7127708: G1: change task num types from int to uint in concurrent mark
Summary: Change the type of various task num fields, parameters etc to unsigned and rename them to be more consistent with the other collectors. Code changes were also reviewed by Vitaly Davidovich.
Reviewed-by: johnc
Contributed-by: Kaushik Srenevasan <kaushik@twitter.com>
/*
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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
#include "gc_implementation/g1/heapRegionSets.hpp"
#include "utilities/taskqueue.hpp"
class G1CollectedHeap;
class CMTask;
typedef GenericTaskQueue<oop, mtGC> CMTaskQueue;
typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;
// Closure used by CM during concurrent reference discovery
// and reference processing (during remarking) to determine
// if a particular object is alive. It is primarily used
// to determine if referents of discovered reference objects
// are alive. An instance is also embedded into the
// reference processor as the _is_alive_non_header field
class G1CMIsAliveClosure: public BoolObjectClosure {
G1CollectedHeap* _g1;
public:
G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
void do_object(oop obj) {
ShouldNotCallThis();
}
bool do_object_b(oop obj);
};
// A generic CM bit map. This is essentially a wrapper around the BitMap
// class, with one bit per (1<<_shifter) HeapWords.
class CMBitMapRO VALUE_OBJ_CLASS_SPEC {
protected:
HeapWord* _bmStartWord; // base address of range covered by map
size_t _bmWordSize; // map size (in #HeapWords covered)
const int _shifter; // map to char or bit
VirtualSpace _virtual_space; // underlying the bit map
BitMap _bm; // the bit map itself
public:
// constructor
CMBitMapRO(ReservedSpace rs, int shifter);
enum { do_yield = true };
// inquiries
HeapWord* startWord() const { return _bmStartWord; }
size_t sizeInWords() const { return _bmWordSize; }
// the following is one past the last word in space
HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
// read marks
bool isMarked(HeapWord* addr) const {
assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
"outside underlying space?");
return _bm.at(heapWordToOffset(addr));
}
// iteration
inline bool iterate(BitMapClosure* cl, MemRegion mr);
inline bool iterate(BitMapClosure* cl);
// Return the address corresponding to the next marked bit at or after
// "addr", and before "limit", if "limit" is non-NULL. If there is no
// such bit, returns "limit" if that is non-NULL, or else "endWord()".
HeapWord* getNextMarkedWordAddress(HeapWord* addr,
HeapWord* limit = NULL) const;
// Return the address corresponding to the next unmarked bit at or after
// "addr", and before "limit", if "limit" is non-NULL. If there is no
// such bit, returns "limit" if that is non-NULL, or else "endWord()".
HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,
HeapWord* limit = NULL) const;
// conversion utilities
// XXX Fix these so that offsets are size_t's...
HeapWord* offsetToHeapWord(size_t offset) const {
return _bmStartWord + (offset << _shifter);
}
size_t heapWordToOffset(HeapWord* addr) const {
return pointer_delta(addr, _bmStartWord) >> _shifter;
}
int heapWordDiffToOffsetDiff(size_t diff) const;
HeapWord* nextWord(HeapWord* addr) {
return offsetToHeapWord(heapWordToOffset(addr) + 1);
}
// debugging
NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
};
class CMBitMap : public CMBitMapRO {
public:
// constructor
CMBitMap(ReservedSpace rs, int shifter) :
CMBitMapRO(rs, shifter) {}
// write marks
void mark(HeapWord* addr) {
assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
"outside underlying space?");
_bm.set_bit(heapWordToOffset(addr));
}
void clear(HeapWord* addr) {
assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
"outside underlying space?");
_bm.clear_bit(heapWordToOffset(addr));
}
bool parMark(HeapWord* addr) {
assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
"outside underlying space?");
return _bm.par_set_bit(heapWordToOffset(addr));
}
bool parClear(HeapWord* addr) {
assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
"outside underlying space?");
return _bm.par_clear_bit(heapWordToOffset(addr));
}
void markRange(MemRegion mr);
void clearAll();
void clearRange(MemRegion mr);
// Starting at the bit corresponding to "addr" (inclusive), find the next
// "1" bit, if any. This bit starts some run of consecutive "1"'s; find
// the end of this run (stopping at "end_addr"). Return the MemRegion
// covering from the start of the region corresponding to the first bit
// of the run to the end of the region corresponding to the last bit of
// the run. If there is no "1" bit at or after "addr", return an empty
// MemRegion.
MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
};
// Represents a marking stack used by the CM collector.
