[Python-Dev] Using PEP384 Stable ABI for the lzma extension module (original) (raw)

Toshio Kuratomi a.badger at gmail.com
Wed Oct 5 18:38:10 CEST 2011

On Wed, Oct 05, 2011 at 06:14:08PM +0200, Antoine Pitrou wrote:

Le mercredi 05 octobre 2011 à 18:12 +0200, "Martin v. Löwis" a écrit : > >> Not sure what you are using it for. If you need to extend the buffer > >> in case it is too small, there is absolutely no way this could work > >> without copies in the general case because of how computers use > >> address space. Even PyBytesResize will copy the data. > > > > That's not a given. Depending on the memory allocator, a copy can be > > avoided. That's why the "str += str" hack is much more efficient under > > Linux than Windows, AFAIK. > > Even Linux will have to copy a block on realloc in certain cases, no?

Probably so. How often is totally unknown to me :) http://www.gnu.org/software/libc/manual/html_node/Changing-Block-Size.html

It depends on whether there's enough free memory after the buffer you currently have allocated. I suppose that this becomes a question of what people consider "the general case" :-)

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