/* * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP #include "gc/g1/evacuationInfo.hpp" #include "gc/g1/g1BarrierSet.hpp" #include "gc/g1/g1BiasedArray.hpp" #include "gc/g1/g1CardTable.hpp" #include "gc/g1/g1CollectionSet.hpp" #include "gc/g1/g1CollectorState.hpp" #include "gc/g1/g1ConcurrentMark.hpp" #include "gc/g1/g1EdenRegions.hpp" #include "gc/g1/g1EvacFailure.hpp" #include "gc/g1/g1EvacStats.hpp" #include "gc/g1/g1HeapTransition.hpp" #include "gc/g1/g1HeapVerifier.hpp" #include "gc/g1/g1HRPrinter.hpp" #include "gc/g1/g1InCSetState.hpp" #include "gc/g1/g1MonitoringSupport.hpp" #include "gc/g1/g1SurvivorRegions.hpp" #include "gc/g1/g1YCTypes.hpp" #include "gc/g1/heapRegionManager.hpp" #include "gc/g1/heapRegionSet.hpp" #include "gc/shared/barrierSet.hpp" #include "gc/shared/collectedHeap.hpp" #include "gc/shared/gcHeapSummary.hpp" #include "gc/shared/plab.hpp" #include "gc/shared/preservedMarks.hpp" #include "gc/shared/softRefPolicy.hpp" #include "memory/memRegion.hpp" #include "services/memoryManager.hpp" #include "utilities/stack.hpp" // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. // It uses the "Garbage First" heap organization and algorithm, which // may combine concurrent marking with parallel, incremental compaction of // heap subsets that will yield large amounts of garbage. // Forward declarations class HeapRegion; class HRRSCleanupTask; class GenerationSpec; class G1ParScanThreadState; class G1ParScanThreadStateSet; class G1ParScanThreadState; class MemoryPool; class ObjectClosure; class SpaceClosure; class CompactibleSpaceClosure; class Space; class G1CollectionSet; class G1CollectorPolicy; class G1Policy; class G1HotCardCache; class G1RemSet; class G1YoungRemSetSamplingThread; class HeapRegionRemSetIterator; class G1ConcurrentMark; class G1ConcurrentMarkThread; class G1ConcurrentRefine; class GenerationCounters; class STWGCTimer; class G1NewTracer; class EvacuationFailedInfo; class nmethod; class Ticks; class WorkGang; class G1Allocator; class G1ArchiveAllocator; class G1FullGCScope; class G1HeapVerifier; class G1HeapSizingPolicy; class G1HeapSummary; class G1EvacSummary; typedef OverflowTaskQueue RefToScanQueue; typedef GenericTaskQueueSet RefToScanQueueSet; typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) // The G1 STW is alive closure. // An instance is embedded into the G1CH and used as the // (optional) _is_alive_non_header closure in the STW // reference processor. It is also extensively used during // reference processing during STW evacuation pauses. class G1STWIsAliveClosure: public BoolObjectClosure { G1CollectedHeap* _g1h; public: G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} bool do_object_b(oop p); }; class G1RegionMappingChangedListener : public G1MappingChangedListener { private: void reset_from_card_cache(uint start_idx, size_t num_regions); public: virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); }; class G1CollectedHeap : public CollectedHeap { friend class G1FreeCollectionSetTask; friend class VM_CollectForMetadataAllocation; friend class VM_G1CollectForAllocation; friend class VM_G1CollectFull; friend class VMStructs; friend class MutatorAllocRegion; friend class G1FullCollector; friend class G1GCAllocRegion; friend class G1HeapVerifier; // Closures used in implementation. friend class G1ParScanThreadState; friend class G1ParScanThreadStateSet; friend class G1ParTask; friend class G1PLABAllocator; friend class G1PrepareCompactClosure; // Other related classes. friend class HeapRegionClaimer; // Testing classes. friend class G1CheckCSetFastTableClosure; private: G1YoungRemSetSamplingThread* _young_gen_sampling_thread; WorkGang* _workers; G1CollectorPolicy* _collector_policy; G1CardTable* _card_table; SoftRefPolicy _soft_ref_policy; GCMemoryManager _memory_manager; GCMemoryManager _full_gc_memory_manager; MemoryPool* _eden_pool; MemoryPool* _survivor_pool; MemoryPool* _old_pool; static size_t _humongous_object_threshold_in_words; // It keeps track of the old regions. HeapRegionSet _old_set; // It keeps track of the humongous regions. HeapRegionSet _humongous_set; virtual void initialize_serviceability(); void eagerly_reclaim_humongous_regions(); // Start a new incremental collection set for the next pause. void start_new_collection_set(); // The number of regions we could create by expansion. uint _expansion_regions; // The block offset table for the G1 heap. G1BlockOffsetTable* _bot; // Tears down the region sets / lists so that they are empty and the // regions on the heap do not belong to a region set / list. The // only exception is the humongous set which we leave unaltered. If // free_list_only is true, it will only tear down the master free // list. It is called before a Full GC (free_list_only == false) or // before heap shrinking (free_list_only == true). void tear_down_region_sets(bool free_list_only); // Rebuilds the region sets / lists so that they are repopulated to // reflect the contents of the heap. The only exception is the // humongous set which was not torn down in the first place. If // free_list_only is true, it will only rebuild the master free // list. It is called after a Full GC (free_list_only == false) or // after heap shrinking (free_list_only == true). void rebuild_region_sets(bool free_list_only); // Callback for region mapping changed events. G1RegionMappingChangedListener _listener; // The sequence of all heap regions in the heap. HeapRegionManager _hrm; // Manages all allocations with regions except humongous object allocations. G1Allocator* _allocator; // Manages all heap verification. G1HeapVerifier* _verifier; // Outside of GC pauses, the number of bytes used in all regions other // than the current allocation region(s). size_t _summary_bytes_used; void increase_used(size_t bytes); void decrease_used(size_t bytes); void set_used(size_t bytes); // Class that handles archive allocation ranges. G1ArchiveAllocator* _archive_allocator; // GC allocation statistics policy for survivors. G1EvacStats _survivor_evac_stats; // GC allocation statistics policy for tenured objects. G1EvacStats _old_evac_stats; // It specifies whether we should attempt to expand