[MAPREDUCE-513] Prior code fix in Capacity Scheduler prevents speculative execution in jobs

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Assignee: Sreekanth Ramakrishnan
• Reporter: Vivek Ratan
• Created: 05/Jan/09 08:38
• Updated: 29/Jul/09 08:55
• Resolved: 29/Jul/09 08:55

Description

As part of the code fix for HADOOP-4035, the Capacity Scheduler obtains a task from JobInProgress (calling obtainNewMapTask() or obtainNewReduceTask()) only if the number of pending tasks for a job is greater than zero (see the if-block in TaskSchedulingMgr.getTaskFromJob()). So, if a job has no pending tasks and only has running tasks, it will never be given a slot, and will never have a chance to run a speculative task.