1 /* 2 * Copyright (c) 2001, 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 #ifndef SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP 27 28 #include "gc/shared/gcCause.hpp" 29 #include "gc/shared/gcWhen.hpp" 30 #include "memory/allocation.hpp" 31 #include "runtime/handles.hpp" 32 #include "runtime/perfData.hpp" 33 #include "runtime/safepoint.hpp" 34 #include "utilities/debug.hpp" 35 #include "utilities/events.hpp" 36 #include "utilities/formatBuffer.hpp" 37 #include "utilities/growableArray.hpp" 38 #include "utilities/macros.hpp" 39 40 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 41 // is an abstract class: there may be many different kinds of heaps. This 42 // class defines the functions that a heap must implement, and contains 43 // infrastructure common to all heaps. 44 45 class AdaptiveSizePolicy; 46 class BarrierSet; 47 class CollectorPolicy; 48 class GCHeapSummary; 49 class GCTimer; 50 class GCTracer; 51 class GCMemoryManager; 52 class MemoryPool; 53 class MetaspaceSummary; 54 class SoftRefPolicy; 55 class Thread; 56 class ThreadClosure; 57 class VirtualSpaceSummary; 58 class WorkGang; 59 class nmethod; 60 61 class GCMessage : public FormatBuffer<1024> { 62 public: 63 bool is_before; 64 65 public: GCMessage()66 GCMessage() {} 67 }; 68 69 class CollectedHeap; 70 71 class GCHeapLog : public EventLogBase<GCMessage> { 72 private: 73 void log_heap(CollectedHeap* heap, bool before); 74 75 public: GCHeapLog()76 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {} 77 log_heap_before(CollectedHeap * heap)78 void log_heap_before(CollectedHeap* heap) { 79 log_heap(heap, true); 80 } log_heap_after(CollectedHeap * heap)81 void log_heap_after(CollectedHeap* heap) { 82 log_heap(heap, false); 83 } 84 }; 85 86 // 87 // CollectedHeap 88 // GenCollectedHeap 89 // SerialHeap 90 // CMSHeap 91 // G1CollectedHeap 92 // ParallelScavengeHeap 93 // ShenandoahHeap 94 // ZCollectedHeap 95 // 96 class CollectedHeap : public CHeapObj<mtInternal> { 97 friend class VMStructs; 98 friend class JVMCIVMStructs; 99 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 100 friend class MemAllocator; 101 102 private: 103 #ifdef ASSERT 104 static int _fire_out_of_memory_count; 105 #endif 106 107 GCHeapLog* _gc_heap_log; 108 109 MemRegion _reserved; 110 111 protected: 112 bool _is_gc_active; 113 114 // Used for filler objects (static, but initialized in ctor). 115 static size_t _filler_array_max_size; 116 117 unsigned int _total_collections; // ... started 118 unsigned int _total_full_collections; // ... started 119 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 120 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 121 122 // Reason for current garbage collection. Should be set to 123 // a value reflecting no collection between collections. 124 GCCause::Cause _gc_cause; 125 GCCause::Cause _gc_lastcause; 126 PerfStringVariable* _perf_gc_cause; 127 PerfStringVariable* _perf_gc_lastcause; 128 129 // Constructor 130 CollectedHeap(); 131 132 // Create a new tlab. All TLAB allocations must go through this. 133 // To allow more flexible TLAB allocations min_size specifies 134 // the minimum size needed, while requested_size is the requested 135 // size based on ergonomics. The actually allocated size will be 136 // returned in actual_size. 137 virtual HeapWord* allocate_new_tlab(size_t min_size, 138 size_t requested_size, 139 size_t* actual_size); 140 141 // Accumulate statistics on all tlabs. 142 virtual void accumulate_statistics_all_tlabs(); 143 144 // Reinitialize tlabs before resuming mutators. 145 virtual void resize_all_tlabs(); 146 147 // Raw memory allocation facilities 148 // The obj and array allocate methods are covers for these methods. 149 // mem_allocate() should never be 150 // called to allocate TLABs, only individual objects. 151 virtual HeapWord* mem_allocate(size_t size, 152 bool* gc_overhead_limit_was_exceeded) = 0; 153 154 // Filler object utilities. 155 static inline size_t filler_array_hdr_size(); 156 static inline size_t filler_array_min_size(); 157 158 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 159 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 160 161 // Fill with a single array; caller must ensure filler_array_min_size() <= 162 // words <= filler_array_max_size(). 163 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 164 165 // Fill with a single object (either an int array or a java.lang.Object). 166 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 167 168 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 169 170 // Verification functions 171 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 172 PRODUCT_RETURN; 173 debug_only(static void check_for_valid_allocation_state();) 174 175 public: 176 enum Name { 177 None, 178 Serial, 179 Parallel, 180 CMS, 181 G1, 182 Epsilon, 183 Z 184 #if INCLUDE_SHENANDOAHGC 185 ,Shenandoah 186 #endif 187 }; 188 filler_array_max_size()189 static inline size_t filler_array_max_size() { 190 return _filler_array_max_size; 191 } 192 193 virtual Name kind() const = 0; 194 195 virtual const char* name() const = 0; 196 197 /** 198 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 199 * and JNI_OK on success. 