hotspot/src/share/vm/memory/permGen.hpp
author ysr
Fri, 01 Oct 2010 16:12:54 -0700
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child 7397 5b173b4ca846
permissions -rw-r--r--
6794422: Perm gen expansion policy for concurrent collectors Summary: Concurrent collectors should expand the perm gen without a full STW GC, but possibly by triggering a concurrent collection. Temporary band-aid for G1 where no concurrent collection is kicked off since the perm gen is not collected concurrently. Reviewed-by: johnc
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/*
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 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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// All heaps contains a "permanent generation," containing permanent
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// (reflective) objects.  This is like a regular generation in some ways,
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// but unlike one in others, and so is split apart.
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class Generation;
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class GenRemSet;
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class CSpaceCounters;
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// PermGen models the part of the heap used to allocate class meta-data.
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class PermGen : public CHeapObj {
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  friend class VMStructs;
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 protected:
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  size_t _capacity_expansion_limit;  // maximum expansion allowed without a
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                                     // full gc occurring
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  void set_capacity_expansion_limit(size_t limit) {
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    assert_locked_or_safepoint(Heap_lock);
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    _capacity_expansion_limit = limit;
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  }
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  HeapWord* mem_allocate_in_gen(size_t size, Generation* gen);
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  // Along with mem_allocate_in_gen() above, implements policy for
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  // "scheduling" allocation/expansion/collection of the perm gen.
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  // The virtual method request_...() below can be overridden by
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  // subtypes that want to implement a different expansion/collection
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  // policy from the default provided.
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  virtual HeapWord* request_expand_and_allocate(Generation* gen, size_t size,
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                                                GCCause::Cause prev_cause);
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 public:
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  enum Name {
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    MarkSweepCompact, MarkSweep, ConcurrentMarkSweep
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  };
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  // Permanent allocation (initialized)
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  virtual HeapWord* mem_allocate(size_t size) = 0;
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  // Mark sweep support
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  virtual void compute_new_size() = 0;
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  // Ideally, we would use MI (IMHO) but we'll do delegation instead.
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  virtual Generation* as_gen() const = 0;
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  virtual void oop_iterate(OopClosure* cl) {
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    Generation* g = as_gen();
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    assert(g != NULL, "as_gen() NULL");
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    g->oop_iterate(cl);
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  }
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  virtual void object_iterate(ObjectClosure* cl) {
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    Generation* g = as_gen();
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    assert(g != NULL, "as_gen() NULL");
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    g->object_iterate(cl);
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  }
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  // Performance Counter support
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  virtual void update_counters() {
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    Generation* g = as_gen();
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    assert(g != NULL, "as_gen() NULL");
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    g->update_counters();
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  }
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};