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https://issues.apache.org/jira/browse/HADOOP-13709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15573435#comment-15573435
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Jason Lowe commented on HADOOP-13709:
-------------------------------------
Good catch, Daryn! I missed the memory-model races introduced by moving the
stdout processing to a new thread. We could fix that with appropriate
synchronization in the derived classes. However Shell is explicitly marked
Public, so it's prudent to avoid disrupting that too much.
It would be really nice to be able to kill the subprocess if the thread
executing Shell is interrupted, but without moving the stdout processing to
another thread I don't see a good way to do that. Reading from a stream
doesn't seem to be interruptible in practice. If we can't make the Shell
command reliably interruptible then the next best thing is to make sure we
don't leave them lingering when this process exits so we can fix the problem
described in YARN-5641. Having a live Shell list that we can traverse on
shutdown should fix that particular issue.
> Clean up subprocesses spawned by Shell.java:runCommand when the shell process
> exits
> -----------------------------------------------------------------------------------
>
> Key: HADOOP-13709
> URL: https://issues.apache.org/jira/browse/HADOOP-13709
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 2.2.0
> Reporter: Eric Badger
> Assignee: Eric Badger
> Attachments: HADOOP-13709.001.patch
>
>
> The runCommand code in Shell.java can get into a situation where it will
> ignore InterruptedExceptions and refuse to shutdown due to being in I/O
> waiting for the return value of the subprocess that was spawned. We need to
> allow for the subprocess to be interrupted and killed when the shell process
> gets killed. Currently the JVM will shutdown and all of the subprocesses will
> be orphaned and not killed.
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