/* * Copyright (c) 2001, 2014, 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/shared/adaptiveSizePolicy.hpp" #include "gc_implementation/shared/gcPolicyCounters.hpp" #include "gc_implementation/shared/vmGCOperations.hpp" #include "memory/cardTableRS.hpp" #include "memory/collectorPolicy.hpp" #include "memory/gcLocker.inline.hpp" #include "memory/genCollectedHeap.hpp" #include "memory/generationSpec.hpp" #include "memory/space.hpp" #include "memory/universe.hpp" #include "runtime/arguments.hpp" #include "runtime/globals_extension.hpp" #include "runtime/handles.inline.hpp" #include "runtime/java.hpp" #include "runtime/thread.inline.hpp" #include "runtime/vmThread.hpp" #include "utilities/macros.hpp" #if INCLUDE_ALL_GCS #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" #endif // INCLUDE_ALL_GCS // CollectorPolicy methods. CollectorPolicy::CollectorPolicy() : _space_alignment(0), _heap_alignment(0), _initial_heap_byte_size(InitialHeapSize), _max_heap_byte_size(MaxHeapSize), _min_heap_byte_size(Arguments::min_heap_size()), _max_heap_size_cmdline(false), _size_policy(NULL), _should_clear_all_soft_refs(false), _all_soft_refs_clear(false) {} #ifdef ASSERT void CollectorPolicy::assert_flags() { assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes"); assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment"); assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment"); } void CollectorPolicy::assert_size_info() { assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage"); assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage"); assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes"); assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes"); assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes"); assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment"); assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment"); assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment"); } #endif // ASSERT void CollectorPolicy::initialize_flags() { assert(_space_alignment != 0, "Space alignment not set up properly"); assert(_heap_alignment != 0, "Heap alignment not set up properly"); assert(_heap_alignment >= _space_alignment, err_msg("heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT, _heap_alignment, _space_alignment)); assert(_heap_alignment % _space_alignment == 0, err_msg("heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT, _heap_alignment, _space_alignment)); if (FLAG_IS_CMDLINE(MaxHeapSize)) { if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) { vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size"); } if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) { vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified"); } _max_heap_size_cmdline = true; } // Check heap parameter properties if (InitialHeapSize < M) { vm_exit_during_initialization("Too small initial heap"); } if (_min_heap_byte_size < M) { vm_exit_during_initialization("Too small minimum heap"); } // User inputs from -Xmx and -Xms must be aligned _min_heap_byte_size = align_size_up(_min_heap_byte_size, _heap_alignment); uintx aligned_initial_heap_size = align_size_up(InitialHeapSize, _heap_alignment); uintx aligned_max_heap_size = align_size_up(MaxHeapSize, _heap_alignment); // Write back to flags if the values changed if (aligned_initial_heap_size != InitialHeapSize) { FLAG_SET_ERGO(uintx, InitialHeapSize, aligned_initial_heap_size); } if (aligned_max_heap_size != MaxHeapSize) { FLAG_SET_ERGO(uintx, MaxHeapSize, aligned_max_heap_size); } if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 && InitialHeapSize < _min_heap_byte_size) { vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified"); } if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) { FLAG_SET_ERGO(uintx, MaxHeapSize, InitialHeapSize); } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) { FLAG_SET_ERGO(uintx, InitialHeapSize, MaxHeapSize); if (InitialHeapSize < _min_heap_byte_size) { _min_heap_byte_size = InitialHeapSize; } } _initial_heap_byte_size = InitialHeapSize; _max_heap_byte_size = MaxHeapSize; FLAG_SET_ERGO(uintx, MinHeapDeltaBytes, align_size_up(MinHeapDeltaBytes, _space_alignment)); DEBUG_ONLY(CollectorPolicy::assert_flags();) } void CollectorPolicy::initialize_size_info() { if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap " SIZE_FORMAT " Maximum heap " SIZE_FORMAT, _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size); } DEBUG_ONLY(CollectorPolicy::assert_size_info();) } bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) { bool result = _should_clear_all_soft_refs; set_should_clear_all_soft_refs(false); return result; } GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap, int