Add the following to the mapred-site.xml file:
mapred.child.java.opts : Java opts for the task tracker child processes. The following symbol, if present, will be interpolated: @taskid@ is replaced by current TaskID. Any other occurrences of '@' will go unchanged. For example, to enable verbose gc logging to a file named for the taskid in /tmp and to set the heap maximum to be a gigabyte, pass a 'value' of: -Xmx1024m -verbose:gc -Xloggc:/tmp/@taskid@.gc.
Additional options: -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC
Reference: http://hadoop.apache.org/docs/r1.0.0/mapred-default.html
Analyzing GC logs:
-------------------------
Meaning of the [GC [PSYoungGen: 230400K->19135K(268800K)] line is:
Reference: http://middlewaremagic.com/weblogic/?p=5131
https://www.ibm.com/developerworks/community/groups/service/html/communityview?communityUuid=22d56091-3a7b-4497-b36e-634b51838e11
mapred.child.java.opts : Java opts for the task tracker child processes. The following symbol, if present, will be interpolated: @taskid@ is replaced by current TaskID. Any other occurrences of '@' will go unchanged. For example, to enable verbose gc logging to a file named for the taskid in /tmp and to set the heap maximum to be a gigabyte, pass a 'value' of: -Xmx1024m -verbose:gc -Xloggc:/tmp/@taskid@.gc.
Additional options: -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC
Reference: http://hadoop.apache.org/docs/r1.0.0/mapred-default.html
Analyzing GC logs:
-------------------------
Meaning of the [GC [PSYoungGen: 230400K->19135K(268800K)] line is:
- Around 256MB (268800K) is the Young Generation Size,
- Before Garbage Collection in young generation the heap utilization in Young Generation area was around 255MB (230400K) and
- After garbage collection it reduced up to 18MB (19135K).
Reference: http://middlewaremagic.com/weblogic/?p=5131
https://www.ibm.com/developerworks/community/groups/service/html/communityview?communityUuid=22d56091-3a7b-4497-b36e-634b51838e11
