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https://issues.apache.org/jira/browse/OOZIE-3354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16631842#comment-16631842
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Peter Bacsko commented on OOZIE-3354:
-------------------------------------
+1
> [core] [SSH action] SSH action gets hung
> ----------------------------------------
>
> Key: OOZIE-3354
> URL: https://issues.apache.org/jira/browse/OOZIE-3354
> Project: Oozie
> Issue Type: Bug
> Components: action, core
> Affects Versions: 5.0.0
> Reporter: Andras Piros
> Assignee: Andras Piros
> Priority: Major
> Fix For: 5.1.0
>
> Attachments: OOZIE-3354.001.patch, OOZIE-3354.002.patch,
> OOZIE-3354.003.patch
>
>
> In OOZIE-3183 {{SshActionExecutor#drainBuffers()}} has changed. Previously,
> it called {{Process#exitCode()}} that would return immediately either with
> the exit code, or would throw an {{IllegalThreadStateException}} if the
> process would still be running.
> In the current implementation introduced by OOZIE-3183, {{Process#waitFor()}}
> is used that would block until the process finishes. Given the fact that
> sometime {{SshActionExecutor#check()}} calls {{ssh ... cat stdout}}, and this
> SSH process can be trapped even after {{cat stdout}} has been finished on the
> target host, it can happen that {{SshActionExecutor#drainBuffers()}} waits
> indefinitely without a chance to gather any {{stdout}} or {{stderr}} logs.
> Hence this particular one is a compatibility breaking change with existing
> SSH action behavior.
> Let's re-introduce the former behavior in
> {{SshActionExecutor#drainBuffers()}} that keeps polling
> {{Process#exitValue()}} and reading the progress on {{stdout}} and {{stderr}}
> till the process finishes, for backwards compatibility.
> [This
> article|https://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html]
> covers the behavioral details of {{Process#waitFor()}}.
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