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https://issues.apache.org/jira/browse/HDFS-5274?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Masatake Iwasaki updated HDFS-5274:
-----------------------------------
Attachment: HDFS-5274-7.patch
I am attaching the patch rebased and updated based on review comments.
bq. Any reason we take config on construction and in init for SpanReceiverHost?
I removed conf from constructor argument.
bq. SpanReceiverHost is on only when trace is enabled, right? If so, say so in
class comment.
SpanReceiverHost is always on, though it do nothing if no SpanReceiver is
configured. I added a line in class comment.
bq. Has to be a shutdown hook? ShutdownHookManager.get().addShutdownHook ? This
is fine unless we envision someone having to override it which I suppose should
never happen for an optionally enabled, rare, trace function?
Overriding SpanReceiverHost is not necessary, though there could be someone who
implement SpanReceiver. I think it is useful to wait for receivers to process
all the tracing data on crash scenario.
bq. HTraceConfiguration is for testing only? Should be @visiblefortesting only
or a comment at least?
HTraceConfiguration is used by SpanReceiver implementation, not for testing
only.
bq. Should there be defines for a few of these? "DFSInputStream.close" seems
fine... only used once DFSInputStream.read?
I think it is fine not to define "DFSInputStream.read" now.
----
There are some fixes in addition to above such as,
* removed timing dependency from TestTracing.
* added guard by Trace.isTracing() around startSpan() in DFSInputStream,
FsShell and WritableRpcEngine.
* removed SpanReceiverHost from FsShell and DFSClient. I will add options or
config properties to turn on tracing from shell later on another JIRA issue.
> Add Tracing to HDFS
> -------------------
>
> Key: HDFS-5274
> URL: https://issues.apache.org/jira/browse/HDFS-5274
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: datanode, namenode
> Affects Versions: 2.1.1-beta
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Attachments: HDFS-5274-0.patch, HDFS-5274-1.patch, HDFS-5274-2.patch,
> HDFS-5274-3.patch, HDFS-5274-4.patch, HDFS-5274-5.patch, HDFS-5274-6.patch,
> HDFS-5274-7.patch, Zipkin Trace a06e941b0172ec73.png, Zipkin Trace
> d0f0d66b8a258a69.png
>
>
> Since Google's Dapper paper has shown the benefits of tracing for a large
> distributed system, it seems like a good time to add tracing to HDFS. HBase
> has added tracing using HTrace. I propose that the same can be done within
> HDFS.
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