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 }