1 /* 2 * Copyright (c) 2001, 2019, 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 "memory/allocation.hpp" 31 #include "runtime/handles.hpp" 32 #include "runtime/perfData.hpp" 33 #include "runtime/safepoint.hpp" 34 #include "services/memoryUsage.hpp" 35 #include "utilities/debug.hpp" 36 #include "utilities/events.hpp" 37 #include "utilities/formatBuffer.hpp" 38 #include "utilities/growableArray.hpp" 39 40 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 41 // is an abstract class: there may be many different kinds of heaps. This 42 // class defines the functions that a heap must implement, and contains 43 // infrastructure common to all heaps. 44 45 class AdaptiveSizePolicy; 46 class BarrierSet; 47 class CollectorPolicy; 48 class GCHeapSummary; 49 class GCTimer; 50 class GCTracer; 51 class GCMemoryManager; 52 class MemoryPool; 53 class MetaspaceSummary; 54 class SoftRefPolicy; 55 class Thread; 56 class ThreadClosure; 57 class VirtualSpaceSummary; 58 class WorkGang; 59 class nmethod; 60 61 class GCMessage : public FormatBuffer<1024> { 62 public: 63 bool is_before; 64 65 public: 66 GCMessage() {} 67 }; 68 69 class CollectedHeap; 70 71 class GCHeapLog : public EventLogBase<GCMessage> { 72 private: 73 void log_heap(CollectedHeap* heap, bool before); 74 75 public: 76 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {} 77 78 void log_heap_before(CollectedHeap* heap) { 79 log_heap(heap, true); 80 } 81 void log_heap_after(CollectedHeap* heap) { 82 log_heap(heap, false); 83 } 84 }; 85 86 // 87 // CollectedHeap 88 // GenCollectedHeap 89 // SerialHeap 90 // CMSHeap 91 // G1CollectedHeap 92 // ParallelScavengeHeap 93 // ShenandoahHeap 94 // ZCollectedHeap 95 // 96 class CollectedHeap : public CHeapObj<mtInternal> { 97 friend class VMStructs; 98 friend class JVMCIVMStructs; 99 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 100 friend class MemAllocator; 101 102 private: 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 // To allow more flexible TLAB allocations min_size specifies 130 // the minimum size needed, while requested_size is the requested 131 // size based on ergonomics. The actually allocated size will be 132 // returned in actual_size. 133 virtual HeapWord* allocate_new_tlab(size_t min_size, 134 size_t requested_size, 135 size_t* actual_size); 136 137 // Reinitialize tlabs before resuming mutators. 138 virtual void resize_all_tlabs(); 139 140 // Raw memory allocation facilities 141 // The obj and array allocate methods are covers for these methods. 142 // mem_allocate() should never be 143 // called to allocate TLABs, only individual objects. 144 virtual HeapWord* mem_allocate(size_t size, 145 bool* gc_overhead_limit_was_exceeded) = 0; 146 147 // Filler object utilities. 148 static inline size_t filler_array_hdr_size(); 149 static inline size_t filler_array_min_size(); 150 151 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 152 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 153 154 // Fill with a single array; caller must ensure filler_array_min_size() <= 155 // words <= filler_array_max_size(). 156 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 157 158 // Fill with a single object (either an int array or a java.lang.Object). 159 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 160 161 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 162 163 // Verification functions 164 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 165 PRODUCT_RETURN; 166 debug_only(static void check_for_valid_allocation_state();) 167 168 public: 169 enum Name { 170 None, 171 Serial, 172 Parallel, 173 CMS, 174 G1, 175 Epsilon, 176 Z, 177 Shenandoah 178 }; 179 180 static inline size_t filler_array_max_size() { 181 return _filler_array_max_size; 182 } 183 184 virtual Name kind() const = 0; 185 186 virtual const char* name() const = 0; 187 188 /** 189 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 190 * and JNI_OK on success. 191 */ 192 virtual jint initialize() = 0; 193 194 // In many heaps, there will be a need to perform some initialization activities 195 // after the Universe is fully formed, but before general heap allocation is allowed. 196 // This is the correct place to place such initialization methods. 197 virtual void post_initialize(); 198 199 // Stop any onging concurrent work and prepare for exit. 200 virtual void stop() {} 201 202 // Stop and resume concurrent GC threads interfering with safepoint operations 203 virtual void safepoint_synchronize_begin() {} 204 virtual void safepoint_synchronize_end() {} 205 206 void initialize_reserved_region(HeapWord *start, HeapWord *end); 207 MemRegion reserved_region() const { return _reserved; } 208 address base() const { return (address)reserved_region().start(); } 209 210 virtual size_t capacity() const = 0; 211 virtual size_t used() const = 0; 212 213 // Return "true" if the part of the heap that allocates Java 214 // objects has reached the maximal committed limit that it can 215 // reach, without a garbage collection. 