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 // ZCollectedHeap 93 // 94 class CollectedHeap : public CHeapObj<mtInternal> { 95 friend class VMStructs; 96 friend class JVMCIVMStructs; 97 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 98 99 private: 100 #ifdef ASSERT 101 static int _fire_out_of_memory_count; 102 #endif 103 104 GCHeapLog* _gc_heap_log; 105 106 MemRegion _reserved; 107 108 protected: 109 bool _is_gc_active; 110 111 // Used for filler objects (static, but initialized in ctor). 112 static size_t _filler_array_max_size; 113 114 unsigned int _total_collections; // ... started 115 unsigned int _total_full_collections; // ... started 116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 118 119 // Reason for current garbage collection. Should be set to 120 // a value reflecting no collection between collections. 121 GCCause::Cause _gc_cause; 122 GCCause::Cause _gc_lastcause; 123 PerfStringVariable* _perf_gc_cause; 124 PerfStringVariable* _perf_gc_lastcause; 125 126 // Constructor 127 CollectedHeap(); 128 129 // Create a new tlab. All TLAB allocations must go through this. 130 // To allow more flexible TLAB allocations min_size specifies 131 // the minimum size needed, while requested_size is the requested 132 // size based on ergonomics. The actually allocated size will be 133 // returned in actual_size. 134 virtual HeapWord* allocate_new_tlab(size_t min_size, 135 size_t requested_size, 136 size_t* actual_size); 137 138 // Accumulate statistics on all tlabs. 139 virtual void accumulate_statistics_all_tlabs(); 140 141 // Reinitialize tlabs before resuming mutators. 142 virtual void resize_all_tlabs(); 143 144 // Allocate from the current thread's TLAB, with broken-out slow path. 145 inline static HeapWord* allocate_from_tlab(Klass* klass, Thread* thread, size_t size); 146 static HeapWord* allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size); 147 148 // Allocate an uninitialized block of the given size, or returns NULL if 149 // this is impossible. 150 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS); 151 152 // Like allocate_init, but the block returned by a successful allocation 153 // is guaranteed initialized to zeros. 154 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS); 155 156 // Helper functions for (VM) allocation. 157 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj); 158 inline static void post_allocation_setup_no_klass_install(Klass* klass, 159 HeapWord* objPtr); 160 161 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size); 162 163 inline static void post_allocation_setup_array(Klass* klass, 164 HeapWord* obj, int length); 165 166 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size); 167 168 // Clears an allocated object. 169 inline static void init_obj(HeapWord* obj, size_t size); 170 171 // Filler object utilities. 172 static inline size_t filler_array_hdr_size(); 173 static inline size_t filler_array_min_size(); 174 175 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 176 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 177 178 // Fill with a single array; caller must ensure filler_array_min_size() <= 179 // words <= filler_array_max_size(). 180 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 181 182 // Fill with a single object (either an int array or a java.lang.Object). 183 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 184 185 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 186 187 // Verification functions 188 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 189 PRODUCT_RETURN; 190 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 191 PRODUCT_RETURN; 192 debug_only(static void check_for_valid_allocation_state();) 193 194 public: 195 enum Name { 196 None, 197 Serial, 198 Parallel, 199 CMS, 200 G1, 201 Z 202 }; 203 204 static inline size_t filler_array_max_size() { 205 return _filler_array_max_size; 206 } 207 208 virtual Name kind() const = 0; 209 210 virtual const char* name() const = 0; 211 212 /** 213 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 214 * and JNI_OK on success. 215 */ 216 virtual jint initialize() = 0; 217 218 // In many heaps, there will be a need to perform some initialization activities 219 // after the Universe is fully formed, but before general heap allocation is allowed. 220 // This is the correct place to place such initialization methods. 