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 39 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 40 // is an abstract class: there may be many different kinds of heaps. This 41 // class defines the functions that a heap must implement, and contains 42 // infrastructure common to all heaps. 43 44 class AdaptiveSizePolicy; 45 class BarrierSet; 46 class CollectorPolicy; 47 class GCHeapSummary; 48 class GCTimer; 49 class GCTracer; 50 class GCMemoryManager; 51 class MemoryPool; 52 class MetaspaceSummary; 53 class SoftRefPolicy; 54 class Thread; 55 class ThreadClosure; 56 class VirtualSpaceSummary; 57 class WorkGang; 58 class nmethod; 59 60 class GCMessage : public FormatBuffer<1024> { 61 public: 62 bool is_before; 63 64 public: 65 GCMessage() {} 66 }; 67 68 class CollectedHeap; 69 70 class GCHeapLog : public EventLogBase<GCMessage> { 71 private: 72 void log_heap(CollectedHeap* heap, bool before); 73 74 public: 75 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {} 76 77 void log_heap_before(CollectedHeap* heap) { 78 log_heap(heap, true); 79 } 80 void log_heap_after(CollectedHeap* heap) { 81 log_heap(heap, false); 82 } 83 }; 84 85 // 86 // CollectedHeap 87 // GenCollectedHeap 88 // SerialHeap 89 // CMSHeap 90 // G1CollectedHeap 91 // ParallelScavengeHeap 92 // 93 class CollectedHeap : public CHeapObj<mtInternal> { 94 friend class VMStructs; 95 friend class JVMCIVMStructs; 96 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 97 98 private: 99 #ifdef ASSERT 100 static int _fire_out_of_memory_count; 101 #endif 102 103 GCHeapLog* _gc_heap_log; 104 105 MemRegion _reserved; 106 107 protected: 108 bool _is_gc_active; 109 110 // Used for filler objects (static, but initialized in ctor). 111 static size_t _filler_array_max_size; 112 113 unsigned int _total_collections; // ... started 114 unsigned int _total_full_collections; // ... started 115 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 117 118 // Reason for current garbage collection. Should be set to 119 // a value reflecting no collection between collections. 120 GCCause::Cause _gc_cause; 121 GCCause::Cause _gc_lastcause; 122 PerfStringVariable* _perf_gc_cause; 123 PerfStringVariable* _perf_gc_lastcause; 124 125 // Constructor 126 CollectedHeap(); 127 128 // Create a new tlab. All TLAB allocations must go through this. 129 // To allow more flexible TLAB allocations min_size specifies 130 // the minimum size needed, while requested_size is the requested 131 // size based on ergonomics. The actually allocated size will be 132 // returned in actual_size. 133 virtual HeapWord* allocate_new_tlab(size_t min_size, 134 size_t requested_size, 135 size_t* actual_size); 136 137 // Accumulate statistics on all tlabs. 138 virtual void accumulate_statistics_all_tlabs(); 139 140 // Reinitialize tlabs before resuming mutators. 141 virtual void resize_all_tlabs(); 142 143 // Allocate from the current thread's TLAB, with broken-out slow path. 144 inline static HeapWord* allocate_from_tlab(Klass* klass, Thread* thread, size_t size); 145 static HeapWord* allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size); 146 147 // Allocate an uninitialized block of the given size, or returns NULL if 148 // this is impossible. 149 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS); 150 151 // Like allocate_init, but the block returned by a successful allocation 152 // is guaranteed initialized to zeros. 153 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS); 154 155 // Helper functions for (VM) allocation. 156 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj); 157 inline static void post_allocation_setup_no_klass_install(Klass* klass, 158 HeapWord* objPtr); 159 160 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size); 161 162 inline static void post_allocation_setup_array(Klass* klass, 163 HeapWord* obj, int length); 164 165 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size); 166 167 // Clears an allocated object. 168 inline static void init_obj(HeapWord* obj, size_t size); 169 170 // Filler object utilities. 171 static inline size_t filler_array_hdr_size(); 172 static inline size_t filler_array_min_size(); 173 174 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 175 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 176 177 // Fill with a single array; caller must ensure filler_array_min_size() <= 178 // words <= filler_array_max_size(). 179 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 180 181 // Fill with a single object (either an int array or a java.lang.Object). 