8200426: Make G1 code use _g1h members
Summary: Consistently use _g1h member names for cached G1CollectedHeap* variables.
Reviewed-by: sangheki, sjohanss
/*
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#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<StarTask, mtGC> RefToScanQueue;
typedef GenericTaskQueueSet<RefToScanQueue, mtGC> 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<bool> {
protected:
bool default_value() const { return false; }
public:
void clear() { G1BiasedMappedArray<bool>::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 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 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<MemRegion>* 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<GCMemoryManager*> memory_managers();
virtual GrowableArray<MemoryPool*> 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 <class T>
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