[MAPREDUCE-6251] JobClient needs additional retries at a higher level to address not-immediately-consistent dfs corner cases

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.8.0, 2.7.1, 3.0.0-alpha1
• Component/s: jobhistoryserver, mrv2
• Labels: BB2015-05-TBR
• Target Version/s: 2.8.0
• Hadoop Flags: Reviewed
• Assignee: Craig Welch
• Reporter: Craig Welch
• Created: 10/Feb/15 21:47
• Updated: 09/Jun/18 05:13
• Resolved: 12/May/15 19:16

Description

The JobClient is used to get job status information for running and completed jobs. Final state and history for a job is communicated from the application master to the job history server via a distributed file system - where the history is uploaded by the application master to the dfs and then scanned/loaded by the jobhistory server. While HDFS has strong consistency guarantees not all Hadoop DFS's do. When used in conjunction with a distributed file system which does not have this guarantee there will be cases where the history server may not see an uploaded file, resulting in the dreaded "no such job" and a null value for the RunningJob in the client.

Issue Links

• is related to: MAPREDUCE-7101 Add config parameter to allow JHS to alway scan user dir irrespective of modTime