[MAPREDUCE-108] Blacklisted hosts may not be able to serve map outputs

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Incomplete
• Assignee: Amar Kamat
• Reporter: Runping Qi
• Created: 08/Nov/07 23:26
• Updated: 17/Jul/14 18:23
• Resolved: 17/Jul/14 18:23

Description

After a node fails 4 mappers (tasks), it is added to blacklist thus it will no longer accept tasks.
But, it will continue serve the map outputs of any mappers that ran successfully there.
However, the node may not be able serve the map outputs either.
This will cause the reducers to mark the corresponding map outputs as from slow hosts,
but continue to try to get the map outputs from that node.
This may lead to waiting forever.

Issue Links

• relates to: HADOOP-4305 repeatedly blacklisted tasktrackers should get declared dead