Java example source code file (g1RemSet.cpp)
The g1RemSet.cpp Java example source code
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
#include "precompiled.hpp"
#include "gc_implementation/g1/bufferingOopClosure.hpp"
#include "gc_implementation/g1/concurrentG1Refine.hpp"
#include "gc_implementation/g1/concurrentG1RefineThread.hpp"
#include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
#include "gc_implementation/g1/g1CollectorPolicy.hpp"
#include "gc_implementation/g1/g1HotCardCache.hpp"
#include "gc_implementation/g1/g1GCPhaseTimes.hpp"
#include "gc_implementation/g1/g1OopClosures.inline.hpp"
#include "gc_implementation/g1/g1RemSet.inline.hpp"
#include "gc_implementation/g1/heapRegionSeq.inline.hpp"
#include "gc_implementation/g1/heapRegionRemSet.hpp"
#include "memory/iterator.hpp"
#include "oops/oop.inline.hpp"
#include "utilities/intHisto.hpp"
#define CARD_REPEAT_HISTO 0
#if CARD_REPEAT_HISTO
static size_t ct_freq_sz;
static jbyte* ct_freq = NULL;
void init_ct_freq_table(size_t heap_sz_bytes) {
if (ct_freq == NULL) {
ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size;
ct_freq = new jbyte[ct_freq_sz];
for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0;
}
}
void ct_freq_note_card(size_t index) {
assert(0 <= index && index < ct_freq_sz, "Bounds error.");
if (ct_freq[index] < 100) { ct_freq[index]++; }
}
static IntHistogram card_repeat_count(10, 10);
void ct_freq_update_histo_and_reset() {
for (size_t j = 0; j < ct_freq_sz; j++) {
card_repeat_count.add_entry(ct_freq[j]);
ct_freq[j] = 0;
}
}
#endif
G1RemSet::G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs)
: _g1(g1), _conc_refine_cards(0),
_ct_bs(ct_bs), _g1p(_g1->g1_policy()),
_cg1r(g1->concurrent_g1_refine()),
_cset_rs_update_cl(NULL),
_cards_scanned(NULL), _total_cards_scanned(0),
_prev_period_summary()
{
_seq_task = new SubTasksDone(NumSeqTasks);
guarantee(n_workers() > 0, "There should be some workers");
_cset_rs_update_cl = NEW_C_HEAP_ARRAY(OopsInHeapRegionClosure*, n_workers(), mtGC);
for (uint i = 0; i < n_workers(); i++) {
_cset_rs_update_cl[i] = NULL;
}
if (G1SummarizeRSetStats) {
_prev_period_summary.initialize(this);
}
}
G1RemSet::~G1RemSet() {
delete _seq_task;
for (uint i = 0; i < n_workers(); i++) {
assert(_cset_rs_update_cl[i] == NULL, "it should be");
}
FREE_C_HEAP_ARRAY(OopsInHeapRegionClosure*, _cset_rs_update_cl, mtGC);
}
void CountNonCleanMemRegionClosure::do_MemRegion(MemRegion mr) {
if (_g1->is_in_g1_reserved(mr.start())) {
_n += (int) ((mr.byte_size() / CardTableModRefBS::card_size));
if (_start_first == NULL) _start_first = mr.start();
}
}
class ScanRSClosure : public HeapRegionClosure {
size_t _cards_done, _cards;
G1CollectedHeap* _g1h;
OopsInHeapRegionClosure* _oc;
CodeBlobToOopClosure* _code_root_cl;
G1BlockOffsetSharedArray* _bot_shared;
G1SATBCardTableModRefBS *_ct_bs;
double _strong_code_root_scan_time_sec;
int _worker_i;
int _block_size;
bool _try_claimed;
public:
ScanRSClosure(OopsInHeapRegionClosure* oc,
CodeBlobToOopClosure* code_root_cl,
int worker_i) :
_oc(oc),
_code_root_cl(code_root_cl),
_strong_code_root_scan_time_sec(0.0),
_cards(0),
_cards_done(0),
_worker_i(worker_i),
_try_claimed(false)
{
_g1h = G1CollectedHeap::heap();
_bot_shared = _g1h->bot_shared();
_ct_bs = _g1h->g1_barrier_set();
_block_size = MAX2<int>(G1RSetScanBlockSize, 1);
}
void set_try_claimed() { _try_claimed = true; }
void scanCard(size_t index, HeapRegion *r) {
// Stack allocate the DirtyCardToOopClosure instance
HeapRegionDCTOC cl(_g1h, r, _oc,
CardTableModRefBS::Precise,
HeapRegionDCTOC::IntoCSFilterKind);
// Set the "from" region in the closure.
