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1   /* TestUtils
2   *
3   * $Id: TestUtils.java 4644 2006-09-20 22:40:21Z paul_jack $
4   *
5   * Created on Dec 28, 2004
6   *
7   * Copyright (C) 2004 Internet Archive.
8   *
9   * This file is part of the Heritrix web crawler (crawler.archive.org).
10  *
11  * Heritrix is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU Lesser Public License as published by
13  * the Free Software Foundation; either version 2.1 of the License, or
14  * any later version.
15  *
16  * Heritrix is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU Lesser Public License for more details.
20  *
21  * You should have received a copy of the GNU Lesser Public License
22  * along with Heritrix; if not, write to the Free Software
23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
24  */ 
25  package org.archive.util;
26  
27  import java.lang.ref.SoftReference;
28  import java.util.LinkedList;
29  
30  /***
31   * Utility methods useful in testing situations.
32   * 
33   * @author gojomo
34   */
35  public class TestUtils {
36  
37      /***
38       * Temporarily exhaust memory, forcing weak/soft references to
39       * be broken. 
40       */
41      public static void forceScarceMemory() {
42          // force soft references to be broken
43          LinkedList<SoftReference> hog = new LinkedList<SoftReference>();
44          long blocks = Runtime.getRuntime().maxMemory() / 1000000;
45          for(long l = 0; l <= blocks; l++) {
46              try {
47                  hog.add(new SoftReference<byte[]>(new byte[1000000]));
48              } catch (OutOfMemoryError e) {
49                  hog = null;
50                  break;
51              }
52          }
53      }
54  }