[Zope-dev] ConnectionStateError

[Marius Gedminas]

On Wed, Jan 12, 2011 at 02:34:13PM +0100, Godefroid Chapelle wrote:
> We have been experiencing some ConnectionStateError in a Zope 2 based 
> application.
> 
> Looking for info on the web makes me almost 100% sure that we have a bug 
> in our application layer.
> 
> I understand that I should look for persistent objects stored in module 
> or class level variables (which imply shared by threads and thus 
> connections). Do not hesitate to tell me if this is a wrong explanation 
> of the potential cause of ConnectionStateError.
> 
> However, I wonder if some of you could give debugging techniques outside 
> reviewing the code.

I would be inclined to use pdb, get hold of the offending object, and
then use http://mg.pov.lt/objgraph/ to find which global variable refers
to it.

(It could be a case of "if all you've got is a hammer", since objgraph is
still shiny in my mind.)

> I also wonder what was the reason to deprecate ``zope.thread``.

Because it was folded into the standard library in Python 2.4.
zope.thread.local() became threading.local()

> I see it 
> was used by ``zope.component`` to hold thread-safe siteinfo. Could a too 
> frequent usage of getSite lead to ConnectionStateError ? I think that it 
> is not the case but I prefer to ask.

Unlikely.

Marius Gedminas
-- 
http://pov.lt/ -- Zope 3/BlueBream consulting and development
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