diff --git a/common/djangoapps/course_groups/cohorts.py b/common/djangoapps/course_groups/cohorts.py index c362ed4e89..7924012bfe 100644 --- a/common/djangoapps/course_groups/cohorts.py +++ b/common/djangoapps/course_groups/cohorts.py @@ -15,6 +15,24 @@ from .models import CourseUserGroup log = logging.getLogger(__name__) +# tl;dr: global state is bad. capa reseeds random every time a problem is loaded. Even +# if and when that's fixed, it's a good idea to have a local generator to avoid any other +# code that messes with the global random module. +_local_random = None + +def local_random(): + """ + Get the local random number generator. In a function so that we don't run + random.Random() at import time. + """ + # ironic, isn't it? + global _local_random + + if _local_random is None: + _local_random = random.Random() + + return _local_random + def is_course_cohorted(course_id): """ Given a course id, return a boolean for whether or not the course is @@ -129,13 +147,7 @@ def get_cohort(user, course_id): return None # Put user in a random group, creating it if needed - choice = random.randrange(0, n) - group_name = choices[choice] - - # Victor: we are seeing very strange behavior on prod, where almost all users - # end up in the same group. Log at INFO to try to figure out what's going on. - log.info("DEBUG: adding user {0} to cohort {1}. choice={2}".format( - user, group_name,choice)) + group_name = local_random().choice(choices) group, created = CourseUserGroup.objects.get_or_create( course_id=course_id,