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https://issues.apache.org/jira/browse/HADOOP-1501?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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dhruba borthakur updated HADOOP-1501:
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Assignee: dhruba borthakur
Status: Patch Available (was: Open)
Thanks for the review. I have not yet changed the 90-100% variablity of the
periodicity of the block reports. I would like to keep that variability because
it provides us with another randomization factor so that all block reports do
not arrive at the namenode at around the same time.
> Block reports from all datanodes arrive at the namenode within a small band
> of time
> -----------------------------------------------------------------------------------
>
> Key: HADOOP-1501
> URL: https://issues.apache.org/jira/browse/HADOOP-1501
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: randomBlockReportInterval.patch
>
>
> I have a 2000 node cluster and the block report interval is set to 1 hour.
> Most block report arrive within a few minutes of one another. For example, I
> have seen block reports from all 2000 nodes arrive within 5 minutes of one
> another. This causes CPU overload on the namenode, causing dropped calls in
> Call queue.
> My proposal is to make the datanode send a block report as soon as the
> datanode starts. Then, it waits for a random time between 0 to 1 hour (the
> configured value) before sending the nect block report. From then on, block
> reports from that datanode are sent once every 1 hour (the configured value).
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