6863216: Clean up debugging debris inadvertently pushed with 6700789
Summary: Anti-delta for debugging debris that was inadvertently pushed.
Reviewed-by: kvn, tonyp
/*
* Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
#include "incls/_precompiled.incl"
#include "incls/_g1CollectedHeap.cpp.incl"
// turn it on so that the contents of the young list (scan-only /
// to-be-collected) are printed at "strategic" points before / during
// / after the collection --- this is useful for debugging
#define SCAN_ONLY_VERBOSE 0
// CURRENT STATUS
// This file is under construction. Search for "FIXME".
// INVARIANTS/NOTES
//
// All allocation activity covered by the G1CollectedHeap interface is
// serialized by acquiring the HeapLock. This happens in
// mem_allocate_work, which all such allocation functions call.
// (Note that this does not apply to TLAB allocation, which is not part
// of this interface: it is done by clients of this interface.)
// Local to this file.
class RefineCardTableEntryClosure: public CardTableEntryClosure {
SuspendibleThreadSet* _sts;
G1RemSet* _g1rs;
ConcurrentG1Refine* _cg1r;
bool _concurrent;
public:
RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
G1RemSet* g1rs,
ConcurrentG1Refine* cg1r) :
_sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
{}
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
_g1rs->concurrentRefineOneCard(card_ptr, worker_i);
if (_concurrent && _sts->should_yield()) {
// Caller will actually yield.
return false;
}
// Otherwise, we finished successfully; return true.
return true;
}
void set_concurrent(bool b) { _concurrent = b; }
};
class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
int _calls;
G1CollectedHeap* _g1h;
CardTableModRefBS* _ctbs;
int _histo[256];
public:
ClearLoggedCardTableEntryClosure() :
_calls(0)
{
_g1h = G1CollectedHeap::heap();
_ctbs = (CardTableModRefBS*)_g1h->barrier_set();
for (int i = 0; i < 256; i++) _histo[i] = 0;
}
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
_calls++;
unsigned char* ujb = (unsigned char*)card_ptr;
int ind = (int)(*ujb);
_histo[ind]++;
*card_ptr = -1;
}
return true;
}
int calls() { return _calls; }
void print_histo() {
gclog_or_tty->print_cr("Card table value histogram:");
for (int i = 0; i < 256; i++) {
if (_histo[i] != 0) {
gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
}
}
}
};
class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
int _calls;
G1CollectedHeap* _g1h;
CardTableModRefBS* _ctbs;
public:
RedirtyLoggedCardTableEntryClosure() :
_calls(0)
{
_g1h = G1CollectedHeap::heap();
_ctbs = (CardTableModRefBS*)_g1h->barrier_set();
}
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
_calls++;
*card_ptr = 0;
}
return true;
}
int calls() { return _calls; }
};
class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
public:
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
*card_ptr = CardTableModRefBS::dirty_card_val();
return true;
}
};
YoungList::YoungList(G1CollectedHeap* g1h)
: _g1h(g1h), _head(NULL),
_scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
_length(0), _scan_only_length(0),
_last_sampled_rs_lengths(0),
_survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
{
guarantee( check_list_empty(false), "just making sure..." );
}
void YoungList::push_region(HeapRegion *hr) {
assert(!hr->is_young(), "should not already be young");
assert(hr->get_next_young_region() == NULL, "cause it should!");
hr->set_next_young_region(_head);
_head = hr;
hr->set_young();
double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
++_length;
}
void YoungList::add_survivor_region(HeapRegion* hr) {
assert(hr->is_survivor(), "should be flagged as survivor region");
assert(hr->get_next_young_region() == NULL, "cause it should!");
hr->set_next_young_region(_survivor_head);
if (_survivor_head == NULL) {
_survivor_tail = hr;
}
_survivor_head = hr;
++_survivor_length;
}
HeapRegion* YoungList::pop_region() {
while (_head != NULL) {
assert( length() > 0, "list should not be empty" );
HeapRegion* ret = _head;
_head = ret->get_next_young_region();
ret->set_next_young_region(NULL);
--_length;
assert(ret->is_young(), "region should be very young");
// Replace 'Survivor' region type with 'Young'. So the region will
// be treated as a young region and will not be 'confused' with
// newly created survivor regions.
if (ret->is_survivor()) {
ret->set_young();
}
if (!ret->is_scan_only()) {
return ret;
}
// scan-only, we'll add it to the scan-only list
if (_scan_only_tail == NULL) {
guarantee( _scan_only_head == NULL, "invariant" );
_scan_only_head = ret;
_curr_scan_only = ret;
} else {
guarantee( _scan_only_head != NULL, "invariant" );
_scan_only_tail->set_next_young_region(ret);
}
guarantee( ret->get_next_young_region() == NULL, "invariant" );
_scan_only_tail = ret;
// no need to be tagged as scan-only any more
ret->set_young();
++_scan_only_length;
}
assert( length() == 0, "list should be empty" );
return NULL;
}
void YoungList::empty_list(HeapRegion* list) {
while (list != NULL) {
HeapRegion* next = list->get_next_young_region();
list->set_next_young_region(NULL);
list->uninstall_surv_rate_group();
list->set_not_young();
list = next;
}
}
void YoungList::empty_list() {
assert(check_list_well_formed(), "young list should be well formed");
empty_list(_head);
_head = NULL;
_length = 0;
empty_list(_scan_only_head);
_scan_only_head = NULL;
_scan_only_tail = NULL;
_scan_only_length = 0;
_curr_scan_only = NULL;
empty_list(_survivor_head);
_survivor_head = NULL;
_survivor_tail = NULL;
_survivor_length = 0;
_last_sampled_rs_lengths = 0;
assert(check_list_empty(false), "just making sure...");
}
bool YoungList::check_list_well_formed() {
bool ret = true;
size_t length = 0;
HeapRegion* curr = _head;
HeapRegion* last = NULL;
while (curr != NULL) {
if (!curr->is_young() || curr->is_scan_only()) {
gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
"incorrectly tagged (%d, %d)",
curr->bottom(), curr->end(),
curr->is_young(), curr->is_scan_only());
ret = false;
}
++length;
last = curr;
curr = curr->get_next_young_region();
}
ret = ret && (length == _length);
if (!ret) {
gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
gclog_or_tty->print_cr("### list has %d entries, _length is %d",
length, _length);
}
bool scan_only_ret = true;
length = 0;
curr = _scan_only_head;
last = NULL;
while (curr != NULL) {
if (!curr->is_young() || curr->is_scan_only()) {
gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
"incorrectly tagged (%d, %d)",
curr->bottom(), curr->end(),
curr->is_young(), curr->is_scan_only());
scan_only_ret = false;
}
++length;
last = curr;
curr = curr->get_next_young_region();
}
scan_only_ret = scan_only_ret && (length == _scan_only_length);
if ( (last != _scan_only_tail) ||
(_scan_only_head == NULL && _scan_only_tail != NULL) ||
(_scan_only_head != NULL && _scan_only_tail == NULL) ) {
gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
scan_only_ret = false;
}
if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
scan_only_ret = false;
}
if (!scan_only_ret) {
gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
length, _scan_only_length);
}
return ret && scan_only_ret;
}
bool YoungList::check_list_empty(bool ignore_scan_only_list,
bool check_sample) {
bool ret = true;
if (_length != 0) {
gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
_length);
ret = false;
}
if (check_sample && _last_sampled_rs_lengths != 0) {
gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
ret = false;
}
if (_head != NULL) {
gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
ret = false;
}
if (!ret) {
gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
}
if (ignore_scan_only_list)
return ret;
bool scan_only_ret = true;
if (_scan_only_length != 0) {
gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
_scan_only_length);
scan_only_ret = false;
}
if (_scan_only_head != NULL) {
gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
scan_only_ret = false;
}
if (_scan_only_tail != NULL) {
gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
scan_only_ret = false;
}
if (!scan_only_ret) {
gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
}
return ret && scan_only_ret;
}
void
YoungList::rs_length_sampling_init() {
_sampled_rs_lengths = 0;
_curr = _head;
}
bool
YoungList::rs_length_sampling_more() {
return _curr != NULL;
}
void
YoungList::rs_length_sampling_next() {
assert( _curr != NULL, "invariant" );
_sampled_rs_lengths += _curr->rem_set()->occupied();
_curr = _curr->get_next_young_region();
if (_curr == NULL) {
_last_sampled_rs_lengths = _sampled_rs_lengths;
// gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
}
}
void
YoungList::reset_auxilary_lists() {
// We could have just "moved" the scan-only list to the young list.
// However, the scan-only list is ordered according to the region
// age in descending order, so, by moving one entry at a time, we
// ensure that it is recreated in ascending order.
guarantee( is_empty(), "young list should be empty" );
assert(check_list_well_formed(), "young list should be well formed");
// Add survivor regions to SurvRateGroup.
_g1h->g1_policy()->note_start_adding_survivor_regions();
_g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
for (HeapRegion* curr = _survivor_head;
curr != NULL;
curr = curr->get_next_young_region()) {
_g1h->g1_policy()->set_region_survivors(curr);
}
_g1h->g1_policy()->note_stop_adding_survivor_regions();
if (_survivor_head != NULL) {
_head = _survivor_head;
_length = _survivor_length + _scan_only_length;
_survivor_tail->set_next_young_region(_scan_only_head);
} else {
_head = _scan_only_head;
_length = _scan_only_length;
}
for (HeapRegion* curr = _scan_only_head;
curr != NULL;
curr = curr->get_next_young_region()) {
curr->recalculate_age_in_surv_rate_group();
}
_scan_only_head = NULL;
_scan_only_tail = NULL;
_scan_only_length = 0;
_curr_scan_only = NULL;
_survivor_head = NULL;
_survivor_tail = NULL;
_survivor_length = 0;
_g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
assert(check_list_well_formed(), "young list should be well formed");
}
void YoungList::print() {
HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
HeapRegion *curr = lists[list];
if (curr == NULL)
gclog_or_tty->print_cr(" empty");
while (curr != NULL) {
gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
"age: %4d, y: %d, s-o: %d, surv: %d",
curr->bottom(), curr->end(),
curr->top(),
curr->prev_top_at_mark_start(),
curr->next_top_at_mark_start(),
curr->top_at_conc_mark_count(),
curr->age_in_surv_rate_group_cond(),
curr->is_young(),
curr->is_scan_only(),
curr->is_survivor());
curr = curr->get_next_young_region();
}
}
gclog_or_tty->print_cr("");
}
void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
{
// Claim the right to put the region on the dirty cards region list
// by installing a self pointer.
HeapRegion* next = hr->get_next_dirty_cards_region();
if (next == NULL) {
HeapRegion* res = (HeapRegion*)
Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
NULL);
if (res == NULL) {
HeapRegion* head;
do {
// Put the region to the dirty cards region list.
head = _dirty_cards_region_list;
next = (HeapRegion*)
Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
if (next == head) {
assert(hr->get_next_dirty_cards_region() == hr,
"hr->get_next_dirty_cards_region() != hr");
if (next == NULL) {
// The last region in the list points to itself.
hr->set_next_dirty_cards_region(hr);
} else {
hr->set_next_dirty_cards_region(next);
}
}
} while (next != head);
}
}
}
HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
{
HeapRegion* head;
HeapRegion* hr;
do {
head = _dirty_cards_region_list;
if (head == NULL) {
return NULL;
}
HeapRegion* new_head = head->get_next_dirty_cards_region();
if (head == new_head) {
// The last region.
new_head = NULL;
}
hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
head);
} while (hr != head);
assert(hr != NULL, "invariant");
hr->set_next_dirty_cards_region(NULL);
return hr;
}
void G1CollectedHeap::stop_conc_gc_threads() {
_cg1r->stop();
_czft->stop();
_cmThread->stop();
}
void G1CollectedHeap::check_ct_logs_at_safepoint() {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
// Count the dirty cards at the start.
CountNonCleanMemRegionClosure count1(this);
ct_bs->mod_card_iterate(&count1);
int orig_count = count1.n();
// First clear the logged cards.
ClearLoggedCardTableEntryClosure clear;
dcqs.set_closure(&clear);
dcqs.apply_closure_to_all_completed_buffers();
dcqs.iterate_closure_all_threads(false);
clear.print_histo();
// Now ensure that there's no dirty cards.
CountNonCleanMemRegionClosure count2(this);
ct_bs->mod_card_iterate(&count2);
if (count2.n() != 0) {
gclog_or_tty->print_cr("Card table has %d entries; %d originally",
count2.n(), orig_count);
}
guarantee(count2.n() == 0, "Card table should be clean.");
RedirtyLoggedCardTableEntryClosure redirty;
JavaThread::dirty_card_queue_set().set_closure(&redirty);
dcqs.apply_closure_to_all_completed_buffers();
dcqs.iterate_closure_all_threads(false);
gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
clear.calls(), orig_count);
guarantee(redirty.calls() == clear.calls(),
"Or else mechanism is broken.");
CountNonCleanMemRegionClosure count3(this);
ct_bs->mod_card_iterate(&count3);
if (count3.n() != orig_count) {
gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
orig_count, count3.n());
guarantee(count3.n() >= orig_count, "Should have restored them all.");
}
JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
}
// Private class members.
G1CollectedHeap* G1CollectedHeap::_g1h;
// Private methods.
// Finds a HeapRegion that can be used to allocate a given size of block.
HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
bool do_expand,
bool zero_filled) {
ConcurrentZFThread::note_region_alloc();
HeapRegion* res = alloc_free_region_from_lists(zero_filled);
if (res == NULL && do_expand) {
expand(word_size * HeapWordSize);
res = alloc_free_region_from_lists(zero_filled);
assert(res == NULL ||
(!res->isHumongous() &&
(!zero_filled ||
res->zero_fill_state() == HeapRegion::Allocated)),
"Alloc Regions must be zero filled (and non-H)");
}
if (res != NULL && res->is_empty()) _free_regions--;
assert(res == NULL ||
(!res->isHumongous() &&
(!zero_filled ||
res->zero_fill_state() == HeapRegion::Allocated)),
"Non-young alloc Regions must be zero filled (and non-H)");
if (G1PrintRegions) {
if (res != NULL) {
gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
"top "PTR_FORMAT,
res->hrs_index(), res->bottom(), res->end(), res->top());
}
}
return res;
}
HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
size_t word_size,
bool zero_filled) {
HeapRegion* alloc_region = NULL;
if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
alloc_region = newAllocRegion_work(word_size, true, zero_filled);
if (purpose == GCAllocForSurvived && alloc_region != NULL) {
alloc_region->set_survivor();
}
++_gc_alloc_region_counts[purpose];
} else {
g1_policy()->note_alloc_region_limit_reached(purpose);
}
return alloc_region;
}
// If could fit into free regions w/o expansion, try.
// Otherwise, if can expand, do so.
// Otherwise, if using ex regions might help, try with ex given back.
HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
assert(regions_accounted_for(), "Region leakage!");
// We can't allocate H regions while cleanupComplete is running, since
// some of the regions we find to be empty might not yet be added to the
// unclean list. (If we're already at a safepoint, this call is
// unnecessary, not to mention wrong.)
if (!SafepointSynchronize::is_at_safepoint())
wait_for_cleanup_complete();
size_t num_regions =
round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
// Special case if < one region???
// Remember the ft size.
size_t x_size = expansion_regions();
HeapWord* res = NULL;
bool eliminated_allocated_from_lists = false;
// Can the allocation potentially fit in the free regions?
if (free_regions() >= num_regions) {
res = _hrs->obj_allocate(word_size);
}
if (res == NULL) {
// Try expansion.
size_t fs = _hrs->free_suffix();
if (fs + x_size >= num_regions) {
expand((num_regions - fs) * HeapRegion::GrainBytes);
res = _hrs->obj_allocate(word_size);
assert(res != NULL, "This should have worked.");
} else {
// Expansion won't help. Are there enough free regions if we get rid
// of reservations?
size_t avail = free_regions();
if (avail >= num_regions) {
res = _hrs->obj_allocate(word_size);
if (res != NULL) {
remove_allocated_regions_from_lists();
eliminated_allocated_from_lists = true;
}
}
}
}
if (res != NULL) {
// Increment by the number of regions allocated.
// FIXME: Assumes regions all of size GrainBytes.
#ifndef PRODUCT
mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
HeapRegion::GrainWords));
#endif
if (!eliminated_allocated_from_lists)
remove_allocated_regions_from_lists();
_summary_bytes_used += word_size * HeapWordSize;
_free_regions -= num_regions;
_num_humongous_regions += (int) num_regions;
}
assert(regions_accounted_for(), "Region Leakage");
return res;
}
HeapWord*
G1CollectedHeap::attempt_allocation_slow(size_t word_size,
bool permit_collection_pause) {
HeapWord* res = NULL;
HeapRegion* allocated_young_region = NULL;
assert( SafepointSynchronize::is_at_safepoint() ||
Heap_lock->owned_by_self(), "pre condition of the call" );
if (isHumongous(word_size)) {
// Allocation of a humongous object can, in a sense, complete a
// partial region, if the previous alloc was also humongous, and
// caused the test below to succeed.
if (permit_collection_pause)
do_collection_pause_if_appropriate(word_size);
res = humongousObjAllocate(word_size);
assert(_cur_alloc_region == NULL
|| !_cur_alloc_region->isHumongous(),
"Prevent a regression of this bug.");
} else {
// We may have concurrent cleanup working at the time. Wait for it
// to complete. In the future we would probably want to make the
// concurrent cleanup truly concurrent by decoupling it from the
// allocation.
if (!SafepointSynchronize::is_at_safepoint())
wait_for_cleanup_complete();
// If we do a collection pause, this will be reset to a non-NULL
// value. If we don't, nulling here ensures that we allocate a new
// region below.
if (_cur_alloc_region != NULL) {
// We're finished with the _cur_alloc_region.
_summary_bytes_used += _cur_alloc_region->used();
_cur_alloc_region = NULL;
}
assert(_cur_alloc_region == NULL, "Invariant.");
// Completion of a heap region is perhaps a good point at which to do
// a collection pause.
if (permit_collection_pause)
do_collection_pause_if_appropriate(word_size);
// Make sure we have an allocation region available.
if (_cur_alloc_region == NULL) {
if (!SafepointSynchronize::is_at_safepoint())
wait_for_cleanup_complete();
bool next_is_young = should_set_young_locked();
// If the next region is not young, make sure it's zero-filled.
_cur_alloc_region = newAllocRegion(word_size, !next_is_young);
if (_cur_alloc_region != NULL) {
_summary_bytes_used -= _cur_alloc_region->used();
if (next_is_young) {
set_region_short_lived_locked(_cur_alloc_region);
allocated_young_region = _cur_alloc_region;
}
}
}
assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
"Prevent a regression of this bug.");
// Now retry the allocation.
if (_cur_alloc_region != NULL) {
res = _cur_alloc_region->allocate(word_size);
}
}
// NOTE: fails frequently in PRT
assert(regions_accounted_for(), "Region leakage!");
if (res != NULL) {
if (!SafepointSynchronize::is_at_safepoint()) {
assert( permit_collection_pause, "invariant" );
assert( Heap_lock->owned_by_self(), "invariant" );
Heap_lock->unlock();
}
if (allocated_young_region != NULL) {
HeapRegion* hr = allocated_young_region;
HeapWord* bottom = hr->bottom();
HeapWord* end = hr->end();
MemRegion mr(bottom, end);
((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
}
}
assert( SafepointSynchronize::is_at_safepoint() ||
(res == NULL && Heap_lock->owned_by_self()) ||
(res != NULL && !Heap_lock->owned_by_self()),
"post condition of the call" );
return res;
}
HeapWord*
G1CollectedHeap::mem_allocate(size_t word_size,
bool is_noref,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded) {
debug_only(check_for_valid_allocation_state());
assert(no_gc_in_progress(), "Allocation during gc not allowed");
HeapWord* result = NULL;
// Loop until the allocation is satisified,
// or unsatisfied after GC.
for (int try_count = 1; /* return or throw */; try_count += 1) {
int gc_count_before;
{
Heap_lock->lock();
result = attempt_allocation(word_size);
if (result != NULL) {
// attempt_allocation should have unlocked the heap lock
assert(is_in(result), "result not in heap");
return result;
}
// Read the gc count while the heap lock is held.
gc_count_before = SharedHeap::heap()->total_collections();
Heap_lock->unlock();
}
// Create the garbage collection operation...
VM_G1CollectForAllocation op(word_size,
gc_count_before);
// ...and get the VM thread to execute it.
VMThread::execute(&op);
if (op.prologue_succeeded()) {
result = op.result();
assert(result == NULL || is_in(result), "result not in heap");
return result;
}
// Give a warning if we seem to be looping forever.
if ((QueuedAllocationWarningCount > 0) &&
(try_count % QueuedAllocationWarningCount == 0)) {
warning("G1CollectedHeap::mem_allocate_work retries %d times",
try_count);
}
}
}
void G1CollectedHeap::abandon_cur_alloc_region() {
if (_cur_alloc_region != NULL) {
// We're finished with the _cur_alloc_region.
if (_cur_alloc_region->is_empty()) {
_free_regions++;
free_region(_cur_alloc_region);
} else {
_summary_bytes_used += _cur_alloc_region->used();
}
_cur_alloc_region = NULL;
}
}
void G1CollectedHeap::abandon_gc_alloc_regions() {
// first, make sure that the GC alloc region list is empty (it should!)
assert(_gc_alloc_region_list == NULL, "invariant");
release_gc_alloc_regions(true /* totally */);
}
class PostMCRemSetClearClosure: public HeapRegionClosure {
ModRefBarrierSet* _mr_bs;
public:
PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
bool doHeapRegion(HeapRegion* r) {
r->reset_gc_time_stamp();
if (r->continuesHumongous())
return false;
HeapRegionRemSet* hrrs = r->rem_set();
if (hrrs != NULL) hrrs->clear();
// You might think here that we could clear just the cards
// corresponding to the used region. But no: if we leave a dirty card
// in a region we might allocate into, then it would prevent that card
// from being enqueued, and cause it to be missed.
// Re: the performance cost: we shouldn't be doing full GC anyway!
_mr_bs->clear(MemRegion(r->bottom(), r->end()));
return false;
}
};
class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
ModRefBarrierSet* _mr_bs;
public:
PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
bool doHeapRegion(HeapRegion* r) {
if (r->continuesHumongous()) return false;
if (r->used_region().word_size() != 0) {
_mr_bs->invalidate(r->used_region(), true /*whole heap*/);
}
return false;
}
};
class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
G1CollectedHeap* _g1h;
UpdateRSOopClosure _cl;
int _worker_i;
public:
RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
_cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
_worker_i(worker_i),
_g1h(g1)
{ }
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
_cl.set_from(r);
r->oop_iterate(&_cl);
}
return false;
}
};
class ParRebuildRSTask: public AbstractGangTask {
G1CollectedHeap* _g1;
public:
ParRebuildRSTask(G1CollectedHeap* g1)
: AbstractGangTask("ParRebuildRSTask"),
_g1(g1)
{ }
void work(int i) {
RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
_g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
HeapRegion::RebuildRSClaimValue);
}
};
void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
size_t word_size) {
ResourceMark rm;
if (PrintHeapAtGC) {
Universe::print_heap_before_gc();
}
if (full && DisableExplicitGC) {
gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
return;
}
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
if (GC_locker::is_active()) {
return; // GC is disabled (e.g. JNI GetXXXCritical operation)
}
{
IsGCActiveMark x;
// Timing
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
double start = os::elapsedTime();
GCOverheadReporter::recordSTWStart(start);
g1_policy()->record_full_collection_start();
gc_prologue(true);
increment_total_collections(true /* full gc */);
size_t g1h_prev_used = used();
assert(used() == recalculate_used(), "Should be equal");
if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
prepare_for_verify();
gclog_or_tty->print(" VerifyBeforeGC:");
Universe::verify(true);
}
assert(regions_accounted_for(), "Region leakage!");
COMPILER2_PRESENT(DerivedPointerTable::clear());
// We want to discover references, but not process them yet.
// This mode is disabled in
// instanceRefKlass::process_discovered_references if the
// generation does some collection work, or
// instanceRefKlass::enqueue_discovered_references if the
// generation returns without doing any work.
ref_processor()->disable_discovery();
ref_processor()->abandon_partial_discovery();
ref_processor()->verify_no_references_recorded();
// Abandon current iterations of concurrent marking and concurrent
// refinement, if any are in progress.
concurrent_mark()->abort();
// Make sure we'll choose a new allocation region afterwards.
abandon_cur_alloc_region();
abandon_gc_alloc_regions();
assert(_cur_alloc_region == NULL, "Invariant.");
g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
tear_down_region_lists();
set_used_regions_to_need_zero_fill();
if (g1_policy()->in_young_gc_mode()) {
empty_young_list();
g1_policy()->set_full_young_gcs(true);
}
// Temporarily make reference _discovery_ single threaded (non-MT).
ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
// Temporarily make refs discovery atomic
ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
// Temporarily clear _is_alive_non_header
ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
ref_processor()->enable_discovery();
ref_processor()->setup_policy(clear_all_soft_refs);
// Do collection work
{
HandleMark hm; // Discard invalid handles created during gc
G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
}
// Because freeing humongous regions may have added some unclean
// regions, it is necessary to tear down again before rebuilding.
tear_down_region_lists();
rebuild_region_lists();
_summary_bytes_used = recalculate_used();
ref_processor()->enqueue_discovered_references();
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
gclog_or_tty->print(" VerifyAfterGC:");
prepare_for_verify();
Universe::verify(false);
}
NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
reset_gc_time_stamp();
// Since everything potentially moved, we will clear all remembered
// sets, and clear all cards. Later we will rebuild remebered
// sets. We will also reset the GC time stamps of the regions.
PostMCRemSetClearClosure rs_clear(mr_bs());
heap_region_iterate(&rs_clear);
// Resize the heap if necessary.
resize_if_necessary_after_full_collection(full ? 0 : word_size);
if (_cg1r->use_cache()) {
_cg1r->clear_and_record_card_counts();
_cg1r->clear_hot_cache();
}
// Rebuild remembered sets of all regions.
if (ParallelGCThreads > 0) {
ParRebuildRSTask rebuild_rs_task(this);
assert(check_heap_region_claim_values(
HeapRegion::InitialClaimValue), "sanity check");
set_par_threads(workers()->total_workers());
workers()->run_task(&rebuild_rs_task);
set_par_threads(0);
assert(check_heap_region_claim_values(
HeapRegion::RebuildRSClaimValue), "sanity check");
reset_heap_region_claim_values();
} else {
RebuildRSOutOfRegionClosure rebuild_rs(this);
heap_region_iterate(&rebuild_rs);
}
if (PrintGC) {
print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
}
if (true) { // FIXME
// Ask the permanent generation to adjust size for full collections
perm()->compute_new_size();
}
double end = os::elapsedTime();
GCOverheadReporter::recordSTWEnd(end);
g1_policy()->record_full_collection_end();
#ifdef TRACESPINNING
ParallelTaskTerminator::print_termination_counts();
#endif
gc_epilogue(true);
// Discard all rset updates
JavaThread::dirty_card_queue_set().abandon_logs();
assert(!G1DeferredRSUpdate
|| (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
assert(regions_accounted_for(), "Region leakage!");
}
if (g1_policy()->in_young_gc_mode()) {
_young_list->reset_sampled_info();
assert( check_young_list_empty(false, false),
"young list should be empty at this point");
}
if (PrintHeapAtGC) {
Universe::print_heap_after_gc();
}
}
void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
do_collection(true, clear_all_soft_refs, 0);
}
// This code is mostly copied from TenuredGeneration.
void
G1CollectedHeap::
resize_if_necessary_after_full_collection(size_t word_size) {
assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
// Include the current allocation, if any, and bytes that will be
// pre-allocated to support collections, as "used".
const size_t used_after_gc = used();
const size_t capacity_after_gc = capacity();
const size_t free_after_gc = capacity_after_gc - used_after_gc;
// We don't have floating point command-line arguments
const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
const double maximum_used_percentage = 1.0 - minimum_free_percentage;
const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
const double minimum_used_percentage = 1.0 - maximum_free_percentage;
size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
// Don't shrink less than the initial size.
minimum_desired_capacity =
MAX2(minimum_desired_capacity,
collector_policy()->initial_heap_byte_size());
maximum_desired_capacity =
MAX2(maximum_desired_capacity,
collector_policy()->initial_heap_byte_size());
// We are failing here because minimum_desired_capacity is
assert(used_after_gc <= minimum_desired_capacity, "sanity check");
assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
if (PrintGC && Verbose) {
const double free_percentage = ((double)free_after_gc) / capacity();
gclog_or_tty->print_cr("Computing new size after full GC ");
gclog_or_tty->print_cr(" "
" minimum_free_percentage: %6.2f",
minimum_free_percentage);
gclog_or_tty->print_cr(" "
" maximum_free_percentage: %6.2f",
maximum_free_percentage);
gclog_or_tty->print_cr(" "
" capacity: %6.1fK"
" minimum_desired_capacity: %6.1fK"
" maximum_desired_capacity: %6.1fK",
capacity() / (double) K,
minimum_desired_capacity / (double) K,
maximum_desired_capacity / (double) K);
gclog_or_tty->print_cr(" "
" free_after_gc : %6.1fK"
" used_after_gc : %6.1fK",
free_after_gc / (double) K,
used_after_gc / (double) K);
gclog_or_tty->print_cr(" "
" free_percentage: %6.2f",
free_percentage);
}
if (capacity() < minimum_desired_capacity) {
// Don't expand unless it's significant
size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
expand(expand_bytes);
if (PrintGC && Verbose) {
gclog_or_tty->print_cr(" expanding:"
" minimum_desired_capacity: %6.1fK"
" expand_bytes: %6.1fK",
minimum_desired_capacity / (double) K,
expand_bytes / (double) K);
}
// No expansion, now see if we want to shrink
} else if (capacity() > maximum_desired_capacity) {
// Capacity too large, compute shrinking size
size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
shrink(shrink_bytes);
if (PrintGC && Verbose) {
gclog_or_tty->print_cr(" "
" shrinking:"
" initSize: %.1fK"
" maximum_desired_capacity: %.1fK",
collector_policy()->initial_heap_byte_size() / (double) K,
maximum_desired_capacity / (double) K);
gclog_or_tty->print_cr(" "
" shrink_bytes: %.1fK",
shrink_bytes / (double) K);
}
}
}
HeapWord*
G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
HeapWord* result = NULL;
// In a G1 heap, we're supposed to keep allocation from failing by
// incremental pauses. Therefore, at least for now, we'll favor
// expansion over collection. (This might change in the future if we can
// do something smarter than full collection to satisfy a failed alloc.)
result = expand_and_allocate(word_size);
if (result != NULL) {
assert(is_in(result), "result not in heap");
return result;
}
// OK, I guess we have to try collection.
do_collection(false, false, word_size);
result = attempt_allocation(word_size, /*permit_collection_pause*/false);
if (result != NULL) {
assert(is_in(result), "result not in heap");
return result;
}
// Try collecting soft references.
do_collection(false, true, word_size);
result = attempt_allocation(word_size, /*permit_collection_pause*/false);
if (result != NULL) {
assert(is_in(result), "result not in heap");
return result;
}
// What else? We might try synchronous finalization later. If the total
// space available is large enough for the allocation, then a more
// complete compaction phase than we've tried so far might be
// appropriate.
return NULL;
}
// 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* G1CollectedHeap::expand_and_allocate(size_t word_size) {
size_t expand_bytes = word_size * HeapWordSize;
if (expand_bytes < MinHeapDeltaBytes) {
expand_bytes = MinHeapDeltaBytes;
}
expand(expand_bytes);
assert(regions_accounted_for(), "Region leakage!");
HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
return result;
}
size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
size_t pre_used = 0;
size_t cleared_h_regions = 0;
size_t freed_regions = 0;
UncleanRegionList local_list;
free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
freed_regions, &local_list);
finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
&local_list);
return pre_used;
}
void
G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
size_t& pre_used,
size_t& cleared_h,
size_t& freed_regions,
UncleanRegionList* list,
bool par) {
assert(!hr->continuesHumongous(), "should have filtered these out");
size_t res = 0;
if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
!hr->is_young()) {
if (G1PolicyVerbose > 0)
gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
" during cleanup", hr, hr->used());
free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
}
}
// FIXME: both this and shrink could probably be more efficient by
// doing one "VirtualSpace::expand_by" call rather than several.
void G1CollectedHeap::expand(size_t expand_bytes) {
size_t old_mem_size = _g1_storage.committed_size();
// We expand by a minimum of 1K.
expand_bytes = MAX2(expand_bytes, (size_t)K);
size_t aligned_expand_bytes =
ReservedSpace::page_align_size_up(expand_bytes);
aligned_expand_bytes = align_size_up(aligned_expand_bytes,
HeapRegion::GrainBytes);
expand_bytes = aligned_expand_bytes;
while (expand_bytes > 0) {
HeapWord* base = (HeapWord*)_g1_storage.high();
// Commit more storage.
bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
if (!successful) {
expand_bytes = 0;
} else {
expand_bytes -= HeapRegion::GrainBytes;
// Expand the committed region.
HeapWord* high = (HeapWord*) _g1_storage.high();
_g1_committed.set_end(high);
// Create a new HeapRegion.
MemRegion mr(base, high);
bool is_zeroed = !_g1_max_committed.contains(base);
HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
// Now update max_committed if necessary.
_g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
// Add it to the HeapRegionSeq.
_hrs->insert(hr);
// Set the zero-fill state, according to whether it's already
// zeroed.
{
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
if (is_zeroed) {
hr->set_zero_fill_complete();
put_free_region_on_list_locked(hr);
} else {
hr->set_zero_fill_needed();
put_region_on_unclean_list_locked(hr);
}
}
_free_regions++;
// And we used up an expansion region to create it.
_expansion_regions--;
// Tell the cardtable about it.
Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
// And the offset table as well.
_bot_shared->resize(_g1_committed.word_size());
}
}
if (Verbose && PrintGC) {
size_t new_mem_size = _g1_storage.committed_size();
gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
old_mem_size/K, aligned_expand_bytes/K,
new_mem_size/K);
}
}
void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
{
size_t old_mem_size = _g1_storage.committed_size();
size_t aligned_shrink_bytes =
ReservedSpace::page_align_size_down(shrink_bytes);
aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
HeapRegion::GrainBytes);
size_t num_regions_deleted = 0;
MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
if (mr.byte_size() > 0)
_g1_storage.shrink_by(mr.byte_size());
assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
_g1_committed.set_end(mr.start());
_free_regions -= num_regions_deleted;
_expansion_regions += num_regions_deleted;
// Tell the cardtable about it.
Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
// And the offset table as well.
_bot_shared->resize(_g1_committed.word_size());
HeapRegionRemSet::shrink_heap(n_regions());
if (Verbose && PrintGC) {
size_t new_mem_size = _g1_storage.committed_size();
gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
old_mem_size/K, aligned_shrink_bytes/K,
new_mem_size/K);
}
}
void G1CollectedHeap::shrink(size_t shrink_bytes) {
release_gc_alloc_regions(true /* totally */);
tear_down_region_lists(); // We will rebuild them in a moment.
shrink_helper(shrink_bytes);
rebuild_region_lists();
}
// Public methods.
#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
#pragma warning( disable:4355 ) // 'this' : used in base member initializer list
#endif // _MSC_VER
G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
SharedHeap(policy_),
_g1_policy(policy_),
_ref_processor(NULL),
_process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
_bot_shared(NULL),
_par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
_objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
_evac_failure_scan_stack(NULL) ,
_mark_in_progress(false),
_cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
_cur_alloc_region(NULL),
_refine_cte_cl(NULL),
_free_region_list(NULL), _free_region_list_size(0),
_free_regions(0),
_full_collection(false),
_unclean_region_list(),
_unclean_regions_coming(false),
_young_list(new YoungList(this)),
_gc_time_stamp(0),
_surviving_young_words(NULL),
_in_cset_fast_test(NULL),
_in_cset_fast_test_base(NULL),
_dirty_cards_region_list(NULL) {
_g1h = this; // To catch bugs.
if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
vm_exit_during_initialization("Failed necessary allocation.");
}
int n_queues = MAX2((int)ParallelGCThreads, 1);
_task_queues = new RefToScanQueueSet(n_queues);
int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
assert(n_rem_sets > 0, "Invariant.");
HeapRegionRemSetIterator** iter_arr =
NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
for (int i = 0; i < n_queues; i++) {
iter_arr[i] = new HeapRegionRemSetIterator();
}
_rem_set_iterator = iter_arr;
for (int i = 0; i < n_queues; i++) {
RefToScanQueue* q = new RefToScanQueue();
q->initialize();
_task_queues->register_queue(i, q);
}
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
_gc_alloc_regions[ap] = NULL;
_gc_alloc_region_counts[ap] = 0;
_retained_gc_alloc_regions[ap] = NULL;
// by default, we do not retain a GC alloc region for each ap;
// we'll override this, when appropriate, below
_retain_gc_alloc_region[ap] = false;
}
// We will try to remember the last half-full tenured region we
// allocated to at the end of a collection so that we can re-use it
// during the next collection.
_retain_gc_alloc_region[GCAllocForTenured] = true;
guarantee(_task_queues != NULL, "task_queues allocation failure.");
}
jint G1CollectedHeap::initialize() {
os::enable_vtime();
// Necessary to satisfy locking discipline assertions.
MutexLocker x(Heap_lock);
// While there are no constraints in the GC code that HeapWordSize
// be any particular value, there are multiple other areas in the
// system which believe this to be true (e.g. oop->object_size in some
// cases incorrectly returns the size in wordSize units rather than
// HeapWordSize).
guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
size_t init_byte_size = collector_policy()->initial_heap_byte_size();
size_t max_byte_size = collector_policy()->max_heap_byte_size();
// Ensure that the sizes are properly aligned.
Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
// We allocate this in any case, but only do no work if the command line
// param is off.
_cg1r = new ConcurrentG1Refine();
// Reserve the maximum.
PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
// Includes the perm-gen.
const size_t total_reserved = max_byte_size + pgs->max_size();
char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
HeapRegion::GrainBytes,
false /*ism*/, addr);
if (UseCompressedOops) {
if (addr != NULL && !heap_rs.is_reserved()) {
// Failed to reserve at specified address - the requested memory
// region is taken already, for example, by 'java' launcher.
// Try again to reserver heap higher.
addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
false /*ism*/, addr);
if (addr != NULL && !heap_rs0.is_reserved()) {
// Failed to reserve at specified address again - give up.
addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
assert(addr == NULL, "");
ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
false /*ism*/, addr);
heap_rs = heap_rs1;
} else {
heap_rs = heap_rs0;
}
}
}
if (!heap_rs.is_reserved()) {
vm_exit_during_initialization("Could not reserve enough space for object heap");
return JNI_ENOMEM;
}
// It is important to do this in a way such that concurrent readers can't
// temporarily think somethings in the heap. (I've actually seen this
// happen in asserts: DLD.)
_reserved.set_word_size(0);
_reserved.set_start((HeapWord*)heap_rs.base());
_reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
_expansion_regions = max_byte_size/HeapRegion::GrainBytes;
_num_humongous_regions = 0;
// Create the gen rem set (and barrier set) for the entire reserved region.
_rem_set = collector_policy()->create_rem_set(_reserved, 2);
set_barrier_set(rem_set()->bs());
if (barrier_set()->is_a(BarrierSet::ModRef)) {
_mr_bs = (ModRefBarrierSet*)_barrier_set;
} else {
vm_exit_during_initialization("G1 requires a mod ref bs.");
return JNI_ENOMEM;
}
// Also create a G1 rem set.
if (G1UseHRIntoRS) {
if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
_g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
} else {
vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
return JNI_ENOMEM;
}
} else {
_g1_rem_set = new StupidG1RemSet(this);
}
// Carve out the G1 part of the heap.
ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
_g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
g1_rs.size()/HeapWordSize);
ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
_perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
_g1_storage.initialize(g1_rs, 0);
_g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
_g1_max_committed = _g1_committed;
_hrs = new HeapRegionSeq(_expansion_regions);
guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
guarantee(_cur_alloc_region == NULL, "from constructor");
// 6843694 - ensure that the maximum region index can fit
// in the remembered set structures.
const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
const size_t cards_per_region = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift;
size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
guarantee(cards_per_region < max_cards_per_region, "too many cards per region");
_bot_shared = new G1BlockOffsetSharedArray(_reserved,
heap_word_size(init_byte_size));
_g1h = this;
// Create the ConcurrentMark data structure and thread.
// (Must do this late, so that "max_regions" is defined.)
_cm = new ConcurrentMark(heap_rs, (int) max_regions());
_cmThread = _cm->cmThread();
// ...and the concurrent zero-fill thread, if necessary.
if (G1ConcZeroFill) {
_czft = new ConcurrentZFThread();
}
// Initialize the from_card cache structure of HeapRegionRemSet.
HeapRegionRemSet::init_heap(max_regions());
// Now expand into the initial heap size.
expand(init_byte_size);
// Perform any initialization actions delegated to the policy.
g1_policy()->init();
g1_policy()->note_start_of_mark_thread();
_refine_cte_cl =
new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
g1_rem_set(),
concurrent_g1_refine());
JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
SATB_Q_FL_lock,
0,
Shared_SATB_Q_lock);
JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
DirtyCardQ_FL_lock,
G1DirtyCardQueueMax,
Shared_DirtyCardQ_lock);
if (G1DeferredRSUpdate) {
dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
DirtyCardQ_FL_lock,
0,
Shared_DirtyCardQ_lock,
&JavaThread::dirty_card_queue_set());
}
// In case we're keeping closure specialization stats, initialize those
// counts and that mechanism.
SpecializationStats::clear();
_gc_alloc_region_list = NULL;
// Do later initialization work for concurrent refinement.
_cg1r->init();
const char* group_names[] = { "CR", "ZF", "CM", "CL" };
GCOverheadReporter::initGCOverheadReporter(4, group_names);
return JNI_OK;
}
void G1CollectedHeap::ref_processing_init() {
SharedHeap::ref_processing_init();
MemRegion mr = reserved_region();
_ref_processor = ReferenceProcessor::create_ref_processor(
mr, // span
false, // Reference discovery is not atomic
// (though it shouldn't matter here.)
true, // mt_discovery
NULL, // is alive closure: need to fill this in for efficiency
ParallelGCThreads,
ParallelRefProcEnabled,
true); // Setting next fields of discovered
// lists requires a barrier.
}
size_t G1CollectedHeap::capacity() const {
return _g1_committed.byte_size();
}
void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
int worker_i) {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
int n_completed_buffers = 0;
while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
n_completed_buffers++;
}
g1_policy()->record_update_rs_processed_buffers(worker_i,
(double) n_completed_buffers);
dcqs.clear_n_completed_buffers();
// Finish up the queue...
if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
g1_rem_set());
assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
}
// Computes the sum of the storage used by the various regions.
size_t G1CollectedHeap::used() const {
assert(Heap_lock->owner() != NULL,
"Should be owned on this thread's behalf.");
size_t result = _summary_bytes_used;
// Read only once in case it is set to NULL concurrently
HeapRegion* hr = _cur_alloc_region;
if (hr != NULL)
result += hr->used();
return result;
}
size_t G1CollectedHeap::used_unlocked() const {
size_t result = _summary_bytes_used;
return result;
}
class SumUsedClosure: public HeapRegionClosure {
size_t _used;
public:
SumUsedClosure() : _used(0) {}
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
_used += r->used();
}
return false;
}
size_t result() { return _used; }
};
size_t G1CollectedHeap::recalculate_used() const {
SumUsedClosure blk;
_hrs->iterate(&blk);
return blk.result();
}
#ifndef PRODUCT
class SumUsedRegionsClosure: public HeapRegionClosure {
size_t _num;
public:
SumUsedRegionsClosure() : _num(0) {}
bool doHeapRegion(HeapRegion* r) {
if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
_num += 1;
}
return false;
}
size_t result() { return _num; }
};
size_t G1CollectedHeap::recalculate_used_regions() const {
SumUsedRegionsClosure blk;
_hrs->iterate(&blk);
return blk.result();
}
#endif // PRODUCT
size_t G1CollectedHeap::unsafe_max_alloc() {
if (_free_regions > 0) return HeapRegion::GrainBytes;
// otherwise, is there space in the current allocation region?
// We need to store the current allocation region in a local variable
// here. The problem is that this method doesn't take any locks and
// there may be other threads which overwrite the current allocation
// region field. attempt_allocation(), for example, sets it to NULL
// and this can happen *after* the NULL check here but before the call
// to free(), resulting in a SIGSEGV. Note that this doesn't appear
// to be a problem in the optimized build, since the two loads of the
// current allocation region field are optimized away.
HeapRegion* car = _cur_alloc_region;
// FIXME: should iterate over all regions?
if (car == NULL) {
return 0;
}
return car->free();
}
void G1CollectedHeap::collect(GCCause::Cause cause) {
// The caller doesn't have the Heap_lock
assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
MutexLocker ml(Heap_lock);
collect_locked(cause);
}
void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
assert(Thread::current()->is_VM_thread(), "Precondition#1");
assert(Heap_lock->is_locked(), "Precondition#2");
GCCauseSetter gcs(this, cause);
switch (cause) {
case GCCause::_heap_inspection:
case GCCause::_heap_dump: {
HandleMark hm;
do_full_collection(false); // don't clear all soft refs
break;
}
default: // XXX FIX ME
ShouldNotReachHere(); // Unexpected use of this function
}
}
void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
// Don't want to do a GC until cleanup is completed.
wait_for_cleanup_complete();
// Read the GC count while holding the Heap_lock
int gc_count_before = SharedHeap::heap()->total_collections();
{
MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
VM_G1CollectFull op(gc_count_before, cause);
VMThread::execute(&op);
}
}
bool G1CollectedHeap::is_in(const void* p) const {
if (_g1_committed.contains(p)) {
HeapRegion* hr = _hrs->addr_to_region(p);
return hr->is_in(p);
} else {
return _perm_gen->as_gen()->is_in(p);
}
}
// Iteration functions.
// Iterates an OopClosure over all ref-containing fields of objects
// within a HeapRegion.
class IterateOopClosureRegionClosure: public HeapRegionClosure {
MemRegion _mr;
OopClosure* _cl;
public:
IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
: _mr(mr), _cl(cl) {}
bool doHeapRegion(HeapRegion* r) {
if (! r->continuesHumongous()) {
r->oop_iterate(_cl);
}
return false;
}
};
void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
IterateOopClosureRegionClosure blk(_g1_committed, cl);
_hrs->iterate(&blk);
if (do_perm) {
perm_gen()->oop_iterate(cl);
}
}
void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
IterateOopClosureRegionClosure blk(mr, cl);
_hrs->iterate(&blk);
if (do_perm) {
perm_gen()->oop_iterate(cl);
}
}
// Iterates an ObjectClosure over all objects within a HeapRegion.
class IterateObjectClosureRegionClosure: public HeapRegionClosure {
ObjectClosure* _cl;
public:
IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
bool doHeapRegion(HeapRegion* r) {
if (! r->continuesHumongous()) {
r->object_iterate(_cl);
}
return false;
}
};
void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
IterateObjectClosureRegionClosure blk(cl);
_hrs->iterate(&blk);
if (do_perm) {
perm_gen()->object_iterate(cl);
}
}
void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
// FIXME: is this right?
guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
}
// Calls a SpaceClosure on a HeapRegion.
class SpaceClosureRegionClosure: public HeapRegionClosure {
SpaceClosure* _cl;
public:
SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
bool doHeapRegion(HeapRegion* r) {
_cl->do_space(r);
return false;
}
};
void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
SpaceClosureRegionClosure blk(cl);
_hrs->iterate(&blk);
}
void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
_hrs->iterate(cl);
}
void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
HeapRegionClosure* cl) {
_hrs->iterate_from(r, cl);
}
void
G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
_hrs->iterate_from(idx, cl);
}
HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
void
G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
int worker,
jint claim_value) {
const size_t regions = n_regions();
const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
// try to spread out the starting points of the workers
const size_t start_index = regions / worker_num * (size_t) worker;
// each worker will actually look at all regions
for (size_t count = 0; count < regions; ++count) {
const size_t index = (start_index + count) % regions;
assert(0 <= index && index < regions, "sanity");
HeapRegion* r = region_at(index);
// we'll ignore "continues humongous" regions (we'll process them
// when we come across their corresponding "start humongous"
// region) and regions already claimed
if (r->claim_value() == claim_value || r->continuesHumongous()) {
continue;
}
// OK, try to claim it
if (r->claimHeapRegion(claim_value)) {
// success!
assert(!r->continuesHumongous(), "sanity");
if (r->startsHumongous()) {
// If the region is "starts humongous" we'll iterate over its
// "continues humongous" first; in fact we'll do them
// first. The order is important. In on case, calling the
// closure on the "starts humongous" region might de-allocate
// and clear all its "continues humongous" regions and, as a
// result, we might end up processing them twice. So, we'll do
// them first (notice: most closures will ignore them anyway) and
// then we'll do the "starts humongous" region.
for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
HeapRegion* chr = region_at(ch_index);
// if the region has already been claimed or it's not
// "continues humongous" we're done
if (chr->claim_value() == claim_value ||
!chr->continuesHumongous()) {
break;
}
// Noone should have claimed it directly. We can given
// that we claimed its "starts humongous" region.
assert(chr->claim_value() != claim_value, "sanity");
assert(chr->humongous_start_region() == r, "sanity");
if (chr->claimHeapRegion(claim_value)) {
// we should always be able to claim it; noone else should
// be trying to claim this region
bool res2 = cl->doHeapRegion(chr);
assert(!res2, "Should not abort");
// Right now, this holds (i.e., no closure that actually
// does something with "continues humongous" regions
// clears them). We might have to weaken it in the future,
// but let's leave these two asserts here for extra safety.
assert(chr->continuesHumongous(), "should still be the case");
assert(chr->humongous_start_region() == r, "sanity");
} else {
guarantee(false, "we should not reach here");
}
}
}
assert(!r->continuesHumongous(), "sanity");
bool res = cl->doHeapRegion(r);
assert(!res, "Should not abort");
}
}
}
class ResetClaimValuesClosure: public HeapRegionClosure {
public:
bool doHeapRegion(HeapRegion* r) {
r->set_claim_value(HeapRegion::InitialClaimValue);
return false;
}
};
void
G1CollectedHeap::reset_heap_region_claim_values() {
ResetClaimValuesClosure blk;
heap_region_iterate(&blk);
}
#ifdef ASSERT
// This checks whether all regions in the heap have the correct claim
// value. I also piggy-backed on this a check to ensure that the
// humongous_start_region() information on "continues humongous"
// regions is correct.
class CheckClaimValuesClosure : public HeapRegionClosure {
private:
jint _claim_value;
size_t _failures;
HeapRegion* _sh_region;
public:
CheckClaimValuesClosure(jint claim_value) :
_claim_value(claim_value), _failures(0), _sh_region(NULL) { }
bool doHeapRegion(HeapRegion* r) {
if (r->claim_value() != _claim_value) {
gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
"claim value = %d, should be %d",
r->bottom(), r->end(), r->claim_value(),
_claim_value);
++_failures;
}
if (!r->isHumongous()) {
_sh_region = NULL;
} else if (r->startsHumongous()) {
_sh_region = r;
} else if (r->continuesHumongous()) {
if (r->humongous_start_region() != _sh_region) {
gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
"HS = "PTR_FORMAT", should be "PTR_FORMAT,
r->bottom(), r->end(),
r->humongous_start_region(),
_sh_region);
++_failures;
}
}
return false;
}
size_t failures() {
return _failures;
}
};
bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
CheckClaimValuesClosure cl(claim_value);
heap_region_iterate(&cl);
return cl.failures() == 0;
}
#endif // ASSERT
void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
HeapRegion* r = g1_policy()->collection_set();
while (r != NULL) {
HeapRegion* next = r->next_in_collection_set();
if (cl->doHeapRegion(r)) {
cl->incomplete();
return;
}
r = next;
}
}
void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
HeapRegionClosure *cl) {
assert(r->in_collection_set(),
"Start region must be a member of the collection set.");
HeapRegion* cur = r;
while (cur != NULL) {
HeapRegion* next = cur->next_in_collection_set();
if (cl->doHeapRegion(cur) && false) {
cl->incomplete();
return;
}
cur = next;
}
cur = g1_policy()->collection_set();
while (cur != r) {
HeapRegion* next = cur->next_in_collection_set();
if (cl->doHeapRegion(cur) && false) {
cl->incomplete();
return;
}
cur = next;
}
}
CompactibleSpace* G1CollectedHeap::first_compactible_space() {
return _hrs->length() > 0 ? _hrs->at(0) : NULL;
}
Space* G1CollectedHeap::space_containing(const void* addr) const {
Space* res = heap_region_containing(addr);
if (res == NULL)
res = perm_gen()->space_containing(addr);
return res;
}
HeapWord* G1CollectedHeap::block_start(const void* addr) const {
Space* sp = space_containing(addr);
if (sp != NULL) {
return sp->block_start(addr);
}
return NULL;
}
size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
Space* sp = space_containing(addr);
assert(sp != NULL, "block_size of address outside of heap");
return sp->block_size(addr);
}
bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
Space* sp = space_containing(addr);
return sp->block_is_obj(addr);
}
bool G1CollectedHeap::supports_tlab_allocation() const {
return true;
}
size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
return HeapRegion::GrainBytes;
}
size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
// Return the remaining space in the cur alloc region, but not less than
// the min TLAB size.
// Also, no more than half the region size, since we can't allow tlabs to
// grow big enough to accomodate humongous objects.
// We need to story it locally, since it might change between when we
// test for NULL and when we use it later.
ContiguousSpace* cur_alloc_space = _cur_alloc_region;
if (cur_alloc_space == NULL) {
return HeapRegion::GrainBytes/2;
} else {
return MAX2(MIN2(cur_alloc_space->free(),
(size_t)(HeapRegion::GrainBytes/2)),
(size_t)MinTLABSize);
}
}
HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
bool dummy;
return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
}
bool G1CollectedHeap::allocs_are_zero_filled() {
return false;
}
size_t G1CollectedHeap::large_typearray_limit() {
// FIXME
return HeapRegion::GrainBytes/HeapWordSize;
}
size_t G1CollectedHeap::max_capacity() const {
return _g1_committed.byte_size();
}
jlong G1CollectedHeap::millis_since_last_gc() {
// assert(false, "NYI");
return 0;
}
void G1CollectedHeap::prepare_for_verify() {
if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
ensure_parsability(false);
}
g1_rem_set()->prepare_for_verify();
}
class VerifyLivenessOopClosure: public OopClosure {
G1CollectedHeap* g1h;
public:
VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
g1h = _g1h;
}
void do_oop(narrowOop *p) { do_oop_work(p); }
void do_oop( oop *p) { do_oop_work(p); }
template <class T> void do_oop_work(T *p) {
oop obj = oopDesc::load_decode_heap_oop(p);
guarantee(obj == NULL || !g1h->is_obj_dead(obj),
"Dead object referenced by a not dead object");
}
};
class VerifyObjsInRegionClosure: public ObjectClosure {
private:
G1CollectedHeap* _g1h;
size_t _live_bytes;
HeapRegion *_hr;
bool _use_prev_marking;
public:
// use_prev_marking == true -> use "prev" marking information,
// use_prev_marking == false -> use "next" marking information
VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
: _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
_g1h = G1CollectedHeap::heap();
}
void do_object(oop o) {
VerifyLivenessOopClosure isLive(_g1h);
assert(o != NULL, "Huh?");
if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
o->oop_iterate(&isLive);
if (!_hr->obj_allocated_since_prev_marking(o))
_live_bytes += (o->size() * HeapWordSize);
}
}
size_t live_bytes() { return _live_bytes; }
};
class PrintObjsInRegionClosure : public ObjectClosure {
HeapRegion *_hr;
G1CollectedHeap *_g1;
public:
PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
_g1 = G1CollectedHeap::heap();
};
void do_object(oop o) {
if (o != NULL) {
HeapWord *start = (HeapWord *) o;
size_t word_sz = o->size();
gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
" isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
(void*) o, word_sz,
_g1->isMarkedPrev(o),
_g1->isMarkedNext(o),
_hr->obj_allocated_since_prev_marking(o));
HeapWord *end = start + word_sz;
HeapWord *cur;
int *val;
for (cur = start; cur < end; cur++) {
val = (int *) cur;
gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
}
}
}
};
class VerifyRegionClosure: public HeapRegionClosure {
private:
bool _allow_dirty;
bool _par;
bool _use_prev_marking;
public:
// use_prev_marking == true -> use "prev" marking information,
// use_prev_marking == false -> use "next" marking information
VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
: _allow_dirty(allow_dirty),
_par(par),
_use_prev_marking(use_prev_marking) {}
bool doHeapRegion(HeapRegion* r) {
guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
"Should be unclaimed at verify points.");
if (!r->continuesHumongous()) {
VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
r->verify(_allow_dirty, _use_prev_marking);
r->object_iterate(¬_dead_yet_cl);
guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
"More live objects than counted in last complete marking.");
}
return false;
}
};
class VerifyRootsClosure: public OopsInGenClosure {
private:
G1CollectedHeap* _g1h;
bool _failures;
bool _use_prev_marking;
public:
// use_prev_marking == true -> use "prev" marking information,
// use_prev_marking == false -> use "next" marking information
VerifyRootsClosure(bool use_prev_marking) :
_g1h(G1CollectedHeap::heap()),
_failures(false),
_use_prev_marking(use_prev_marking) { }
bool failures() { return _failures; }
template <class T> void do_oop_nv(T* p) {
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
"points to dead obj "PTR_FORMAT, p, (void*) obj);
obj->print_on(gclog_or_tty);
_failures = true;
}
}
}
void do_oop(oop* p) { do_oop_nv(p); }
void do_oop(narrowOop* p) { do_oop_nv(p); }
};
// This is the task used for parallel heap verification.
class G1ParVerifyTask: public AbstractGangTask {
private:
G1CollectedHeap* _g1h;
bool _allow_dirty;
bool _use_prev_marking;
public:
// use_prev_marking == true -> use "prev" marking information,
// use_prev_marking == false -> use "next" marking information
G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
bool use_prev_marking) :
AbstractGangTask("Parallel verify task"),
_g1h(g1h),
_allow_dirty(allow_dirty),
_use_prev_marking(use_prev_marking) { }
void work(int worker_i) {
HandleMark hm;
VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
_g1h->heap_region_par_iterate_chunked(&blk, worker_i,
HeapRegion::ParVerifyClaimValue);
}
};
void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
verify(allow_dirty, silent, /* use_prev_marking */ true);
}
void G1CollectedHeap::verify(bool allow_dirty,
bool silent,
bool use_prev_marking) {
if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
if (!silent) { gclog_or_tty->print("roots "); }
VerifyRootsClosure rootsCl(use_prev_marking);
process_strong_roots(false,
SharedHeap::SO_AllClasses,
&rootsCl,
&rootsCl);
rem_set()->invalidate(perm_gen()->used_region(), false);
if (!silent) { gclog_or_tty->print("heapRegions "); }
if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
"sanity check");
G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
int n_workers = workers()->total_workers();
set_par_threads(n_workers);
workers()->run_task(&task);
set_par_threads(0);
assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
"sanity check");
reset_heap_region_claim_values();
assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
"sanity check");
} else {
VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
_hrs->iterate(&blk);
}
if (!silent) gclog_or_tty->print("remset ");
rem_set()->verify();
guarantee(!rootsCl.failures(), "should not have had failures");
} else {
if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
}
}
class PrintRegionClosure: public HeapRegionClosure {
outputStream* _st;
public:
PrintRegionClosure(outputStream* st) : _st(st) {}
bool doHeapRegion(HeapRegion* r) {
r->print_on(_st);
return false;
}
};
void G1CollectedHeap::print() const { print_on(tty); }
void G1CollectedHeap::print_on(outputStream* st) const {
print_on(st, PrintHeapAtGCExtended);
}
void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
st->print(" %-20s", "garbage-first heap");
st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
capacity()/K, used_unlocked()/K);
st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
_g1_storage.low_boundary(),
_g1_storage.high(),
_g1_storage.high_boundary());
st->cr();
st->print(" region size " SIZE_FORMAT "K, ",
HeapRegion::GrainBytes/K);
size_t young_regions = _young_list->length();
st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
young_regions, young_regions * HeapRegion::GrainBytes / K);
size_t survivor_regions = g1_policy()->recorded_survivor_regions();
st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
st->cr();
perm()->as_gen()->print_on(st);
if (extended) {
print_on_extended(st);
}
}
void G1CollectedHeap::print_on_extended(outputStream* st) const {
PrintRegionClosure blk(st);
_hrs->iterate(&blk);
}
class PrintOnThreadsClosure : public ThreadClosure {
outputStream* _st;
public:
PrintOnThreadsClosure(outputStream* st) : _st(st) { }
virtual void do_thread(Thread *t) {
t->print_on(_st);
}
};
void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
if (ParallelGCThreads > 0) {
workers()->print_worker_threads();
}
st->print("\"G1 concurrent mark GC Thread\" ");
_cmThread->print();
st->cr();
st->print("\"G1 concurrent refinement GC Threads\" ");
PrintOnThreadsClosure p(st);
_cg1r->threads_do(&p);
st->cr();
st->print("\"G1 zero-fill GC Thread\" ");
_czft->print_on(st);
st->cr();
}
void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
if (ParallelGCThreads > 0) {
workers()->threads_do(tc);
}
tc->do_thread(_cmThread);
_cg1r->threads_do(tc);
tc->do_thread(_czft);
}
void G1CollectedHeap::print_tracing_info() const {
concurrent_g1_refine()->print_final_card_counts();
// We'll overload this to mean "trace GC pause statistics."
if (TraceGen0Time || TraceGen1Time) {
// The "G1CollectorPolicy" is keeping track of these stats, so delegate
// to that.
g1_policy()->print_tracing_info();
}
if (G1SummarizeRSetStats) {
g1_rem_set()->print_summary_info();
}
if (G1SummarizeConcurrentMark) {
concurrent_mark()->print_summary_info();
}
if (G1SummarizeZFStats) {
ConcurrentZFThread::print_summary_info();
}
g1_policy()->print_yg_surv_rate_info();
GCOverheadReporter::printGCOverhead();
SpecializationStats::print();
}
int G1CollectedHeap::addr_to_arena_id(void* addr) const {
HeapRegion* hr = heap_region_containing(addr);
if (hr == NULL) {
return 0;
} else {
return 1;
}
}
G1CollectedHeap* G1CollectedHeap::heap() {
assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
"not a garbage-first heap");
return _g1h;
}
void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
// Call allocation profiler
AllocationProfiler::iterate_since_last_gc();
// Fill TLAB's and such
ensure_parsability(true);
}
void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
// FIXME: what is this about?
// I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
// is set.
COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
"derived pointer present"));
}
void G1CollectedHeap::do_collection_pause() {
// Read the GC count while holding the Heap_lock
// we need to do this _before_ wait_for_cleanup_complete(), to
// ensure that we do not give up the heap lock and potentially
// pick up the wrong count
int gc_count_before = SharedHeap::heap()->total_collections();
// Don't want to do a GC pause while cleanup is being completed!
wait_for_cleanup_complete();
g1_policy()->record_stop_world_start();
{
MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
VM_G1IncCollectionPause op(gc_count_before);
VMThread::execute(&op);
}
}
void
G1CollectedHeap::doConcurrentMark() {
MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
if (!_cmThread->in_progress()) {
_cmThread->set_started();
CGC_lock->notify();
}
}
class VerifyMarkedObjsClosure: public ObjectClosure {
G1CollectedHeap* _g1h;
public:
VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
void do_object(oop obj) {
assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
"markandsweep mark should agree with concurrent deadness");
}
};
void
G1CollectedHeap::checkConcurrentMark() {
VerifyMarkedObjsClosure verifycl(this);
// MutexLockerEx x(getMarkBitMapLock(),
// Mutex::_no_safepoint_check_flag);
object_iterate(&verifycl, false);
}
void G1CollectedHeap::do_sync_mark() {
_cm->checkpointRootsInitial();
_cm->markFromRoots();
_cm->checkpointRootsFinal(false);
}
// <NEW PREDICTION>
double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
bool young) {
return _g1_policy->predict_region_elapsed_time_ms(hr, young);
}
void G1CollectedHeap::check_if_region_is_too_expensive(double
predicted_time_ms) {
_g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
}
size_t G1CollectedHeap::pending_card_num() {
size_t extra_cards = 0;
JavaThread *curr = Threads::first();
while (curr != NULL) {
DirtyCardQueue& dcq = curr->dirty_card_queue();
extra_cards += dcq.size();
curr = curr->next();
}
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
size_t buffer_size = dcqs.buffer_size();
size_t buffer_num = dcqs.completed_buffers_num();
return buffer_size * buffer_num + extra_cards;
}
size_t G1CollectedHeap::max_pending_card_num() {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
size_t buffer_size = dcqs.buffer_size();
size_t buffer_num = dcqs.completed_buffers_num();
int thread_num = Threads::number_of_threads();
return (buffer_num + thread_num) * buffer_size;
}
size_t G1CollectedHeap::cards_scanned() {
HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
return g1_rset->cardsScanned();
}
void
G1CollectedHeap::setup_surviving_young_words() {
guarantee( _surviving_young_words == NULL, "pre-condition" );
size_t array_length = g1_policy()->young_cset_length();
_surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
if (_surviving_young_words == NULL) {
vm_exit_out_of_memory(sizeof(size_t) * array_length,
"Not enough space for young surv words summary.");
}
memset(_surviving_young_words, 0, array_length * sizeof(size_t));
#ifdef ASSERT
for (size_t i = 0; i < array_length; ++i) {
assert( _surviving_young_words[i] == 0, "memset above" );
}
#endif // !ASSERT
}
void
G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
size_t array_length = g1_policy()->young_cset_length();
for (size_t i = 0; i < array_length; ++i)
_surviving_young_words[i] += surv_young_words[i];
}
void
G1CollectedHeap::cleanup_surviving_young_words() {
guarantee( _surviving_young_words != NULL, "pre-condition" );
FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
_surviving_young_words = NULL;
}
// </NEW PREDICTION>
void
G1CollectedHeap::do_collection_pause_at_safepoint() {
if (PrintHeapAtGC) {
Universe::print_heap_before_gc();
}
{
char verbose_str[128];
sprintf(verbose_str, "GC pause ");
if (g1_policy()->in_young_gc_mode()) {
if (g1_policy()->full_young_gcs())
strcat(verbose_str, "(young)");
else
strcat(verbose_str, "(partial)");
}
if (g1_policy()->should_initiate_conc_mark())
strcat(verbose_str, " (initial-mark)");
GCCauseSetter x(this, GCCause::_g1_inc_collection_pause);
// if PrintGCDetails is on, we'll print long statistics information
// in the collector policy code, so let's not print this as the output
// is messy if we do.
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
ResourceMark rm;
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
guarantee(!is_gc_active(), "collection is not reentrant");
assert(regions_accounted_for(), "Region leakage!");
increment_gc_time_stamp();
if (g1_policy()->in_young_gc_mode()) {
assert(check_young_list_well_formed(),
"young list should be well formed");
}
if (GC_locker::is_active()) {
return; // GC is disabled (e.g. JNI GetXXXCritical operation)
}
bool abandoned = false;
{ // Call to jvmpi::post_class_unload_events must occur outside of active GC
IsGCActiveMark x;
gc_prologue(false);
increment_total_collections(false /* full gc */);
#if G1_REM_SET_LOGGING
gclog_or_tty->print_cr("\nJust chose CS, heap:");
print();
#endif
if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
prepare_for_verify();
gclog_or_tty->print(" VerifyBeforeGC:");
Universe::verify(false);
}
COMPILER2_PRESENT(DerivedPointerTable::clear());
// We want to turn off ref discovery, if necessary, and turn it back on
// on again later if we do. XXX Dubious: why is discovery disabled?
bool was_enabled = ref_processor()->discovery_enabled();
if (was_enabled) ref_processor()->disable_discovery();
// Forget the current alloc region (we might even choose it to be part
// of the collection set!).
abandon_cur_alloc_region();
// The elapsed time induced by the start time below deliberately elides
// the possible verification above.
double start_time_sec = os::elapsedTime();
GCOverheadReporter::recordSTWStart(start_time_sec);
size_t start_used_bytes = used();
g1_policy()->record_collection_pause_start(start_time_sec,
start_used_bytes);
guarantee(_in_cset_fast_test == NULL, "invariant");
guarantee(_in_cset_fast_test_base == NULL, "invariant");
_in_cset_fast_test_length = max_regions();
_in_cset_fast_test_base =
NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
memset(_in_cset_fast_test_base, false,
_in_cset_fast_test_length * sizeof(bool));
// We're biasing _in_cset_fast_test to avoid subtracting the
// beginning of the heap every time we want to index; basically
// it's the same with what we do with the card table.
_in_cset_fast_test = _in_cset_fast_test_base -
((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
#if SCAN_ONLY_VERBOSE
_young_list->print();
#endif // SCAN_ONLY_VERBOSE
if (g1_policy()->should_initiate_conc_mark()) {
concurrent_mark()->checkpointRootsInitialPre();
}
save_marks();
// We must do this before any possible evacuation that should propagate
// marks.
if (mark_in_progress()) {
double start_time_sec = os::elapsedTime();
_cm->drainAllSATBBuffers();
double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
g1_policy()->record_satb_drain_time(finish_mark_ms);
}
// Record the number of elements currently on the mark stack, so we
// only iterate over these. (Since evacuation may add to the mark
// stack, doing more exposes race conditions.) If no mark is in
// progress, this will be zero.
_cm->set_oops_do_bound();
assert(regions_accounted_for(), "Region leakage.");
if (mark_in_progress())
concurrent_mark()->newCSet();
// Now choose the CS.
g1_policy()->choose_collection_set();
// We may abandon a pause if we find no region that will fit in the MMU
// pause.
bool abandoned = (g1_policy()->collection_set() == NULL);
// Nothing to do if we were unable to choose a collection set.
if (!abandoned) {
#if G1_REM_SET_LOGGING
gclog_or_tty->print_cr("\nAfter pause, heap:");
print();
#endif
setup_surviving_young_words();
// Set up the gc allocation regions.
get_gc_alloc_regions();
// Actually do the work...
evacuate_collection_set();
free_collection_set(g1_policy()->collection_set());
g1_policy()->clear_collection_set();
FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
// this is more for peace of mind; we're nulling them here and
// we're expecting them to be null at the beginning of the next GC
_in_cset_fast_test = NULL;
_in_cset_fast_test_base = NULL;
release_gc_alloc_regions(false /* totally */);
cleanup_surviving_young_words();
if (g1_policy()->in_young_gc_mode()) {
_young_list->reset_sampled_info();
assert(check_young_list_empty(true),
"young list should be empty");
#if SCAN_ONLY_VERBOSE
_young_list->print();
#endif // SCAN_ONLY_VERBOSE
g1_policy()->record_survivor_regions(_young_list->survivor_length(),
_young_list->first_survivor_region(),
_young_list->last_survivor_region());
_young_list->reset_auxilary_lists();
}
} else {
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
}
if (evacuation_failed()) {
_summary_bytes_used = recalculate_used();
} else {
// The "used" of the the collection set have already been subtracted
// when they were freed. Add in the bytes evacuated.
_summary_bytes_used += g1_policy()->bytes_in_to_space();
}
if (g1_policy()->in_young_gc_mode() &&
g1_policy()->should_initiate_conc_mark()) {
concurrent_mark()->checkpointRootsInitialPost();
set_marking_started();
// CAUTION: after the doConcurrentMark() call below,
// the concurrent marking thread(s) could be running
// concurrently with us. Make sure that anything after
// this point does not assume that we are the only GC thread
// running. Note: of course, the actual marking work will
// not start until the safepoint itself is released in
// ConcurrentGCThread::safepoint_desynchronize().
doConcurrentMark();
}
#if SCAN_ONLY_VERBOSE
_young_list->print();
#endif // SCAN_ONLY_VERBOSE
double end_time_sec = os::elapsedTime();
double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
g1_policy()->record_pause_time_ms(pause_time_ms);
GCOverheadReporter::recordSTWEnd(end_time_sec);
g1_policy()->record_collection_pause_end(abandoned);
assert(regions_accounted_for(), "Region leakage.");
if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
gclog_or_tty->print(" VerifyAfterGC:");
prepare_for_verify();
Universe::verify(false);
}
if (was_enabled) ref_processor()->enable_discovery();
{
size_t expand_bytes = g1_policy()->expansion_amount();
if (expand_bytes > 0) {
size_t bytes_before = capacity();
expand(expand_bytes);
}
}
if (mark_in_progress()) {
concurrent_mark()->update_g1_committed();
}
#ifdef TRACESPINNING
ParallelTaskTerminator::print_termination_counts();
#endif
gc_epilogue(false);
}
assert(verify_region_lists(), "Bad region lists.");
if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
print_tracing_info();
vm_exit(-1);
}
}
if (PrintHeapAtGC) {
Universe::print_heap_after_gc();
}
}
void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
// make sure we don't call set_gc_alloc_region() multiple times on
// the same region
assert(r == NULL || !r->is_gc_alloc_region(),
"shouldn't already be a GC alloc region");
HeapWord* original_top = NULL;
if (r != NULL)
original_top = r->top();
// We will want to record the used space in r as being there before gc.
// One we install it as a GC alloc region it's eligible for allocation.
// So record it now and use it later.
size_t r_used = 0;
if (r != NULL) {
r_used = r->used();
if (ParallelGCThreads > 0) {
// need to take the lock to guard against two threads calling
// get_gc_alloc_region concurrently (very unlikely but...)
MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
r->save_marks();
}
}
HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
_gc_alloc_regions[purpose] = r;
if (old_alloc_region != NULL) {
// Replace aliases too.
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
if (_gc_alloc_regions[ap] == old_alloc_region) {
_gc_alloc_regions[ap] = r;
}
}
}
if (r != NULL) {
push_gc_alloc_region(r);
if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
// We are using a region as a GC alloc region after it has been used
// as a mutator allocation region during the current marking cycle.
// The mutator-allocated objects are currently implicitly marked, but
// when we move hr->next_top_at_mark_start() forward at the the end
// of the GC pause, they won't be. We therefore mark all objects in
// the "gap". We do this object-by-object, since marking densely
// does not currently work right with marking bitmap iteration. This
// means we rely on TLAB filling at the start of pauses, and no
// "resuscitation" of filled TLAB's. If we want to do this, we need
// to fix the marking bitmap iteration.
HeapWord* curhw = r->next_top_at_mark_start();
HeapWord* t = original_top;
while (curhw < t) {
oop cur = (oop)curhw;
// We'll assume parallel for generality. This is rare code.
concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
curhw = curhw + cur->size();
}
assert(curhw == t, "Should have parsed correctly.");
}
if (G1PolicyVerbose > 1) {
gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
"for survivors:", r->bottom(), original_top, r->end());
r->print();
}
g1_policy()->record_before_bytes(r_used);
}
}
void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
assert(Thread::current()->is_VM_thread() ||
par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
"Precondition.");
hr->set_is_gc_alloc_region(true);
hr->set_next_gc_alloc_region(_gc_alloc_region_list);
_gc_alloc_region_list = hr;
}
#ifdef G1_DEBUG
class FindGCAllocRegion: public HeapRegionClosure {
public:
bool doHeapRegion(HeapRegion* r) {
if (r->is_gc_alloc_region()) {
gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
r->hrs_index(), r->bottom());
}
return false;
}
};
#endif // G1_DEBUG
void G1CollectedHeap::forget_alloc_region_list() {
assert(Thread::current()->is_VM_thread(), "Precondition");
while (_gc_alloc_region_list != NULL) {
HeapRegion* r = _gc_alloc_region_list;
assert(r->is_gc_alloc_region(), "Invariant.");
// We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
// newly allocated data in order to be able to apply deferred updates
// before the GC is done for verification purposes (i.e to allow
// G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
// collection.
r->ContiguousSpace::set_saved_mark();
_gc_alloc_region_list = r->next_gc_alloc_region();
r->set_next_gc_alloc_region(NULL);
r->set_is_gc_alloc_region(false);
if (r->is_survivor()) {
if (r->is_empty()) {
r->set_not_young();
} else {
_young_list->add_survivor_region(r);
}
}
if (r->is_empty()) {
++_free_regions;
}
}
#ifdef G1_DEBUG
FindGCAllocRegion fa;
heap_region_iterate(&fa);
#endif // G1_DEBUG
}
bool G1CollectedHeap::check_gc_alloc_regions() {
// TODO: allocation regions check
return true;
}
void G1CollectedHeap::get_gc_alloc_regions() {
// First, let's check that the GC alloc region list is empty (it should)
assert(_gc_alloc_region_list == NULL, "invariant");
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
assert(_gc_alloc_regions[ap] == NULL, "invariant");
assert(_gc_alloc_region_counts[ap] == 0, "invariant");
// Create new GC alloc regions.
HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
_retained_gc_alloc_regions[ap] = NULL;
if (alloc_region != NULL) {
assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
// let's make sure that the GC alloc region is not tagged as such
// outside a GC operation
assert(!alloc_region->is_gc_alloc_region(), "sanity");
if (alloc_region->in_collection_set() ||
alloc_region->top() == alloc_region->end() ||
alloc_region->top() == alloc_region->bottom()) {
// we will discard the current GC alloc region if it's in the
// collection set (it can happen!), if it's already full (no
// point in using it), or if it's empty (this means that it
// was emptied during a cleanup and it should be on the free
// list now).
alloc_region = NULL;
}
}
if (alloc_region == NULL) {
// we will get a new GC alloc region
alloc_region = newAllocRegionWithExpansion(ap, 0);
} else {
// the region was retained from the last collection
++_gc_alloc_region_counts[ap];
}
if (alloc_region != NULL) {
assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
set_gc_alloc_region(ap, alloc_region);
}
assert(_gc_alloc_regions[ap] == NULL ||
_gc_alloc_regions[ap]->is_gc_alloc_region(),
"the GC alloc region should be tagged as such");
assert(_gc_alloc_regions[ap] == NULL ||
_gc_alloc_regions[ap] == _gc_alloc_region_list,
"the GC alloc region should be the same as the GC alloc list head");
}
// Set alternative regions for allocation purposes that have reached
// their limit.
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
_gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
}
}
assert(check_gc_alloc_regions(), "alloc regions messed up");
}
void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
// We keep a separate list of all regions that have been alloc regions in
// the current collection pause. Forget that now. This method will
// untag the GC alloc regions and tear down the GC alloc region
// list. It's desirable that no regions are tagged as GC alloc
// outside GCs.
forget_alloc_region_list();
// The current alloc regions contain objs that have survived
// collection. Make them no longer GC alloc regions.
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
HeapRegion* r = _gc_alloc_regions[ap];
_retained_gc_alloc_regions[ap] = NULL;
_gc_alloc_region_counts[ap] = 0;
if (r != NULL) {
// we retain nothing on _gc_alloc_regions between GCs
set_gc_alloc_region(ap, NULL);
if (r->is_empty()) {
// we didn't actually allocate anything in it; let's just put
// it on the free list
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
r->set_zero_fill_complete();
put_free_region_on_list_locked(r);
} else if (_retain_gc_alloc_region[ap] && !totally) {
// retain it so that we can use it at the beginning of the next GC
_retained_gc_alloc_regions[ap] = r;
}
}
}
}
#ifndef PRODUCT
// Useful for debugging
void G1CollectedHeap::print_gc_alloc_regions() {
gclog_or_tty->print_cr("GC alloc regions");
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
HeapRegion* r = _gc_alloc_regions[ap];
if (r == NULL) {
gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
} else {
gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
ap, r->bottom(), r->used());
}
}
}
#endif // PRODUCT
void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
_drain_in_progress = false;
set_evac_failure_closure(cl);
_evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
}
void G1CollectedHeap::finalize_for_evac_failure() {
assert(_evac_failure_scan_stack != NULL &&
_evac_failure_scan_stack->length() == 0,
"Postcondition");
assert(!_drain_in_progress, "Postcondition");
// Don't have to delete, since the scan stack is a resource object.
_evac_failure_scan_stack = NULL;
}
// *** Sequential G1 Evacuation
HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
HeapRegion* alloc_region = _gc_alloc_regions[purpose];
// let the caller handle alloc failure
if (alloc_region == NULL) return NULL;
assert(isHumongous(word_size) || !alloc_region->isHumongous(),
"Either the object is humongous or the region isn't");
HeapWord* block = alloc_region->allocate(word_size);
if (block == NULL) {
block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
}
return block;
}
class G1IsAliveClosure: public BoolObjectClosure {
G1CollectedHeap* _g1;
public:
G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
void do_object(oop p) { assert(false, "Do not call."); }
bool do_object_b(oop p) {
// It is reachable if it is outside the collection set, or is inside
// and forwarded.
#ifdef G1_DEBUG
gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
(void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
!_g1->obj_in_cs(p) || p->is_forwarded());
#endif // G1_DEBUG
return !_g1->obj_in_cs(p) || p->is_forwarded();
}
};
class G1KeepAliveClosure: public OopClosure {
G1CollectedHeap* _g1;
public:
G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
void do_oop( oop* p) {
oop obj = *p;
#ifdef G1_DEBUG
if (PrintGC && Verbose) {
gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
p, (void*) obj, (void*) *p);
}
#endif // G1_DEBUG
if (_g1->obj_in_cs(obj)) {
assert( obj->is_forwarded(), "invariant" );
*p = obj->forwardee();
#ifdef G1_DEBUG
gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
(void*) obj, (void*) *p);
#endif // G1_DEBUG
}
}
};
class UpdateRSetImmediate : public OopsInHeapRegionClosure {
private:
G1CollectedHeap* _g1;
G1RemSet* _g1_rem_set;
public:
UpdateRSetImmediate(G1CollectedHeap* g1) :
_g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
virtual void do_oop( oop* p) { do_oop_work(p); }
template <class T> void do_oop_work(T* p) {
assert(_from->is_in_reserved(p), "paranoia");
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
_g1_rem_set->par_write_ref(_from, p, 0);
}
}
};
class UpdateRSetDeferred : public OopsInHeapRegionClosure {
private:
G1CollectedHeap* _g1;
DirtyCardQueue *_dcq;
CardTableModRefBS* _ct_bs;
public:
UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
_g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
virtual void do_oop( oop* p) { do_oop_work(p); }
template <class T> void do_oop_work(T* p) {
assert(_from->is_in_reserved(p), "paranoia");
if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
!_from->is_survivor()) {
size_t card_index = _ct_bs->index_for(p);
if (_ct_bs->mark_card_deferred(card_index)) {
_dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
}
}
}
};
class RemoveSelfPointerClosure: public ObjectClosure {
private:
G1CollectedHeap* _g1;
ConcurrentMark* _cm;
HeapRegion* _hr;
size_t _prev_marked_bytes;
size_t _next_marked_bytes;
OopsInHeapRegionClosure *_cl;
public:
RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
_g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
_next_marked_bytes(0), _cl(cl) {}
size_t prev_marked_bytes() { return _prev_marked_bytes; }
size_t next_marked_bytes() { return _next_marked_bytes; }
// The original idea here was to coalesce evacuated and dead objects.
// However that caused complications with the block offset table (BOT).
// In particular if there were two TLABs, one of them partially refined.
// |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
// The BOT entries of the unrefined part of TLAB_2 point to the start
// of TLAB_2. If the last object of the TLAB_1 and the first object
// of TLAB_2 are coalesced, then the cards of the unrefined part
// would point into middle of the filler object.
//
// The current approach is to not coalesce and leave the BOT contents intact.
void do_object(oop obj) {
if (obj->is_forwarded() && obj->forwardee() == obj) {
// The object failed to move.
assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
_cm->markPrev(obj);
assert(_cm->isPrevMarked(obj), "Should be marked!");
_prev_marked_bytes += (obj->size() * HeapWordSize);
if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
_cm->markAndGrayObjectIfNecessary(obj);
}
obj->set_mark(markOopDesc::prototype());
// While we were processing RSet buffers during the
// collection, we actually didn't scan any cards on the
// collection set, since we didn't want to update remebered
// sets with entries that point into the collection set, given
// that live objects fromthe collection set are about to move
// and such entries will be stale very soon. This change also
// dealt with a reliability issue which involved scanning a
// card in the collection set and coming across an array that
// was being chunked and looking malformed. The problem is
// that, if evacuation fails, we might have remembered set
// entries missing given that we skipped cards on the
// collection set. So, we'll recreate such entries now.
obj->oop_iterate(_cl);
assert(_cm->isPrevMarked(obj), "Should be marked!");
} else {
// The object has been either evacuated or is dead. Fill it with a
// dummy object.
MemRegion mr((HeapWord*)obj, obj->size());
CollectedHeap::fill_with_object(mr);
_cm->clearRangeBothMaps(mr);
}
}
};
void G1CollectedHeap::remove_self_forwarding_pointers() {
UpdateRSetImmediate immediate_update(_g1h);
DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
UpdateRSetDeferred deferred_update(_g1h, &dcq);
OopsInHeapRegionClosure *cl;
if (G1DeferredRSUpdate) {
cl = &deferred_update;
} else {
cl = &immediate_update;
}
HeapRegion* cur = g1_policy()->collection_set();
while (cur != NULL) {
assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
RemoveSelfPointerClosure rspc(_g1h, cl);
if (cur->evacuation_failed()) {
assert(cur->in_collection_set(), "bad CS");
cl->set_region(cur);
cur->object_iterate(&rspc);
// A number of manipulations to make the TAMS be the current top,
// and the marked bytes be the ones observed in the iteration.
if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
// The comments below are the postconditions achieved by the
// calls. Note especially the last such condition, which says that
// the count of marked bytes has been properly restored.
cur->note_start_of_marking(false);
// _next_top_at_mark_start == top, _next_marked_bytes == 0
cur->add_to_marked_bytes(rspc.prev_marked_bytes());
// _next_marked_bytes == prev_marked_bytes.
cur->note_end_of_marking();
// _prev_top_at_mark_start == top(),
// _prev_marked_bytes == prev_marked_bytes
}
// If there is no mark in progress, we modified the _next variables
// above needlessly, but harmlessly.
if (_g1h->mark_in_progress()) {
cur->note_start_of_marking(false);
// _next_top_at_mark_start == top, _next_marked_bytes == 0
// _next_marked_bytes == next_marked_bytes.
}
// Now make sure the region has the right index in the sorted array.
g1_policy()->note_change_in_marked_bytes(cur);
}
cur = cur->next_in_collection_set();
}
assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
// Now restore saved marks, if any.
if (_objs_with_preserved_marks != NULL) {
assert(_preserved_marks_of_objs != NULL, "Both or none.");
assert(_objs_with_preserved_marks->length() ==
_preserved_marks_of_objs->length(), "Both or none.");
guarantee(_objs_with_preserved_marks->length() ==
_preserved_marks_of_objs->length(), "Both or none.");
for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
oop obj = _objs_with_preserved_marks->at(i);
markOop m = _preserved_marks_of_objs->at(i);
obj->set_mark(m);
}
// Delete the preserved marks growable arrays (allocated on the C heap).
delete _objs_with_preserved_marks;
delete _preserved_marks_of_objs;
_objs_with_preserved_marks = NULL;
_preserved_marks_of_objs = NULL;
}
}
void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
_evac_failure_scan_stack->push(obj);
}
void G1CollectedHeap::drain_evac_failure_scan_stack() {
assert(_evac_failure_scan_stack != NULL, "precondition");
while (_evac_failure_scan_stack->length() > 0) {
oop obj = _evac_failure_scan_stack->pop();
_evac_failure_closure->set_region(heap_region_containing(obj));
obj->oop_iterate_backwards(_evac_failure_closure);
}
}
void G1CollectedHeap::handle_evacuation_failure(oop old) {
markOop m = old->mark();
// forward to self
assert(!old->is_forwarded(), "precondition");
old->forward_to(old);
handle_evacuation_failure_common(old, m);
}
oop
G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
oop old) {
markOop m = old->mark();
oop forward_ptr = old->forward_to_atomic(old);
if (forward_ptr == NULL) {
// Forward-to-self succeeded.
if (_evac_failure_closure != cl) {
MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
assert(!_drain_in_progress,
"Should only be true while someone holds the lock.");
// Set the global evac-failure closure to the current thread's.
assert(_evac_failure_closure == NULL, "Or locking has failed.");
set_evac_failure_closure(cl);
// Now do the common part.
handle_evacuation_failure_common(old, m);
// Reset to NULL.
set_evac_failure_closure(NULL);
} else {
// The lock is already held, and this is recursive.
assert(_drain_in_progress, "This should only be the recursive case.");
handle_evacuation_failure_common(old, m);
}
return old;
} else {
// Someone else had a place to copy it.
return forward_ptr;
}
}
void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
set_evacuation_failed(true);
preserve_mark_if_necessary(old, m);
HeapRegion* r = heap_region_containing(old);
if (!r->evacuation_failed()) {
r->set_evacuation_failed(true);
if (G1PrintRegions) {
gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
"["PTR_FORMAT","PTR_FORMAT")\n",
r, r->bottom(), r->end());
}
}
push_on_evac_failure_scan_stack(old);
if (!_drain_in_progress) {
// prevent recursion in copy_to_survivor_space()
_drain_in_progress = true;
drain_evac_failure_scan_stack();
_drain_in_progress = false;
}
}
void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
if (m != markOopDesc::prototype()) {
if (_objs_with_preserved_marks == NULL) {
assert(_preserved_marks_of_objs == NULL, "Both or none.");
_objs_with_preserved_marks =
new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
_preserved_marks_of_objs =
new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
}
_objs_with_preserved_marks->push(obj);
_preserved_marks_of_objs->push(m);
}
}
// *** Parallel G1 Evacuation
HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
size_t word_size) {
HeapRegion* alloc_region = _gc_alloc_regions[purpose];
// let the caller handle alloc failure
if (alloc_region == NULL) return NULL;
HeapWord* block = alloc_region->par_allocate(word_size);
if (block == NULL) {
MutexLockerEx x(par_alloc_during_gc_lock(),
Mutex::_no_safepoint_check_flag);
block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
}
return block;
}
void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
bool par) {
// Another thread might have obtained alloc_region for the given
// purpose, and might be attempting to allocate in it, and might
// succeed. Therefore, we can't do the "finalization" stuff on the
// region below until we're sure the last allocation has happened.
// We ensure this by allocating the remaining space with a garbage
// object.
if (par) par_allocate_remaining_space(alloc_region);
// Now we can do the post-GC stuff on the region.
alloc_region->note_end_of_copying();
g1_policy()->record_after_bytes(alloc_region->used());
}
HeapWord*
G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
HeapRegion* alloc_region,
bool par,
size_t word_size) {
HeapWord* block = NULL;
// In the parallel case, a previous thread to obtain the lock may have
// already assigned a new gc_alloc_region.
if (alloc_region != _gc_alloc_regions[purpose]) {
assert(par, "But should only happen in parallel case.");
alloc_region = _gc_alloc_regions[purpose];
if (alloc_region == NULL) return NULL;
block = alloc_region->par_allocate(word_size);
if (block != NULL) return block;
// Otherwise, continue; this new region is empty, too.
}
assert(alloc_region != NULL, "We better have an allocation region");
retire_alloc_region(alloc_region, par);
if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
// Cannot allocate more regions for the given purpose.
GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
// Is there an alternative?
if (purpose != alt_purpose) {
HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
// Has not the alternative region been aliased?
if (alloc_region != alt_region && alt_region != NULL) {
// Try to allocate in the alternative region.
if (par) {
block = alt_region->par_allocate(word_size);
} else {
block = alt_region->allocate(word_size);
}
// Make an alias.
_gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
if (block != NULL) {
return block;
}
retire_alloc_region(alt_region, par);
}
// Both the allocation region and the alternative one are full
// and aliased, replace them with a new allocation region.
purpose = alt_purpose;
} else {
set_gc_alloc_region(purpose, NULL);
return NULL;
}
}
// Now allocate a new region for allocation.
alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
// let the caller handle alloc failure
if (alloc_region != NULL) {
assert(check_gc_alloc_regions(), "alloc regions messed up");
assert(alloc_region->saved_mark_at_top(),
"Mark should have been saved already.");
// We used to assert that the region was zero-filled here, but no
// longer.
// This must be done last: once it's installed, other regions may
// allocate in it (without holding the lock.)
set_gc_alloc_region(purpose, alloc_region);
if (par) {
block = alloc_region->par_allocate(word_size);
} else {
block = alloc_region->allocate(word_size);
}
// Caller handles alloc failure.
} else {
// This sets other apis using the same old alloc region to NULL, also.
set_gc_alloc_region(purpose, NULL);
}
return block; // May be NULL.
}
void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
HeapWord* block = NULL;
size_t free_words;
do {
free_words = r->free()/HeapWordSize;
// If there's too little space, no one can allocate, so we're done.
if (free_words < (size_t)oopDesc::header_size()) return;
// Otherwise, try to claim it.
block = r->par_allocate(free_words);
} while (block == NULL);
fill_with_object(block, free_words);
}
#ifndef PRODUCT
bool GCLabBitMapClosure::do_bit(size_t offset) {
HeapWord* addr = _bitmap->offsetToHeapWord(offset);
guarantee(_cm->isMarked(oop(addr)), "it should be!");
return true;
}
#endif // PRODUCT
G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
: _g1h(g1h),
_refs(g1h->task_queue(queue_num)),
_dcq(&g1h->dirty_card_queue_set()),
_ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
_g1_rem(g1h->g1_rem_set()),
_hash_seed(17), _queue_num(queue_num),
_term_attempts(0),
_age_table(false),
#if G1_DETAILED_STATS
_pushes(0), _pops(0), _steals(0),
_steal_attempts(0), _overflow_pushes(0),
#endif
_strong_roots_time(0), _term_time(0),
_alloc_buffer_waste(0), _undo_waste(0)
{
// we allocate G1YoungSurvRateNumRegions plus one entries, since
// we "sacrifice" entry 0 to keep track of surviving bytes for
// non-young regions (where the age is -1)
// We also add a few elements at the beginning and at the end in
// an attempt to eliminate cache contention
size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
size_t array_length = PADDING_ELEM_NUM +
real_length +
PADDING_ELEM_NUM;
_surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
if (_surviving_young_words_base == NULL)
vm_exit_out_of_memory(array_length * sizeof(size_t),
"Not enough space for young surv histo.");
_surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
memset(_surviving_young_words, 0, real_length * sizeof(size_t));
_overflowed_refs = new OverflowQueue(10);
_start = os::elapsedTime();
}
G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
_g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
_par_scan_state(par_scan_state) { }
template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
// This is called _after_ do_oop_work has been called, hence after
// the object has been relocated to its new location and *p points
// to its new location.
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
oop obj = oopDesc::decode_heap_oop(heap_oop);
assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
"shouldn't still be in the CSet if evacuation didn't fail.");
HeapWord* addr = (HeapWord*)obj;
if (_g1->is_in_g1_reserved(addr))
_cm->grayRoot(oop(addr));
}
}
oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
size_t word_sz = old->size();
HeapRegion* from_region = _g1->heap_region_containing_raw(old);
// +1 to make the -1 indexes valid...
int young_index = from_region->young_index_in_cset()+1;
assert( (from_region->is_young() && young_index > 0) ||
(!from_region->is_young() && young_index == 0), "invariant" );
G1CollectorPolicy* g1p = _g1->g1_policy();
markOop m = old->mark();
int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
: m->age();
GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
word_sz);
HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
oop obj = oop(obj_ptr);
if (obj_ptr == NULL) {
// This will either forward-to-self, or detect that someone else has
// installed a forwarding pointer.
OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
return _g1->handle_evacuation_failure_par(cl, old);
}
// We're going to allocate linearly, so might as well prefetch ahead.
Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
oop forward_ptr = old->forward_to_atomic(obj);
if (forward_ptr == NULL) {
Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
if (g1p->track_object_age(alloc_purpose)) {
// We could simply do obj->incr_age(). However, this causes a
// performance issue. obj->incr_age() will first check whether
// the object has a displaced mark by checking its mark word;
// getting the mark word from the new location of the object
// stalls. So, given that we already have the mark word and we
// are about to install it anyway, it's better to increase the
// age on the mark word, when the object does not have a
// displaced mark word. We're not expecting many objects to have
// a displaced marked word, so that case is not optimized
// further (it could be...) and we simply call obj->incr_age().
if (m->has_displaced_mark_helper()) {
// in this case, we have to install the mark word first,
// otherwise obj looks to be forwarded (the old mark word,
// which contains the forward pointer, was copied)
obj->set_mark(m);
obj->incr_age();
} else {
m = m->incr_age();
obj->set_mark(m);
}
_par_scan_state->age_table()->add(obj, word_sz);
} else {
obj->set_mark(m);
}
// preserve "next" mark bit
if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
if (!use_local_bitmaps ||
!_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
// if we couldn't mark it on the local bitmap (this happens when
// the object was not allocated in the GCLab), we have to bite
// the bullet and do the standard parallel mark
_cm->markAndGrayObjectIfNecessary(obj);
}
#if 1
if (_g1->isMarkedNext(old)) {
_cm->nextMarkBitMap()->parClear((HeapWord*)old);
}
#endif
}
size_t* surv_young_words = _par_scan_state->surviving_young_words();
surv_young_words[young_index] += word_sz;
if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
arrayOop(old)->set_length(0);
oop* old_p = set_partial_array_mask(old);
_par_scan_state->push_on_queue(old_p);
} else {
// No point in using the slower heap_region_containing() method,
// given that we know obj is in the heap.
_scanner->set_region(_g1->heap_region_containing_raw(obj));
obj->oop_iterate_backwards(_scanner);
}
} else {
_par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
obj = forward_ptr;
}
return obj;
}
template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee, bool skip_cset_test>
template <class T>
void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee, skip_cset_test>
::do_oop_work(T* p) {
oop obj = oopDesc::load_decode_heap_oop(p);
assert(barrier != G1BarrierRS || obj != NULL,
"Precondition: G1BarrierRS implies obj is nonNull");
// The only time we skip the cset test is when we're scanning
// references popped from the queue. And we only push on the queue
// references that we know point into the cset, so no point in
// checking again. But we'll leave an assert here for peace of mind.
assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
// here the null check is implicit in the cset_fast_test() test
if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
#if G1_REM_SET_LOGGING
gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
"into CS.", p, (void*) obj);
#endif
if (obj->is_forwarded()) {
oopDesc::encode_store_heap_oop(p, obj->forwardee());
} else {
oop copy_oop = copy_to_survivor_space(obj);
oopDesc::encode_store_heap_oop(p, copy_oop);
}
// When scanning the RS, we only care about objs in CS.
if (barrier == G1BarrierRS) {
_par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
}
}
// When scanning moved objs, must look at all oops.
if (barrier == G1BarrierEvac && obj != NULL) {
_par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
}
if (do_gen_barrier && obj != NULL) {
par_do_barrier(p);
}
}
template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(narrowOop* p);
template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
assert(has_partial_array_mask(p), "invariant");
oop old = clear_partial_array_mask(p);
assert(old->is_objArray(), "must be obj array");
assert(old->is_forwarded(), "must be forwarded");
assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
objArrayOop obj = objArrayOop(old->forwardee());
assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
// Process ParGCArrayScanChunk elements now
// and push the remainder back onto queue
int start = arrayOop(old)->length();
int end = obj->length();
int remainder = end - start;
assert(start <= end, "just checking");
if (remainder > 2 * ParGCArrayScanChunk) {
// Test above combines last partial chunk with a full chunk
end = start + ParGCArrayScanChunk;
arrayOop(old)->set_length(end);
// Push remainder.
oop* old_p = set_partial_array_mask(old);
assert(arrayOop(old)->length() < obj->length(), "Empty push?");
_par_scan_state->push_on_queue(old_p);
} else {
// Restore length so that the heap remains parsable in
// case of evacuation failure.
arrayOop(old)->set_length(end);
}
_scanner.set_region(_g1->heap_region_containing_raw(obj));
// process our set of indices (include header in first chunk)
obj->oop_iterate_range(&_scanner, start, end);
}
class G1ParEvacuateFollowersClosure : public VoidClosure {
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) {}
void do_void() {
G1ParScanThreadState* pss = par_scan_state();
while (true) {
pss->trim_queue();
IF_G1_DETAILED_STATS(pss->note_steal_attempt());
StarTask stolen_task;
if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
IF_G1_DETAILED_STATS(pss->note_steal());
// slightly paranoid tests; I'm trying to catch potential
// problems before we go into push_on_queue to know where the
// problem is coming from
assert((oop*)stolen_task != NULL, "Error");
if (stolen_task.is_narrow()) {
assert(UseCompressedOops, "Error");
narrowOop* p = (narrowOop*) stolen_task;
assert(has_partial_array_mask(p) ||
_g1h->obj_in_cs(oopDesc::load_decode_heap_oop(p)), "Error");
pss->push_on_queue(p);
} else {
oop* p = (oop*) stolen_task;
assert(has_partial_array_mask(p) || _g1h->obj_in_cs(*p), "Error");
pss->push_on_queue(p);
}
continue;
}
pss->start_term_time();
if (terminator()->offer_termination()) break;
pss->end_term_time();
}
pss->end_term_time();
pss->retire_alloc_buffers();
}
};
class G1ParTask : public AbstractGangTask {
protected:
G1CollectedHeap* _g1h;
RefToScanQueueSet *_queues;
ParallelTaskTerminator _terminator;
int _n_workers;
Mutex _stats_lock;
Mutex* stats_lock() { return &_stats_lock; }
size_t getNCards() {
return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
/ G1BlockOffsetSharedArray::N_bytes;
}
public:
G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
: AbstractGangTask("G1 collection"),
_g1h(g1h),
_queues(task_queues),
_terminator(workers, _queues),
_stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
_n_workers(workers)
{}
RefToScanQueueSet* queues() { return _queues; }
RefToScanQueue *work_queue(int i) {
return queues()->queue(i);
}
void work(int i) {
if (i >= _n_workers) return; // no work needed this round
ResourceMark rm;
HandleMark hm;
G1ParScanThreadState pss(_g1h, i);
G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
pss.set_evac_closure(&scan_evac_cl);
pss.set_evac_failure_closure(&evac_failure_cl);
pss.set_partial_scan_closure(&partial_scan_cl);
G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
OopsInHeapRegionClosure *scan_root_cl;
OopsInHeapRegionClosure *scan_perm_cl;
OopsInHeapRegionClosure *scan_so_cl;
if (_g1h->g1_policy()->should_initiate_conc_mark()) {
scan_root_cl = &scan_mark_root_cl;
scan_perm_cl = &scan_mark_perm_cl;
scan_so_cl = &scan_mark_heap_rs_cl;
} else {
scan_root_cl = &only_scan_root_cl;
scan_perm_cl = &only_scan_perm_cl;
scan_so_cl = &only_scan_heap_rs_cl;
}
pss.start_strong_roots();
_g1h->g1_process_strong_roots(/* not collecting perm */ false,
SharedHeap::SO_AllClasses,
scan_root_cl,
&only_scan_heap_rs_cl,
scan_so_cl,
scan_perm_cl,
i);
pss.end_strong_roots();
{
double start = os::elapsedTime();
G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
evac.do_void();
double elapsed_ms = (os::elapsedTime()-start)*1000.0;
double term_ms = pss.term_time()*1000.0;
_g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
_g1h->g1_policy()->record_termination_time(i, term_ms);
}
if (G1UseSurvivorSpaces) {
_g1h->g1_policy()->record_thread_age_table(pss.age_table());
}
_g1h->update_surviving_young_words(pss.surviving_young_words()+1);
// Clean up any par-expanded rem sets.
HeapRegionRemSet::par_cleanup();
MutexLocker x(stats_lock());
if (ParallelGCVerbose) {
gclog_or_tty->print("Thread %d complete:\n", i);
#if G1_DETAILED_STATS
gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
pss.pushes(),
pss.pops(),
pss.overflow_pushes(),
pss.steals(),
pss.steal_attempts());
#endif
double elapsed = pss.elapsed();
double strong_roots = pss.strong_roots_time();
double term = pss.term_time();
gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
" Strong roots: %7.2f ms (%6.2f%%)\n"
" Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
elapsed * 1000.0,
strong_roots * 1000.0, (strong_roots*100.0/elapsed),
term * 1000.0, (term*100.0/elapsed),
pss.term_attempts());
size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
gclog_or_tty->print(" Waste: %8dK\n"
" Alloc Buffer: %8dK\n"
" Undo: %8dK\n",
(total_waste * HeapWordSize) / K,
(pss.alloc_buffer_waste() * HeapWordSize) / K,
(pss.undo_waste() * HeapWordSize) / K);
}
assert(pss.refs_to_scan() == 0, "Task queue should be empty");
assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
}
};
// *** Common G1 Evacuation Stuff
void
G1CollectedHeap::
g1_process_strong_roots(bool collecting_perm_gen,
SharedHeap::ScanningOption so,
OopClosure* scan_non_heap_roots,
OopsInHeapRegionClosure* scan_rs,
OopsInHeapRegionClosure* scan_so,
OopsInGenClosure* scan_perm,
int worker_i) {
// First scan the strong roots, including the perm gen.
double ext_roots_start = os::elapsedTime();
double closure_app_time_sec = 0.0;
BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
BufferingOopsInGenClosure buf_scan_perm(scan_perm);
buf_scan_perm.set_generation(perm_gen());
process_strong_roots(collecting_perm_gen, so,
&buf_scan_non_heap_roots,
&buf_scan_perm);
// Finish up any enqueued closure apps.
buf_scan_non_heap_roots.done();
buf_scan_perm.done();
double ext_roots_end = os::elapsedTime();
g1_policy()->reset_obj_copy_time(worker_i);
double obj_copy_time_sec =
buf_scan_non_heap_roots.closure_app_seconds() +
buf_scan_perm.closure_app_seconds();
g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
double ext_root_time_ms =
((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
// Scan strong roots in mark stack.
if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
concurrent_mark()->oops_do(scan_non_heap_roots);
}
double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
// XXX What should this be doing in the parallel case?
g1_policy()->record_collection_pause_end_CH_strong_roots();
if (scan_so != NULL) {
scan_scan_only_set(scan_so, worker_i);
}
// Now scan the complement of the collection set.
if (scan_rs != NULL) {
g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
}
// Finish with the ref_processor roots.
if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
ref_processor()->oops_do(scan_non_heap_roots);
}
g1_policy()->record_collection_pause_end_G1_strong_roots();
_process_strong_tasks->all_tasks_completed();
}
void
G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
OopsInHeapRegionClosure* oc,
int worker_i) {
HeapWord* startAddr = r->bottom();
HeapWord* endAddr = r->used_region().end();
oc->set_region(r);
HeapWord* p = r->bottom();
HeapWord* t = r->top();
guarantee( p == r->next_top_at_mark_start(), "invariant" );
while (p < t) {
oop obj = oop(p);
p += obj->oop_iterate(oc);
}
}
void
G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
int worker_i) {
double start = os::elapsedTime();
BufferingOopsInHeapRegionClosure boc(oc);
FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
OopsInHeapRegionClosure *foc;
if (g1_policy()->should_initiate_conc_mark())
foc = &scan_and_mark;
else
foc = &scan_only;
HeapRegion* hr;
int n = 0;
while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
scan_scan_only_region(hr, foc, worker_i);
++n;
}
boc.done();
double closure_app_s = boc.closure_app_seconds();
g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
g1_policy()->record_scan_only_time(worker_i, ms, n);
}
void
G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
OopClosure* non_root_closure) {
SharedHeap::process_weak_roots(root_closure, non_root_closure);
}
class SaveMarksClosure: public HeapRegionClosure {
public:
bool doHeapRegion(HeapRegion* r) {
r->save_marks();
return false;
}
};
void G1CollectedHeap::save_marks() {
if (ParallelGCThreads == 0) {
SaveMarksClosure sm;
heap_region_iterate(&sm);
}
// We do this even in the parallel case
perm_gen()->save_marks();
}
void G1CollectedHeap::evacuate_collection_set() {
set_evacuation_failed(false);
g1_rem_set()->prepare_for_oops_into_collection_set_do();
concurrent_g1_refine()->set_use_cache(false);
int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
set_par_threads(n_workers);
G1ParTask g1_par_task(this, n_workers, _task_queues);
init_for_evac_failure(NULL);
change_strong_roots_parity(); // In preparation for parallel strong roots.
rem_set()->prepare_for_younger_refs_iterate(true);
assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
double start_par = os::elapsedTime();
if (ParallelGCThreads > 0) {
// The individual threads will set their evac-failure closures.
workers()->run_task(&g1_par_task);
} else {
g1_par_task.work(0);
}
double par_time = (os::elapsedTime() - start_par) * 1000.0;
g1_policy()->record_par_time(par_time);
set_par_threads(0);
// Is this the right thing to do here? We don't save marks
// on individual heap regions when we allocate from
// them in parallel, so this seems like the correct place for this.
retire_all_alloc_regions();
{
G1IsAliveClosure is_alive(this);
G1KeepAliveClosure keep_alive(this);
JNIHandles::weak_oops_do(&is_alive, &keep_alive);
}
g1_rem_set()->cleanup_after_oops_into_collection_set_do();
concurrent_g1_refine()->set_use_cache(true);
finalize_for_evac_failure();
// Must do this before removing self-forwarding pointers, which clears
// the per-region evac-failure flags.
concurrent_mark()->complete_marking_in_collection_set();
if (evacuation_failed()) {
remove_self_forwarding_pointers();
if (PrintGCDetails) {
gclog_or_tty->print(" (evacuation failed)");
} else if (PrintGC) {
gclog_or_tty->print("--");
}
}
if (G1DeferredRSUpdate) {
RedirtyLoggedCardTableEntryFastClosure redirty;
dirty_card_queue_set().set_closure(&redirty);
dirty_card_queue_set().apply_closure_to_all_completed_buffers();
JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
}
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
}
void G1CollectedHeap::free_region(HeapRegion* hr) {
size_t pre_used = 0;
size_t cleared_h_regions = 0;
size_t freed_regions = 0;
UncleanRegionList local_list;
HeapWord* start = hr->bottom();
HeapWord* end = hr->prev_top_at_mark_start();
size_t used_bytes = hr->used();
size_t live_bytes = hr->max_live_bytes();
if (used_bytes > 0) {
guarantee( live_bytes <= used_bytes, "invariant" );
} else {
guarantee( live_bytes == 0, "invariant" );
}
size_t garbage_bytes = used_bytes - live_bytes;
if (garbage_bytes > 0)
g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
&local_list);
finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
&local_list);
}
void
G1CollectedHeap::free_region_work(HeapRegion* hr,
size_t& pre_used,
size_t& cleared_h_regions,
size_t& freed_regions,
UncleanRegionList* list,
bool par) {
pre_used += hr->used();
if (hr->isHumongous()) {
assert(hr->startsHumongous(),
"Only the start of a humongous region should be freed.");
int ind = _hrs->find(hr);
assert(ind != -1, "Should have an index.");
// Clear the start region.
hr->hr_clear(par, true /*clear_space*/);
list->insert_before_head(hr);
cleared_h_regions++;
freed_regions++;
// Clear any continued regions.
ind++;
while ((size_t)ind < n_regions()) {
HeapRegion* hrc = _hrs->at(ind);
if (!hrc->continuesHumongous()) break;
// Otherwise, does continue the H region.
assert(hrc->humongous_start_region() == hr, "Huh?");
hrc->hr_clear(par, true /*clear_space*/);
cleared_h_regions++;
freed_regions++;
list->insert_before_head(hrc);
ind++;
}
} else {
hr->hr_clear(par, true /*clear_space*/);
list->insert_before_head(hr);
freed_regions++;
// If we're using clear2, this should not be enabled.
// assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
}
}
void G1CollectedHeap::finish_free_region_work(size_t pre_used,
size_t cleared_h_regions,
size_t freed_regions,
UncleanRegionList* list) {
if (list != NULL && list->sz() > 0) {
prepend_region_list_on_unclean_list(list);
}
// Acquire a lock, if we're parallel, to update possibly-shared
// variables.
Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
{
MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
_summary_bytes_used -= pre_used;
_num_humongous_regions -= (int) cleared_h_regions;
_free_regions += freed_regions;
}
}
void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
while (list != NULL) {
guarantee( list->is_young(), "invariant" );
HeapWord* bottom = list->bottom();
HeapWord* end = list->end();
MemRegion mr(bottom, end);
ct_bs->dirty(mr);
list = list->get_next_young_region();
}
}
class G1ParCleanupCTTask : public AbstractGangTask {
CardTableModRefBS* _ct_bs;
G1CollectedHeap* _g1h;
public:
G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
G1CollectedHeap* g1h) :
AbstractGangTask("G1 Par Cleanup CT Task"),
_ct_bs(ct_bs),
_g1h(g1h)
{ }
void work(int i) {
HeapRegion* r;
while (r = _g1h->pop_dirty_cards_region()) {
clear_cards(r);
}
}
void clear_cards(HeapRegion* r) {
// Cards for Survivor and Scan-Only regions will be dirtied later.
if (!r->is_scan_only() && !r->is_survivor()) {
_ct_bs->clear(MemRegion(r->bottom(), r->end()));
}
}
};
void G1CollectedHeap::cleanUpCardTable() {
CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
double start = os::elapsedTime();
// Iterate over the dirty cards region list.
G1ParCleanupCTTask cleanup_task(ct_bs, this);
if (ParallelGCThreads > 0) {
set_par_threads(workers()->total_workers());
workers()->run_task(&cleanup_task);
set_par_threads(0);
} else {
while (_dirty_cards_region_list) {
HeapRegion* r = _dirty_cards_region_list;
cleanup_task.clear_cards(r);
_dirty_cards_region_list = r->get_next_dirty_cards_region();
if (_dirty_cards_region_list == r) {
// The last region.
_dirty_cards_region_list = NULL;
}
r->set_next_dirty_cards_region(NULL);
}
}
// now, redirty the cards of the scan-only and survivor regions
// (it seemed faster to do it this way, instead of iterating over
// all regions and then clearing / dirtying as appropriate)
dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
double elapsed = os::elapsedTime() - start;
g1_policy()->record_clear_ct_time( elapsed * 1000.0);
}
void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
if (g1_policy()->should_do_collection_pause(word_size)) {
do_collection_pause();
}
}
void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
double young_time_ms = 0.0;
double non_young_time_ms = 0.0;
G1CollectorPolicy* policy = g1_policy();
double start_sec = os::elapsedTime();
bool non_young = true;
HeapRegion* cur = cs_head;
int age_bound = -1;
size_t rs_lengths = 0;
while (cur != NULL) {
if (non_young) {
if (cur->is_young()) {
double end_sec = os::elapsedTime();
double elapsed_ms = (end_sec - start_sec) * 1000.0;
non_young_time_ms += elapsed_ms;
start_sec = os::elapsedTime();
non_young = false;
}
} else {
if (!cur->is_on_free_list()) {
double end_sec = os::elapsedTime();
double elapsed_ms = (end_sec - start_sec) * 1000.0;
young_time_ms += elapsed_ms;
start_sec = os::elapsedTime();
non_young = true;
}
}
rs_lengths += cur->rem_set()->occupied();
HeapRegion* next = cur->next_in_collection_set();
assert(cur->in_collection_set(), "bad CS");
cur->set_next_in_collection_set(NULL);
cur->set_in_collection_set(false);
if (cur->is_young()) {
int index = cur->young_index_in_cset();
guarantee( index != -1, "invariant" );
guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
size_t words_survived = _surviving_young_words[index];
cur->record_surv_words_in_group(words_survived);
} else {
int index = cur->young_index_in_cset();
guarantee( index == -1, "invariant" );
}
assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
(!cur->is_young() && cur->young_index_in_cset() == -1),
"invariant" );
if (!cur->evacuation_failed()) {
// And the region is empty.
assert(!cur->is_empty(),
"Should not have empty regions in a CS.");
free_region(cur);
} else {
guarantee( !cur->is_scan_only(), "should not be scan only" );
cur->uninstall_surv_rate_group();
if (cur->is_young())
cur->set_young_index_in_cset(-1);
cur->set_not_young();
cur->set_evacuation_failed(false);
}
cur = next;
}
policy->record_max_rs_lengths(rs_lengths);
policy->cset_regions_freed();
double end_sec = os::elapsedTime();
double elapsed_ms = (end_sec - start_sec) * 1000.0;
if (non_young)
non_young_time_ms += elapsed_ms;
else
young_time_ms += elapsed_ms;
policy->record_young_free_cset_time_ms(young_time_ms);
policy->record_non_young_free_cset_time_ms(non_young_time_ms);
}
HeapRegion*
G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
assert(ZF_mon->owned_by_self(), "Precondition");
HeapRegion* res = pop_unclean_region_list_locked();
if (res != NULL) {
assert(!res->continuesHumongous() &&
res->zero_fill_state() != HeapRegion::Allocated,
"Only free regions on unclean list.");
if (zero_filled) {
res->ensure_zero_filled_locked();
res->set_zero_fill_allocated();
}
}
return res;
}
HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
return alloc_region_from_unclean_list_locked(zero_filled);
}
void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
put_region_on_unclean_list_locked(r);
if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
}
void G1CollectedHeap::set_unclean_regions_coming(bool b) {
MutexLockerEx x(Cleanup_mon);
set_unclean_regions_coming_locked(b);
}
void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
assert(Cleanup_mon->owned_by_self(), "Precondition");
_unclean_regions_coming = b;
// Wake up mutator threads that might be waiting for completeCleanup to
// finish.
if (!b) Cleanup_mon->notify_all();
}
void G1CollectedHeap::wait_for_cleanup_complete() {
MutexLockerEx x(Cleanup_mon);
wait_for_cleanup_complete_locked();
}
void G1CollectedHeap::wait_for_cleanup_complete_locked() {
assert(Cleanup_mon->owned_by_self(), "precondition");
while (_unclean_regions_coming) {
Cleanup_mon->wait();
}
}
void
G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
assert(ZF_mon->owned_by_self(), "precondition.");
_unclean_region_list.insert_before_head(r);
}
void
G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
prepend_region_list_on_unclean_list_locked(list);
if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
}
void
G1CollectedHeap::
prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
assert(ZF_mon->owned_by_self(), "precondition.");
_unclean_region_list.prepend_list(list);
}
HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
assert(ZF_mon->owned_by_self(), "precondition.");
HeapRegion* res = _unclean_region_list.pop();
if (res != NULL) {
// Inform ZF thread that there's a new unclean head.
if (_unclean_region_list.hd() != NULL && should_zf())
ZF_mon->notify_all();
}
return res;
}
HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
assert(ZF_mon->owned_by_self(), "precondition.");
return _unclean_region_list.hd();
}
bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
assert(ZF_mon->owned_by_self(), "Precondition");
HeapRegion* r = peek_unclean_region_list_locked();
if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
// Result of below must be equal to "r", since we hold the lock.
(void)pop_unclean_region_list_locked();
put_free_region_on_list_locked(r);
return true;
} else {
return false;
}
}
bool G1CollectedHeap::move_cleaned_region_to_free_list() {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
return move_cleaned_region_to_free_list_locked();
}
void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
assert(ZF_mon->owned_by_self(), "precondition.");
assert(_free_region_list_size == free_region_list_length(), "Inv");
assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
"Regions on free list must be zero filled");
assert(!r->isHumongous(), "Must not be humongous.");
assert(r->is_empty(), "Better be empty");
assert(!r->is_on_free_list(),
"Better not already be on free list");
assert(!r->is_on_unclean_list(),
"Better not already be on unclean list");
r->set_on_free_list(true);
r->set_next_on_free_list(_free_region_list);
_free_region_list = r;
_free_region_list_size++;
assert(_free_region_list_size == free_region_list_length(), "Inv");
}
void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
put_free_region_on_list_locked(r);
}
HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
assert(ZF_mon->owned_by_self(), "precondition.");
assert(_free_region_list_size == free_region_list_length(), "Inv");
HeapRegion* res = _free_region_list;
if (res != NULL) {
_free_region_list = res->next_from_free_list();
_free_region_list_size--;
res->set_on_free_list(false);
res->set_next_on_free_list(NULL);
assert(_free_region_list_size == free_region_list_length(), "Inv");
}
return res;
}
HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
// By self, or on behalf of self.
assert(Heap_lock->is_locked(), "Precondition");
HeapRegion* res = NULL;
bool first = true;
while (res == NULL) {
if (zero_filled || !first) {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
res = pop_free_region_list_locked();
if (res != NULL) {
assert(!res->zero_fill_is_allocated(),
"No allocated regions on free list.");
res->set_zero_fill_allocated();
} else if (!first) {
break; // We tried both, time to return NULL.
}
}
if (res == NULL) {
res = alloc_region_from_unclean_list(zero_filled);
}
assert(res == NULL ||
!zero_filled ||
res->zero_fill_is_allocated(),
"We must have allocated the region we're returning");
first = false;
}
return res;
}
void G1CollectedHeap::remove_allocated_regions_from_lists() {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
{
HeapRegion* prev = NULL;
HeapRegion* cur = _unclean_region_list.hd();
while (cur != NULL) {
HeapRegion* next = cur->next_from_unclean_list();
if (cur->zero_fill_is_allocated()) {
// Remove from the list.
if (prev == NULL) {
(void)_unclean_region_list.pop();
} else {
_unclean_region_list.delete_after(prev);
}
cur->set_on_unclean_list(false);
cur->set_next_on_unclean_list(NULL);
} else {
prev = cur;
}
cur = next;
}
assert(_unclean_region_list.sz() == unclean_region_list_length(),
"Inv");
}
{
HeapRegion* prev = NULL;
HeapRegion* cur = _free_region_list;
while (cur != NULL) {
HeapRegion* next = cur->next_from_free_list();
if (cur->zero_fill_is_allocated()) {
// Remove from the list.
if (prev == NULL) {
_free_region_list = cur->next_from_free_list();
} else {
prev->set_next_on_free_list(cur->next_from_free_list());
}
cur->set_on_free_list(false);
cur->set_next_on_free_list(NULL);
_free_region_list_size--;
} else {
prev = cur;
}
cur = next;
}
assert(_free_region_list_size == free_region_list_length(), "Inv");
}
}
bool G1CollectedHeap::verify_region_lists() {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
return verify_region_lists_locked();
}
bool G1CollectedHeap::verify_region_lists_locked() {
HeapRegion* unclean = _unclean_region_list.hd();
while (unclean != NULL) {
guarantee(unclean->is_on_unclean_list(), "Well, it is!");
guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
"Everything else is possible.");
unclean = unclean->next_from_unclean_list();
}
guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
HeapRegion* free_r = _free_region_list;
while (free_r != NULL) {
assert(free_r->is_on_free_list(), "Well, it is!");
assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
switch (free_r->zero_fill_state()) {
case HeapRegion::NotZeroFilled:
case HeapRegion::ZeroFilling:
guarantee(false, "Should not be on free list.");
break;
default:
// Everything else is possible.
break;
}
free_r = free_r->next_from_free_list();
}
guarantee(_free_region_list_size == free_region_list_length(), "Inv");
// If we didn't do an assertion...
return true;
}
size_t G1CollectedHeap::free_region_list_length() {
assert(ZF_mon->owned_by_self(), "precondition.");
size_t len = 0;
HeapRegion* cur = _free_region_list;
while (cur != NULL) {
len++;
cur = cur->next_from_free_list();
}
return len;
}
size_t G1CollectedHeap::unclean_region_list_length() {
assert(ZF_mon->owned_by_self(), "precondition.");
return _unclean_region_list.length();
}
size_t G1CollectedHeap::n_regions() {
return _hrs->length();
}
size_t G1CollectedHeap::max_regions() {
return
(size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
HeapRegion::GrainBytes;
}
size_t G1CollectedHeap::free_regions() {
/* Possibly-expensive assert.
assert(_free_regions == count_free_regions(),
"_free_regions is off.");
*/
return _free_regions;
}
bool G1CollectedHeap::should_zf() {
return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
}
class RegionCounter: public HeapRegionClosure {
size_t _n;
public:
RegionCounter() : _n(0) {}
bool doHeapRegion(HeapRegion* r) {
if (r->is_empty()) {
assert(!r->isHumongous(), "H regions should not be empty.");
_n++;
}
return false;
}
int res() { return (int) _n; }
};
size_t G1CollectedHeap::count_free_regions() {
RegionCounter rc;
heap_region_iterate(&rc);
size_t n = rc.res();
if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
n--;
return n;
}
size_t G1CollectedHeap::count_free_regions_list() {
size_t n = 0;
size_t o = 0;
ZF_mon->lock_without_safepoint_check();
HeapRegion* cur = _free_region_list;
while (cur != NULL) {
cur = cur->next_from_free_list();
n++;
}
size_t m = unclean_region_list_length();
ZF_mon->unlock();
return n + m;
}
bool G1CollectedHeap::should_set_young_locked() {
assert(heap_lock_held_for_gc(),
"the heap lock should already be held by or for this thread");
return (g1_policy()->in_young_gc_mode() &&
g1_policy()->should_add_next_region_to_young_list());
}
void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
assert(heap_lock_held_for_gc(),
"the heap lock should already be held by or for this thread");
_young_list->push_region(hr);
g1_policy()->set_region_short_lived(hr);
}
class NoYoungRegionsClosure: public HeapRegionClosure {
private:
bool _success;
public:
NoYoungRegionsClosure() : _success(true) { }
bool doHeapRegion(HeapRegion* r) {
if (r->is_young()) {
gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
r->bottom(), r->end());
_success = false;
}
return false;
}
bool success() { return _success; }
};
bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
bool check_sample) {
bool ret = true;
ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
if (!ignore_scan_only_list) {
NoYoungRegionsClosure closure;
heap_region_iterate(&closure);
ret = ret && closure.success();
}
return ret;
}
void G1CollectedHeap::empty_young_list() {
assert(heap_lock_held_for_gc(),
"the heap lock should already be held by or for this thread");
assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
_young_list->empty_list();
}
bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
bool no_allocs = true;
for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
HeapRegion* r = _gc_alloc_regions[ap];
no_allocs = r == NULL || r->saved_mark_at_top();
}
return no_allocs;
}
void G1CollectedHeap::retire_all_alloc_regions() {
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
HeapRegion* r = _gc_alloc_regions[ap];
if (r != NULL) {
// Check for aliases.
bool has_processed_alias = false;
for (int i = 0; i < ap; ++i) {
if (_gc_alloc_regions[i] == r) {
has_processed_alias = true;
break;
}
}
if (!has_processed_alias) {
retire_alloc_region(r, false /* par */);
}
}
}
}
// Done at the start of full GC.
void G1CollectedHeap::tear_down_region_lists() {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
while (pop_unclean_region_list_locked() != NULL) ;
assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
"Postconditions of loop.")
while (pop_free_region_list_locked() != NULL) ;
assert(_free_region_list == NULL, "Postcondition of loop.");
if (_free_region_list_size != 0) {
gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
print_on(gclog_or_tty, true /* extended */);
}
assert(_free_region_list_size == 0, "Postconditions of loop.");
}
class RegionResetter: public HeapRegionClosure {
G1CollectedHeap* _g1;
int _n;
public:
RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
bool doHeapRegion(HeapRegion* r) {
if (r->continuesHumongous()) return false;
if (r->top() > r->bottom()) {
if (r->top() < r->end()) {
Copy::fill_to_words(r->top(),
pointer_delta(r->end(), r->top()));
}
r->set_zero_fill_allocated();
} else {
assert(r->is_empty(), "tautology");
_n++;
switch (r->zero_fill_state()) {
case HeapRegion::NotZeroFilled:
case HeapRegion::ZeroFilling:
_g1->put_region_on_unclean_list_locked(r);
break;
case HeapRegion::Allocated:
r->set_zero_fill_complete();
// no break; go on to put on free list.
case HeapRegion::ZeroFilled:
_g1->put_free_region_on_list_locked(r);
break;
}
}
return false;
}
int getFreeRegionCount() {return _n;}
};
// Done at the end of full GC.
void G1CollectedHeap::rebuild_region_lists() {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
// This needs to go at the end of the full GC.
RegionResetter rs;
heap_region_iterate(&rs);
_free_regions = rs.getFreeRegionCount();
// Tell the ZF thread it may have work to do.
if (should_zf()) ZF_mon->notify_all();
}
class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
G1CollectedHeap* _g1;
int _n;
public:
UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
bool doHeapRegion(HeapRegion* r) {
if (r->continuesHumongous()) return false;
if (r->top() > r->bottom()) {
// There are assertions in "set_zero_fill_needed()" below that
// require top() == bottom(), so this is technically illegal.
// We'll skirt the law here, by making that true temporarily.
DEBUG_ONLY(HeapWord* save_top = r->top();
r->set_top(r->bottom()));
r->set_zero_fill_needed();
DEBUG_ONLY(r->set_top(save_top));
}
return false;
}
};
// Done at the start of full GC.
void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
// This needs to go at the end of the full GC.
UsedRegionsNeedZeroFillSetter rs;
heap_region_iterate(&rs);
}
void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
_refine_cte_cl->set_concurrent(concurrent);
}
#ifndef PRODUCT
class PrintHeapRegionClosure: public HeapRegionClosure {
public:
bool doHeapRegion(HeapRegion *r) {
gclog_or_tty->print("Region: "PTR_FORMAT":", r);
if (r != NULL) {
if (r->is_on_free_list())
gclog_or_tty->print("Free ");
if (r->is_young())
gclog_or_tty->print("Young ");
if (r->isHumongous())
gclog_or_tty->print("Is Humongous ");
r->print();
}
return false;
}
};
class SortHeapRegionClosure : public HeapRegionClosure {
size_t young_regions,free_regions, unclean_regions;
size_t hum_regions, count;
size_t unaccounted, cur_unclean, cur_alloc;
size_t total_free;
HeapRegion* cur;
public:
SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
free_regions(0), unclean_regions(0),
hum_regions(0),
count(0), unaccounted(0),
cur_alloc(0), total_free(0)
{}
bool doHeapRegion(HeapRegion *r) {
count++;
if (r->is_on_free_list()) free_regions++;
else if (r->is_on_unclean_list()) unclean_regions++;
else if (r->isHumongous()) hum_regions++;
else if (r->is_young()) young_regions++;
else if (r == cur) cur_alloc++;
else unaccounted++;
return false;
}
void print() {
total_free = free_regions + unclean_regions;
gclog_or_tty->print("%d regions\n", count);
gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
total_free, free_regions, unclean_regions);
gclog_or_tty->print("%d humongous %d young\n",
hum_regions, young_regions);
gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
}
};
void G1CollectedHeap::print_region_counts() {
SortHeapRegionClosure sc(_cur_alloc_region);
PrintHeapRegionClosure cl;
heap_region_iterate(&cl);
heap_region_iterate(&sc);
sc.print();
print_region_accounting_info();
};
bool G1CollectedHeap::regions_accounted_for() {
// TODO: regions accounting for young/survivor/tenured
return true;
}
bool G1CollectedHeap::print_region_accounting_info() {
gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
free_regions(),
count_free_regions(), count_free_regions_list(),
_free_region_list_size, _unclean_region_list.sz());
gclog_or_tty->print_cr("cur_alloc: %d.",
(_cur_alloc_region == NULL ? 0 : 1));
gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
// TODO: check regions accounting for young/survivor/tenured
return true;
}
bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
HeapRegion* hr = heap_region_containing(p);
if (hr == NULL) {
return is_in_permanent(p);
} else {
return hr->is_in(p);
}
}
#endif // PRODUCT
void G1CollectedHeap::g1_unimplemented() {
// Unimplemented();
}