Mercurial > hg > truffle
view src/share/vm/memory/permGen.cpp @ 453:c96030fff130
6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa
author | ysr |
---|---|
date | Thu, 20 Nov 2008 16:56:09 -0800 |
parents | d1605aabd0a1 |
children | d249b360e026 |
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/* * Copyright 2000-2008 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ #include "incls/_precompiled.incl" #include "incls/_permGen.cpp.incl" HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) { MutexLocker ml(Heap_lock); GCCause::Cause next_cause = GCCause::_permanent_generation_full; GCCause::Cause prev_cause = GCCause::_no_gc; for (;;) { HeapWord* obj = gen->allocate(size, false); if (obj != NULL) { return obj; } if (gen->capacity() < _capacity_expansion_limit || prev_cause != GCCause::_no_gc) { obj = gen->expand_and_allocate(size, false); } if (obj == NULL && prev_cause != GCCause::_last_ditch_collection) { if (GC_locker::is_active_and_needs_gc()) { // 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(); continue; } else { if (CheckJNICalls) { fatal("Possible deadlock due to allocating while" " in jni critical section"); } return NULL; } } // Read the GC count while holding the Heap_lock unsigned int gc_count_before = SharedHeap::heap()->total_collections(); unsigned int full_gc_count_before = SharedHeap::heap()->total_full_collections(); { MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before, next_cause); VMThread::execute(&op); if (!op.prologue_succeeded() || op.gc_locked()) { assert(op.result() == NULL, "must be NULL if gc_locked() is true"); continue; // retry and/or stall as necessary } obj = op.result(); assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj), "result not in heap"); if (obj != NULL) { return obj; } } prev_cause = next_cause; next_cause = GCCause::_last_ditch_collection; } else { return obj; } } } CompactingPermGen::CompactingPermGen(ReservedSpace rs, ReservedSpace shared_rs, size_t initial_byte_size, GenRemSet* remset, PermanentGenerationSpec* perm_spec) { CompactingPermGenGen* g = new CompactingPermGenGen(rs, shared_rs, initial_byte_size, -1, remset, NULL, perm_spec); if (g == NULL) vm_exit_during_initialization("Could not allocate a CompactingPermGen"); _gen = g; g->initialize_performance_counters(); _capacity_expansion_limit = g->capacity() + MaxPermHeapExpansion; } HeapWord* CompactingPermGen::mem_allocate(size_t size) { return mem_allocate_in_gen(size, _gen); } void CompactingPermGen::compute_new_size() { size_t desired_capacity = align_size_up(_gen->used(), MinPermHeapExpansion); if (desired_capacity < PermSize) { desired_capacity = PermSize; } if (_gen->capacity() > desired_capacity) { _gen->shrink(_gen->capacity() - desired_capacity); } _capacity_expansion_limit = _gen->capacity() + MaxPermHeapExpansion; }