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 "gc/shared/verifyOption.hpp" 31 #include "memory/allocation.hpp" 32 #include "runtime/handles.hpp" 33 #include "runtime/perfData.hpp" 34 #include "runtime/safepoint.hpp" 35 #include "services/memoryUsage.hpp" 36 #include "utilities/debug.hpp" 37 #include "utilities/events.hpp" 38 #include "utilities/formatBuffer.hpp" 39 #include "utilities/growableArray.hpp" 40 41 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 42 // is an abstract class: there may be many different kinds of heaps. This 43 // class defines the functions that a heap must implement, and contains 44 // infrastructure common to all heaps. 45 46 class AdaptiveSizePolicy; 47 class BarrierSet; 48 class GCHeapSummary; 49 class GCTimer; 50 class GCTracer; 51 class GCMemoryManager; 52 class MemoryPool; 53 class MetaspaceSummary; 54 class ReservedHeapSpace; 55 class SoftRefPolicy; 56 class Thread; 57 class ThreadClosure; 58 class VirtualSpaceSummary; 59 class WorkGang; 60 class nmethod; 61 62 class GCMessage : public FormatBuffer<1024> { 63 public: 64 bool is_before; 65 66 public: 67 GCMessage() {} 68 }; 69 70 class CollectedHeap; 71 72 class GCHeapLog : public EventLogBase<GCMessage> { 73 private: 74 void log_heap(CollectedHeap* heap, bool before); 75 76 public: 77 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {} 78 79 void log_heap_before(CollectedHeap* heap) { 80 log_heap(heap, true); 81 } 82 void log_heap_after(CollectedHeap* heap) { 83 log_heap(heap, false); 84 } 85 }; 86 87 // 88 // CollectedHeap 89 // GenCollectedHeap 90 // SerialHeap 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 protected: 106 // Not used by all GCs 107 MemRegion _reserved; 108 109 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 // Reinitialize tlabs before resuming mutators. 139 virtual void resize_all_tlabs(); 140 141 // Raw memory allocation facilities 142 // The obj and array allocate methods are covers for these methods. 143 // mem_allocate() should never be 144 // called to allocate TLABs, only individual objects. 145 virtual HeapWord* mem_allocate(size_t size, 146 bool* gc_overhead_limit_was_exceeded) = 0; 147 148 // Filler object utilities. 149 static inline size_t filler_array_hdr_size(); 150 static inline size_t filler_array_min_size(); 151 152 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 153 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 154 155 // Fill with a single array; caller must ensure filler_array_min_size() <= 156 // words <= filler_array_max_size(). 157 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 158 159 // Fill with a single object (either an int array or a java.lang.Object). 160 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 161 162 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 163 164 // Verification functions 165 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 166 PRODUCT_RETURN; 167 debug_only(static void check_for_valid_allocation_state();) 168 169 public: 170 enum Name { 171 None, 172 Serial, 173 Parallel, 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(const ReservedHeapSpace& rs); 207 208 virtual size_t capacity() const = 0; 209 virtual size_t used() const = 0; 210 211 // Returns unused capacity. 212 virtual size_t unused() const; 213 214 // Return "true" if the part of the heap that allocates Java 215 // objects has reached the maximal committed limit that it can 216 // reach, without a garbage collection. 217 virtual bool is_maximal_no_gc() const = 0; 218 219 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 220 // memory that the vm could make available for storing 'normal' java objects. 221 // This is based on the reserved address space, but should not include space 222 // that the vm uses internally for bookkeeping or temporary storage 223 // (e.g., in the case of the young gen, one of the survivor 224 // spaces). 225 virtual size_t max_capacity() const = 0; 226 227 // Returns "TRUE" iff "p" points into the committed areas of the heap. 228 // This method can be expensive so avoid using it in performance critical 229 // code. 230 virtual bool is_in(const void* p) const = 0; 231 232 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 233 234 virtual uint32_t hash_oop(oop obj) const; 235 236 void set_gc_cause(GCCause::Cause v) { 237 if (UsePerfData) { 238 _gc_lastcause = _gc_cause; 239 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 240 _perf_gc_cause->set_value(GCCause::to_string(v)); 241 } 242 _gc_cause = v; 243 } 244 GCCause::Cause gc_cause() { return _gc_cause; } 245 246 oop obj_allocate(Klass* klass, int size, TRAPS); 247 oop obj_buffer_allocate(Klass* klass, int size, TRAPS); // doesn't clear memory 248 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 249 oop class_allocate(Klass* klass, int size, TRAPS); 250 251 // Utilities for turning raw memory into filler objects. 252 // 253 // min_fill_size() is the smallest region that can be filled. 254 // fill_with_objects() can fill arbitrary-sized regions of the heap using 255 // multiple objects. fill_with_object() is for regions known to be smaller 256 // than the largest array of integers; it uses a single object to fill the 257 // region and has slightly less overhead. 258 static size_t min_fill_size() { 259 return size_t(align_object_size(oopDesc::header_size())); 260 } 261 262 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 263 264 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 265 static void fill_with_object(MemRegion region, bool zap = true) { 266 fill_with_object(region.start(), region.word_size(), zap); 267 } 268 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 269 fill_with_object(start, pointer_delta(end, start), zap); 270 } 271 272 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 273 virtual size_t min_dummy_object_size() const; 274 size_t tlab_alloc_reserve() const; 275 276 // Return the address "addr" aligned by "alignment_in_bytes" if such 277 // an address is below "end". Return NULL otherwise. 278 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 279 HeapWord* end, 280 unsigned short alignment_in_bytes); 281 282 // Some heaps may offer a contiguous region for shared non-blocking 283 // allocation, via inlined code (by exporting the address of the top and 284 // end fields defining the extent of the contiguous allocation region.) 285 286 // This function returns "true" iff the heap supports this kind of 287 // allocation. (Default is "no".) 288 virtual bool supports_inline_contig_alloc() const { 289 return false; 290 } 291 // These functions return the addresses of the fields that define the 292 // boundaries of the contiguous allocation area. (These fields should be 293 // physically near to one another.) 294 virtual HeapWord* volatile* top_addr() const { 295 guarantee(false, "inline contiguous allocation not supported"); 296 return NULL; 297 } 298 virtual HeapWord** end_addr() const { 299 guarantee(false, "inline contiguous allocation not supported"); 300 return NULL; 301 } 302 303 // Some heaps may be in an unparseable state at certain times between 304 // collections. This may be necessary for efficient implementation of 305 // certain allocation-related activities. Calling this function before 306 // attempting to parse a heap ensures that the heap is in a parsable 307 // state (provided other concurrent activity does not introduce 308 // unparsability). It is normally expected, therefore, that this 309 // method is invoked with the world stopped. 310 // NOTE: if you override this method, make sure you call 311 // super::ensure_parsability so that the non-generational 312 // part of the work gets done. See implementation of 313 // CollectedHeap::ensure_parsability and, for instance, 314 // that of GenCollectedHeap::ensure_parsability(). 315 // The argument "retire_tlabs" controls whether existing TLABs 316 // are merely filled or also retired, thus preventing further 317 // allocation from them and necessitating allocation of new TLABs. 318 virtual void ensure_parsability(bool retire_tlabs); 319 320 // Section on thread-local allocation buffers (TLABs) 321 // If the heap supports thread-local allocation buffers, it should override 322 // the following methods: 323 // Returns "true" iff the heap supports thread-local allocation buffers. 324 // The default is "no". 325 virtual bool supports_tlab_allocation() const = 0; 326 327 // The amount of space available for thread-local allocation buffers. 328 virtual size_t tlab_capacity(Thread *thr) const = 0; 329 330 // The amount of used space for thread-local allocation buffers for the given thread. 331 virtual size_t tlab_used(Thread *thr) const = 0; 332 333 virtual size_t max_tlab_size() const; 334 335 // An estimate of the maximum allocation that could be performed 336 // for thread-local allocation buffers without triggering any 337 // collection or expansion activity. 338 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 339 guarantee(false, "thread-local allocation buffers not supported"); 340 return 0; 341 } 342 343 // Perform a collection of the heap; intended for use in implementing 344 // "System.gc". This probably implies as full a collection as the 345 // "CollectedHeap" supports. 346 virtual void collect(GCCause::Cause cause) = 0; 347 348 // Perform a full collection 349 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 350 351 // This interface assumes that it's being called by the 352 // vm thread. It collects the heap assuming that the 353 // heap lock is already held and that we are executing in 354 // the context of the vm thread. 355 virtual void collect_as_vm_thread(GCCause::Cause cause); 356 357 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 358 size_t size, 359 Metaspace::MetadataType mdtype); 360 361 // Returns "true" iff there is a stop-world GC in progress. (I assume 362 // that it should answer "false" for the concurrent part of a concurrent 363 // collector -- dld). 364 bool is_gc_active() const { return _is_gc_active; } 365 366 // Total number of GC collections (started) 367 unsigned int total_collections() const { return _total_collections; } 368 unsigned int total_full_collections() const { return _total_full_collections;} 369 370 // Increment total number of GC collections (started) 371 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 372 void increment_total_collections(bool full = false) { 373 _total_collections++; 374 if (full) { 375 increment_total_full_collections(); 376 } 377 } 378 379 void increment_total_full_collections() { _total_full_collections++; } 380 381 // Return the SoftRefPolicy for the heap; 382 virtual SoftRefPolicy* soft_ref_policy() = 0; 383 384 virtual MemoryUsage memory_usage(); 385 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 386 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 387 388 // Iterate over all objects, calling "cl.do_object" on each. 389 virtual void object_iterate(ObjectClosure* cl) = 0; 390 391 // Returns the longest time (in ms) that has elapsed since the last 392 // time that any part of the heap was examined by a garbage collection. 393 virtual jlong millis_since_last_gc() = 0; 394 395 // Perform any cleanup actions necessary before allowing a verification. 396 virtual void prepare_for_verify() = 0; 397 398 // Generate any dumps preceding or following a full gc 399 private: 400 void full_gc_dump(GCTimer* timer, bool before); 401 402 virtual void initialize_serviceability() = 0; 403 404 public: 405 void pre_full_gc_dump(GCTimer* timer); 406 void post_full_gc_dump(GCTimer* timer); 407 408 virtual VirtualSpaceSummary create_heap_space_summary(); 409 GCHeapSummary create_heap_summary(); 410 411 MetaspaceSummary create_metaspace_summary(); 412 413 // Print heap information on the given outputStream. 414 virtual void print_on(outputStream* st) const = 0; 415 // The default behavior is to call print_on() on tty. 416 virtual void print() const; 417 418 // Print more detailed heap information on the given 419 // outputStream. The default behavior is to call print_on(). It is 420 // up to each subclass to override it and add any additional output 421 // it needs. 422 virtual void print_extended_on(outputStream* st) const { 423 print_on(st); 424 } 425 426 virtual void print_on_error(outputStream* st) const; 427 428 // Used to print information about locations in the hs_err file. 429 virtual bool print_location(outputStream* st, void* addr) const = 0; 430 431 // Print all GC threads (other than the VM thread) 432 // used by this heap. 433 virtual void print_gc_threads_on(outputStream* st) const = 0; 434 // The default behavior is to call print_gc_threads_on() on tty. 435 void print_gc_threads() { 436 print_gc_threads_on(tty); 437 } 438 // Iterator for all GC threads (other than VM thread) 439 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 440 441 // Print any relevant tracing info that flags imply. 442 // Default implementation does nothing. 443 virtual void print_tracing_info() const = 0; 444 445 void print_heap_before_gc(); 446 void print_heap_after_gc(); 447 448 // Registering and unregistering an nmethod (compiled code) with the heap. 449 virtual void register_nmethod(nmethod* nm) = 0; 450 virtual void unregister_nmethod(nmethod* nm) = 0; 451 // Callback for when nmethod is about to be deleted. 452 virtual void flush_nmethod(nmethod* nm) = 0; 453 virtual void verify_nmethod(nmethod* nm) = 0; 454 455 void trace_heap_before_gc(const GCTracer* gc_tracer); 456 void trace_heap_after_gc(const GCTracer* gc_tracer); 457 458 // Heap verification 459 virtual void verify(VerifyOption option) = 0; 460 461 // Return true if concurrent phase control (via 462 // request_concurrent_phase_control) is supported by this collector. 463 // The default implementation returns false. 464 virtual bool supports_concurrent_phase_control() const; 465 466 // Request the collector enter the indicated concurrent phase, and 467 // wait until it does so. Supports WhiteBox testing. Only one 468 // request may be active at a time. Phases are designated by name; 469 // the set of names and their meaning is GC-specific. Once the 470 // requested phase has been reached, the collector will attempt to 471 // avoid transitioning to a new phase until a new request is made. 472 // [Note: A collector might not be able to remain in a given phase. 473 // For example, a full collection might cancel an in-progress 474 // concurrent collection.] 475 // 476 // Returns true when the phase is reached. Returns false for an 477 // unknown phase. The default implementation returns false. 478 virtual bool request_concurrent_phase(const char* phase); 479 480 // Provides a thread pool to SafepointSynchronize to use 481 // for parallel safepoint cleanup. 482 // GCs that use a GC worker thread pool may want to share 483 // it for use during safepoint cleanup. This is only possible 484 // if the GC can pause and resume concurrent work (e.g. G1 485 // concurrent marking) for an intermittent non-GC safepoint. 486 // If this method returns NULL, SafepointSynchronize will 487 // perform cleanup tasks serially in the VMThread. 488 virtual WorkGang* get_safepoint_workers() { return NULL; } 489 490 // Support for object pinning. This is used by JNI Get*Critical() 491 // and Release*Critical() family of functions. If supported, the GC 492 // must guarantee that pinned objects never move. 493 virtual bool supports_object_pinning() const; 494 virtual oop pin_object(JavaThread* thread, oop obj); 495 virtual void unpin_object(JavaThread* thread, oop obj); 496 497 // Deduplicate the string, iff the GC supports string deduplication. 498 virtual void deduplicate_string(oop str); 499 500 virtual bool is_oop(oop object) const; 501 502 virtual size_t obj_size(oop obj) const; 503 504 // Non product verification and debugging. 505 #ifndef PRODUCT 506 // Support for PromotionFailureALot. Return true if it's time to cause a 507 // promotion failure. The no-argument version uses 508 // this->_promotion_failure_alot_count as the counter. 509 bool promotion_should_fail(volatile size_t* count); 510 bool promotion_should_fail(); 511 512 // Reset the PromotionFailureALot counters. Should be called at the end of a 513 // GC in which promotion failure occurred. 514 void reset_promotion_should_fail(volatile size_t* count); 515 void reset_promotion_should_fail(); 516 #endif // #ifndef PRODUCT 517 }; 518 519 // Class to set and reset the GC cause for a CollectedHeap. 520 521 class GCCauseSetter : StackObj { 522 CollectedHeap* _heap; 523 GCCause::Cause _previous_cause; 524 public: 525 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 526 _heap = heap; 527 _previous_cause = _heap->gc_cause(); 528 _heap->set_gc_cause(cause); 529 } 530 531 ~GCCauseSetter() { 532 _heap->set_gc_cause(_previous_cause); 533 } 534 }; 535 536 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP