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From "Ralph Goers (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LOG4J2-702) LoggerConfig#waitForCompletion is not thread safe
Date Sun, 13 Jul 2014 00:03:04 GMT

    [ https://issues.apache.org/jira/browse/LOG4J2-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14059962#comment-14059962
] 

Ralph Goers commented on LOG4J2-702:
------------------------------------

Yes, it would be undesirable.  But the only time the retry should fail is if the PrivateConfig
is attached to a Configuration that is once again marked as stopping. I would at least put
a sleep for 10 milliseconds in the loop but I think looping for a fixed number of times and
then throwing an exception would be fine as that would imply something bizarre is going on,
as every iteration through the loop should be getting a new PrivateLogger since the one in
use has a Configuration that is stopping.

> LoggerConfig#waitForCompletion is not thread safe
> -------------------------------------------------
>
>                 Key: LOG4J2-702
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-702
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 2.0-rc2
>            Reporter: Sean Bridges
>            Assignee: Matt Sicker
>            Priority: Critical
>             Fix For: 2.0
>
>
> This is in trunk, svn commit 1608156
> LoggerConfig#waitForCompletion uses an AtomicInteger counter to try to detect if there
are any calls currently executing the log(Event) method, but it does not do so in a thread
safe manner.  Consider two threads A and B, where Thread A is calling clearAppenders(), and
Thread B is calling log(Event),
> {code}
> Thread A  loggerConfig.clearAppenders()
> Thread A  loggerConfig.waitForCompletion()
> Thread A  counter.get() //returns 0
> Thread A  //loggerConfig.waitForCompletion() returns
> Thread B  loggerConfig.log(Event)
> Thread B  counter.increment()
> Thread A  proceeds assuming no log calls are onging, but thread B is in the log method
> {code}
> I'm not sure what the requirements are, but if the requirement is to not lose logging
events, I think you need some sort of synchronization outside of the LoggerConfig object.
 



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