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From "Allen Wittenauer (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (MAPREDUCE-390) Corner case exists in detecting Java process deaths that might lead to orphan pipes processes lying around in memory
Date Thu, 17 Jul 2014 20:03:05 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Allen Wittenauer resolved MAPREDUCE-390.
----------------------------------------

    Resolution: Fixed

I believe this one has actually been resolved with the rewrite of the pipes interface.

> Corner case exists in detecting Java process deaths that might lead to orphan pipes processes
lying around in memory
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-390
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-390
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Devaraj Das
>            Priority: Minor
>
> In HADOOP-2092, the child pipes process periodically pings the parent Java process to
find out whether it is alive. The ping cycle is 5 seconds. Consider the following scenario:
> 1) The Java task dies at the beginning of the ping cycle
> 2) A new Java task starts and binds to the same port as the earlier Java task's port
> 3) The pipes process wakes up and does a ping - it will still be successful since the
port number hasn't changed
> This will lead to orphan processes lying around in memory. The detection of parent process
deaths can be made more reliable at least on Unix'ish platforms by checking whether the parent
process ID is 1, and if so exit. This will take care of the most common platform that hadoop
is run on. For non-unix platforms, the existing ping mechanism can be retained. Thoughts?



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