Review Board 1.7.22

HBASE-6004 Adding more logging to help debugging MR job

Review Request #5131 - Created May 15, 2012 and submitted

Jimmy Xiang
Added some logging for MR debugging in case scanner times out.  The logging is disabled by default.
It will be helpful to know how much time spent in the scanner and, how much in the mapper task.
In case scanner issue, it is helpful to know the region server id, last successful rows and so on.

Review request changed
Updated (May 16, 2012, 2:56 a.m.)