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[Python-Dev] Py_CLEAR to avoid crashes

Jeffrey Yasskin jyasskin at gmail.com
Sun Feb 17 19:14:29 CET 2008 
On Feb 16, 2008 3:12 PM, Amaury Forgeot d'Arc <amauryfa at gmail.com> wrote:
> Should we however intensively search and correct all of them?
> Is there a clever way to prevent these problems globally, for example
> by delaying finalizers "just a little"?

A simple way to do this would be to push objects whose refcounts had
reached 0 onto a list instead of finalizing them immediately, and have
PyEval_EvalFrameEx periodically swap in a new to-delete list and
delete the objects on the old one. A linked list would cost an extra
pointer in PyObject_HEAD, but a growable array would only cost
allocations, which would be amortized over the allocations of the
objects you're deleting, so that's probably the way to go. A
fixed-size queue that just delayed finalization by a constant number
of objects would usually work without any allocations, but there would
sometimes be single finalizers that recursively freed too many other
objects, which would defeat the delay.

Jeffrey
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