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https://issues.apache.org/jira/browse/MAPREDUCE-326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12830867#action_12830867
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eric baldeschwieler commented on MAPREDUCE-326:
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I'm very interested in proposals for how this can be done. If it can be done
in a performance and API neutral way, than yes, interested parties should
pursue it.
The issue here is just that we need to hold a reasonably high bar on
performance and API changes at this point. Incremental checkins that change
user facing APIs in a non-backwards compatible way are a challenge. Ditto
performance regressions. I owe the community a blog post on the challenges we
are facing with our user base on backwards compatibility and why this has lead
us to choose not to deploy the 21 release at Yahoo.
When I suggest it might be better to defer this work, it is looking at it
through that lens. And that is the lens I suggest reviewers use considering
patches in this area. Hope that clarifies things! Go forth and propose
improvements in this area, I'm a fan. Just be aware that since hadoop's users
are demanding we behave as if hadoop is 1.0, think about supporting them while
thinking about how to manage this.
> The lowest level map-reduce APIs should be byte oriented
> --------------------------------------------------------
>
> Key: MAPREDUCE-326
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-326
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: eric baldeschwieler
>
> As discussed here:
> https://issues.apache.org/jira/browse/HADOOP-1986#action_12551237
> The templates, serializers and other complexities that allow map-reduce to
> use arbitrary types complicate the design and lead to lots of object creates
> and other overhead that a byte oriented design would not suffer. I believe
> the lowest level implementation of hadoop map-reduce should have byte string
> oriented APIs (for keys and values). This API would be more performant,
> simpler and more easily cross language.
> The existing API could be maintained as a thin layer on top of the leaner API.
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