[MAPREDUCE-1797] The JobTracker lock can be a reader/writer lock

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Component/s: jobtracker
• Assignee: Dhruba Borthakur
• Reporter: Dhruba Borthakur
• Created: 18/May/10 22:07
• Updated: 30/Jul/14 19:36
• Resolved: 30/Jul/14 19:36

Description

The Jobtracker has a global lock and a per-job JobInProgress lock. The aim for the JobInprogress lock is to support the ability to lock a single job's metadata without blocking out the entire JobTracker. However, many code paths acquire the JobTracker lock and then acquire the JobInProgress lock while keeping the JobTracker lock. This somewhat defeats the benefit of having a per-job lock.