MAPREDUCE-6194. Bubble up final exception in failures during creation of output collectors. Contributed by Varun Saxena.

(cherry picked from commit 298d09c9b583088f364038adcb1edf1eb1c2c196)

hadoop-mapreduce-project/CHANGES.txt

@@ -8,6 +8,9 @@ Release 2.7.0 - UNRELEASED
 
   IMPROVEMENTS
 
+    MAPREDUCE-6194. Bubble up final exception in failures during creation
+    of output collectors (Varun Saxena via harsh)
+
     MAPREDUCE-5420. Remove mapreduce.task.tmp.dir from mapred-default.xml
     (James Carman via harsh)
 

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java

@@ -387,6 +387,7 @@ public class MapTask extends Task {
     Class<?>[] collectorClasses = job.getClasses(
       JobContext.MAP_OUTPUT_COLLECTOR_CLASS_ATTR, MapOutputBuffer.class);
     int remainingCollectors = collectorClasses.length;
+    Exception lastException = null;
     for (Class clazz : collectorClasses) {
       try {
         if (!MapOutputCollector.class.isAssignableFrom(clazz)) {
@@ -406,10 +407,12 @@ public class MapTask extends Task {
         if (--remainingCollectors > 0) {
           msg += " (" + remainingCollectors + " more collector(s) to try)";
         }
+        lastException = e;
         LOG.warn(msg, e);
       }
     }
-    throw new IOException("Unable to initialize any output collector");
+    throw new IOException("Initialization of all the collectors failed. " +
+      "Error in last collector was :" + lastException.getMessage(), lastException);
   }
 
   @SuppressWarnings("unchecked")