[logback-dev] [JIRA] Commented: (LBCLASSIC-212) Logback classic doesn't work with Tomcat

Andy Duplain (JIRA) noreply-jira at qos.ch
Tue Jul 6 13:55:16 CEST 2010

    [ http://jira.qos.ch/browse/LBCLASSIC-212?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=11786#action_11786 ] 

Andy Duplain commented on LBCLASSIC-212:

I have now tried logback 0.9.24 and slf4j 1.6.1 with no change - the issue still exists.

> Logback classic doesn't work with Tomcat
> ----------------------------------------
>                 Key: LBCLASSIC-212
>                 URL: http://jira.qos.ch/browse/LBCLASSIC-212
>             Project: logback-classic
>          Issue Type: Bug
>    Affects Versions: 0.9.21
>            Reporter: Grzegorz Borkowski
>            Assignee: Logback dev list
>            Priority: Critical
> We have a web application running on Tomcat 6.0.26, which uses SLF4J for logging. Until now, we used SLF4J-Simple, and it worked very well. Now we try to switch to Logback, but we are not able to make it work. It works for logging one-line messages. But whenever any exception is thrown on server, which should print a stack trace, server hangs (It doesn't matter whether we actually print the stack trace in log or not). From what I was able to observe, it looks like it falls into endless loop, throwing "ClassNotFoundException: ch.qos.logback.classic.spi.ThrowableProxyUtil", which is caught and tried to be logged, which throws this exception again, and so on. I don't know why it throws this ClassNotFoundException - perhaps classloader issue? But even copying the logback jars to Tomcat's lib directory, I'm not able to run the application: than it has problems with starting up. Sometimes it freezes during loading web app, and often it helps to attach and detach debugger to Tomcat - it's a kind of magic... Anyway, it's horrendously painful, and I'm not able to make it work. Why such common setup (webapp on Tomcat) is not described in Logback documentation???
> This is our configuration file :
> <configuration scan="true">
>   <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
>     <!-- encoders are assigned the type
>          ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
>     <encoder>
>       <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n%ex</pattern>
>     </encoder>
>   </appender>
>   <root level="info">
>     <appender-ref ref="STDOUT" />
>   </root>
> </configuration>
>  (changing scan to "false" doesn't help. Also changing pattern  to  the one not containing "%ex" doesn't help)
> This is part of pom file related to logging:
>          <dependency>
>             <groupId>org.slf4j</groupId>
>             <artifactId>slf4j-api</artifactId>
>             <version>1.6.0</version>
>         </dependency>
>         <dependency>
>             <groupId>ch.qos.logback</groupId>
>             <artifactId>logback-classic</artifactId>
>             <version>0.9.21</version>
>             <scope>runtime</scope>
>         </dependency>
>         <!-- prevent JCL bundling into final WAR by using scope="provided" -->
>         <dependency>
>             <groupId>commons-logging</groupId>
>             <artifactId>commons-logging</artifactId>
>             <version>1.1.1</version>
>             <scope>provided</scope>
>         </dependency>
>         <!-- use this as adpater to satisfy dependencies on JCL -->
>         <dependency>
>             <groupId>org.slf4j</groupId>
>             <artifactId>jcl-over-slf4j</artifactId>
>             <version>1.6.0</version>
>         </dependency>
> If  we change dependency from logback to SLF4J simple (1.6.0) than everything works smoothly, stacktraces are printed to console, no freezing, everything is perfect.

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