// Ideally this should be GrowableArray<> just like MSC's marking stack(s).
class CMMarkStack VALUE_OBJ_CLASS_SPEC {
ConcurrentMark* _cm;
oop* _base; // bottom of stack
jint _index; // one more than last occupied index
jint _capacity; // max #elements
jint _saved_index; // value of _index saved at start of GC
NOT_PRODUCT(jint _max_depth;) // max depth plumbed during run
bool _overflow;
DEBUG_ONLY(bool _drain_in_progress;)
DEBUG_ONLY(bool _drain_in_progress_yields;)
public:
CMMarkStack(ConcurrentMark* cm);
~CMMarkStack();
void allocate(size_t size);
oop pop() {
if (!isEmpty()) {
return _base[--_index] ;
}
return NULL;
}
// If overflow happens, don't do the push, and record the overflow.
// *Requires* that "ptr" is already marked.
void push(oop ptr) {
if (isFull()) {
// Record overflow.
_overflow = true;
return;
} else {
_base[_index++] = ptr;
NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
}
}
// Non-block impl. Note: concurrency is allowed only with other
// "par_push" operations, not with "pop" or "drain". We would need
// parallel versions of them if such concurrency was desired.
void par_push(oop ptr);
// Pushes the first "n" elements of "ptr_arr" on the stack.
// Non-block impl. Note: concurrency is allowed only with other
// "par_adjoin_arr" or "push" operations, not with "pop" or "drain".
void par_adjoin_arr(oop* ptr_arr, int n);
// Pushes the first "n" elements of "ptr_arr" on the stack.
// Locking impl: concurrency is allowed only with
// "par_push_arr" and/or "par_pop_arr" operations, which use the same
// locking strategy.
void par_push_arr(oop* ptr_arr, int n);
// If returns false, the array was empty. Otherwise, removes up to "max"
// elements from the stack, and transfers them to "ptr_arr" in an
// unspecified order. The actual number transferred is given in "n" ("n
// == 0" is deliberately redundant with the return value.) Locking impl:
// concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
// operations, which use the same locking strategy.
bool par_pop_arr(oop* ptr_arr, int max, int* n);
// Drain the mark stack, applying the given closure to all fields of
// objects on the stack. (That is, continue until the stack is empty,
// even if closure applications add entries to the stack.) The "bm"
// argument, if non-null, may be used to verify that only marked objects
// are on the mark stack. If "yield_after" is "true", then the
// concurrent marker performing the drain offers to yield after
// processing each object. If a yield occurs, stops the drain operation
// and returns false. Otherwise, returns true.
template<class OopClosureClass>
bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
bool isEmpty() { return _index == 0; }
bool isFull() { return _index == _capacity; }
int maxElems() { return _capacity; }
bool overflow() { return _overflow; }
void clear_overflow() { _overflow = false; }
int size() { return _index; }
void setEmpty() { _index = 0; clear_overflow(); }
// Record the current index.
void note_start_of_gc();
// Make sure that we have not added any entries to the stack during GC.
void note_end_of_gc();
// iterate over the oops in the mark stack, up to the bound recorded via
// the call above.
void oops_do(OopClosure* f);
};
class ForceOverflowSettings VALUE_OBJ_CLASS_SPEC {
private:
#ifndef PRODUCT
uintx _num_remaining;
bool _force;
#endif // !defined(PRODUCT)
public:
void init() PRODUCT_RETURN;
void update() PRODUCT_RETURN;
bool should_force() PRODUCT_RETURN_( return false; );
};
// this will enable a variety of different statistics per GC task
#define _MARKING_STATS_ 0
// this will enable the higher verbose levels
#define _MARKING_VERBOSE_ 0
#if _MARKING_STATS_
#define statsOnly(statement) \
do { \
statement ; \
} while (0)
#else // _MARKING_STATS_
#define statsOnly(statement) \
do { \
} while (0)
#endif // _MARKING_STATS_
typedef enum {
no_verbose = 0, // verbose turned off
stats_verbose, // only prints stats at the end of marking
low_verbose, // low verbose, mostly per region and per major event
medium_verbose, // a bit more detailed than low
high_verbose // per object verbose
} CMVerboseLevel;
class YoungList;
// Root Regions are regions that are not empty at the beginning of a
// marking cycle and which we might collect during an evacuation pause
// while the cycle is active. Given that, during evacuation pauses, we
// do not copy objects that are explicitly marked, what we have to do
// for the root regions is to scan them and mark all objects reachable
// from them. According to the SATB assumptions, we only need to visit
// each object once during marking. So, as long as we finish this scan
// before the next evacuation pause, we can copy the objects from the
// root regions without having to mark them or do anything else to them.
//
// Currently, we only support root region scanning once (at the start
// of the marking cycle) and the root regions are all the survivor
// regions populated during the initial-mark pause.
class CMRootRegions VALUE_OBJ_CLASS_SPEC {
private:
YoungList* _young_list;
ConcurrentMark* _cm;
volatile bool _scan_in_progress;
volatile bool _should_abort;
HeapRegion* volatile _next_survivor;
public:
CMRootRegions();
// We actually do most of the initialization in this method.
void init(G1CollectedHeap* g1h, ConcurrentMark* cm);
// Reset the claiming / scanning of the root regions.
void prepare_for_scan();
// Forces get_next() to return NULL so that the iteration aborts early.
void abort() { _should_abort = true; }
// Return true if the CM thread are actively scanning root regions,
// false otherwise.
bool scan_in_progress() { return _scan_in_progress; }
// Claim the next root region to scan atomically, or return NULL if
// all have been claimed.