200 */ 201 virtual jint initialize() = 0; 202 203 // In many heaps, there will be a need to perform some initialization activities 204 // after the Universe is fully formed, but before general heap allocation is allowed. 205 // This is the correct place to place such initialization methods. 206 virtual void post_initialize(); 207 208 // Stop any onging concurrent work and prepare for exit. stop()209 virtual void stop() {} 210 211 // Stop and resume concurrent GC threads interfering with safepoint operations safepoint_synchronize_begin()212 virtual void safepoint_synchronize_begin() {} safepoint_synchronize_end()213 virtual void safepoint_synchronize_end() {} 214 215 void initialize_reserved_region(HeapWord *start, HeapWord *end); reserved_region() const216 MemRegion reserved_region() const { return _reserved; } base() const217 address base() const { return (address)reserved_region().start(); } 218 219 virtual size_t capacity() const = 0; 220 virtual size_t used() const = 0; 221 222 // Return "true" if the part of the heap that allocates Java 223 // objects has reached the maximal committed limit that it can 224 // reach, without a garbage collection. 225 virtual bool is_maximal_no_gc() const = 0; 226 227 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 228 // memory that the vm could make available for storing 'normal' java objects. 229 // This is based on the reserved address space, but should not include space 230 // that the vm uses internally for bookkeeping or temporary storage 231 // (e.g., in the case of the young gen, one of the survivor 232 // spaces). 233 virtual size_t max_capacity() const = 0; 234 235 // Returns "TRUE" if "p" points into the reserved area of the heap. is_in_reserved(const void * p) const236 bool is_in_reserved(const void* p) const { 237 return _reserved.contains(p); 238 } 239 is_in_reserved_or_null(const void * p) const240 bool is_in_reserved_or_null(const void* p) const { 241 return p == NULL || is_in_reserved(p); 242 } 243 244 // Returns "TRUE" iff "p" points into the committed areas of the heap. 245 // This method can be expensive so avoid using it in performance critical 246 // code. 247 virtual bool is_in(const void* p) const = 0; 248 DEBUG_ONLY(bool is_in_or_null (const void * p)const{ return p == NULL || is_in(p); })249 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 250 251 // Let's define some terms: a "closed" subset of a heap is one that 252 // 253 // 1) contains all currently-allocated objects, and 254 // 255 // 2) is closed under reference: no object in the closed subset 256 // references one outside the closed subset. 257 // 258 // Membership in a heap's closed subset is useful for assertions. 259 // Clearly, the entire heap is a closed subset, so the default 260 // implementation is to use "is_in_reserved". But this may not be too 261 // liberal to perform useful checking. Also, the "is_in" predicate 262 // defines a closed subset, but may be too expensive, since "is_in" 263 // verifies that its argument points to an object head. The 264 // "closed_subset" method allows a heap to define an intermediate 265 // predicate, allowing more precise checking than "is_in_reserved" at 266 // lower cost than "is_in." 267 268 // One important case is a heap composed of disjoint contiguous spaces, 269 // such as the Garbage-First collector. Such heaps have a convenient 270 // closed subset consisting of the allocated portions of those 271 // contiguous spaces. 272 273 // Return "TRUE" iff the given pointer points into the heap's defined 274 // closed subset (which defaults to the entire heap). 275 virtual bool is_in_closed_subset(const void* p) const { 276 return is_in_reserved(p); 277 } 278 is_in_closed_subset_or_null(const void * p) const279 bool is_in_closed_subset_or_null(const void* p) const { 280 return p == NULL || is_in_closed_subset(p); 281 } 282 set_gc_cause(GCCause::Cause v)283 void set_gc_cause(GCCause::Cause v) { 284 if (UsePerfData) { 285 _gc_lastcause = _gc_cause; 286 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 287 _perf_gc_cause->set_value(GCCause::to_string(v)); 288 } 289 _gc_cause = v; 290 } gc_cause()291 GCCause::Cause gc_cause() { return _gc_cause; } 292 293 virtual oop obj_allocate(Klass* klass, int size, TRAPS); 294 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 295 virtual oop class_allocate(Klass* klass, int size, TRAPS); 296 297 // Utilities for turning raw memory into filler objects. 298 // 299 // min_fill_size() is the smallest region that can be filled. 