[HADOOP-3140] JobTracker should not try to promote a (map) task if it does not write to DFS at all

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.17.0
• Hadoop Flags: Reviewed
• Release Note: Tasks that don't generate any output are not inserted in the commit queue of the JobTracker. They are marked as SUCCESSFUL by the TaskTracker and the JobTracker updates their state short-circuiting the commit queue.
• Assignee: Amar Kamat
• Reporter: Runping Qi
• Created: 31/Mar/08 21:22
• Updated: 08/Jul/09 16:52
• Resolved: 04/Apr/08 16:34

Description

In most cases, map tasks do not write to dfs.
Thus, when they complete, they should not be put into commit_pending queue at all.
This will improve the task promotion significantly.