1 /* 2 * Copyright (c) 2001, 2020, 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/heapInspection.hpp" 33 #include "memory/universe.hpp" 34 #include "runtime/handles.hpp" 35 #include "runtime/perfData.hpp" 36 #include "runtime/safepoint.hpp" 37 #include "services/memoryUsage.hpp" 38 #include "utilities/debug.hpp" 39 #include "utilities/events.hpp" 40 #include "utilities/formatBuffer.hpp" 41 #include "utilities/growableArray.hpp" 42 43 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 44 // is an abstract class: there may be many different kinds of heaps. This 45 // class defines the functions that a heap must implement, and contains 46 // infrastructure common to all heaps. 47 48 class AbstractGangTask; 49 class AdaptiveSizePolicy; 50 class BarrierSet; 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 WorkGang; 63 class nmethod; 64 65 class GCMessage : public FormatBuffer<1024> { 66 public: 67 bool is_before; 68 69 public: 70 GCMessage() {} 71 }; 72 73 class CollectedHeap; 74 75 class GCHeapLog : public EventLogBase<GCMessage> { 76 private: 77 void log_heap(CollectedHeap* heap, bool before); 78 79 public: 80 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {} 81 82 void log_heap_before(CollectedHeap* heap) { 83 log_heap(heap, true); 84 } 85 void log_heap_after(CollectedHeap* heap) { 86 log_heap(heap, false); 87 } 88 }; 89 90 class ParallelObjectIterator : public CHeapObj<mtGC> { 91 public: 92 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0; 93 }; 94 95 // 96 // CollectedHeap 97 // GenCollectedHeap 98 // SerialHeap 99 // G1CollectedHeap 100 // ParallelScavengeHeap 101 // ShenandoahHeap 102 // ZCollectedHeap 103 // 104 class CollectedHeap : public CHeapObj<mtInternal> { 105 friend class VMStructs; 106 friend class JVMCIVMStructs; 107 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 108 friend class MemAllocator; 109 110 private: 111 GCHeapLog* _gc_heap_log; 112 113 protected: 114 // Not used by all GCs 115 MemRegion _reserved; 116 117 bool _is_gc_active; 118 119 // Used for filler objects (static, but initialized in ctor). 120 static size_t _filler_array_max_size; 121 122 // Last time the whole heap has been examined in support of RMI 123 // MaxObjectInspectionAge. 124 // This timestamp must be monotonically non-decreasing to avoid 125 // time-warp warnings. 126 jlong _last_whole_heap_examined_time_ns; 127 128 unsigned int _total_collections; // ... started 129 unsigned int _total_full_collections; // ... started 130 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 131 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 132 133 // Reason for current garbage collection. Should be set to 134 // a value reflecting no collection between collections. 135 GCCause::Cause _gc_cause; 136 GCCause::Cause _gc_lastcause; 137 PerfStringVariable* _perf_gc_cause; 138 PerfStringVariable* _perf_gc_lastcause; 139 140 // Constructor 141 CollectedHeap(); 142 143 // Create a new tlab. All TLAB allocations must go through this. 144 // To allow more flexible TLAB allocations min_size specifies 145 // the minimum size needed, while requested_size is the requested 146 // size based on ergonomics. The actually allocated size will be 147 // returned in actual_size. 148 virtual HeapWord* allocate_new_tlab(size_t min_size, 149 size_t requested_size, 150 size_t* actual_size); 151 152 // Reinitialize tlabs before resuming mutators. 153 virtual void resize_all_tlabs(); 154 155 // Raw memory allocation facilities 156 // The obj and array allocate methods are covers for these methods. 157 // mem_allocate() should never be 158 // called to allocate TLABs, only individual objects. 159 virtual HeapWord* mem_allocate(size_t size, 160 bool* gc_overhead_limit_was_exceeded) = 0; 161 162 // Filler object utilities. 163 static inline size_t filler_array_hdr_size(); 164 static inline size_t filler_array_min_size(); 165 166 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 167 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 168 169 // Fill with a single array; caller must ensure filler_array_min_size() <= 170 // words <= filler_array_max_size(). 171 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 172 173 // Fill with a single object (either an int array or a java.lang.Object). 174 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 175 176 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 177 178 // Verification functions 179 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 180 PRODUCT_RETURN; 181 debug_only(static void check_for_valid_allocation_state();) 182 183 public: 184 enum Name { 185 None, 186 Serial, 187 Parallel, 188 G1, 189 Epsilon, 190 Z, 191 Shenandoah 192 }; 193 194 protected: 195 // Get a pointer to the derived heap object. Used to implement 196 // derived class heap() functions rather than being called directly. 