Free a Context acquired by getCacheContext(). If Context was taken from the pool, it will be
returned to it. Otherwise, it was allocated on demand, and will be collected by the JVM GC.
Make sure to call this method from within a finally block to release any acquired Contexts.
ctx - A Context object in use, and to be freed.
public void closeAllContexts()
close all contexts free and occupied, waits until all Contexts are returned.