Hi Nils, On 2012-09-06, Nils Bruin <nbr...@sfu.ca> wrote: > We've seen before that invalidated expect interfaces can interact > unexpectedly with weakreffed stuff in entirely unrelated places.
grep weak -R sage/interfaces told me: sage/interfaces/expect.py: quit.expect_objects.append(weakref.ref(self)) and sage/interfaces/mwrank.py: instances[options] = weakref.ref(X) So, weak references *are* involved. I wonder why the pexpect interfaces are referred in a weak way. A potential debugging approach is now: Add a callback to the weak reference that prints a message when a pexpect interface gets collected. In that way, I should see whether a premature collection occurs. Could there be a race condition? Like this: Some interface E is deleted, so, E.__del__() is called, which involves E.quit(). If I am not mistaken (correct me if I'm wrong), the weak reference to E is still valid until E.__del__() has finished. The racing condition is: *During* execution of E.quit() inside E.__del__(), it could happen that sage.interfaces.quit.invalidate_all() is called. Since the weak reference to E is still valid, another call to E.quit() would occur *before* the first call to E.quit() is done. And nested pexpect call will lock the interface. Cheers, Simon -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To post to this group, send email to sage-devel@googlegroups.com. To unsubscribe from this group, send email to sage-devel+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel?hl=en.
