[Python-bugs-list] [ python-Bugs-485781 ] get_refer{ent,rer}s() doesn't use `is'

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Bugs item #485781, was opened at 2001-11-26 13:16
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Category: Python Interpreter Core
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 7
Submitted By: Zooko Ozoko (zooko)
Assigned to: Martin v. Löwis (loewis)
Summary: get_refer{ent,rer}s() doesn't use `is'

Initial Comment:
in Python 2.2b2 as packaged by debian,
gc.get_referents() seems to be using equality testing
rather than identity testing to find referents.  Example:

>>> l = [0,3,2,{},]
>>> gc.get_referents({})
[Type help() for interactive help, or help(object) for
help about object., [0, 3, 2, {}]]


The list should not have appeared in the result.



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>Comment By: Martin v. Löwis (loewis)
Date: 2001-11-29 10:14

Message:
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The patch has been committed as gcmodule.c 2.31. Since it
fixes *this* bug (about using ==), I'll close this report.

As for the problem you are still seeing: It would be good if
the segfault could be analysed in a debugger (using the old
core file if you cannot reproduce it in a life debugger).

I have the suspicion that this is a different problem:
refs.remove will also use ==, not is. That still shouldn't
cause a segfault, but it appears to be a different bug. If
you have further details, don't hesitate to open a new bug
report.

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Comment By: Zooko Ozoko (zooko)
Date: 2001-11-28 07:52

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Whoops, although it survived an overnight run of
continuously doing `get_referrers({})' (which formerly would
have triggered a seg fault), it did not survive the
following interactive code:

>>> for ref in refs[:]:
...  for k, v in locals().items():
...   if (ref is k) or (ref is v):
...    refs.remove(ref)
...

That got a segfault.  `refs' was a list of objects (namely,
all objects in the current runtime that held a reference to
an empty dict.


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Comment By: Zooko Ozoko (zooko)
Date: 2001-11-28 06:39

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Yep!  That patch fixes the problem with getting answers I
didn't want *and* it fixes the seg faults!

Now I'm making faster progress on diagnosing memory usage in
Mojo Nation.  Whoo-hoo!



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Comment By: Martin v. Löwis (loewis)
Date: 2001-11-26 23:22

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Please try the attached patch (or report back if you cannot).

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