7118202: G1: eden size unnecessarily drops to a minimum
Summary: An integer underflow can cause the RSet lengths to be massively overpredicted which forces the eden size to the minimum.
Reviewed-by: brutisso, johnc
/*
* Copyright (c) 2001, 2011, 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.
*
*/
#include "precompiled.hpp"
#include "gc_implementation/g1/concurrentG1Refine.hpp"
#include "gc_implementation/g1/concurrentMark.hpp"
#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
#include "gc_implementation/g1/g1CollectorPolicy.hpp"
#include "gc_implementation/g1/g1ErgoVerbose.hpp"
#include "gc_implementation/g1/heapRegionRemSet.hpp"
#include "gc_implementation/shared/gcPolicyCounters.hpp"
#include "runtime/arguments.hpp"
#include "runtime/java.hpp"
#include "runtime/mutexLocker.hpp"
#include "utilities/debug.hpp"
// Different defaults for different number of GC threads
// They were chosen by running GCOld and SPECjbb on debris with different
// numbers of GC threads and choosing them based on the results
// all the same
static double rs_length_diff_defaults[] = {
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
};
static double cost_per_card_ms_defaults[] = {
0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
};
// all the same
static double fully_young_cards_per_entry_ratio_defaults[] = {
1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
};
static double cost_per_entry_ms_defaults[] = {
0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
};
static double cost_per_byte_ms_defaults[] = {
0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
};
// these should be pretty consistent
static double constant_other_time_ms_defaults[] = {
5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
};
static double young_other_cost_per_region_ms_defaults[] = {
0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
};
static double non_young_other_cost_per_region_ms_defaults[] = {
1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
};
// Help class for avoiding interleaved logging
class LineBuffer: public StackObj {
private:
static const int BUFFER_LEN = 1024;
static const int INDENT_CHARS = 3;
char _buffer[BUFFER_LEN];
int _indent_level;
int _cur;
void vappend(const char* format, va_list ap) {
int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
if (res != -1) {
_cur += res;
} else {
DEBUG_ONLY(warning("buffer too small in LineBuffer");)
_buffer[BUFFER_LEN -1] = 0;
_cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
}
}
public:
explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
_buffer[_cur] = ' ';
}
}
#ifndef PRODUCT
~LineBuffer() {
assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
}
#endif
void append(const char* format, ...) {
va_list ap;
va_start(ap, format);
vappend(format, ap);
va_end(ap);
}
void append_and_print_cr(const char* format, ...) {
va_list ap;
va_start(ap, format);
vappend(format, ap);
va_end(ap);
gclog_or_tty->print_cr("%s", _buffer);
_cur = _indent_level * INDENT_CHARS;
}
};
G1CollectorPolicy::G1CollectorPolicy() :
_parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
? ParallelGCThreads : 1),
_recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_all_pause_times_ms(new NumberSeq()),
_stop_world_start(0.0),
_all_stop_world_times_ms(new NumberSeq()),
_all_yield_times_ms(new NumberSeq()),
_using_new_ratio_calculations(false),
_summary(new Summary()),
_cur_clear_ct_time_ms(0.0),
_mark_closure_time_ms(0.0),
_cur_ref_proc_time_ms(0.0),
_cur_ref_enq_time_ms(0.0),
#ifndef PRODUCT
_min_clear_cc_time_ms(-1.0),
_max_clear_cc_time_ms(-1.0),
_cur_clear_cc_time_ms(0.0),
_cum_clear_cc_time_ms(0.0),
_num_cc_clears(0L),
#endif
_aux_num(10),
_all_aux_times_ms(new NumberSeq[_aux_num]),
_cur_aux_start_times_ms(new double[_aux_num]),
_cur_aux_times_ms(new double[_aux_num]),
_cur_aux_times_set(new bool[_aux_num]),
_concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_prev_collection_pause_end_ms(0.0),
_pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
_partially_young_cards_per_entry_ratio_seq(
new TruncatedSeq(TruncatedSeqLength)),
_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
_constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_non_young_other_cost_per_region_ms_seq(
new TruncatedSeq(TruncatedSeqLength)),
_pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
_rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
_pause_time_target_ms((double) MaxGCPauseMillis),
_full_young_gcs(true),
_full_young_pause_num(0),
_partial_young_pause_num(0),
_during_marking(false),
_in_marking_window(false),
_in_marking_window_im(false),
_known_garbage_ratio(0.0),
_known_garbage_bytes(0),
_young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
_recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_avg_pause_time_ratio(0.0),
_all_full_gc_times_ms(new NumberSeq()),
_initiate_conc_mark_if_possible(false),
_during_initial_mark_pause(false),
_should_revert_to_full_young_gcs(false),
_last_full_young_gc(false),
_eden_bytes_before_gc(0),
_survivor_bytes_before_gc(0),
_capacity_before_gc(0),
_prev_collection_pause_used_at_end_bytes(0),
_eden_cset_region_length(0),
_survivor_cset_region_length(0),
_old_cset_region_length(0),
_collection_set(NULL),
_collection_set_bytes_used_before(0),
// Incremental CSet attributes
_inc_cset_build_state(Inactive),
_inc_cset_head(NULL),
_inc_cset_tail(NULL),
_inc_cset_bytes_used_before(0),
_inc_cset_max_finger(NULL),
_inc_cset_recorded_rs_lengths(0),
_inc_cset_predicted_elapsed_time_ms(0.0),
#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
_short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
G1YoungSurvRateNumRegionsSummary)),
_survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
G1YoungSurvRateNumRegionsSummary)),
// add here any more surv rate groups
_recorded_survivor_regions(0),
_recorded_survivor_head(NULL),
_recorded_survivor_tail(NULL),
_survivors_age_table(true),
_gc_overhead_perc(0.0) {
// Set up the region size and associated fields. Given that the
// policy is created before the heap, we have to set this up here,
// so it's done as soon as possible.
HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
HeapRegionRemSet::setup_remset_size();
G1ErgoVerbose::initialize();
if (PrintAdaptiveSizePolicy) {
// Currently, we only use a single switch for all the heuristics.
G1ErgoVerbose::set_enabled(true);
// Given that we don't currently have a verboseness level
// parameter, we'll hardcode this to high. This can be easily
// changed in the future.
G1ErgoVerbose::set_level(ErgoHigh);
} else {
G1ErgoVerbose::set_enabled(false);
}
// Verify PLAB sizes
const size_t region_size = HeapRegion::GrainWords;
if (YoungPLABSize > region_size || OldPLABSize > region_size) {
char buffer[128];
jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
OldPLABSize > region_size ? "Old" : "Young", region_size);
vm_exit_during_initialization(buffer);
}
_recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
_prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
_par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
_par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
_par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
_par_last_update_rs_times_ms = new double[_parallel_gc_threads];
_par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
_par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
_par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
_par_last_termination_times_ms = new double[_parallel_gc_threads];
_par_last_termination_attempts = new double[_parallel_gc_threads];
_par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
_par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
_par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
// start conservatively
_expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
int index;
if (ParallelGCThreads == 0)
index = 0;
else if (ParallelGCThreads > 8)
index = 7;
else
index = ParallelGCThreads - 1;
_pending_card_diff_seq->add(0.0);
_rs_length_diff_seq->add(rs_length_diff_defaults[index]);
_cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
_fully_young_cards_per_entry_ratio_seq->add(
fully_young_cards_per_entry_ratio_defaults[index]);
_cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
_cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
_constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
_young_other_cost_per_region_ms_seq->add(
young_other_cost_per_region_ms_defaults[index]);
_non_young_other_cost_per_region_ms_seq->add(
non_young_other_cost_per_region_ms_defaults[index]);
// Below, we might need to calculate the pause time target based on
// the pause interval. When we do so we are going to give G1 maximum
// flexibility and allow it to do pauses when it needs to. So, we'll
// arrange that the pause interval to be pause time target + 1 to
// ensure that a) the pause time target is maximized with respect to
// the pause interval and b) we maintain the invariant that pause
// time target < pause interval. If the user does not want this
// maximum flexibility, they will have to set the pause interval
// explicitly.
// First make sure that, if either parameter is set, its value is
// reasonable.
if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
if (MaxGCPauseMillis < 1) {
vm_exit_during_initialization("MaxGCPauseMillis should be "
"greater than 0");
}
}
if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
if (GCPauseIntervalMillis < 1) {
vm_exit_during_initialization("GCPauseIntervalMillis should be "
"greater than 0");
}
}
// Then, if the pause time target parameter was not set, set it to
// the default value.
if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
// The default pause time target in G1 is 200ms
FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
} else {
// We do not allow the pause interval to be set without the
// pause time target
vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
"without setting MaxGCPauseMillis");
}
}
// Then, if the interval parameter was not set, set it according to
// the pause time target (this will also deal with the case when the
// pause time target is the default value).
if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
}
// Finally, make sure that the two parameters are consistent.
if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
char buffer[256];
jio_snprintf(buffer, 256,
"MaxGCPauseMillis (%u) should be less than "
"GCPauseIntervalMillis (%u)",
MaxGCPauseMillis, GCPauseIntervalMillis);
vm_exit_during_initialization(buffer);
}
double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
double time_slice = (double) GCPauseIntervalMillis / 1000.0;
_mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
_sigma = (double) G1ConfidencePercent / 100.0;
// start conservatively (around 50ms is about right)
_concurrent_mark_remark_times_ms->add(0.05);
_concurrent_mark_cleanup_times_ms->add(0.20);
_tenuring_threshold = MaxTenuringThreshold;
// _max_survivor_regions will be calculated by
// update_young_list_target_length() during initialization.
_max_survivor_regions = 0;
assert(GCTimeRatio > 0,
"we should have set it to a default value set_g1_gc_flags() "
"if a user set it to 0");
_gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
uintx reserve_perc = G1ReservePercent;
// Put an artificial ceiling on this so that it's not set to a silly value.
if (reserve_perc > 50) {
reserve_perc = 50;
warning("G1ReservePercent is set to a value that is too large, "
"it's been updated to %u", reserve_perc);
}
_reserve_factor = (double) reserve_perc / 100.0;
// This will be set when the heap is expanded
// for the first time during initialization.
