bpo-36559: random module: optimize sha512 import (GH-12742)
The random module now prefers the lean internal _sha512 module over hashlib
for seed(version=2) to optimize import time.
Signed-off-by: Christian Heimes <christian@python.org>
diff --git a/Lib/random.py b/Lib/random.py
index 79ef30d..53981f3 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -42,11 +42,18 @@
from math import sqrt as _sqrt, acos as _acos, cos as _cos, sin as _sin
from os import urandom as _urandom
from _collections_abc import Set as _Set, Sequence as _Sequence
-from hashlib import sha512 as _sha512
from itertools import accumulate as _accumulate, repeat as _repeat
from bisect import bisect as _bisect
import os as _os
+try:
+ # hashlib is pretty heavy to load, try lean internal module first
+ from _sha512 import sha512 as _sha512
+except ImportError:
+ # fallback to official implementation
+ from hashlib import sha512 as _sha512
+
+
__all__ = ["Random","seed","random","uniform","randint","choice","sample",
"randrange","shuffle","normalvariate","lognormvariate",
"expovariate","vonmisesvariate","gammavariate","triangular",
diff --git a/Misc/NEWS.d/next/Library/2019-04-09-12-02-35.bpo-36559.LbDRrw.rst b/Misc/NEWS.d/next/Library/2019-04-09-12-02-35.bpo-36559.LbDRrw.rst
new file mode 100644
index 0000000..2f6ee78
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-04-09-12-02-35.bpo-36559.LbDRrw.rst
@@ -0,0 +1,2 @@
+The random module now prefers the lean internal _sha512 module over hashlib
+for seed(version=2) to optimize import time.