[MAPREDUCE-1247] Send out-of-band heartbeat to avoid fake lost tasktracker

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Assignee: ZhuGuanyin
• Reporter: ZhuGuanyin
• Created: 30/Nov/09 07:14
• Updated: 29/Jul/14 20:54
• Resolved: 29/Jul/14 20:54

Description

Currently the TaskTracker report task status to jobtracker through heartbeat, sometimes if the tasktracker lock the tasktracker to do some cleanup job, like remove task temp data on disk, the heartbeat thread would hang for a long time while waiting for the lock, so the jobtracker just thought it had lost and would reschedule all its finished maps or un finished reduce on other tasktrackers, we call it "fake lost tasktracker", some times it doesn't acceptable especially when we run some large jobs. So We introduce a out-of-band heartbeat mechanism to send an out-of-band heartbeat in that case.

Issue Links

• relates to: MAPREDUCE-1662 TaskRunner.prepare() and close() can be removed