KAFKA-4931: stop script fails due 4096 ps output limit

[tombentley]

This also fixes KAFKA-4389 and KAFKA-4297, which were exactly the same
issue but for kafka-server-stop.sh.

[asfgit]

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[asfgit]

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[omkreddy]

AFAIK, jps tool is not available on IBM Java. not sure, if we can use this approach.

[tombentley]

I pushed a change so we use jps if it's available and fallback to using ps when it's not

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[omkreddy]

LGTM

[kamalcph]

If multiple Kafka brokers are running in the same machine, which one will it stop ?

Existing script using ps command have the same problem, but now it does nothing.

[tombentley]

@kamal15 it will kill all of them. Wdym "now it does nothing"?

[kamalcph]

No, it won't kill any server. Since the grep output is empty.

[tombentley]

@kamal15 which grep output (the jps or ps one?) and if the jps one what jre/jdk are you using?

[kamalcph]

@tombentley

Assume that multiple brokers are running in different ports in a machine. Earlier, on invoking sh kafka-server-stop.sh due to 4096 ps output limit, we will get "No kafka server to run". So, manually we have to kill / stop the server.

Now with your changes, jps command will definitely return a PID which may or mayn't be the intended broker to stop. I'm using oracle jdk 1.8.0_121

[tombentley]

@kamal15 but in environments where the 4096 limit was not hit the original script would have killed all the servers. So in that respect this patch doesn't change anything: The stop script still kills all the applicable server processes. There's a separate JIRA about this https://issues.apache.org/jira/browse/KAFKA-4110

[kamalcph]

@tombentley

Ok then. I'm un-aware of the Jira.