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https://issues.apache.org/jira/browse/HDFS-8088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14486519#comment-14486519
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Colin Patrick McCabe commented on HDFS-8088:
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* Shorten the method names we're tracing. {{ClientProtocol#create}} instead of
{{org.apache.hadoop.hdfs.protocol.ClientProtocol.create}}, etc.
* Don't create trace spans for {{DFSInputStream#read(final byte buf[], int off,
int len)}} and {{int read(final ByteBuffer buf)}}. Note that we still create
trace spans inside the block readers, when refilling the block reader buffers.
* RemoteBlockReader2.java: include the block ID as a key/value annotation, not
in the name of the trace span itself.
* TestTracing.java: explain which trace spans we couldn't find, if we can't
find some trace spans we are looking for.
> Reduce the number of HTrace spans generated by HDFS reads
> ---------------------------------------------------------
>
> Key: HDFS-8088
> URL: https://issues.apache.org/jira/browse/HDFS-8088
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-8088.001.patch
>
>
> HDFS generates too many trace spans on read right now. Every call to read()
> we make generates its own span, which is not very practical for things like
> HBase or Accumulo that do many such reads as part of a single operation.
> Instead of tracing every call to read(), we should only trace the cases where
> we refill the buffer inside a BlockReader.
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