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 // ShenandoahHeap 92 // ParallelScavengeHeap 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, size_t size, TRAPS); 146 static HeapWord* allocate_from_tlab_slow(Klass* klass, size_t size, TRAPS); 147 148 inline static HeapWord* allocate_outside_tlab(Klass* klass, size_t size, 149 bool* gc_overhead_limit_was_exceeded, TRAPS); 150 151 // Raw memory allocation facilities 152 // The obj and array allocate methods are covers for these methods. 153 // mem_allocate() should never be 154 // called to allocate TLABs, only individual objects. 155 virtual HeapWord* mem_allocate(size_t size, 156 bool* gc_overhead_limit_was_exceeded) = 0; 157 158 // Allocate an uninitialized block of the given size, or returns NULL if 159 // this is impossible. 160 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS); 161 162 // Like allocate_init, but the block returned by a successful allocation 163 // is guaranteed initialized to zeros. 164 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS); 165 166 // Helper functions for (VM) allocation. 167 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj); 168 inline static void post_allocation_setup_no_klass_install(Klass* klass, 169 HeapWord* objPtr); 170 171 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size); 172 173 inline static void post_allocation_setup_array(Klass* klass, 174 HeapWord* obj, int length); 175 176 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size); 177 178 // Clears an allocated object. 179 inline static void init_obj(HeapWord* obj, size_t size); 180 181 // Filler object utilities. 182 static inline size_t filler_array_hdr_size(); 183 static inline size_t filler_array_min_size(); 184 185 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 186 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 187 188 // Fill with a single array; caller must ensure filler_array_min_size() <= 189 // words <= filler_array_max_size(). 190 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 191 192 // Fill with a single object (either an int array or a java.lang.Object). 193 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 194 195 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 196 197 // Verification functions 198 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 199 PRODUCT_RETURN; 200 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 201 PRODUCT_RETURN; 202 debug_only(static void check_for_valid_allocation_state();) 203 204 public: 205 enum Name { 206 None, 207 Serial, 208 Parallel, 209 CMS, 210 G1, 211 Shenandoah 212 }; 213 214 static inline size_t filler_array_max_size() { 215 return _filler_array_max_size; 216 } 217 218 virtual Name kind() const = 0; 219 220 virtual HeapWord* tlab_post_allocation_setup(HeapWord* obj); 221 222 virtual const char* name() const = 0; 223 224 /** 225 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 226 * and JNI_OK on success. 227 */ 228 virtual jint initialize() = 0; 229 230 // In many heaps, there will be a need to perform some initialization activities 231 // after the Universe is fully formed, but before general heap allocation is allowed. 232 // This is the correct place to place such initialization methods. 233 virtual void post_initialize(); 234 235 // Stop any onging concurrent work and prepare for exit. 236 virtual void stop() {} 237 238 // Stop and resume concurrent GC threads interfering with safepoint operations 239 virtual void safepoint_synchronize_begin() {} 240 virtual void safepoint_synchronize_end() {} 241 242 void initialize_reserved_region(HeapWord *start, HeapWord *end); 243 MemRegion reserved_region() const { return _reserved; } 244 address base() const { return (address)reserved_region().start(); } 245 246 virtual size_t capacity() const = 0; 247 virtual size_t used() const = 0; 248 249 // Return "true" if the part of the heap that allocates Java 250 // objects has reached the maximal committed limit that it can 251 // reach, without a garbage collection. 252 virtual bool is_maximal_no_gc() const = 0; 253 254 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 255 // memory that the vm could make available for storing 'normal' java objects. 