I have many different java processes run by cron that do not exit and remain in memory after upgrading my 1.0.6 logback to any version beginning with 1.0.11 and up to 1.1.2 (the 1.0.10 was the last to not have the problem). The funny thing is, that every "script" uses some type of locking (file based or socket based) and when the process stucks, the next instance is started without a problem, that means the previous finished execution and released lock but was not terminated. Seems like some thread is stuck. I made a couple of thread dumps (attached) - may be you could see anything remarkable there. My logback configuration is nothing special, a file appender and a couple of email appenders. there are no errors during logback initialisation for any version

debian 6.0.10 x64
jdk-sun-1.6.0.26 x64