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https://issues.apache.org/jira/browse/HDFS-14179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16747429#comment-16747429
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Surendra Singh Lilhore commented on HDFS-14179:
-----------------------------------------------
Thanks [~shubham.dewan] for the patch.
{code:java}
+ iothreshold = conf.getLong(
+ HdfsClientConfigKeys.DFS_CLIENT_SLOW_IO_WARNING_THRESHOLD_KEY,
+
HdfsClientConfigKeys.DFS_CLIENT_SLOW_IO_WARNING_THRESHOLD_DEFAULT);{code}
Get conf value only one time, so add it in constructor.
{quote}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.
{quote}
I don't think calculating time duration for packet read is overhead.
[~arpitagarwal], [~brahmareddy] What is your opinion ?
> 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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