256 // This is based on the reserved address space, but should not include space 257 // that the vm uses internally for bookkeeping or temporary storage 258 // (e.g., in the case of the young gen, one of the survivor 259 // spaces). 260 virtual size_t max_capacity() const = 0; 261 262 // Returns "TRUE" if "p" points into the reserved area of the heap. 263 bool is_in_reserved(const void* p) const { 264 return _reserved.contains(p); 265 } 266 267 bool is_in_reserved_or_null(const void* p) const { 268 return p == NULL || is_in_reserved(p); 269 } 270 271 // Returns "TRUE" iff "p" points into the committed areas of the heap. 272 // This method can be expensive so avoid using it in performance critical 273 // code. 274 virtual bool is_in(const void* p) const = 0; 275 276 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 277 278 // Let's define some terms: a "closed" subset of a heap is one that 279 // 280 // 1) contains all currently-allocated objects, and 281 // 282 // 2) is closed under reference: no object in the closed subset 283 // references one outside the closed subset. 284 // 285 // Membership in a heap's closed subset is useful for assertions. 286 // Clearly, the entire heap is a closed subset, so the default 287 // implementation is to use "is_in_reserved". But this may not be too 288 // liberal to perform useful checking. Also, the "is_in" predicate 289 // defines a closed subset, but may be too expensive, since "is_in" 290 // verifies that its argument points to an object head. The 291 // "closed_subset" method allows a heap to define an intermediate 292 // predicate, allowing more precise checking than "is_in_reserved" at 293 // lower cost than "is_in." 294 295 // One important case is a heap composed of disjoint contiguous spaces, 296 // such as the Garbage-First collector. Such heaps have a convenient 297 // closed subset consisting of the allocated portions of those 298 // contiguous spaces. 299 300 // Return "TRUE" iff the given pointer points into the heap's defined 301 // closed subset (which defaults to the entire heap). 302 virtual bool is_in_closed_subset(const void* p) const { 303 return is_in_reserved(p); 304 } 305 306 bool is_in_closed_subset_or_null(const void* p) const { 307 return p == NULL || is_in_closed_subset(p); 308 } 309 310 void set_gc_cause(GCCause::Cause v) { 311 if (UsePerfData) { 312 _gc_lastcause = _gc_cause; 313 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 314 _perf_gc_cause->set_value(GCCause::to_string(v)); 315 } 316 _gc_cause = v; 317 } 318 GCCause::Cause gc_cause() { return _gc_cause; } 319 320 // General obj/array allocation facilities. 321 inline static oop obj_allocate(Klass* klass, int size, TRAPS); 322 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS); 323 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS); 324 inline static oop class_allocate(Klass* klass, int size, TRAPS); 325 326 virtual uint oop_extra_words(); 327 328 #ifndef CC_INTERP 329 virtual void compile_prepare_oop(MacroAssembler* masm, Register obj); 330 #endif 331 332 // Raw memory allocation. This may or may not use TLAB allocations to satisfy the 333 // allocation. A GC implementation may override this function to satisfy the allocation 334 // in any way. But the default is to try a TLAB allocation, and otherwise perform 335 // mem_allocate. 336 virtual HeapWord* obj_allocate_raw(Klass* klass, size_t size, 337 bool* gc_overhead_limit_was_exceeded, TRAPS); 338 339 // Utilities for turning raw memory into filler objects. 340 // 341 // min_fill_size() is the smallest region that can be filled. 342 // fill_with_objects() can fill arbitrary-sized regions of the heap using 343 // multiple objects. fill_with_object() is for regions known to be smaller 344 // than the largest array of integers; it uses a single object to fill the 345 // region and has slightly less overhead. 346 static size_t min_fill_size() { 347 return size_t(align_object_size(oopDesc::header_size())); 348 } 349 350 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 351 352 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 353 static void fill_with_object(MemRegion region, bool zap = true) { 354 fill_with_object(region.start(), region.word_size(), zap); 355 } 356 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 357 fill_with_object(start, pointer_delta(end, start), zap); 358 } 359 360 // Return the address "addr" aligned by "alignment_in_bytes" if such 361 // an address is below "end". Return NULL otherwise. 