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https://issues.apache.org/jira/browse/HDFS-14179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16747082#comment-16747082
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Ayush Saxena commented on HDFS-14179:
-------------------------------------
Thanx Everyone for the work here.
I am having a minor doubt on this, Whether this will not impact the performance
of read process.This seems to be adding some extra processing overhead during
the time of packet read for the LOG purpose. Though the overhead may seem quite
minor but this is at packet level,at block level it shall magnify,at file level
even more and so on.
If I am not missing on or getting into some wrong zone.This would effect the
read performance and read being an elementary operation I am not sure whether
we can afford it .Even can't say whether this log will bring that much value to
us as compared to the cost it would take.
Pls correct me if I have misunderstood something on this context. :)
> BlockReaderRemote#readNextPacket() should log the waiting time for packet
> read.
> -------------------------------------------------------------------------------
>
> Key: HDFS-14179
> URL: https://issues.apache.org/jira/browse/HDFS-14179
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 3.0.0
> Reporter: Surendra Singh Lilhore
> Assignee: Shubham Dewan
> Priority: Major
> Labels: newbie
> Attachments: HDFS-14179.001.patch, HDFS-14179.002.patch,
> HDFS-14179.003.patch
>
>
> Sometime read is reported very slow due to disk or some other reason.
> {{BlockReaderRemote#readNextPacket()}} should print the datanode IP and
> waiting time in trace log.
> {code:java}
> //Read packet headers.
> packetReceiver.receiveNextPacket(in);
> PacketHeader curHeader = packetReceiver.getHeader();
> curDataSlice = packetReceiver.getDataSlice();
> assert curDataSlice.capacity() == curHeader.getDataLen();
> LOG.trace("DFSClient readNextPacket got header {}", curHeader);{code}
>
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