"java.lang.LinkageError: loader constraint violation" for logger

[x]

I'm seeing the following in my stash log (standalone, local) when using `atlas-install-plugin` for a newly created plugin:

2014-01-21 17:12:48,204 WARN  [UpmAsynchronousTaskManager:thread-2] admin 1032x8x0 1blz4pw 127.0.0.1 "POST /rest/plugins/1.0/ HTTP/1.1" c.a.p.u.r.AlternativeDirectoryResourceLoader Resource directory , which resolves to /private/tmp/amps-standalone/target/container/tomcat7x/cargo-stash-home does not exist
2014-01-21 17:12:48,264 ERROR [ThreadPoolAsyncTaskExecutor::Thread 16] admin 1032x8x0 1blz4pw 127.0.0.1 "POST /rest/plugins/1.0/ HTTP/1.1" c.a.plugin.osgi.factory.OsgiPlugin Unable to start the plugin container for plugin com.squareup.stash.group-mention-plugin
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'PullRequestListener' defined in URL [bundle://96.0:0/META-INF/spring/atlassian-plugins-components.xml]: Instantiation of bean failed; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.slf4j.impl.StaticLoggerBinder.getLoggerFactory()Lorg/slf4j/ILoggerFactory;" the class loader (instance of org/apache/felix/framework/ModuleImpl$ModuleClassLoaderJava5) of the current class, org/slf4j/LoggerFactory, and the class loader (instance of org/apache/catalina/loader/WebappClassLoader) for resolved class, org/slf4j/impl/StaticLoggerBinder, have different Class objects for the type org/slf4j/ILoggerFactory used in the signature
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:254) ~[spring-beans-3.2.5.RELEASE.jar:3.2.5.RELEASE]
	at java.security.AccessController.doPrivileged(Native Method) ~[na:1.6.0_65]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:728) ~[spring-context-3.2.5.RELEASE.jar:3.2.5.RELEASE]
	at java.lang.Thread.run(Thread.java:695) ~[na:1.6.0_65]
	... 18 frames trimmed
Caused by: java.lang.LinkageError: loader constraint violation: when resolving method "org.slf4j.impl.StaticLoggerBinder.getLoggerFactory()Lorg/slf4j/ILoggerFactory;" the class loader (instance of org/apache/felix/framework/ModuleImpl$ModuleClassLoaderJava5) of the current class, org/slf4j/LoggerFactory, and the class loader (instance of org/apache/catalina/loader/WebappClassLoader) for resolved class, org/slf4j/impl/StaticLoggerBinder, have different Class objects for the type org/slf4j/ILoggerFactory used in the signature
	at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:299) ~[slf4j-api-1.7.5.jar:1.7.5]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:269) ~[slf4j-api-1.7.5.jar:1.7.5]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:281) ~[slf4j-api-1.7.5.jar:1.7.5]
	at com.squareup.stash.PullRequestListener.<clinit>(PullRequestListener.java:19) ~[na:na]
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:100) ~[spring-beans-3.2.5.RELEASE.jar:3.2.5.RELEASE]
	... 4 common frames omitted
2014-01-21 17:12:48,268 ERROR [ThreadPoolAsyncTaskExecutor::Thread 16] admin 1032x8x0 1blz4pw 127.0.0.1 "POST /rest/plugins/1.0/ HTTP/1.1" o.s.o.e.i.a.ContextLoaderListener Application context refresh failed (NonValidatingOsgiBundleXmlApplicationContext(bundle=com.squareup.stash.group-mention-plugin, config=osgibundle:/META-INF/spring/*.xml))
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'PullRequestListener' defined in URL [bundle://96.0:0/META-INF/spring/atlassian-plugins-components.xml]: Instantiation of bean failed; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.slf4j.impl.StaticLoggerBinder.getLoggerFactory()Lorg/slf4j/ILoggerFactory;" the class loader (instance of org/apache/felix/framework/ModuleImpl$ModuleClassLoaderJava5) of the current class, org/slf4j/LoggerFactory, and the class loader (instance of org/apache/catalina/loader/WebappClassLoader) for resolved class, org/slf4j/impl/StaticLoggerBinder, have different Class objects for the type org/slf4j/ILoggerFactory used in the signature
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:254) ~[spring-beans-3.2.5.RELEASE.jar:3.2.5.RELEASE]
	at java.security.AccessController.doPrivileged(Native Method) ~[na:1.6.0_65]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:728) ~[spring-context-3.2.5.RELEASE.jar:3.2.5.RELEASE]
	at java.lang.Thread.run(Thread.java:695) [na:1.6.0_65]
	... 18 frames trimmed
Caused by: java.lang.LinkageError: loader constraint violation: when resolving method "org.slf4j.impl.StaticLoggerBinder.getLoggerFactory()Lorg/slf4j/ILoggerFactory;" the class loader (instance of org/apache/felix/framework/ModuleImpl$ModuleClassLoaderJava5) of the current class, org/slf4j/LoggerFactory, and the class loader (instance of org/apache/catalina/loader/WebappClassLoader) for resolved class, org/slf4j/impl/StaticLoggerBinder, have different Class objects for the type org/slf4j/ILoggerFactory used in the signature
	at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:299) ~[slf4j-api-1.7.5.jar:1.7.5]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:269) ~[slf4j-api-1.7.5.jar:1.7.5]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:281) ~[slf4j-api-1.7.5.jar:1.7.5]
	at com.squareup.stash.PullRequestListener.<clinit>(PullRequestListener.java:19) ~[na:na]
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:100) ~[spring-2.5.6.SEC02.jar:3.2.5.RELEASE]
	... 4 common frames omitted

Strangely, I have an old plugin lying around that uses the same logging classes/technique, but which installs fine. (It was created on a much older version of stash/atlas.)

I don't really know how to go about fixing this. Suggestions welcome!

My code:

package com.squareup.stash;

import com.atlassian.event.api.EventListener;
import com.atlassian.stash.event.pull.PullRequestUpdatedEvent;
import org.slf4j.LoggerFactory;
import org.slf4j.Logger;

public class PullRequestListener {
    private static final Logger log = LoggerFactory.getLogger(PullRequestListener.class);

    @EventListener
    public void myListener(PullRequestUpdatedEvent e) {
        log.debug("HOLA");
    }
}

Xavier

[cofarrell · Accepted solution]

Hi Xavier,

What does your pom.xml look like? Make sure you use <scope>provided</scope> for importing SLF4J, otherwise you're going to run into weird classpath problems.

Cheers,

Charles

[x]

I'm not explicitly importing SLF4J ... should I be?

https://gist.github.com/xaviershay/eab492d61998e8462cb5

[x]

Adding the following to my pom appears to have fixed the issue:

<dependency>
            <groupId>.org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.5</version>
            <scope>provided</scope>
        </dependency>

... though I don't really understand why.

[Damian Skrodzki]

Adding dependency by hand worked for me also.

[francis]

To add to the confusion Had the same problem. Adding the dependency on slf4j didn't resolve the problem, but changing the source and target version of the compiler did {code} <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>2.3.2</version> <configuration> <source>1.6</source> <target>1.6</target> </configuration> </plugin> {code}

[francis]

(I changed it back from 1.7 to 1.6)

[x]

.... I don't know how to fix the formatting in this post.