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https://issues.apache.org/jira/browse/HADOOP-3280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12590531#action_12590531
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Arun C Murthy commented on HADOOP-3280:
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I guess HADOOP-2765 missed the use case that the 32-bit/64-bit java Map-Reduce
framework could inter-op with 32-bit/64-bit streaming/pipes processes... but we
*do* need to set a limit, and cannot rely on the pipes/streaming task to do it
- many apps don't and then proceed to hog the cluster.
Should we just add another config called mapred.child.ulimit? (sigh! I know I
don't want to do this... *smile*)
For now (i.e. for 0.17.0) mapred.child.ulimit could just provide the memory
limit, in future we can probably extend it to be a comma-separated list of
key/value pairs for memory, cpu, open files etc.
Thoughts?
> virtual address space limits break streaming apps
> -------------------------------------------------
>
> Key: HADOOP-3280
> URL: https://issues.apache.org/jira/browse/HADOOP-3280
> Project: Hadoop Core
> Issue Type: Bug
> Components: contrib/streaming
> Reporter: Rick Cox
> Priority: Blocker
> Fix For: 0.17.0
>
>
> HADOOP-2765 added a mandatory, hard virtual address space limit to streaming
> apps based on the Java process's -Xmx setting.
> This makes it impossible to run a 64-bit streaming app that needs large
> address spaces under a 32-bit JVM, even if one is otherwise willing to
> dramatically increase the -Xmx setting without cause. Also, unlike Java's
> -Xmx limit, the virtual address space limit for an arbitrary UNIX process
> does not necessarily correspond to RAM usage, so it's likely to be a
> relatively difficult to configure limit.
> 2765 was originally opened to allow an optional wrapper script around
> streaming tasks, one use case for which was setting a ulimit. That approach
> seems much less intrusive and more flexible than the final implementation.
> The ulimit can also be trivially set by the streaming task itself without any
> support from Hadoop.
> Marking this as an 0.17 blocker because it will break deployed apps and there
> is no workaround available.
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