182 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 183 184 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 185 186 // Verification functions 187 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 188 PRODUCT_RETURN; 189 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 190 PRODUCT_RETURN; 191 debug_only(static void check_for_valid_allocation_state();) 192 193 public: 194 enum Name { 195 None, 196 Serial, 197 Parallel, 198 CMS, 199 G1 200 }; 201 202 static inline size_t filler_array_max_size() { 203 return _filler_array_max_size; 204 } 205 206 virtual Name kind() const = 0; 207 208 virtual const char* name() const = 0; 209 210 /** 211 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 212 * and JNI_OK on success. 213 */ 214 virtual jint initialize() = 0; 215 216 // In many heaps, there will be a need to perform some initialization activities 217 // after the Universe is fully formed, but before general heap allocation is allowed. 218 // This is the correct place to place such initialization methods. 219 virtual void post_initialize(); 220 221 // Stop any onging concurrent work and prepare for exit. 222 virtual void stop() {} 223 224 // Stop and resume concurrent GC threads interfering with safepoint operations 225 virtual void safepoint_synchronize_begin() {} 226 virtual void safepoint_synchronize_end() {} 227 228 void initialize_reserved_region(HeapWord *start, HeapWord *end); 229 MemRegion reserved_region() const { return _reserved; } 230 address base() const { return (address)reserved_region().start(); } 231 232 virtual size_t capacity() const = 0; 233 virtual size_t used() const = 0; 234 235 // Return "true" if the part of the heap that allocates Java 236 // objects has reached the maximal committed limit that it can 237 // reach, without a garbage collection. 238 virtual bool is_maximal_no_gc() const = 0; 239 240 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 241 // memory that the vm could make available for storing 'normal' java objects. 242 // This is based on the reserved address space, but should not include space 243 // that the vm uses internally for bookkeeping or temporary storage 244 // (e.g., in the case of the young gen, one of the survivor 245 // spaces). 246 virtual size_t max_capacity() const = 0; 247 248 // Returns "TRUE" if "p" points into the reserved area of the heap. 249 bool is_in_reserved(const void* p) const { 250 return _reserved.contains(p); 251 } 252 253 bool is_in_reserved_or_null(const void* p) const { 254 return p == NULL || is_in_reserved(p); 255 } 256 257 // Returns "TRUE" iff "p" points into the committed areas of the heap. 258 // This method can be expensive so avoid using it in performance critical 259 // code. 260 virtual bool is_in(const void* p) const = 0; 261 262 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 263 264 // Let's define some terms: a "closed" subset of a heap is one that 265 // 266 // 1) contains all currently-allocated objects, and 267 // 268 // 2) is closed under reference: no object in the closed subset 269 // references one outside the closed subset. 270 // 271 // Membership in a heap's closed subset is useful for assertions. 272 // Clearly, the entire heap is a closed subset, so the default 273 // implementation is to use "is_in_reserved". But this may not be too 274 // liberal to perform useful checking. Also, the "is_in" predicate 275 // defines a closed subset, but may be too expensive, since "is_in" 276 // verifies that its argument points to an object head. The 277 // "closed_subset" method allows a heap to define an intermediate 278 // predicate, allowing more precise checking than "is_in_reserved" at 279 // lower cost than "is_in." 280 281 // One important case is a heap composed of disjoint contiguous spaces, 282 // such as the Garbage-First collector. Such heaps have a convenient 283 // closed subset consisting of the allocated portions of those 284 // contiguous spaces. 285 286 // Return "TRUE" iff the given pointer points into the heap's defined 287 // closed subset (which defaults to the entire heap). 288 virtual bool is_in_closed_subset(const void* p) const { 289 return is_in_reserved(p); 290 } 291 292 bool is_in_closed_subset_or_null(const void* p) const { 293 return p == NULL || is_in_closed_subset(p); 294 } 295 296 void set_gc_cause(GCCause::Cause v) { 297 if (UsePerfData) { 298 _gc_lastcause = _gc_cause; 299 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 300 _perf_gc_cause->set_value(GCCause::to_string(v)); 301 } 302 _gc_cause = v; 303 } 304 GCCause::Cause gc_cause() { return _gc_cause; } 305 306 // General obj/array allocation facilities. 307 inline static oop obj_allocate(Klass* klass, int size, TRAPS); 308 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS); 309 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS); 310 inline static oop class_allocate(Klass* klass, int size, TRAPS); 311 312 // Raw memory allocation facilities 313 // The obj and array allocate methods are covers for these methods. 