thread-safe random

diff --git a/wtem/models.py b/wtem/models.py
index 6440e70..fbf0928 100644 (file)
--- a/wtem/models.py
+++ b/wtem/models.py
@@ -96,8 +96,8 @@ class Submission(models.Model):
 
     def shuffled_exercise_ids(self):
         exercise_ids = [e['id'] for e in exercises]
-        random.seed(self.random_seed)
-        random.shuffle(exercise_ids)
+        seeded_random = random.Random(self.random_seed)
+        seeded_random.shuffle(exercise_ids)
         return exercise_ids
 
     def current_exercise(self):