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https://issues.apache.org/jira/browse/NIFI-5024?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16417551#comment-16417551
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ASF GitHub Bot commented on NIFI-5024:
--------------------------------------
GitHub user nsanglar opened a pull request:
https://github.com/apache/nifi/pull/2591
NIFI-5024 Resolves deadlock issue with stderr
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You can merge this pull request into a Git repository by running:
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Alternatively you can review and apply these changes as the patch at:
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This closes #2591
----
commit 2e200c7c6f4d0bb4b15691c3fc5221789b1523e5
Author: Nicolas Sanglard <nicolas@...>
Date: 2018-03-28T15:26:29Z
NIFI-5024 Resolves deadlock issue with stderr
----
> Deadlock in ExecuteStreamCommand processor
> ------------------------------------------
>
> Key: NIFI-5024
> URL: https://issues.apache.org/jira/browse/NIFI-5024
> Project: Apache NiFi
> Issue Type: Bug
> Affects Versions: 1.3.0
> Reporter: Nicolas Sanglard
> Priority: Minor
> Attachments: Screen Shot 2018-03-28 at 15.34.36.png, Screen Shot
> 2018-03-28 at 15.36.02.png
>
>
> Whenever a process is producing too much output on stderr, the current
> implementation will run into a deadlock between the JVM and the unix process
> started by the ExecuteStreamCommand.
> This is a known issue that is fully described here:
> [http://java-monitor.com/forum/showthread.php?t=4067]
> In short:
> * If the process produces too much stderr that is not consumed by
> ExecuteStreamCommand, it will block until data is read.
> * The current processor implementation is reading from stderr only after
> having called process.waitFor()
> * Thus, the two processes are waiting for each other and fall into a deadlock
>
>
> The following setup will lead to a deadlock:
>
> A jar containing the following Main application:
> {code:java}
> object Main extends App {
> import scala.collection.JavaConverters._
> val str =
> Source.fromInputStream(this.getClass.getResourceAsStream("/1mb.txt")).mkString
> System.err.println(str)
> }
> {code}
> The following NiFi Flow:
>
> !Screen Shot 2018-03-28 at 15.34.36.png!
>
> Configuration for ExecuteStreamCommand:
>
> !Screen Shot 2018-03-28 at 15.36.02.png!
>
> The script is simply containing a call to the jar:
> {code:java}
> java -jar stderr.jar
> {code}
>
> Once the processor calls the script, it appears as "processing" indefinitely
> and can only be stopped by restarting NiFi.
>
> I already have a running solution that I will publish as soon as possible.
>
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