[Python-Dev] Dealing with import lock deadlock in Import Hooks (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Tue Aug 13 08:50:00 CEST 2013

On Tue, 13 Aug 2013 11:06:51 +0900 Arnaud Fontaine <arnaud.fontaine at nexedi.com> wrote:

Hi,

Armin Rigo <arigo at tunes.org> writes: > On Mon, Aug 12, 2013 at 9:39 AM, Arnaud Fontaine <arnaud.fontaine at nexedi.com> wrote: >> Thread 1 is trying to import a module 'foo.bar' (where 'foo' is a >> package containing dynamic modules) handled by Import Hooks I >> implemented, so import lock is acquired before even running the hooks >> (Python/import.c:PyImportImportModuleLevel()). Then, these import >> hooks try to load objects from ZODB and a request is sent and handled >> by another thread (Thread 2) which itself tries to import another >> module. > > A quick hack might be to call imp.releaselock() and > imp.acquirelock() explicitly, from your import hook code, around > calls to ZODB. I suggested the same in my initial email, but I was wondering if there could be any issue by releasing the lock in findmodule()/loadmodule() until the module is actually added to sys.modules.

Well, you are obviously on your own with such hacks. There is a reason the lock exists.

Regards

Antoine.

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