New submission from Antoine Pitrou: If you delete a slice at the end of a bytearray, it is naturally optimized (thanks to the resizing strategy). However, if you delete a slice at the front of a bytearray, it is not: a memmove() gets done every time.
$ ./python -m timeit "b=bytearray(10000)" "while b: b[-1:] = b''" 100 loops, best of 3: 5.67 msec per loop $ ./python -m timeit "b=bytearray(10000)" "while b: b[:1] = b''" 100 loops, best of 3: 6.67 msec per loop $ ./python -m timeit "b=bytearray(50000)" "while b: b[-1:] = b''" 10 loops, best of 3: 28.3 msec per loop $ ./python -m timeit "b=bytearray(50000)" "while b: b[:1] = b''" 10 loops, best of 3: 61.1 msec per loop $ ./python -m timeit "b=bytearray(100000)" "while b: b[-1:] = b''" 10 loops, best of 3: 59.4 msec per loop $ ./python -m timeit "b=bytearray(100000)" "while b: b[:1] = b''" 10 loops, best of 3: 198 msec per loop This makes implementing a fifo using bytearray a bit suboptimal. It shouldn't be very hard to improve. ---------- components: Interpreter Core messages: 198385 nosy: pitrou priority: normal severity: normal stage: needs patch status: open title: bytearray front-slicing not optimized type: performance versions: Python 3.4 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue19087> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