300 // fill_with_objects() can fill arbitrary-sized regions of the heap using 301 // multiple objects. fill_with_object() is for regions known to be smaller 302 // than the largest array of integers; it uses a single object to fill the 303 // region and has slightly less overhead. min_fill_size()304 static size_t min_fill_size() { 305 return size_t(align_object_size(oopDesc::header_size())); 306 } 307 308 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 309 310 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); fill_with_object(MemRegion region,bool zap=true)311 static void fill_with_object(MemRegion region, bool zap = true) { 312 fill_with_object(region.start(), region.word_size(), zap); 313 } fill_with_object(HeapWord * start,HeapWord * end,bool zap=true)314 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 315 fill_with_object(start, pointer_delta(end, start), zap); 316 } 317 318 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 319 320 // Return the address "addr" aligned by "alignment_in_bytes" if such 321 // an address is below "end". Return NULL otherwise. 322 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 323 HeapWord* end, 324 unsigned short alignment_in_bytes); 325 326 // Some heaps may offer a contiguous region for shared non-blocking 327 // allocation, via inlined code (by exporting the address of the top and 328 // end fields defining the extent of the contiguous allocation region.) 329 330 // This function returns "true" iff the heap supports this kind of 331 // allocation. (Default is "no".) supports_inline_contig_alloc() const332 virtual bool supports_inline_contig_alloc() const { 333 return false; 334 } 335 // These functions return the addresses of the fields that define the 336 // boundaries of the contiguous allocation area. (These fields should be 337 // physically near to one another.) top_addr() const338 virtual HeapWord* volatile* top_addr() const { 339 guarantee(false, "inline contiguous allocation not supported"); 340 return NULL; 341 } end_addr() const342 virtual HeapWord** end_addr() const { 343 guarantee(false, "inline contiguous allocation not supported"); 344 return NULL; 345 } 346 347 // Some heaps may be in an unparseable state at certain times between 348 // collections. This may be necessary for efficient implementation of 349 // certain allocation-related activities. Calling this function before 350 // attempting to parse a heap ensures that the heap is in a parsable 351 // state (provided other concurrent activity does not introduce 352 // unparsability). It is normally expected, therefore, that this 353 // method is invoked with the world stopped. 354 // NOTE: if you override this method, make sure you call 355 // super::ensure_parsability so that the non-generational 356 // part of the work gets done. See implementation of 357 // CollectedHeap::ensure_parsability and, for instance, 358 // that of GenCollectedHeap::ensure_parsability(). 359 // The argument "retire_tlabs" controls whether existing TLABs 360 // are merely filled or also retired, thus preventing further 361 // allocation from them and necessitating allocation of new TLABs. 362 virtual void ensure_parsability(bool retire_tlabs); 363 364 // Section on thread-local allocation buffers (TLABs) 365 // If the heap supports thread-local allocation buffers, it should override 366 // the following methods: 367 // Returns "true" iff the heap supports thread-local allocation buffers. 368 // The default is "no". 369 virtual bool supports_tlab_allocation() const = 0; 370 371 // The amount of space available for thread-local allocation buffers. 372 virtual size_t tlab_capacity(Thread *thr) const = 0; 373 374 // The amount of used space for thread-local allocation buffers for the given thread. 375 virtual size_t tlab_used(Thread *thr) const = 0; 376 377 virtual size_t max_tlab_size() const; 378 379 // An estimate of the maximum allocation that could be performed 380 // for thread-local allocation buffers without triggering any 381 // collection or expansion activity. unsafe_max_tlab_alloc(Thread * thr) const382 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 383 guarantee(false, "thread-local allocation buffers not supported"); 384 return 0; 385 } 386 387 // Perform a collection of the heap; intended for use in implementing 388 // "System.gc". This probably implies as full a collection as the 389 // "CollectedHeap" supports. 390 virtual void collect(GCCause::Cause cause) = 0; 391 392 // Perform a full collection 393 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 394 395 // This interface assumes that it's being called by the 396 // vm thread. It collects the heap assuming that the 397 // heap lock is already held and that we are executing in 398 // the context of the vm thread. 