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