The forking issue is likely because you're using a connection pool and so once a connection is opened at config-time, even though the session is properly closed the connection is just returned to the pool. The pool here is shared across the fork which is bad. The basic solution here is to add some sort of pre-fork hook that closes out every existing connection in the pool. I personally have not used forking wsgi servers in production and thus have not needed to deal with this problem but I'm pretty sure my advice hits at the core issue you're experiencing. Calling dispose() is one way to make sure that the underlying connection is closed which is why it's working for you. If I recall, gunicorn has some way to fork before config is called such that each subprocess is loaded independently which can help with this as well... If memory serves it was something like turning off the preloading feature.
The explicit manager is about weeding out situations where you use a connection after it's closed [1]. Basically without it you could use something joined to the "tm" after the "with" block is done and you might not see an error. This is more likely to be an issue in web requests where your entire request lifecycle is not actually protected by a transaction. [1] https://docs.pylonsproject.org/projects/pyramid-tm/en/latest/#custom-transaction-managers On Mon, Apr 2, 2018 at 2:21 PM, Zsolt Ero <[email protected]> wrote: > Michael, I've updated the code to your recommendation. > > https://github.com/hyperknot/pyramid_connections_bug > > It still requires the explicit engine.dispose() line, otherwise it > does bring the connection to the forked processes. > > This is with and without the explicit manager. What does the explicit > manager protect us from? > > Zsolt > > > On 2 April 2018 at 20:11, Michael Merickel <[email protected]> wrote: > > Using the pyramid-cookiecutter-alchemy setup you can access config data > at > > config time using a pattern like this: > > > > from transaction import TransactionManager > > > > from myapp.models import get_tm_session > > > > def main(global_config, **settings): > > config = Configurator(settings=settings) > > config.include('myapp.models') > > > > tm = TransactionManager(explicit=True) > > with tm: > > dbsession = get_tm_session(config.registry['dbsession_factory'], > tm) > > ... # do queries and stuff > > > > return config.make_wsgi_app() > > > > This will properly handle the lifecycle of a session for you, same as > when > > serving a request. Be sure if you keep any objects around that you > expunge > > them from the session and re-attach/merge them into any session where you > > use them.. ORM objects are only valid on the dbsession they were loaded > > from. > > > > - Michael > > > > > > On Mon, Apr 2, 2018 at 11:59 AM, Zsolt Ero <[email protected]> wrote: > >> > >> OK, I agree with that. Still, storing config values in the database is > >> a common pattern for medium to large web apps, so it at least makes > >> sense to have some kind of resource about how to do it. I hope that if > >> nothing else at least this thread will be useful for someone in the > >> future. > >> > >> -- > >> You received this message because you are subscribed to the Google > Groups > >> "pylons-discuss" group. > >> To unsubscribe from this group and stop receiving emails from it, send > an > >> email to [email protected]. > >> To post to this group, send email to [email protected]. > >> To view this discussion on the web visit > >> https://groups.google.com/d/msgid/pylons-discuss/CAKw- > smBuH5hKGpNgs-6dYkNiAU%3DGGUUOF7aLHAzHe0AE25T7qg%40mail.gmail.com. > >> For more options, visit https://groups.google.com/d/optout. > > > > > > -- > > You received this message because you are subscribed to a topic in the > > Google Groups "pylons-discuss" group. > > To unsubscribe from this topic, visit > > https://groups.google.com/d/topic/pylons-discuss/_MJflNUcjdg/unsubscribe > . > > To unsubscribe from this group and all its topics, send an email to > > [email protected]. > > To post to this group, send email to [email protected]. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/pylons-discuss/ > CAKdhhwGoPbgM7gDWBLxdanT%3DhcJQR8sT01E2xwWFxw1zxpCD1A%40mail.gmail.com. > > > > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "pylons-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/pylons-discuss/CAKw-smBMmRqu2ZTPSp%3Djh% > 2BY0RriEwvxgdYQnwq--k4abeUkd-g%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "pylons-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/pylons-discuss/CAKdhhwGFjP7-aYzz4NEewWv1kdbMxhH25hrX4JC3oR4ZizqYeg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