the heap after a // region allocation failure. If heap expansion fails we set this to // false so that we don't re-attempt the heap expansion (it's likely // that subsequent expansion attempts will also fail if one fails). // Currently, it is only consulted during GC and it's reset at the // start of each GC. bool _expand_heap_after_alloc_failure; // Helper for monitoring and management support. G1MonitoringSupport* _g1mm; // Records whether the region at the given index is (still) a // candidate for eager reclaim. Only valid for humongous start // regions; other regions have unspecified values. Humongous start // regions are initialized at start of collection pause, with // candidates removed from the set as they are found reachable from // roots or the young generation. class HumongousReclaimCandidates : public G1BiasedMappedArray { protected: bool default_value() const { return false; } public: void clear() { G1BiasedMappedArray::clear(); } void set_candidate(uint region, bool value) { set_by_index(region, value); } bool is_candidate(uint region) { return get_by_index(region); } }; HumongousReclaimCandidates _humongous_reclaim_candidates; // Stores whether during humongous object registration we found candidate regions. // If not, we can skip a few steps. bool _has_humongous_reclaim_candidates; G1HRPrinter _hr_printer; // It decides whether an explicit GC should start a concurrent cycle // instead of doing a STW GC. Currently, a concurrent cycle is // explicitly started if: // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or // (b) cause == _g1_humongous_allocation // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. // (e) cause == _wb_conc_mark bool should_do_concurrent_full_gc(GCCause::Cause cause); // indicates whether we are in young or mixed GC mode G1CollectorState _collector_state; // Keeps track of how many "old marking cycles" (i.e., Full GCs or // concurrent cycles) we have started. volatile uint _old_marking_cycles_started; // Keeps track of how many "old marking cycles" (i.e., Full GCs or // concurrent cycles) we have completed. volatile uint _old_marking_cycles_completed; // This is a non-product method that is helpful for testing. It is // called at the end of a GC and artificially expands the heap by // allocating a number of dead regions. This way we can induce very // frequent marking cycles and stress the cleanup / concurrent // cleanup code more (as all the regions that will be allocated by // this method will be found dead by the marking cycle). void allocate_dummy_regions() PRODUCT_RETURN; // If the HR printer is active, dump the state of the regions in the // heap after a compaction. void print_hrm_post_compaction(); // Create a memory mapper for auxiliary data structures of the given size and // translation factor. static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, size_t size, size_t translation_factor); void trace_heap(GCWhen::Type when, const GCTracer* tracer); // These are macros so that, if the assert fires, we get the correct // line number, file, etc. #define heap_locking_asserts_params(_extra_message_) \ "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ (_extra_message_), \ BOOL_TO_STR(Heap_lock->owned_by_self()), \ BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ BOOL_TO_STR(Thread::current()->is_VM_thread()) #define assert_heap_locked() \ do { \ assert(Heap_lock->owned_by_self(), \ heap_locking_asserts_params("should be holding the Heap_lock")); \ } while (0) #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ do { \ assert(Heap_lock->owned_by_self() || \ (SafepointSynchronize::is_at_safepoint() && \ ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ heap_locking_asserts_params("should be holding the Heap_lock or " \ "should be at a safepoint")); \ } while (0) #define assert_heap_locked_and_not_at_safepoint() \ do { \ assert(Heap_lock->owned_by_self() && \ !SafepointSynchronize::is_at_safepoint(), \ heap_locking_asserts_params("should be holding the Heap_lock and " \ "should not be at a safepoint")); \ } while (0) #define assert_heap_not_locked() \ do { \ assert(!Heap_lock->owned_by_self(), \ heap_locking_asserts_params("should not be holding the Heap_lock")); \ } while (0) #define assert_heap_not_locked_and_not_at_safepoint() \ do { \ assert(!Heap_lock->owned_by_self() && \ !SafepointSynchronize::is_at_safepoint(), \ heap_locking_asserts_params("should not be holding the Heap_lock and " \ "should not be at a safepoint")); \ } while (0) #define assert_at_safepoint_on_vm_thread() \ do { \ assert_at_safepoint(); \ assert(Thread::current_or_null() != NULL, "no current thread"); \ assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ } while (0) // The young region list. G1EdenRegions _eden; G1SurvivorRegions _survivor; STWGCTimer* _gc_timer_stw; G1NewTracer* _gc_tracer_stw; // The current policy object for the collector. G1Policy* _g1_policy; G1HeapSizingPolicy* _heap_sizing_policy; G1CollectionSet _collection_set; // Try to allocate a single non-humongous HeapRegion sufficient for // an allocation of the given word_size. If do_expand is true, // attempt to expand the heap if necessary to satisfy the allocation // request. If the region is to be used as an old region or for a // humongous object, set is_old to true. If not, to false. HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); // Initialize a contiguous set of free regions of length num_regions // and starting at index first so that they appear as a single // humongous region. HeapWord* humongous_obj_allocate_initialize_regions(uint first, uint num_regions, size_t word_size); // Attempt to allocate a humongous object of the given size. Return // NULL if unsuccessful. HeapWord* humongous_obj_allocate(size_t word_size); // The following two methods, allocate_new_tlab() and // mem_allocate(), are the two main entry points from the runtime // into the G1's allocation routines. They have the following // assumptions: // // * They should both be called outside safepoints. // // * They should both be called without holding the Heap_lock. // // * All allocation requests for new TLABs should go to // allocate_new_tlab(). // // * All