1 /* 2 * Copyright (c) 2001, 2022, 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_GC_SHARED_COLLECTEDHEAP_HPP 26 #define SHARE_GC_SHARED_COLLECTEDHEAP_HPP 27 28 #include "gc/shared/gcCause.hpp" 29 #include "gc/shared/gcWhen.hpp" 30 #include "gc/shared/verifyOption.hpp" 31 #include "memory/allocation.hpp" 32 #include "memory/metaspace.hpp" 33 #include "memory/universe.hpp" 34 #include "runtime/handles.hpp" 35 #include "runtime/perfDataTypes.hpp" 36 #include "runtime/safepoint.hpp" 37 #include "services/memoryUsage.hpp" 38 #include "utilities/debug.hpp" 39 #include "utilities/formatBuffer.hpp" 40 #include "utilities/growableArray.hpp" 41 42 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 43 // is an abstract class: there may be many different kinds of heaps. This 44 // class defines the functions that a heap must implement, and contains 45 // infrastructure common to all heaps. 46 47 class WorkerTask; 48 class AdaptiveSizePolicy; 49 class BarrierSet; 50 class GCHeapLog; 51 class GCHeapSummary; 52 class GCTimer; 53 class GCTracer; 54 class GCMemoryManager; 55 class MemoryPool; 56 class MetaspaceSummary; 57 class ReservedHeapSpace; 58 class SoftRefPolicy; 59 class Thread; 60 class ThreadClosure; 61 class VirtualSpaceSummary; 62 class WorkerThreads; 63 class nmethod; 64 65 class ParallelObjectIteratorImpl : public CHeapObj<mtGC> { 66 public: 67 virtual ~ParallelObjectIteratorImpl() {} 68 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0; 69 }; 70 71 // User facing parallel object iterator. This is a StackObj, which ensures that 72 // the _impl is allocated and deleted in the scope of this object. This ensures 73 // the life cycle of the implementation is as required by ThreadsListHandle, 74 // which is sometimes used by the root iterators. 75 class ParallelObjectIterator : public StackObj { 76 ParallelObjectIteratorImpl* _impl; 77 78 public: 79 ParallelObjectIterator(uint thread_num); 80 ~ParallelObjectIterator(); 81 void object_iterate(ObjectClosure* cl, uint worker_id); 82 }; 83 84 // 85 // CollectedHeap 86 // GenCollectedHeap 87 // SerialHeap 88 // G1CollectedHeap 89 // ParallelScavengeHeap 90 // ShenandoahHeap 91 // ZCollectedHeap 92 // 93 class CollectedHeap : public CHeapObj<mtGC> { 94 friend class VMStructs; 95 friend class JVMCIVMStructs; 96 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 97 friend class MemAllocator; 98 friend class ParallelObjectIterator; 99 100 private: 101 GCHeapLog* _gc_heap_log; 102 103 // Historic gc information 104 size_t _capacity_at_last_gc; 105 size_t _used_at_last_gc; 106 107 protected: 108 // Not used by all GCs 109 MemRegion _reserved; 110 111 bool _is_gc_active; 112 113 // Used for filler objects (static, but initialized in ctor). 114 static size_t _filler_array_max_size; 115 116 // Last time the whole heap has been examined in support of RMI 117 // MaxObjectInspectionAge. 118 // This timestamp must be monotonically non-decreasing to avoid 119 // time-warp warnings. 120 jlong _last_whole_heap_examined_time_ns; 121 122 unsigned int _total_collections; // ... started 123 unsigned int _total_full_collections; // ... started 124 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 125 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 126 127 // Reason for current garbage collection. Should be set to 128 // a value reflecting no collection between collections. 129 GCCause::Cause _gc_cause; 130 GCCause::Cause _gc_lastcause; 131 PerfStringVariable* _perf_gc_cause; 132 PerfStringVariable* _perf_gc_lastcause; 133 134 // Constructor 135 CollectedHeap(); 136 137 // Create a new tlab. All TLAB allocations must go through this. 138 // To allow more flexible TLAB allocations min_size specifies 139 // the minimum size needed, while requested_size is the requested 140 // size based on ergonomics. The actually allocated size will be 141 // returned in actual_size. 142 virtual HeapWord* allocate_new_tlab(size_t min_size, 143 size_t requested_size, 144 size_t* actual_size); 145 146 // Reinitialize tlabs before resuming mutators. 147 virtual void resize_all_tlabs(); 148 149 // Raw memory allocation facilities 150 // The obj and array allocate methods are covers for these methods. 151 // mem_allocate() should never be 152 // called to allocate TLABs, only individual objects. 153 virtual HeapWord* mem_allocate(size_t size, 154 bool* gc_overhead_limit_was_exceeded) = 0; 155 156 // Filler object utilities. 157 static inline size_t filler_array_hdr_size(); 158 static inline size_t filler_array_min_size(); 159 160 static inline void zap_filler_array_with(HeapWord* start, size_t words, juint value); 161 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 162 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 163 164 // Fill with a single array; caller must ensure filler_array_min_size() <= 165 // words <= filler_array_max_size(). 166 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 167 168 // Fill with a single object (either an int array or a java.lang.Object). 