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https://issues.apache.org/jira/browse/MAPREDUCE-5026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13592076#comment-13592076
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Tian Hong Wang commented on MAPREDUCE-5026:
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Hi sam
Why you fetch the freeDiskSpace,cpu and memory value at the different speed
rate?
> For shortening the time of TaskTracker heartbeat, decouple the statics
> collection operations
> --------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5026
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5026
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: performance, tasktracker
> Affects Versions: 1.1.1
> Reporter: sam liu
> Labels: patch
> Fix For: 1.1.1
>
> Attachments: HDFS-4527.patch
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> In each heartbeat of TaskTracker, it will calculate some system statics, like
> the free disk space, available virtual/physical memory, cpu usage, etc.
> However, it's not necessary to calculate all the statics in every heartbeat,
> and this will consume many system resource and impace the performance of
> TaskTracker heartbeat. Furthermore, the characteristics of system
> properties(disk, memory, cpu) are different and it's better to collect their
> statics in different intervals.
> To reduce the latency of TaskTracker heartbeat, one solution is to decouple
> all the system statics collection operations from it, and issue separate
> threads to do the statics collection works when the TaskTracker starts. The
> threads could be three: the first one is to collect cpu related statics in a
> short interval; the second one is to collect memory related statics in a
> normal interval; the third one is to collect disk related statics in a long
> interval. And all the interval could be customized by the parameter
> "mapred.stats.collection.interval" in the mapred-site.xml. At last, the
> heartbeat could get values of system statics from the memory directly.
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