and we didn't force use of 4566 // heavyweight monitors, then the owner is the stack address of the 4567 // Lock Word in the owning Java thread's stack. 4568 // 4569 JavaThread* the_owner = NULL; 4570 DO_JAVA_THREADS(t_list, q) { 4571 if (q->is_lock_owned(owner)) { 4572 the_owner = q; 4573 break; 4574 } 4575 } 4576 4577 // cannot assert on lack of success here; see above comment 4578 return the_owner; 4579 } 4580 4581 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4582 void Threads::print_on(outputStream* st, bool print_stacks, 4583 bool internal_format, bool print_concurrent_locks) { 4584 char buf[32]; 4585 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4586 4587 st->print_cr("Full thread dump %s (%s %s):", 4588 Abstract_VM_Version::vm_name(), 4589 Abstract_VM_Version::vm_release(), 4590 Abstract_VM_Version::vm_info_string()); 4591 st->cr(); 4592 4593 #if INCLUDE_SERVICES 4594 // Dump concurrent locks 4595 ConcurrentLocksDump concurrent_locks; 4596 if (print_concurrent_locks) { 4597 concurrent_locks.dump_at_safepoint(); 4598 } 4599 #endif // INCLUDE_SERVICES 4600 4601 ThreadsSMRSupport::print_info_on(st); 4602 st->cr(); 4603 4604 ALL_JAVA_THREADS(p) { 4605 ResourceMark rm; 4606 p->print_on(st); 4607 if (print_stacks) { 4608 if (internal_format) { 4609 p->trace_stack(); 4610 } else { 4611 p->print_stack_on(st); 4612 } 4613 } 4614 st->cr(); 4615 #if INCLUDE_SERVICES 4616 if (print_concurrent_locks) { 4617 concurrent_locks.print_locks_on(p, st); 4618 } 4619 #endif // INCLUDE_SERVICES 4620 } 4621 4622 VMThread::vm_thread()->print_on(st); 4623 st->cr(); 4624 Universe::heap()->print_gc_threads_on(st); 4625 WatcherThread* wt = WatcherThread::watcher_thread(); 4626 if (wt != NULL) { 4627 wt->print_on(st); 4628 st->cr(); 4629 } 4630 4631 st->flush(); 4632 } 4633 4634 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4635 int buflen, bool* found_current) { 4636 if (this_thread != NULL) { 4637 bool is_current = (current == this_thread); 4638 *found_current = *found_current || is_current; 4639 st->print("%s", is_current ? "=>" : " "); 4640 4641 st->print(PTR_FORMAT, p2i(this_thread)); 4642 st->print(" "); 4643 this_thread->print_on_error(st, buf, buflen); 4644 st->cr(); 4645 } 4646 } 4647 4648 class PrintOnErrorClosure : public ThreadClosure { 4649 outputStream* _st; 4650 Thread* _current; 4651 char* _buf; 4652 int _buflen; 4653 bool* _found_current; 4654 public: 4655 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4656 int buflen, bool* found_current) : 4657 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4658 4659 virtual void do_thread(Thread* thread) { 4660 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4661 } 4662 }; 4663 4664 // Threads::print_on_error() is called by fatal error handler. It's possible 4665 // that VM is not at safepoint and/or current thread is inside signal handler. 4666 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4667 // memory (even in resource area), it might deadlock the error handler. 4668 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4669 int buflen) { 4670 ThreadsSMRSupport::print_info_on(st); 4671 st->cr(); 4672 4673 bool found_current = false; 4674 st->print_cr("Java Threads: ( => current thread )"); 4675 ALL_JAVA_THREADS(thread) { 4676 print_on_error(thread, st, current, buf, buflen, &found_current); 4677 } 4678 st->cr(); 4679 4680 st->print_cr("Other Threads:"); 4681 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4682 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4683 4684 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4685 Universe::heap()->gc_threads_do(&print_closure); 4686 4687 if (!found_current) { 4688 st->cr(); 4689 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4690 current->print_on_error(st, buf, buflen); 4691 st->cr(); 4692 } 4693 st->cr(); 4694 4695 st->print_cr("Threads with active compile tasks:"); 4696 print_threads_compiling(st, buf, buflen); 4697 } 4698 4699 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4700 ALL_JAVA_THREADS(thread) { 4701 if (thread->is_Compiler_thread()) { 4702 CompilerThread* ct = (CompilerThread*) thread; 4703 4704 // Keep task in local variable for NULL check. 4705 // ct->_task might be set to NULL by concurring compiler thread 4706 // because it completed the compilation. The task is never freed, 4707 // though, just returned to a free list. 4708 CompileTask* task = ct->task(); 4709 if (task != NULL) { 4710 thread->print_name_on_error(st, buf, buflen); 4711 task->print(st, NULL, true, true); 4712 } 4713 } 4714 } 4715 } 4716 4717 4718 // Internal SpinLock and Mutex 4719 // Based on ParkEvent 4720 4721 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4722 // 4723 // We employ SpinLocks _only for low-contention, fixed-length 4724 // short-duration critical sections where we're concerned 4725 // about native mutex_t or HotSpot Mutex:: latency. 4726 // The mux construct provides a spin-then-block mutual exclusion 4727 // mechanism. 4728 // 4729 // Testing has shown that contention on the ListLock guarding gFreeList 4730 // is common. If we implement ListLock as a simple SpinLock it's common 4731 // for the JVM to devolve to yielding with little progress. This is true 4732 // despite the fact that the critical sections protected by ListLock are 4733 // extremely short. 