[Python-Dev] iterzip()

[Guido van Rossum]

> A fixed threshold of any size will leave us vulnerable to
> quadratic-time cases.  Proportional growth wouldn't, though.  For
> example, if a round of gc didn't find anything to collect, or found
> very little, we could boost the threshold by 25% (that's a right
> shift by 2 and an add <wink>).  Contrarily, when gc finds lots of
> stuff to collect, reduce the threshold.  This adjusts itself to a
> program's runtime characteristics.  I suspect most long-running
> programs enjoy vast stretches of time over which the second
> derivative of their gc behavior is relatively constant <wink>.

Should we worry about programs that don't create any cyclical garbage
for a long time, and then sudenly start creating lots of it?  The
initial GC-free period may bump the threshold up very far, and then it
will build up a significant pile of cyclical garbage before GC runs
again.

--Guido van Rossum (home page: http://www.python.org/~guido/)