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https://issues.apache.org/jira/browse/HDFS-7435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14339390#comment-14339390
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Charles Lamb commented on HDFS-7435:
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bq. I mildly disagree will overly verbose message for
UnsupportedOperationExceptions since the JDK rarely uses message and the class
& method is in the stack trace.
Yeah, I figured there was a reason for not having a message in the UOE, so it
won't cause me any heartburn if you don't put them in.
bq. I think the whole fragmented over-the-write buffer implementation is over
engineered.
Oh, I kind of liked it.
I'll try to take a look at the new patch soon. Thanks for the reply.
> PB encoding of block reports is very inefficient
> ------------------------------------------------
>
> Key: HDFS-7435
> URL: https://issues.apache.org/jira/browse/HDFS-7435
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode, namenode
> Affects Versions: 2.0.0-alpha, 3.0.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Priority: Critical
> Attachments: HDFS-7435.000.patch, HDFS-7435.001.patch,
> HDFS-7435.002.patch, HDFS-7435.patch, HDFS-7435.patch, HDFS-7435.patch
>
>
> Block reports are encoded as a PB repeating long. Repeating fields use an
> {{ArrayList}} with default capacity of 10. A block report containing tens or
> hundreds of thousand of longs (3 for each replica) is extremely expensive
> since the {{ArrayList}} must realloc many times. Also, decoding repeating
> fields will box the primitive longs which must then be unboxed.
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