314 // mem_allocate() should never be 315 // called to allocate TLABs, only individual objects. 316 virtual HeapWord* mem_allocate(size_t size, 317 bool* gc_overhead_limit_was_exceeded) = 0; 318 319 // Utilities for turning raw memory into filler objects. 320 // 321 // min_fill_size() is the smallest region that can be filled. 322 // fill_with_objects() can fill arbitrary-sized regions of the heap using 323 // multiple objects. fill_with_object() is for regions known to be smaller 324 // than the largest array of integers; it uses a single object to fill the 325 // region and has slightly less overhead. 326 static size_t min_fill_size() { 327 return size_t(align_object_size(oopDesc::header_size())); 328 } 329 330 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 331 332 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 333 static void fill_with_object(MemRegion region, bool zap = true) { 334 fill_with_object(region.start(), region.word_size(), zap); 335 } 336 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 337 fill_with_object(start, pointer_delta(end, start), zap); 338 } 339 340 // Return the address "addr" aligned by "alignment_in_bytes" if such 341 // an address is below "end". Return NULL otherwise. 342 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 343 HeapWord* end, 344 unsigned short alignment_in_bytes); 345 346 // Some heaps may offer a contiguous region for shared non-blocking 347 // allocation, via inlined code (by exporting the address of the top and 348 // end fields defining the extent of the contiguous allocation region.) 349 350 // This function returns "true" iff the heap supports this kind of 351 // allocation. (Default is "no".) 352 virtual bool supports_inline_contig_alloc() const { 353 return false; 354 } 355 // These functions return the addresses of the fields that define the 356 // boundaries of the contiguous allocation area. (These fields should be 357 // physically near to one another.) 358 virtual HeapWord* volatile* top_addr() const { 359 guarantee(false, "inline contiguous allocation not supported"); 360 return NULL; 361 } 362 virtual HeapWord** end_addr() const { 363 guarantee(false, "inline contiguous allocation not supported"); 364 return NULL; 365 } 366 367 // Some heaps may be in an unparseable state at certain times between 368 // collections. This may be necessary for efficient implementation of 369 // certain allocation-related activities. Calling this function before 370 // attempting to parse a heap ensures that the heap is in a parsable 371 // state (provided other concurrent activity does not introduce 372 // unparsability). It is normally expected, therefore, that this 373 // method is invoked with the world stopped. 374 // NOTE: if you override this method, make sure you call 375 // super::ensure_parsability so that the non-generational 376 // part of the work gets done. See implementation of 377 // CollectedHeap::ensure_parsability and, for instance, 378 // that of GenCollectedHeap::ensure_parsability(). 379 // The argument "retire_tlabs" controls whether existing TLABs 380 // are merely filled or also retired, thus preventing further 381 // allocation from them and necessitating allocation of new TLABs. 382 virtual void ensure_parsability(bool retire_tlabs); 383 384 // Section on thread-local allocation buffers (TLABs) 385 // If the heap supports thread-local allocation buffers, it should override 386 // the following methods: 387 // Returns "true" iff the heap supports thread-local allocation buffers. 388 // The default is "no". 389 virtual bool supports_tlab_allocation() const = 0; 390 391 // The amount of space available for thread-local allocation buffers. 392 virtual size_t tlab_capacity(Thread *thr) const = 0; 393 394 // The amount of used space for thread-local allocation buffers for the given thread. 395 virtual size_t tlab_used(Thread *thr) const = 0; 396 397 virtual size_t max_tlab_size() const; 398 399 // An estimate of the maximum allocation that could be performed 400 // for thread-local allocation buffers without triggering any 401 // collection or expansion activity. 402 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 403 guarantee(false, "thread-local allocation buffers not supported"); 404 return 0; 405 } 406 407 // Perform a collection of the heap; intended for use in implementing 408 // "System.gc". This probably implies as full a collection as the 409 // "CollectedHeap" supports. 