[Python-Dev] reference leaks, del, and annotations (original) (raw)

Phillip J. Eby pje at telecommunity.com
Fri Mar 31 18:57:21 CEST 2006

At 11:27 PM 3/31/2006 +1000, Nick Coghlan wrote:

Generators are even more special, in that they only require finalisation in the first place if they're stopped on a yield statement inside a try-finally block.

Or a try-except block. Or a 'with' statement. It's only loop blocks that are exempt.

A simple Boolean attribute (e.g. finalized) should be enough. If the type has a del method, then the GC would check the finalized attribute. If it's both present and true, the GC can ignore the finaliser on that instance (i.e. never invokes it, and doesn't treat cycles as uncollectable because of it)

I don't know the GC well enough to know how hard that would be to implement, but I suspect we need to do it (or something like it) if PEP 342 isn't going to cause annoying memory leaks in real applications.

As Tim suggested, it'd be better to have the code be generator-specific, at least for now. That had actually been my original plan, to make it generator-specific, but I was afraid of breaking encapsulation in the garbage collector by having it know about generators. But now that Uncle Timmy has blessed the approach, I'll go back and add it in. (On Monday, unless somebody gets to it before me.)

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