Michal Klempa commented on NIFI-2199:

[~trixpan] yes, i have the fixes for all versions since 0.5.0, but it is 
possible to submit a 'hotfix' to a released version? If it is so, tell me the 
right branches to which I should propose pull requests then and I will prepare 
pull requests.

> NiFi cannot be restarted through SSH (nifi.sh hangs)
> ----------------------------------------------------
>                 Key: NIFI-2199
>                 URL: https://issues.apache.org/jira/browse/NIFI-2199
>             Project: Apache NiFi
>          Issue Type: Bug
>          Components: Core Framework
>    Affects Versions: 1.0.0, 0.5.1, 0.7.0, 0.6.1
>            Reporter: Michal Klempa
>            Priority: Minor
>              Labels: initscript
> When NiFi is to restarted using SSH from remote host, nifi.sh causes SSH to 
> hang on open io streams.
> Steps to reproduce:
> 1. HostA - NiFi instalation
> 2. HostB - client machine
> 3. log to HostB
> 4. issue a command
> {code}
> ssh root@HostA /etc/init.d/nifi restart
> {code}
> Expected behavior: NiFi is restarted, SSH command exits with 0
> Actual behavior: NiFi is restarted, SSH command hang on
> This seems to be somehow related to SSH handling IO streams of process. Seems 
> like detached NiFi java process does not close stdin/out/err (i do not know 
> precisely) leading to sshd waiting for some input/output to come to client.
> I was able to do a quick&dirty fix in nifi.sh as follows:
> 1. on existing nifi installation, in file /etc/init.d/nifi find the line
> {code}
> (cd "${NIFI_HOME}" && ${sudo_cmd_prefix} "${JAVA}" -cp 
> "${BOOTSTRAP_CLASSPATH}" -Xms12m -Xmx24m 
> -Dorg.apache.nifi.bootstrap.config.file="${BOOTSTRAP_CONF}" 
> org.apache.nifi.bootstrap.RunNiFi $@ &)
> {code}
> its line number 214 (true branch of if [ "$1"] = "start"] condition).
> 2. replace it by line:
> {code}
> (cd "${NIFI_HOME}" && ${sudo_cmd_prefix} "${JAVA}" -cp 
> "${BOOTSTRAP_CLASSPATH}" -Xms12m -Xmx24m 
> -Dorg.apache.nifi.bootstrap.config.file="${BOOTSTRAP_CONF}" 
> org.apache.nifi.bootstrap.RunNiFi $@ > /dev/null 2>&1 < /dev/null &)
> {code}
> This simply redirects stdin from /dev/null to NiFi java process and redirects 
> stdout/err to /dev/null letting SSH to close the session.
> After applying this fix, I am able to restart NiFi remotely using SSH.
> Use case for this scenario: When Flow Manager develop flow.xml.gz on 
> localhost/testing environments, usually deployment to production environment 
> is handled by jenkins/bamboo CI tools. These tools need to log in, upload new 
> flow.xml.gz and restart NiFi. All remotely using SSH.
> If somebody can advice me where in the source code is this line of code 
> located, I can prepare a pull request for this quick&dirty fix.
> But. Maybe we may want to go further and investigate what to do with IO 
> streams inside Java...

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