Caching instances of Slf4j-Loggers prevents Logback-ContextSelectors from working. (See also SLF4J-282 for a similar issue with the log4j bridge.)

The caching code can be found in org.apache.commons.logging.impl.SLF4JLogFactory:

public Log getInstance(String name) throws LogConfigurationException {
Log instance = null;
// protect against concurrent access of loggerMap
synchronized (loggerMap) {
instance = (Log) loggerMap.get(name);
if (instance == null) {
Logger logger = LoggerFactory.getLogger(name);
if(logger instanceof LocationAwareLogger)

{ instance = new SLF4JLocationAwareLog((LocationAwareLogger) logger); }

else

{ instance = new SLF4JLog(logger); }

loggerMap.put(name, instance);
}
}
return (instance);

}