_reserve_regions = 0;
initialize_all();
_collectionSetChooser = new CollectionSetChooser();
}
// Increment "i", mod "len"
static void inc_mod(int& i, int len) {
i++; if (i == len) i = 0;
}
void G1CollectorPolicy::initialize_flags() {
set_min_alignment(HeapRegion::GrainBytes);
set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
if (SurvivorRatio < 1) {
vm_exit_during_initialization("Invalid survivor ratio specified");
}
CollectorPolicy::initialize_flags();
}
// The easiest way to deal with the parsing of the NewSize /
// MaxNewSize / etc. parameteres is to re-use the code in the
// TwoGenerationCollectorPolicy class. This is similar to what
// ParallelScavenge does with its GenerationSizer class (see
// ParallelScavengeHeap::initialize()). We might change this in the
// future, but it's a good start.
class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
private:
size_t size_to_region_num(size_t byte_size) {
return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
}
public:
G1YoungGenSizer() {
initialize_flags();
initialize_size_info();
}
size_t min_young_region_num() {
return size_to_region_num(_min_gen0_size);
}
size_t initial_young_region_num() {
return size_to_region_num(_initial_gen0_size);
}
size_t max_young_region_num() {
return size_to_region_num(_max_gen0_size);
}
};
void G1CollectorPolicy::update_young_list_size_using_newratio(size_t number_of_heap_regions) {
assert(number_of_heap_regions > 0, "Heap must be initialized");
size_t young_size = number_of_heap_regions / (NewRatio + 1);
_min_desired_young_length = young_size;
_max_desired_young_length = young_size;
}
void G1CollectorPolicy::init() {
// Set aside an initial future to_space.
_g1 = G1CollectedHeap::heap();
assert(Heap_lock->owned_by_self(), "Locking discipline.");
initialize_gc_policy_counters();
G1YoungGenSizer sizer;
_min_desired_young_length = sizer.min_young_region_num();
_max_desired_young_length = sizer.max_young_region_num();
if (FLAG_IS_CMDLINE(NewRatio)) {
if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
} else {
// Treat NewRatio as a fixed size that is only recalculated when the heap size changes
update_young_list_size_using_newratio(_g1->n_regions());
_using_new_ratio_calculations = true;
}
}
assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
set_adaptive_young_list_length(_min_desired_young_length < _max_desired_young_length);
if (adaptive_young_list_length()) {
_young_list_fixed_length = 0;
} else {
assert(_min_desired_young_length == _max_desired_young_length, "Min and max young size differ");
_young_list_fixed_length = _min_desired_young_length;
}
_free_regions_at_end_of_collection = _g1->free_regions();
update_young_list_target_length();
_prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
// We may immediately start allocating regions and placing them on the
// collection set list. Initialize the per-collection set info
start_incremental_cset_building();
}
// Create the jstat counters for the policy.
void G1CollectorPolicy::initialize_gc_policy_counters() {
_gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
}
bool G1CollectorPolicy::predict_will_fit(size_t young_length,
double base_time_ms,
size_t base_free_regions,
double target_pause_time_ms) {
if (young_length >= base_free_regions) {
// end condition 1: not enough space for the young regions
return false;
}
double accum_surv_rate = accum_yg_surv_rate_pred((int)(young_length - 1));
size_t bytes_to_copy =
(size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
double young_other_time_ms = predict_young_other_time_ms(young_length);
double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
if (pause_time_ms > target_pause_time_ms) {
// end condition 2: prediction is over the target pause time
return false;
}
size_t free_bytes =
(base_free_regions - young_length) * HeapRegion::GrainBytes;
if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
// end condition 3: out-of-space (conservatively!)
return false;
}
// success!
return true;
}
void G1CollectorPolicy::record_new_heap_size(size_t new_number_of_regions) {
// re-calculate the necessary reserve
double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
// We use ceiling so that if reserve_regions_d is > 0.0 (but
// smaller than 1.0) we'll get 1.
_reserve_regions = (size_t) ceil(reserve_regions_d);
if (_using_new_ratio_calculations) {
// -XX:NewRatio was specified so we need to update the
// young gen length when the heap size has changed.
update_young_list_size_using_newratio(new_number_of_regions);
}
}
size_t G1CollectorPolicy::calculate_young_list_desired_min_length(
size_t base_min_length) {
size_t desired_min_length = 0;
if (adaptive_young_list_length()) {
if (_alloc_rate_ms_seq->num() > 3) {
double now_sec = os::elapsedTime();
double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
double alloc_rate_ms = predict_alloc_rate_ms();
desired_min_length = (size_t) ceil(alloc_rate_ms * when_ms);
} else {
// otherwise we don't have enough info to make the prediction
}
}
desired_min_length += base_min_length;
// make sure we don't go below any user-defined minimum bound
return MAX2(_min_desired_young_length, desired_min_length);
}
size_t G1CollectorPolicy::calculate_young_list_desired_max_length() {
// Here, we might want to also take into account any additional
// constraints (i.e., user-defined minimum bound). Currently, we
// effectively don't set this bound.
return _max_desired_young_length;
}
void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
if (rs_lengths == (size_t) -1) {
// if it's set to the default value (-1), we should predict it;
// otherwise, use the given value.
rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
}
// Calculate the absolute and desired min bounds.
// This is how many young regions we already have (currently: the survivors).
size_t base_min_length = recorded_survivor_regions();
// This is the absolute minimum young length, which ensures that we
// can allocate one eden region in the worst-case.
size_t absolute_min_length = base_min_length + 1;
size_t desired_min_length =
calculate_young_list_desired_min_length(base_min_length);
if (desired_min_length < absolute_min_length) {
desired_min_length = absolute_min_length;
}
// Calculate the absolute and desired max bounds.
// We will try our best not to "eat" into the reserve.
size_t absolute_max_length = 0;
if (_free_regions_at_end_of_collection > _reserve_regions) {
absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
}
size_t desired_max_length = calculate_young_list_desired_max_length();
if (desired_max_length > absolute_max_length) {
desired_max_length = absolute_max_length;
}
size_t young_list_target_length = 0;
if (adaptive_young_list_length()) {
if (full_young_gcs()) {
young_list_target_length =
calculate_young_list_target_length(rs_lengths,
base_min_length,
desired_min_length,
desired_max_length);
_rs_lengths_prediction = rs_lengths;
} else {
// Don't calculate anything and let the code below bound it to
// the desired_min_length, i.e., do the next GC as soon as
// possible to maximize how many old regions we can add to it.
}
} else {
if (full_young_gcs()) {
young_list_target_length = _young_list_fixed_length;
} else {
// A bit arbitrary: during partially-young GCs we allocate half
// the young regions to try to add old regions to the CSet.
young_list_target_length = _young_list_fixed_length / 2;
// We choose to accept that we might go under the desired min
// length given that we intentionally ask for a smaller young gen.
desired_min_length = absolute_min_length;
}
}
// Make sure we don't go over the desired max length, nor under the
// desired min length. In case they clash, desired_min_length wins
// which is why that test is second.
if (young_list_target_length > desired_max_length) {
young_list_target_length = desired_max_length;
}
if (young_list_target_length < desired_min_length) {
young_list_target_length = desired_min_length;
}
assert(young_list_target_length > recorded_survivor_regions(),
"we should be able to allocate at least one eden region");
assert(young_list_target_length >= absolute_min_length, "post-condition");
_young_list_target_length = young_list_target_length;
update_max_gc_locker_expansion();
}
size_t
G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
size_t base_min_length,
size_t desired_min_length,
size_t desired_max_length) {
assert(adaptive_young_list_length(), "pre-condition");
assert(full_young_gcs(), "only call this for fully-young GCs");
// In case some edge-condition makes the desired max length too small...
if (desired_max_length <= desired_min_length) {
return desired_min_length;
}
// We'll adjust min_young_length and max_young_length not to include
// the already allocated young regions (i.e., so they reflect the
// min and max eden regions we'll allocate). The base_min_length
// will be reflected in the predictions by the
// survivor_regions_evac_time prediction.
assert(desired_min_length > base_min_length, "invariant");
size_t min_young_length = desired_min_length - base_min_length;
assert(desired_max_length > base_min_length, "invariant");
size_t max_young_length = desired_max_length - base_min_length;
double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
double survivor_regions_evac_time = predict_survivor_regions_evac_time();
size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
double base_time_ms =
predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
survivor_regions_evac_time;
size_t available_free_regions = _free_regions_at_end_of_collection;
size_t base_free_regions = 0;
if (available_free_regions > _reserve_regions) {
base_free_regions = available_free_regions - _reserve_regions;
}
// Here, we will make sure that the shortest young length that
// makes sense fits within the target pause time.
if (predict_will_fit(min_young_length, base_time_ms,
base_free_regions, target_pause_time_ms)) {
// The shortest young length will fit into the target pause time;
// we'll now check whether the absolute maximum number of young
// regions will fit in the target pause time. If not, we'll do
// a binary search between min_young_length and max_young_length.
if (predict_will_fit(max_young_length, base_time_ms,
base_free_regions, target_pause_time_ms)) {
// The maximum young length will fit into the target pause time.
// We are done so set min young length to the maximum length (as
// the result is assumed to be returned in min_young_length).
min_young_length = max_young_length;
} else {
// The maximum possible number of young regions will not fit within
// the target pause time so we'll search for the optimal
// length. The loop invariants are:
//
// min_young_length < max_young_length
// min_young_length is known to fit into the target pause time
// max_young_length is known not to fit into the target pause time
//
// Going into the loop we know the above hold as we've just
// checked them. Every time around the loop we check whether
// the middle value between min_young_length and
// max_young_length fits into the target pause time. If it
// does, it becomes the new min. If it doesn't, it becomes
// the new max. This way we maintain the loop invariants.
assert(min_young_length < max_young_length, "invariant");
size_t diff = (max_young_length - min_young_length) / 2;
while (diff > 0) {
size_t young_length = min_young_length + diff;
if (predict_will_fit(young_length, base_time_ms,
base_free_regions, target_pause_time_ms)) {
min_young_length = young_length;
} else {
max_young_length = young_length;
}
assert(min_young_length < max_young_length, "invariant");
diff = (max_young_length - min_young_length) / 2;
}
// The results is min_young_length which, according to the
// loop invariants, should fit within the target pause time.
