Julien Le Goff wrote: > Hi everyone, > > Today I came accross a behaviour I did not expect in python (I am using > 2.7). In my program, random.random() always seemed to return the same > number; it turned out to be related to the fact that I was using os.fork. > > See below a small program that illustrates this. It is easily fixed, but > I'm interested in knowing why this happens. Can anybody give me a hint? > Thanks!
Those numbers are "pseudo"-random numbers -- the sequence of numbers generated is fully determined by the state of the random number generator. That state like anything else is copied by fork(). I you need "better" randomness you can use random.SystemRandom: > import random > import os random = random.SystemRandom() > for i in xrange(10): > pid = os.fork() > if pid == 0: > # uncommenting this fixes the problem > # random.seed(os.getpid()) > print random.random() > os._exit(0) > > os.wait() -- http://mail.python.org/mailman/listinfo/python-list
