test/hotspot/jtreg/runtime/cds/appcds/javaldr/GCDuringDumpTransformer.java

*** 1,7 ****
  /*
!  * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2017, 2020, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 23,53 ****
   */
  
  import java.lang.instrument.ClassFileTransformer;
  import java.lang.instrument.Instrumentation;
  import java.lang.instrument.IllegalClassFormatException;
  import java.security.ProtectionDomain;
  
  public class GCDuringDumpTransformer implements ClassFileTransformer {
      public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,
                              ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {
          try {
              makeGarbage();
          } catch (Throwable t) {
              t.printStackTrace();
              try {
                  Thread.sleep(200); // let GC to have a chance to run
              } catch (Throwable t2) {}
          }
  
          return null;
      }
  
      private static Instrumentation savedInstrumentation;
  
      public static void premain(String agentArguments, Instrumentation instrumentation) {
!         System.out.println("ClassFileTransformer.premain() is called");
          instrumentation.addTransformer(new GCDuringDumpTransformer(), /*canRetransform=*/true);
          savedInstrumentation = instrumentation;
      }
  
      public static Instrumentation getInstrumentation() {
--- 23,75 ----
   */
  
  import java.lang.instrument.ClassFileTransformer;
  import java.lang.instrument.Instrumentation;
  import java.lang.instrument.IllegalClassFormatException;
+ import java.lang.ref.Cleaner;
  import java.security.ProtectionDomain;
  
  public class GCDuringDumpTransformer implements ClassFileTransformer {
+     static boolean TEST_WITH_CLEANER = Boolean.getBoolean("test.with.cleaner");
+     static Cleaner cleaner;
+     static Thread thread;
+     static Object garbage;
+ 
+     static {
+         if (TEST_WITH_CLEANER) {
+             cleaner = Cleaner.create();
+             garbage = new Object();
+             cleaner.register(garbage, new MyCleaner());
+             System.out.println("Registered cleaner");
+         }
+     }
+ 
      public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,
                              ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {
+         if (TEST_WITH_CLEANER) {
+             if (name.equals("Hello")) {
+                 garbage = null;
+                 System.out.println("Unreferenced GCDuringDumpTransformer.garbage");
+             }
+         } else {
              try {
                  makeGarbage();
              } catch (Throwable t) {
                  t.printStackTrace();
                  try {
                      Thread.sleep(200); // let GC to have a chance to run
                  } catch (Throwable t2) {}
              }
+         }
  
          return null;
      }
  
      private static Instrumentation savedInstrumentation;
  
      public static void premain(String agentArguments, Instrumentation instrumentation) {
!         System.out.println("ClassFileTransformer.premain() is called: TEST_WITH_CLEANER = " + TEST_WITH_CLEANER);
          instrumentation.addTransformer(new GCDuringDumpTransformer(), /*canRetransform=*/true);
          savedInstrumentation = instrumentation;
      }
  
      public static Instrumentation getInstrumentation() {
*** 61,66 ****
--- 83,99 ----
      public static void makeGarbage() {
          for (int x=0; x<10; x++) {
              Object[] a = new Object[10000];
          }
      }
+ 
+     static class MyCleaner implements Runnable {
+         static int count = 0;
+         int i = count++;
+         public void run() {
+             // Allocate something. This will cause G1 to allocate an EDEN region.
+             // See JDK-8245925
+             Object o = new Object();
+             System.out.println("cleaning " + i);
+         }
+     }
  }