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Posted to issues@solr.apache.org by "Mike Drob (Jira)" <ji...@apache.org> on 2022/02/04 15:34:00 UTC
[jira] [Commented] (SOLR-15558) Solr stop doesn't handle zombie processes
[ https://issues.apache.org/jira/browse/SOLR-15558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17487128#comment-17487128 ]
Mike Drob commented on SOLR-15558:
----------------------------------
[~janhoy] - candidate for 9.0 (and 8.11.2 while we're at it)
> Solr stop doesn't handle zombie processes
> -----------------------------------------
>
> Key: SOLR-15558
> URL: https://issues.apache.org/jira/browse/SOLR-15558
> Project: Solr
> Issue Type: Bug
> Reporter: Colvin Cowie
> Priority: Trivial
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> When calling solr stop on linux, this command is used
> _CHECK_PID=`ps auxww | awk '\{print $2}' | grep -w $SOLR_PID | sort -r | tr -d ' '`_
> [https://github.com/apache/solr/blob/122c88a0748769432ef62cc3fb94c2226dd67aa7/solr/bin/solr#L871]
>
> If Solr has stopped but remains as a zombie process then its process entry will remain in the table, so _ps auxww_ will continue to show the PID even after kill -9. So that results in something like this, with 3 minutes wasted waiting for a dead process to exit.
>
> _[2021-07-21T09:15:12.365Z] Sending stop command to Solr running on port 8983 ... waiting up to 180 seconds to allow Jetty process 12622 to stop gracefully._
> _[2021-07-21T09:18:13.551Z] [|] Solr process 12622 is still running; jstacking it now._
> _[2021-07-21T09:18:21.806Z] 12622: Unable to open socket file /proc/12622/root/tmp/.java_pid12622: target process 12622 doesn't respond within 10500ms or HotSpot VM not loaded_
> _[2021-07-21T09:18:21.806Z] Solr process 12622 is still running; forcefully killing it now._
> _[2021-07-21T09:18:21.806Z] Killed process 12622_
> _[2021-07-21T09:18:31.678Z] ERROR: Failed to kill previous Solr Java process 12622 ... script fails._
>
> But the output of ps auxww does identify Zombie processes under STAT:
> _USER PID %CPU %MEM VSZ RSS TTY *STAT* START TIME COMMAND_
> _root 12622 1.4 0.0 0 0 pts/1 *Z* 10:42 0:26 [java] *<defunct>* _
>
> So the CHECK_PID could filter out Zombies.
> Obviously the bigger issue is why the process has ended up as a Zombie (in this case it was because of [https://blog.phusion.nl/2015/01/20/docker-and-the-pid-1-zombie-reaping-problem/] and not specifying "--init" when running Solr inside a docker container) so maybe a message warning that the process is a zombie is worth having, so that the user has an opportunity to do something about it.
>
> Note from [~mdrob]
> {quote}That seems like a reasonable check to add, the only caution I would advise
> is that a lot of developers use macs for local testing so make sure that
> whatever flags you invoke are generally cross platform compatible, or
> hidden behind appropriate conditions.{quote}
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