362 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 363 HeapWord* end, 364 unsigned short alignment_in_bytes); 365 366 // Some heaps may offer a contiguous region for shared non-blocking 367 // allocation, via inlined code (by exporting the address of the top and 368 // end fields defining the extent of the contiguous allocation region.) 369 370 // This function returns "true" iff the heap supports this kind of 371 // allocation. (Default is "no".) 372 virtual bool supports_inline_contig_alloc() const { 373 return false; 374 } 375 // These functions return the addresses of the fields that define the 376 // boundaries of the contiguous allocation area. (These fields should be 377 // physically near to one another.) 378 virtual HeapWord* volatile* top_addr() const { 379 guarantee(false, "inline contiguous allocation not supported"); 380 return NULL; 381 } 382 virtual HeapWord** end_addr() const { 383 guarantee(false, "inline contiguous allocation not supported"); 384 return NULL; 385 } 386 387 // Some heaps may be in an unparseable state at certain times between 388 // collections. This may be necessary for efficient implementation of 389 // certain allocation-related activities. Calling this function before 390 // attempting to parse a heap ensures that the heap is in a parsable 391 // state (provided other concurrent activity does not introduce 392 // unparsability). It is normally expected, therefore, that this 393 // method is invoked with the world stopped. 394 // NOTE: if you override this method, make sure you call 395 // super::ensure_parsability so that the non-generational 396 // part of the work gets done. See implementation of 397 // CollectedHeap::ensure_parsability and, for instance, 398 // that of GenCollectedHeap::ensure_parsability(). 399 // The argument "retire_tlabs" controls whether existing TLABs 400 // are merely filled or also retired, thus preventing further 401 // allocation from them and necessitating allocation of new TLABs. 402 virtual void ensure_parsability(bool retire_tlabs); 403 404 // Section on thread-local allocation buffers (TLABs) 405 // If the heap supports thread-local allocation buffers, it should override 406 // the following methods: 407 // Returns "true" iff the heap supports thread-local allocation buffers. 408 // The default is "no". 409 virtual bool supports_tlab_allocation() const = 0; 410 411 // The amount of space available for thread-local allocation buffers. 412 virtual size_t tlab_capacity(Thread *thr) const = 0; 413 414 // The amount of used space for thread-local allocation buffers for the given thread. 415 virtual size_t tlab_used(Thread *thr) const = 0; 416 417 virtual size_t max_tlab_size() const; 418 419 // An estimate of the maximum allocation that could be performed 420 // for thread-local allocation buffers without triggering any 421 // collection or expansion activity. 422 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 423 guarantee(false, "thread-local allocation buffers not supported"); 424 return 0; 425 } 426 427 // Perform a collection of the heap; intended for use in implementing 428 // "System.gc". This probably implies as full a collection as the 429 // "CollectedHeap" supports. 430 virtual void collect(GCCause::Cause cause) = 0; 431 432 // Perform a full collection 433 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 434 435 // This interface assumes that it's being called by the 436 // vm thread. It collects the heap assuming that the 437 // heap lock is already held and that we are executing in 438 // the context of the vm thread. 439 virtual void collect_as_vm_thread(GCCause::Cause cause); 440 441 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 442 size_t size, 443 Metaspace::MetadataType mdtype); 444 445 // Returns "true" iff there is a stop-world GC in progress. (I assume 446 // that it should answer "false" for the concurrent part of a concurrent 447 // collector -- dld). 