169 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 170 171 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 172 173 // Verification functions 174 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 175 PRODUCT_RETURN; 176 debug_only(static void check_for_valid_allocation_state();) 177 178 public: 179 enum Name { 180 None, 181 Serial, 182 Parallel, 183 G1, 184 Epsilon, 185 Z, 186 Shenandoah 187 }; 188 189 protected: 190 // Get a pointer to the derived heap object. Used to implement 191 // derived class heap() functions rather than being called directly. 192 template<typename T> 193 static T* named_heap(Name kind) { 194 CollectedHeap* heap = Universe::heap(); 195 assert(heap != NULL, "Uninitialized heap"); 196 assert(kind == heap->kind(), "Heap kind %u should be %u", 197 static_cast<uint>(heap->kind()), static_cast<uint>(kind)); 198 return static_cast<T*>(heap); 199 } 200 201 public: 202 203 static inline size_t filler_array_max_size() { 204 return _filler_array_max_size; 205 } 206 207 virtual Name kind() const = 0; 208 209 virtual const char* name() const = 0; 210 211 /** 212 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 213 * and JNI_OK on success. 214 */ 215 virtual jint initialize() = 0; 216 217 // In many heaps, there will be a need to perform some initialization activities 218 // after the Universe is fully formed, but before general heap allocation is allowed. 219 // This is the correct place to place such initialization methods. 220 virtual void post_initialize(); 221 222 // Stop any onging concurrent work and prepare for exit. 223 virtual void stop() {} 224 225 // Stop and resume concurrent GC threads interfering with safepoint operations 226 virtual void safepoint_synchronize_begin() {} 227 virtual void safepoint_synchronize_end() {} 228 229 void initialize_reserved_region(const ReservedHeapSpace& rs); 230 231 virtual size_t capacity() const = 0; 232 virtual size_t used() const = 0; 233 234 // Returns unused capacity. 235 virtual size_t unused() const; 236 237 // Historic gc information 238 size_t free_at_last_gc() const { return _capacity_at_last_gc - _used_at_last_gc; } 239 size_t used_at_last_gc() const { return _used_at_last_gc; } 240 void update_capacity_and_used_at_gc(); 241 242 // Return "true" if the part of the heap that allocates Java 243 // objects has reached the maximal committed limit that it can 244 // reach, without a garbage collection. 245 virtual bool is_maximal_no_gc() const = 0; 246 247 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 248 // memory that the vm could make available for storing 'normal' java objects. 249 // This is based on the reserved address space, but should not include space 250 // that the vm uses internally for bookkeeping or temporary storage 251 // (e.g., in the case of the young gen, one of the survivor 252 // spaces). 253 virtual size_t max_capacity() const = 0; 254 255 // Returns "TRUE" iff "p" points into the committed areas of the heap. 256 // This method can be expensive so avoid using it in performance critical 257 // code. 258 virtual bool is_in(const void* p) const = 0; 259 260 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 261 262 virtual uint32_t hash_oop(oop obj) const; 263 264 void set_gc_cause(GCCause::Cause v); 265 GCCause::Cause gc_cause() { return _gc_cause; } 266 267 oop obj_allocate(Klass* klass, size_t size, TRAPS); 268 oop obj_buffer_allocate(Klass* klass, size_t size, TRAPS); // doesn't clear memory 269 virtual oop array_allocate(Klass* klass, size_t size, int length, bool do_zero, TRAPS); 270 oop class_allocate(Klass* klass, size_t size, TRAPS); 271 272 // Utilities for turning raw memory into filler objects. 273 // 274 // min_fill_size() is the smallest region that can be filled. 275 // fill_with_objects() can fill arbitrary-sized regions of the heap using 276 // multiple objects. fill_with_object() is for regions known to be smaller 277 // than the largest array of integers; it uses a single object to fill the 278 // region and has slightly less overhead. 279 static size_t min_fill_size() { 280 return size_t(align_object_size(oopDesc::header_size())); 281 } 282 283 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 284 285 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 286 static void fill_with_object(MemRegion region, bool zap = true) { 287 fill_with_object(region.start(), region.word_size(), zap); 288 } 289 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 290 fill_with_object(start, pointer_delta(end, start), zap); 291 } 292 293 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 294 static constexpr size_t min_dummy_object_size() { 295 return oopDesc::header_size(); 296 } 297 298 size_t tlab_alloc_reserve() const; 299 300 // Some heaps may offer a contiguous region for shared non-blocking 301 // allocation, via inlined code (by exporting the address of the top and 302 // end fields defining the extent of the contiguous allocation region.) 303 304 // This function returns "true" iff the heap supports this kind of 305 // allocation. (Default is "no".) 