jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1StringDedupThread.hpp@e7d0505c8a30

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso

     1 /*

     2  * Copyright (c) 2014, 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

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    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPTHREAD_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPTHREAD_HPP

    28 #include "gc_implementation/g1/g1StringDedupStat.hpp"

    29 #include "gc_implementation/shared/concurrentGCThread.hpp"

    31 //

    32 // The deduplication thread is where the actual deduplication occurs. It waits for

    33 // deduplication candidates to appear on the deduplication queue, removes them from

    34 // the queue and tries to deduplicate them. It uses the deduplication hashtable to

    35 // find identical, already existing, character arrays on the heap. The thread runs

    36 // concurrently with the Java application but participates in safepoints to allow

    37 // the GC to adjust and unlink oops from the deduplication queue and table.

    38 //

    39 class G1StringDedupThread: public ConcurrentGCThread {

    40 private:

    41   static G1StringDedupThread* _thread;

    43   G1StringDedupThread();

    44   ~G1StringDedupThread();

    46   void print(outputStream* st, const G1StringDedupStat& last_stat, const G1StringDedupStat& total_stat);

    48 public:

    49   static void create();

    50   static void stop();

    52   static G1StringDedupThread* thread();

    54   virtual void run();

    55   virtual void print_on(outputStream* st) const;

    56 };

    58 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPTHREAD_HPP

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/gc_implementation/g1/g1StringDedupThread.hpp@e7d0505c8a30

src/share/vm/gc_implementation/g1/g1StringDedupThread.hpp