// These are the post-conditions of the binary search above:
assert(min_young_length < max_young_length,
"otherwise we should have discovered that max_young_length "
"fits into the pause target and not done the binary search");
assert(predict_will_fit(min_young_length, base_time_ms,
base_free_regions, target_pause_time_ms),
"min_young_length, the result of the binary search, should "
"fit into the pause target");
assert(!predict_will_fit(min_young_length + 1, base_time_ms,
base_free_regions, target_pause_time_ms),
"min_young_length, the result of the binary search, should be "
"optimal, so no larger length should fit into the pause target");
}
} else {
// Even the minimum length doesn't fit into the pause time
// target, return it as the result nevertheless.
}
return base_min_length + min_young_length;
}
double G1CollectorPolicy::predict_survivor_regions_evac_time() {
double survivor_regions_evac_time = 0.0;
for (HeapRegion * r = _recorded_survivor_head;
r != NULL && r != _recorded_survivor_tail->get_next_young_region();
r = r->get_next_young_region()) {
survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
}
return survivor_regions_evac_time;
}
void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
guarantee( adaptive_young_list_length(), "should not call this otherwise" );
size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
if (rs_lengths > _rs_lengths_prediction) {
// add 10% to avoid having to recalculate often
size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
update_young_list_target_length(rs_lengths_prediction);
}
}
HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded) {
guarantee(false, "Not using this policy feature yet.");
return NULL;
}
// This method controls how a collector handles one or more
// of its generations being fully allocated.
HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
bool is_tlab) {
guarantee(false, "Not using this policy feature yet.");
return NULL;
}
#ifndef PRODUCT
bool G1CollectorPolicy::verify_young_ages() {
HeapRegion* head = _g1->young_list()->first_region();
return
verify_young_ages(head, _short_lived_surv_rate_group);
// also call verify_young_ages on any additional surv rate groups
}
bool
G1CollectorPolicy::verify_young_ages(HeapRegion* head,
SurvRateGroup *surv_rate_group) {
guarantee( surv_rate_group != NULL, "pre-condition" );
const char* name = surv_rate_group->name();
bool ret = true;
int prev_age = -1;
for (HeapRegion* curr = head;
curr != NULL;
curr = curr->get_next_young_region()) {
SurvRateGroup* group = curr->surv_rate_group();
if (group == NULL && !curr->is_survivor()) {
gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
ret = false;
}
if (surv_rate_group == group) {
int age = curr->age_in_surv_rate_group();
if (age < 0) {
gclog_or_tty->print_cr("## %s: encountered negative age", name);
ret = false;
}
if (age <= prev_age) {
gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
"(%d, %d)", name, age, prev_age);
ret = false;
}
prev_age = age;
}
}
return ret;
}
#endif // PRODUCT
void G1CollectorPolicy::record_full_collection_start() {
_cur_collection_start_sec = os::elapsedTime();
// Release the future to-space so that it is available for compaction into.
_g1->set_full_collection();
}
void G1CollectorPolicy::record_full_collection_end() {
// Consider this like a collection pause for the purposes of allocation
// since last pause.
double end_sec = os::elapsedTime();
double full_gc_time_sec = end_sec - _cur_collection_start_sec;
double full_gc_time_ms = full_gc_time_sec * 1000.0;
_all_full_gc_times_ms->add(full_gc_time_ms);
update_recent_gc_times(end_sec, full_gc_time_ms);
_g1->clear_full_collection();
// "Nuke" the heuristics that control the fully/partially young GC
// transitions and make sure we start with fully young GCs after the
// Full GC.
set_full_young_gcs(true);
_last_full_young_gc = false;
_should_revert_to_full_young_gcs = false;
clear_initiate_conc_mark_if_possible();
clear_during_initial_mark_pause();
_known_garbage_bytes = 0;
_known_garbage_ratio = 0.0;
_in_marking_window = false;
_in_marking_window_im = false;
_short_lived_surv_rate_group->start_adding_regions();
// also call this on any additional surv rate groups
record_survivor_regions(0, NULL, NULL);
_free_regions_at_end_of_collection = _g1->free_regions();
// Reset survivors SurvRateGroup.
_survivor_surv_rate_group->reset();
update_young_list_target_length();
_collectionSetChooser->updateAfterFullCollection();
}
void G1CollectorPolicy::record_stop_world_start() {
_stop_world_start = os::elapsedTime();
}
void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
size_t start_used) {
if (PrintGCDetails) {
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print("[GC pause");
gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
}
// We only need to do this here as the policy will only be applied
// to the GC we're about to start. so, no point is calculating this
// every time we calculate / recalculate the target young length.
update_survivors_policy();
assert(_g1->used() == _g1->recalculate_used(),
err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
_g1->used(), _g1->recalculate_used()));
double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
_all_stop_world_times_ms->add(s_w_t_ms);
_stop_world_start = 0.0;
_cur_collection_start_sec = start_time_sec;
_cur_collection_pause_used_at_start_bytes = start_used;
_cur_collection_pause_used_regions_at_start = _g1->used_regions();
_pending_cards = _g1->pending_card_num();
_max_pending_cards = _g1->max_pending_card_num();
_bytes_in_collection_set_before_gc = 0;
_bytes_copied_during_gc = 0;
YoungList* young_list = _g1->young_list();
_eden_bytes_before_gc = young_list->eden_used_bytes();
_survivor_bytes_before_gc = young_list->survivor_used_bytes();
_capacity_before_gc = _g1->capacity();
#ifdef DEBUG
// initialise these to something well known so that we can spot
// if they are not set properly
for (int i = 0; i < _parallel_gc_threads; ++i) {
_par_last_gc_worker_start_times_ms[i] = -1234.0;
_par_last_ext_root_scan_times_ms[i] = -1234.0;
_par_last_mark_stack_scan_times_ms[i] = -1234.0;
_par_last_update_rs_times_ms[i] = -1234.0;
_par_last_update_rs_processed_buffers[i] = -1234.0;
_par_last_scan_rs_times_ms[i] = -1234.0;
_par_last_obj_copy_times_ms[i] = -1234.0;
_par_last_termination_times_ms[i] = -1234.0;
_par_last_termination_attempts[i] = -1234.0;
_par_last_gc_worker_end_times_ms[i] = -1234.0;
_par_last_gc_worker_times_ms[i] = -1234.0;
_par_last_gc_worker_other_times_ms[i] = -1234.0;
}
#endif
for (int i = 0; i < _aux_num; ++i) {
_cur_aux_times_ms[i] = 0.0;
_cur_aux_times_set[i] = false;
}
// This is initialized to zero here and is set during
// the evacuation pause if marking is in progress.
_cur_satb_drain_time_ms = 0.0;
_last_young_gc_full = false;
// do that for any other surv rate groups
_short_lived_surv_rate_group->stop_adding_regions();
_survivors_age_table.clear();
assert( verify_young_ages(), "region age verification" );
}
void G1CollectorPolicy::record_concurrent_mark_init_end(double
mark_init_elapsed_time_ms) {
_during_marking = true;
assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
clear_during_initial_mark_pause();
_cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
}
void G1CollectorPolicy::record_concurrent_mark_remark_start() {
_mark_remark_start_sec = os::elapsedTime();
_during_marking = false;
}
void G1CollectorPolicy::record_concurrent_mark_remark_end() {
double end_time_sec = os::elapsedTime();
double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
_concurrent_mark_remark_times_ms->add(elapsed_time_ms);
_cur_mark_stop_world_time_ms += elapsed_time_ms;
_prev_collection_pause_end_ms += elapsed_time_ms;
_mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
}
void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
_mark_cleanup_start_sec = os::elapsedTime();
}
void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
_should_revert_to_full_young_gcs = false;
_last_full_young_gc = true;
_in_marking_window = false;
}
void G1CollectorPolicy::record_concurrent_pause() {
if (_stop_world_start > 0.0) {
double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
_all_yield_times_ms->add(yield_ms);
}
}
void G1CollectorPolicy::record_concurrent_pause_end() {
}
template<class T>
T sum_of(T* sum_arr, int start, int n, int N) {
T sum = (T)0;
for (int i = 0; i < n; i++) {
int j = (start + i) % N;
sum += sum_arr[j];
}
return sum;
}
void G1CollectorPolicy::print_par_stats(int level,
const char* str,
double* data) {
double min = data[0], max = data[0];
double total = 0.0;
LineBuffer buf(level);
buf.append("[%s (ms):", str);
for (uint i = 0; i < no_of_gc_threads(); ++i) {
double val = data[i];
if (val < min)
min = val;
if (val > max)
max = val;
total += val;
buf.append(" %3.1lf", val);
}
buf.append_and_print_cr("");
double avg = total / (double) no_of_gc_threads();
buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
avg, min, max, max - min);
}
void G1CollectorPolicy::print_par_sizes(int level,
const char* str,
double* data) {
double min = data[0], max = data[0];
double total = 0.0;
LineBuffer buf(level);
buf.append("[%s :", str);
for (uint i = 0; i < no_of_gc_threads(); ++i) {
double val = data[i];
if (val < min)
min = val;
if (val > max)
max = val;
total += val;
buf.append(" %d", (int) val);
}
buf.append_and_print_cr("");
double avg = total / (double) no_of_gc_threads();
buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
(int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
}
void G1CollectorPolicy::print_stats(int level,
const char* str,
double value) {
LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
}
void G1CollectorPolicy::print_stats(int level,
const char* str,
int value) {
LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
}
double G1CollectorPolicy::avg_value(double* data) {
if (G1CollectedHeap::use_parallel_gc_threads()) {
double ret = 0.0;
for (uint i = 0; i < no_of_gc_threads(); ++i) {
ret += data[i];
}
return ret / (double) no_of_gc_threads();
} else {
return data[0];
}
}
double G1CollectorPolicy::max_value(double* data) {
if (G1CollectedHeap::use_parallel_gc_threads()) {
double ret = data[0];
for (uint i = 1; i < no_of_gc_threads(); ++i) {
if (data[i] > ret) {
ret = data[i];
}
}
return ret;
} else {
return data[0];
}
}
double G1CollectorPolicy::sum_of_values(double* data) {
if (G1CollectedHeap::use_parallel_gc_threads()) {
double sum = 0.0;
for (uint i = 0; i < no_of_gc_threads(); i++) {
sum += data[i];
}
return sum;
} else {
return data[0];
}
}
double G1CollectorPolicy::max_sum(double* data1, double* data2) {
double ret = data1[0] + data2[0];
if (G1CollectedHeap::use_parallel_gc_threads()) {
for (uint i = 1; i < no_of_gc_threads(); ++i) {
double data = data1[i] + data2[i];
if (data > ret) {
ret = data;
}
}
}
return ret;
}
// Anything below that is considered to be zero
#define MIN_TIMER_GRANULARITY 0.0000001
void G1CollectorPolicy::record_collection_pause_end(int no_of_gc_threads) {
double end_time_sec = os::elapsedTime();
double elapsed_ms = _last_pause_time_ms;
bool parallel = G1CollectedHeap::use_parallel_gc_threads();
assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
"otherwise, the subtraction below does not make sense");
size_t rs_size =
_cur_collection_pause_used_regions_at_start - cset_region_length();
size_t cur_used_bytes = _g1->used();
assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
bool last_pause_included_initial_mark = false;
bool update_stats = !_g1->evacuation_failed();
set_no_of_gc_threads(no_of_gc_threads);
#ifndef PRODUCT
if (G1YoungSurvRateVerbose) {
gclog_or_tty->print_cr("");
_short_lived_surv_rate_group->print();
// do that for any other surv rate groups too
}
#endif // PRODUCT
last_pause_included_initial_mark = during_initial_mark_pause();
if (last_pause_included_initial_mark)
record_concurrent_mark_init_end(0.0);
size_t marking_initiating_used_threshold =
(_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
if (!_g1->mark_in_progress() && !_last_full_young_gc) {
assert(!last_pause_included_initial_mark, "invariant");
if (cur_used_bytes > marking_initiating_used_threshold) {
if (cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
assert(!during_initial_mark_pause(), "we should not see this here");
ergo_verbose3(ErgoConcCycles,
"request concurrent cycle initiation",
ergo_format_reason("occupancy higher than threshold")
ergo_format_byte("occupancy")
ergo_format_byte_perc("threshold"),
cur_used_bytes,
marking_initiating_used_threshold,
(double) InitiatingHeapOccupancyPercent);
// Note: this might have already been set, if during the last
// pause we decided to start a cycle but at the beginning of
// this pause we decided to postpone it. That's OK.
