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Posted to common-dev@hadoop.apache.org by "Sanjay Dahiya (JIRA)" <ji...@apache.org> on 2006/09/25 12:27:55 UTC
[jira] Updated: (HADOOP-547) ReduceTaskRunner can miss sending
hearbeats if no map output copy finishes within "mapred.task.timeout"
[ http://issues.apache.org/jira/browse/HADOOP-547?page=all ]
Sanjay Dahiya updated HADOOP-547:
---------------------------------
Attachment: Hadoop-547.patch
Here is a patch for review -
It makes sure that reduce task, sends a heartbeat/progress when none of copy tasks finishes with in "mapred.task.timeout". It replaces the unconditional wait with a conditional wait with a timeout of (mapred.task.timeout)/2. (we could make it 3/4th of this timeout as well).
> ReduceTaskRunner can miss sending hearbeats if no map output copy finishes within "mapred.task.timeout"
> -------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-547
> URL: http://issues.apache.org/jira/browse/HADOOP-547
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.6.2
> Reporter: Sanjay Dahiya
> Assigned To: Sanjay Dahiya
> Attachments: Hadoop-547.patch
>
>
> 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.
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