Index: lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/tasks/TaskSequence.java
===================================================================
--- lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/tasks/TaskSequence.java	(revision 1367933)
+++ lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/tasks/TaskSequence.java	(working copy)
@@ -331,7 +331,9 @@
     // Forwards top request to children
     if (runningParallelTasks != null) {
       for(ParallelTask t : runningParallelTasks) {
-        t.task.stopNow();
+        if (t != null) {
+          t.task.stopNow();
+        }
       }
     }
   }
@@ -355,6 +357,12 @@
     // run threads
     startThreads(t);
 
+    if (stopNow) {
+      for (ParallelTask task : t) {
+        task.task.stopNow();
+      }
+    }
+
     // wait for all threads to complete
     int count = 0;
     for (int i = 0; i < t.length; i++) {