MapReduce性能优化_1. 性能测量

<span style="color:#ff0000;">$ hadoop job -history outputHadoop job: job_201112081615_0181</span>=====================================Job tracker host name: localhostSubmitted At: 23-Dec-2011 08:55:22Launched At: 23-Dec-2011 08:55:22 (0sec)Finished At: 23-Dec-2011 08:55:37 (15sec)Status: SUCCESSCounters: |Group Name |Counter name |Map Value |Reduce Value|Total |-------------------------------------------------------------------|FileSystem |FILE_BYTES_READ |0 |961,831 |961,831|FileSystem |HDFS_BYTES_READ |696,068 |0 |696,068|FileSystem |FILE_BYTES_WRITTEN |1,071,837 |1,071,519 |2,143,356|FileSystem |HDFS_BYTES_WRITTEN |0 |784,221 |784,221... Analysis=========Time taken by best performing map task 2secAverage time taken by map tasks: 2secWorse performing map tasks:TaskId Timetakentask_201112081615_0181_m_000001 2sec...<span style="color:#ff0000;">$ hadoop job -history