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https://issues.apache.org/jira/browse/MAPREDUCE-2349?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vinod Kumar Vavilapalli updated MAPREDUCE-2349:
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Status: Open (was: Patch Available)
Started looking at it, nicely done patch! Few minor comments
- Add the configs to mapred-default.xml as documentation?
- LIST_STATUS_NUM_THREADS_DEFAULT -> DEFAULT_LIST_STATUS_NUM_THREADS
- oldListStatus() -> singleThreadedListStatus()
- Can you add a bit of javadoc to all the new classes and methods in
LocatedFileStatusFetcher? Also to the main LocatedFileStatusFetcher class
itself.
- Synchronization needed for ProcessInitialInputPathResult.addError()?
- Can you group the callable, result and call-back for each type of operation
together in two classes?
- The 'result' variable doesn't need to be a class field of
ProcessInputDirCallable. Similarly the one in ProcessInitialInputPathCallable.
The tests look good!
> speed up list[located]status calls from input formats
> -----------------------------------------------------
>
> Key: MAPREDUCE-2349
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2349
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: task
> Reporter: Joydeep Sen Sarma
> Assignee: Siddharth Seth
> Attachments: MAPREDUCE-2349.1.wip.txt, MAPREDUCE-2349.2.txt,
> MAPREDUCE-2349.3.txt, MAPREDUCE-2349.4.txt
>
>
> when a job has many input paths - listStatus - or the improved
> listLocatedStatus - calls (invoked from the getSplits() method) can take a
> long time. Most of the time is spent waiting for the previous call to
> complete and then dispatching the next call.
> This can be greatly speeded up by dispatching multiple calls at once (via
> executors). If the same filesystem client is used - then the calls are much
> better pipelined (since calls are serialized) and don't impose extra burden
> on the namenode while at the same time greatly reducing the latency to the
> client. In a simple test on non-peak hours, this resulted in the getSplits()
> time reducing from about 3s to about 0.5s.
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