解读：计数器Counter

http://www.cnblogs.com/codeOfLife/p/5521356.html 这个讲的更详细
17/05/23 17:18:53 INFO mapreduce.Job: Counters: 49 #  6类（）49个计数器（亲自数了一遍）。
    File System Counters
        FILE: Number of bytes read=12222
        FILE: Number of bytes written=239539
        FILE: Number of read operations=0
        FILE: Number of large read operations=0
        FILE: Number of write operations=0
        HDFS: Number of bytes read=11316
        HDFS: Number of bytes written=1892
        HDFS: Number of read operations=8
        HDFS: Number of large read operations=0
        HDFS: Number of write operations=2
    Job Counters 
        Launched map tasks=1
        Launched reduce tasks=1
        Other local map tasks=1
        Total time spent by all maps in occupied slots (ms)=21775
        Total time spent by all reduces in occupied slots (ms)=16960
        Total time spent by all map tasks (ms)=21775
        Total time spent by all reduce tasks (ms)=16960
        Total vcore-milliseconds taken by all map tasks=21775
        Total vcore-milliseconds taken by all reduce tasks=16960
        Total megabyte-milliseconds taken by all map tasks=22297600
        Total megabyte-milliseconds taken by all reduce tasks=17367040
    Map-Reduce Framework
        Map input records=108
        Map output records=216
        Map output bytes=11784
        Map output materialized bytes=12222
        Input split bytes=279
        Combine input records=0
        Combine output records=0
        Reduce input groups=36
        Reduce shuffle bytes=12222
        Reduce input records=216
        Reduce output records=36
        Spilled Records=432
        Shuffled Maps =1
        Failed Shuffles=0
        Merged Map outputs=1
        GC time elapsed (ms)=232
        CPU time spent (ms)=2180
        Physical memory (bytes) snapshot=273268736
        Virtual memory (bytes) snapshot=4118401024
        Total committed heap usage (bytes)=137498624
    Shuffle Errors
        BAD_ID=0
        CONNECTION=0
        IO_ERROR=0
        WRONG_LENGTH=0
        WRONG_MAP=0
        WRONG_REDUCE=0
    File Input Format Counters 
        Bytes Read=0
    File Output Format Counters 
        Bytes Written=1892