When does INSTALLED_APPS get imported on GAE if there is no warmup request?

Question

djangoappengine.views.warmup does its job of loading all Django apps when GAE sends a warmup request. If GAE does not send a warmup request, either due to request spike or because warmup service is not enabled, then when does INSTALLED_APPS get imported? I see that djangoappengine.deferred.handler.application loads all INSTALLED_APPS, but djangoappengine.main.application does not.

The problem I'm having is that if there is no warmup request, then either that first loading request handler or subsequent request handler may need a nonrel-search model field which is not yet registered, because search was not imported via INSTALLED_APPS and thus autodiscover() did not yet run.

My settings MIDDLEWARE_CLASSES does have 'autoload.middleware.AutoloadMiddleware', so I would think that it could load that way without warmup, but it's not.

What is the solution to make sure everything is loaded before handling any requests?

Answer 1

The solution is to call search.autodiscover() in the site's urls.py, in addition to having autoload and search in INSTALLED_APPS, as well as autoload.middleware.AutoloadMiddleware in MIDDLEWARE_CLASSES.

The reason is that while djangoappengine.views.warmup and djangoappengine.deferred.handler.application load INSTALLED_APPS and result in search.autodiscover() being called, djangoappengine.main.application does not does not do that. So if your GAE instance is fired up directly by a request, then the search indexes will not be registered. Therefore, search.autodiscover() in urls.py is necessary to register those indexes.