221 virtual void post_initialize(); 222 223 // Stop any onging concurrent work and prepare for exit. 224 virtual void stop() {} 225 226 // Stop and resume concurrent GC threads interfering with safepoint operations 227 virtual void safepoint_synchronize_begin() {} 228 virtual void safepoint_synchronize_end() {} 229 230 void initialize_reserved_region(HeapWord *start, HeapWord *end); 231 MemRegion reserved_region() const { return _reserved; } 232 address base() const { return (address)reserved_region().start(); } 233 234 virtual size_t capacity() const = 0; 235 virtual size_t used() const = 0; 236 237 // Return "true" if the part of the heap that allocates Java 238 // objects has reached the maximal committed limit that it can 239 // reach, without a garbage collection. 240 virtual bool is_maximal_no_gc() const = 0; 241 242 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 243 // memory that the vm could make available for storing 'normal' java objects. 244 // This is based on the reserved address space, but should not include space 245 // that the vm uses internally for bookkeeping or temporary storage 246 // (e.g., in the case of the young gen, one of the survivor 247 // spaces). 248 virtual size_t max_capacity() const = 0; 249 250 // Returns "TRUE" if "p" points into the reserved area of the heap. 251 bool is_in_reserved(const void* p) const { 252 return _reserved.contains(p); 253 } 254 255 bool is_in_reserved_or_null(const void* p) const { 256 return p == NULL || is_in_reserved(p); 257 } 258 259 // Returns "TRUE" iff "p" points into the committed areas of the heap. 260 // This method can be expensive so avoid using it in performance critical 261 // code. 262 virtual bool is_in(const void* p) const = 0; 263 264 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 265 266 // Let's define some terms: a "closed" subset of a heap is one that 267 // 268 // 1) contains all currently-allocated objects, and 269 // 270 // 2) is closed under reference: no object in the closed subset 271 // references one outside the closed subset. 272 // 273 // Membership in a heap's closed subset is useful for assertions. 274 // Clearly, the entire heap is a closed subset, so the default 275 // implementation is to use "is_in_reserved". But this may not be too 276 // liberal to perform useful checking. Also, the "is_in" predicate 277 // defines a closed subset, but may be too expensive, since "is_in" 278 // verifies that its argument points to an object head. The 279 // "closed_subset" method allows a heap to define an intermediate 280 // predicate, allowing more precise checking than "is_in_reserved" at 281 // lower cost than "is_in." 282 283 // One important case is a heap composed of disjoint contiguous spaces, 284 // such as the Garbage-First collector. Such heaps have a convenient 285 // closed subset consisting of the allocated portions of those 286 // contiguous spaces. 287 288 // Return "TRUE" iff the given pointer points into the heap's defined 289 // closed subset (which defaults to the entire heap). 290 virtual bool is_in_closed_subset(const void* p) const { 291 return is_in_reserved(p); 292 } 293 294 bool is_in_closed_subset_or_null(const void* p) const { 295 return p == NULL || is_in_closed_subset(p); 296 } 297 298 void set_gc_cause(GCCause::Cause v) { 299 if (UsePerfData) { 300 _gc_lastcause = _gc_cause; 301 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 302 _perf_gc_cause->set_value(GCCause::to_string(v)); 303 } 304 _gc_cause = v; 305 } 306 GCCause::Cause gc_cause() { return _gc_cause; } 307 308 // General obj/array allocation facilities. 309 inline static oop obj_allocate(Klass* klass, int size, TRAPS); 310 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS); 311 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS); 312 inline static oop class_allocate(Klass* klass, int size, TRAPS); 313 314 // Raw memory allocation facilities 315 // The obj and array allocate methods are covers for these methods. 316 // mem_allocate() should never be 317 // called to allocate TLABs, only individual objects. 318 virtual HeapWord* mem_allocate(size_t size, 319 bool* gc_overhead_limit_was_exceeded) = 0; 320 321 // Utilities for turning raw memory into filler objects. 322 // 323 // min_fill_size() is the smallest region that can be filled. 324 // fill_with_objects() can fill arbitrary-sized regions of the heap using 325 // multiple objects. fill_with_object() is for regions known to be smaller 326 // than the largest array of integers; it uses a single object to fill the 327 // region and has slightly less overhead. 