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https://issues.apache.org/jira/browse/HDFS-7055?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14145221#comment-14145221
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stack commented on HDFS-7055:
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bq. One thing to keep in mind here is that if you call Trace.startSpan with
Sampler.NEVER, and there is an existing thread trace span, a subspan will
always be created.
Thanks for mentioning this up front... first thing I stumbled on looking in
code. Its a little confusing but having a comment to explain NEVER in every
span open, it'll get annoying fast.
Nit: This exception, if it possible to ask trace for the list of options,
should list the possible options (I can see folks typing in sampler with wrong
case or missing a piece... listing possible options will allow them quickly see
what they have done wrong):
+ throw new RuntimeException("Can't create sampler " + samplerStr);
Nit: Should we have a convention naming spans [~cmccabe]? For example, method
name followed by arg types all in camel case?
+ dfsClient.getTraceScope("byteBufferRead", src);
... would become readByteBuffer and +
dfsClient.getTraceScope("byteArrayRead", src); would be readByteArrayIntInt?
Patch looks great to me. You gotten any spans out of it? I can try it if you'd
like, no problem.
> Add tracing to DFSInputStream
> -----------------------------
>
> Key: HDFS-7055
> URL: https://issues.apache.org/jira/browse/HDFS-7055
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, namenode
> Affects Versions: 2.6.0
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-7055.002.patch
>
>
> Add tracing to DFSInputStream.
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