non-TLAB allocation requests should go to mem_allocate(). // // * If either call cannot satisfy the allocation request using the // current allocating region, they will try to get a new one. If // this fails, they will attempt to do an evacuation pause and // retry the allocation. // // * If all allocation attempts fail, even after trying to schedule // an evacuation pause, allocate_new_tlab() will return NULL, // whereas mem_allocate() will attempt a heap expansion and/or // schedule a Full GC. // // * We do not allow humongous-sized TLABs. So, allocate_new_tlab // should never be called with word_size being humongous. All // humongous allocation requests should go to mem_allocate() which // will satisfy them with a special path. virtual HeapWord* allocate_new_tlab(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size); virtual HeapWord* mem_allocate(size_t word_size, bool* gc_overhead_limit_was_exceeded); // First-level mutator allocation attempt: try to allocate out of // the mutator alloc region without taking the Heap_lock. This // should only be used for non-humongous allocations. inline HeapWord* attempt_allocation(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size); // Second-level mutator allocation attempt: take the Heap_lock and // retry the allocation attempt, potentially scheduling a GC // pause. This should only be used for non-humongous allocations. HeapWord* attempt_allocation_slow(size_t word_size); // Takes the Heap_lock and attempts a humongous allocation. It can // potentially schedule a GC pause. HeapWord* attempt_allocation_humongous(size_t word_size); // Allocation attempt that should be called during safepoints (e.g., // at the end of a successful GC). expect_null_mutator_alloc_region // specifies whether the mutator alloc region is expected to be NULL // or not. HeapWord* attempt_allocation_at_safepoint(size_t word_size, bool expect_null_mutator_alloc_region); // These methods are the "callbacks" from the G1AllocRegion class. // For mutator alloc regions. HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); void retire_mutator_alloc_region(HeapRegion* alloc_region, size_t allocated_bytes); // For GC alloc regions. bool has_more_regions(InCSetState dest); HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); void retire_gc_alloc_region(HeapRegion* alloc_region, size_t allocated_bytes, InCSetState dest); // - if explicit_gc is true, the GC is for a System.gc() etc, // otherwise it's for a failed allocation. // - if clear_all_soft_refs is true, all soft references should be // cleared during the GC. // - it returns false if it is unable to do the collection due to the // GC locker being active, true otherwise. bool do_full_collection(bool explicit_gc, bool clear_all_soft_refs); // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. virtual void do_full_collection(bool clear_all_soft_refs); // Resize the heap if necessary after a full collection. void resize_if_necessary_after_full_collection(); // Callback from VM_G1CollectForAllocation operation. // This function does everything necessary/possible to satisfy a // failed allocation request (including collection, expansion, etc.) HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); // Internal helpers used during full GC to split it up to // increase readability. void abort_concurrent_cycle(); void verify_before_full_collection(bool explicit_gc); void prepare_heap_for_full_collection(); void prepare_heap_for_mutators(); void abort_refinement(); void verify_after_full_collection(); void print_heap_after_full_collection(G1HeapTransition* heap_transition); // Helper method for satisfy_failed_allocation() HeapWord* satisfy_failed_allocation_helper(size_t word_size, bool do_gc, bool clear_all_soft_refs, bool expect_null_mutator_alloc_region, bool* gc_succeeded); // Attempting to expand the heap sufficiently // to support an allocation of the given "word_size". If // successful, perform the allocation and return the address of the // allocated block, or else "NULL". HeapWord* expand_and_allocate(size_t word_size); // Preserve any referents discovered by concurrent marking that have not yet been // copied by the STW pause. void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); // Process any reference objects discovered during // an incremental evacuation pause. void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); // Enqueue any remaining discovered references // after processing. void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); // Merges the information gathered on a per-thread basis for all worker threads // during GC into global variables. void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); public: G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } WorkGang* workers() const { return _workers; } G1Allocator* allocator() { return _allocator; } G1HeapVerifier* verifier() { return _verifier; } G1MonitoringSupport* g1mm() { assert(_g1mm != NULL, "should have been initialized"); return _g1mm; } // Expand the garbage-first heap by at least the given size (in bytes!). // Returns true if the heap was expanded by the requested amount; // false otherwise. // (Rounds up to a HeapRegion boundary.) bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); // Returns the PLAB statistics for a given destination. inline G1EvacStats* alloc_buffer_stats(InCSetState dest); // Determines PLAB size for a given destination. inline size_t desired_plab_sz(InCSetState dest); // Do anything common to GC's. void gc_prologue(bool full); void gc_epilogue(bool full); // Does the given region fulfill remembered set based eager reclaim candidate requirements? bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; // Modify the reclaim candidate set and test for presence. // These are only valid for starts_humongous regions. inline void set_humongous_reclaim_candidate(uint region, bool value); inline bool is_humongous_reclaim_candidate(uint region); // Remove from the reclaim candidate set. Also remove from the // collection set so that later encounters avoid the slow path. inline void set_humongous_is_live(oop obj); // Register the given region to be part of the collection