On 12/29/05, Raymond Hettinger
What could be done is to add a test for excess dummy entries and trigger a periodic resize operation. That would make the memory available for other parts of the currently running script and possibly available for the O/S.
The downside is slowing down a fine-grained operation like pop(). For dictionaries, this wasn't considered worth it. For sets, I made the same design decision. It wasn't an accident. I don't plan on changing that decision unless we find a body of real world code that would be better-off with more frequent re-sizing.
The computer scientist in me prefers O() terms over changes in a constant factor, but that's only me. Perhaps a note about it should be added to the documentation, though? Noam