It runs very well at the first several times, but when run it again, the
hadoop system become pretty much slow and show the following errors during
the runnig process(map 100% reduce: 22%) though it finally succeed.
Info mapred.JobClient: Task Id : attempt_xxx_0030_m_002_0, Status:
FAILED: many fetch_failures
When I run it again, it become OK until same failures after another several
time run. Any potential reasons? How can I probe this issue? Thx.
