1 /*
   2  * Copyright (c) 2012, 2013, 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 /*
  26  * @test
  27  * @bug 7190310
  28  * @summary Inlining WeakReference.get(), and hoisting $referent may lead to non-terminating loops
  29  * @run main/othervm/timeout=600 -Xbatch Test7190310
  30  */
  31 
  32 /*
  33  * Note bug exhibits as infinite loop, timeout is helpful.
  34  * It should normally finish pretty quickly, but on some especially slow machines
  35  * it may not.  The companion _unsafe test lacks a timeout, but that is okay.
  36  */
  37 
  38 import java.lang.ref.*;
  39 
  40 public class Test7190310 {
  41   private static Object str = new Object() {
  42     public String toString() {
  43       return "The Object";
  44     }
  45 
  46     protected void finalize() throws Throwable {
  47       System.out.println("The Object is being finalized");
  48       super.finalize();
  49     }
  50   };
  51   private final static ReferenceQueue<Object> rq =
  52       new ReferenceQueue<Object>();
  53   private final static WeakReference<Object> wr =
  54       new WeakReference<Object>(str, rq);
  55 
  56   public static void main(String[] args)
  57       throws InterruptedException {
  58     Thread reader = new Thread() {
  59       public void run() {
  60         while (wr.get() != null) {
  61         }
  62         System.out.println("wr.get() returned null");
  63       }
  64     };
  65 
  66     Thread queueReader = new Thread() {
  67       public void run() {
  68         try {
  69           Reference<? extends Object> ref = rq.remove();
  70           System.out.println(ref);
  71           System.out.println("queueReader returned, ref==wr is "
  72               + (ref == wr));
  73         } catch (InterruptedException e) {
  74           System.err.println("Sleep interrupted - exiting");
  75         }
  76       }
  77     };
  78 
  79     reader.start();
  80     queueReader.start();
  81 
  82     Thread.sleep(1000);
  83     str = null;
  84     System.gc();
  85   }
  86 }
  87