[jira] [Commented] (LOG4J2-3646) Log4jBridgeHandler does not work OTB on Tomcat 10.1

["Piotr Karwasz (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LOG4J2-3646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17653853#comment-17653853 ] 

Piotr Karwasz commented on LOG4J2-3646:
---------------------------------------

[~matthewfirth],

JUL has no concept of logger context. Tomcat solves this by making {{Logger.getLogger}} a context-sensitive method.
If your application has no {{logging.properties}} file in the webapp classloader, Tomcat attaches the root logger of your application's "logger context" to the root logger of the "global logger context". I don't see anything wrong in this (the main problem is JUL).

I agree that calling `setUseParentHandlers(false)` (even unconditionally) is the right thing to do. Can you send a PR on Github with your fix and a unit test? You can find a similar unit test in {{slf4j-to-jul}}: {{org.apache.logging.log4j.tojul.JULLoggerTest}}

> Log4jBridgeHandler does not work OTB on Tomcat 10.1
> ---------------------------------------------------
>
>                 Key: LOG4J2-3646
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-3646
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: JUL adapter
>    Affects Versions: 2.19.0
>            Reporter: Matthew Firth
>            Priority: Minor
>
> Related to the issue I filed in the Tomcat Bugzilla: [https://bz.apache.org/bugzilla/show_bug.cgi?id=66406] 
> The Log4jBridgeHandler's logic to clear existing handlers on the root logger doesn't work in TC 10 and possibly other situations.   The result is that I get all log messages published twice - once to the console by JUL and then once again by log4j.
> Log4jBridgeHandler.getJulRootLogger() assumes that the "root logger" is the one returned by getLogger("").   
> When running TC10 with JULI (the default), that Logger actually has two parents - and the grand-parent Logger has the Console Handler attached to it.
> Even if the Tomcat Project doesn't change JULI, I suggest log4j could be defensive and simply block parent loggers if any exist.
> For example - ammending Log4jBridgeHandler.install() like this:
> {noformat}
> if (removeHandlersForRootLogger) {
>    for (java.util.logging.Handler hdl : rootLogger.getHandlers()) {
>      rootLogger.removeHandler(hdl);
>     }
>    
>    if (rootLogger.getParent() != null)
>      rootLogger.setUseParentHandlers(false);
>    rootLogger.addHandler(new Log4jBridgeHandler(false, suffixToAppend, propagateLevels));
> }
>  
> {noformat}
>  
>  
> ) 



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