216 virtual bool is_maximal_no_gc() const = 0; 217 218 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 219 // memory that the vm could make available for storing 'normal' java objects. 220 // This is based on the reserved address space, but should not include space 221 // that the vm uses internally for bookkeeping or temporary storage 222 // (e.g., in the case of the young gen, one of the survivor 223 // spaces). 224 virtual size_t max_capacity() const = 0; 225 226 // Returns "TRUE" if "p" points into the reserved area of the heap. 227 bool is_in_reserved(const void* p) const { 228 return _reserved.contains(p); 229 } 230 231 bool is_in_reserved_or_null(const void* p) const { 232 return p == NULL || is_in_reserved(p); 233 } 234 235 // Returns "TRUE" iff "p" points into the committed areas of the heap. 236 // This method can be expensive so avoid using it in performance critical 237 // code. 238 virtual bool is_in(const void* p) const = 0; 239 240 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 241 242 void set_gc_cause(GCCause::Cause v) { 243 if (UsePerfData) { 244 _gc_lastcause = _gc_cause; 245 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 246 _perf_gc_cause->set_value(GCCause::to_string(v)); 247 } 248 _gc_cause = v; 249 } 250 GCCause::Cause gc_cause() { return _gc_cause; } 251 252 virtual oop obj_allocate(Klass* klass, int size, TRAPS); 253 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 254 virtual oop class_allocate(Klass* klass, int size, TRAPS); 255 256 // Utilities for turning raw memory into filler objects. 257 // 258 // min_fill_size() is the smallest region that can be filled. 259 // fill_with_objects() can fill arbitrary-sized regions of the heap using 260 // multiple objects. fill_with_object() is for regions known to be smaller 261 // than the largest array of integers; it uses a single object to fill the 262 // region and has slightly less overhead. 263 static size_t min_fill_size() { 264 return size_t(align_object_size(oopDesc::header_size())); 265 } 266 267 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 268 269 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 270 static void fill_with_object(MemRegion region, bool zap = true) { 271 fill_with_object(region.start(), region.word_size(), zap); 272 } 273 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 274 fill_with_object(start, pointer_delta(end, start), zap); 275 } 276 277 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 278 virtual size_t min_dummy_object_size() const; 279 size_t tlab_alloc_reserve() const; 280 281 // Return the address "addr" aligned by "alignment_in_bytes" if such 282 // an address is below "end". Return NULL otherwise. 283 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 284 HeapWord* end, 285 unsigned short alignment_in_bytes); 286 287 // Some heaps may offer a contiguous region for shared non-blocking 288 // allocation, via inlined code (by exporting the address of the top and 289 // end fields defining the extent of the contiguous allocation region.) 290 291 // This function returns "true" iff the heap supports this kind of 292 // allocation. (Default is "no".) 293 virtual bool supports_inline_contig_alloc() const { 294 return false; 295 } 296 // These functions return the addresses of the fields that define the 297 // boundaries of the contiguous allocation area. (These fields should be 298 // physically near to one another.) 299 virtual HeapWord* volatile* top_addr() const { 300 guarantee(false, "inline contiguous allocation not supported"); 301 return NULL; 302 } 303 virtual HeapWord** end_addr() const { 304 guarantee(false, "inline contiguous allocation not supported"); 305 return NULL; 306 } 307 308 // Some heaps may be in an unparseable state at certain times between 309 // collections. This may be necessary for efficient implementation of 310 // certain allocation-related activities. Calling this function before 311 // attempting to parse a heap ensures that the heap is in a parsable 312 // state (provided other concurrent activity does not introduce 313 // unparsability). It is normally expected, therefore, that this 314 // method is invoked with the world stopped. 315 // NOTE: if you override this method, make sure you call 316 // super::ensure_parsability so that the non-generational 317 // part of the work gets done. See implementation of 318 // CollectedHeap::ensure_parsability and, for instance, 319 // that of GenCollectedHeap::ensure_parsability(). 320 // The argument "retire_tlabs" controls whether existing TLABs 321 // are merely filled or also retired, thus preventing further 322 // allocation from them and necessitating allocation of new TLABs. 323 virtual void ensure_parsability(bool retire_tlabs); 324 325 // Section on thread-local allocation buffers (TLABs) 326 // If the heap supports thread-local allocation buffers, it should override 327 // the following methods: 328 // Returns "true" iff the heap supports thread-local allocation buffers. 329 // The default is "no". 