In the code snippet [1], public JMSSink( String tcfBindingName, String topicBindingName, String username, String password) creates a TopicConnection but does not close it in any situation. JMSSink needs to implement a close method to deal with the resource, doesn't it? [1]http://svn.apache.org/viewvc/logging/log4j/trunk/src/main/java/org/apache/log4j/net/JMSSink.java?revision=565523&view=markup