[MAPREDUCE-2124] Add job counters for measuring time spent in three different phases in reducers

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 0.22.0
• Component/s: jobtracker
• Assignee: Scott Chen
• Reporter: Scott Chen
• Created: 11/Oct/10 18:03
• Updated: 15/Sep/11 05:34

Description

We currently have SLOTS_MILLIS_REDUCES which measures the total slot time of reducer.
It will be useful if we have

SLOTS_MILLIS_REDUCES_COPY
SLOTS_MILLIS_REDUCES_SORT
SLOTS_MILLIS_REDUCES_REDUCE

which measures three different phases of a reducer.
This will help us identify the bottleneck of the reducers.