197 template<typename T> 198 static T* named_heap(Name kind) { 199 CollectedHeap* heap = Universe::heap(); 200 assert(heap != NULL, "Uninitialized heap"); 201 assert(kind == heap->kind(), "Heap kind %u should be %u", 202 static_cast<uint>(heap->kind()), static_cast<uint>(kind)); 203 return static_cast<T*>(heap); 204 } 205 206 public: 207 208 static inline size_t filler_array_max_size() { 209 return _filler_array_max_size; 210 } 211 212 virtual Name kind() const = 0; 213 214 virtual const char* name() const = 0; 215 216 /** 217 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 218 * and JNI_OK on success. 219 */ 220 virtual jint initialize() = 0; 221 222 // In many heaps, there will be a need to perform some initialization activities 223 // after the Universe is fully formed, but before general heap allocation is allowed. 224 // This is the correct place to place such initialization methods. 225 virtual void post_initialize(); 226 227 // Stop any onging concurrent work and prepare for exit. 228 virtual void stop() {} 229 230 // Stop and resume concurrent GC threads interfering with safepoint operations 231 virtual void safepoint_synchronize_begin() {} 232 virtual void safepoint_synchronize_end() {} 233 234 void initialize_reserved_region(const ReservedHeapSpace& rs); 235 236 virtual size_t capacity() const = 0; 237 virtual size_t used() const = 0; 238 239 // Returns unused capacity. 240 virtual size_t unused() const; 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 if (UsePerfData) { 266 _gc_lastcause = _gc_cause; 267 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 268 _perf_gc_cause->set_value(GCCause::to_string(v)); 269 } 270 _gc_cause = v; 271 } 272 GCCause::Cause gc_cause() { return _gc_cause; } 273 274 oop obj_allocate(Klass* klass, int size, TRAPS); 275 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 276 oop class_allocate(Klass* klass, int size, TRAPS); 277 278 // Utilities for turning raw memory into filler objects. 279 // 280 // min_fill_size() is the smallest region that can be filled. 281 // fill_with_objects() can fill arbitrary-sized regions of the heap using 282 // multiple objects. fill_with_object() is for regions known to be smaller 283 // than the largest array of integers; it uses a single object to fill the 284 // region and has slightly less overhead. 285 static size_t min_fill_size() { 286 return size_t(align_object_size(oopDesc::header_size())); 287 } 288 289 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 290 291 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 292 static void fill_with_object(MemRegion region, bool zap = true) { 293 fill_with_object(region.start(), region.word_size(), zap); 294 } 295 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 296 fill_with_object(start, pointer_delta(end, start), zap); 297 } 298 299 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 300 virtual size_t min_dummy_object_size() const; 301 size_t tlab_alloc_reserve() const; 302 303 // Return the address "addr" aligned by "alignment_in_bytes" if such 304 // an address is below "end". Return NULL otherwise. 305 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 306 HeapWord* end, 307 unsigned short alignment_in_bytes); 308 309 // Some heaps may offer a contiguous region for shared non-blocking 310 // allocation, via inlined code (by exporting the address of the top and 311 // end fields defining the extent of the contiguous allocation region.) 312 313 // This function returns "true" iff the heap supports this kind of 314 // allocation. (Default is "no".) 315 virtual bool supports_inline_contig_alloc() const { 316 return false; 317 } 318 // These functions return the addresses of the fields that define the 319 // boundaries of the contiguous allocation area. (These fields should be 320 // physically near to one another.) 321 virtual HeapWord* volatile* top_addr() const { 322 guarantee(false, "inline contiguous allocation not supported"); 323 return NULL; 324 } 325 virtual HeapWord** end_addr() const { 326 guarantee(false, "inline contiguous allocation not supported"); 327 return NULL; 328 } 329 330 // Some heaps may be in an unparseable state at certain times between 331 // collections. This may be necessary for efficient implementation of 332 // certain allocation-related activities. Calling this function before 333 // attempting to parse a heap ensures that the heap is in a parsable 334 // state (provided other concurrent activity does not introduce 335 // unparsability). It is normally expected, therefore, that this 336 // method is invoked with the world stopped. 