[Python-Dev] Linus on garbage collection

[Antoine Pitrou]

On Fri, 06 May 2011 15:46:08 +0100
Mark Shannon <marks at dcs.gla.ac.uk> wrote:
> 
> Neal Becker wrote:
> > http://gcc.gnu.org/ml/gcc/2002-08/msg00552.html
> > 
> Being famous does not necessarily make you right.
> 
> OS kernels are pretty atypical software,
> even if Linus is right about Linux, it doesn't apply to Python.
> 
> I have empirical evidence, not opinion, that PyPy and my own HotPy
> are a *lot* faster (x5 or better) on Unladen Swallow's gcbench benchmark 
> (which stresses the memory management subsystem).
> 
> (Note that gcbench does not introduce any cycles, so its being easy on 
> CPython)
> 
> In fact, for gcbench CPython spends over twice as long in the 
> cycle-collector as HotPy takes in total!

The thing is, it would be easy to change our collection heuristics
so that the cycle collector gets called less often (actually, you can
already do so using gc.set_threshold, IIRC). Something which is much
more delicate for a "full" GC, where it would grow memory consumption a
lot.

Regards

Antoine.