[issue28731] _PyDict_NewPresized() creates too small dict
INADA Naoki
report at bugs.python.org
Fri Nov 18 06:08:28 EST 2016
INADA Naoki added the comment:
This patch includes fix for ESTIMATE_SIZE macro. (see below)
Same fix is included in patch for issue28147.
>>> def estimate_size(n):
... return n * 3 // 2 # Current ESTIMATE_SIZE
...
>>> def usable(n):
... return n * 2 // 3
...
>>> def keysize(minsize):
... size = 8
... while size < minsize: # Current implementation uses <=
... size *= 2
... return size
...
>>> def check():
... for i in range(1000):
... estimate = estimate_size(i)
... size = keysize(estimate)
... cap = usable(size)
... if cap < i:
... print(i, estimate, size, cap)
...
>>> check()
11 16 16 10
43 64 64 42
171 256 256 170
683 1024 1024 682
>>> #
>>> estimate_size = lambda n: (n * 3 +1) // 2 # Fixed version
>>> check()
>>>
----------
_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue28731>
_______________________________________
More information about the Python-bugs-list
mailing list