set. inline void register_humongous_region_with_cset(uint index); // Register regions with humongous objects (actually on the start region) in // the in_cset_fast_test table. void register_humongous_regions_with_cset(); // We register a region with the fast "in collection set" test. We // simply set to true the array slot corresponding to this region. void register_young_region_with_cset(HeapRegion* r) { _in_cset_fast_test.set_in_young(r->hrm_index()); } void register_old_region_with_cset(HeapRegion* r) { _in_cset_fast_test.set_in_old(r->hrm_index()); } void clear_in_cset(const HeapRegion* hr) { _in_cset_fast_test.clear(hr); } void clear_cset_fast_test() { _in_cset_fast_test.clear(); } bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); // This is called at the start of either a concurrent cycle or a Full // GC to update the number of old marking cycles started. void increment_old_marking_cycles_started(); // This is called at the end of either a concurrent cycle or a Full // GC to update the number of old marking cycles completed. Those two // can happen in a nested fashion, i.e., we start a concurrent // cycle, a Full GC happens half-way through it which ends first, // and then the cycle notices that a Full GC happened and ends // too. The concurrent parameter is a boolean to help us do a bit // tighter consistency checking in the method. If concurrent is // false, the caller is the inner caller in the nesting (i.e., the // Full GC). If concurrent is true, the caller is the outer caller // in this nesting (i.e., the concurrent cycle). Further nesting is // not currently supported. The end of this call also notifies // the FullGCCount_lock in case a Java thread is waiting for a full // GC to happen (e.g., it called System.gc() with // +ExplicitGCInvokesConcurrent). void increment_old_marking_cycles_completed(bool concurrent); uint old_marking_cycles_completed() { return _old_marking_cycles_completed; } G1HRPrinter* hr_printer() { return &_hr_printer; } // Allocates a new heap region instance. HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); // Allocate the highest free region in the reserved heap. This will commit // regions as necessary. HeapRegion* alloc_highest_free_region(); // Frees a non-humongous region by initializing its contents and // adding it to the free list that's passed as a parameter (this is // usually a local list which will be appended to the master free // list later). The used bytes of freed regions are accumulated in // pre_used. If skip_remset is true, the region's RSet will not be freed // up. If skip_hot_card_cache is true, the region's hot card cache will not // be freed up. The assumption is that this will be done later. // The locked parameter indicates if the caller has already taken // care of proper synchronization. This may allow some optimizations. void free_region(HeapRegion* hr, FreeRegionList* free_list, bool skip_remset, bool skip_hot_card_cache = false, bool locked = false); // It dirties the cards that cover the block so that the post // write barrier never queues anything when updating objects on this // block. It is assumed (and in fact we assert) that the block // belongs to a young region. inline void dirty_young_block(HeapWord* start, size_t word_size); // Frees a humongous region by collapsing it into individual regions // and calling free_region() for each of them. The freed regions // will be added to the free list that's passed as a parameter (this // is usually a local list which will be appended to the master free // list later). // The method assumes that only a single thread is ever calling // this for a particular region at once. void free_humongous_region(HeapRegion* hr, FreeRegionList* free_list); // Facility for allocating in 'archive' regions in high heap memory and // recording the allocated ranges. These should all be called from the // VM thread at safepoints, without the heap lock held. They can be used // to create and archive a set of heap regions which can be mapped at the // same fixed addresses in a subsequent JVM invocation. void begin_archive_alloc_range(bool open = false); // Check if the requested size would be too large for an archive allocation. bool is_archive_alloc_too_large(size_t word_size); // Allocate memory of the requested size from the archive region. This will // return NULL if the size is too large or if no memory is available. It // does not trigger a garbage collection. HeapWord* archive_mem_allocate(size_t word_size); // Optionally aligns the end address and returns the allocated ranges in // an array of MemRegions in order of ascending addresses. void end_archive_alloc_range(GrowableArray* ranges, size_t end_alignment_in_bytes = 0); // Facility for allocating a fixed range within the heap and marking // the containing regions as 'archive'. For use at JVM init time, when the // caller may mmap archived heap data at the specified range(s). // Verify that the MemRegions specified in the argument array are within the // reserved heap. bool check_archive_addresses(MemRegion* range, size_t count); // Commit the appropriate G1 regions containing the specified MemRegions // and mark them as 'archive' regions. The regions in the array must be // non-overlapping and in order of ascending address. bool alloc_archive_regions(MemRegion* range, size_t count, bool open); // Insert any required filler objects in the G1 regions around the specified // ranges to make the regions parseable. This must be called after // alloc_archive_regions, and after class loading has occurred. void fill_archive_regions(MemRegion* range, size_t count); // For each of the specified MemRegions, uncommit the containing G1 regions // which had been allocated by alloc_archive_regions. This should be called // rather than fill_archive_regions at JVM init time if the archive file // mapping failed, with the same non-overlapping and sorted MemRegion array. void dealloc_archive_regions(MemRegion* range, size_t count); private: // Shrink the garbage-first heap by at most the given size (in bytes!). // (Rounds down to a HeapRegion boundary.) void shrink(size_t expand_bytes); void shrink_helper(size_t