1 /* 2 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc_implementation/shared/cSpaceCounters.hpp" 27 #include "gc_implementation/shared/vmGCOperations.hpp" 28 #include "gc_interface/collectedHeap.inline.hpp" 29 #include "memory/blockOffsetTable.inline.hpp" 30 #include "memory/compactPermGen.hpp" 31 #include "memory/gcLocker.hpp" 32 #include "memory/gcLocker.inline.hpp" 33 #include "memory/genCollectedHeap.hpp" 34 #include "memory/generation.inline.hpp" 35 #include "memory/permGen.hpp" 36 #include "memory/universe.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "runtime/java.hpp" 39 #include "runtime/vmThread.hpp" 40 41 HeapWord* PermGen::request_expand_and_allocate(Generation* gen, size_t size, 42 GCCause::Cause prev_cause) { 43 if (gen->capacity() < _capacity_expansion_limit || 44 prev_cause != GCCause::_no_gc || UseG1GC) { // last disjunct is a temporary hack for G1 45 return gen->expand_and_allocate(size, false); 46 } 47 // We have reached the limit of capacity expansion where 48 // we will not expand further until a GC is done; request denied. 49 return NULL; 50 } 51 52 HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) { 53 GCCause::Cause next_cause = GCCause::_permanent_generation_full; 54 GCCause::Cause prev_cause = GCCause::_no_gc; 55 unsigned int gc_count_before, full_gc_count_before; 56 HeapWord* obj; 57 58 for (;;) { 59 { 60 MutexLocker ml(Heap_lock); 61 if ((obj = gen->allocate(size, false)) != NULL) { 62 return obj; 63 } 64 // Attempt to expand and allocate the requested space: 65 // specific subtypes may use specific policy to either expand 66 // or not. The default policy (see above) is to expand until 67 // _capacity_expansion_limit, and no further unless a GC is done. 68 // Concurrent collectors may decide to kick off a concurrent 69 // collection under appropriate conditions. 70 obj = request_expand_and_allocate(gen, size, prev_cause); 71 72 if (obj != NULL || prev_cause == GCCause::_last_ditch_collection) { 73 return obj; 74 } 75 if (GC_locker::is_active_and_needs_gc()) { 76 // If this thread is not in a jni critical section, we stall 77 // the requestor until the critical section has cleared and 78 // GC allowed. When the critical section clears, a GC is 79 // initiated by the last thread exiting the critical section; so 80 // we retry the allocation sequence from the beginning of the loop, 81 // rather than causing more, now probably unnecessary, GC attempts. 82 JavaThread* jthr = JavaThread::current(); 83 if (!jthr->in_critical()) { 84 MutexUnlocker mul(Heap_lock); 85 // Wait for JNI critical section to be exited 86 GC_locker::stall_until_clear(); 87 continue; 88 } else { 89 if (CheckJNICalls) { 90 fatal("Possible deadlock due to allocating while" 91 " in jni critical section"); 92 } 93 return NULL; 94 } 95 } 96 // Read the GC count while holding the Heap_lock 97 gc_count_before = SharedHeap::heap()->total_collections(); 98 full_gc_count_before = SharedHeap::heap()->total_full_collections(); 99 } 100 101 // Give up heap lock above, VMThread::execute below gets it back 102 VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before, 103 next_cause); 104 VMThread::execute(&op); 105 if (!op.prologue_succeeded() || op.gc_locked()) { 106 assert(op.result() == NULL, "must be NULL if gc_locked() is true"); 107 continue; // retry and/or stall as necessary 108 } 109 obj = op.result(); 110 assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj), 111 "result not in heap"); 112 if (obj != NULL) { 113 return obj; 114 } 115 prev_cause = next_cause; 116 next_cause = GCCause::_last_ditch_collection; 117 } 118 } 119 120 CompactingPermGen::CompactingPermGen(ReservedSpace rs, 121 ReservedSpace shared_rs, 122 size_t initial_byte_size, 123 GenRemSet* remset, 124 PermanentGenerationSpec* perm_spec) 125 { 126 CompactingPermGenGen* g = 127 new CompactingPermGenGen(rs, shared_rs, initial_byte_size, -1, remset, 128 NULL, perm_spec); 129 if (g == NULL) 130 vm_exit_during_initialization("Could not allocate a CompactingPermGen"); 131 _gen = g; 132 133 g->initialize_performance_counters(); 134 135 _capacity_expansion_limit = g->capacity() + MaxPermHeapExpansion; 136 } 137 138 HeapWord* CompactingPermGen::mem_allocate(size_t size) { 139 return mem_allocate_in_gen(size, _gen); 140 } 141 142 void CompactingPermGen::compute_new_size() { 143 size_t desired_capacity = align_size_up(_gen->used(), MinPermHeapExpansion); 144 if (desired_capacity < PermSize) { 145 desired_capacity = PermSize; 146 } 147 if (_gen->capacity() > desired_capacity) { 148 _gen->shrink(_gen->capacity() - desired_capacity); 149 } 150 set_capacity_expansion_limit(_gen->capacity() + MaxPermHeapExpansion); 151 }