328 static size_t min_fill_size() { 329 return size_t(align_object_size(oopDesc::header_size())); 330 } 331 332 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 333 334 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 335 static void fill_with_object(MemRegion region, bool zap = true) { 336 fill_with_object(region.start(), region.word_size(), zap); 337 } 338 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 339 fill_with_object(start, pointer_delta(end, start), zap); 340 } 341 342 // Return the address "addr" aligned by "alignment_in_bytes" if such 343 // an address is below "end". Return NULL otherwise. 344 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 345 HeapWord* end, 346 unsigned short alignment_in_bytes); 347 348 // Some heaps may offer a contiguous region for shared non-blocking 349 // allocation, via inlined code (by exporting the address of the top and 350 // end fields defining the extent of the contiguous allocation region.) 351 352 // This function returns "true" iff the heap supports this kind of 353 // allocation. (Default is "no".) 354 virtual bool supports_inline_contig_alloc() const { 355 return false; 356 } 357 // These functions return the addresses of the fields that define the 358 // boundaries of the contiguous allocation area. (These fields should be 359 // physically near to one another.) 360 virtual HeapWord* volatile* top_addr() const { 361 guarantee(false, "inline contiguous allocation not supported"); 362 return NULL; 363 } 364 virtual HeapWord** end_addr() const { 365 guarantee(false, "inline contiguous allocation not supported"); 366 return NULL; 367 } 368 369 // Some heaps may be in an unparseable state at certain times between 370 // collections. This may be necessary for efficient implementation of 371 // certain allocation-related activities. Calling this function before 372 // attempting to parse a heap ensures that the heap is in a parsable 373 // state (provided other concurrent activity does not introduce 374 // unparsability). It is normally expected, therefore, that this 375 // method is invoked with the world stopped. 376 // NOTE: if you override this method, make sure you call 377 // super::ensure_parsability so that the non-generational 378 // part of the work gets done. See implementation of 379 // CollectedHeap::ensure_parsability and, for instance, 380 // that of GenCollectedHeap::ensure_parsability(). 381 // The argument "retire_tlabs" controls whether existing TLABs 382 // are merely filled or also retired, thus preventing further 383 // allocation from them and necessitating allocation of new TLABs. 384 virtual void ensure_parsability(bool retire_tlabs); 385 386 // Section on thread-local allocation buffers (TLABs) 387 // If the heap supports thread-local allocation buffers, it should override 388 // the following methods: 389 // Returns "true" iff the heap supports thread-local allocation buffers. 390 // The default is "no". 391 virtual bool supports_tlab_allocation() const = 0; 392 393 // The amount of space available for thread-local allocation buffers. 394 virtual size_t tlab_capacity(Thread *thr) const = 0; 395 396 // The amount of used space for thread-local allocation buffers for the given thread. 397 virtual size_t tlab_used(Thread *thr) const = 0; 398 399 virtual size_t max_tlab_size() const; 400 401 // An estimate of the maximum allocation that could be performed 402 // for thread-local allocation buffers without triggering any 403 // collection or expansion activity. 404 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 405 guarantee(false, "thread-local allocation buffers not supported"); 406 return 0; 407 } 408 409 // Perform a collection of the heap; intended for use in implementing 410 // "System.gc". This probably implies as full a collection as the 411 // "CollectedHeap" supports. 412 virtual void collect(GCCause::Cause cause) = 0; 413 414 // Perform a full collection 415 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 416 417 // This interface assumes that it's being called by the 418 // vm thread. It collects the heap assuming that the 419 // heap lock is already held and that we are executing in 420 // the context of the vm thread. 421 virtual void collect_as_vm_thread(GCCause::Cause cause); 422 423 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 424 size_t size, 425 Metaspace::MetadataType mdtype); 426 427 // Returns "true" iff there is a stop-world GC in progress. (I assume 428 // that it should answer "false" for the concurrent part of a concurrent 429 // collector -- dld). 