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https://issues.apache.org/jira/browse/HADOOP-3280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12591217#action_12591217
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Sameer Paranjpye commented on HADOOP-3280:
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The prologue setting, if implemented, should IMO apply in all task contexts:
streaming, pipes or plain old Java. I don't think that it should default to
setting a memory limit based on -Xmx. The -Xmx switch can be used if needed in
JVM args to specify a threshold that triggers garbage collection. It can, for
example, be set to a value lower than a memory limit specified through a
ulimit.
> PipeMapRed uses a shell post-HADOOP-2765 to set the ulimits, but doesn't need
> to assume a particular shell otherwise.
The ulimit was certainly introduced in HADOOP-2765, but the
_TaskLog.captureOutAndErr_ method has existed and assumed bash for quite a
while now. I believe the consensus at the time was that assuming bash was
pretty benign.
> 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
> Assignee: Amareshwari Sriramadasu
> Priority: Blocker
> Fix For: 0.17.0
>
> Attachments: HADOOP-3280_0_20080418.patch
>
>
> 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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