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https://issues.apache.org/jira/browse/MAPREDUCE-5108?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhijie Shen resolved MAPREDUCE-5108.
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Resolution: Fixed
Close the ticket as all the subtasks are closed.
> Changes needed for Binary Compatibility for MR applications via YARN
> --------------------------------------------------------------------
>
> Key: MAPREDUCE-5108
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5108
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Affects Versions: 2.0.3-alpha
> Reporter: Arun C Murthy
> Assignee: Zhijie Shen
> Priority: Blocker
> Attachments: Binary Backward Compatibility.pdf,
> mr1_mr2_api_diff.tar.gz, MR_API_DIFF_v2.tar.gz
>
>
> As we get ready to ship out a beta/stable version of hadoop-2, it makes sense
> to spend time reviewing support for existing MR applications (hadoop-1) to
> migrate seamlessly.
> We've done various pieces of work over time, let's track progress and
> document things clearly. [~zjshen] has done a bunch of testing and results
> look very promising so far.
> The aim is to support applications using org.apache.hadoop.mapred.* api in a
> binary compatible manner in hadoop-2 - thus, users can just take existing MR
> applications jars, point them at YARN clusters and things just work.
> Clearly, we might have some corner cases (haven't seen many so far),
> including semantics (not just apis); however the intent is to, at least,
> document them throughly if not actually fix them as feasible.
> Also, it's clear that we will *not* be able to support
> org.apache.hadoop.mapreduce api in a *binary compatible* manner due to the
> interface changes we made in hadoop-0.21 (sigh), and hence, users using the
> _new_ apis will have to re-compile (i.e. source compatible only).
> Net, given that vast majority of users use the org.apache.hadoop.mapred api,
> it's a very reasonable way to ease migration to hadoop-2.
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