448 bool is_gc_active() const { return _is_gc_active; } 449 450 // Total number of GC collections (started) 451 unsigned int total_collections() const { return _total_collections; } 452 unsigned int total_full_collections() const { return _total_full_collections;} 453 454 // Increment total number of GC collections (started) 455 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 456 void increment_total_collections(bool full = false) { 457 _total_collections++; 458 if (full) { 459 increment_total_full_collections(); 460 } 461 } 462 463 void increment_total_full_collections() { _total_full_collections++; } 464 465 // Return the CollectorPolicy for the heap 466 virtual CollectorPolicy* collector_policy() const = 0; 467 468 // Return the SoftRefPolicy for the heap; 469 virtual SoftRefPolicy* soft_ref_policy() = 0; 470 471 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 472 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 473 474 // Iterate over all objects, calling "cl.do_object" on each. 475 virtual void object_iterate(ObjectClosure* cl) = 0; 476 477 // Similar to object_iterate() except iterates only 478 // over live objects. 479 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 480 481 // NOTE! There is no requirement that a collector implement these 482 // functions. 483 // 484 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 485 // each address in the (reserved) heap is a member of exactly 486 // one block. The defining characteristic of a block is that it is 487 // possible to find its size, and thus to progress forward to the next 488 // block. (Blocks may be of different sizes.) Thus, blocks may 489 // represent Java objects, or they might be free blocks in a 490 // free-list-based heap (or subheap), as long as the two kinds are 491 // distinguishable and the size of each is determinable. 492 493 // Returns the address of the start of the "block" that contains the 494 // address "addr". We say "blocks" instead of "object" since some heaps 495 // may not pack objects densely; a chunk may either be an object or a 496 // non-object. 497 virtual HeapWord* block_start(const void* addr) const = 0; 498 499 // Requires "addr" to be the start of a chunk, and returns its size. 500 // "addr + size" is required to be the start of a new chunk, or the end 501 // of the active area of the heap. 502 virtual size_t block_size(const HeapWord* addr) const = 0; 503 504 // Requires "addr" to be the start of a block, and returns "TRUE" iff 505 // the block is an object. 506 virtual bool block_is_obj(const HeapWord* addr) const = 0; 507 508 // Returns the longest time (in ms) that has elapsed since the last 509 // time that any part of the heap was examined by a garbage collection. 510 virtual jlong millis_since_last_gc() = 0; 511 512 // Perform any cleanup actions necessary before allowing a verification. 513 virtual void prepare_for_verify() = 0; 514 515 // Generate any dumps preceding or following a full gc 516 private: 517 void full_gc_dump(GCTimer* timer, bool before); 518 519 virtual void initialize_serviceability() = 0; 520 521 public: 522 void pre_full_gc_dump(GCTimer* timer); 523 void post_full_gc_dump(GCTimer* timer); 524 525 virtual VirtualSpaceSummary create_heap_space_summary(); 526 GCHeapSummary create_heap_summary(); 527 528 MetaspaceSummary create_metaspace_summary(); 529 530 // Print heap information on the given outputStream. 531 virtual void print_on(outputStream* st) const = 0; 532 // The default behavior is to call print_on() on tty. 533 virtual void print() const { 534 print_on(tty); 535 } 536 // Print more detailed heap information on the given 537 // outputStream. The default behavior is to call print_on(). It is 538 // up to each subclass to override it and add any additional output 539 // it needs. 540 virtual void print_extended_on(outputStream* st) const { 541 print_on(st); 542 } 543 544 virtual void print_on_error(outputStream* st) const; 545 546 // Print all GC threads (other than the VM thread) 547 // used by this heap. 548 virtual void print_gc_threads_on(outputStream* st) const = 0; 549 // The default behavior is to call print_gc_threads_on() on tty. 550 void print_gc_threads() { 551 print_gc_threads_on(tty); 552 } 553 // Iterator for all GC threads (other than VM thread) 554 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 555 556 // Print any relevant tracing info that flags imply. 557 // Default implementation does nothing. 558 virtual void print_tracing_info() const = 0; 559 560 void print_heap_before_gc(); 561 void print_heap_after_gc(); 562 563 // An object is scavengable if its location may move during a scavenge. 