HeapRegion* claim_next();
// Flag that we're done with root region scanning and notify anyone
// who's waiting on it. If aborted is false, assume that all regions
// have been claimed.
void scan_finished();
// If CM threads are still scanning root regions, wait until they
// are done. Return true if we had to wait, false otherwise.
bool wait_until_scan_finished();
};
class ConcurrentMarkThread;
class ConcurrentMark: public CHeapObj<mtGC> {
friend class ConcurrentMarkThread;
friend class CMTask;
friend class CMBitMapClosure;
friend class CMGlobalObjectClosure;
friend class CMRemarkTask;
friend class CMConcurrentMarkingTask;
friend class G1ParNoteEndTask;
friend class CalcLiveObjectsClosure;
friend class G1CMRefProcTaskProxy;
friend class G1CMRefProcTaskExecutor;
friend class G1CMParKeepAliveAndDrainClosure;
friend class G1CMParDrainMarkingStackClosure;
protected:
ConcurrentMarkThread* _cmThread; // the thread doing the work
G1CollectedHeap* _g1h; // the heap.
uint _parallel_marking_threads; // the number of marking
// threads we're use
uint _max_parallel_marking_threads; // max number of marking
// threads we'll ever use
double _sleep_factor; // how much we have to sleep, with
// respect to the work we just did, to
// meet the marking overhead goal
double _marking_task_overhead; // marking target overhead for
// a single task
// same as the two above, but for the cleanup task
double _cleanup_sleep_factor;
double _cleanup_task_overhead;
FreeRegionList _cleanup_list;
// Concurrent marking support structures
CMBitMap _markBitMap1;
CMBitMap _markBitMap2;
CMBitMapRO* _prevMarkBitMap; // completed mark bitmap
CMBitMap* _nextMarkBitMap; // under-construction mark bitmap
BitMap _region_bm;
BitMap _card_bm;
// Heap bounds
HeapWord* _heap_start;
HeapWord* _heap_end;
// Root region tracking and claiming.
CMRootRegions _root_regions;
// For gray objects
CMMarkStack _markStack; // Grey objects behind global finger.
HeapWord* volatile _finger; // the global finger, region aligned,
// always points to the end of the
// last claimed region
// marking tasks
uint _max_worker_id;// maximum worker id
uint _active_tasks; // task num currently active
CMTask** _tasks; // task queue array (max_worker_id len)
CMTaskQueueSet* _task_queues; // task queue set
ParallelTaskTerminator _terminator; // for termination
// Two sync barriers that are used to synchronise tasks when an
// overflow occurs. The algorithm is the following. All tasks enter
// the first one to ensure that they have all stopped manipulating
// the global data structures. After they exit it, they re-initialise
// their data structures and task 0 re-initialises the global data
// structures. Then, they enter the second sync barrier. This
// ensure, that no task starts doing work before all data
// structures (local and global) have been re-initialised. When they
// exit it, they are free to start working again.
WorkGangBarrierSync _first_overflow_barrier_sync;
WorkGangBarrierSync _second_overflow_barrier_sync;
// this is set by any task, when an overflow on the global data
// structures is detected.
volatile bool _has_overflown;
// true: marking is concurrent, false: we're in remark
volatile bool _concurrent;
// set at the end of a Full GC so that marking aborts
volatile bool _has_aborted;
// used when remark aborts due to an overflow to indicate that
// another concurrent marking phase should start
volatile bool _restart_for_overflow;
// This is true from the very start of concurrent marking until the
// point when all the tasks complete their work. It is really used
// to determine the points between the end of concurrent marking and
// time of remark.
volatile bool _concurrent_marking_in_progress;
// verbose level
CMVerboseLevel _verbose_level;
// All of these times are in ms.
NumberSeq _init_times;
NumberSeq _remark_times;
NumberSeq _remark_mark_times;
NumberSeq _remark_weak_ref_times;
NumberSeq _cleanup_times;
double _total_counting_time;
double _total_rs_scrub_time;
double* _accum_task_vtime; // accumulated task vtime
FlexibleWorkGang* _parallel_workers;
ForceOverflowSettings _force_overflow_conc;
ForceOverflowSettings _force_overflow_stw;
void weakRefsWork(bool clear_all_soft_refs);
void swapMarkBitMaps();
// It resets the global marking data structures, as well as the
// task local ones; should be called during initial mark.
void reset();
// It resets all the marking data structures.
void clear_marking_state(bool clear_overflow = true);
// It should be called to indicate which phase we're in (concurrent
// mark or remark) and how many threads are currently active.
