Fatal Python error: deallocating None

[Gabriel Genellina]

At Wednesday 25/10/2006 21:28, George Sakkis wrote:

>It's the first time in the three years I've been using python that a
>program crashes without a nice traceback to give me a clue of what
>might be wrong. After searching a little, it seems it's one of those
>hard to get down to cases, so I've no idea where to look for. Briefly
>what I do is, select some rows from one table, do some number crunching
>and insert or update rows in another table. The C extensions I'm using
>are numarray and MySQLdb (indirectly, through Sqlalchemy).
>
>What makes the problem worse is that it's not deterministic; I can
>restart it from (a little before) the point of crash and it doesn't
>happen again at the same point, but it might happen further down. Now,
>I wouldn't mind restarting it manually every time since the crashes are
>not all that frequent; problem is, it's supposed to be a long-running
>process that will probably take days to finish normally, so I want it
>to run overnight too. Any hints ?

Mmm, it appears that one of these C extensions isn't managing the ref 
count correctly - perhaps there is a return Py_None without a 
previous Py_INCREF? If None were returned in certain functions to 
indicate failure or something exceptional - and not a regular 
condition - that would explain that it doesn't fail very often.
Unfortunately I don't know how to debug this - except by carefully 
inspecting the C code :(


-- 
Gabriel Genellina
Softlab SRL 

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