306 virtual bool supports_inline_contig_alloc() const { 307 return false; 308 } 309 // These functions return the addresses of the fields that define the 310 // boundaries of the contiguous allocation area. (These fields should be 311 // physically near to one another.) 312 virtual HeapWord* volatile* top_addr() const { 313 guarantee(false, "inline contiguous allocation not supported"); 314 return NULL; 315 } 316 virtual HeapWord** end_addr() const { 317 guarantee(false, "inline contiguous allocation not supported"); 318 return NULL; 319 } 320 321 // Some heaps may be in an unparseable state at certain times between 322 // collections. This may be necessary for efficient implementation of 323 // certain allocation-related activities. Calling this function before 324 // attempting to parse a heap ensures that the heap is in a parsable 325 // state (provided other concurrent activity does not introduce 326 // unparsability). It is normally expected, therefore, that this 327 // method is invoked with the world stopped. 328 // NOTE: if you override this method, make sure you call 329 // super::ensure_parsability so that the non-generational 330 // part of the work gets done. See implementation of 331 // CollectedHeap::ensure_parsability and, for instance, 332 // that of GenCollectedHeap::ensure_parsability(). 333 // The argument "retire_tlabs" controls whether existing TLABs 334 // are merely filled or also retired, thus preventing further 335 // allocation from them and necessitating allocation of new TLABs. 336 virtual void ensure_parsability(bool retire_tlabs); 337 338 // The amount of space available for thread-local allocation buffers. 339 virtual size_t tlab_capacity(Thread *thr) const = 0; 340 341 // The amount of used space for thread-local allocation buffers for the given thread. 342 virtual size_t tlab_used(Thread *thr) const = 0; 343 344 virtual size_t max_tlab_size() const; 345 346 // An estimate of the maximum allocation that could be performed 347 // for thread-local allocation buffers without triggering any 348 // collection or expansion activity. 349 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 350 guarantee(false, "thread-local allocation buffers not supported"); 351 return 0; 352 } 353 354 // If a GC uses a stack watermark barrier, the stack processing is lazy, concurrent, 355 // incremental and cooperative. In order for that to work well, mechanisms that stop 356 // another thread might want to ensure its roots are in a sane state. 357 virtual bool uses_stack_watermark_barrier() const { return false; } 358 359 // Perform a collection of the heap; intended for use in implementing 360 // "System.gc". This probably implies as full a collection as the 361 // "CollectedHeap" supports. 362 virtual void collect(GCCause::Cause cause) = 0; 363 364 // Perform a full collection 365 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 366 367 // This interface assumes that it's being called by the 368 // vm thread. It collects the heap assuming that the 369 // heap lock is already held and that we are executing in 370 // the context of the vm thread. 371 virtual void collect_as_vm_thread(GCCause::Cause cause); 372 373 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 374 size_t size, 375 Metaspace::MetadataType mdtype); 376 377 // Returns "true" iff there is a stop-world GC in progress. (I assume 378 // that it should answer "false" for the concurrent part of a concurrent 379 // collector -- dld). 380 bool is_gc_active() const { return _is_gc_active; } 381 382 // Total number of GC collections (started) 383 unsigned int total_collections() const { return _total_collections; } 384 unsigned int total_full_collections() const { return _total_full_collections;} 385 386 // Increment total number of GC collections (started) 387 void increment_total_collections(bool full = false) { 388 _total_collections++; 389 if (full) { 390 increment_total_full_collections(); 391 } 392 } 393 394 void increment_total_full_collections() { _total_full_collections++; } 395 396 // Return the SoftRefPolicy for the heap; 397 virtual SoftRefPolicy* soft_ref_policy() = 0; 398 399 virtual MemoryUsage memory_usage(); 400 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 401 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 402 403 // Iterate over all objects, calling "cl.do_object" on each. 404 virtual void object_iterate(ObjectClosure* cl) = 0; 405 406 protected: 407 virtual ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) { 408 return NULL; 409 } 410 411 public: 412 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 413 virtual void keep_alive(oop obj) {} 414 415 // Perform any cleanup actions necessary before allowing a verification. 416 virtual void prepare_for_verify() = 0; 417 418 // Returns the longest time (in ms) that has elapsed since the last 419 // time that the whole heap has been examined by a garbage collection. 420 jlong millis_since_last_whole_heap_examined(); 421 // GC should call this when the next whole heap analysis has completed to 422 // satisfy above requirement. 