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https://issues.apache.org/jira/browse/HADOOP-1446?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12500873
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David Bowen commented on HADOOP-1446:
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The TaskTracker fields mapTotal and reduceTotal now need to be declared
volatile, since they are being accessed from the Metrics thread.
Also, completeTask is wrong. Actually, it was wrong before your changes (my
bad). Now, as soon as one task has been completed, it will report one task
being completed every blurb period regardless of the actual number. The
suggested fix is to add a numCompletedTasks field to TaskTrackerMetrics, and
make completeTask simply increment that field. Then doUpdates should call
incrMetric(numCompletedTasks), and afterwards set numCompletedTasks=0.
In general, all the metrics in a MetricsRecord should be updated in the same
place in the code, and update() should be called immediately afterwards.
> Metrics from the TaskTracker are updated only when map/reduce tasks
> start/end/fail
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-1446
> URL: https://issues.apache.org/jira/browse/HADOOP-1446
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.12.3
> Reporter: Devaraj Das
> Assignee: Devaraj Das
> Fix For: 0.14.0
>
> Attachments: 1446.patch
>
>
> Metrics reporting from the TaskTracker for the maps_running and
> reduces_running metrics are done only when a task is starting up or finishing
> up. This is wrong and the metrics reporting should be done periodically
> during the life of the TaskTracker just as it is done for the JobTracker case.
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