[PyGreSQL] [patch] relinquish GIL while connecting to database

[Peter Schuller]

Hello,

I discovered recently that connection attempts hang the Python
interpreter for the duration of them. This is undesirable for various
reasons.

Attached is a patch that inserts Py_BEGIN_ALLOW_THREADS /
Py_END_ALLOW_THREADS before/after the connection attempts.

As far as I can tell, there is nothing being done that would cause a
problem by doing this (in terms of relying on global state in a
non-readonly fashion or similar). It would be interesting to know if
anyone knows the history here; whether the lack of relinquishing is an
oversight or something that was done on purpose.

I'm also attaching a small test-case that doesn't do much but launch
some threads to repeatedly connect/disconnect, which I used to get
some more confidence in the change (it runs at full speed until given
a KeyboardInterrupt).

The patch and test case are also available here:

   http://distfiles.scode.org/mlref/patch-pgmodule.c
   http://distfiles.scode.org/mlref/pgdbconntest.py

Any thoughts?

NOTE: The patch is against version 3.8.1 as I was unable to find a
working method of accessing the CVS repository. The cvsweb interface
is down, and I didn't find information on the location of the
repository itself.

-- 
/ Peter Schuller

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