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https://issues.apache.org/jira/browse/HADOOP-9639?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13682657#comment-13682657
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Sangjin Lee commented on HADOOP-9639:
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[~jlowe] thanks for the comment. Your points are taken, and there may well be
some quick actions we can take (and code) to take care of a chunk of our use
cases.
Having said that, we're still dealing with a fair amount of variety of MR jobs;
pig v. scalding, etc., and job jars with all dependencies embedded v. thin job
jars with libjars, and so on. Also, as we start addressing more use cases, the
management issues will come to fore eventually anyway...
I'd like to take a stab at some rough design to see if we can find a solution
that stays simple and low risk, and leverages all the existing distributed
cache API and the resource localization service. I'll share more when we have
some more details. I'd appreciate additional feedback or suggestions on the
idea!
> truly shared cache for jars (jobjar/libjar)
> -------------------------------------------
>
> Key: HADOOP-9639
> URL: https://issues.apache.org/jira/browse/HADOOP-9639
> Project: Hadoop Common
> Issue Type: New Feature
> Components: filecache
> Affects Versions: 2.0.4-alpha
> Reporter: Sangjin Lee
>
> Currently there is the distributed cache that enables you to cache jars and
> files so that attempts from the same job can reuse them. However, sharing is
> limited with the distributed cache because it is normally on a per-job basis.
> On a large cluster, sometimes copying of jobjars and libjars becomes so
> prevalent that it consumes a large portion of the network bandwidth, not to
> speak of defeating the purpose of "bringing compute to where data is". This
> is wasteful because in most cases code doesn't change much across many jobs.
> I'd like to propose and discuss feasibility of introducing a truly shared
> cache so that multiple jobs from multiple users can share and cache jars.
> This JIRA is to open the discussion.
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