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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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Arun C Murthy updated MAPREDUCE-5108:
-------------------------------------
Description:
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.
was:
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 due to the interface changes we made in
hadoop-0.21 (sigh), but given that vast majority of users use the mapred api,
it's a reasonable step to easing migration.
> Review support 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
> Fix For: 2.0.5-beta
>
>
> 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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