_oc->set_region(r);
HeapWord* card_start = _bot_shared->address_for_index(index);
HeapWord* card_end = card_start + G1BlockOffsetSharedArray::N_words;
Space *sp = SharedHeap::heap()->space_containing(card_start);
MemRegion sm_region = sp->used_region_at_save_marks();
MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end));
if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) {
// We make the card as "claimed" lazily (so races are possible
// but they're benign), which reduces the number of duplicate
// scans (the rsets of the regions in the cset can intersect).
_ct_bs->set_card_claimed(index);
_cards_done++;
cl.do_MemRegion(mr);
}
}
void printCard(HeapRegion* card_region, size_t card_index,
HeapWord* card_start) {
gclog_or_tty->print_cr("T %d Region [" PTR_FORMAT ", " PTR_FORMAT ") "
"RS names card %p: "
"[" PTR_FORMAT ", " PTR_FORMAT ")",
_worker_i,
card_region->bottom(), card_region->end(),
card_index,
card_start, card_start + G1BlockOffsetSharedArray::N_words);
}
void scan_strong_code_roots(HeapRegion* r) {
double scan_start = os::elapsedTime();
r->strong_code_roots_do(_code_root_cl);
_strong_code_root_scan_time_sec += (os::elapsedTime() - scan_start);
}
bool doHeapRegion(HeapRegion* r) {
assert(r->in_collection_set(), "should only be called on elements of CS.");
HeapRegionRemSet* hrrs = r->rem_set();
if (hrrs->iter_is_complete()) return false; // All done.
if (!_try_claimed && !hrrs->claim_iter()) return false;
// If we ever free the collection set concurrently, we should also
// clear the card table concurrently therefore we won't need to
// add regions of the collection set to the dirty cards region.
_g1h->push_dirty_cards_region(r);
// If we didn't return above, then
// _try_claimed || r->claim_iter()
// is true: either we're supposed to work on claimed-but-not-complete
// regions, or we successfully claimed the region.
HeapRegionRemSetIterator iter(hrrs);
size_t card_index;
// We claim cards in block so as to recude the contention. The block size is determined by
// the G1RSetScanBlockSize parameter.
size_t jump_to_card = hrrs->iter_claimed_next(_block_size);
for (size_t current_card = 0; iter.has_next(card_index); current_card++) {
if (current_card >= jump_to_card + _block_size) {
jump_to_card = hrrs->iter_claimed_next(_block_size);
}
if (current_card < jump_to_card) continue;
HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index);
#if 0
gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n",
card_start, card_start + CardTableModRefBS::card_size_in_words);
#endif
HeapRegion* card_region = _g1h->heap_region_containing(card_start);
assert(card_region != NULL, "Yielding cards not in the heap?");
_cards++;
if (!card_region->is_on_dirty_cards_region_list()) {
_g1h->push_dirty_cards_region(card_region);
}
// If the card is dirty, then we will scan it during updateRS.
if (!card_region->in_collection_set() &&
!_ct_bs->is_card_dirty(card_index)) {
scanCard(card_index, card_region);
}
}
if (!_try_claimed) {
// Scan the strong code root list attached to the current region
scan_strong_code_roots(r);
hrrs->set_iter_complete();
}
return false;
}
double strong_code_root_scan_time_sec() {
return _strong_code_root_scan_time_sec;
}
size_t cards_done() { return _cards_done;}
size_t cards_looked_up() { return _cards;}
};
void G1RemSet::scanRS(OopsInHeapRegionClosure* oc,
CodeBlobToOopClosure* code_root_cl,
int worker_i) {
double rs_time_start = os::elapsedTime();
HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i);
ScanRSClosure scanRScl(oc, code_root_cl, worker_i);
_g1->collection_set_iterate_from(startRegion, &scanRScl);
scanRScl.set_try_claimed();
_g1->collection_set_iterate_from(startRegion, &scanRScl);
double scan_rs_time_sec = (os::elapsedTime() - rs_time_start)
- scanRScl.strong_code_root_scan_time_sec();
assert(_cards_scanned != NULL, "invariant");
_cards_scanned[worker_i] = scanRScl.cards_done();
_g1p->phase_times()->record_scan_rs_time(worker_i, scan_rs_time_sec * 1000.0);
_g1p->phase_times()->record_strong_code_root_scan_time(worker_i,
scanRScl.strong_code_root_scan_time_sec() * 1000.0);
}
// Closure used for updating RSets and recording references that
// point into the collection set. Only called during an
// evacuation pause.
class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
G1RemSet* _g1rs;
DirtyCardQueue* _into_cset_dcq;
public:
RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
DirtyCardQueue* into_cset_dcq) :
_g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
{}
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
// The only time we care about recording cards that
// contain references that point into the collection set
// is during RSet updating within an evacuation pause.
// In this case worker_i should be the id of a GC worker thread.
assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker");
if (_g1rs->refine_card(card_ptr, worker_i, true)) {
// 'card_ptr' contains references that point into the collection
// set. We need to record the card in the DCQS
// (G1CollectedHeap::into_cset_dirty_card_queue_set())
// that's used for that purpose.
//
// Enqueue the card
_into_cset_dcq->enqueue(card_ptr);
}
return true;
}
};
void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, int worker_i) {
double start = os::elapsedTime();
// Apply the given closure to all remaining log entries.
RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
_g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
// Now there should be no dirty cards.
if (G1RSLogCheckCardTable) {
CountNonCleanMemRegionClosure cl(_g1);
_ct_bs->mod_card_iterate(&cl);
// XXX This isn't true any more: keeping cards of young regions
// marked dirty broke it. Need some reasonable fix.
guarantee(cl.n() == 0, "Card table should be clean.");
}
_g1p->phase_times()->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0);
}
void G1RemSet::cleanupHRRS() {
HeapRegionRemSet::cleanup();
}
void G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
CodeBlobToOopClosure* code_root_cl,
int worker_i) {
#if CARD_REPEAT_HISTO
ct_freq_update_histo_and_reset();
#endif
// We cache the value of 'oc' closure into the appropriate slot in the
// _cset_rs_update_cl for this worker
assert(worker_i < (int)n_workers(), "sanity");
_cset_rs_update_cl[worker_i] = oc;
// A DirtyCardQueue that is used to hold cards containing references
// that point into the collection set. This DCQ is associated with a
// special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
// circumstances (i.e. the pause successfully completes), these cards
// are just discarded (there's no need to update the RSets of regions
// that were in the collection set - after the pause these regions
// are wholly 'free' of live objects. In the event of an evacuation
// failure the cards/buffers in this queue set are:
// * passed to the DirtyCardQueueSet that is used to manage deferred
// RSet updates, or
// * scanned for references that point into the collection set
// and the RSet of the corresponding region in the collection set
// is updated immediately.
DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
assert((ParallelGCThreads > 0) || worker_i == 0, "invariant");
// The two flags below were introduced temporarily to serialize
// the updating and scanning of remembered sets. There are some
// race conditions when these two operations are done in parallel
// and they are causing failures. When we resolve said race
// conditions, we'll revert back to parallel remembered set
// updating and scanning. See CRs 6677707 and 6677708.
if (G1UseParallelRSetUpdating || (worker_i == 0)) {
updateRS(&into_cset_dcq, worker_i);
} else {
_g1p->phase_times()->record_update_rs_processed_buffers(worker_i, 0);
_g1p->phase_times()->record_update_rs_time(worker_i, 0.0);
}
if (G1UseParallelRSetScanning || (worker_i == 0)) {
scanRS(oc, code_root_cl, worker_i);
} else {
_g1p->phase_times()->record_scan_rs_time(worker_i, 0.0);
}
// We now clear the cached values of _cset_rs_update_cl for this worker
_cset_rs_update_cl[worker_i] = NULL;
}
void G1RemSet::prepare_for_oops_into_collection_set_do() {
cleanupHRRS();
ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine();
_g1->set_refine_cte_cl_concurrency(false);
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
dcqs.concatenate_logs();
guarantee( _cards_scanned == NULL, "invariant" );
_cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers(), mtGC);
for (uint i = 0; i < n_workers(); ++i) {
_cards_scanned[i] = 0;
}
_total_cards_scanned = 0;
}
// This closure, applied to a DirtyCardQueueSet, is used to immediately
// update the RSets for the regions in the CSet. For each card it iterates
// through the oops which coincide with that card. It scans the reference
// fields in each oop; when it finds an oop that points into the collection
// set, the RSet for the region containing the referenced object is updated.
