[issue15381] Optimize BytesIO to so less reallocations when written, similarly to StringIO
Antoine Pitrou
report at bugs.python.org
Fri Jul 20 17:16:09 CEST 2012
Antoine Pitrou <pitrou at free.fr> added the comment:
Under Windows (64-bit Windows 7 on a VirtualBox VM), the patch increases performance slightly but not as much as under Linux:
-> before patch:
C:\t\cpython>pc\VS9.0\amd64\python.exe -m timeit -s "import io; n=2000; d=[b'a'*
n,b'bb'*n,b'ccc'*n]*1000" "s=io.BytesIO(); w=s.write" "for x in d: w(x)" "s.g
etvalue()"
10 loops, best of 3: 49.2 msec per loop
-> after patch:
C:\t\cpython>pc\VS9.0\amd64\python.exe -m timeit -s "import io; n=2000; d=[b'a'*
n,b'bb'*n,b'ccc'*n]*1000" "s=io.BytesIO(); w=s.write" "for x in d: w(x)" "s.g
etvalue()"
10 loops, best of 3: 41.7 msec per loop
And the join() approach is 10x faster (!):
C:\t\cpython>pc\VS9.0\amd64\python.exe -m timeit -s "import io; n=2000; d=[b'a'*
n,b'bb'*n,b'ccc'*n]*1000" "b''.join(d)"
100 loops, best of 3: 4.63 msec per loop
... which points to a much less optimized realloc() under Windows.
----------
_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue15381>
_______________________________________
More information about the Python-bugs-list
mailing list