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https://issues.apache.org/jira/browse/HDFS-350?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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dhruba borthakur reassigned HDFS-350:
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Assignee: dhruba borthakur
> DFSClient more robust if the namenode is busy doing GC
> ------------------------------------------------------
>
> Key: HDFS-350
> URL: https://issues.apache.org/jira/browse/HDFS-350
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> In the current code, if the client (writer) encounters an RPC error while
> fetching a new block id from the namenode, it does not retry. It throws an
> exception to the application. This becomes especially bad if the namenode is
> in the middle of a GC and does not respond in time. The reason the client
> throws an exception is because it does not know whether the namenode
> successfully allocated a block for this file.
> One possible enhancement would be to make the client retry the addBlock RPC
> if needed. The client can send the block list that it currently has. The
> namenode can match the block list send by the client with what it has in its
> own metadata and then send back a new blockid (or a previously allocated
> blockid that the client had not yet received because the earlier RPC
> timedout). This will make the client more robust!
> This works even when we support Appends because the namenode will *always*
> verify that the client has the lease for the file in question.
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