337 // NOTE: if you override this method, make sure you call 338 // super::ensure_parsability so that the non-generational 339 // part of the work gets done. See implementation of 340 // CollectedHeap::ensure_parsability and, for instance, 341 // that of GenCollectedHeap::ensure_parsability(). 342 // The argument "retire_tlabs" controls whether existing TLABs 343 // are merely filled or also retired, thus preventing further 344 // allocation from them and necessitating allocation of new TLABs. 345 virtual void ensure_parsability(bool retire_tlabs); 346 347 // Section on thread-local allocation buffers (TLABs) 348 // If the heap supports thread-local allocation buffers, it should override 349 // the following methods: 350 // Returns "true" iff the heap supports thread-local allocation buffers. 351 // The default is "no". 352 virtual bool supports_tlab_allocation() const = 0; 353 354 // The amount of space available for thread-local allocation buffers. 355 virtual size_t tlab_capacity(Thread *thr) const = 0; 356 357 // The amount of used space for thread-local allocation buffers for the given thread. 358 virtual size_t tlab_used(Thread *thr) const = 0; 359 360 virtual size_t max_tlab_size() const; 361 362 // An estimate of the maximum allocation that could be performed 363 // for thread-local allocation buffers without triggering any 364 // collection or expansion activity. 365 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 366 guarantee(false, "thread-local allocation buffers not supported"); 367 return 0; 368 } 369 370 // Perform a collection of the heap; intended for use in implementing 371 // "System.gc". This probably implies as full a collection as the 372 // "CollectedHeap" supports. 373 virtual void collect(GCCause::Cause cause) = 0; 374 375 // Perform a full collection 376 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 377 378 // This interface assumes that it's being called by the 379 // vm thread. It collects the heap assuming that the 380 // heap lock is already held and that we are executing in 381 // the context of the vm thread. 382 virtual void collect_as_vm_thread(GCCause::Cause cause); 383 384 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 385 size_t size, 386 Metaspace::MetadataType mdtype); 387 388 // Returns "true" iff there is a stop-world GC in progress. (I assume 389 // that it should answer "false" for the concurrent part of a concurrent 390 // collector -- dld). 391 bool is_gc_active() const { return _is_gc_active; } 392 393 // Total number of GC collections (started) 394 unsigned int total_collections() const { return _total_collections; } 395 unsigned int total_full_collections() const { return _total_full_collections;} 396 397 // Increment total number of GC collections (started) 398 void increment_total_collections(bool full = false) { 399 _total_collections++; 400 if (full) { 401 increment_total_full_collections(); 402 } 403 } 404 405 void increment_total_full_collections() { _total_full_collections++; } 406 407 // Return the SoftRefPolicy for the heap; 408 virtual SoftRefPolicy* soft_ref_policy() = 0; 409 410 virtual MemoryUsage memory_usage(); 411 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 412 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 413 414 // Iterate over all objects, calling "cl.do_object" on each. 415 virtual void object_iterate(ObjectClosure* cl) = 0; 416 417 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num) { 418 return NULL; 419 } 420 421 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 422 virtual void keep_alive(oop obj) {} 423 424 // Perform any cleanup actions necessary before allowing a verification. 425 virtual void prepare_for_verify() = 0; 426 427 // Returns the longest time (in ms) that has elapsed since the last 428 // time that the whole heap has been examined by a garbage collection. 429 jlong millis_since_last_whole_heap_examined(); 430 // GC should call this when the next whole heap analysis has completed to 431 // satisfy above requirement. 