1. In a computing environment, a method comprising: receiving a raw stream of application program commands; transforming the raw stream of application program commands into a transformed sequence of application program commands by: reducing repeat application program commands in the raw stream of application program commands; grouping some application program commands in the raw stream together; and filtering out some noisy application program commands from the raw stream of application program commands; segmenting the transformed sequence of application program commands into units of application program commands; iteratively extracting stable patterns from the units of application program commands to identify stable pattern sets of frequently used combinations of application program commands, wherein the stable pattern sets are extracted by calculating weighted mutual information scores between succeeding units of application program commands; and outputting at least some of the stable pattern sets of frequently used combinations of application program commands, wherein at least iteratively extracting the stable patterns is performed by a processing unit.