Re: [Chicken-users] String compression?

[felix winkelmann]

On 12/21/06, Graham Fawcett <address@hidden> wrote:
> Hi folks,
>
> Does anyone have code for compressing strings using zlib, lzo or some
> other common llibrary/algorithm? I seem to have z3 working, but the
> performance is really terrible -- I may be doing something wrong, to
> be fair, the documentation is a bit light.
>
> I'm getting ~20x better performance using (process "gzip") to fork
> gzip and compress that way, compared with a string-compression
> procedure that I copied from the z3 test-script:
>
> [...]
>
> I know it's not an apples-to-apples comparison. But why the huge
> difference? My lack of understanding of the z3 egg may be the cause.

Your code looks ok. Note the massive number of (major) garbage
collections. The code just conses a lot. One reason for that is the
repeated (and required) use of substring. The z3lib itself should be
fast enough, but it may be that the interface is too simplistic. I
will add a set of compress/decompress-the-whole-buffer routines written
in C which should be much faster.


cheers,
felix