1 /*

     2  * Copyright (c) 2017, 2019, 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 

    25 import java.lang.instrument.ClassFileTransformer;

    26 import java.lang.instrument.Instrumentation;

    27 import java.lang.instrument.IllegalClassFormatException;

    28 import java.security.ProtectionDomain;

    29 

    30 public class GCDuringDumpTransformer implements ClassFileTransformer {

    31     public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,

    32                             ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {

    33         try {

    34             makeGarbage();

    35         } catch (Throwable t) {

    36             t.printStackTrace();

    37             try {

    38                 Thread.sleep(200); // let GC to have a chance to run

    39             } catch (Throwable t2) {}

    40         }

    41 

    42         return null;

    43     }

    44 

    45     private static Instrumentation savedInstrumentation;

    46 

    47     public static void premain(String agentArguments, Instrumentation instrumentation) {

    48         System.out.println("ClassFileTransformer.premain() is called");

    49         instrumentation.addTransformer(new GCDuringDumpTransformer(), /*canRetransform=*/true);

    50         savedInstrumentation = instrumentation;

    51     }

    52 

    53     public static Instrumentation getInstrumentation() {

    54         return savedInstrumentation;

    55     }

    56 

    57     public static void agentmain(String args, Instrumentation inst) throws Exception {

    58         premain(args, inst);

    59     }

    60 

    61     public static void makeGarbage() {

    62         for (int x=0; x<10; x++) {

    63             Object[] a = new Object[10000];

    64         }

    65     }

    66 }