expand_bytes); #if TASKQUEUE_STATS static void print_taskqueue_stats_hdr(outputStream* const st); void print_taskqueue_stats() const; void reset_taskqueue_stats(); #endif // TASKQUEUE_STATS // Schedule the VM operation that will do an evacuation pause to // satisfy an allocation request of word_size. *succeeded will // return whether the VM operation was successful (it did do an // evacuation pause) or not (another thread beat us to it or the GC // locker was active). Given that we should not be holding the // Heap_lock when we enter this method, we will pass the // gc_count_before (i.e., total_collections()) as a parameter since // it has to be read while holding the Heap_lock. Currently, both // methods that call do_collection_pause() release the Heap_lock // before the call, so it's easy to read gc_count_before just before. HeapWord* do_collection_pause(size_t word_size, uint gc_count_before, bool* succeeded, GCCause::Cause gc_cause); void wait_for_root_region_scanning(); // The guts of the incremental collection pause, executed by the vm // thread. It returns false if it is unable to do the collection due // to the GC locker being active, true otherwise bool do_collection_pause_at_safepoint(double target_pause_time_ms); // Actually do the work of evacuating the collection set. void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); void pre_evacuate_collection_set(); void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); // Print the header for the per-thread termination statistics. static void print_termination_stats_hdr(); // Print actual per-thread termination statistics. void print_termination_stats(uint worker_id, double elapsed_ms, double strong_roots_ms, double term_ms, size_t term_attempts, size_t alloc_buffer_waste, size_t undo_waste) const; // Update object copying statistics. void record_obj_copy_mem_stats(); // The hot card cache for remembered set insertion optimization. G1HotCardCache* _hot_card_cache; // The g1 remembered set of the heap. G1RemSet* _g1_rem_set; // A set of cards that cover the objects for which the Rsets should be updated // concurrently after the collection. DirtyCardQueueSet _dirty_card_queue_set; // After a collection pause, convert the regions in the collection set into free // regions. void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); // Abandon the current collection set without recording policy // statistics or updating free lists. void abandon_collection_set(G1CollectionSet* collection_set); // The concurrent marker (and the thread it runs in.) G1ConcurrentMark* _cm; G1ConcurrentMarkThread* _cm_thread; // The concurrent refiner. G1ConcurrentRefine* _cr; // The parallel task queues RefToScanQueueSet *_task_queues; // True iff a evacuation has failed in the current collection. bool _evacuation_failed; EvacuationFailedInfo* _evacuation_failed_info_array; // Failed evacuations cause some logical from-space objects to have // forwarding pointers to themselves. Reset them. void remove_self_forwarding_pointers(); // Restore the objects in the regions in the collection set after an // evacuation failure. void restore_after_evac_failure(); PreservedMarksSet _preserved_marks_set; // Preserve the mark of "obj", if necessary, in preparation for its mark // word being overwritten with a self-forwarding-pointer. void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); #ifndef PRODUCT // Support for forcing evacuation failures. Analogous to // PromotionFailureALot for the other collectors. // Records whether G1EvacuationFailureALot should be in effect // for the current GC bool _evacuation_failure_alot_for_current_gc; // Used to record the GC number for interval checking when // determining whether G1EvaucationFailureALot is in effect // for the current GC. size_t _evacuation_failure_alot_gc_number; // Count of the number of evacuations between failures. volatile size_t _evacuation_failure_alot_count; // Set whether G1EvacuationFailureALot should be in effect // for the current GC (based upon the type of GC and which // command line flags are set); inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, bool during_initial_mark, bool mark_or_rebuild_in_progress); inline void set_evacuation_failure_alot_for_current_gc(); // Return true if it's time to cause an evacuation failure. inline bool evacuation_should_fail(); // Reset the G1EvacuationFailureALot counters. Should be called at // the end of an evacuation pause in which an evacuation failure occurred. inline void reset_evacuation_should_fail(); #endif // !PRODUCT // ("Weak") Reference processing support. // // G1 has 2 instances of the reference processor class. One // (_ref_processor_cm) handles reference object discovery // and subsequent processing during concurrent marking cycles. // // The other (_ref_processor_stw) handles reference object // discovery and processing during full GCs and incremental // evacuation pauses. // // During an incremental pause, reference discovery will be // temporarily disabled for _ref_processor_cm and will be // enabled for _ref_processor_stw. At the end of the evacuation // pause references discovered by _ref_processor_stw will be // processed and discovery will be disabled. The previous // setting for reference object discovery for _ref_processor_cm // will be re-instated. // // At the start of marking: // * Discovery by the CM ref processor is verified to be inactive // and it's discovered lists are empty. // * Discovery by the CM ref processor is then enabled. // // At the end of marking: // * Any references on the CM ref processor's discovered // lists are processed (possibly MT). // // At the start of full GC we: // * Disable discovery by the CM ref processor and // empty CM ref processor's discovered lists // (without processing any entries). // * Verify that the STW ref processor is inactive and it's // discovered lists are empty. // * Temporarily set STW ref processor discovery as single threaded. // * Temporarily clear the STW ref processor's _is_alive_non_header // field. // * Finally enable discovery by the STW ref processor. // // The STW ref processor is used to record any discovered // references during the full