#11331: Memcached backend closes connection after every request ------------------------------+--------------------------------------------- Reporter: boo...@gmail.com | Owner: nobody Status: new | Milestone: Component: Cache system | Version: 1.0 Keywords: | Stage: Unreviewed Has_patch: 0 | ------------------------------+--------------------------------------------- Fix for http://code.djangoproject.com/ticket/5133 kills servers in production.
-- Copy of http://code.djangoproject.com/ticket/5133#comment:16 The patch takes care of connections kept open, but it introduces another problem - the need to open one or more tcp connections every single request. With a simple loop, you can make a system run out of sockets easily - after a socket is closed, that port cannot be reused for an eternity, ranging from 1 minute to 4 depending on OS. If enough sockets get stuck in TIME_WAIT state, the server simply fails to connect to memcached and start serving everything from db again - that's not something you want to see on a site with sufficient traffic to need a memcached installation. In my opinion, the cure is worse than the disease. There's an easy workaround available for the original problem: restart workers after a certain amount of requests. With max-request=500 on a 5 threads deamon process (mod_wsgi, times 20 processes), we never go over 100 connections on our memcached server, started with the default cap of 1024 connections. If you run mod_python, use MaxRequestsPerChild?. My current solution is to just noop the whole fix with one line in any .py: django.core.cache.backends.memcached.CacheClass?.close = lambda x: None. It might be an idea to make it configurable so people can choose between disconnect after every request and keep it open until process restart. -- Ticket URL: <http://code.djangoproject.com/ticket/11331> Django <http://code.djangoproject.com/> The Web framework for perfectionists with deadlines. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django updates" group. To post to this group, send email to django-updates@googlegroups.com To unsubscribe from this group, send email to django-updates+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-updates?hl=en -~----------~----~----~----~------~----~------~--~---
