Where'd my memory go? (was Re: [Python-Dev] Dictionary sparseness)

[M.-A. Lemburg]

Tim Peters wrote:
> [Skip Montanaro]
> 
> [on assorted freelists]
> 
>>These shortcomings could be remedied by suitable inspection
>>functions added to sys for debug builds.
> 
> If someone cares enough <wink>, sure.
> 
>>This leads me to wonder, has anyone measured the cost of deleting the
>>int and float free lists when pymalloc is enabled?  I wonder how
>>unbearable it would be.
> 
> Vladimir did when he was first developing pymalloc, and left the free lists
> in deliberately.  I haven't tried it.  pymalloc is a bit faster since then,
> but will always have the additional overhead of needing to figure out
> *which* freelist to look in (pymalloc's free lists are segregated by block
> size), and, because it recycles empty pools among different block sizes too,
> the overhead on free of checking for pool emptiness.  The int free list is
> faster in part because it's so damn Narcissistic <0.7 wink>.

If someone really care, I suppose that the garbage collector could
do an occasional scan of the int free list and chop of the tail
after a certain number of entries.

FWIW, Unicode free lists have a cap to limit the number of entries
in the list to 1024.

-- 
Marc-Andre Lemburg
eGenix.com

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