423 void record_whole_heap_examined_timestamp(); 424 425 private: 426 // Generate any dumps preceding or following a full gc 427 void full_gc_dump(GCTimer* timer, bool before); 428 429 virtual void initialize_serviceability() = 0; 430 431 public: 432 void pre_full_gc_dump(GCTimer* timer); 433 void post_full_gc_dump(GCTimer* timer); 434 435 virtual VirtualSpaceSummary create_heap_space_summary(); 436 GCHeapSummary create_heap_summary(); 437 438 MetaspaceSummary create_metaspace_summary(); 439 440 // Print heap information on the given outputStream. 441 virtual void print_on(outputStream* st) const = 0; 442 // The default behavior is to call print_on() on tty. 443 virtual void print() const; 444 445 // Print more detailed heap information on the given 446 // outputStream. The default behavior is to call print_on(). It is 447 // up to each subclass to override it and add any additional output 448 // it needs. 449 virtual void print_extended_on(outputStream* st) const { 450 print_on(st); 451 } 452 453 virtual void print_on_error(outputStream* st) const; 454 455 // Used to print information about locations in the hs_err file. 456 virtual bool print_location(outputStream* st, void* addr) const = 0; 457 458 // Iterator for all GC threads (other than VM thread) 459 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 460 461 // Print any relevant tracing info that flags imply. 462 // Default implementation does nothing. 463 virtual void print_tracing_info() const = 0; 464 465 void print_heap_before_gc(); 466 void print_heap_after_gc(); 467 468 // Registering and unregistering an nmethod (compiled code) with the heap. 469 virtual void register_nmethod(nmethod* nm) = 0; 470 virtual void unregister_nmethod(nmethod* nm) = 0; 471 // Callback for when nmethod is about to be deleted. 472 virtual void flush_nmethod(nmethod* nm) = 0; 473 virtual void verify_nmethod(nmethod* nm) = 0; 474 475 void trace_heap_before_gc(const GCTracer* gc_tracer); 476 void trace_heap_after_gc(const GCTracer* gc_tracer); 477 478 // Heap verification 479 virtual void verify(VerifyOption option) = 0; 480 481 // Return true if concurrent gc control via WhiteBox is supported by 482 // this collector. The default implementation returns false. 483 virtual bool supports_concurrent_gc_breakpoints() const; 484 485 // Workers used in non-GC safepoints for parallel safepoint cleanup. If this 486 // method returns NULL, cleanup tasks are done serially in the VMThread. See 487 // `SafepointSynchronize::do_cleanup_tasks` for details. 488 // GCs using a GC worker thread pool inside GC safepoints may opt to share 489 // that pool with non-GC safepoints, avoiding creating extraneous threads. 490 // Such sharing is safe, because GC safepoints and non-GC safepoints never 491 // overlap. For example, `G1CollectedHeap::workers()` (for GC safepoints) and 492 // `G1CollectedHeap::safepoint_workers()` (for non-GC safepoints) return the 493 // same thread-pool. 494 virtual WorkerThreads* safepoint_workers() { return NULL; } 495 496 // Support for object pinning. This is used by JNI Get*Critical() 497 // and Release*Critical() family of functions. If supported, the GC 498 // must guarantee that pinned objects never move. 499 virtual bool supports_object_pinning() const; 500 virtual oop pin_object(JavaThread* thread, oop obj); 501 virtual void unpin_object(JavaThread* thread, oop obj); 502 503 // Is the given object inside a CDS archive area? 504 virtual bool is_archived_object(oop object) const; 505 506 // Support for loading objects from CDS archive into the heap 507 // (usually as a snapshot of the old generation). 508 virtual bool can_load_archived_objects() const { return false; } 509 virtual HeapWord* allocate_loaded_archive_space(size_t size) { return NULL; } 510 virtual void complete_loaded_archive_space(MemRegion archive_space) { } 511 512 virtual bool is_oop(oop object) const; 513 // Non product verification and debugging. 514 #ifndef PRODUCT 515 // Support for PromotionFailureALot. Return true if it's time to cause a 516 // promotion failure. The no-argument version uses 517 // this->_promotion_failure_alot_count as the counter. 518 bool promotion_should_fail(volatile size_t* count); 519 bool promotion_should_fail(); 520 521 // Reset the PromotionFailureALot counters. Should be called at the end of a 522 // GC in which promotion failure occurred. 523 void reset_promotion_should_fail(volatile size_t* count); 524 void reset_promotion_should_fail(); 525 #endif // #ifndef PRODUCT 526 }; 527 528 // Class to set and reset the GC cause for a CollectedHeap. 529 530 class GCCauseSetter : StackObj { 531 CollectedHeap* _heap; 532 GCCause::Cause _previous_cause; 533 public: 534 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 535 _heap = heap; 536 _previous_cause = _heap->gc_cause(); 537 _heap->set_gc_cause(cause); 538 } 539 540 ~GCCauseSetter() { 541 _heap->set_gc_cause(_previous_cause); 542 } 543 }; 544 545 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP