[HADOOP-547] ReduceTaskRunner can miss sending hearbeats if no map output copy finishes within "mapred.task.timeout"

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.6.2
• Fix Version/s: 0.7.0
• Assignee: Sanjay Dahiya
• Reporter: Sanjay Dahiya
• Created: 19/Sep/06 10:55
• Updated: 08/Jul/09 16:51
• Resolved: 25/Sep/06 23:03

Description

In ReduceTaskRunner, main loop sending heartbeats waits on copyResults, which releases only if a copy thread finishes copying. This can cause good reduce tasks which are copying data to fail, if no map task output was copied within "mapred.task.timeout".

ReduceTaskRunner.java:490
try

{ copyResults.wait(); <=========== Calls unconditional wait. }

catch (InterruptedException e) { }

wait() should be with a timeout, possibly taskTimeout/2 after which it should send a hearbeat and go back to wait.