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From "Remko Popma (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LOG4J2-1094) Multi thread initialization problem
Date Mon, 17 Aug 2015 14:36:46 GMT

    [ https://issues.apache.org/jira/browse/LOG4J2-1094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14699592#comment-14699592
] 

Remko Popma commented on LOG4J2-1094:
-------------------------------------

Bart, I do not think that your idea to support manual initialization would solve this Jira
ticket. This ticket is about a problem that occurs with automatic initialization in a multi-threaded
scenario. Since we cannot remove our support for automatic initialization, manual initialization
is not a solution.

However, it may still make sense to support manual initialization. If you think there is value
in supporting manual initialization in addition to the current automatic initialization, can
you create a separate Jira ticket that explains the pros and cons?

> Multi thread initialization problem
> -----------------------------------
>
>                 Key: LOG4J2-1094
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-1094
>             Project: Log4j 2
>          Issue Type: Bug
>    Affects Versions: 2.3
>            Reporter: Luca Burgazzoli
>
> I wrote a very simple example which has a behaviour I do not expect:
> If I call LogManager.getLogger(..) from two threads, only one of the loggers logs what
I'd expect but if I add an additional call to LogManager.getLogger(..) before the threads
are started, I see what I'd expect so it looks like there is a problem in multi threaded initialization.
> You can find the code and the configuration here:
> - https://github.com/lburgazzoli/lb-chronicle/blob/master/chronicle-examples/chronicle-logger-log4j2/src/main/java/com.github.lburgazzoli.openhft.examples.chronicle.logger.log4j2/MtLogging.java
> - https://github.com/lburgazzoli/lb-chronicle/blob/master/chronicle-examples/chronicle-logger-log4j2/src/main/resources/log4j2.xml
> {code}
> public class MtLogging {
>     public static void main(final String[] args) throws Exception {
>         //LogManager.getLogger("main");
>         Thread th1 = new Thread(() -> {
>             final String name = "thread-1";
>             final Logger log = LogManager.getLogger(name);
>             System.out.println("write " + name);
>             log.info("message");
>             System.out.println("done " + name);
>         });
>         Thread th2 = new Thread(() -> {
>             final String name = "thread-2";
>             final Logger log = LogManager.getLogger(name);
>             System.out.println("write " + name);
>             log.info("message");
>             System.out.println("done " + name);
>         });
>         th1.start();
>         th2.start();
>         th1.join();
>         th2.join();
>     }
> }
> {code}
> {code}
> <?xml version="1.0" encoding="UTF-8"?>
> <configuration>
>     <appenders>
>         <Console name="STDOUT" target="SYSTEM_OUT">
>             <PatternLayout pattern="[TEST] [%-5p] %c - %m%n%throwable{none}"/>
>         </Console>
>     </appenders>
>     <loggers>
>         <root level="all">
>             <appender-ref ref="STDOUT"/>
>         </root>
>     </loggers>
> </configuration>
> {code}
> The code above will show:
> {noformat}
>     write thread-1
>     done thread-1 
>     write thread-2
>     [TEST] [INFO ] thread-2 - message
>     done thread-2
> {noformat}
> Any call to LogManager makes it succeed (the problem no longer occurs):
> {code}
>     LogManager.getContext(false);
>     th1.start();
>     th2.start();
>     th1.join();
>     th2.join();
> {code}
> New output:
> {noformat}
>     write thread-2
>     write thread-1
>     [TEST] [INFO ] thread-2 - message
>    done thread-2
>    [TEST] [INFO ] thread-1 - message
>    done thread-1
> {noformat}
> The funny thing is that the first thread to arrive is initialized with ERROR level instead
of the ALL that is given to root. In other words it seems that the config has not loaded



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