I saw the loggerCache in class LoggerContext is a ConcurrentHashMap, how to free the instance in it.

There doesn’t seem to be a way to clear the cache. Normally this is not a problem as there is a finite, and small, number of loggers in any application. What are you trying to do? And why? You could suggest a change to logback. Or you could use an ugly reflection hack. You can change the loggerCache field to public via reflection, then you can get it and clear the entries. But bewarned this could easily cause problems if you upgrade logback later and don’t test properly. -- David