set_initiate_conc_mark_if_possible();
} else {
ergo_verbose2(ErgoConcCycles,
"do not request concurrent cycle initiation",
ergo_format_reason("occupancy lower than previous occupancy")
ergo_format_byte("occupancy")
ergo_format_byte("previous occupancy"),
cur_used_bytes,
_prev_collection_pause_used_at_end_bytes);
}
}
}
_prev_collection_pause_used_at_end_bytes = cur_used_bytes;
_mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
end_time_sec, false);
// This assert is exempted when we're doing parallel collection pauses,
// because the fragmentation caused by the parallel GC allocation buffers
// can lead to more memory being used during collection than was used
// before. Best leave this out until the fragmentation problem is fixed.
// Pauses in which evacuation failed can also lead to negative
// collections, since no space is reclaimed from a region containing an
// object whose evacuation failed.
// Further, we're now always doing parallel collection. But I'm still
// leaving this here as a placeholder for a more precise assertion later.
// (DLD, 10/05.)
assert((true || parallel) // Always using GC LABs now.
|| _g1->evacuation_failed()
|| _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
"Negative collection");
size_t freed_bytes =
_cur_collection_pause_used_at_start_bytes - cur_used_bytes;
size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
double survival_fraction =
(double)surviving_bytes/
(double)_collection_set_bytes_used_before;
// These values are used to update the summary information that is
// displayed when TraceGen0Time is enabled, and are output as part
// of the PrintGCDetails output, in the non-parallel case.
double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
double update_rs_time = avg_value(_par_last_update_rs_times_ms);
double update_rs_processed_buffers =
sum_of_values(_par_last_update_rs_processed_buffers);
double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
double termination_time = avg_value(_par_last_termination_times_ms);
double known_time = ext_root_scan_time +
mark_stack_scan_time +
update_rs_time +
scan_rs_time +
obj_copy_time;
double other_time_ms = elapsed_ms;
// Subtract the SATB drain time. It's initialized to zero at the
// start of the pause and is updated during the pause if marking
// is in progress.
other_time_ms -= _cur_satb_drain_time_ms;
if (parallel) {
other_time_ms -= _cur_collection_par_time_ms;
} else {
other_time_ms -= known_time;
}
// Subtract the time taken to clean the card table from the
// current value of "other time"
other_time_ms -= _cur_clear_ct_time_ms;
// Subtract the time spent completing marking in the collection
// set. Note if marking is not in progress during the pause
// the value of _mark_closure_time_ms will be zero.
other_time_ms -= _mark_closure_time_ms;
// TraceGen0Time and TraceGen1Time summary info updating.
_all_pause_times_ms->add(elapsed_ms);
if (update_stats) {
_summary->record_total_time_ms(elapsed_ms);
_summary->record_other_time_ms(other_time_ms);
MainBodySummary* body_summary = _summary->main_body_summary();
assert(body_summary != NULL, "should not be null!");
// This will be non-zero iff marking is currently in progress (i.e.
// _g1->mark_in_progress() == true) and the currrent pause was not
// an initial mark pause. Since the body_summary items are NumberSeqs,
// however, they have to be consistent and updated in lock-step with
// each other. Therefore we unconditionally record the SATB drain
// time - even if it's zero.
body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
body_summary->record_update_rs_time_ms(update_rs_time);
body_summary->record_scan_rs_time_ms(scan_rs_time);
body_summary->record_obj_copy_time_ms(obj_copy_time);
if (parallel) {
body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
body_summary->record_termination_time_ms(termination_time);
double parallel_known_time = known_time + termination_time;
double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
body_summary->record_parallel_other_time_ms(parallel_other_time);
}
body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
// We exempt parallel collection from this check because Alloc Buffer
// fragmentation can produce negative collections. Same with evac
// failure.
// Further, we're now always doing parallel collection. But I'm still
// leaving this here as a placeholder for a more precise assertion later.
// (DLD, 10/05.
assert((true || parallel)
|| _g1->evacuation_failed()
|| surviving_bytes <= _collection_set_bytes_used_before,
"Or else negative collection!");
// this is where we update the allocation rate of the application
double app_time_ms =
(_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
if (app_time_ms < MIN_TIMER_GRANULARITY) {
// This usually happens due to the timer not having the required
// granularity. Some Linuxes are the usual culprits.
// We'll just set it to something (arbitrarily) small.
app_time_ms = 1.0;
}
// We maintain the invariant that all objects allocated by mutator
// threads will be allocated out of eden regions. So, we can use
// the eden region number allocated since the previous GC to
// calculate the application's allocate rate. The only exception
// to that is humongous objects that are allocated separately. But
// given that humongous object allocations do not really affect
// either the pause's duration nor when the next pause will take
// place we can safely ignore them here.
size_t regions_allocated = eden_cset_region_length();
double alloc_rate_ms = (double) regions_allocated / app_time_ms;
_alloc_rate_ms_seq->add(alloc_rate_ms);
double interval_ms =
(end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
update_recent_gc_times(end_time_sec, elapsed_ms);
_recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
if (recent_avg_pause_time_ratio() < 0.0 ||
(recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
#ifndef PRODUCT
// Dump info to allow post-facto debugging
gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
gclog_or_tty->print_cr("-------------------------------------------");
gclog_or_tty->print_cr("Recent GC Times (ms):");
_recent_gc_times_ms->dump();
gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
_recent_prev_end_times_for_all_gcs_sec->dump();
gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
_recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
// In debug mode, terminate the JVM if the user wants to debug at this point.
assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
#endif // !PRODUCT
// Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
// CR 6902692 by redoing the manner in which the ratio is incrementally computed.
if (_recent_avg_pause_time_ratio < 0.0) {
_recent_avg_pause_time_ratio = 0.0;
} else {
assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
_recent_avg_pause_time_ratio = 1.0;
}
}
}
for (int i = 0; i < _aux_num; ++i) {
if (_cur_aux_times_set[i]) {
_all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
}
}
// PrintGCDetails output
if (PrintGCDetails) {
bool print_marking_info =
_g1->mark_in_progress() && !last_pause_included_initial_mark;
gclog_or_tty->print_cr("%s, %1.8lf secs]",
(last_pause_included_initial_mark) ? " (initial-mark)" : "",
elapsed_ms / 1000.0);
if (print_marking_info) {
print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
}
if (parallel) {
print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);
print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
if (print_marking_info) {
print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
}
print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
print_par_stats(2, "Termination", _par_last_termination_times_ms);
print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);
for (int i = 0; i < _parallel_gc_threads; i++) {
_par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
double worker_known_time = _par_last_ext_root_scan_times_ms[i] +
_par_last_mark_stack_scan_times_ms[i] +
_par_last_update_rs_times_ms[i] +
_par_last_scan_rs_times_ms[i] +
_par_last_obj_copy_times_ms[i] +
_par_last_termination_times_ms[i];
_par_last_gc_worker_other_times_ms[i] = _cur_collection_par_time_ms - worker_known_time;
}
print_par_stats(2, "GC Worker", _par_last_gc_worker_times_ms);
print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);
} else {
print_stats(1, "Ext Root Scanning", ext_root_scan_time);
if (print_marking_info) {
print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
}
print_stats(1, "Update RS", update_rs_time);
print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);
print_stats(1, "Scan RS", scan_rs_time);
print_stats(1, "Object Copying", obj_copy_time);
}
if (print_marking_info) {
print_stats(1, "Complete CSet Marking", _mark_closure_time_ms);
}
print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
#ifndef PRODUCT
print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
if (_num_cc_clears > 0) {
print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
}
#endif
print_stats(1, "Other", other_time_ms);
print_stats(2, "Choose CSet",
(_recorded_young_cset_choice_time_ms +
_recorded_non_young_cset_choice_time_ms));
print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
print_stats(2, "Free CSet",
(_recorded_young_free_cset_time_ms +
_recorded_non_young_free_cset_time_ms));
for (int i = 0; i < _aux_num; ++i) {
if (_cur_aux_times_set[i]) {
char buffer[96];
sprintf(buffer, "Aux%d", i);
print_stats(1, buffer, _cur_aux_times_ms[i]);
}
}
}
// Update the efficiency-since-mark vars.
double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
if (elapsed_ms < MIN_TIMER_GRANULARITY) {
// This usually happens due to the timer not having the required
// granularity. Some Linuxes are the usual culprits.
// We'll just set it to something (arbitrarily) small.
proc_ms = 1.0;
}
double cur_efficiency = (double) freed_bytes / proc_ms;
bool new_in_marking_window = _in_marking_window;
bool new_in_marking_window_im = false;
if (during_initial_mark_pause()) {
new_in_marking_window = true;
new_in_marking_window_im = true;
}
if (_last_full_young_gc) {
if (!last_pause_included_initial_mark) {
ergo_verbose2(ErgoPartiallyYoungGCs,
"start partially-young GCs",
ergo_format_byte_perc("known garbage"),
_known_garbage_bytes, _known_garbage_ratio * 100.0);
set_full_young_gcs(false);
} else {
ergo_verbose0(ErgoPartiallyYoungGCs,
"do not start partially-young GCs",
ergo_format_reason("concurrent cycle is about to start"));
}
_last_full_young_gc = false;
}
if ( !_last_young_gc_full ) {
if (_should_revert_to_full_young_gcs) {
ergo_verbose2(ErgoPartiallyYoungGCs,
"end partially-young GCs",
ergo_format_reason("partially-young GCs end requested")
ergo_format_byte_perc("known garbage"),
_known_garbage_bytes, _known_garbage_ratio * 100.0);
set_full_young_gcs(true);
} else if (_known_garbage_ratio < 0.05) {
ergo_verbose3(ErgoPartiallyYoungGCs,
"end partially-young GCs",
ergo_format_reason("known garbage percent lower than threshold")
ergo_format_byte_perc("known garbage")
ergo_format_perc("threshold"),
_known_garbage_bytes, _known_garbage_ratio * 100.0,
0.05 * 100.0);
set_full_young_gcs(true);
} else if (adaptive_young_list_length() &&
(get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) {
ergo_verbose5(ErgoPartiallyYoungGCs,
"end partially-young GCs",
ergo_format_reason("current GC efficiency lower than "
"predicted fully-young GC efficiency")
ergo_format_double("GC efficiency factor")
ergo_format_double("current GC efficiency")
ergo_format_double("predicted fully-young GC efficiency")
ergo_format_byte_perc("known garbage"),
get_gc_eff_factor(), cur_efficiency,
predict_young_gc_eff(),
_known_garbage_bytes, _known_garbage_ratio * 100.0);
set_full_young_gcs(true);
}
}
_should_revert_to_full_young_gcs = false;
if (_last_young_gc_full && !_during_marking) {
_young_gc_eff_seq->add(cur_efficiency);
}
_short_lived_surv_rate_group->start_adding_regions();
// do that for any other surv rate groupsx
if (update_stats) {
double pause_time_ms = elapsed_ms;
size_t diff = 0;
if (_max_pending_cards >= _pending_cards)
diff = _max_pending_cards - _pending_cards;
_pending_card_diff_seq->add((double) diff);
double cost_per_card_ms = 0.0;
if (_pending_cards > 0) {
cost_per_card_ms = update_rs_time / (double) _pending_cards;
_cost_per_card_ms_seq->add(cost_per_card_ms);
}
size_t cards_scanned = _g1->cards_scanned();
double cost_per_entry_ms = 0.0;
if (cards_scanned > 10) {
cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
if (_last_young_gc_full)
_cost_per_entry_ms_seq->add(cost_per_entry_ms);
else
_partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
}
if (_max_rs_lengths > 0) {
double cards_per_entry_ratio =
(double) cards_scanned / (double) _max_rs_lengths;
if (_last_young_gc_full)
_fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
else
_partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
}
// It turns out that, sometimes, _max_rs_lengths can get smaller
// than _recorded_rs_lengths which causes rs_length_diff to get
// very large and mess up the RSet length predictions. We'll be
// defensive until we work out why this happens.
size_t rs_length_diff = 0;
if (_max_rs_lengths > _recorded_rs_lengths) {
rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
}
_rs_length_diff_seq->add((double) rs_length_diff);
size_t copied_bytes = surviving_bytes;
double cost_per_byte_ms = 0.0;
if (copied_bytes > 0) {
cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
if (_in_marking_window)
_cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
else
_cost_per_byte_ms_seq->add(cost_per_byte_ms);
}
double all_other_time_ms = pause_time_ms -
(update_rs_time + scan_rs_time + obj_copy_time +
_mark_closure_time_ms + termination_time);
double young_other_time_ms = 0.0;
if (young_cset_region_length() > 0) {
young_other_time_ms =
_recorded_young_cset_choice_time_ms +
_recorded_young_free_cset_time_ms;
_young_other_cost_per_region_ms_seq->add(young_other_time_ms /
(double) young_cset_region_length());
}
double non_young_other_time_ms = 0.0;
if (old_cset_region_length() > 0) {
non_young_other_time_ms =
_recorded_non_young_cset_choice_time_ms +
_recorded_non_young_free_cset_time_ms;
_non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
(double) old_cset_region_length());
}
double constant_other_time_ms = all_other_time_ms -
(young_other_time_ms + non_young_other_time_ms);
_constant_other_time_ms_seq->add(constant_other_time_ms);
double survival_ratio = 0.0;
if (_bytes_in_collection_set_before_gc > 0) {
survival_ratio = (double) _bytes_copied_during_gc /
(double) _bytes_in_collection_set_before_gc;
}
_pending_cards_seq->add((double) _pending_cards);
_rs_lengths_seq->add((double) _max_rs_lengths);
double expensive_region_limit_ms =
(double) MaxGCPauseMillis - predict_constant_other_time_ms();
if (expensive_region_limit_ms < 0.0) {
// this means that the other time was predicted to be longer than
// than the max pause time
expensive_region_limit_ms = (double) MaxGCPauseMillis;
}
_expensive_region_limit_ms = expensive_region_limit_ms;
}
_in_marking_window = new_in_marking_window;
_in_marking_window_im = new_in_marking_window_im;
_free_regions_at_end_of_collection = _g1->free_regions();
update_young_list_target_length();
// Note that _mmu_tracker->max_gc_time() returns the time in seconds.
double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
}
#define EXT_SIZE_FORMAT "%d%s"
#define EXT_SIZE_PARAMS(bytes) \
byte_size_in_proper_unit((bytes)), \
proper_unit_for_byte_size((bytes))
void G1CollectorPolicy::print_heap_transition() {
if (PrintGCDetails) {
YoungList* young_list = _g1->young_list();
size_t eden_bytes = young_list->eden_used_bytes();
size_t survivor_bytes = young_list->survivor_used_bytes();
size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
size_t used = _g1->used();
size_t capacity = _g1->capacity();
size_t eden_capacity =
(_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
gclog_or_tty->print_cr(
" [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
"Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
"Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
EXT_SIZE_PARAMS(_eden_bytes_before_gc),
EXT_SIZE_PARAMS(_prev_eden_capacity),
EXT_SIZE_PARAMS(eden_bytes),
EXT_SIZE_PARAMS(eden_capacity),
EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
EXT_SIZE_PARAMS(survivor_bytes),
EXT_SIZE_PARAMS(used_before_gc),
EXT_SIZE_PARAMS(_capacity_before_gc),
EXT_SIZE_PARAMS(used),
EXT_SIZE_PARAMS(capacity));
_prev_eden_capacity = eden_capacity;
} else if (PrintGC) {
_g1->print_size_transition(gclog_or_tty,
_cur_collection_pause_used_at_start_bytes,
_g1->used(), _g1->capacity());
}
}
void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
double update_rs_processed_buffers,
double goal_ms) {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
if (G1UseAdaptiveConcRefinement) {
const int k_gy = 3, k_gr = 6;
const double inc_k = 1.1, dec_k = 0.9;
int g = cg1r->green_zone();
if (update_rs_time > goal_ms) {
g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
} else {
if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
g = (int)MAX2(g * inc_k, g + 1.0);
}
}
// Change the refinement threads params
cg1r->set_green_zone(g);
cg1r->set_yellow_zone(g * k_gy);
cg1r->set_red_zone(g * k_gr);
cg1r->reinitialize_threads();
int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
cg1r->yellow_zone());
// Change the barrier params
dcqs.set_process_completed_threshold(processing_threshold);
dcqs.set_max_completed_queue(cg1r->red_zone());
}
int curr_queue_size = dcqs.completed_buffers_num();
if (curr_queue_size >= cg1r->yellow_zone()) {
dcqs.set_completed_queue_padding(curr_queue_size);
} else {
dcqs.set_completed_queue_padding(0);
}
dcqs.notify_if_necessary();
}
double
G1CollectorPolicy::
predict_young_collection_elapsed_time_ms(size_t adjustment) {
guarantee( adjustment == 0 || adjustment == 1, "invariant" );
G1CollectedHeap* g1h = G1CollectedHeap::heap();
size_t young_num = g1h->young_list()->length();
if (young_num == 0)
return 0.0;
young_num += adjustment;
size_t pending_cards = predict_pending_cards();
size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
predict_rs_length_diff();
size_t card_num;
if (full_young_gcs())
card_num = predict_young_card_num(rs_lengths);
else
card_num = predict_non_young_card_num(rs_lengths);
size_t young_byte_size = young_num * HeapRegion::GrainBytes;
double accum_yg_surv_rate =
_short_lived_surv_rate_group->accum_surv_rate(adjustment);
size_t bytes_to_copy =
(size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
return
predict_rs_update_time_ms(pending_cards) +
predict_rs_scan_time_ms(card_num) +
predict_object_copy_time_ms(bytes_to_copy) +
predict_young_other_time_ms(young_num) +
predict_constant_other_time_ms();
}
double
G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
size_t rs_length = predict_rs_length_diff();
size_t card_num;
if (full_young_gcs())
card_num = predict_young_card_num(rs_length);
else
card_num = predict_non_young_card_num(rs_length);
return predict_base_elapsed_time_ms(pending_cards, card_num);
}
double
G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
size_t scanned_cards) {
return
predict_rs_update_time_ms(pending_cards) +
predict_rs_scan_time_ms(scanned_cards) +
predict_constant_other_time_ms();
}
double
G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
bool young) {
size_t rs_length = hr->rem_set()->occupied();
size_t card_num;
if (full_young_gcs())
card_num = predict_young_card_num(rs_length);
else
card_num = predict_non_young_card_num(rs_length);
size_t bytes_to_copy = predict_bytes_to_copy(hr);
double region_elapsed_time_ms =
predict_rs_scan_time_ms(card_num) +
predict_object_copy_time_ms(bytes_to_copy);
if (young)
region_elapsed_time_ms += predict_young_other_time_ms(1);
else
region_elapsed_time_ms += predict_non_young_other_time_ms(1);
return region_elapsed_time_ms;
}
size_t
G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
size_t bytes_to_copy;
if (hr->is_marked())
bytes_to_copy = hr->max_live_bytes();
else {
guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
"invariant" );
int age = hr->age_in_surv_rate_group();
double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
}
return bytes_to_copy;
}
void
G1CollectorPolicy::init_cset_region_lengths(size_t eden_cset_region_length,
size_t survivor_cset_region_length) {
_eden_cset_region_length = eden_cset_region_length;
_survivor_cset_region_length = survivor_cset_region_length;
_old_cset_region_length = 0;
}
void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
_recorded_rs_lengths = rs_lengths;
}
void G1CollectorPolicy::check_if_region_is_too_expensive(double
predicted_time_ms) {
// I don't think we need to do this when in young GC mode since
// marking will be initiated next time we hit the soft limit anyway...
if (predicted_time_ms > _expensive_region_limit_ms) {
ergo_verbose2(ErgoPartiallyYoungGCs,
"request partially-young GCs end",
ergo_format_reason("predicted region time higher than threshold")
ergo_format_ms("predicted region time")
ergo_format_ms("threshold"),
predicted_time_ms, _expensive_region_limit_ms);
// no point in doing another partial one
_should_revert_to_full_young_gcs = true;
}
}
void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
double elapsed_ms) {
_recent_gc_times_ms->add(elapsed_ms);
_recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
_prev_collection_pause_end_ms = end_time_sec * 1000.0;
}
size_t G1CollectorPolicy::expansion_amount() {
double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
double threshold = _gc_overhead_perc;
if (recent_gc_overhead > threshold) {
// We will double the existing space, or take
// G1ExpandByPercentOfAvailable % of the available expansion
// space, whichever is smaller, bounded below by a minimum
// expansion (unless that's all that's left.)
const size_t min_expand_bytes = 1*M;
size_t reserved_bytes = _g1->max_capacity();
size_t committed_bytes = _g1->capacity();
size_t uncommitted_bytes = reserved_bytes - committed_bytes;
size_t expand_bytes;
size_t expand_bytes_via_pct =
uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
expand_bytes = MAX2(expand_bytes, min_expand_bytes);
expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
ergo_verbose5(ErgoHeapSizing,
"attempt heap expansion",
ergo_format_reason("recent GC overhead higher than "
"threshold after GC")
ergo_format_perc("recent GC overhead")
ergo_format_perc("threshold")
ergo_format_byte("uncommitted")
ergo_format_byte_perc("calculated expansion amount"),
recent_gc_overhead, threshold,
uncommitted_bytes,
expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
return expand_bytes;
} else {
return 0;
}
}
class CountCSClosure: public HeapRegionClosure {
G1CollectorPolicy* _g1_policy;
public:
CountCSClosure(G1CollectorPolicy* g1_policy) :
_g1_policy(g1_policy) {}
bool doHeapRegion(HeapRegion* r) {
_g1_policy->_bytes_in_collection_set_before_gc += r->used();
return false;
}
};
void G1CollectorPolicy::count_CS_bytes_used() {
CountCSClosure cs_closure(this);
_g1->collection_set_iterate(&cs_closure);
}
void G1CollectorPolicy::print_summary(int level,
const char* str,
NumberSeq* seq) const {
double sum = seq->sum();
LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
str, sum / 1000.0, seq->avg());
}
void G1CollectorPolicy::print_summary_sd(int level,
const char* str,
NumberSeq* seq) const {
print_summary(level, str, seq);
LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
seq->num(), seq->sd(), seq->maximum());
}
void G1CollectorPolicy::check_other_times(int level,
NumberSeq* other_times_ms,
NumberSeq* calc_other_times_ms) const {
bool should_print = false;
LineBuffer buf(level + 2);
double max_sum = MAX2(fabs(other_times_ms->sum()),
fabs(calc_other_times_ms->sum()));
double min_sum = MIN2(fabs(other_times_ms->sum()),
fabs(calc_other_times_ms->sum()));
double sum_ratio = max_sum / min_sum;
if (sum_ratio > 1.1) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
}
double max_avg = MAX2(fabs(other_times_ms->avg()),
fabs(calc_other_times_ms->avg()));
double min_avg = MIN2(fabs(other_times_ms->avg()),
fabs(calc_other_times_ms->avg()));
double avg_ratio = max_avg / min_avg;
if (avg_ratio > 1.1) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
}
if (other_times_ms->sum() < -0.01) {
buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
}
if (other_times_ms->avg() < -0.01) {
buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
}
if (calc_other_times_ms->sum() < -0.01) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
}
if (calc_other_times_ms->avg() < -0.01) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
}
if (should_print)
print_summary(level, "Other(Calc)", calc_other_times_ms);
}
void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
bool parallel = G1CollectedHeap::use_parallel_gc_threads();
MainBodySummary* body_summary = summary->main_body_summary();
if (summary->get_total_seq()->num() > 0) {
print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
if (body_summary != NULL) {
print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
if (parallel) {
print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
print_summary(2, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
print_summary(2, "Mark Stack Scanning", body_summary->get_mark_stack_scan_seq());
print_summary(2, "Update RS", body_summary->get_update_rs_seq());
print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
print_summary(2, "Termination", body_summary->get_termination_seq());
print_summary(2, "Parallel Other", body_summary->get_parallel_other_seq());
{
NumberSeq* other_parts[] = {
body_summary->get_ext_root_scan_seq(),
body_summary->get_mark_stack_scan_seq(),
body_summary->get_update_rs_seq(),
body_summary->get_scan_rs_seq(),
body_summary->get_obj_copy_seq(),
body_summary->get_termination_seq()
};
NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
6, other_parts);
check_other_times(2, body_summary->get_parallel_other_seq(),
&calc_other_times_ms);
}
} else {
print_summary(1, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
print_summary(1, "Mark Stack Scanning", body_summary->get_mark_stack_scan_seq());
print_summary(1, "Update RS", body_summary->get_update_rs_seq());
print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
}
}
print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
print_summary(1, "Other", summary->get_other_seq());
{
if (body_summary != NULL) {
NumberSeq calc_other_times_ms;
if (parallel) {
// parallel
NumberSeq* other_parts[] = {
body_summary->get_satb_drain_seq(),
body_summary->get_parallel_seq(),
body_summary->get_clear_ct_seq()
};
calc_other_times_ms = NumberSeq(summary->get_total_seq(),
3, other_parts);
} else {
// serial
NumberSeq* other_parts[] = {
body_summary->get_satb_drain_seq(),
body_summary->get_update_rs_seq(),
body_summary->get_ext_root_scan_seq(),
body_summary->get_mark_stack_scan_seq(),
body_summary->get_scan_rs_seq(),
body_summary->get_obj_copy_seq()
};
calc_other_times_ms = NumberSeq(summary->get_total_seq(),
6, other_parts);
}
check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
}
}
} else {
LineBuffer(1).append_and_print_cr("none");
}
LineBuffer(0).append_and_print_cr("");
}
void G1CollectorPolicy::print_tracing_info() const {
if (TraceGen0Time) {
gclog_or_tty->print_cr("ALL PAUSES");
print_summary_sd(0, "Total", _all_pause_times_ms);
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr("EVACUATION PAUSES");
print_summary(_summary);
gclog_or_tty->print_cr("MISC");
print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
print_summary_sd(0, "Yields", _all_yield_times_ms);
for (int i = 0; i < _aux_num; ++i) {
if (_all_aux_times_ms[i].num() > 0) {
char buffer[96];
sprintf(buffer, "Aux%d", i);
print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
}
}
}
if (TraceGen1Time) {
if (_all_full_gc_times_ms->num() > 0) {
gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
_all_full_gc_times_ms->num(),
_all_full_gc_times_ms->sum() / 1000.0);
gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
_all_full_gc_times_ms->sd(),
_all_full_gc_times_ms->maximum());
}
}
}
void G1CollectorPolicy::print_yg_surv_rate_info() const {
#ifndef PRODUCT
_short_lived_surv_rate_group->print_surv_rate_summary();
// add this call for any other surv rate groups
#endif // PRODUCT
}
#ifndef PRODUCT
// for debugging, bit of a hack...
static char*
region_num_to_mbs(int length) {
static char buffer[64];
double bytes = (double) (length * HeapRegion::GrainBytes);
double mbs = bytes / (double) (1024 * 1024);
sprintf(buffer, "%7.2lfMB", mbs);
return buffer;
}
#endif // PRODUCT
size_t G1CollectorPolicy::max_regions(int purpose) {
switch (purpose) {
case GCAllocForSurvived:
return _max_survivor_regions;
case GCAllocForTenured:
return REGIONS_UNLIMITED;
default:
ShouldNotReachHere();
return REGIONS_UNLIMITED;
};
}
void G1CollectorPolicy::update_max_gc_locker_expansion() {
size_t expansion_region_num = 0;
if (GCLockerEdenExpansionPercent > 0) {
double perc = (double) GCLockerEdenExpansionPercent / 100.0;
double expansion_region_num_d = perc * (double) _young_list_target_length;
// We use ceiling so that if expansion_region_num_d is > 0.0 (but
// less than 1.0) we'll get 1.
expansion_region_num = (size_t) ceil(expansion_region_num_d);
} else {
assert(expansion_region_num == 0, "sanity");
}
_young_list_max_length = _young_list_target_length + expansion_region_num;
assert(_young_list_target_length <= _young_list_max_length, "post-condition");
}
// Calculates survivor space parameters.
void G1CollectorPolicy::update_survivors_policy() {
double max_survivor_regions_d =
(double) _young_list_target_length / (double) SurvivorRatio;
// We use ceiling so that if max_survivor_regions_d is > 0.0 (but
// smaller than 1.0) we'll get 1.
_max_survivor_regions = (size_t) ceil(max_survivor_regions_d);
_tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
HeapRegion::GrainWords * _max_survivor_regions);
}
#ifndef PRODUCT
class HRSortIndexIsOKClosure: public HeapRegionClosure {
CollectionSetChooser* _chooser;
public:
HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
_chooser(chooser) {}
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
}
return false;
}
};
bool G1CollectorPolicy::assertMarkedBytesDataOK() {
HRSortIndexIsOKClosure cl(_collectionSetChooser);
_g1->heap_region_iterate(&cl);
return true;
}
#endif
bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
GCCause::Cause gc_cause) {
bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
if (!during_cycle) {
ergo_verbose1(ErgoConcCycles,
"request concurrent cycle initiation",
ergo_format_reason("requested by GC cause")
ergo_format_str("GC cause"),
GCCause::to_string(gc_cause));
set_initiate_conc_mark_if_possible();
return true;
} else {
ergo_verbose1(ErgoConcCycles,
"do not request concurrent cycle initiation",
ergo_format_reason("concurrent cycle already in progress")
ergo_format_str("GC cause"),
GCCause::to_string(gc_cause));
return false;
}
}
void
G1CollectorPolicy::decide_on_conc_mark_initiation() {
// We are about to decide on whether this pause will be an
// initial-mark pause.
// First, during_initial_mark_pause() should not be already set. We
// will set it here if we have to. However, it should be cleared by
// the end of the pause (it's only set for the duration of an
// initial-mark pause).
assert(!during_initial_mark_pause(), "pre-condition");
if (initiate_conc_mark_if_possible()) {
// We had noticed on a previous pause that the heap occupancy has
// gone over the initiating threshold and we should start a
// concurrent marking cycle. So we might initiate one.
bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
if (!during_cycle) {
// The concurrent marking thread is not "during a cycle", i.e.,
// it has completed the last one. So we can go ahead and
// initiate a new cycle.
set_during_initial_mark_pause();
// We do not allow non-full young GCs during marking.
if (!full_young_gcs()) {
set_full_young_gcs(true);
ergo_verbose0(ErgoPartiallyYoungGCs,
"end partially-young GCs",
ergo_format_reason("concurrent cycle is about to start"));
}
// And we can now clear initiate_conc_mark_if_possible() as
// we've already acted on it.
clear_initiate_conc_mark_if_possible();
ergo_verbose0(ErgoConcCycles,
"initiate concurrent cycle",
ergo_format_reason("concurrent cycle initiation requested"));
} else {
// The concurrent marking thread is still finishing up the
// previous cycle. If we start one right now the two cycles
// overlap. In particular, the concurrent marking thread might
// be in the process of clearing the next marking bitmap (which
// we will use for the next cycle if we start one). Starting a
// cycle now will be bad given that parts of the marking
// information might get cleared by the marking thread. And we
// cannot wait for the marking thread to finish the cycle as it
// periodically yields while clearing the next marking bitmap
// and, if it's in a yield point, it's waiting for us to
// finish. So, at this point we will not start a cycle and we'll
// let the concurrent marking thread complete the last one.
ergo_verbose0(ErgoConcCycles,
"do not initiate concurrent cycle",
ergo_format_reason("concurrent cycle already in progress"));
}
}
}
class KnownGarbageClosure: public HeapRegionClosure {
CollectionSetChooser* _hrSorted;
public:
KnownGarbageClosure(CollectionSetChooser* hrSorted) :
_hrSorted(hrSorted)
{}
bool doHeapRegion(HeapRegion* r) {
// We only include humongous regions in collection
// sets when concurrent mark shows that their contained object is
// unreachable.
// Do we have any marking information for this region?
if (r->is_marked()) {
// We don't include humongous regions in collection
// sets because we collect them immediately at the end of a marking
// cycle. We also don't include young regions because we *must*
// include them in the next collection pause.
if (!r->isHumongous() && !r->is_young()) {
_hrSorted->addMarkedHeapRegion(r);
}
}
return false;
}
};
class ParKnownGarbageHRClosure: public HeapRegionClosure {
CollectionSetChooser* _hrSorted;
jint _marked_regions_added;
jint _chunk_size;
jint _cur_chunk_idx;
jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
int _worker;
int _invokes;
void get_new_chunk() {
_cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
_cur_chunk_end = _cur_chunk_idx + _chunk_size;
}
void add_region(HeapRegion* r) {
if (_cur_chunk_idx == _cur_chunk_end) {
get_new_chunk();
}
assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
_hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
_marked_regions_added++;
_cur_chunk_idx++;
}
public:
ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
jint chunk_size,
int worker) :
_hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
_marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
_invokes(0)
{}
bool doHeapRegion(HeapRegion* r) {
// We only include humongous regions in collection
// sets when concurrent mark shows that their contained object is
// unreachable.
_invokes++;
// Do we have any marking information for this region?
if (r->is_marked()) {
// We don't include humongous regions in collection
// sets because we collect them immediately at the end of a marking
// cycle.
// We also do not include young regions in collection sets
if (!r->isHumongous() && !r->is_young()) {
add_region(r);
}
}
return false;
}
jint marked_regions_added() { return _marked_regions_added; }
int invokes() { return _invokes; }
};
class ParKnownGarbageTask: public AbstractGangTask {
CollectionSetChooser* _hrSorted;
jint _chunk_size;
G1CollectedHeap* _g1;
public:
ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
AbstractGangTask("ParKnownGarbageTask"),
_hrSorted(hrSorted), _chunk_size(chunk_size),
_g1(G1CollectedHeap::heap())
{}
void work(int i) {
ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
// Back to zero for the claim value.
_g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
_g1->workers()->active_workers(),
HeapRegion::InitialClaimValue);
jint regions_added = parKnownGarbageCl.marked_regions_added();
_hrSorted->incNumMarkedHeapRegions(regions_added);
if (G1PrintParCleanupStats) {
gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
i, parKnownGarbageCl.invokes(), regions_added);
}
}
};
void
G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
double start_sec;
if (G1PrintParCleanupStats) {
start_sec = os::elapsedTime();
}
_collectionSetChooser->clearMarkedHeapRegions();
double clear_marked_end_sec;
if (G1PrintParCleanupStats) {
clear_marked_end_sec = os::elapsedTime();
gclog_or_tty->print_cr(" clear marked regions: %8.3f ms.",
(clear_marked_end_sec - start_sec) * 1000.0);
}
if (G1CollectedHeap::use_parallel_gc_threads()) {
const size_t OverpartitionFactor = 4;
size_t WorkUnit;
// The use of MinChunkSize = 8 in the original code
// causes some assertion failures when the total number of
// region is less than 8. The code here tries to fix that.
// Should the original code also be fixed?
if (no_of_gc_threads > 0) {
const size_t MinWorkUnit =
MAX2(_g1->n_regions() / no_of_gc_threads, (size_t) 1U);
WorkUnit =
MAX2(_g1->n_regions() / (no_of_gc_threads * OverpartitionFactor),
MinWorkUnit);
} else {
assert(no_of_gc_threads > 0,
"The active gc workers should be greater than 0");
// In a product build do something reasonable to avoid a crash.
const size_t MinWorkUnit =
MAX2(_g1->n_regions() / ParallelGCThreads, (size_t) 1U);
WorkUnit =
MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
MinWorkUnit);
}
_collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
WorkUnit);
ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
(int) WorkUnit);
_g1->workers()->run_task(&parKnownGarbageTask);
assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
"sanity check");
} else {
KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
_g1->heap_region_iterate(&knownGarbagecl);
}
double known_garbage_end_sec;
if (G1PrintParCleanupStats) {
known_garbage_end_sec = os::elapsedTime();
gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
(known_garbage_end_sec - clear_marked_end_sec) * 1000.0);
}
_collectionSetChooser->sortMarkedHeapRegions();
double end_sec = os::elapsedTime();
if (G1PrintParCleanupStats) {
gclog_or_tty->print_cr(" sorting: %8.3f ms.",
(end_sec - known_garbage_end_sec) * 1000.0);
}
double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
_concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
_cur_mark_stop_world_time_ms += elapsed_time_ms;
_prev_collection_pause_end_ms += elapsed_time_ms;
_mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
}
// Add the heap region at the head of the non-incremental collection set
void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
assert(_inc_cset_build_state == Active, "Precondition");
assert(!hr->is_young(), "non-incremental add of young region");
if (_g1->mark_in_progress())
_g1->concurrent_mark()->registerCSetRegion(hr);
assert(!hr->in_collection_set(), "should not already be in the CSet");
hr->set_in_collection_set(true);
hr->set_next_in_collection_set(_collection_set);
_collection_set = hr;
_collection_set_bytes_used_before += hr->used();
_g1->register_region_with_in_cset_fast_test(hr);
size_t rs_length = hr->rem_set()->occupied();
_recorded_rs_lengths += rs_length;
_old_cset_region_length += 1;
}
// Initialize the per-collection-set information
void G1CollectorPolicy::start_incremental_cset_building() {
assert(_inc_cset_build_state == Inactive, "Precondition");
_inc_cset_head = NULL;
_inc_cset_tail = NULL;
_inc_cset_bytes_used_before = 0;
_inc_cset_max_finger = 0;
_inc_cset_recorded_rs_lengths = 0;
_inc_cset_predicted_elapsed_time_ms = 0;
_inc_cset_build_state = Active;
}
void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
// This routine is used when:
// * adding survivor regions to the incremental cset at the end of an
// evacuation pause,
// * adding the current allocation region to the incremental cset
// when it is retired, and
// * updating existing policy information for a region in the
// incremental cset via young list RSet sampling.
// Therefore this routine may be called at a safepoint by the
// VM thread, or in-between safepoints by mutator threads (when
// retiring the current allocation region) or a concurrent
// refine thread (RSet sampling).
double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
size_t used_bytes = hr->used();
_inc_cset_recorded_rs_lengths += rs_length;
_inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
_inc_cset_bytes_used_before += used_bytes;
// Cache the values we have added to the aggregated informtion
// in the heap region in case we have to remove this region from
// the incremental collection set, or it is updated by the
// rset sampling code
hr->set_recorded_rs_length(rs_length);
hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
}
void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
// This routine is currently only called as part of the updating of
// existing policy information for regions in the incremental cset that
// is performed by the concurrent refine thread(s) as part of young list
// RSet sampling. Therefore we should not be at a safepoint.
assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
assert(hr->is_young(), "it should be");
size_t used_bytes = hr->used();
size_t old_rs_length = hr->recorded_rs_length();
double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
// Subtract the old recorded/predicted policy information for
// the given heap region from the collection set info.
_inc_cset_recorded_rs_lengths -= old_rs_length;
_inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
_inc_cset_bytes_used_before -= used_bytes;
// Clear the values cached in the heap region
hr->set_recorded_rs_length(0);
hr->set_predicted_elapsed_time_ms(0);
}
void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
// Update the collection set information that is dependent on the new RS length
assert(hr->is_young(), "Precondition");
remove_from_incremental_cset_info(hr);
add_to_incremental_cset_info(hr, new_rs_length);
}
void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
assert(hr->is_young(), "invariant");
assert(hr->young_index_in_cset() > -1, "should have already been set");
assert(_inc_cset_build_state == Active, "Precondition");
// We need to clear and set the cached recorded/cached collection set
// information in the heap region here (before the region gets added
// to the collection set). An individual heap region's cached values
// are calculated, aggregated with the policy collection set info,
// and cached in the heap region here (initially) and (subsequently)
// by the Young List sampling code.
size_t rs_length = hr->rem_set()->occupied();
add_to_incremental_cset_info(hr, rs_length);
HeapWord* hr_end = hr->end();
_inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
assert(!hr->in_collection_set(), "invariant");
hr->set_in_collection_set(true);
assert( hr->next_in_collection_set() == NULL, "invariant");
_g1->register_region_with_in_cset_fast_test(hr);
}
// Add the region at the RHS of the incremental cset
void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
// We should only ever be appending survivors at the end of a pause
assert( hr->is_survivor(), "Logic");
// Do the 'common' stuff
add_region_to_incremental_cset_common(hr);
// Now add the region at the right hand side
if (_inc_cset_tail == NULL) {
assert(_inc_cset_head == NULL, "invariant");
_inc_cset_head = hr;
} else {
_inc_cset_tail->set_next_in_collection_set(hr);
}
_inc_cset_tail = hr;
}
// Add the region to the LHS of the incremental cset
void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
// Survivors should be added to the RHS at the end of a pause
assert(!hr->is_survivor(), "Logic");
// Do the 'common' stuff
add_region_to_incremental_cset_common(hr);
// Add the region at the left hand side
hr->set_next_in_collection_set(_inc_cset_head);
if (_inc_cset_head == NULL) {
assert(_inc_cset_tail == NULL, "Invariant");
_inc_cset_tail = hr;
}
_inc_cset_head = hr;
}
#ifndef PRODUCT
void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
st->print_cr("\nCollection_set:");
HeapRegion* csr = list_head;
while (csr != NULL) {
HeapRegion* next = csr->next_in_collection_set();
assert(csr->in_collection_set(), "bad CS");
st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
"age: %4d, y: %d, surv: %d",
csr->bottom(), csr->end(),
csr->top(),
csr->prev_top_at_mark_start(),
csr->next_top_at_mark_start(),
csr->top_at_conc_mark_count(),
csr->age_in_surv_rate_group_cond(),
csr->is_young(),
csr->is_survivor());
csr = next;
}
}
#endif // !PRODUCT
void G1CollectorPolicy::choose_collection_set(double target_pause_time_ms) {
// Set this here - in case we're not doing young collections.
double non_young_start_time_sec = os::elapsedTime();
YoungList* young_list = _g1->young_list();
guarantee(target_pause_time_ms > 0.0,
err_msg("target_pause_time_ms = %1.6lf should be positive",
target_pause_time_ms));
guarantee(_collection_set == NULL, "Precondition");
double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
double predicted_pause_time_ms = base_time_ms;
double time_remaining_ms = target_pause_time_ms - base_time_ms;
ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
"start choosing CSet",
ergo_format_ms("predicted base time")
ergo_format_ms("remaining time")
ergo_format_ms("target pause time"),
base_time_ms, time_remaining_ms, target_pause_time_ms);
// the 10% and 50% values are arbitrary...
double threshold = 0.10 * target_pause_time_ms;
if (time_remaining_ms < threshold) {
double prev_time_remaining_ms = time_remaining_ms;
time_remaining_ms = 0.50 * target_pause_time_ms;
ergo_verbose3(ErgoCSetConstruction,
"adjust remaining time",
ergo_format_reason("remaining time lower than threshold")
ergo_format_ms("remaining time")
ergo_format_ms("threshold")
ergo_format_ms("adjusted remaining time"),
prev_time_remaining_ms, threshold, time_remaining_ms);
}
size_t expansion_bytes = _g1->expansion_regions() * HeapRegion::GrainBytes;
HeapRegion* hr;
double young_start_time_sec = os::elapsedTime();
_collection_set_bytes_used_before = 0;
_last_young_gc_full = full_young_gcs() ? true : false;
if (_last_young_gc_full) {
++_full_young_pause_num;
} else {
++_partial_young_pause_num;
}
// The young list is laid with the survivor regions from the previous
// pause are appended to the RHS of the young list, i.e.
// [Newly Young Regions ++ Survivors from last pause].
size_t survivor_region_length = young_list->survivor_length();
size_t eden_region_length = young_list->length() - survivor_region_length;
init_cset_region_lengths(eden_region_length, survivor_region_length);
hr = young_list->first_survivor_region();
while (hr != NULL) {
assert(hr->is_survivor(), "badly formed young list");
hr->set_young();
hr = hr->get_next_young_region();
}
// Clear the fields that point to the survivor list - they are all young now.
young_list->clear_survivors();
if (_g1->mark_in_progress())
_g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
_collection_set = _inc_cset_head;
_collection_set_bytes_used_before = _inc_cset_bytes_used_before;
time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
"add young regions to CSet",
ergo_format_region("eden")
ergo_format_region("survivors")
ergo_format_ms("predicted young region time"),
eden_region_length, survivor_region_length,
_inc_cset_predicted_elapsed_time_ms);
// The number of recorded young regions is the incremental
// collection set's current size
set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
double young_end_time_sec = os::elapsedTime();
_recorded_young_cset_choice_time_ms =
(young_end_time_sec - young_start_time_sec) * 1000.0;
// We are doing young collections so reset this.
non_young_start_time_sec = young_end_time_sec;
if (!full_young_gcs()) {
bool should_continue = true;
NumberSeq seq;
double avg_prediction = 100000000000000000.0; // something very large
double prev_predicted_pause_time_ms = predicted_pause_time_ms;
do {
// Note that add_old_region_to_cset() increments the
// _old_cset_region_length field and cset_region_length() returns the
// sum of _eden_cset_region_length, _survivor_cset_region_length, and
// _old_cset_region_length. So, as old regions are added to the
// CSet, _old_cset_region_length will be incremented and
// cset_region_length(), which is used below, will always reflect
// the the total number of regions added up to this point to the CSet.
hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
avg_prediction);
if (hr != NULL) {
_g1->old_set_remove(hr);
double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
time_remaining_ms -= predicted_time_ms;
predicted_pause_time_ms += predicted_time_ms;
add_old_region_to_cset(hr);
seq.add(predicted_time_ms);
avg_prediction = seq.avg() + seq.sd();
}
should_continue = true;
if (hr == NULL) {
// No need for an ergo verbose message here,
// getNextMarkRegion() does this when it returns NULL.
should_continue = false;
} else {
if (adaptive_young_list_length()) {
if (time_remaining_ms < 0.0) {
ergo_verbose1(ErgoCSetConstruction,
"stop adding old regions to CSet",
ergo_format_reason("remaining time is lower than 0")
ergo_format_ms("remaining time"),
time_remaining_ms);
should_continue = false;
}
} else {
if (cset_region_length() >= _young_list_fixed_length) {
ergo_verbose2(ErgoCSetConstruction,
"stop adding old regions to CSet",
ergo_format_reason("CSet length reached target")
ergo_format_region("CSet")
ergo_format_region("young target"),
cset_region_length(), _young_list_fixed_length);
should_continue = false;
}
}
}
} while (should_continue);
if (!adaptive_young_list_length() &&
cset_region_length() < _young_list_fixed_length) {
ergo_verbose2(ErgoCSetConstruction,
"request partially-young GCs end",
ergo_format_reason("CSet length lower than target")
ergo_format_region("CSet")
ergo_format_region("young target"),
cset_region_length(), _young_list_fixed_length);
_should_revert_to_full_young_gcs = true;
}
ergo_verbose2(ErgoCSetConstruction | ErgoHigh,
"add old regions to CSet",
ergo_format_region("old")
ergo_format_ms("predicted old region time"),
old_cset_region_length(),
predicted_pause_time_ms - prev_predicted_pause_time_ms);
}
stop_incremental_cset_building();
count_CS_bytes_used();
ergo_verbose5(ErgoCSetConstruction,
"finish choosing CSet",
ergo_format_region("eden")
ergo_format_region("survivors")
ergo_format_region("old")
ergo_format_ms("predicted pause time")
ergo_format_ms("target pause time"),
eden_region_length, survivor_region_length,
old_cset_region_length(),
predicted_pause_time_ms, target_pause_time_ms);
double non_young_end_time_sec = os::elapsedTime();
_recorded_non_young_cset_choice_time_ms =
(non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
}