GC. // // At the end of a full GC we: // * Enqueue any reference objects discovered by the STW ref processor // that have non-live referents. This has the side-effect of // making the STW ref processor inactive by disabling discovery. // * Verify that the CM ref processor is still inactive // and no references have been placed on it's discovered // lists (also checked as a precondition during initial marking). // The (stw) reference processor... ReferenceProcessor* _ref_processor_stw; // During reference object discovery, the _is_alive_non_header // closure (if non-null) is applied to the referent object to // determine whether the referent is live. If so then the // reference object does not need to be 'discovered' and can // be treated as a regular oop. This has the benefit of reducing // the number of 'discovered' reference objects that need to // be processed. // // Instance of the is_alive closure for embedding into the // STW reference processor as the _is_alive_non_header field. // Supplying a value for the _is_alive_non_header field is // optional but doing so prevents unnecessary additions to // the discovered lists during reference discovery. G1STWIsAliveClosure _is_alive_closure_stw; // The (concurrent marking) reference processor... ReferenceProcessor* _ref_processor_cm; // Instance of the concurrent mark is_alive closure for embedding // into the Concurrent Marking reference processor as the // _is_alive_non_header field. Supplying a value for the // _is_alive_non_header field is optional but doing so prevents // unnecessary additions to the discovered lists during reference // discovery. G1CMIsAliveClosure _is_alive_closure_cm; public: RefToScanQueue *task_queue(uint i) const; uint num_task_queues() const; // A set of cards where updates happened during the GC DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } // Create a G1CollectedHeap with the specified policy. // Must call the initialize method afterwards. // May not return if something goes wrong. G1CollectedHeap(G1CollectorPolicy* policy); private: jint initialize_concurrent_refinement(); jint initialize_young_gen_sampling_thread(); public: // Initialize the G1CollectedHeap to have the initial and // maximum sizes and remembered and barrier sets // specified by the policy object. jint initialize(); virtual void stop(); virtual void safepoint_synchronize_begin(); virtual void safepoint_synchronize_end(); // Return the (conservative) maximum heap alignment for any G1 heap static size_t conservative_max_heap_alignment(); // Does operations required after initialization has been done. void post_initialize(); // Initialize weak reference processing. void ref_processing_init(); virtual Name kind() const { return CollectedHeap::G1; } virtual const char* name() const { return "G1"; } const G1CollectorState* collector_state() const { return &_collector_state; } G1CollectorState* collector_state() { return &_collector_state; } // The current policy object for the collector. G1Policy* g1_policy() const { return _g1_policy; } const G1CollectionSet* collection_set() const { return &_collection_set; } G1CollectionSet* collection_set() { return &_collection_set; } virtual CollectorPolicy* collector_policy() const; virtual SoftRefPolicy* soft_ref_policy(); virtual GrowableArray memory_managers(); virtual GrowableArray memory_pools(); // The rem set and barrier set. G1RemSet* g1_rem_set() const { return _g1_rem_set; } // Try to minimize the remembered set. void scrub_rem_set(); // Apply the given closure on all cards in the Hot Card Cache, emptying it. void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); // The shared block offset table array. G1BlockOffsetTable* bot() const { return _bot; } // Reference Processing accessors // The STW reference processor.... ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } // The Concurrent Marking reference processor... ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } size_t unused_committed_regions_in_bytes() const; virtual size_t capacity() const; virtual size_t used() const; // This should be called when we're not holding the heap lock. The // result might be a bit inaccurate. size_t used_unlocked() const; size_t recalculate_used() const; // These virtual functions do the actual allocation. // Some heaps may offer a contiguous region for shared non-blocking // allocation, via inlined code (by exporting the address of the top and // end fields defining the extent of the contiguous allocation region.) // But G1CollectedHeap doesn't yet support this. virtual bool is_maximal_no_gc() const { return _hrm.available() == 0; } // Returns whether there are any regions left in the heap for allocation. bool has_regions_left_for_allocation() const { return !is_maximal_no_gc() || num_free_regions() != 0; } // The current number of regions in the heap. uint num_regions() const { return _hrm.length(); } // The max number of regions in the heap. uint max_regions() const { return _hrm.max_length(); } // The number of regions that are completely free. uint num_free_regions() const { return _hrm.num_free_regions(); } MemoryUsage get_auxiliary_data_memory_usage() const { return _hrm.get_auxiliary_data_memory_usage(); } // The number of regions that are not completely free. uint num_used_regions() const { return num_regions() - num_free_regions(); } #ifdef ASSERT bool is_on_master_free_list(HeapRegion* hr) { return _hrm.is_free(hr); } #endif // ASSERT inline void old_set_add(HeapRegion* hr); inline void old_set_remove(HeapRegion* hr); size_t non_young_capacity_bytes() { return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; } // Determine whether the given region is one that we are using as an // old GC alloc region. bool is_old_gc_alloc_region(HeapRegion* hr); // Perform a collection of the heap; intended for use in implementing // "System.gc". This probably implies as full a collection as the // "CollectedHeap" supports. virtual void collect(GCCause::Cause cause); // True iff an evacuation has failed in the most-recent collection. bool evacuation_failed() { return _evacuation_failed; } void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); void