Major Description
If you remove all log4j.properties from classpath (and prvent any log4j intialization previous to the one which involves kafka appender), and put KAFKA appender on rootLogger, then, even if you exclude the KAFKA appender from logger.kafka and logger.org, you get a Log4j deadlock when zookeeper send thread tries to issue a LOG.info, and for that it locks the root category (as its correct category, say org, is not yet set up in log4j, who is still in activateOptions on kafka appender).
please read comments on the parent and ask any questions to nmarasoi@adobe.com