330 virtual bool supports_tlab_allocation() const = 0; 331 332 // The amount of space available for thread-local allocation buffers. 333 virtual size_t tlab_capacity(Thread *thr) const = 0; 334 335 // The amount of used space for thread-local allocation buffers for the given thread. 336 virtual size_t tlab_used(Thread *thr) const = 0; 337 338 virtual size_t max_tlab_size() const; 339 340 // An estimate of the maximum allocation that could be performed 341 // for thread-local allocation buffers without triggering any 342 // collection or expansion activity. 343 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 344 guarantee(false, "thread-local allocation buffers not supported"); 345 return 0; 346 } 347 348 // Perform a collection of the heap; intended for use in implementing 349 // "System.gc". This probably implies as full a collection as the 350 // "CollectedHeap" supports. 351 virtual void collect(GCCause::Cause cause) = 0; 352 353 // Perform a full collection 354 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 355 356 // This interface assumes that it's being called by the 357 // vm thread. It collects the heap assuming that the 358 // heap lock is already held and that we are executing in 359 // the context of the vm thread. 360 virtual void collect_as_vm_thread(GCCause::Cause cause); 361 362 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 363 size_t size, 364 Metaspace::MetadataType mdtype); 365 366 // Returns "true" iff there is a stop-world GC in progress. (I assume 367 // that it should answer "false" for the concurrent part of a concurrent 368 // collector -- dld). 369 bool is_gc_active() const { return _is_gc_active; } 370 371 // Total number of GC collections (started) 372 unsigned int total_collections() const { return _total_collections; } 373 unsigned int total_full_collections() const { return _total_full_collections;} 374 375 // Increment total number of GC collections (started) 376 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 377 void increment_total_collections(bool full = false) { 378 _total_collections++; 379 if (full) { 380 increment_total_full_collections(); 381 } 382 } 383 384 void increment_total_full_collections() { _total_full_collections++; } 385 386 // Return the CollectorPolicy for the heap 387 virtual CollectorPolicy* collector_policy() const = 0; 388 389 // Return the SoftRefPolicy for the heap; 390 virtual SoftRefPolicy* soft_ref_policy() = 0; 391 392 virtual MemoryUsage memory_usage(); 393 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 394 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 395 396 // Iterate over all objects, calling "cl.do_object" on each. 397 virtual void object_iterate(ObjectClosure* cl) = 0; 398 399 // Similar to object_iterate() except iterates only 400 // over live objects. 401 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 402 403 // NOTE! There is no requirement that a collector implement these 404 // functions. 405 // 406 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 407 // each address in the (reserved) heap is a member of exactly 408 // one block. The defining characteristic of a block is that it is 409 // possible to find its size, and thus to progress forward to the next 410 // block. (Blocks may be of different sizes.) Thus, blocks may 411 // represent Java objects, or they might be free blocks in a 412 // free-list-based heap (or subheap), as long as the two kinds are 413 // distinguishable and the size of each is determinable. 414 415 // Returns the address of the start of the "block" that contains the 416 // address "addr". We say "blocks" instead of "object" since some heaps 417 // may not pack objects densely; a chunk may either be an object or a 418 // non-object. 419 virtual HeapWord* block_start(const void* addr) const = 0; 420 421 // Requires "addr" to be the start of a block, and returns "TRUE" iff 422 // the block is an object. 423 virtual bool block_is_obj(const HeapWord* addr) const = 0; 424 425 // Returns the longest time (in ms) that has elapsed since the last 426 // time that any part of the heap was examined by a garbage collection. 427 virtual jlong millis_since_last_gc() = 0; 428 429 // Perform any cleanup actions necessary before allowing a verification. 430 virtual void prepare_for_verify() = 0; 431 432 // Generate any dumps preceding or following a full gc 433 private: 434 void full_gc_dump(GCTimer* timer, bool before); 435 436 virtual void initialize_serviceability() = 0; 437 438 public: 439 void pre_full_gc_dump(GCTimer* timer); 440 void post_full_gc_dump(GCTimer* timer); 441 442 virtual VirtualSpaceSummary create_heap_space_summary(); 443 GCHeapSummary create_heap_summary(); 444 445 MetaspaceSummary create_metaspace_summary(); 446 447 // Print heap information on the given outputStream. 448 virtual void print_on(outputStream* st) const = 0; 449 // The default behavior is to call print_on() on tty. 450 virtual void print() const { 451 print_on(tty); 452 } 453 // Print more detailed heap information on the given 454 // outputStream. The default behavior is to call print_on(). It is 455 // up to each subclass to override it and add any additional output 456 // it needs. 