564 // (A scavenge is a GC which is not a full GC.) 565 virtual bool is_scavengable(oop obj) = 0; 566 // Registering and unregistering an nmethod (compiled code) with the heap. 567 // Override with specific mechanism for each specialized heap type. 568 virtual void register_nmethod(nmethod* nm) {} 569 virtual void unregister_nmethod(nmethod* nm) {} 570 virtual void verify_nmethod(nmethod* nmethod) {} 571 572 void trace_heap_before_gc(const GCTracer* gc_tracer); 573 void trace_heap_after_gc(const GCTracer* gc_tracer); 574 575 // Heap verification 576 virtual void verify(VerifyOption option) = 0; 577 578 // Return true if concurrent phase control (via 579 // request_concurrent_phase_control) is supported by this collector. 580 // The default implementation returns false. 581 virtual bool supports_concurrent_phase_control() const; 582 583 // Return a NULL terminated array of concurrent phase names provided 584 // by this collector. Supports Whitebox testing. These are the 585 // names recognized by request_concurrent_phase(). The default 586 // implementation returns an array of one NULL element. 587 virtual const char* const* concurrent_phases() const; 588 589 // Request the collector enter the indicated concurrent phase, and 590 // wait until it does so. Supports WhiteBox testing. Only one 591 // request may be active at a time. Phases are designated by name; 592 // the set of names and their meaning is GC-specific. Once the 593 // requested phase has been reached, the collector will attempt to 594 // avoid transitioning to a new phase until a new request is made. 595 // [Note: A collector might not be able to remain in a given phase. 596 // For example, a full collection might cancel an in-progress 597 // concurrent collection.] 598 // 599 // Returns true when the phase is reached. Returns false for an 600 // unknown phase. The default implementation returns false. 601 virtual bool request_concurrent_phase(const char* phase); 602 603 // Provides a thread pool to SafepointSynchronize to use 604 // for parallel safepoint cleanup. 605 // GCs that use a GC worker thread pool may want to share 606 // it for use during safepoint cleanup. This is only possible 607 // if the GC can pause and resume concurrent work (e.g. G1 608 // concurrent marking) for an intermittent non-GC safepoint. 609 // If this method returns NULL, SafepointSynchronize will 610 // perform cleanup tasks serially in the VMThread. 611 virtual WorkGang* get_safepoint_workers() { return NULL; } 612 613 // Support for object pinning. This is used by JNI Get*Critical() 614 // and Release*Critical() family of functions. If supported, the GC 615 // must guarantee that pinned objects never move. 616 virtual bool supports_object_pinning() const; 617 virtual oop pin_object(JavaThread* thread, oop obj); 618 virtual void unpin_object(JavaThread* thread, oop obj); 619 620 // Deduplicate the string, iff the GC supports string deduplication. 621 virtual void deduplicate_string(oop str); 622 623 virtual bool is_oop(oop object) const; 624 625 // Non product verification and debugging. 626 #ifndef PRODUCT 627 // Support for PromotionFailureALot. Return true if it's time to cause a 628 // promotion failure. The no-argument version uses 629 // this->_promotion_failure_alot_count as the counter. 630 bool promotion_should_fail(volatile size_t* count); 631 bool promotion_should_fail(); 632 633 // Reset the PromotionFailureALot counters. Should be called at the end of a 634 // GC in which promotion failure occurred. 635 void reset_promotion_should_fail(volatile size_t* count); 636 void reset_promotion_should_fail(); 637 #endif // #ifndef PRODUCT 638 639 #ifdef ASSERT 640 static int fired_fake_oom() { 641 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 642 } 643 #endif 644 }; 645 646 // Class to set and reset the GC cause for a CollectedHeap. 647 648 class GCCauseSetter : StackObj { 649 CollectedHeap* _heap; 650 GCCause::Cause _previous_cause; 651 public: 652 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 653 _heap = heap; 654 _previous_cause = _heap->gc_cause(); 655 _heap->set_gc_cause(cause); 656 } 657 658 ~GCCauseSetter() { 659 _heap->set_gc_cause(_previous_cause); 660 } 661 }; 662 663 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP