363 lines
15 KiB
C++
363 lines
15 KiB
C++
/*
|
|
* Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
|
|
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
*
|
|
* This code is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 only, as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This code is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
* version 2 for more details (a copy is included in the LICENSE file that
|
|
* accompanied this code).
|
|
*
|
|
* You should have received a copy of the GNU General Public License version
|
|
* 2 along with this work; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*
|
|
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
|
|
* or visit www.oracle.com if you need additional information or have any
|
|
* questions.
|
|
*
|
|
*/
|
|
|
|
#ifndef SHARE_GC_G1_G1COLLECTIONSET_HPP
|
|
#define SHARE_GC_G1_G1COLLECTIONSET_HPP
|
|
|
|
#include "utilities/debug.hpp"
|
|
#include "utilities/globalDefinitions.hpp"
|
|
|
|
class G1CollectedHeap;
|
|
class G1CollectionSetCandidates;
|
|
class G1CollectorState;
|
|
class G1GCPhaseTimes;
|
|
class G1ParScanThreadStateSet;
|
|
class G1Policy;
|
|
class G1SurvivorRegions;
|
|
class HeapRegion;
|
|
class HeapRegionClaimer;
|
|
class HeapRegionClosure;
|
|
|
|
// The collection set.
|
|
//
|
|
// The set of regions that are evacuated during an evacuation pause.
|
|
//
|
|
// At the end of a collection, before freeing the collection set, this set
|
|
// contains all regions that were evacuated during this collection:
|
|
//
|
|
// - survivor regions from the last collection (if any)
|
|
// - eden regions allocated by the mutator
|
|
// - old gen regions evacuated during mixed gc
|
|
//
|
|
// This set is built incrementally at mutator time as regions are retired, and
|
|
// if this had been a mixed gc, some additional (during gc) incrementally added
|
|
// old regions from the collection set candidates built during the concurrent
|
|
// cycle.
|
|
//
|
|
// A more detailed overview of how the collection set changes over time follows:
|
|
//
|
|
// 0) at the end of GC the survivor regions are added to this collection set.
|
|
// 1) the mutator incrementally adds eden regions as they retire
|
|
//
|
|
// ----- gc starts
|
|
//
|
|
// 2) prepare (finalize) young regions of the collection set for collection
|
|
// - relabel the survivors as eden
|
|
// - finish up the incremental building that happened at mutator time
|
|
//
|
|
// iff this is a young-only collection:
|
|
//
|
|
// a3) evacuate the current collection set in one "initial evacuation" phase
|
|
//
|
|
// iff this is a mixed collection:
|
|
//
|
|
// b3) calculate the set of old gen regions we may be able to collect in this
|
|
// collection from the list of collection set candidates.
|
|
// - one part is added to the current collection set
|
|
// - the remainder regions are labeled as optional, and NOT yet added to the
|
|
// collection set.
|
|
// b4) evacuate the current collection set in the "initial evacuation" phase
|
|
// b5) evacuate the optional regions in the "optional evacuation" phase. This is
|
|
// done in increments (or rounds).
|
|
// b5-1) add a few of the optional regions to the current collection set
|
|
// b5-2) evacuate only these newly added optional regions. For this mechanism we
|
|
// reuse the incremental collection set building infrastructure (used also at
|
|
// mutator time).
|
|
// b5-3) repeat from b5-1 until the policy determines we are done
|
|
//
|
|
// all collections
|
|
//
|
|
// 6) free the collection set (contains all regions now; empties collection set
|
|
// afterwards)
|
|
// 7) add survivors to this collection set
|
|
//
|
|
// ----- gc ends
|
|
//
|
|
// goto 1)
|
|
//
|
|
// Examples of how the collection set might look over time:
|
|
//
|
|
// Legend:
|
|
// S = survivor, E = eden, O = old.
|
|
// |xxxx| = increment (with increment markers), containing four regions
|
|
//
|
|
// |SSSS| ... after step 0), with four survivor regions
|
|
// |SSSSEE| ... at step 1), after retiring two eden regions
|
|
// |SSSSEEEE| ... after step 1), after retiring four eden regions
|
|
// |EEEEEEEE| ... after step 2)
|
|
//
|
|
// iff this is a young-only collection
|
|
//
|
|
// EEEEEEEE|| ... after step a3), after initial evacuation phase
|
|
// || ... after step 6)
|
|
// |SS| ... after step 7), with two survivor regions
|
|
//
|
|
// iff this is a mixed collection
|
|
//
|
|
// |EEEEEEEEOOOO| ... after step b3), added four regions to be
|
|
// evacuated in the "initial evacuation" phase
|
|
// EEEEEEEEOOOO|| ... after step b4), incremental part is empty
|
|
// after evacuation
|
|
// EEEEEEEEOOOO|OO| ... after step b5.1), added two regions to be
|
|
// evacuated in the first round of the
|
|
// "optional evacuation" phase
|
|
// EEEEEEEEOOOOOO|O| ... after step b5.1), added one region to be
|
|
// evacuated in the second round of the
|
|
// "optional evacuation" phase
|
|
// EEEEEEEEOOOOOOO|| ... after step b5), the complete collection set.
|
|
// || ... after step b6)
|
|
// |SSS| ... after step 7), with three survivor regions
|
|
//
|
|
class G1CollectionSet {
|
|
G1CollectedHeap* _g1h;
|
|
G1Policy* _policy;
|
|
|
|
// All old gen collection set candidate regions for the current mixed phase.
|
|
G1CollectionSetCandidates* _candidates;
|
|
|
|
uint _eden_region_length;
|
|
uint _survivor_region_length;
|
|
uint _old_region_length;
|
|
|
|
// The actual collection set as a set of region indices.
|
|
// All entries in _collection_set_regions below _collection_set_cur_length are
|
|
// assumed to be part of the collection set.
|
|
// We assume that at any time there is at most only one writer and (one or more)
|
|
// concurrent readers. This means we are good with using storestore and loadload
|
|
// barriers on the writer and reader respectively only.
|
|
uint* _collection_set_regions;
|
|
volatile size_t _collection_set_cur_length;
|
|
size_t _collection_set_max_length;
|
|
|
|
// When doing mixed collections we can add old regions to the collection set, which
|
|
// will be collected only if there is enough time. We call these optional regions.
|
|
// This member records the current number of regions that are of that type that
|
|
// correspond to the first x entries in the collection set candidates.
|
|
uint _num_optional_regions;
|
|
|
|
// The number of bytes in the collection set before the pause. Set from
|
|
// the incrementally built collection set at the start of an evacuation
|
|
// pause, and updated as more regions are added to the collection set.
|
|
size_t _bytes_used_before;
|
|
|
|
// The number of cards in the remembered set in the collection set. Set from
|
|
// the incrementally built collection set at the start of an evacuation
|
|
// pause, and updated as more regions are added to the collection set.
|
|
size_t _recorded_rs_length;
|
|
|
|
enum CSetBuildType {
|
|
Active, // We are actively building the collection set
|
|
Inactive // We are not actively building the collection set
|
|
};
|
|
|
|
CSetBuildType _inc_build_state;
|
|
size_t _inc_part_start;
|
|
|
|
// Information about eden regions in the incremental collection set.
|
|
struct IncCollectionSetRegionStat {
|
|
// The predicted non-copy time that was added to the total incremental value
|
|
// for the collection set.
|
|
double _non_copy_time_ms;
|
|
// The remembered set length that was added to the total incremental value
|
|
// for the collection set.
|
|
size_t _rs_length;
|
|
|
|
#ifdef ASSERT
|
|
// Resets members to "uninitialized" values.
|
|
void reset() { _rs_length = ~(size_t)0; _non_copy_time_ms = -1.0; }
|
|
#endif
|
|
};
|
|
|
|
IncCollectionSetRegionStat* _inc_collection_set_stats;
|
|
// The associated information that is maintained while the incremental
|
|
// collection set is being built with *young* regions. Used to populate
|
|
// the recorded info for the evacuation pause.
|
|
|
|
// The number of bytes in the incrementally built collection set.
|
|
// Used to set _collection_set_bytes_used_before at the start of
|
|
// an evacuation pause.
|
|
size_t _inc_bytes_used_before;
|
|
|
|
// The RSet lengths recorded for regions in the CSet. It is updated
|
|
// by the thread that adds a new region to the CSet. We assume that
|
|
// only one thread can be allocating a new CSet region (currently,
|
|
// it does so after taking the Heap_lock) hence no need to
|
|
// synchronize updates to this field.
|
|
size_t _inc_recorded_rs_length;
|
|
|
|
// A concurrent refinement thread periodically samples the young
|
|
// region RSets and needs to update _inc_recorded_rs_length as
|
|
// the RSets grow. Instead of having to synchronize updates to that
|
|
// field we accumulate them in this field and add it to
|
|
// _inc_recorded_rs_length_diff at the start of a GC.
|
|
size_t _inc_recorded_rs_length_diff;
|
|
|
|
// The predicted elapsed time it will take to collect the regions in
|
|
// the CSet. This is updated by the thread that adds a new region to
|
|
// the CSet. See the comment for _inc_recorded_rs_length about
|
|
// MT-safety assumptions.
|
|
double _inc_predicted_non_copy_time_ms;
|
|
|
|
// See the comment for _inc_recorded_rs_length_diff.
|
|
double _inc_predicted_non_copy_time_ms_diff;
|
|
|
|
void set_recorded_rs_length(size_t rs_length);
|
|
|
|
G1CollectorState* collector_state() const;
|
|
G1GCPhaseTimes* phase_times();
|
|
|
|
void verify_young_cset_indices() const NOT_DEBUG_RETURN;
|
|
|
|
double predict_region_non_copy_time_ms(HeapRegion* hr) const;
|
|
|
|
// Update the incremental collection set information when adding a region.
|
|
void add_young_region_common(HeapRegion* hr);
|
|
|
|
// Add old region "hr" to the collection set.
|
|
void add_old_region(HeapRegion* hr);
|
|
void free_optional_regions();
|
|
|
|
// Add old region "hr" to optional collection set.
|
|
void add_optional_region(HeapRegion* hr);
|
|
|
|
void move_candidates_to_collection_set(uint num_regions);
|
|
|
|
// Finalize the young part of the initial collection set. Relabel survivor regions
|
|
// as Eden and calculate a prediction on how long the evacuation of all young regions
|
|
// will take.
|
|
double finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors);
|
|
// Perform any final calculations on the incremental collection set fields before we
|
|
// can use them.
|
|
void finalize_incremental_building();
|
|
|
|
// Select the old regions of the initial collection set and determine how many optional
|
|
// regions we might be able to evacuate in this pause.
|
|
void finalize_old_part(double time_remaining_ms);
|
|
|
|
// Iterate the part of the collection set given by the offset and length applying the given
|
|
// HeapRegionClosure. The worker_id will determine where in the part to start the iteration
|
|
// to allow for more efficient parallel iteration.
|
|
void iterate_part_from(HeapRegionClosure* cl,
|
|
HeapRegionClaimer* hr_claimer,
|
|
size_t offset,
|
|
size_t length,
|
|
uint worker_id,
|
|
uint total_workers) const;
|
|
public:
|
|
G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy);
|
|
~G1CollectionSet();
|
|
|
|
// Initializes the collection set giving the maximum possible length of the collection set.
|
|
void initialize(uint max_region_length);
|
|
|
|
void clear_candidates();
|
|
|
|
void set_candidates(G1CollectionSetCandidates* candidates) {
|
|
assert(_candidates == NULL, "Trying to replace collection set candidates.");
|
|
_candidates = candidates;
|
|
}
|
|
G1CollectionSetCandidates* candidates() { return _candidates; }
|
|
|
|
void init_region_lengths(uint eden_cset_region_length,
|
|
uint survivor_cset_region_length);
|
|
|
|
uint region_length() const { return young_region_length() +
|
|
old_region_length(); }
|
|
uint young_region_length() const { return eden_region_length() +
|
|
survivor_region_length(); }
|
|
|
|
uint eden_region_length() const { return _eden_region_length; }
|
|
uint survivor_region_length() const { return _survivor_region_length; }
|
|
uint old_region_length() const { return _old_region_length; }
|
|
uint optional_region_length() const { return _num_optional_regions; }
|
|
|
|
// Reset the contents of the collection set.
|
|
void clear();
|
|
|
|
// Incremental collection set support
|
|
|
|
// Initialize incremental collection set info.
|
|
void start_incremental_building();
|
|
// Start a new collection set increment.
|
|
void update_incremental_marker() { _inc_build_state = Active; _inc_part_start = _collection_set_cur_length; }
|
|
// Stop adding regions to the current collection set increment.
|
|
void stop_incremental_building() { _inc_build_state = Inactive; }
|
|
|
|
// Iterate over the current collection set increment applying the given HeapRegionClosure
|
|
// from a starting position determined by the given worker id.
|
|
void iterate_incremental_part_from(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id, uint total_workers) const;
|
|
|
|
// Returns the length of the current increment in number of regions.
|
|
size_t increment_length() const { return _collection_set_cur_length - _inc_part_start; }
|
|
// Returns the length of the whole current collection set in number of regions
|
|
size_t cur_length() const { return _collection_set_cur_length; }
|
|
|
|
// Iterate over the entire collection set (all increments calculated so far), applying
|
|
// the given HeapRegionClosure on all of them.
|
|
void iterate(HeapRegionClosure* cl) const;
|
|
void par_iterate(HeapRegionClosure* cl,
|
|
HeapRegionClaimer* hr_claimer,
|
|
uint worker_id,
|
|
uint total_workers) const;
|
|
|
|
void iterate_optional(HeapRegionClosure* cl) const;
|
|
|
|
size_t recorded_rs_length() { return _recorded_rs_length; }
|
|
|
|
size_t bytes_used_before() const {
|
|
return _bytes_used_before;
|
|
}
|
|
|
|
void reset_bytes_used_before() {
|
|
_bytes_used_before = 0;
|
|
}
|
|
|
|
// Finalize the initial collection set consisting of all young regions potentially a
|
|
// few old gen regions.
|
|
void finalize_initial_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor);
|
|
// Finalize the next collection set from the set of available optional old gen regions.
|
|
bool finalize_optional_for_evacuation(double remaining_pause_time);
|
|
// Abandon (clean up) optional collection set regions that were not evacuated in this
|
|
// pause.
|
|
void abandon_optional_collection_set(G1ParScanThreadStateSet* pss);
|
|
|
|
// Update information about hr in the aggregated information for
|
|
// the incrementally built collection set.
|
|
void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);
|
|
|
|
// Add eden region to the collection set.
|
|
void add_eden_region(HeapRegion* hr);
|
|
|
|
// Add survivor region to the collection set.
|
|
void add_survivor_regions(HeapRegion* hr);
|
|
|
|
#ifndef PRODUCT
|
|
bool verify_young_ages();
|
|
|
|
void print(outputStream* st);
|
|
#endif // !PRODUCT
|
|
};
|
|
|
|
#endif // SHARE_GC_G1_G1COLLECTIONSET_HPP
|