[MAPREDUCE-1829] JobInProgress.findSpeculativeTask should use min() to find the candidate instead of sort()

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.22.0
• Fix Version/s: 0.22.0
• Component/s: jobtracker
• Hadoop Flags: Reviewed
• Release Note: Improved performance of the method JobInProgress.findSpeculativeTask() which is in the critical heartbeat code path.
• Assignee: Scott Chen
• Reporter: Scott Chen
• Created: 01/Jun/10 18:04
• Updated: 12/Dec/11 06:19
• Resolved: 12/Jun/10 09:56

Description

findSpeculativeTask needs only one candidate to speculate so it does not need to sort the whole list. It may looks OK but someone can still submit big jobs with small slow task thresholds. In this case, this sorting becomes expensive.