[HADOOP-4979] Capacity Scheduler does not always return no task to a TT if a job's memry requirements are not met

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.20.0
• Hadoop Flags: Reviewed
• Assignee: Vivek Ratan
• Reporter: Vivek Ratan
• Created: 05/Jan/09 04:25
• Updated: 08/Jul/09 16:40
• Resolved: 05/Jan/09 11:40

Description

As per HADOOP-4035, the Capacity Scheduler should return no task to a TT if a job's high mem requirements are not met. This doesn't always happen. In the Scheduler's assignTasks() method, if a job's map task does not enough memory to run, the Scheduler looks at reduce tasks, and vice-versa. This can result in a case where a reduce task from another job is returned to the TT (if the high-mem job does not have a reduce task to run, for example), thus starving the high-mem job.