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