4734 // 4735 // TODO-FIXME: ListLock should be of type SpinLock. 4736 // We should make this a 1st-class type, integrated into the lock 4737 // hierarchy as leaf-locks. Critically, the SpinLock structure 4738 // should have sufficient padding to avoid false-sharing and excessive 4739 // cache-coherency traffic. 4740 4741 4742 typedef volatile int SpinLockT; 4743 4744 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4745 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4746 return; // normal fast-path return 4747 } 4748 4749 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4750 TEVENT(SpinAcquire - ctx); 4751 int ctr = 0; 4752 int Yields = 0; 4753 for (;;) { 4754 while (*adr != 0) { 4755 ++ctr; 4756 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4757 if (Yields > 5) { 4758 os::naked_short_sleep(1); 4759 } else { 4760 os::naked_yield(); 4761 ++Yields; 4762 } 4763 } else { 4764 SpinPause(); 4765 } 4766 } 4767 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4768 } 4769 } 4770 4771 void Thread::SpinRelease(volatile int * adr) { 4772 assert(*adr != 0, "invariant"); 4773 OrderAccess::fence(); // guarantee at least release consistency. 4774 // Roach-motel semantics. 4775 // It's safe if subsequent LDs and STs float "up" into the critical section, 4776 // but prior LDs and STs within the critical section can't be allowed 4777 // to reorder or float past the ST that releases the lock. 4778 // Loads and stores in the critical section - which appear in program 4779 // order before the store that releases the lock - must also appear 4780 // before the store that releases the lock in memory visibility order. 4781 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4782 // the ST of 0 into the lock-word which releases the lock, so fence 4783 // more than covers this on all platforms. 4784 *adr = 0; 4785 } 4786 4787 // muxAcquire and muxRelease: 4788 // 4789 // * muxAcquire and muxRelease support a single-word lock-word construct. 4790 // The LSB of the word is set IFF the lock is held. 4791 // The remainder of the word points to the head of a singly-linked list 4792 // of threads blocked on the lock. 4793 // 4794 // * The current implementation of muxAcquire-muxRelease uses its own 4795 // dedicated Thread._MuxEvent instance. If we're interested in 4796 // minimizing the peak number of extant ParkEvent instances then 4797 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4798 // as certain invariants were satisfied. Specifically, care would need 4799 // to be taken with regards to consuming unpark() "permits". 4800 // A safe rule of thumb is that a thread would never call muxAcquire() 4801 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4802 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4803 // consume an unpark() permit intended for monitorenter, for instance. 4804 // One way around this would be to widen the restricted-range semaphore 4805 // implemented in park(). Another alternative would be to provide 4806 // multiple instances of the PlatformEvent() for each thread. One 4807 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4808 // 4809 // * Usage: 4810 // -- Only as leaf locks 4811 // -- for short-term locking only as muxAcquire does not perform 4812 // thread state transitions. 4813 // 4814 // Alternatives: 4815 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4816 // but with parking or spin-then-park instead of pure spinning. 4817 // * Use Taura-Oyama-Yonenzawa locks. 4818 // * It's possible to construct a 1-0 lock if we encode the lockword as 4819 // (List,LockByte). Acquire will CAS the full lockword while Release 4820 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4821 // acquiring threads use timers (ParkTimed) to detect and recover from 4822 // the stranding window. Thread/Node structures must be aligned on 256-byte 4823 // boundaries by using placement-new. 4824 // * Augment MCS with advisory back-link fields maintained with CAS(). 4825 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4826 // The validity of the backlinks must be ratified before we trust the value. 4827 // If the backlinks are invalid the exiting thread must back-track through the 4828 // the forward links, which are always trustworthy. 4829 // * Add a successor indication. The LockWord is currently encoded as 4830 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4831 // to provide the usual futile-wakeup optimization. 4832 // See RTStt for details. 4833 // * Consider schedctl.sc_nopreempt to cover the critical section. 4834 // 4835 4836 4837 const intptr_t LOCKBIT = 1; 4838 4839 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4840 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4841 if (w == 0) return; 4842 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4843 return; 4844 } 4845 4846 TEVENT(muxAcquire - Contention); 4847 ParkEvent * const Self = Thread::current()->_MuxEvent; 4848 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4849 for (;;) { 4850 int its = (os::is_MP() ? 