/* * Copyright (c) 2001, 2016, 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/shared/adaptiveSizePolicy.hpp" #include "gc/shared/cardTableRS.hpp" #include "gc/shared/collectorPolicy.hpp" #include "gc/shared/gcLocker.inline.hpp" #include "gc/shared/gcPolicyCounters.hpp" #include "gc/shared/genCollectedHeap.hpp" #include "gc/shared/generationSpec.hpp" #include "gc/shared/space.hpp" #include "gc/shared/vmGCOperations.hpp" #include "logging/log.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" // 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()), _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, "heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT, _heap_alignment, _space_alignment); assert(_heap_alignment % _space_alignment == 0, "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"); } } // Check heap parameter properties if (MaxHeapSize < 2 * M) { vm_exit_during_initialization("Too small maximum heap"); } 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_up(_min_heap_byte_size, _heap_alignment); size_t aligned_initial_heap_size = align_up(InitialHeapSize, _heap_alignment); size_t aligned_max_heap_size = align_up(MaxHeapSize, _heap_alignment); // Write back to flags if the values changed if (aligned_initial_heap_size != InitialHeapSize) { FLAG_SET_ERGO(size_t, InitialHeapSize, aligned_initial_heap_size); } if (aligned_max_heap_size != MaxHeapSize) { FLAG_SET_ERGO(size_t, 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(size_t, MaxHeapSize, InitialHeapSize); } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) { FLAG_SET_ERGO(size_t, 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(size_t, MinHeapDeltaBytes, align_up(MinHeapDeltaBytes, _space_alignment)); DEBUG_ONLY(CollectorPolicy::assert_flags();) } void CollectorPolicy::initialize_size_info() { log_debug(gc, heap)("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; } CardTableRS* CollectorPolicy::create_rem_set(MemRegion whole_heap) { return new CardTableRS(whole_heap); } 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. size_t alignment = CardTableRS::ct_max_alignment_constraint(); if (UseLargePages) { // 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_young_size(0), _initial_young_size(0), _max_young_size(0), _min_old_size(0), _initial_old_size(0), _max_old_size(0), _gen_alignment(0), _young_gen_spec(NULL), _old_gen_spec(NULL) {} size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) { return align_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_up(3 * _space_alignment, _gen_alignment); } size_t GenCollectorPolicy::old_gen_size_lower_bound() { return align_up(_space_alignment, _gen_alignment); } #ifdef ASSERT void GenCollectorPolicy::assert_flags() { CollectorPolicy::assert_flags(); assert(NewSize >= _min_young_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"); 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_young_size, "Discrepancy between NewSize flag and local storage"); assert(MaxNewSize == _max_young_size, "Discrepancy between MaxNewSize flag and local storage"); assert(OldSize == _initial_old_size, "Discrepancy between OldSize flag and local storage"); assert(_min_young_size <= _initial_young_size, "Ergonomics decided on incompatible minimum and initial young gen sizes"); assert(_initial_young_size <= _max_young_size, "Ergonomics decided on incompatible initial and maximum young gen sizes"); assert(_min_young_size % _gen_alignment == 0, "_min_young_size alignment"); assert(_initial_young_size % _gen_alignment == 0, "_initial_young_size alignment"); assert(_max_young_size % _gen_alignment == 0, "_max_young_size alignment"); assert(_min_young_size <= bound_minus_alignment(_min_young_size, _min_heap_byte_size), "Ergonomics made minimum young generation larger than minimum heap"); assert(_initial_young_size <= bound_minus_alignment(_initial_young_size, _initial_heap_byte_size), "Ergonomics made initial young generation larger than initial heap"); assert(_max_young_size <= bound_minus_alignment(_max_young_size, _max_heap_byte_size), "Ergonomics made maximum young generation lager than maximum heap"); assert(_min_old_size <= _initial_old_size, "Ergonomics decided on incompatible minimum and initial old gen sizes"); assert(_initial_old_size <= _max_old_size, "Ergonomics decided on incompatible initial and maximum old gen sizes"); assert(_max_old_size % _gen_alignment == 0, "_max_old_size alignment"); assert(_initial_old_size % _gen_alignment == 0, "_initial_old_size alignment"); assert(_max_heap_byte_size <= (_max_young_size + _max_old_size), "Total maximum heap sizes must be sum of generation maximum sizes"); assert(_min_young_size + _min_old_size <= _min_heap_byte_size, "Minimum generation sizes exceed minimum heap size"); assert(_initial_young_size + _initial_old_size == _initial_heap_byte_size, "Initial generation sizes should match initial heap size"); assert(_max_young_size + _max_old_size == _max_heap_byte_size, "Maximum generation sizes should match maximum heap size"); } #endif // ASSERT void GenCollectorPolicy::initialize_flags() { CollectorPolicy::initialize_flags(); assert(_gen_alignment != 0, "Generation alignment not set up properly"); assert(_heap_alignment >= _gen_alignment, "heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT, _heap_alignment, _gen_alignment); assert(_gen_alignment % _space_alignment == 0, "gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT, _gen_alignment, _space_alignment); assert(_heap_alignment % _gen_alignment == 0, "heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT, _heap_alignment, _gen_alignment); // All generational heaps have a young gen; handle those flags here // Make sure the heap is large enough for two generations size_t smallest_new_size = young_gen_size_lower_bound(); size_t smallest_heap_size = align_up(smallest_new_size + old_gen_size_lower_bound(), _heap_alignment); if (MaxHeapSize < smallest_heap_size) { FLAG_SET_ERGO(size_t, 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(size_t, InitialHeapSize, smallest_heap_size); _initial_heap_byte_size = smallest_heap_size; } } // Make sure NewSize allows an old generation to fit even if set on the command line if (FLAG_IS_CMDLINE(NewSize) && NewSize >= _initial_heap_byte_size) { log_warning(gc, ergo)("NewSize was set larger than initial heap size, will use initial heap size."); FLAG_SET_ERGO(size_t, NewSize, bound_minus_alignment(NewSize, _initial_heap_byte_size)); } // Now take the actual NewSize into account. We will silently increase NewSize // if the user specified a smaller or unaligned value. size_t bounded_new_size = bound_minus_alignment(NewSize, MaxHeapSize); bounded_new_size = MAX2(smallest_new_size, align_down(bounded_new_size, _gen_alignment)); if (bounded_new_size != NewSize) { FLAG_SET_ERGO(size_t, NewSize, bounded_new_size); } _min_young_size = smallest_new_size; _initial_young_size = NewSize; if (!FLAG_IS_DEFAULT(MaxNewSize)) { if (MaxNewSize >= MaxHeapSize) { // Make sure there is room for an old generation size_t smaller_max_new_size = MaxHeapSize - _gen_alignment; if (FLAG_IS_CMDLINE(MaxNewSize)) { log_warning(gc, ergo)("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(size_t, MaxNewSize, smaller_max_new_size); if (NewSize > MaxNewSize) { FLAG_SET_ERGO(size_t, NewSize, MaxNewSize); _initial_young_size = NewSize; } } else if (MaxNewSize < _initial_young_size) { FLAG_SET_ERGO(size_t, MaxNewSize, _initial_young_size); } else if (!is_aligned(MaxNewSize, _gen_alignment)) { FLAG_SET_ERGO(size_t, MaxNewSize, align_down(MaxNewSize, _gen_alignment)); } _max_young_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)) { log_warning(gc, ergo)("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(size_t, MaxNewSize, NewSize); _max_young_size = MaxNewSize; } if (SurvivorRatio < 1 || NewRatio < 1) { vm_exit_during_initialization("Invalid young gen ratio specified"); } if (OldSize < old_gen_size_lower_bound()) { FLAG_SET_ERGO(size_t, OldSize, old_gen_size_lower_bound()); } if (!is_aligned(OldSize, _gen_alignment)) { FLAG_SET_ERGO(size_t, OldSize, align_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_up(calculated_heapsize, _heap_alignment); FLAG_SET_ERGO(size_t, MaxHeapSize, calculated_heapsize); _max_heap_byte_size = MaxHeapSize; FLAG_SET_ERGO(size_t, InitialHeapSize, calculated_heapsize); _initial_heap_byte_size = InitialHeapSize; } // Adjust NewSize and OldSize or MaxHeapSize to match each other if (NewSize + OldSize > MaxHeapSize) { if (FLAG_IS_CMDLINE(MaxHeapSize)) { // Somebody has set a maximum heap size with the intention that we should not // exceed it. Adjust New/OldSize as necessary. size_t calculated_size = NewSize + OldSize; double shrink_factor = (double) MaxHeapSize / calculated_size; size_t smaller_new_size = align_down((size_t)(NewSize * shrink_factor), _gen_alignment); FLAG_SET_ERGO(size_t, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size)); _initial_young_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(size_t, OldSize, MaxHeapSize - NewSize); } else { FLAG_SET_ERGO(size_t, MaxHeapSize, align_up(NewSize + OldSize, _heap_alignment)); _max_heap_byte_size = MaxHeapSize; } } // Update NewSize, if possible, to avoid sizing the young gen too small when only // OldSize is set on the command line. if (FLAG_IS_CMDLINE(OldSize) && !FLAG_IS_CMDLINE(NewSize)) { if (OldSize < _initial_heap_byte_size) { size_t new_size = _initial_heap_byte_size - OldSize; // Need to compare against the flag value for max since _max_young_size // might not have been set yet. if (new_size >= _min_young_size && new_size <= MaxNewSize) { FLAG_SET_ERGO(size_t, NewSize, new_size); _initial_young_size = NewSize; } } } always_do_update_barrier = UseConcMarkSweepGC; DEBUG_ONLY(GenCollectorPolicy::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. // Minimum sizes of the generations may be different than // the initial sizes. An inconsistency 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 GenCollectorPolicy::initialize_size_info() { CollectorPolicy::initialize_size_info(); _initial_young_size = NewSize; _max_young_size = MaxNewSize; _initial_old_size = OldSize; // Determine maximum size of the young generation. if (FLAG_IS_DEFAULT(MaxNewSize)) { _max_young_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_young_size = MIN2(MAX2(_max_young_size, _initial_young_size), MaxNewSize); } // Given the maximum young size, determine the initial and // minimum young sizes. if (_max_heap_byte_size == _initial_heap_byte_size) { // The maximum and initial heap sizes are the same so the generation's // initial size must be the same as it maximum size. Use NewSize as the // size if set on command line. _max_young_size = FLAG_IS_CMDLINE(NewSize) ? NewSize : _max_young_size; _initial_young_size = _max_young_size; // Also update the minimum size if min == initial == max. if (_max_heap_byte_size == _min_heap_byte_size) { _min_young_size = _max_young_size; } } else { if (FLAG_IS_CMDLINE(NewSize)) { // If NewSize is set on the command line, we should use it as // the initial size, but make sure it is within the heap bounds. _initial_young_size = MIN2(_max_young_size, bound_minus_alignment(NewSize, _initial_heap_byte_size)); _min_young_size = bound_minus_alignment(_initial_young_size, _min_heap_byte_size); } else { // For the case where NewSize is not set on the command line, use // NewRatio to size the initial generation size. Use the current // NewSize as the floor, because if NewRatio is overly large, the resulting // size can be too small. _initial_young_size = MIN2(_max_young_size, MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize)); } } log_trace(gc, heap)("1: Minimum young " SIZE_FORMAT " Initial young " SIZE_FORMAT " Maximum young " SIZE_FORMAT, _min_young_size, _initial_young_size, _max_young_size); // At this point the minimum, initial and maximum sizes // of the overall heap and of the young generation have been determined. // The maximum old size can be determined from the maximum young // and maximum heap size since no explicit flags exist // for setting the old generation maximum. _max_old_size = MAX2(_max_heap_byte_size - _max_young_size, _gen_alignment); // If no explicit command line flag has been set for the // old generation size, use what is left. 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 young sizes and the overall heap sizes. _min_old_size = _gen_alignment; _initial_old_size = MIN2(_max_old_size, MAX2(_initial_heap_byte_size - _initial_young_size, _min_old_size)); // _max_old_size has already been made consistent above. } else { // OldSize has been explicitly set on the command line. Use it // for the initial size but make sure the minimum allow a young // generation to fit as well. // 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 minimum should // be within one generation alignment. if (_initial_old_size > _max_old_size) { log_warning(gc, ergo)("Inconsistency between maximum heap size and maximum " "generation sizes: using maximum heap = " SIZE_FORMAT ", -XX:OldSize flag is being ignored", _max_heap_byte_size); _initial_old_size = _max_old_size; } _min_old_size = MIN2(_initial_old_size, _min_heap_byte_size - _min_young_size); } // The initial generation sizes should match the initial heap size, // if not issue a warning and resize the generations. This behavior // differs from JDK8 where the generation sizes have higher priority // than the initial heap size. if ((_initial_old_size + _initial_young_size) != _initial_heap_byte_size) { log_warning(gc, ergo)("Inconsistency between generation sizes and heap size, resizing " "the generations to fit the heap."); size_t desired_young_size = _initial_heap_byte_size - _initial_old_size; if (_initial_heap_byte_size < _initial_old_size) { // Old want all memory, use minimum for young and rest for old _initial_young_size = _min_young_size; _initial_old_size = _initial_heap_byte_size - _min_young_size; } else if (desired_young_size > _max_young_size) { // Need to increase both young and old generation _initial_young_size = _max_young_size; _initial_old_size = _initial_heap_byte_size - _max_young_size; } else if (desired_young_size < _min_young_size) { // Need to decrease both young and old generation _initial_young_size = _min_young_size; _initial_old_size = _initial_heap_byte_size - _min_young_size; } else { // The young generation boundaries allow us to only update the // young generation. _initial_young_size = desired_young_size; } log_trace(gc, heap)("2: Minimum young " SIZE_FORMAT " Initial young " SIZE_FORMAT " Maximum young " SIZE_FORMAT, _min_young_size, _initial_young_size, _max_young_size); } // Write back to flags if necessary. if (NewSize != _initial_young_size) { FLAG_SET_ERGO(size_t, NewSize, _initial_young_size); } if (MaxNewSize != _max_young_size) { FLAG_SET_ERGO(size_t, MaxNewSize, _max_young_size); } if (OldSize != _initial_old_size) { FLAG_SET_ERGO(size_t, OldSize, _initial_old_size); } log_trace(gc, heap)("Minimum old " SIZE_FORMAT " Initial old " SIZE_FORMAT " Maximum old " SIZE_FORMAT, _min_old_size, _initial_old_size, _max_old_size); DEBUG_ONLY(GenCollectorPolicy::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 satisfied, or unsatisfied after GC. for (uint 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 *young = gch->young_gen(); assert(young->supports_inline_contig_alloc(), "Otherwise, must do alloc within heap lock"); if (young->should_allocate(size, is_tlab)) { result = young->par_allocate(size, is_tlab); if (result != NULL) { assert(gch->is_in_reserved(result), "result not in heap"); return result; } } uint gc_count_before; // Read inside the Heap_lock locked region. { MutexLocker ml(Heap_lock); log_trace(gc, alloc)("GenCollectorPolicy::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 (GCLocker::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 GCLocker::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 = gch->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)) { log_warning(gc, ergo)("GenCollectorPolicy::mem_allocate_work retries %d times," " 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; Generation *old = gch->old_gen(); if (old->should_allocate(size, is_tlab)) { result = old->expand_and_allocate(size, is_tlab); } if (result == NULL) { Generation *young = gch->young_gen(); if (young->should_allocate(size, is_tlab)) { result = young->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 (GCLocker::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 GenCollectedHeap::OldGen); // max_generation } else { log_trace(gc)(" :: 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 GenCollectedHeap::OldGen); // max_generation } 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 GenCollectedHeap::OldGen); // max_generation } 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 = loader_data->metaspace_non_null()->allocate(word_size, mdtype); if (result != NULL) { return result; } if (GCLocker::is_active_and_needs_gc()) { // If the GCLocker 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 GCLocker::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)) { log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times," " 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 young_capacity = gch->young_gen()->capacity_before_gc(); return (word_size > heap_word_size(young_capacity)) || GCLocker::is_active_and_needs_gc() || gch->incremental_collection_failed(); } // // MarkSweepPolicy methods // void MarkSweepPolicy::initialize_alignments() { _space_alignment = _gen_alignment = (size_t)Generation::GenGrain; _heap_alignment = compute_heap_alignment(); } void MarkSweepPolicy::initialize_generations() { _young_gen_spec = new GenerationSpec(Generation::DefNew, _initial_young_size, _max_young_size, _gen_alignment); _old_gen_spec = new GenerationSpec(Generation::MarkSweepCompact, _initial_old_size, _max_old_size, _gen_alignment); } void MarkSweepPolicy::initialize_gc_policy_counters() { // Initialize the policy counters - 2 collectors, 3 generations. _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3); }