[Python-Dev] Optimization targets - refcount (original) (raw)

Mike Pall mikepy-0404 at mike.de
Sat Apr 17 17:50:00 EDT 2004

Hi,

Aahz wrote:

On Fri, Apr 16, 2004, Mike Pall wrote: > To summarize: I think we can optimize the GC a little more (have not done > an in-depth analysis yet), but we really should focus on making Python > less malloc-happy. Suggestions welcome!

Could you expand on this? What do you mean by "less malloc-happy"? What you were talking about earlier was None, which doesn't go through malloc hoops. I think you might find it useful to at least read old threads about refcounting vs. GC. (I managed to dig up the old thread about getting rid of refcounting for None; don't have time for more.)

I'm very well aware of the tradeoffs between refcounting and pure GC schemes. I do not suggest that we change CPython's approach. And I do not intend to start another refcount-vs-GC flamewar. You've got me wrong.

Also please check the thread -- I never suggested modifying anything about Py_None. I just presented a short quantitative analysis that it's useless to do so (the thread you referenced contains another good reason).

What I meant with 'less malloc-happy' is that we should try to reduce the number of allocations/deallocations for internal (!) objects (I'm not talking about objects explicitly managed by the application). Many of them have a very short time-to-live. I guess some of them could be recycled or even optimized away.

E.g. global profiling indicates that tuple allocation/deallocation has a noticeable effect on performance. There are probably other objects that have prohibitive setup/teardown cost (but are less pronounced on allocation costs).

But since this is only #4 on my list I have not given it a closer look. That's why I said 'suggestions welcome'.

Bye, Mike

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