1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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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  23 
  24 /*
  25  * @test TestParallelAlwaysPreTouch
  26  * @bug 8169703
  27  * @summary Regression test to ensure AlwaysPreTouch with multiple threads works at mutator time.
  28  * Allocates a few humongous objects that will be allocated by expanding the heap, causing concurrent parallel
  29  * pre-touch.
  30  * @requires vm.gc.G1
  31  * @key gc
  32  * @key regression
  33  * @run main -Xms10M -Xmx100m -XX:G1HeapRegionSize=1M -XX:+AlwaysPreTouch -XX:PreTouchParallelChunkSize=512k -Xlog:gc+ergo+heap=debug,gc+heap=debug,gc=debug TestAlwaysPreTouch
  34  */
  35 
  36 public class Test2GbHeap {
  37   public static void main(String[] args) throws Exception {
  38     final int M = 1024 * 1024; // Something guaranteed to be larger than a region to be counted as humongous.
  39 
  40     for (int i = 0; i < 10; i++) {
  41       Object[] obj = new Object[M];
  42       System.out.println(obj);
  43     }
  44   }
  45 }
  46