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https://issues.apache.org/jira/browse/MAPREDUCE-60?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Boudnik updated MAPREDUCE-60:
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Tags: surelogic
> Nested class TaskTracker.TaskInProgress needs additional synchronization
> ------------------------------------------------------------------------
>
> Key: MAPREDUCE-60
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-60
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Environment: All Java platforms
> Reporter: Aaron Greenhouse
> Attachments: HADOOP-3553.patch
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> The nested class TaskTracker.TaskInProgress needs additional synchronization
> to work properly with the Java Memory Model. Presumably this class is
> accessed by more than one thread, because it already contains
> synchronization. However, it needs additional synchronization, especially to
> protect access to the long fields lastProgressReport and taskTimeOut. Long
> fields are not guaranteed to be read/written atomically, so not only do you
> risk reading stale values, but you risk reading corrupted values.
> The field wasKilled also needs synchronization, as it is polled from within
> the TaskTracker class.
> I suggest the following improvements to the class
> - Make the fields task and taskStatus final. They are used this way already.
> Making them final clarifies there behavior in a current environment.
> - Add the synchronized modifier to the methods getLastProgressReport() and
> getTaskTimeout().
> - Make the field wasKilled private and add a new public synchronized
> wasKilled() getter method. Replace the use of the field with this method in
> TaskTracker.
> - Add a comment to localizeTask() indicating that the caller must be
> synchronized on this.
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