[Python-Dev] cpython: Issue #22003: When initialized from a bytes object, io.BytesIO() now (original) (raw)

Serhiy Storchaka storchaka at gmail.com
Wed Jul 30 08:11:24 CEST 2014

30.07.14 06:59, Serhiy Storchaka написав(ла):

30.07.14 02:45, antoine.pitrou написав(ла):

http://hg.python.org/cpython/rev/79a5fbe2c78f changeset: 91935:79a5fbe2c78f parent: 91933:fbd104359ef8 user: Antoine Pitrou <solipsis at pitrou.net> date: Tue Jul 29 19:41:11 2014 -0400 summary: Issue #22003: When initialized from a bytes object, io.BytesIO() now defers making a copy until it is mutated, improving performance and memory use on some use cases.

Patch by David Wilson. Did you compare this with issue #15381 [1]? [1] http://bugs.python.org/issue15381

Using microbenchmark from issue22003:

$ cat i.py import io word = b'word' line = (word * int(79/len(word))) + b'\n' ar = line * int((4 * 1048576) / len(line)) def readlines(): return len(list(io.BytesIO(ar))) print('lines: %s' % (readlines(),)) $ ./python -m timeit -s 'import i' 'i.readlines()'

Before patch: 10 loops, best of 3: 46.9 msec per loop After issue22003 patch: 10 loops, best of 3: 36.4 msec per loop After issue15381 patch: 10 loops, best of 3: 27.6 msec per loop

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