100 : 0) + 1; 4851 4852 // Optional spin phase: spin-then-park strategy 4853 while (--its >= 0) { 4854 w = *Lock; 4855 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4856 return; 4857 } 4858 } 4859 4860 Self->reset(); 4861 Self->OnList = intptr_t(Lock); 4862 // The following fence() isn't _strictly necessary as the subsequent 4863 // CAS() both serializes execution and ratifies the fetched *Lock value. 4864 OrderAccess::fence(); 4865 for (;;) { 4866 w = *Lock; 4867 if ((w & LOCKBIT) == 0) { 4868 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4869 Self->OnList = 0; // hygiene - allows stronger asserts 4870 return; 4871 } 4872 continue; // Interference -- *Lock changed -- Just retry 4873 } 4874 assert(w & LOCKBIT, "invariant"); 4875 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4876 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4877 } 4878 4879 while (Self->OnList != 0) { 4880 Self->park(); 4881 } 4882 } 4883 } 4884 4885 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4886 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4887 if (w == 0) return; 4888 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4889 return; 4890 } 4891 4892 TEVENT(muxAcquire - Contention); 4893 ParkEvent * ReleaseAfter = NULL; 4894 if (ev == NULL) { 4895 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4896 } 4897 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4898 for (;;) { 4899 guarantee(ev->OnList == 0, "invariant"); 4900 int its = (os::is_MP() ? 100 : 0) + 1; 4901 4902 // Optional spin phase: spin-then-park strategy 4903 while (--its >= 0) { 4904 w = *Lock; 4905 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4906 if (ReleaseAfter != NULL) { 4907 ParkEvent::Release(ReleaseAfter); 4908 } 4909 return; 4910 } 4911 } 4912 4913 ev->reset(); 4914 ev->OnList = intptr_t(Lock); 4915 // The following fence() isn't _strictly necessary as the subsequent 4916 // CAS() both serializes execution and ratifies the fetched *Lock value. 4917 OrderAccess::fence(); 4918 for (;;) { 4919 w = *Lock; 4920 if ((w & LOCKBIT) == 0) { 4921 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4922 ev->OnList = 0; 4923 // We call ::Release while holding the outer lock, thus 4924 // artificially lengthening the critical section. 4925 // Consider deferring the ::Release() until the subsequent unlock(), 4926 // after we've dropped the outer lock. 4927 if (ReleaseAfter != NULL) { 4928 ParkEvent::Release(ReleaseAfter); 4929 } 4930 return; 4931 } 4932 continue; // Interference -- *Lock changed -- Just retry 4933 } 4934 assert(w & LOCKBIT, "invariant"); 4935 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4936 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4937 } 4938 4939 while (ev->OnList != 0) { 4940 ev->park(); 4941 } 4942 } 4943 } 4944 4945 // Release() must extract a successor from the list and then wake that thread. 4946 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4947 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4948 // Release() would : 4949 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4950 // (B) Extract a successor from the private list "in-hand" 4951 // (C) attempt to CAS() the residual back into *Lock over null. 4952 // If there were any newly arrived threads and the CAS() would fail. 4953 // In that case Release() would detach the RATs, re-merge the list in-hand 4954 // with the RATs and repeat as needed. Alternately, Release() might 4955 // detach and extract a successor, but then pass the residual list to the wakee. 4956 // The wakee would be responsible for reattaching and remerging before it 4957 // competed for the lock. 4958 // 4959 // Both "pop" and DMR are immune from ABA corruption -- there can be 4960 // multiple concurrent pushers, but only one popper or detacher. 4961 // This implementation pops from the head of the list. This is unfair, 4962 // but tends to provide excellent throughput as hot threads remain hot. 4963 // (We wake recently run threads first). 4964 // 4965 // All paths through muxRelease() will execute a CAS. 4966 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4967 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4968 // executed within the critical section are complete and globally visible before the 4969 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4970 void Thread::muxRelease(volatile intptr_t * Lock) { 4971 for (;;) { 4972 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4973 assert(w & LOCKBIT, "invariant"); 4974 if (w == LOCKBIT) return; 4975 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4976 assert(List != NULL, "invariant"); 4977 assert(List->OnList == intptr_t(Lock), "invariant"); 4978 ParkEvent * const nxt = List->ListNext; 4979 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4980 4981 // The following CAS() releases the lock and pops the head element. 4982 // The CAS() also ratifies the previously fetched lock-word value. 4983 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4984 continue; 4985 } 4986 List->OnList = 0; 4987 OrderAccess::fence(); 4988 List->unpark(); 4989 return; 4990 } 4991 } 4992 4993 4994 void Threads::verify() { 4995 ALL_JAVA_THREADS(p) { 4996 p->verify(); 4997 } 4998 VMThread* thread = VMThread::vm_thread(); 4999 if (thread != NULL) thread->verify(); 5000 }