[Python-Dev] PyWeakref_GetObject() borrows its reference from... whom? (original) (raw)

Guido van Rossum guido at python.org
Mon Oct 10 12:37:44 EDT 2016

Modified +1: you can't change the behavior of the existing API, but you can deprecate it and introduce a better one with a different name. We'll have until Python 4.0 to carry through the deprecation anyways. And I doubt this is the only C API change needed for happy gil-free coding...

On Mon, Oct 10, 2016 at 5:29 AM, Fred Drake <fred at fdrake.net> wrote:

On Mon, Oct 10, 2016 at 4:17 AM, Larry Hastings <larry at hastings.org> wrote:

Given that the weakref doesn't have a reference to the object--merely a weak reference, different thing--whose reference is it borrowing? As others have said, it doesn't really matter who's reference it was; just that there was another at the time it was returned. Clearly it can't be considered valid once additional Python code might be run.

FWIW, yes, this is playing merry hell with the Gilectomy. If there are two threads, and one calls PyWeakrefGetObject(obj), and there's only one reference to obj, and the other thread blows it away... now what? It's my contention that this API is simply untenable under the Gilectomy, and that it needs to change to returning a new (strong) reference. +1 for this change. -Fred -- Fred L. Drake, Jr. "A storm broke loose in my mind." --Albert Einstein

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