I am running terasort on 10^12 bytes on a 512 node hadoop cluster. There is something funny about the timings, that I am unable to explain. Probably something trivial, but not visible to my naked eye !
Here are the details - I am using CDH3B3 The job started at 14:47 on 12/10/2010 10/12/10 14:57:18 INFO mapred.JobClient: Running job: job_201012101121_0010 I am looking at the taskTracker log for this job Here are the 4 relevant lines Task TASKID="task_201012101121_0010_m_000087" TASK_TYPE="MAP" START_TIME="1292021852907" SPLITS="/default-rack/hadoop-376,/default-rack/hadoop-444,/default-rack/hadoop-264" . MapAttempt TASK_TYPE="MAP" TASKID="task_201012101121_0010_m_000087" TASK_ATTEMPT_ID="attempt_201012101121_0010_m_000087_0" START_TIME="1291891739732" TRACKER_NAME="tracker_hadoop-444:localhost\.localdomain/127\.0\.0\.1:51062" HTTP_PORT="50060" . MapAttempt TASK_TYPE="MAP" TASKID="task_201012101121_0010_m_000087" TASK_ATTEMPT_ID="attempt_201012101121_0010_m_000087_0" TASK_STATUS="SUCCESS" FINISH_TIME="1291891849493" HOSTNAME="/default-rack/hadoop-444" STATE_STRING="" COUNTERS="{(Fil.... Task TASKID="task_201012101121_0010_m_000087" TASK_TYPE="MAP" TASK_STATUS="SUCCESS" FINISH_TIME="1292021964098" COUNTERS="{(FileSystemCounters)(FileSystemCounters)[(FILE_BYTES_READ)(FILE_BYTES_READ)(97220263)][(HDFS_BYTES_READ)(HDFS_BYTES_READ)(105263208)][(FILE_BYTES_WRITTEN)(FILE_BYTES_WRITTEN)(39496455)]}{(org\.apache\.hadoop\.mapred\.Task$Counter)(Map-Reduce Framework)[(COMBINE_OUTPUT_RECORDS)(Combine output records)(0)][(MAP_INPUT_RECORDS)(Map input records)(1052631)][(SPILLED_RECORDS)(Spilled Records)(2105262)][(MAP_OUTPUT_BYTES)(Map output byte.... Here are the four time stamps logged and the human readable format Task Start 1292021852907 - Fri Dec 10 14:57:32 PST 2010 MapAttempt Start - 1291891739732 - Thu Dec 09 02:48:59 PST 2010 MapAttempt End 1291891849493 - Thu Dec 09 02:50:49 PST 2010 Task End 1292021964098 - Fri Dec 10 14:59:24 PST 2010 The clocks on hadoop-1 (TT) and Hadoop-444 ( the node on which this task ran) are off by a few seconds. ( about 7) Any reason why the Task Timings and the MapAttempt Timings are so off? Raj P.S: Apologize for the long post and posting to multiple locations.