zopefoundation / zope.interface / 42127800777

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master: 99%

Pull #398

github

Fix the race in the lazy declarations import

Two threads could both see ``decl_imported`` unset, both load the
declarations, and the second one overwrote the module state, leaking
the first set of references.  This also happens on GIL builds, since
the import and the attribute lookups can release the GIL.  On
free-threaded builds the flag was additionally read and written
without ordering, so a reader could see it set before the fields.

Keep loading without a lock, but publish the result in a critical
section: the first thread stores its references, a later one drops
its own.  Read the flag with acquire and set it with release ordering
on free-threaded builds.

Fixes #391.

Assisted-by: Claude Opus 5.5

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