class UpdateRSetCardTableEntryIntoCSetClosure: public CardTableEntryClosure {
G1CollectedHeap* _g1;
CardTableModRefBS* _ct_bs;
public:
UpdateRSetCardTableEntryIntoCSetClosure(G1CollectedHeap* g1,
CardTableModRefBS* bs):
_g1(g1), _ct_bs(bs)
{ }
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
// Construct the region representing the card.
HeapWord* start = _ct_bs->addr_for(card_ptr);
// And find the region containing it.
HeapRegion* r = _g1->heap_region_containing(start);
assert(r != NULL, "unexpected null");
// Scan oops in the card looking for references into the collection set
// Don't use addr_for(card_ptr + 1) which can ask for
// a card beyond the heap. This is not safe without a perm
// gen.
HeapWord* end = start + CardTableModRefBS::card_size_in_words;
MemRegion scanRegion(start, end);
UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
// We can pass false as the "filter_young" parameter here as:
// * we should be in a STW pause,
// * the DCQS to which this closure is applied is used to hold
// references that point into the collection set from the prior
// RSet updating,
// * the post-write barrier shouldn't be logging updates to young
// regions (but there is a situation where this can happen - see
// the comment in G1RemSet::refine_card() below -
// that should not be applicable here), and
// * during actual RSet updating, the filtering of cards in young
// regions in HeapRegion::oops_on_card_seq_iterate_careful is
// employed.
// As a result, when this closure is applied to "refs into cset"
// DCQS, we shouldn't see any cards in young regions.
update_rs_cl.set_region(r);
HeapWord* stop_point =
r->oops_on_card_seq_iterate_careful(scanRegion,
&filter_then_update_rs_cset_oop_cl,
false /* filter_young */,
NULL /* card_ptr */);
// Since this is performed in the event of an evacuation failure, we
// we shouldn't see a non-null stop point
assert(stop_point == NULL, "saw an unallocated region");
return true;
}
};
void G1RemSet::cleanup_after_oops_into_collection_set_do() {
guarantee( _cards_scanned != NULL, "invariant" );
_total_cards_scanned = 0;
for (uint i = 0; i < n_workers(); ++i) {
_total_cards_scanned += _cards_scanned[i];
}
FREE_C_HEAP_ARRAY(size_t, _cards_scanned, mtGC);
_cards_scanned = NULL;
// Cleanup after copy
_g1->set_refine_cte_cl_concurrency(true);
// Set all cards back to clean.
_g1->cleanUpCardTable();
DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set();
int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num();
if (_g1->evacuation_failed()) {
// Restore remembered sets for the regions pointing into the collection set.
if (G1DeferredRSUpdate) {
// If deferred RS updates are enabled then we just need to transfer
// the completed buffers from (a) the DirtyCardQueueSet used to hold
// cards that contain references that point into the collection set
// to (b) the DCQS used to hold the deferred RS updates
_g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
} else {
CardTableModRefBS* bs = (CardTableModRefBS*)_g1->barrier_set();
UpdateRSetCardTableEntryIntoCSetClosure update_rs_cset_immediate(_g1, bs);
int n_completed_buffers = 0;
while (into_cset_dcqs.apply_closure_to_completed_buffer(&update_rs_cset_immediate,
0, 0, true)) {
n_completed_buffers++;
}
assert(n_completed_buffers == into_cset_n_buffers, "missed some buffers");
}
}
// Free any completed buffers in the DirtyCardQueueSet used to hold cards
// which contain references that point into the collection.
_g1->into_cset_dirty_card_queue_set().clear();
assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0,
"all buffers should be freed");
_g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers();
}
class ScrubRSClosure: public HeapRegionClosure {
G1CollectedHeap* _g1h;
BitMap* _region_bm;
BitMap* _card_bm;
CardTableModRefBS* _ctbs;
public:
ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) :
_g1h(G1CollectedHeap::heap()),
_region_bm(region_bm), _card_bm(card_bm),
_ctbs(_g1h->g1_barrier_set()) {}
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
}
return false;
}
};
void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
ScrubRSClosure scrub_cl(region_bm, card_bm);
_g1->heap_region_iterate(&scrub_cl);
}
void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
uint worker_num, int claim_val) {
ScrubRSClosure scrub_cl(region_bm, card_bm);
_g1->heap_region_par_iterate_chunked(&scrub_cl,
worker_num,
n_workers(),
claim_val);
}
G1TriggerClosure::G1TriggerClosure() :
_triggered(false) { }
G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
OopClosure* oop_cl) :
_trigger_cl(t_cl), _oop_cl(oop_cl) { }
G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
_c1(c1), _c2(c2) { }
G1UpdateRSOrPushRefOopClosure::
G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
G1RemSet* rs,
OopsInHeapRegionClosure* push_ref_cl,
bool record_refs_into_cset,
int worker_i) :
_g1(g1h), _g1_rem_set(rs), _from(NULL),
_record_refs_into_cset(record_refs_into_cset),
_push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
// Returns true if the given card contains references that point
// into the collection set, if we're checking for such references;
// false otherwise.
bool G1RemSet::refine_card(jbyte* card_ptr, int worker_i,
bool check_for_refs_into_cset) {
// If the card is no longer dirty, nothing to do.
if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
// No need to return that this card contains refs that point
// into the collection set.
return false;
}
// Construct the region representing the card.
HeapWord* start = _ct_bs->addr_for(card_ptr);
// And find the region containing it.
HeapRegion* r = _g1->heap_region_containing(start);
if (r == NULL) {
// Again no need to return that this card contains refs that
// point into the collection set.
return false; // Not in the G1 heap (might be in perm, for example.)
}
// Why do we have to check here whether a card is on a young region,
// given that we dirty young regions and, as a result, the
// post-barrier is supposed to filter them out and never to enqueue
// them? When we allocate a new region as the "allocation region" we
// actually dirty its cards after we release the lock, since card
// dirtying while holding the lock was a performance bottleneck. So,
// as a result, it is possible for other threads to actually
// allocate objects in the region (after the acquire the lock)
// before all the cards on the region are dirtied. This is unlikely,
// and it doesn't happen often, but it can happen. So, the extra
// check below filters out those cards.
if (r->is_young()) {
return false;
}
// While we are processing RSet buffers during the collection, we
// actually don't want to scan any cards on the collection set,
// since we don't want to update remebered sets with entries that
// point into the collection set, given that live objects from the
// collection set are about to move and such entries will be stale
// very soon. This change also deals with a reliability issue which
// involves scanning a card in the collection set and coming across
// an array that was being chunked and looking malformed. Note,
// however, that if evacuation fails, we have to scan any objects
// that were not moved and create any missing entries.
if (r->in_collection_set()) {
return false;
}
// The result from the hot card cache insert call is either:
// * pointer to the current card
// (implying that the current card is not 'hot'),
// * null
// (meaning we had inserted the card ptr into the "hot" card cache,
// which had some headroom),
// * a pointer to a "hot" card that was evicted from the "hot" cache.
//
G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
if (hot_card_cache->use_cache()) {
assert(!check_for_refs_into_cset, "sanity");
assert(!SafepointSynchronize::is_at_safepoint(), "sanity");
card_ptr = hot_card_cache->insert(card_ptr);
if (card_ptr == NULL) {
// There was no eviction. Nothing to do.
return false;
}
start = _ct_bs->addr_for(card_ptr);
r = _g1->heap_region_containing(start);
if (r == NULL) {
// Not in the G1 heap
return false;
}
// Checking whether the region we got back from the cache
// is young here is inappropriate. The region could have been
// freed, reallocated and tagged as young while in the cache.
// Hence we could see its young type change at any time.
}
// Don't use addr_for(card_ptr + 1) which can ask for
// a card beyond the heap. This is not safe without a perm
// gen at the upper end of the heap.
