On Dec 22, 9:01 am, Chris Curvey <ccur...@gmail.com> wrote: > The short version: when processing a request, does Django *always* > collect session information from the session store before starting the > view? >
Yes. However note that django only saves to the session database when the session has been modified. It doesn't seem like that's affecting you, but I can't be sure. http://www.djangobook.com/en/2.0/chapter14/ > The long version: > > i have an application that makes heavy use of AJAX. When a user > changes something on the page, the page fires an AJAX POST to apply > the changes to the database, then a series of AJAX GETs to refresh > other portions of the page. > You say, "then a series of AJAX GETs" but when is "then"? Presumably in the post's callback function? Because otherwise you have no guarantee that the POST completes before the GETs fire. > Some of the GETs are expensive, so I have some process_response() > middleware that caches the HTML generated by the GET in the Django > session. (It's the standard database session store.) I also have > some process_request() middleware that either returns the cached HTML > if it can, or invalidates the cache on any POST. > > Just to add to the fun, I have a four identical Django/mod_wsgi > instances running behind a round-robin load balancer. So the POST > request might get handled by Django1, the first GET by Django2, the > second GET by Django3, and so on. > > My problem is that sometimes the results of the POST are not visible > in the results of the GET. The problem is intermittent, which is > leading me to point the finger at my cacheing strategy. My assumption > was that Django would reload the session from the database every time > before starting my view code, but I'm wondering if that is not true > (or if there is some other issue that I'm not thinking about). Yes, your caching seems a likely culprit, and so does the asynchronous nature of you AJAX (but it seems like you've got a handle on that part). I haven't thought through the load balancer bit yet, but presumably they are all using the same cache / database / session store..? --Stuart -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