410 virtual void collect(GCCause::Cause cause) = 0; 411 412 // Perform a full collection 413 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 414 415 // This interface assumes that it's being called by the 416 // vm thread. It collects the heap assuming that the 417 // heap lock is already held and that we are executing in 418 // the context of the vm thread. 419 virtual void collect_as_vm_thread(GCCause::Cause cause); 420 421 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 422 size_t size, 423 Metaspace::MetadataType mdtype); 424 425 // Returns "true" iff there is a stop-world GC in progress. (I assume 426 // that it should answer "false" for the concurrent part of a concurrent 427 // collector -- dld). 428 bool is_gc_active() const { return _is_gc_active; } 429 430 // Total number of GC collections (started) 431 unsigned int total_collections() const { return _total_collections; } 432 unsigned int total_full_collections() const { return _total_full_collections;} 433 434 // Increment total number of GC collections (started) 435 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 436 void increment_total_collections(bool full = false) { 437 _total_collections++; 438 if (full) { 439 increment_total_full_collections(); 440 } 441 } 442 443 void increment_total_full_collections() { _total_full_collections++; } 444 445 // Return the CollectorPolicy for the heap 446 virtual CollectorPolicy* collector_policy() const = 0; 447 448 // Return the SoftRefPolicy for the heap; 449 virtual SoftRefPolicy* soft_ref_policy() = 0; 450 451 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 452 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 453 454 // Iterate over all objects, calling "cl.do_object" on each. 455 virtual void object_iterate(ObjectClosure* cl) = 0; 456 457 // Similar to object_iterate() except iterates only 458 // over live objects. 459 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 460 461 // NOTE! There is no requirement that a collector implement these 462 // functions. 463 // 464 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 465 // each address in the (reserved) heap is a member of exactly 466 // one block. The defining characteristic of a block is that it is 467 // possible to find its size, and thus to progress forward to the next 468 // block. (Blocks may be of different sizes.) Thus, blocks may 469 // represent Java objects, or they might be free blocks in a 470 // free-list-based heap (or subheap), as long as the two kinds are 471 // distinguishable and the size of each is determinable. 472 473 // Returns the address of the start of the "block" that contains the 474 // address "addr". We say "blocks" instead of "object" since some heaps 475 // may not pack objects densely; a chunk may either be an object or a 476 // non-object. 477 virtual HeapWord* block_start(const void* addr) const = 0; 478 479 // Requires "addr" to be the start of a chunk, and returns its size. 480 // "addr + size" is required to be the start of a new chunk, or the end 481 // of the active area of the heap. 482 virtual size_t block_size(const HeapWord* addr) const = 0; 483 484 // Requires "addr" to be the start of a block, and returns "TRUE" iff 485 // the block is an object. 486 virtual bool block_is_obj(const HeapWord* addr) const = 0; 487 488 // Returns the longest time (in ms) that has elapsed since the last 489 // time that any part of the heap was examined by a garbage collection. 490 virtual jlong millis_since_last_gc() = 0; 491 492 // Perform any cleanup actions necessary before allowing a verification. 493 virtual void prepare_for_verify() = 0; 494 495 // Generate any dumps preceding or following a full gc 496 private: 497 void full_gc_dump(GCTimer* timer, bool before); 498 499 virtual void initialize_serviceability() = 0; 500 501 public: 502 void pre_full_gc_dump(GCTimer* timer); 503 void post_full_gc_dump(GCTimer* timer); 504 505 virtual VirtualSpaceSummary create_heap_space_summary(); 506 GCHeapSummary create_heap_summary(); 507 508 MetaspaceSummary create_metaspace_summary(); 509 510 // Print heap information on the given outputStream. 511 virtual void print_on(outputStream* st) const = 0; 512 // The default behavior is to call print_on() on tty. 513 virtual void print() const { 514 print_on(tty); 515 } 516 // Print more detailed heap information on the given 517 // outputStream. The default behavior is to call print_on(). It is 518 // up to each subclass to override it and add any additional output 519 // it needs. 520 virtual void print_extended_on(outputStream* st) const { 521 print_on(st); 522 } 523 524 virtual void print_on_error(outputStream* st) const; 525 526 // Print all GC threads (other than the VM thread) 527 // used by this heap. 528 virtual void print_gc_threads_on(outputStream* st) const = 0; 529 // The default behavior is to call print_gc_threads_on() on tty. 530 void print_gc_threads() { 531 print_gc_threads_on(tty); 532 } 533 // Iterator for all GC threads (other than VM thread) 534 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 535 536 // Print any relevant tracing info that flags imply. 