From: Stanimir Simeonoff:

<<
On leaks. The c-tor of LogManager leaks the thread group and the current AccessControlContext till JVM shutdown. The constructor code should be something like the one below with Cleaner getting ThreadGroup in its c-tor as well.


    java.security.AccessController.doPrivileged(//zip thread.inheritedAccessControlContext
        new java.security.PrivilegedAction<Void>() {
        public Void run() {
            // put the cleaner in the systsm threadgroup
            ThreadGroup grp = Thread.currentThread().getThreadGroup();
            for(ThreadGroup parent;null!=(parent = grp.getParent());) {
                grp = parent;
            }

            Cleaner cleaner = new Thread(grp);
            cleaner.setContextClassLoader(null);//zip the classloader
           
            // Add a shutdown hook to close the global handlers.
            try {
                Runtime.getRuntime().addShutdownHook(cleaner);
            } catch (IllegalStateException e) {
                // If the VM is already shutting down,
                // We do not need to register shutdownHook.
            }

            return null;
        }
    });
>>

see http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-September/028667.html