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https://issues.apache.org/jira/browse/HADOOP-13709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15591860#comment-15591860
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Daryn Sharp commented on HADOOP-13709:
--------------------------------------
This approach will cause a memory leak and eventually lead to an unrecoverable
OOM. The shutdown thread instances and the Shell instances referenced by said
threads will not be garbage collected until shutdown.
A way to avoid this is Shell instances registering themselves in a static
collection via the ctor. A single shutdown hook will destroy all the Shell
instances in the collection. The remaining issue is removing completed Shell
instances to avoid a similar leak. It's probably not safe to assume the Shell
instance can be trusted to always remove itself so using a WeakHashMap is
probably the safest approach.
> 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, HADOOP-13709.002.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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