537 // Default implementation does nothing. 538 virtual void print_tracing_info() const = 0; 539 540 void print_heap_before_gc(); 541 void print_heap_after_gc(); 542 543 // An object is scavengable if its location may move during a scavenge. 544 // (A scavenge is a GC which is not a full GC.) 545 virtual bool is_scavengable(oop obj) = 0; 546 // Registering and unregistering an nmethod (compiled code) with the heap. 547 // Override with specific mechanism for each specialized heap type. 548 virtual void register_nmethod(nmethod* nm) {} 549 virtual void unregister_nmethod(nmethod* nm) {} 550 virtual void verify_nmethod(nmethod* nmethod) {} 551 552 void trace_heap_before_gc(const GCTracer* gc_tracer); 553 void trace_heap_after_gc(const GCTracer* gc_tracer); 554 555 // Heap verification 556 virtual void verify(VerifyOption option) = 0; 557 558 // Return true if concurrent phase control (via 559 // request_concurrent_phase_control) is supported by this collector. 560 // The default implementation returns false. 561 virtual bool supports_concurrent_phase_control() const; 562 563 // Return a NULL terminated array of concurrent phase names provided 564 // by this collector. Supports Whitebox testing. These are the 565 // names recognized by request_concurrent_phase(). The default 566 // implementation returns an array of one NULL element. 567 virtual const char* const* concurrent_phases() const; 568 569 // Request the collector enter the indicated concurrent phase, and 570 // wait until it does so. Supports WhiteBox testing. Only one 571 // request may be active at a time. Phases are designated by name; 572 // the set of names and their meaning is GC-specific. Once the 573 // requested phase has been reached, the collector will attempt to 574 // avoid transitioning to a new phase until a new request is made. 575 // [Note: A collector might not be able to remain in a given phase. 576 // For example, a full collection might cancel an in-progress 577 // concurrent collection.] 578 // 579 // Returns true when the phase is reached. Returns false for an 580 // unknown phase. The default implementation returns false. 581 virtual bool request_concurrent_phase(const char* phase); 582 583 // Provides a thread pool to SafepointSynchronize to use 584 // for parallel safepoint cleanup. 585 // GCs that use a GC worker thread pool may want to share 586 // it for use during safepoint cleanup. This is only possible 587 // if the GC can pause and resume concurrent work (e.g. G1 588 // concurrent marking) for an intermittent non-GC safepoint. 589 // If this method returns NULL, SafepointSynchronize will 590 // perform cleanup tasks serially in the VMThread. 591 virtual WorkGang* get_safepoint_workers() { return NULL; } 592 593 // Support for object pinning. This is used by JNI Get*Critical() 594 // and Release*Critical() family of functions. If supported, the GC 595 // must guarantee that pinned objects never move. 596 virtual bool supports_object_pinning() const; 597 virtual oop pin_object(JavaThread* thread, oop obj); 598 virtual void unpin_object(JavaThread* thread, oop obj); 599 600 // Deduplicate the string, iff the GC supports string deduplication. 601 virtual void deduplicate_string(oop str); 602 603 virtual bool is_oop(oop object) const; 604 605 // Non product verification and debugging. 606 #ifndef PRODUCT 607 // Support for PromotionFailureALot. Return true if it's time to cause a 608 // promotion failure. The no-argument version uses 609 // this->_promotion_failure_alot_count as the counter. 610 bool promotion_should_fail(volatile size_t* count); 611 bool promotion_should_fail(); 612 613 // Reset the PromotionFailureALot counters. Should be called at the end of a 614 // GC in which promotion failure occurred. 615 void reset_promotion_should_fail(volatile size_t* count); 616 void reset_promotion_should_fail(); 617 #endif // #ifndef PRODUCT 618 619 #ifdef ASSERT 620 static int fired_fake_oom() { 621 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 622 } 623 #endif 624 }; 625 626 // Class to set and reset the GC cause for a CollectedHeap. 627 628 class GCCauseSetter : StackObj { 629 CollectedHeap* _heap; 630 GCCause::Cause _previous_cause; 631 public: 632 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 633 _heap = heap; 634 _previous_cause = _heap->gc_cause(); 635 _heap->set_gc_cause(cause); 636 } 637 638 ~GCCauseSetter() { 639 _heap->set_gc_cause(_previous_cause); 640 } 641 }; 642 643 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP