--- jsr166/src/jsr166e/ForkJoinTask.java	2013/07/21 06:32:28	1.14
+++ jsr166/src/jsr166e/ForkJoinTask.java	2013/09/20 10:52:13	1.16
@@ -411,11 +411,13 @@ public abstract class ForkJoinTask<V> im
         final Throwable ex;
         ExceptionNode next;
         final long thrower;  // use id not ref to avoid weak cycles
+        final int hashCode;  // store task hashCode before weak ref disappears
         ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
             super(task, exceptionTableRefQueue);
             this.ex = ex;
             this.next = next;
             this.thrower = Thread.currentThread().getId();
+            this.hashCode = System.identityHashCode(task);
         }
     }
 
@@ -574,12 +576,15 @@ public abstract class ForkJoinTask<V> im
     /**
      * Poll stale refs and remove them. Call only while holding lock.
      */
+    /**
+     * Poll stale refs and remove them. Call only while holding lock.
+     */
     private static void expungeStaleExceptions() {
         for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
             if (x instanceof ExceptionNode) {
-                ForkJoinTask<?> key = ((ExceptionNode)x).get();
+                int hashCode = ((ExceptionNode)x).hashCode;
                 ExceptionNode[] t = exceptionTable;
-                int i = System.identityHashCode(key) & (t.length - 1);
+                int i = hashCode & (t.length - 1);
                 ExceptionNode e = t[i];
                 ExceptionNode pred = null;
                 while (e != null) {
@@ -1473,6 +1478,8 @@ public abstract class ForkJoinTask<V> im
     /**
      * Saves this task to a stream (that is, serializes it).
      *
+     * @param s the stream
+     * @throws java.io.IOException if an I/O error occurs
      * @serialData the current run status and the exception thrown
      * during execution, or {@code null} if none
      */
@@ -1484,6 +1491,10 @@ public abstract class ForkJoinTask<V> im
 
     /**
      * Reconstitutes this task from a stream (that is, deserializes it).
+     * @param s the stream
+     * @throws ClassNotFoundException if the class of a serialized object
+     *         could not be found
+     * @throws java.io.IOException if an I/O error occurs
      */
     private void readObject(java.io.ObjectInputStream s)
         throws java.io.IOException, ClassNotFoundException {