max_covered_regions) { return new CardTableRS(whole_heap, max_covered_regions); } void CollectorPolicy::cleared_all_soft_refs() { // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may // have been cleared in the last collection but if the gc overhear // limit continues to be near, SoftRefs should still be cleared. if (size_policy() != NULL) { _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near(); } _all_soft_refs_clear = true; } size_t CollectorPolicy::compute_heap_alignment() { // The card marking array and the offset arrays for old generations are // committed in os pages as well. Make sure they are entirely full (to // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1 // byte entry and the os page size is 4096, the maximum heap size should // be 512*4096 = 2MB aligned. // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable // is supported. // Requirements of any new remembered set implementations must be added here. size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable); // Parallel GC does its own alignment of the generations to avoid requiring a // large page (256M on some platforms) for the permanent generation. The // other collectors should also be updated to do their own alignment and then // this use of lcm() should be removed. if (UseLargePages && !UseParallelGC) { // in presence of large pages we have to make sure that our // alignment is large page aware alignment = lcm(os::large_page_size(), alignment); } return alignment; } // GenCollectorPolicy methods. GenCollectorPolicy::GenCollectorPolicy() : _min_gen0_size(0), _initial_gen0_size(0), _max_gen0_size(0), _gen_alignment(0), _generations(NULL) {} size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) { return align_size_down_bounded(base_size / (NewRatio + 1), _gen_alignment); } size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size, size_t maximum_size) { size_t max_minus = maximum_size - _gen_alignment; return desired_size < max_minus ? desired_size : max_minus; } void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size, size_t init_promo_size, size_t init_survivor_size) { const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; _size_policy = new AdaptiveSizePolicy(init_eden_size, init_promo_size, init_survivor_size, max_gc_pause_sec, GCTimeRatio); } size_t GenCollectorPolicy::young_gen_size_lower_bound() { // The young generation must be aligned and have room for eden + two survivors return align_size_up(3 * _space_alignment, _gen_alignment); } #ifdef ASSERT void GenCollectorPolicy::assert_flags() { CollectorPolicy::assert_flags(); assert(NewSize >= _min_gen0_size, "Ergonomics decided on a too small young gen size"); assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes"); assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes"); assert(NewSize % _gen_alignment == 0, "NewSize alignment"); assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment"); } void TwoGenerationCollectorPolicy::assert_flags() { GenCollectorPolicy::assert_flags(); assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes"); assert(OldSize % _gen_alignment == 0, "OldSize alignment"); } void GenCollectorPolicy::assert_size_info() { CollectorPolicy::assert_size_info(); // GenCollectorPolicy::initialize_size_info may update the MaxNewSize assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes"); assert(NewSize == _initial_gen0_size, "Discrepancy between NewSize flag and local storage"); assert(MaxNewSize == _max_gen0_size, "Discrepancy between MaxNewSize flag and local storage"); assert(_min_gen0_size <= _initial_gen0_size, "Ergonomics decided on incompatible minimum and initial young gen sizes"); assert(_initial_gen0_size <= _max_gen0_size, "Ergonomics decided on incompatible initial and maximum young gen sizes"); assert(_min_gen0_size % _gen_alignment == 0, "_min_gen0_size alignment"); assert(_initial_gen0_size % _gen_alignment == 0, "_initial_gen0_size alignment"); assert(_max_gen0_size % _gen_alignment == 0, "_max_gen0_size alignment"); } void TwoGenerationCollectorPolicy::assert_size_info() { GenCollectorPolicy::assert_size_info(); assert(OldSize == _initial_gen1_size, "Discrepancy between OldSize flag and local storage"); assert(_min_gen1_size <= _initial_gen1_size, "Ergonomics decided on incompatible minimum and initial old gen sizes"); assert(_initial_gen1_size <= _max_gen1_size, "Ergonomics decided on incompatible initial and maximum old gen sizes"); assert(_max_gen1_size % _gen_alignment == 0, "_max_gen1_size alignment"); assert(_initial_gen1_size % _gen_alignment == 0, "_initial_gen1_size alignment"); assert(_max_heap_byte_size <= (_max_gen0_size + _max_gen1_size), "Total maximum heap sizes must be sum of generation maximum sizes"); } #endif // ASSERT void GenCollectorPolicy::initialize_flags() { CollectorPolicy::initialize_flags(); assert(_gen_alignment != 0, "Generation alignment not set up properly"); assert(_heap_alignment >= _gen_alignment, err_msg("heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT, _heap_alignment, _gen_alignment)); assert(_gen_alignment % _space_alignment == 0, err_msg("gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT, _gen_alignment, _space_alignment)); assert(_heap_alignment % _gen_alignment == 0, err_msg("heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT, _heap_alignment, _gen_alignment)); // All generational heaps have a youngest gen; handle those flags here // Make sure the heap is large enough for two generations uintx smallest_new_size = young_gen_size_lower_bound(); uintx smallest_heap_size = align_size_up(smallest_new_size + align_size_up(_space_alignment, _gen_alignment), _heap_alignment); if (MaxHeapSize < smallest_heap_size) { FLAG_SET_ERGO(uintx, MaxHeapSize, smallest_heap_size); _max_heap_byte_size = MaxHeapSize; } // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size if (_min_heap_byte_size < smallest_heap_size) { _min_heap_byte_size = smallest_heap_size; if (InitialHeapSize < _min_heap_byte_size) { FLAG_SET_ERGO(uintx, InitialHeapSize, smallest_heap_size); _initial_heap_byte_size = smallest_heap_size; } } // Now take the actual NewSize into account. We will silently increase NewSize // if the user specified a smaller or unaligned value. smallest_new_size = MAX2(smallest_new_size, (uintx)align_size_down(NewSize, _gen_alignment)); if (smallest_new_size != NewSize) { // Do not use FLAG_SET_ERGO to update NewSize here, since this will override // if NewSize was set on the command line or not. This information is needed // later when setting the initial and minimum young generation size. NewSize = smallest_new_size; } _initial_gen0_size = NewSize; if (!FLAG_IS_DEFAULT(MaxNewSize)) { uintx min_new_size = MAX2(_gen_alignment, _min_gen0_size); if (MaxNewSize >= MaxHeapSize) { // Make sure there is room for an old generation uintx smaller_max_new_size = MaxHeapSize - _gen_alignment; if (FLAG_IS_CMDLINE(MaxNewSize)) { warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire " "heap (" SIZE_FORMAT "k). A new max generation size of " SIZE_FORMAT "k will be used.", MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K); } FLAG_SET_ERGO(uintx, MaxNewSize, smaller_max_new_size); if (NewSize > MaxNewSize) { FLAG_SET_ERGO(uintx, NewSize, MaxNewSize); _initial_gen0_size = NewSize; } } else if (MaxNewSize < min_new_size) { FLAG_SET_ERGO(uintx, MaxNewSize, min_new_size); } else if (!is_size_aligned(MaxNewSize, _gen_alignment)) { FLAG_SET_ERGO(uintx, MaxNewSize, align_size_down(MaxNewSize, _gen_alignment)); } _max_gen0_size = MaxNewSize; } if (NewSize > MaxNewSize) { // At this point this should only happen if the user specifies a large NewSize and/or // a small (but not too small) MaxNewSize. if (FLAG_IS_CMDLINE(MaxNewSize)) { warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). " "A new max generation size of " SIZE_FORMAT "k will be used.", NewSize/K, MaxNewSize/K, NewSize/K); } FLAG_SET_ERGO(uintx, MaxNewSize, NewSize); _max_gen0_size = MaxNewSize; } if (SurvivorRatio < 1 || NewRatio < 1) { vm_exit_during_initialization("Invalid young gen ratio specified"); } DEBUG_ONLY(GenCollectorPolicy::assert_flags();) } void TwoGenerationCollectorPolicy::initialize_flags() { GenCollectorPolicy::initialize_flags(); if (!is_size_aligned(OldSize, _gen_alignment)) { FLAG_SET_ERGO(uintx, OldSize, align_size_down(OldSize, _gen_alignment)); } if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) { // NewRatio will be used later to set the young generation size so we use // it to calculate how big the heap should be based on the requested OldSize // and NewRatio. assert(NewRatio > 0, "NewRatio should have been set up earlier"); size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1); calculated_heapsize = align_size_up(calculated_heapsize, _heap_alignment); FLAG_SET_ERGO(uintx, MaxHeapSize, calculated_heapsize); _max_heap_byte_size = MaxHeapSize; FLAG_SET_ERGO(uintx, InitialHeapSize, calculated_heapsize); _initial_heap_byte_size = InitialHeapSize; } // adjust max heap size if necessary if (NewSize + OldSize > MaxHeapSize) { if (_max_heap_size_cmdline) { // somebody set a maximum heap size with the intention that we should not // exceed it. Adjust New/OldSize as necessary. uintx calculated_size = NewSize + OldSize; double shrink_factor = (double) MaxHeapSize / calculated_size; uintx smaller_new_size = align_size_down((uintx)(NewSize * shrink_factor), _gen_alignment); FLAG_SET_ERGO(uintx, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size)); _initial_gen0_size = NewSize; // OldSize is already aligned because above we aligned MaxHeapSize to // _heap_alignment, and we just made sure that NewSize is aligned to // _gen_alignment. In initialize_flags() we verified that _heap_alignment // is a multiple of _gen_alignment. FLAG_SET_ERGO(uintx, OldSize, MaxHeapSize - NewSize); } else { FLAG_SET_ERGO(uintx, MaxHeapSize, align_size_up(NewSize + OldSize, _heap_alignment)); _max_heap_byte_size = MaxHeapSize; } } always_do_update_barrier = UseConcMarkSweepGC; DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_flags();) } // Values set on the command line win over any ergonomically // set command line parameters. // Ergonomic choice of parameters are done before this // method is called. Values for command line parameters such as NewSize // and MaxNewSize feed those ergonomic choices into this method. // This method makes the final generation sizings consistent with // themselves and with overall heap sizings. // In the absence of explicitly set command line flags, policies // such as the use of NewRatio are used to size the generation. void GenCollectorPolicy::initialize_size_info() { CollectorPolicy::initialize_size_info(); // _space_alignment is used for alignment within a generation. // There is additional alignment done down stream for some // collectors that sometimes causes unwanted rounding up of // generations sizes. // Determine maximum size of gen0 size_t max_new_size = 0; if (!FLAG_IS_DEFAULT(MaxNewSize)) { max_new_size = MaxNewSize; } else { max_new_size = scale_by_NewRatio_aligned(_max_heap_byte_size); // Bound the maximum size by NewSize below (since it historically // would have been NewSize and because the NewRatio calculation could // yield a size that is too small) and bound it by MaxNewSize above. // Ergonomics plays here by previously calculating the desired // NewSize and MaxNewSize. max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize); } assert(max_new_size > 0, "All paths should set max_new_size"); // Given the maximum gen0 size, determine the initial and // minimum gen0 sizes. if (_max_heap_byte_size == _min_heap_byte_size) { // The maximum and minimum heap sizes are the same so // the generations minimum and initial must be the // same as its maximum. _min_gen0_size = max_new_size; _initial_gen0_size = max_new_size; _max_gen0_size = max_new_size; } else { size_t desired_new_size = 0; if (FLAG_IS_CMDLINE(NewSize)) { // If NewSize is set on the command line, we must use it as // the initial size and it also makes sense to use it as the // lower limit. _min_gen0_size = NewSize; desired_new_size = NewSize; max_new_size = MAX2(max_new_size, NewSize); } else if (FLAG_IS_ERGO(NewSize)) { // If NewSize is set ergonomically, we should use it as a lower // limit, but use NewRatio to calculate the initial size. _min_gen0_size = NewSize; desired_new_size = MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize); max_new_size = MAX2(max_new_size, NewSize); } else { // For the case where NewSize is the default, use NewRatio // to size the minimum and initial generation sizes. // Use the default NewSize as the floor for these values. If // NewRatio is overly large, the resulting sizes can be too // small. _min_gen0_size = MAX2(scale_by_NewRatio_aligned(_min_heap_byte_size), NewSize); desired_new_size = MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize); } assert(_min_gen0_size > 0, "Sanity check"); _initial_gen0_size = desired_new_size; _max_gen0_size = max_new_size; // At this point the desirable initial and minimum sizes have been // determined without regard to the maximum sizes. // Bound the sizes by the corresponding overall heap sizes. _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size); _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size); _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size); // At this point all three sizes have been checked against the // maximum sizes but have not been checked for consistency // among the three. // Final check min <= initial <= max _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size); _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size); _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size); } // Write back to flags if necessary if (NewSize != _initial_gen0_size) { FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size); } if (MaxNewSize != _max_gen0_size) { FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size); } if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 " SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, _min_gen0_size, _initial_gen0_size, _max_gen0_size); } DEBUG_ONLY(GenCollectorPolicy::assert_size_info();) } // Call this method during the sizing of the gen1 to make // adjustments to gen0 because of gen1 sizing policy. gen0 initially has // the most freedom in sizing because it is done before the // policy for gen1 is applied. Once gen1 policies have been applied, // there may be conflicts in the shape of the heap and this method // is used to make the needed adjustments. The application of the // policies could be more sophisticated (iterative for example) but // keeping it simple also seems a worthwhile goal. bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr, const size_t heap_size) { bool result = false; if ((*gen0_size_ptr + *gen1_size_ptr) > heap_size) { uintx smallest_new_size = young_gen_size_lower_bound(); if ((heap_size < (*gen0_size_ptr + _min_gen1_size)) && (heap_size >= _min_gen1_size + smallest_new_size)) { // Adjust gen0 down to accommodate _min_gen1_size *gen0_size_ptr = align_size_down_bounded(heap_size - _min_gen1_size, _gen_alignment); result = true; } else { *gen1_size_ptr = align_size_down_bounded(heap_size - *gen0_size_ptr, _gen_alignment); } } return result; } // Minimum sizes of the generations may be different than // the initial sizes. An inconsistently is permitted here // in the total size that can be specified explicitly by // command line specification of OldSize and NewSize and // also a command line specification of -Xms. Issue a warning // but allow the values to pass. void TwoGenerationCollectorPolicy::initialize_size_info() { GenCollectorPolicy::initialize_size_info(); // At this point the minimum, initial and maximum sizes // of the overall heap and of gen0 have been determined. // The maximum gen1 size can be determined from the maximum gen0 // and maximum heap size since no explicit flags exits // for setting the gen1 maximum. _max_gen1_size = MAX2(_max_heap_byte_size - _max_gen0_size, _gen_alignment); // If no explicit command line flag has been set for the // gen1 size, use what is left for gen1. if (!FLAG_IS_CMDLINE(OldSize)) { // The user has not specified any value but the ergonomics // may have chosen a value (which may or may not be consistent // with the overall heap size). In either case make // the minimum, maximum and initial sizes consistent // with the gen0 sizes and the overall heap sizes. _min_gen1_size = MAX2(_min_heap_byte_size - _min_gen0_size, _gen_alignment); _initial_gen1_size = MAX2(_initial_heap_byte_size - _initial_gen0_size, _gen_alignment); // _max_gen1_size has already been made consistent above FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size); } else { // It's been explicitly set on the command line. Use the // OldSize and then determine the consequences. _min_gen1_size = MIN2(OldSize, _min_heap_byte_size - _min_gen0_size); _initial_gen1_size = OldSize; // If the user has explicitly set an OldSize that is inconsistent // with other command line flags, issue a warning. // The generation minimums and the overall heap mimimum should // be within one generation alignment. if ((_min_gen1_size + _min_gen0_size + _gen_alignment) < _min_heap_byte_size) { warning("Inconsistency between minimum heap size and minimum " "generation sizes: using minimum heap = " SIZE_FORMAT, _min_heap_byte_size); } if (OldSize > _max_gen1_size) { warning("Inconsistency between maximum heap size and maximum " "generation sizes: using maximum heap = " SIZE_FORMAT " -XX:OldSize flag is being ignored", _max_heap_byte_size); } // If there is an inconsistency between the OldSize and the minimum and/or // initial size of gen0, since OldSize was explicitly set, OldSize wins. if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size, _min_heap_byte_size)) { if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 " SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, _min_gen0_size, _initial_gen0_size, _max_gen0_size); } } // Initial size if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size, _initial_heap_byte_size)) { if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 " SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, _min_gen0_size, _initial_gen0_size, _max_gen0_size); } } } // Enforce the maximum gen1 size. _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size); // Check that min gen1 <= initial gen1 <= max gen1 _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size); _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size); // Write back to flags if necessary if (NewSize != _initial_gen0_size) { FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size); } if (MaxNewSize != _max_gen0_size) { FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size); } if (OldSize != _initial_gen1_size) { FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size); } if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 " SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT, _min_gen1_size, _initial_gen1_size, _max_gen1_size); } DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_size_info();) } HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size, bool is_tlab, bool* gc_overhead_limit_was_exceeded) { GenCollectedHeap *gch = GenCollectedHeap::heap(); debug_only(gch->check_for_valid_allocation_state()); assert(gch->no_gc_in_progress(), "Allocation during gc not allowed"); // In general gc_overhead_limit_was_exceeded should be false so // set it so here and reset it to true only if the gc time // limit is being exceeded as checked below. *gc_overhead_limit_was_exceeded = false; HeapWord* result = NULL; // Loop until the allocation is satisified, // or unsatisfied after GC. for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { HandleMark hm; // discard any handles allocated in each iteration // First allocation attempt is lock-free. Generation *gen0 = gch->get_gen(0); assert(gen0->supports_inline_contig_alloc(), "Otherwise, must do alloc within heap lock"); if (gen0->should_allocate(size, is_tlab)) { result = gen0->par_allocate(size, is_tlab); if (result != NULL) { assert(gch->is_in_reserved(result), "result not in heap"); return result; } } unsigned int gc_count_before; // read inside the Heap_lock locked region { MutexLocker ml(Heap_lock); if (PrintGC && Verbose) { gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:" " attempting locked slow path allocation"); } // Note that only large objects get a shot at being // allocated in later generations. bool first_only = ! should_try_older_generation_allocation(size); result = gch->attempt_allocation(size, is_tlab, first_only); if (result != NULL) { assert(gch->is_in_reserved(result), "result not in heap"); return result; } if (GC_locker::is_active_and_needs_gc()) { if (is_tlab) { return NULL; // Caller will retry allocating individual object } if (!gch->is_maximal_no_gc()) { // Try and expand heap to satisfy request result = expand_heap_and_allocate(size, is_tlab); // result could be null if we are out of space if (result != NULL) { return result; } } if (gclocker_stalled_count > GCLockerRetryAllocationCount) { return NULL; // we didn't get to do a GC and we didn't get any memory } // If this thread is not in a jni critical section, we stall // the requestor until the critical section has cleared and // GC allowed. When the critical section clears, a GC is // initiated by the last thread exiting the critical section; so // we retry the allocation sequence from the beginning of the loop, // rather than causing more, now probably unnecessary, GC attempts. JavaThread* jthr = JavaThread::current(); if (!jthr->in_critical()) { MutexUnlocker mul(Heap_lock); // Wait for JNI critical section to be exited GC_locker::stall_until_clear(); gclocker_stalled_count += 1; continue; } else { if (CheckJNICalls) { fatal("Possible deadlock due to allocating while" " in jni critical section"); } return NULL; } } // Read the gc count while the heap lock is held. gc_count_before = Universe::heap()->total_collections(); } VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); VMThread::execute(&op); if (op.prologue_succeeded()) { result = op.result(); if (op.gc_locked()) { assert(result == NULL, "must be NULL if gc_locked() is true"); continue; // retry and/or stall as necessary } // Allocation has failed and a collection // has been done. If the gc time limit was exceeded the // this time, return NULL so that an out-of-memory // will be thrown. Clear gc_overhead_limit_exceeded // so that the overhead exceeded does not persist. const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); const bool softrefs_clear = all_soft_refs_clear(); if (limit_exceeded && softrefs_clear) { *gc_overhead_limit_was_exceeded = true; size_policy()->set_gc_overhead_limit_exceeded(false); if (op.result() != NULL) { CollectedHeap::fill_with_object(op.result(), size); } return NULL; } assert(result == NULL || gch->is_in_reserved(result), "result not in heap"); return result; } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t" " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); } } } HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size, bool is_tlab) { GenCollectedHeap *gch = GenCollectedHeap::heap(); HeapWord* result = NULL; for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) { Generation *gen = gch->get_gen(i); if (gen->should_allocate(size, is_tlab)) { result = gen->expand_and_allocate(size, is_tlab); } } assert(result == NULL || gch->is_in_reserved(result), "result not in heap"); return result; } HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size, bool is_tlab) { GenCollectedHeap *gch = GenCollectedHeap::heap(); GCCauseSetter x(gch, GCCause::_allocation_failure); HeapWord* result = NULL; assert(size != 0, "Precondition violated"); if (GC_locker::is_active_and_needs_gc()) { // GC locker is active; instead of a collection we will attempt // to expand the heap, if there's room for expansion. if (!gch->is_maximal_no_gc()) { result = expand_heap_and_allocate(size, is_tlab); } return result; // could be null if we are out of space } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) { // Do an incremental collection. gch->do_collection(false /* full */, false /* clear_all_soft_refs */, size /* size */, is_tlab /* is_tlab */, number_of_generations() - 1 /* max_level */); } else { if (Verbose && PrintGCDetails) { gclog_or_tty->print(" :: Trying full because partial may fail :: "); } // Try a full collection; see delta for bug id 6266275 // for the original code and why this has been simplified // with from-space allocation criteria modified and // such allocation moved out of the safepoint path. gch->do_collection(true /* full */, false /* clear_all_soft_refs */, size /* size */, is_tlab /* is_tlab */, number_of_generations() - 1 /* max_level */); } result = gch->attempt_allocation(size, is_tlab, false /*first_only*/); if (result != NULL) { assert(gch->is_in_reserved(result), "result not in heap"); return result; } // OK, collection failed, try expansion. result = expand_heap_and_allocate(size, is_tlab); if (result != NULL) { return result; } // If we reach this point, we're really out of memory. Try every trick // we can to reclaim memory. Force collection of soft references. Force // a complete compaction of the heap. Any additional methods for finding // free memory should be here, especially if they are expensive. If this // attempt fails, an OOM exception will be thrown. { UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted gch->do_collection(true /* full */, true /* clear_all_soft_refs */, size /* size */, is_tlab /* is_tlab */, number_of_generations() - 1 /* max_level */); } result = gch->attempt_allocation(size, is_tlab, false /* first_only */); if (result != NULL) { assert(gch->is_in_reserved(result), "result not in heap"); return result; } assert(!should_clear_all_soft_refs(), "Flag should have been handled and cleared prior to this point"); // What else? We might try synchronous finalization later. If the total // space available is large enough for the allocation, then a more // complete compaction phase than we've tried so far might be // appropriate. return NULL; } MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation( ClassLoaderData* loader_data, size_t word_size, Metaspace::MetadataType mdtype) { uint loop_count = 0; uint gc_count = 0; uint full_gc_count = 0; assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock"); do { MetaWord* result = NULL; if (GC_locker::is_active_and_needs_gc()) { // If the GC_locker is active, just expand and allocate. // If that does not succeed, wait if this thread is not // in a critical section itself. result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype); if (result != NULL) { return result; } JavaThread* jthr = JavaThread::current(); if (!jthr->in_critical()) { // Wait for JNI critical section to be exited GC_locker::stall_until_clear(); // The GC invoked by the last thread leaving the critical // section will be a young collection and a full collection // is (currently) needed for unloading classes so continue // to the next iteration to get a full GC. continue; } else { if (CheckJNICalls) { fatal("Possible deadlock due to allocating while" " in jni critical section"); } return NULL; } } { // Need lock to get self consistent gc_count's MutexLocker ml(Heap_lock); gc_count = Universe::heap()->total_collections(); full_gc_count = Universe::heap()->total_full_collections(); } // Generate a VM operation VM_CollectForMetadataAllocation op(loader_data, word_size, mdtype, gc_count, full_gc_count, GCCause::_metadata_GC_threshold); VMThread::execute(&op); // If GC was locked out, try again. Check // before checking success because the prologue // could have succeeded and the GC still have // been locked out. if (op.gc_locked()) { continue; } if (op.prologue_succeeded()) { return op.result(); } loop_count++; if ((QueuedAllocationWarningCount > 0) && (loop_count % QueuedAllocationWarningCount == 0)) { warning("satisfy_failed_metadata_allocation() retries %d times \n\t" " size=" SIZE_FORMAT, loop_count, word_size); } } while (true); // Until a GC is done } // Return true if any of the following is true: // . the allocation won't fit into the current young gen heap // . gc locker is occupied (jni critical section) // . heap memory is tight -- the most recent previous collection // was a full collection because a partial collection (would // have) failed and is likely to fail again bool GenCollectorPolicy::should_try_older_generation_allocation( size_t word_size) const { GenCollectedHeap* gch = GenCollectedHeap::heap(); size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc(); return (word_size > heap_word_size(gen0_capacity)) || GC_locker::is_active_and_needs_gc() || gch->incremental_collection_failed(); } // // MarkSweepPolicy methods // void MarkSweepPolicy::initialize_alignments() { _space_alignment = _gen_alignment = (uintx)Generation::GenGrain; _heap_alignment = compute_heap_alignment(); } void MarkSweepPolicy::initialize_generations() { _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL); if (_generations == NULL) { vm_exit_during_initialization("Unable to allocate gen spec"); } if (UseParNewGC) { _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size); } else { _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size); } _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size); if (_generations[0] == NULL || _generations[1] == NULL) { vm_exit_during_initialization("Unable to allocate gen spec"); } } void MarkSweepPolicy::initialize_gc_policy_counters() { // initialize the policy counters - 2 collectors, 3 generations if (UseParNewGC) { _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3); } else { _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3); } } /////////////// Unit tests /////////////// #ifndef PRODUCT // Testing that the NewSize flag is handled correct is hard because it // depends on so many other configurable variables. This test only tries to // verify that there are some basic rules for NewSize honored by the policies. class TestGenCollectorPolicy { public: static void test() { size_t flag_value; save_flags(); // Set some limits that makes the math simple. FLAG_SET_ERGO(uintx, MaxHeapSize, 180 * M); FLAG_SET_ERGO(uintx, InitialHeapSize, 120 * M); Arguments::set_min_heap_size(40 * M); // If NewSize is set on the command line, it should be used // for both min and initial young size if less than min heap. flag_value = 20 * M; FLAG_SET_CMDLINE(uintx, NewSize, flag_value); verify_min(flag_value); verify_initial(flag_value); // If NewSize is set on command line, but is larger than the min // heap size, it should only be used for initial young size. flag_value = 80 * M; FLAG_SET_CMDLINE(uintx, NewSize, flag_value); verify_initial(flag_value); // If NewSize has been ergonomically set, the collector policy // should use it for min but calculate the initial young size // using NewRatio. flag_value = 20 * M; FLAG_SET_ERGO(uintx, NewSize, flag_value); verify_min(flag_value); verify_scaled_initial(InitialHeapSize); restore_flags(); } static void verify_min(size_t expected) { MarkSweepPolicy msp; msp.initialize_all(); assert(msp.min_gen0_size() <= expected, err_msg("%zu > %zu", msp.min_gen0_size(), expected)); } static void verify_initial(size_t expected) { MarkSweepPolicy msp; msp.initialize_all(); assert(msp.initial_gen0_size() == expected, err_msg("%zu != %zu", msp.initial_gen0_size(), expected)); } static void verify_scaled_initial(size_t initial_heap_size) { MarkSweepPolicy msp; msp.initialize_all(); size_t expected = msp.scale_by_NewRatio_aligned(initial_heap_size); assert(msp.initial_gen0_size() == expected, err_msg("%zu != %zu", msp.initial_gen0_size(), expected)); assert(FLAG_IS_ERGO(NewSize) && NewSize == expected, err_msg("NewSize should have been set ergonomically to %zu, but was %zu", expected, NewSize)); } private: static size_t original_InitialHeapSize; static size_t original_MaxHeapSize; static size_t original_MaxNewSize; static size_t original_MinHeapDeltaBytes; static size_t original_NewSize; static size_t original_OldSize; static void save_flags() { original_InitialHeapSize = InitialHeapSize; original_MaxHeapSize = MaxHeapSize; original_MaxNewSize = MaxNewSize; original_MinHeapDeltaBytes = MinHeapDeltaBytes; original_NewSize = NewSize; original_OldSize = OldSize; } static void restore_flags() { InitialHeapSize = original_InitialHeapSize; MaxHeapSize = original_MaxHeapSize; MaxNewSize = original_MaxNewSize; MinHeapDeltaBytes = original_MinHeapDeltaBytes; NewSize = original_NewSize; OldSize = original_OldSize; } }; size_t TestGenCollectorPolicy::original_InitialHeapSize = 0; size_t TestGenCollectorPolicy::original_MaxHeapSize = 0; size_t TestGenCollectorPolicy::original_MaxNewSize = 0; size_t TestGenCollectorPolicy::original_MinHeapDeltaBytes = 0; size_t TestGenCollectorPolicy::original_NewSize = 0; size_t TestGenCollectorPolicy::original_OldSize = 0; void TestNewSize_test() { TestGenCollectorPolicy::test(); } #endif