399 virtual void collect_as_vm_thread(GCCause::Cause cause); 400 401 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 402 size_t size, 403 Metaspace::MetadataType mdtype); 404 405 // Returns "true" iff there is a stop-world GC in progress. (I assume 406 // that it should answer "false" for the concurrent part of a concurrent 407 // collector -- dld). is_gc_active() const408 bool is_gc_active() const { return _is_gc_active; } 409 410 // Total number of GC collections (started) total_collections() const411 unsigned int total_collections() const { return _total_collections; } total_full_collections() const412 unsigned int total_full_collections() const { return _total_full_collections;} 413 414 // Increment total number of GC collections (started) 415 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 increment_total_collections(bool full=false)416 void increment_total_collections(bool full = false) { 417 _total_collections++; 418 if (full) { 419 increment_total_full_collections(); 420 } 421 } 422 increment_total_full_collections()423 void increment_total_full_collections() { _total_full_collections++; } 424 425 // Return the CollectorPolicy for the heap 426 virtual CollectorPolicy* collector_policy() const = 0; 427 428 // Return the SoftRefPolicy for the heap; 429 virtual SoftRefPolicy* soft_ref_policy() = 0; 430 431 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 432 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 433 434 // Iterate over all objects, calling "cl.do_object" on each. 435 virtual void object_iterate(ObjectClosure* cl) = 0; 436 437 // Similar to object_iterate() except iterates only 438 // over live objects. 439 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 440 441 // NOTE! There is no requirement that a collector implement these 442 // functions. 443 // 444 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 445 // each address in the (reserved) heap is a member of exactly 446 // one block. The defining characteristic of a block is that it is 447 // possible to find its size, and thus to progress forward to the next 448 // block. (Blocks may be of different sizes.) Thus, blocks may 449 // represent Java objects, or they might be free blocks in a 450 // free-list-based heap (or subheap), as long as the two kinds are 451 // distinguishable and the size of each is determinable. 452 453 // Returns the address of the start of the "block" that contains the 454 // address "addr". We say "blocks" instead of "object" since some heaps 455 // may not pack objects densely; a chunk may either be an object or a 456 // non-object. 457 virtual HeapWord* block_start(const void* addr) const = 0; 458 459 // Requires "addr" to be the start of a chunk, and returns its size. 460 // "addr + size" is required to be the start of a new chunk, or the end 461 // of the active area of the heap. 462 virtual size_t block_size(const HeapWord* addr) const = 0; 463 464 // Requires "addr" to be the start of a block, and returns "TRUE" iff 465 // the block is an object. 466 virtual bool block_is_obj(const HeapWord* addr) const = 0; 467 468 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. keep_alive(oop obj)469 virtual void keep_alive(oop obj) {} 470 471 // Returns the longest time (in ms) that has elapsed since the last 472 // time that any part of the heap was examined by a garbage collection. 473 virtual jlong millis_since_last_gc() = 0; 474 475 // Perform any cleanup actions necessary before allowing a verification. 476 virtual void prepare_for_verify() = 0; 477 478 // Generate any dumps preceding or following a full gc 479 private: 480 void full_gc_dump(GCTimer* timer, bool before); 481 482 virtual void initialize_serviceability() = 0; 483 484 public: 485 void pre_full_gc_dump(GCTimer* timer); 486 void post_full_gc_dump(GCTimer* timer); 487 488 virtual VirtualSpaceSummary create_heap_space_summary(); 489 GCHeapSummary create_heap_summary(); 490 491 MetaspaceSummary create_metaspace_summary(); 492 493 // Print heap information on the given outputStream. 494 virtual void print_on(outputStream* st) const = 0; 495 // The default behavior is to call print_on() on tty. print() const496 virtual void print() const { 497 print_on(tty); 498 } 499 // Print more detailed heap information on the given 500 // outputStream. The default behavior is to call print_on(). It is 501 // up to each subclass to override it and add any additional output 502 // it needs. print_extended_on(outputStream * st) const503 virtual void print_extended_on(outputStream* st) const { 504 print_on(st); 505 } 506 507 virtual void print_on_error(outputStream* st) const; 508 509 // Print all GC threads (other than the VM thread) 510 // used by this heap. 511 virtual void print_gc_threads_on(outputStream* st) const = 0; 512 // The default behavior is to call print_gc_threads_on() on tty. print_gc_threads()513 void print_gc_threads() { 514 print_gc_threads_on(tty); 515 } 516 // Iterator for all GC threads (other than VM thread) 517 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 518 519 // Print any relevant tracing info that flags imply. 