--- jsr166/src/test/tck/RecursiveActionTest.java	2011/06/24 18:49:56	1.33
+++ jsr166/src/test/tck/RecursiveActionTest.java	2011/06/27 02:47:32	1.37
@@ -12,9 +12,11 @@ import java.util.concurrent.ForkJoinPool
 import java.util.concurrent.ForkJoinTask;
 import java.util.concurrent.ForkJoinWorkerThread;
 import java.util.concurrent.RecursiveAction;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import static java.util.concurrent.TimeUnit.SECONDS;
+import java.util.Arrays;
 import java.util.HashSet;
 
 public class RecursiveActionTest extends JSR166TestCase {
@@ -1195,4 +1197,47 @@ public class RecursiveActionTest extends
         testInvokeOnPool(asyncSingletonPool(), a);
     }
 
+    /** Demo from RecursiveAction javadoc */
+    static class SortTask extends RecursiveAction {
+        final long[] array; final int lo, hi;
+        SortTask(long[] array, int lo, int hi) {
+            this.array = array; this.lo = lo; this.hi = hi;
+        }
+        SortTask(long[] array) { this(array, 0, array.length); }
+        protected void compute() {
+            if (hi - lo < THRESHOLD)
+                sortSequentially(lo, hi);
+            else {
+                int mid = (lo + hi) >>> 1;
+                invokeAll(new SortTask(array, lo, mid),
+                          new SortTask(array, mid, hi));
+                merge(lo, mid, hi);
+            }
+        }
+        // implementation details follow:
+        final static int THRESHOLD = 100;
+        void sortSequentially(int lo, int hi) {
+            Arrays.sort(array, lo, hi);
+        }
+        void merge(int lo, int mid, int hi) {
+            long[] buf = Arrays.copyOfRange(array, lo, mid);
+            for (int i = 0, j = lo, k = mid; i < buf.length; j++)
+                array[j] = (k == hi || buf[i] < array[k]) ?
+                    buf[i++] : array[k++];
+        }
+    }
+
+    /**
+     * SortTask demo works as advertised
+     */
+    public void testSortTaskDemo() {
+        ThreadLocalRandom rnd = ThreadLocalRandom.current();
+        long[] array = new long[1007];
+        for (int i = 0; i < array.length; i++)
+            array[i] = rnd.nextLong();
+        long[] arrayClone = array.clone();
+        testInvokeOnPool(mainPool(), new SortTask(array));
+        Arrays.sort(arrayClone);
+        assertTrue(Arrays.equals(array, arrayClone));
+    }
 }