void set_phase(uint active_tasks, bool concurrent);
// We do this after we're done with marking so that the marking data
// structures are initialised to a sensible and predictable state.
void set_non_marking_state();
// prints all gathered CM-related statistics
void print_stats();
bool cleanup_list_is_empty() {
return _cleanup_list.is_empty();
}
// accessor methods
uint parallel_marking_threads() { return _parallel_marking_threads; }
uint max_parallel_marking_threads() { return _max_parallel_marking_threads;}
double sleep_factor() { return _sleep_factor; }
double marking_task_overhead() { return _marking_task_overhead;}
double cleanup_sleep_factor() { return _cleanup_sleep_factor; }
double cleanup_task_overhead() { return _cleanup_task_overhead;}
HeapWord* finger() { return _finger; }
bool concurrent() { return _concurrent; }
uint active_tasks() { return _active_tasks; }
ParallelTaskTerminator* terminator() { return &_terminator; }
// It claims the next available region to be scanned by a marking
// task/thread. It might return NULL if the next region is empty or
// we have run out of regions. In the latter case, out_of_regions()
// determines whether we've really run out of regions or the task
// should call claim_region() again. This might seem a bit
// awkward. Originally, the code was written so that claim_region()
// either successfully returned with a non-empty region or there
// were no more regions to be claimed. The problem with this was
// that, in certain circumstances, it iterated over large chunks of
// the heap finding only empty regions and, while it was working, it
// was preventing the calling task to call its regular clock
// method. So, this way, each task will spend very little time in
// claim_region() and is allowed to call the regular clock method
// frequently.
HeapRegion* claim_region(uint worker_id);
// It determines whether we've run out of regions to scan.
bool out_of_regions() { return _finger == _heap_end; }
// Returns the task with the given id
CMTask* task(int id) {
assert(0 <= id && id < (int) _active_tasks,
"task id not within active bounds");
return _tasks[id];
}
// Returns the task queue with the given id
CMTaskQueue* task_queue(int id) {
assert(0 <= id && id < (int) _active_tasks,
"task queue id not within active bounds");
return (CMTaskQueue*) _task_queues->queue(id);
}
// Returns the task queue set
CMTaskQueueSet* task_queues() { return _task_queues; }
// Access / manipulation of the overflow flag which is set to
// indicate that the global stack has overflown
bool has_overflown() { return _has_overflown; }
void set_has_overflown() { _has_overflown = true; }
void clear_has_overflown() { _has_overflown = false; }
bool restart_for_overflow() { return _restart_for_overflow; }
bool has_aborted() { return _has_aborted; }
// Methods to enter the two overflow sync barriers
void enter_first_sync_barrier(uint worker_id);
void enter_second_sync_barrier(uint worker_id);
ForceOverflowSettings* force_overflow_conc() {
return &_force_overflow_conc;
}
ForceOverflowSettings* force_overflow_stw() {
return &_force_overflow_stw;
}
ForceOverflowSettings* force_overflow() {
if (concurrent()) {
return force_overflow_conc();
} else {
return force_overflow_stw();
}
}
// Live Data Counting data structures...
// These data structures are initialized at the start of
// marking. They are written to while marking is active.
// They are aggregated during remark; the aggregated values
// are then used to populate the _region_bm, _card_bm, and
// the total live bytes, which are then subsequently updated
// during cleanup.
// An array of bitmaps (one bit map per task). Each bitmap
// is used to record the cards spanned by the live objects
// marked by that task/worker.
BitMap* _count_card_bitmaps;
// Used to record the number of marked live bytes
// (for each region, by worker thread).
size_t** _count_marked_bytes;
// Card index of the bottom of the G1 heap. Used for biasing indices into
// the card bitmaps.
intptr_t _heap_bottom_card_num;
public:
// Manipulation of the global mark stack.
// Notice that the first mark_stack_push is CAS-based, whereas the
// two below are Mutex-based. This is OK since the first one is only
// called during evacuation pauses and doesn't compete with the
// other two (which are called by the marking tasks during
// concurrent marking or remark).
