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

M.-A. Lemburg mal@lemburg.com
Tue, 06 May 2003 12:03:15 +0200

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 , 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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