432 void record_whole_heap_examined_timestamp(); 433 434 private: 435 // Generate any dumps preceding or following a full gc 436 void full_gc_dump(GCTimer* timer, bool before); 437 438 virtual void initialize_serviceability() = 0; 439 440 public: 441 void pre_full_gc_dump(GCTimer* timer); 442 void post_full_gc_dump(GCTimer* timer); 443 444 virtual VirtualSpaceSummary create_heap_space_summary(); 445 GCHeapSummary create_heap_summary(); 446 447 MetaspaceSummary create_metaspace_summary(); 448 449 // Print heap information on the given outputStream. 450 virtual void print_on(outputStream* st) const = 0; 451 // The default behavior is to call print_on() on tty. 452 virtual void print() const; 453 454 // Print more detailed heap information on the given 455 // outputStream. The default behavior is to call print_on(). It is 456 // up to each subclass to override it and add any additional output 457 // it needs. 458 virtual void print_extended_on(outputStream* st) const { 459 print_on(st); 460 } 461 462 virtual void print_on_error(outputStream* st) const; 463 464 // Used to print information about locations in the hs_err file. 465 virtual bool print_location(outputStream* st, void* addr) const = 0; 466 467 // Iterator for all GC threads (other than VM thread) 468 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 469 470 // Runs the given task with (up to) the requested number of workers. 471 // Some GCs don't support parallel worker threads and will run the 472 // task in one thread, with worker id 0. 473 void run_task_at_safepoint(AbstractGangTask* task, uint num_workers); 474 475 // Print any relevant tracing info that flags imply. 476 // Default implementation does nothing. 477 virtual void print_tracing_info() const = 0; 478 479 void print_heap_before_gc(); 480 void print_heap_after_gc(); 481 482 // Registering and unregistering an nmethod (compiled code) with the heap. 483 virtual void register_nmethod(nmethod* nm) = 0; 484 virtual void unregister_nmethod(nmethod* nm) = 0; 485 // Callback for when nmethod is about to be deleted. 486 virtual void flush_nmethod(nmethod* nm) = 0; 487 virtual void verify_nmethod(nmethod* nm) = 0; 488 489 void trace_heap_before_gc(const GCTracer* gc_tracer); 490 void trace_heap_after_gc(const GCTracer* gc_tracer); 491 492 // Heap verification 493 virtual void verify(VerifyOption option) = 0; 494 495 // Return true if concurrent gc control via WhiteBox is supported by 496 // this collector. The default implementation returns false. 497 virtual bool supports_concurrent_gc_breakpoints() const; 498 499 // Provides a thread pool to SafepointSynchronize to use 500 // for parallel safepoint cleanup. 501 // GCs that use a GC worker thread pool may want to share 502 // it for use during safepoint cleanup. This is only possible 503 // if the GC can pause and resume concurrent work (e.g. G1 504 // concurrent marking) for an intermittent non-GC safepoint. 505 // If this method returns NULL, SafepointSynchronize will 506 // perform cleanup tasks serially in the VMThread. 507 virtual WorkGang* get_safepoint_workers() { return NULL; } 508 509 // Support for object pinning. This is used by JNI Get*Critical() 510 // and Release*Critical() family of functions. If supported, the GC 511 // must guarantee that pinned objects never move. 512 virtual bool supports_object_pinning() const; 513 virtual oop pin_object(JavaThread* thread, oop obj); 514 virtual void unpin_object(JavaThread* thread, oop obj); 515 516 // Deduplicate the string, iff the GC supports string deduplication. 517 virtual void deduplicate_string(oop str); 518 519 virtual bool is_oop(oop object) const; 520 521 // Non product verification and debugging. 522 #ifndef PRODUCT 523 // Support for PromotionFailureALot. Return true if it's time to cause a 524 // promotion failure. The no-argument version uses 525 // this->_promotion_failure_alot_count as the counter. 526 bool promotion_should_fail(volatile size_t* count); 527 bool promotion_should_fail(); 528 529 // Reset the PromotionFailureALot counters. Should be called at the end of a 530 // GC in which promotion failure occurred. 531 void reset_promotion_should_fail(volatile size_t* count); 532 void reset_promotion_should_fail(); 533 #endif // #ifndef PRODUCT 534 }; 535 536 // Class to set and reset the GC cause for a CollectedHeap. 537 538 class GCCauseSetter : StackObj { 539 CollectedHeap* _heap; 540 GCCause::Cause _previous_cause; 541 public: 542 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 543 _heap = heap; 544 _previous_cause = _heap->gc_cause(); 545 _heap->set_gc_cause(cause); 546 } 547 548 ~GCCauseSetter() { 549 _heap->set_gc_cause(_previous_cause); 550 } 551 }; 552 553 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP