1 /* 2 * Copyright (c) 2017, 2020, 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.lang.ref.Cleaner; 29 import java.security.ProtectionDomain; 30 31 public class GCDuringDumpTransformer implements ClassFileTransformer { 32 static boolean TEST_WITH_CLEANER = Boolean.getBoolean("test.with.cleaner"); 33 static Cleaner cleaner; 34 static Thread thread; 35 static Object garbage; 36 37 static { 38 if (TEST_WITH_CLEANER) { 39 cleaner = Cleaner.create(); 40 garbage = new Object(); 41 cleaner.register(garbage, new MyCleaner()); 42 System.out.println("Registered cleaner"); 43 } 44 } 45 46 public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined, 47 ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException { 48 if (TEST_WITH_CLEANER) { 49 if (name.equals("Hello")) { 50 garbage = null; 51 System.out.println("Unreferenced GCDuringDumpTransformer.garbage"); 52 } 53 } else { 54 try { 55 makeGarbage(); 56 } catch (Throwable t) { 57 t.printStackTrace(); 58 try { 59 Thread.sleep(200); // let GC to have a chance to run 60 } catch (Throwable t2) {} 61 } 62 } 63 64 return null; 65 } 66 67 private static Instrumentation savedInstrumentation; 68 69 public static void premain(String agentArguments, Instrumentation instrumentation) { 70 System.out.println("ClassFileTransformer.premain() is called: TEST_WITH_CLEANER = " + TEST_WITH_CLEANER); 71 instrumentation.addTransformer(new GCDuringDumpTransformer(), /*canRetransform=*/true); 72 savedInstrumentation = instrumentation; 73 } 74 75 public static Instrumentation getInstrumentation() { 76 return savedInstrumentation; 77 } 78 79 public static void agentmain(String args, Instrumentation inst) throws Exception { 80 premain(args, inst); 81 } 82 83 public static void makeGarbage() { 84 for (int x=0; x<10; x++) { 85 Object[] a = new Object[10000]; 86 } 87 } 88 89 static class MyCleaner implements Runnable { 90 static int count = 0; 91 int i = count++; 92 public void run() { 93 // Allocate something. This will cause G1 to allocate an EDEN region. 94 // See JDK-8245925 95 Object o = new Object(); 96 System.out.println("cleaning " + i); 97 } 98 } 99 }