Arun C Murthy created MAPREDUCE-5108:
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Summary: 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 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.
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