430 bool is_gc_active() const { return _is_gc_active; } 431 432 // Total number of GC collections (started) 433 unsigned int total_collections() const { return _total_collections; } 434 unsigned int total_full_collections() const { return _total_full_collections;} 435 436 // Increment total number of GC collections (started) 437 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 438 void increment_total_collections(bool full = false) { 439 _total_collections++; 440 if (full) { 441 increment_total_full_collections(); 442 } 443 } 444 445 void increment_total_full_collections() { _total_full_collections++; } 446 447 // Return the CollectorPolicy for the heap 448 virtual CollectorPolicy* collector_policy() const = 0; 449 450 // Return the SoftRefPolicy for the heap; 451 virtual SoftRefPolicy* soft_ref_policy() = 0; 452 453 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 454 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 455 456 // Iterate over all objects, calling "cl.do_object" on each. 457 virtual void object_iterate(ObjectClosure* cl) = 0; 458 459 // Similar to object_iterate() except iterates only 460 // over live objects. 461 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 462 463 // NOTE! There is no requirement that a collector implement these 464 // functions. 465 // 466 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 467 // each address in the (reserved) heap is a member of exactly 468 // one block. The defining characteristic of a block is that it is 469 // possible to find its size, and thus to progress forward to the next 470 // block. (Blocks may be of different sizes.) Thus, blocks may 471 // represent Java objects, or they might be free blocks in a 472 // free-list-based heap (or subheap), as long as the two kinds are 473 // distinguishable and the size of each is determinable. 474 475 // Returns the address of the start of the "block" that contains the 476 // address "addr". We say "blocks" instead of "object" since some heaps 477 // may not pack objects densely; a chunk may either be an object or a 478 // non-object. 479 virtual HeapWord* block_start(const void* addr) const = 0; 480 481 // Requires "addr" to be the start of a chunk, and returns its size. 482 // "addr + size" is required to be the start of a new chunk, or the end 483 // of the active area of the heap. 484 virtual size_t block_size(const HeapWord* addr) const = 0; 485 486 // Requires "addr" to be the start of a block, and returns "TRUE" iff 487 // the block is an object. 488 virtual bool block_is_obj(const HeapWord* addr) const = 0; 489 490 // Returns the longest time (in ms) that has elapsed since the last 491 // time that any part of the heap was examined by a garbage collection. 492 virtual jlong millis_since_last_gc() = 0; 493 494 // Perform any cleanup actions necessary before allowing a verification. 495 virtual void prepare_for_verify() = 0; 496 497 // Generate any dumps preceding or following a full gc 498 private: 499 void full_gc_dump(GCTimer* timer, bool before); 500 501 virtual void initialize_serviceability() = 0; 502 503 public: 504 void pre_full_gc_dump(GCTimer* timer); 505 void post_full_gc_dump(GCTimer* timer); 506 507 virtual VirtualSpaceSummary create_heap_space_summary(); 508 GCHeapSummary create_heap_summary(); 509 510 MetaspaceSummary create_metaspace_summary(); 511 512 // Print heap information on the given outputStream. 513 virtual void print_on(outputStream* st) const = 0; 514 // The default behavior is to call print_on() on tty. 515 virtual void print() const { 516 print_on(tty); 517 } 518 // Print more detailed heap information on the given 519 // outputStream. The default behavior is to call print_on(). It is 520 // up to each subclass to override it and add any additional output 521 // it needs. 522 virtual void print_extended_on(outputStream* st) const { 523 print_on(st); 524 } 525 526 virtual void print_on_error(outputStream* st) const; 527 528 // Print all GC threads (other than the VM thread) 529 // used by this heap. 530 virtual void print_gc_threads_on(outputStream* st) const = 0; 531 // The default behavior is to call print_gc_threads_on() on tty. 532 void print_gc_threads() { 533 print_gc_threads_on(tty); 534 } 535 // Iterator for all GC threads (other than VM thread) 536 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 537 538 // Print any relevant tracing info that flags imply. 539 // Default implementation does nothing. 