bool mark_stack_push(oop p) {
_markStack.par_push(p);
if (_markStack.overflow()) {
set_has_overflown();
return false;
}
return true;
}
bool mark_stack_push(oop* arr, int n) {
_markStack.par_push_arr(arr, n);
if (_markStack.overflow()) {
set_has_overflown();
return false;
}
return true;
}
void mark_stack_pop(oop* arr, int max, int* n) {
_markStack.par_pop_arr(arr, max, n);
}
size_t mark_stack_size() { return _markStack.size(); }
size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
bool mark_stack_overflow() { return _markStack.overflow(); }
bool mark_stack_empty() { return _markStack.isEmpty(); }
CMRootRegions* root_regions() { return &_root_regions; }
bool concurrent_marking_in_progress() {
return _concurrent_marking_in_progress;
}
void set_concurrent_marking_in_progress() {
_concurrent_marking_in_progress = true;
}
void clear_concurrent_marking_in_progress() {
_concurrent_marking_in_progress = false;
}
void update_accum_task_vtime(int i, double vtime) {
_accum_task_vtime[i] += vtime;
}
double all_task_accum_vtime() {
double ret = 0.0;
for (uint i = 0; i < _max_worker_id; ++i)
ret += _accum_task_vtime[i];
return ret;
}
// Attempts to steal an object from the task queues of other tasks
bool try_stealing(uint worker_id, int* hash_seed, oop& obj) {
return _task_queues->steal(worker_id, hash_seed, obj);
}
ConcurrentMark(ReservedSpace rs, uint max_regions);
~ConcurrentMark();
ConcurrentMarkThread* cmThread() { return _cmThread; }
CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
// Returns the number of GC threads to be used in a concurrent
// phase based on the number of GC threads being used in a STW
// phase.
uint scale_parallel_threads(uint n_par_threads);
// Calculates the number of GC threads to be used in a concurrent phase.
uint calc_parallel_marking_threads();
// The following three are interaction between CM and
// G1CollectedHeap
// This notifies CM that a root during initial-mark needs to be
// grayed. It is MT-safe. word_size is the size of the object in
// words. It is passed explicitly as sometimes we cannot calculate
// it from the given object because it might be in an inconsistent
// state (e.g., in to-space and being copied). So the caller is
// responsible for dealing with this issue (e.g., get the size from
// the from-space image when the to-space image might be
// inconsistent) and always passing the size. hr is the region that
// contains the object and it's passed optionally from callers who
// might already have it (no point in recalculating it).
inline void grayRoot(oop obj, size_t word_size,
uint worker_id, HeapRegion* hr = NULL);
// It iterates over the heap and for each object it comes across it
// will dump the contents of its reference fields, as well as
// liveness information for the object and its referents. The dump
// will be written to a file with the following name:
// G1PrintReachableBaseFile + "." + str.
// vo decides whether the prev (vo == UsePrevMarking), the next
// (vo == UseNextMarking) marking information, or the mark word
// (vo == UseMarkWord) will be used to determine the liveness of
// each object / referent.
// If all is true, all objects in the heap will be dumped, otherwise
// only the live ones. In the dump the following symbols / breviations
// are used:
// M : an explicitly live object (its bitmap bit is set)
// > : an implicitly live object (over tams)
// O : an object outside the G1 heap (typically: in the perm gen)
// NOT : a reference field whose referent is not live
// AND MARKED : indicates that an object is both explicitly and
// implicitly live (it should be one or the other, not both)
void print_reachable(const char* str,
VerifyOption vo, bool all) PRODUCT_RETURN;
// Clear the next marking bitmap (will be called concurrently).
void clearNextBitmap();
// These two do the work that needs to be done before and after the
// initial root checkpoint. Since this checkpoint can be done at two
// different points (i.e. an explicit pause or piggy-backed on a
// young collection), then it's nice to be able to easily share the
// pre/post code. It might be the case that we can put everything in
// the post method. TP
void checkpointRootsInitialPre();
void checkpointRootsInitialPost();
// Scan all the root regions and mark everything reachable from
// them.
void scanRootRegions();
// Scan a single root region and mark everything reachable from it.
void scanRootRegion(HeapRegion* hr, uint worker_id);
// Do concurrent phase of marking, to a tentative transitive closure.
void markFromRoots();
void checkpointRootsFinal(bool clear_all_soft_refs);
void checkpointRootsFinalWork();
void cleanup();
void completeCleanup();
// Mark in the previous bitmap. NB: this is usually read-only, so use
// this carefully!
inline void markPrev(oop p);
// Clears marks for all objects in the given range, for the prev,
// next, or both bitmaps. NB: the previous bitmap is usually
// read-only, so use this carefully!
void clearRangePrevBitmap(MemRegion mr);
void clearRangeNextBitmap(MemRegion mr);
void clearRangeBothBitmaps(MemRegion mr);
// Notify data structures that a GC has started.
void note_start_of_gc() {
_markStack.note_start_of_gc();
}
// Notify data structures that a GC is finished.
void note_end_of_gc() {
_markStack.note_end_of_gc();
}
// Verify that there are no CSet oops on the stacks (taskqueues /
// global mark stack), enqueued SATB buffers, per-thread SATB
// buffers, and fingers (global / per-task). The boolean parameters
// decide which of the above data structures to verify. If marking
// is not in progress, it's a no-op.
void verify_no_cset_oops(bool verify_stacks,
bool verify_enqueued_buffers,
bool verify_thread_buffers,
bool verify_fingers) PRODUCT_RETURN;
// It is called at the end of an evacuation pause during marking so
// that CM is notified of where the new end of the heap is. It
// doesn't do anything if concurrent_marking_in_progress() is false,
// unless the force parameter is true.
