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https://issues.apache.org/jira/browse/MAPREDUCE-4049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13256720#comment-13256720
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Mariappan Asokan commented on MAPREDUCE-4049:
---------------------------------------------
Hi Avner,
Following are my additional comments and thoughts:
* Does someone need to implement {{ShuffleProviderPlugin}} and
{{ShuffleConsumerPlugin}} as a pair? Or can one of them be implemented and the
other be left to the default implementaion?
* For the trunk version, the shuffle provider will probably not require any
changes. The shuffle consumer on the other hand has to be separated into two
parts: one that deals with tansferring map output data across the network and
the other that consumes the transferred data. If you look at the patch I
posted in MAPREDUCE-2454, the above are abstracted as {{ShuffleRunner}} and
{{ShuffleCallback}} interfaces respectively. In the refactored code as part of
the patch, {{MergeManager}} class implements {{ShuffleCallback}} and
{{Shuffle}} class implements {{ShuffleRunner}}. I can probably enhance the
{{ShuffleRunner}} interface as below with an added {{initialize()}} method
which basically gets all the arguments that current {{Shuffle}} constructor
gets:
{code:title=ShuffleRunner.java}
public interface ShuffleRunner extends ExceptionReporter {
public void initialize(TaskAttemptID reduceId, JobConf jobConf,
TaskUmbilicalProtocol umbilical,
Reporter reporter,
Counters.Counter shuffledMapsCounter,
Counters.Counter reduceShuffleBytes,
Counters.Counter failedShuffleCounter,
TaskStatus status,
Progress copyPhase,
Task reduceTask);
public void run(ShuffleCallback shuffleCallback)
throws IOException, InterruptedException;
}
{code}
* If you want to implement your own merge(using RDMA to get shuffled data as
described in the technical paper attached to this Jira) you can implement the
interface {{ReduceSortPlugin}} in addition to {{ShuffleRunner}}. In the
{{ReduceSortPlugin}} your merge class can implement {{ShuffleCallback}}.
Currently, since the merge and shuffle are running in separate threads, the
synchronization is done by {{waitForResource()}} method in
{{ShuffleCallback}}. If you are using RDMA to fetch map outputs, your merge
will be in full control. It has to coordinate with your implementation of
{{ShuffleRunner}} to fetch specific mapper output you want in the merge.
If you have any questions, please let me know.
> plugin for generic shuffle service
> ----------------------------------
>
> Key: MAPREDUCE-4049
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4049
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: performance, task, tasktracker
> Affects Versions: 1.0.3
> Reporter: Avner BenHanoch
> Labels: merge, plugin, rdma, shuffle
> Attachments: HADOOP-1.0.2.patch, HADOOP-1.0.x.patch,
> HADOOP-1.0.x.patch, Hadoop Shuffle Consumer Plugin TLD.rtf, Hadoop Shuffle
> Provider Plugin TLD.rtf, MAPREDUCE-4049-branch-1.0.2.patch, mapred-site.xml,
> mapred.diff, src.tgz, test.diff
>
>
> Support generic shuffle service as set of two plugins: ShuffleProvider &
> ShuffleConsumer.
> This will satisfy the following needs:
> # Better shuffle and merge performance. For example: we are working on
> shuffle plugin that performs shuffle over RDMA in fast networks (10gE, 40gE,
> or Infiniband) instead of using the current HTTP shuffle. Based on the fast
> RDMA shuffle, the plugin can also utilize a suitable merge approach during
> the intermediate merges. Hence, getting much better performance.
> # Satisfy MAPREDUCE-3060 - generic shuffle service for avoiding hidden
> dependency of NodeManager with a specific version of mapreduce shuffle
> (currently targeted to 0.24.0).
> References:
> # Hadoop Acceleration through Network Levitated Merging, by Prof. Weikuan Yu
> from Auburn University with others,
> [http://pasl.eng.auburn.edu/pubs/sc11-netlev.pdf]
> # I am attaching 2 documents with suggested Top Level Design for both plugins
> (currently, based on 1.0 branch)
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