HeapWord* end = start + CardTableModRefBS::card_size_in_words;
MemRegion dirtyRegion(start, end);
#if CARD_REPEAT_HISTO
init_ct_freq_table(_g1->max_capacity());
ct_freq_note_card(_ct_bs->index_for(start));
#endif
OopsInHeapRegionClosure* oops_in_heap_closure = NULL;
if (check_for_refs_into_cset) {
// ConcurrentG1RefineThreads have worker numbers larger than what
// _cset_rs_update_cl[] is set up to handle. But those threads should
// only be active outside of a collection which means that when they
// reach here they should have check_for_refs_into_cset == false.
assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length");
oops_in_heap_closure = _cset_rs_update_cl[worker_i];
}
G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1,
_g1->g1_rem_set(),
oops_in_heap_closure,
check_for_refs_into_cset,
worker_i);
update_rs_oop_cl.set_from(r);
G1TriggerClosure trigger_cl;
FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl);
G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl);
G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl);
FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r,
(check_for_refs_into_cset ?
(OopClosure*)&mux :
(OopClosure*)&update_rs_oop_cl));
// The region for the current card may be a young region. The
// current card may have been a card that was evicted from the
// card cache. When the card was inserted into the cache, we had
// determined that its region was non-young. While in the cache,
// the region may have been freed during a cleanup pause, reallocated
// and tagged as young.
//
// We wish to filter out cards for such a region but the current
// thread, if we're running concurrently, may "see" the young type
// change at any time (so an earlier "is_young" check may pass or
// fail arbitrarily). We tell the iteration code to perform this
// filtering when it has been determined that there has been an actual
// allocation in this region and making it safe to check the young type.
bool filter_young = true;
HeapWord* stop_point =
r->oops_on_card_seq_iterate_careful(dirtyRegion,
&filter_then_update_rs_oop_cl,
filter_young,
card_ptr);
// If stop_point is non-null, then we encountered an unallocated region
// (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the
// card and re-enqueue: if we put off the card until a GC pause, then the
// unallocated portion will be filled in. Alternatively, we might try
// the full complexity of the technique used in "regular" precleaning.
if (stop_point != NULL) {
// The card might have gotten re-dirtied and re-enqueued while we
// worked. (In fact, it's pretty likely.)
if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
*card_ptr = CardTableModRefBS::dirty_card_val();
MutexLockerEx x(Shared_DirtyCardQ_lock,
Mutex::_no_safepoint_check_flag);
DirtyCardQueue* sdcq =
JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
sdcq->enqueue(card_ptr);
}
} else {
_conc_refine_cards++;
}
// This gets set to true if the card being refined has
// references that point into the collection set.
bool has_refs_into_cset = trigger_cl.triggered();
// We should only be detecting that the card contains references
// that point into the collection set if the current thread is
// a GC worker thread.
assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(),
"invalid result at non safepoint");
return has_refs_into_cset;
}
void G1RemSet::print_periodic_summary_info(const char* header) {
G1RemSetSummary current;
current.initialize(this);
_prev_period_summary.subtract_from(¤t);
print_summary_info(&_prev_period_summary, header);
_prev_period_summary.set(¤t);
}
void G1RemSet::print_summary_info() {
G1RemSetSummary current;
current.initialize(this);
print_summary_info(¤t, " Cumulative RS summary");
}
void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) {
assert(summary != NULL, "just checking");
if (header != NULL) {
gclog_or_tty->print_cr("%s", header);
}
#if CARD_REPEAT_HISTO
gclog_or_tty->print_cr("\nG1 card_repeat count histogram: ");
gclog_or_tty->print_cr(" # of repeats --> # of cards with that number.");
card_repeat_count.print_on(gclog_or_tty);
#endif
summary->print_on(gclog_or_tty);
}
void G1RemSet::prepare_for_verify() {
if (G1HRRSFlushLogBuffersOnVerify &&
(VerifyBeforeGC || VerifyAfterGC)
&& (!_g1->full_collection() || G1VerifyRSetsDuringFullGC)) {
cleanupHRRS();
_g1->set_refine_cte_cl_concurrency(false);
if (SafepointSynchronize::is_at_safepoint()) {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
dcqs.concatenate_logs();
}
G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
bool use_hot_card_cache = hot_card_cache->use_cache();
hot_card_cache->set_use_cache(false);
DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
updateRS(&into_cset_dcq, 0);
_g1->into_cset_dirty_card_queue_set().clear();
hot_card_cache->set_use_cache(use_hot_card_cache);
assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
}
}
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