From: Raymond Hettinger <python@rcn.com>
Date: Sat, 9 Aug 2003 18:20:16 +0000 (+0000)
Subject: SF bug #778964:  bad seed in python 2.3 random
X-Git-Tag: v2.3.1~165
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8cf915e9fb83678e9715394d0a5c4bb8221852f8;p=thirdparty%2FPython%2Fcpython.git

SF bug #778964:  bad seed in python 2.3 random

The default seed is time.time().
Multiplied by 256 before truncating so that fractional seconds are used.
This way, two consequetive calls to random.seed() are much more likely
to produce different sequences.
---

diff --git a/Lib/random.py b/Lib/random.py
index 1a0b8f341e47..b1d13c0dfb59 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -94,6 +94,9 @@ class Random(_random.Random):
         If a is not None or an int or long, hash(a) is used instead.
         """
 
+        if a is None:
+            import time
+            a = long(time.time() * 256) # use fractional seconds
         super(Random, self).seed(a)
         self.gauss_next = None
 
diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
index ea2243d1de91..c9103e8f87b7 100644
--- a/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@ -20,7 +20,7 @@ class TestBasicOps(unittest.TestCase):
     def test_autoseed(self):
         self.gen.seed()
         state1 = self.gen.getstate()
-        time.sleep(1.1)
+        time.sleep(0.1)
         self.gen.seed()      # diffent seeds at different times
         state2 = self.gen.getstate()
         self.assertNotEqual(state1, state2)
diff --git a/Misc/NEWS b/Misc/NEWS
index b27ba1939efb..d3d229d7f653 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,6 +27,9 @@ Extension modules
 Library
 -------
 
+- Bug #778964:  random.seed() now uses fractional seconds so that
+  rapid successive, seeding calls will produce different sequences.
+
 - Bug #777664: Add Tkconstants.HIDDEN.
 
 - Bug #781065: test_normalization is updated to the current