540 virtual void print_tracing_info() const = 0; 541 542 void print_heap_before_gc(); 543 void print_heap_after_gc(); 544 545 // An object is scavengable if its location may move during a scavenge. 546 // (A scavenge is a GC which is not a full GC.) 547 virtual bool is_scavengable(oop obj) = 0; 548 // Registering and unregistering an nmethod (compiled code) with the heap. 549 // Override with specific mechanism for each specialized heap type. 550 virtual void register_nmethod(nmethod* nm) {} 551 virtual void unregister_nmethod(nmethod* nm) {} 552 virtual void verify_nmethod(nmethod* nmethod) {} 553 554 void trace_heap_before_gc(const GCTracer* gc_tracer); 555 void trace_heap_after_gc(const GCTracer* gc_tracer); 556 557 // Heap verification 558 virtual void verify(VerifyOption option) = 0; 559 560 // Return true if concurrent phase control (via 561 // request_concurrent_phase_control) is supported by this collector. 562 // The default implementation returns false. 563 virtual bool supports_concurrent_phase_control() const; 564 565 // Return a NULL terminated array of concurrent phase names provided 566 // by this collector. Supports Whitebox testing. These are the 567 // names recognized by request_concurrent_phase(). The default 568 // implementation returns an array of one NULL element. 569 virtual const char* const* concurrent_phases() const; 570 571 // Request the collector enter the indicated concurrent phase, and 572 // wait until it does so. Supports WhiteBox testing. Only one 573 // request may be active at a time. Phases are designated by name; 574 // the set of names and their meaning is GC-specific. Once the 575 // requested phase has been reached, the collector will attempt to 576 // avoid transitioning to a new phase until a new request is made. 577 // [Note: A collector might not be able to remain in a given phase. 578 // For example, a full collection might cancel an in-progress 579 // concurrent collection.] 580 // 581 // Returns true when the phase is reached. Returns false for an 582 // unknown phase. The default implementation returns false. 583 virtual bool request_concurrent_phase(const char* phase); 584 585 // Provides a thread pool to SafepointSynchronize to use 586 // for parallel safepoint cleanup. 587 // GCs that use a GC worker thread pool may want to share 588 // it for use during safepoint cleanup. This is only possible 589 // if the GC can pause and resume concurrent work (e.g. G1 590 // concurrent marking) for an intermittent non-GC safepoint. 591 // If this method returns NULL, SafepointSynchronize will 592 // perform cleanup tasks serially in the VMThread. 593 virtual WorkGang* get_safepoint_workers() { return NULL; } 594 595 // Support for object pinning. This is used by JNI Get*Critical() 596 // and Release*Critical() family of functions. If supported, the GC 597 // must guarantee that pinned objects never move. 598 virtual bool supports_object_pinning() const; 599 virtual oop pin_object(JavaThread* thread, oop obj); 600 virtual void unpin_object(JavaThread* thread, oop obj); 601 602 // Deduplicate the string, iff the GC supports string deduplication. 603 virtual void deduplicate_string(oop str); 604 605 virtual bool is_oop(oop object) const; 606 607 // Non product verification and debugging. 608 #ifndef PRODUCT 609 // Support for PromotionFailureALot. Return true if it's time to cause a 610 // promotion failure. The no-argument version uses 611 // this->_promotion_failure_alot_count as the counter. 612 bool promotion_should_fail(volatile size_t* count); 613 bool promotion_should_fail(); 614 615 // Reset the PromotionFailureALot counters. Should be called at the end of a 616 // GC in which promotion failure occurred. 617 void reset_promotion_should_fail(volatile size_t* count); 618 void reset_promotion_should_fail(); 619 #endif // #ifndef PRODUCT 620 621 #ifdef ASSERT 622 static int fired_fake_oom() { 623 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 624 } 625 #endif 626 }; 627 628 // Class to set and reset the GC cause for a CollectedHeap. 629 630 class GCCauseSetter : StackObj { 631 CollectedHeap* _heap; 632 GCCause::Cause _previous_cause; 633 public: 634 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 635 _heap = heap; 636 _previous_cause = _heap->gc_cause(); 637 _heap->set_gc_cause(cause); 638 } 639 640 ~GCCauseSetter() { 641 _heap->set_gc_cause(_previous_cause); 642 } 643 }; 644 645 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP