1 /*

     2  * Copyright (c) 2011, 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 import java.lang.instrument.*;

    25 import java.util.*;

    26 

    27 public class RetransformBigClassAgent {

    28     private static int N_RETRANSFORMS = 1000;

    29     public static Class clz;

    30     public static volatile boolean doneRetransforming = false;

    31 

    32     // just retransform the class in a loop via a Timer

    33     public static void premain(String agentArgs, final Instrumentation inst) throws Exception {

    34         String s = agentArgs.substring(0, agentArgs.indexOf(".class"));

    35         clz = Class.forName(s.replace('/', '.'));

    36 

    37         ClassFileTransformer trans = new SimpleIdentityTransformer();

    38         inst.addTransformer(trans, true /* canRetransform */);

    39 

    40         System.gc();  // throw away anything we can before we start testing

    41 

    42         new Timer(true).schedule(new TimerTask() {

    43             public void run() {

    44                 try {

    45                     int i;

    46                     System.out.println("Retransforming");

    47                     for (i = 0; i < N_RETRANSFORMS; i++) {

    48                         inst.retransformClasses(clz);

    49                         System.gc();  // throw away anything we can

    50                     }

    51                     System.out.println("Retransformed " + i + " times.");

    52                     RetransformBigClassAgent.doneRetransforming = true;

    53                 }

    54                 catch (Exception e) { e.printStackTrace(); }

    55             }

    56         }, 500);

    57     }

    58 }