457 virtual void print_extended_on(outputStream* st) const { 458 print_on(st); 459 } 460 461 virtual void print_on_error(outputStream* st) const; 462 463 // Print all GC threads (other than the VM thread) 464 // used by this heap. 465 virtual void print_gc_threads_on(outputStream* st) const = 0; 466 // The default behavior is to call print_gc_threads_on() on tty. 467 void print_gc_threads() { 468 print_gc_threads_on(tty); 469 } 470 // Iterator for all GC threads (other than VM thread) 471 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 472 473 // Print any relevant tracing info that flags imply. 474 // Default implementation does nothing. 475 virtual void print_tracing_info() const = 0; 476 477 void print_heap_before_gc(); 478 void print_heap_after_gc(); 479 480 // Registering and unregistering an nmethod (compiled code) with the heap. 481 // Override with specific mechanism for each specialized heap type. 482 virtual void register_nmethod(nmethod* nm) {} 483 virtual void unregister_nmethod(nmethod* nm) {} 484 virtual void flush_nmethod(nmethod* nm) {} 485 virtual void verify_nmethod(nmethod* nmethod) {} 486 487 void trace_heap_before_gc(const GCTracer* gc_tracer); 488 void trace_heap_after_gc(const GCTracer* gc_tracer); 489 490 // Heap verification 491 virtual void verify(VerifyOption option) = 0; 492 493 // Return true if concurrent phase control (via 494 // request_concurrent_phase_control) is supported by this collector. 495 // The default implementation returns false. 496 virtual bool supports_concurrent_phase_control() const; 497 498 // Request the collector enter the indicated concurrent phase, and 499 // wait until it does so. Supports WhiteBox testing. Only one 500 // request may be active at a time. Phases are designated by name; 501 // the set of names and their meaning is GC-specific. Once the 502 // requested phase has been reached, the collector will attempt to 503 // avoid transitioning to a new phase until a new request is made. 504 // [Note: A collector might not be able to remain in a given phase. 505 // For example, a full collection might cancel an in-progress 506 // concurrent collection.] 507 // 508 // Returns true when the phase is reached. Returns false for an 509 // unknown phase. The default implementation returns false. 510 virtual bool request_concurrent_phase(const char* phase); 511 512 // Provides a thread pool to SafepointSynchronize to use 513 // for parallel safepoint cleanup. 514 // GCs that use a GC worker thread pool may want to share 515 // it for use during safepoint cleanup. This is only possible 516 // if the GC can pause and resume concurrent work (e.g. G1 517 // concurrent marking) for an intermittent non-GC safepoint. 518 // If this method returns NULL, SafepointSynchronize will 519 // perform cleanup tasks serially in the VMThread. 520 virtual WorkGang* get_safepoint_workers() { return NULL; } 521 522 // Support for object pinning. This is used by JNI Get*Critical() 523 // and Release*Critical() family of functions. If supported, the GC 524 // must guarantee that pinned objects never move. 525 virtual bool supports_object_pinning() const; 526 virtual oop pin_object(JavaThread* thread, oop obj); 527 virtual void unpin_object(JavaThread* thread, oop obj); 528 529 // Deduplicate the string, iff the GC supports string deduplication. 530 virtual void deduplicate_string(oop str); 531 532 virtual bool is_oop(oop object) const; 533 534 virtual size_t obj_size(oop obj) const; 535 536 // Cells are memory slices allocated by the allocator. Objects are initialized 537 // in cells. The cell itself may have a header, found at a negative offset of 538 // oops. Usually, the size of the cell header is 0, but it may be larger. 539 virtual ptrdiff_t cell_header_size() const { return 0; } 540 541 // Non product verification and debugging. 542 #ifndef PRODUCT 543 // Support for PromotionFailureALot. Return true if it's time to cause a 544 // promotion failure. The no-argument version uses 545 // this->_promotion_failure_alot_count as the counter. 546 bool promotion_should_fail(volatile size_t* count); 547 bool promotion_should_fail(); 548 549 // Reset the PromotionFailureALot counters. Should be called at the end of a 550 // GC in which promotion failure occurred. 551 void reset_promotion_should_fail(volatile size_t* count); 552 void reset_promotion_should_fail(); 553 #endif // #ifndef PRODUCT 554 }; 555 556 // Class to set and reset the GC cause for a CollectedHeap. 557 558 class GCCauseSetter : StackObj { 559 CollectedHeap* _heap; 560 GCCause::Cause _previous_cause; 561 public: 562 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 563 _heap = heap; 564 _previous_cause = _heap->gc_cause(); 565 _heap->set_gc_cause(cause); 566 } 567 568 ~GCCauseSetter() { 569 _heap->set_gc_cause(_previous_cause); 570 } 571 }; 572 573 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP