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.
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  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).
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  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
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  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   // Print any relevant tracing info that flags imply.
 471   // Default implementation does nothing.
 472   virtual void print_tracing_info() const = 0;
 473 
 474   void print_heap_before_gc();
 475   void print_heap_after_gc();
 476 
 477   // Registering and unregistering an nmethod (compiled code) with the heap.
 478   virtual void register_nmethod(nmethod* nm) = 0;
 479   virtual void unregister_nmethod(nmethod* nm) = 0;
 480   // Callback for when nmethod is about to be deleted.
 481   virtual void flush_nmethod(nmethod* nm) = 0;
 482   virtual void verify_nmethod(nmethod* nm) = 0;
 483 
 484   void trace_heap_before_gc(const GCTracer* gc_tracer);
 485   void trace_heap_after_gc(const GCTracer* gc_tracer);
 486 
 487   // Heap verification
 488   virtual void verify(VerifyOption option) = 0;
 489 
 490   // Return true if concurrent gc control via WhiteBox is supported by
 491   // this collector.  The default implementation returns false.
 492   virtual bool supports_concurrent_gc_breakpoints() const;
 493 
 494   // Provides a thread pool to SafepointSynchronize to use
 495   // for parallel safepoint cleanup.
 496   // GCs that use a GC worker thread pool may want to share
 497   // it for use during safepoint cleanup. This is only possible
 498   // if the GC can pause and resume concurrent work (e.g. G1
 499   // concurrent marking) for an intermittent non-GC safepoint.
 500   // If this method returns NULL, SafepointSynchronize will
 501   // perform cleanup tasks serially in the VMThread.
 502   virtual WorkGang* get_safepoint_workers() { return NULL; }
 503 
 504   // Support for object pinning. This is used by JNI Get*Critical()
 505   // and Release*Critical() family of functions. If supported, the GC
 506   // must guarantee that pinned objects never move.
 507   virtual bool supports_object_pinning() const;
 508   virtual oop pin_object(JavaThread* thread, oop obj);
 509   virtual void unpin_object(JavaThread* thread, oop obj);
 510 
 511   // Deduplicate the string, iff the GC supports string deduplication.
 512   virtual void deduplicate_string(oop str);
 513 
 514   virtual bool is_oop(oop object) const;
 515 
 516   // Non product verification and debugging.
 517 #ifndef PRODUCT
 518   // Support for PromotionFailureALot.  Return true if it's time to cause a
 519   // promotion failure.  The no-argument version uses
 520   // this->_promotion_failure_alot_count as the counter.
 521   bool promotion_should_fail(volatile size_t* count);
 522   bool promotion_should_fail();
 523 
 524   // Reset the PromotionFailureALot counters.  Should be called at the end of a
 525   // GC in which promotion failure occurred.
 526   void reset_promotion_should_fail(volatile size_t* count);
 527   void reset_promotion_should_fail();
 528 #endif  // #ifndef PRODUCT
 529 };
 530 
 531 // Class to set and reset the GC cause for a CollectedHeap.
 532 
 533 class GCCauseSetter : StackObj {
 534   CollectedHeap* _heap;
 535   GCCause::Cause _previous_cause;
 536  public:
 537   GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
 538     _heap = heap;
 539     _previous_cause = _heap->gc_cause();
 540     _heap->set_gc_cause(cause);
 541   }
 542 
 543   ~GCCauseSetter() {
 544     _heap->set_gc_cause(_previous_cause);
 545   }
 546 };
 547 
 548 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP
--- EOF ---