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On Sun, Oct 11, 2009 at 10:50 AM, Antoine Pitrou <solipsis@pitrou.net> wrote:

In py3k, the weak dict methods keys(), values() and items() have been
changed to return iterators (they returned lists in 2.x).
However, it turns out that it makes these methods quite fragile, because
a GC collection can occur whenever during iterating, destroy one of the
weakref'ed objects, and trigger a resizing of the underlying dict, which
in turn raises an exception ("RuntimeError: dictionary changed size
during iteration").

1. Add the safe methods listkeys(), listitems(), listvalues() which would

behave as the keys(), etc. methods from 2.x



2. Make it so that keys(), items(), values() atomically build a list of

items internally, which makes them more costly for large weak dicts, but

robust.