void update_g1_committed(bool force = false);
bool isMarked(oop p) const {
assert(p != NULL && p->is_oop(), "expected an oop");
HeapWord* addr = (HeapWord*)p;
assert(addr >= _nextMarkBitMap->startWord() ||
addr < _nextMarkBitMap->endWord(), "in a region");
return _nextMarkBitMap->isMarked(addr);
}
inline bool not_yet_marked(oop p) const;
// XXX Debug code
bool containing_card_is_marked(void* p);
bool containing_cards_are_marked(void* start, void* last);
bool isPrevMarked(oop p) const {
assert(p != NULL && p->is_oop(), "expected an oop");
HeapWord* addr = (HeapWord*)p;
assert(addr >= _prevMarkBitMap->startWord() ||
addr < _prevMarkBitMap->endWord(), "in a region");
return _prevMarkBitMap->isMarked(addr);
}
inline bool do_yield_check(uint worker_i = 0);
inline bool should_yield();
// Called to abort the marking cycle after a Full GC takes palce.
void abort();
// This prints the global/local fingers. It is used for debugging.
NOT_PRODUCT(void print_finger();)
void print_summary_info();
void print_worker_threads_on(outputStream* st) const;
// The following indicate whether a given verbose level has been
// set. Notice that anything above stats is conditional to
// _MARKING_VERBOSE_ having been set to 1
bool verbose_stats() {
return _verbose_level >= stats_verbose;
}
bool verbose_low() {
return _MARKING_VERBOSE_ && _verbose_level >= low_verbose;
}
bool verbose_medium() {
return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose;
}
bool verbose_high() {
return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
}
// Liveness counting
// Utility routine to set an exclusive range of cards on the given
// card liveness bitmap
inline void set_card_bitmap_range(BitMap* card_bm,
BitMap::idx_t start_idx,
BitMap::idx_t end_idx,
bool is_par);
// Returns the card number of the bottom of the G1 heap.
// Used in biasing indices into accounting card bitmaps.
intptr_t heap_bottom_card_num() const {
return _heap_bottom_card_num;
}
// Returns the card bitmap for a given task or worker id.
BitMap* count_card_bitmap_for(uint worker_id) {
assert(0 <= worker_id && worker_id < _max_worker_id, "oob");
assert(_count_card_bitmaps != NULL, "uninitialized");
BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
return task_card_bm;
}
// Returns the array containing the marked bytes for each region,
// for the given worker or task id.
size_t* count_marked_bytes_array_for(uint worker_id) {
assert(0 <= worker_id && worker_id < _max_worker_id, "oob");
assert(_count_marked_bytes != NULL, "uninitialized");
size_t* marked_bytes_array = _count_marked_bytes[worker_id];
assert(marked_bytes_array != NULL, "uninitialized");
return marked_bytes_array;
}
// Returns the index in the liveness accounting card table bitmap
// for the given address
inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
// Counts the size of the given memory region in the the given
// marked_bytes array slot for the given HeapRegion.
// Sets the bits in the given card bitmap that are associated with the
// cards that are spanned by the memory region.
inline void count_region(MemRegion mr, HeapRegion* hr,
size_t* marked_bytes_array,
BitMap* task_card_bm);
// Counts the given memory region in the task/worker counting
// data structures for the given worker id.
inline void count_region(MemRegion mr, HeapRegion* hr, uint worker_id);
// Counts the given memory region in the task/worker counting
// data structures for the given worker id.
inline void count_region(MemRegion mr, uint worker_id);
// Counts the given object in the given task/worker counting
// data structures.
inline void count_object(oop obj, HeapRegion* hr,
size_t* marked_bytes_array,
BitMap* task_card_bm);
// Counts the given object in the task/worker counting data
// structures for the given worker id.
inline void count_object(oop obj, HeapRegion* hr, uint worker_id);
// Attempts to mark the given object and, if successful, counts
// the object in the given task/worker counting structures.
inline bool par_mark_and_count(oop obj, HeapRegion* hr,
size_t* marked_bytes_array,
BitMap* task_card_bm);
// Attempts to mark the given object and, if successful, counts
// the object in the task/worker counting structures for the
// given worker id.
inline bool par_mark_and_count(oop obj, size_t word_size,
HeapRegion* hr, uint worker_id);
// Attempts to mark the given object and, if successful, counts
// the object in the task/worker counting structures for the
// given worker id.
inline bool par_mark_and_count(oop obj, HeapRegion* hr, uint worker_id);
// Similar to the above routine but we don't know the heap region that
// contains the object to be marked/counted, which this routine looks up.
inline bool par_mark_and_count(oop obj, uint worker_id);
// Similar to the above routine but there are times when we cannot
// safely calculate the size of obj due to races and we, therefore,
// pass the size in as a parameter. It is the caller's reponsibility
// to ensure that the size passed in for obj is valid.
inline bool par_mark_and_count(oop obj, size_t word_size, uint worker_id);
// Unconditionally mark the given object, and unconditinally count
// the object in the counting structures for worker id 0.
