[Python-Dev] new buffer in python2.7
solipsis at pitrou.net
Wed Oct 27 13:15:42 CEST 2010
> >Here are micro-benchmarks under 3.2:
> > $ ./python -m timeit -s "x = b'x'*10000" "x[:100]"
> > 10000000 loops, best of 3: 0.134 usec per loop
> > $ ./python -m timeit -s "x = memoryview(b'x'*10000)" "x[:100]"
> > 10000000 loops, best of 3: 0.151 usec per loop
> That's weird. The greedy slice needs two memory allocations. One for
> the ByteArray object itself, one for its cargo. In total, more that
> 100 bytes. In contrast, creating the MemoryView object requires only
> one allocation of a few dozen bytes.
It's not a bytearray object, it's a bytes object. It requires only a
single allocation since the data is allocated inline.
The memoryview object must also call getbuffer() again on the original
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