At the end, I think it is worthwhile to implement my own shuffle and random methods based on os.urandom. Not only does the resulting code gets rid of the minuscule bias, but the program also runs much faster.
When using random.SystemRandom.shuffle, posix.open and posix.close from calling os.urandom account for almost half of the total execution time for my program. By implementing my own random and getting a much larger chunk of random bytes from os.urandom each time, I am able to reduce the total execution time by half. -tooru honda P.S. I use python 2.5.1 on MacOSX 10.4.10 (PowerPC). -- http://mail.python.org/mailman/listinfo/python-list
