问题
If I output some message thru stdout (System.out in Java) and stderr (System.err in Java) in Mapper and Reducer, where can I see them in task tracker node? I guess the directory location is configurable thru some parameter as well?
回答1:
This might depend on which distribution you are using but with our cdh3 setup, we can find them under /usr/lib/hadoop-0.20/logs/userlogs// on the node where the task ran. For example, stderr would be under:
/usr/lib/hadoop-0.20/logs/userlogs/job_201207010432_5284/attempt_201207010432_5284_m_000214_0/stderr
If you have access to the job tracker UI for your cluster, you can also access them through there (which is what I typically do).
来源：https://stackoverflow.com/questions/11596801/mapreduce-log-file-locations-for-stdout-and-std-err