// Should *not* be called from parallel code.
inline bool mark_and_count(oop obj, HeapRegion* hr);
// Similar to the above routine but we don't know the heap region that
// contains the object to be marked/counted, which this routine looks up.
// Should *not* be called from parallel code.
inline bool mark_and_count(oop obj);
protected:
// Clear all the per-task bitmaps and arrays used to store the
// counting data.
void clear_all_count_data();
// Aggregates the counting data for each worker/task
// that was constructed while marking. Also sets
// the amount of marked bytes for each region and
// the top at concurrent mark count.
void aggregate_count_data();
// Verification routine
void verify_count_data();
};
// A class representing a marking task.
class CMTask : public TerminatorTerminator {
private:
enum PrivateConstants {
// the regular clock call is called once the scanned words reaches
// this limit
words_scanned_period = 12*1024,
// the regular clock call is called once the number of visited
// references reaches this limit
refs_reached_period = 384,
// initial value for the hash seed, used in the work stealing code
init_hash_seed = 17,
// how many entries will be transferred between global stack and
// local queues
global_stack_transfer_size = 16
};
uint _worker_id;
G1CollectedHeap* _g1h;
ConcurrentMark* _cm;
CMBitMap* _nextMarkBitMap;
// the task queue of this task
CMTaskQueue* _task_queue;
private:
// the task queue set---needed for stealing
CMTaskQueueSet* _task_queues;
// indicates whether the task has been claimed---this is only for
// debugging purposes
bool _claimed;
// number of calls to this task
int _calls;
// when the virtual timer reaches this time, the marking step should
// exit
double _time_target_ms;
// the start time of the current marking step
double _start_time_ms;
// the oop closure used for iterations over oops
G1CMOopClosure* _cm_oop_closure;
// the region this task is scanning, NULL if we're not scanning any
HeapRegion* _curr_region;
// the local finger of this task, NULL if we're not scanning a region
HeapWord* _finger;
// limit of the region this task is scanning, NULL if we're not scanning one
HeapWord* _region_limit;
// the number of words this task has scanned
size_t _words_scanned;
// When _words_scanned reaches this limit, the regular clock is
// called. Notice that this might be decreased under certain
// circumstances (i.e. when we believe that we did an expensive
// operation).
size_t _words_scanned_limit;
// the initial value of _words_scanned_limit (i.e. what it was
// before it was decreased).
size_t _real_words_scanned_limit;
// the number of references this task has visited
size_t _refs_reached;
// When _refs_reached reaches this limit, the regular clock is
// called. Notice this this might be decreased under certain
// circumstances (i.e. when we believe that we did an expensive
// operation).
size_t _refs_reached_limit;
// the initial value of _refs_reached_limit (i.e. what it was before
// it was decreased).
size_t _real_refs_reached_limit;
// used by the work stealing stuff
int _hash_seed;
// if this is true, then the task has aborted for some reason
bool _has_aborted;
// set when the task aborts because it has met its time quota
bool _has_timed_out;
// true when we're draining SATB buffers; this avoids the task
// aborting due to SATB buffers being available (as we're already
// dealing with them)
bool _draining_satb_buffers;
// number sequence of past step times
NumberSeq _step_times_ms;
// elapsed time of this task
double _elapsed_time_ms;
// termination time of this task
double _termination_time_ms;
// when this task got into the termination protocol
double _termination_start_time_ms;
// true when the task is during a concurrent phase, false when it is
// in the remark phase (so, in the latter case, we do not have to
// check all the things that we have to check during the concurrent
// phase, i.e. SATB buffer availability...)
bool _concurrent;
TruncatedSeq _marking_step_diffs_ms;
// Counting data structures. Embedding the task's marked_bytes_array
// and card bitmap into the actual task saves having to go through
// the ConcurrentMark object.
size_t* _marked_bytes_array;
BitMap* _card_bm;
// LOTS of statistics related with this task
#if _MARKING_STATS_
NumberSeq _all_clock_intervals_ms;
double _interval_start_time_ms;
int _aborted;
int _aborted_overflow;
int _aborted_cm_aborted;
int _aborted_yield;
int _aborted_timed_out;
int _aborted_satb;
int _aborted_termination;
int _steal_attempts;
int _steals;
int _clock_due_to_marking;
int _clock_due_to_scanning;
int _local_pushes;
int _local_pops;
int _local_max_size;
int _objs_scanned;
int _global_pushes;
int _global_pops;
int _global_max_size;
int _global_transfers_to;
int _global_transfers_from;
int _regions_claimed;
int _objs_found_on_bitmap;
int _satb_buffers_processed;
#endif // _MARKING_STATS_
// it updates the local fields after this task has claimed
// a new region to scan
void setup_for_region(HeapRegion* hr);
// it brings up-to-date the limit of the region
void update_region_limit();
// called when either the words scanned or the refs visited limit
// has been reached
void reached_limit();
// recalculates the words scanned and refs visited limits
void recalculate_limits();
// decreases the words scanned and refs visited limits when we reach
// an expensive operation
void decrease_limits();
// it checks whether the words scanned or refs visited reached their
// respective limit and calls reached_limit() if they have
void check_limits() {
if (_words_scanned >= _words_scanned_limit ||
_refs_reached >= _refs_reached_limit) {
reached_limit();
}
}
// this is supposed to be called regularly during a marking step as
// it checks a bunch of conditions that might cause the marking step
// to abort
void regular_clock_call();
bool concurrent() { return _concurrent; }
public:
// It resets the task; it should be called right at the beginning of
// a marking phase.