prepend_to_freelist(FreeRegionList* list); void decrement_summary_bytes(size_t bytes); virtual bool is_in(const void* p) const; #ifdef ASSERT // Returns whether p is in one of the available areas of the heap. Slow but // extensive version. bool is_in_exact(const void* p) const; #endif // Return "TRUE" iff the given object address is within the collection // set. Assumes that the reference points into the heap. inline bool is_in_cset(const HeapRegion *hr); inline bool is_in_cset(oop obj); inline bool is_in_cset(HeapWord* addr); inline bool is_in_cset_or_humongous(const oop obj); private: // This array is used for a quick test on whether a reference points into // the collection set or not. Each of the array's elements denotes whether the // corresponding region is in the collection set or not. G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; public: inline InCSetState in_cset_state(const oop obj); // Return "TRUE" iff the given object address is in the reserved // region of g1. bool is_in_g1_reserved(const void* p) const { return _hrm.reserved().contains(p); } // Returns a MemRegion that corresponds to the space that has been // reserved for the heap MemRegion g1_reserved() const { return _hrm.reserved(); } virtual bool is_in_closed_subset(const void* p) const; G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } G1CardTable* card_table() const { return _card_table; } // Iteration functions. // Iterate over all objects, calling "cl.do_object" on each. virtual void object_iterate(ObjectClosure* cl); virtual void safe_object_iterate(ObjectClosure* cl) { object_iterate(cl); } // Iterate over heap regions, in address order, terminating the // iteration early if the "do_heap_region" method returns "true". void heap_region_iterate(HeapRegionClosure* blk) const; // Return the region with the given index. It assumes the index is valid. inline HeapRegion* region_at(uint index) const; // Return the next region (by index) that is part of the same // humongous object that hr is part of. inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; // Calculate the region index of the given address. Given address must be // within the heap. inline uint addr_to_region(HeapWord* addr) const; inline HeapWord* bottom_addr_for_region(uint index) const; // Two functions to iterate over the heap regions in parallel. Threads // compete using the HeapRegionClaimer to claim the regions before // applying the closure on them. // The _from_worker_offset version uses the HeapRegionClaimer and // the worker id to calculate a start offset to prevent all workers to // start from the point. void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, HeapRegionClaimer* hrclaimer, uint worker_id) const; void heap_region_par_iterate_from_start(HeapRegionClosure* cl, HeapRegionClaimer* hrclaimer) const; // Iterate over the regions (if any) in the current collection set. void collection_set_iterate(HeapRegionClosure* blk); // Iterate over the regions (if any) in the current collection set. Starts the // iteration over the entire collection set so that the start regions of a given // worker id over the set active_workers are evenly spread across the set of // collection set regions. void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); // Returns the HeapRegion that contains addr. addr must not be NULL. template inline HeapRegion* heap_region_containing(const T addr) const; // A CollectedHeap is divided into a dense sequence of "blocks"; that is, // each address in the (reserved) heap is a member of exactly // one block. The defining characteristic of a block is that it is // possible to find its size, and thus to progress forward to the next // block. (Blocks may be of different sizes.) Thus, blocks may // represent Java objects, or they might be free blocks in a // free-list-based heap (or subheap), as long as the two kinds are // distinguishable and the size of each is determinable. // Returns the address of the start of the "block" that contains the // address "addr". We say "blocks" instead of "object" since some heaps // may not pack objects densely; a chunk may either be an object or a // non-object. virtual HeapWord* block_start(const void* addr) const; // Requires "addr" to be the start of a chunk, and returns its size. // "addr + size" is required to be the start of a new chunk, or the end // of the active area of the heap. virtual size_t block_size(const HeapWord* addr) const; // Requires "addr" to be the start of a block, and returns "TRUE" iff // the block is an object. virtual bool block_is_obj(const HeapWord* addr) const; // Section on thread-local allocation buffers (TLABs) // See CollectedHeap for semantics. bool supports_tlab_allocation() const; size_t tlab_capacity(Thread* ignored) const; size_t tlab_used(Thread* ignored) const; size_t max_tlab_size() const; size_t unsafe_max_tlab_alloc(Thread* ignored) const; inline bool is_in_young(const oop obj); // Returns "true" iff the given word_size is "very large". static bool is_humongous(size_t word_size) { // Note this has to be strictly greater-than as the TLABs // are capped at the humongous threshold and we want to // ensure that we don't try to allocate a TLAB as // humongous and that we don't allocate a humongous // object in a TLAB. return word_size > _humongous_object_threshold_in_words; } // Returns the humongous threshold for a specific region size static size_t humongous_threshold_for(size_t region_size) { return (region_size / 2); } // Returns the number of regions the humongous object of the given word size // requires. static size_t humongous_obj_size_in_regions(size_t word_size); // Print the maximum heap capacity. virtual size_t max_capacity() const; virtual jlong millis_since_last_gc(); // Convenience function to be used in situations where the heap type can be // asserted to be this type. static G1CollectedHeap* heap(); void set_region_short_lived_locked(HeapRegion* hr); // add appropriate methods for any other surv rate groups const G1SurvivorRegions* survivor() const { return &_survivor; } uint survivor_regions_count() const { return _survivor.length(); } uint eden_regions_count() const { return _eden.length(); } uint