520 // Default implementation does nothing. 521 virtual void print_tracing_info() const = 0; 522 523 void print_heap_before_gc(); 524 void print_heap_after_gc(); 525 526 // An object is scavengable if its location may move during a scavenge. 527 // (A scavenge is a GC which is not a full GC.) 528 virtual bool is_scavengable(oop obj) = 0; 529 // Registering and unregistering an nmethod (compiled code) with the heap. 530 // Override with specific mechanism for each specialized heap type. register_nmethod(nmethod * nm)531 virtual void register_nmethod(nmethod* nm) {} unregister_nmethod(nmethod * nm)532 virtual void unregister_nmethod(nmethod* nm) {} verify_nmethod(nmethod * nmethod)533 virtual void verify_nmethod(nmethod* nmethod) {} 534 535 void trace_heap_before_gc(const GCTracer* gc_tracer); 536 void trace_heap_after_gc(const GCTracer* gc_tracer); 537 538 // Heap verification 539 virtual void verify(VerifyOption option) = 0; 540 541 // Return true if concurrent phase control (via 542 // request_concurrent_phase_control) is supported by this collector. 543 // The default implementation returns false. 544 virtual bool supports_concurrent_phase_control() const; 545 546 // Return a NULL terminated array of concurrent phase names provided 547 // by this collector. Supports Whitebox testing. These are the 548 // names recognized by request_concurrent_phase(). The default 549 // implementation returns an array of one NULL element. 550 virtual const char* const* concurrent_phases() const; 551 552 // Request the collector enter the indicated concurrent phase, and 553 // wait until it does so. Supports WhiteBox testing. Only one 554 // request may be active at a time. Phases are designated by name; 555 // the set of names and their meaning is GC-specific. Once the 556 // requested phase has been reached, the collector will attempt to 557 // avoid transitioning to a new phase until a new request is made. 558 // [Note: A collector might not be able to remain in a given phase. 559 // For example, a full collection might cancel an in-progress 560 // concurrent collection.] 561 // 562 // Returns true when the phase is reached. Returns false for an 563 // unknown phase. The default implementation returns false. 564 virtual bool request_concurrent_phase(const char* phase); 565 566 // Provides a thread pool to SafepointSynchronize to use 567 // for parallel safepoint cleanup. 568 // GCs that use a GC worker thread pool may want to share 569 // it for use during safepoint cleanup. This is only possible 570 // if the GC can pause and resume concurrent work (e.g. G1 571 // concurrent marking) for an intermittent non-GC safepoint. 572 // If this method returns NULL, SafepointSynchronize will 573 // perform cleanup tasks serially in the VMThread. get_safepoint_workers()574 virtual WorkGang* get_safepoint_workers() { return NULL; } 575 576 // Support for object pinning. This is used by JNI Get*Critical() 577 // and Release*Critical() family of functions. If supported, the GC 578 // must guarantee that pinned objects never move. 579 virtual bool supports_object_pinning() const; 580 virtual oop pin_object(JavaThread* thread, oop obj); 581 virtual void unpin_object(JavaThread* thread, oop obj); 582 583 // Deduplicate the string, iff the GC supports string deduplication. 584 virtual void deduplicate_string(oop str); 585 586 virtual bool is_oop(oop object) const; 587 588 // Non product verification and debugging. 589 #ifndef PRODUCT 590 // Support for PromotionFailureALot. Return true if it's time to cause a 591 // promotion failure. The no-argument version uses 592 // this->_promotion_failure_alot_count as the counter. 593 bool promotion_should_fail(volatile size_t* count); 594 bool promotion_should_fail(); 595 596 // Reset the PromotionFailureALot counters. Should be called at the end of a 597 // GC in which promotion failure occurred. 598 void reset_promotion_should_fail(volatile size_t* count); 599 void reset_promotion_should_fail(); 600 #endif // #ifndef PRODUCT 601 602 #ifdef ASSERT fired_fake_oom()603 static int fired_fake_oom() { 604 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 605 } 606 #endif 607 }; 608 609 // Class to set and reset the GC cause for a CollectedHeap. 610 611 class GCCauseSetter : StackObj { 612 CollectedHeap* _heap; 613 GCCause::Cause _previous_cause; 614 public: GCCauseSetter(CollectedHeap * heap,GCCause::Cause cause)615 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 616 _heap = heap; 617 _previous_cause = _heap->gc_cause(); 618 _heap->set_gc_cause(cause); 619 } 620 ~GCCauseSetter()621 ~GCCauseSetter() { 622 _heap->set_gc_cause(_previous_cause); 623 } 624 }; 625 626 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP 627