[Python-Dev] iterzip() (original) (raw)

Tim Peters tim.one@comcast.net
Mon, 29 Apr 2002 19:36:10 -0400

[Barry]

Isn't this a case of "knowing your application"? IOW, you're doing something that the gc isn't well-tuned to handle, by default. That's why we expose the its operation through the gc module -- so you can take explicit steps for the hotspots in your application.

The difficulty is with apps that grow a lot of long-lived containers that aren't trash and don't even contain cycles. There's no bound on how often they'll get crawled over looking for trash that ain't there, and the more of those you grow the longer it takes to look at them. When a gen2 collection doesn't find any trash, it should probably become less eager to try looking at the same stuff yet again. Adding more generations could have a similar good effect.

Half of a shadow of an idea: at least in my code, it's common to have gazillions of tuples, and they almost always contain just strings and numbers. Since they're immutable, they'll never contain anything else. So they could get unlinked from cyclic gc entirely without ill effect (it's not possible that they could ever be in a cycle). Perhaps a gen2 collection could learn something about this and automagically untrack them.