young_regions_count() const { return _eden.length() + _survivor.length(); } uint old_regions_count() const { return _old_set.length(); } uint humongous_regions_count() const { return _humongous_set.length(); } #ifdef ASSERT bool check_young_list_empty(); #endif // *** Stuff related to concurrent marking. It's not clear to me that so // many of these need to be public. // The functions below are helper functions that a subclass of // "CollectedHeap" can use in the implementation of its virtual // functions. // This performs a concurrent marking of the live objects in a // bitmap off to the side. void do_concurrent_mark(); bool is_marked_next(oop obj) const; // Determine if an object is dead, given the object and also // the region to which the object belongs. An object is dead // iff a) it was not allocated since the last mark, b) it // is not marked, and c) it is not in an archive region. bool is_obj_dead(const oop obj, const HeapRegion* hr) const { return hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && !hr->is_archive(); } // This function returns true when an object has been // around since the previous marking and hasn't yet // been marked during this marking, and is not in an archive region. bool is_obj_ill(const oop obj, const HeapRegion* hr) const { return !hr->obj_allocated_since_next_marking(obj) && !is_marked_next(obj) && !hr->is_archive(); } // Determine if an object is dead, given only the object itself. // This will find the region to which the object belongs and // then call the region version of the same function. // Added if it is NULL it isn't dead. inline bool is_obj_dead(const oop obj) const; inline bool is_obj_ill(const oop obj) const; inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; inline bool is_obj_dead_full(const oop obj) const; G1ConcurrentMark* concurrent_mark() const { return _cm; } // Refinement G1ConcurrentRefine* concurrent_refine() const { return _cr; } // Optimized nmethod scanning support routines // Is an oop scavengeable virtual bool is_scavengable(oop obj); // Register the given nmethod with the G1 heap. virtual void register_nmethod(nmethod* nm); // Unregister the given nmethod from the G1 heap. virtual void unregister_nmethod(nmethod* nm); // Free up superfluous code root memory. void purge_code_root_memory(); // Rebuild the strong code root lists for each region // after a full GC. void rebuild_strong_code_roots(); // Partial cleaning used when class unloading is disabled. // Let the caller choose what structures to clean out: // - StringTable // - SymbolTable // - StringDeduplication structures void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); // Complete cleaning used when class unloading is enabled. // Cleans out all structures handled by partial_cleaning and also the CodeCache. void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); // Redirty logged cards in the refinement queue. void redirty_logged_cards(); // Verification // Perform any cleanup actions necessary before allowing a verification. virtual void prepare_for_verify(); // Perform verification. // vo == UsePrevMarking -> use "prev" marking information, // vo == UseNextMarking -> use "next" marking information // vo == UseFullMarking -> use "next" marking bitmap but no TAMS // // NOTE: Only the "prev" marking information is guaranteed to be // consistent most of the time, so most calls to this should use // vo == UsePrevMarking. // Currently, there is only one case where this is called with // vo == UseNextMarking, which is to verify the "next" marking // information at the end of remark. // Currently there is only one place where this is called with // vo == UseFullMarking, which is to verify the marking during a // full GC. void verify(VerifyOption vo); // WhiteBox testing support. virtual bool supports_concurrent_phase_control() const; virtual const char* const* concurrent_phases() const; virtual bool request_concurrent_phase(const char* phase); // The methods below are here for convenience and dispatch the // appropriate method depending on value of the given VerifyOption // parameter. The values for that parameter, and their meanings, // are the same as those above. bool is_obj_dead_cond(const oop obj, const HeapRegion* hr, const VerifyOption vo) const; bool is_obj_dead_cond(const oop obj, const VerifyOption vo) const; G1HeapSummary create_g1_heap_summary(); G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); // Printing private: void print_heap_regions() const; void print_regions_on(outputStream* st) const; public: virtual void print_on(outputStream* st) const; virtual void print_extended_on(outputStream* st) const; virtual void print_on_error(outputStream* st) const; virtual void print_gc_threads_on(outputStream* st) const; virtual void gc_threads_do(ThreadClosure* tc) const; // Override void print_tracing_info() const; // The following two methods are helpful for debugging RSet issues. void print_cset_rsets() PRODUCT_RETURN; void print_all_rsets() PRODUCT_RETURN; public: size_t pending_card_num(); private: size_t _max_heap_capacity; }; class G1ParEvacuateFollowersClosure : public VoidClosure { private: double _start_term; double _term_time; size_t _term_attempts; void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } void end_term_time() { _term_time += os::elapsedTime() - _start_term; } protected: G1CollectedHeap* _g1h; G1ParScanThreadState* _par_scan_state; RefToScanQueueSet* _queues; ParallelTaskTerminator* _terminator; G1ParScanThreadState* par_scan_state() { return _par_scan_state; } RefToScanQueueSet* queues() { return _queues; } ParallelTaskTerminator* terminator() { return _terminator; } public: G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, G1ParScanThreadState* par_scan_state, RefToScanQueueSet* queues, ParallelTaskTerminator* terminator) : _g1h(g1h), _par_scan_state(par_scan_state), _queues(queues), _terminator(terminator), _start_term(0.0), _term_time(0.0), _term_attempts(0) {} void do_void(); double term_time() const { return _term_time; } size_t term_attempts() const { return _term_attempts; } private: inline bool offer_termination(); }; #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP