[Python-Dev] Revised 1.6 jobs list

[Neil Schemenauer]

On Mon, Jun 05, 2000 at 12:43:45AM -0400, Jeremy Hylton wrote:
> [Entry from AMK's 1.6 jobs list:]
> > Conservative garbage collection of cycles (maybe -- I don't know what GvR
> >         thinks about this)
> 
> I believe Guido would like to see a version of Neil's patches
> integrated into Python 1.6, most likely turned off by default but with
> a configure flag to enable.

Okay, I was thinking he had passed it over for 1.6 since I didn't
hear any comments from him for a long time.

> I would like to check the patch in soon but I have had some trouble
> with segfaults.  I ran a simple benchmark using the compiler code in
> the nondist tree to compile itself.  I get a crash during a routine
> collect pass, where it looks like the GC header info is getting
> trashed.  I haven't had much time to track it any farther.

Yow.  I will try to see if I can reproduce this.  What platform?

> If anyone else is interested, I'd love to hear about successes using
> the GC patch with other large programs.  I'd like to run at least
> Gadfly and Grail successfully before committing the patch.

I've used it with Grail, Sketch, IDLE as well as some of my own
software.  I may have introduced that SEGV bug when porting the
patch to a newer version of the CVS sources.  I will check it
out.

> I also worry that the performance impact of the GC patch is not
> at all understood.

Me too.

> I don't know what informed the choice of heuristics for
> deciding how often to collect and how to move objects between
> generations. (The current scheme has three generations.) It
> would be good to get a working patch in before the next alpha
> release and then gather a lot of data to help make good choices
> about these parameters.

Getting good performance will be a matter of tuning how often the
collector runs.  I don't think there is any substitute for
running real programs and collecting data.  Programs that
allocate lots of objects will be most interesting.  It would
probably be a good idea to add more support for keeping
collection statistics.  Unfortunately my time is very limited
right now.

> PS Even if Guido doesn't think the GC patch should go in, we've got a
> golden opportunity.  I caught him in a state of newly-wedded bliss
> this morning and convinced him to let me check in my non-optional
> braces patch while he's on his honeymoon.  He's so happy he'll let us
> get away with anything.

I wonder if he will be scowling less at the conferences now that
he is hitched. :)

    Neil