void reset(CMBitMap* _nextMarkBitMap);
// it clears all the fields that correspond to a claimed region.
void clear_region_fields();
void set_concurrent(bool concurrent) { _concurrent = concurrent; }
// The main method of this class which performs a marking step
// trying not to exceed the given duration. However, it might exit
// prematurely, according to some conditions (i.e. SATB buffers are
// available for processing).
void do_marking_step(double target_ms, bool do_stealing, bool do_termination);
// These two calls start and stop the timer
void record_start_time() {
_elapsed_time_ms = os::elapsedTime() * 1000.0;
}
void record_end_time() {
_elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
}
// returns the worker ID associated with this task.
uint worker_id() { return _worker_id; }
// From TerminatorTerminator. It determines whether this task should
// exit the termination protocol after it's entered it.
virtual bool should_exit_termination();
// Resets the local region fields after a task has finished scanning a
// region; or when they have become stale as a result of the region
// being evacuated.
void giveup_current_region();
HeapWord* finger() { return _finger; }
bool has_aborted() { return _has_aborted; }
void set_has_aborted() { _has_aborted = true; }
void clear_has_aborted() { _has_aborted = false; }
bool has_timed_out() { return _has_timed_out; }
bool claimed() { return _claimed; }
void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
// It grays the object by marking it and, if necessary, pushing it
// on the local queue
inline void deal_with_reference(oop obj);
// It scans an object and visits its children.
void scan_object(oop obj);
// It pushes an object on the local queue.
inline void push(oop obj);
// These two move entries to/from the global stack.
void move_entries_to_global_stack();
void get_entries_from_global_stack();
// It pops and scans objects from the local queue. If partially is
// true, then it stops when the queue size is of a given limit. If
// partially is false, then it stops when the queue is empty.
void drain_local_queue(bool partially);
// It moves entries from the global stack to the local queue and
// drains the local queue. If partially is true, then it stops when
// both the global stack and the local queue reach a given size. If
// partially if false, it tries to empty them totally.
void drain_global_stack(bool partially);
// It keeps picking SATB buffers and processing them until no SATB
// buffers are available.
void drain_satb_buffers();
// moves the local finger to a new location
inline void move_finger_to(HeapWord* new_finger) {
assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
_finger = new_finger;
}
CMTask(uint worker_id, ConcurrentMark *cm,
size_t* marked_bytes, BitMap* card_bm,
CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
// it prints statistics associated with this task
void print_stats();
#if _MARKING_STATS_
void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
#endif // _MARKING_STATS_
};
// Class that's used to to print out per-region liveness
// information. It's currently used at the end of marking and also
// after we sort the old regions at the end of the cleanup operation.
class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
private:
outputStream* _out;
// Accumulators for these values.
size_t _total_used_bytes;
size_t _total_capacity_bytes;
size_t _total_prev_live_bytes;
size_t _total_next_live_bytes;
// These are set up when we come across a "stars humongous" region
// (as this is where most of this information is stored, not in the
// subsequent "continues humongous" regions). After that, for every
// region in a given humongous region series we deduce the right
// values for it by simply subtracting the appropriate amount from
// these fields. All these values should reach 0 after we've visited
// the last region in the series.
size_t _hum_used_bytes;
size_t _hum_capacity_bytes;
size_t _hum_prev_live_bytes;
size_t _hum_next_live_bytes;
static double perc(size_t val, size_t total) {
if (total == 0) {
return 0.0;
} else {
return 100.0 * ((double) val / (double) total);
}
}
static double bytes_to_mb(size_t val) {
return (double) val / (double) M;
}
// See the .cpp file.
size_t get_hum_bytes(size_t* hum_bytes);
void get_hum_bytes(size_t* used_bytes, size_t* capacity_bytes,
size_t* prev_live_bytes, size_t* next_live_bytes);
public:
// The header and footer are printed in the constructor and
// destructor respectively.
G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name);
virtual bool doHeapRegion(HeapRegion* r);
~G1PrintRegionLivenessInfoClosure();
};
#endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP