Django使用Apache2（mod_wsgi）的问题，有时无明显原因“无法从模块导入”

Question

I have put my Django web site up to my web server and have it set up using apache2 and mod_wsgi.. everything works fine most of the time but occasionally it will just give the error that it can't import a module (usually from my views file). However, it's not an issue with that module as it usually works, for example, I will get the error "Cannot import classname from module" once, then reload the page and it works fine, I would say it's about 1 in 10 page loads where this occurs and it's just random as it will happen for any page on my site.

I have tried restarting apache2, restarting the server but the issue persists. I have tried it on different client machines, clearing out the user cache, etc but the issue persists. I don't know what might be doing this, would perhaps some sort of caching help prevent this as it seems that the server is just having an issue with sometimes not being able to fully process the request. I am using a cloud set up with not much memory on the server so maybe this is the problem? Any advice is appreciated

Answer 1

It is working most of the time because you likely have a multi process configuration and only one of the processes is affected.

You can try alternate WSGI script file as documented in:

http://blog.dscpl.com.au/2010/03/improved-wsgi-script-for-use-with.html

The jury is still out as to whether the issue is the differences between development server and proper deployment systems using WSGI, or whether it is users not handling imports properly and causing order dependencies or even import cycles. Problems possibly only come up when URL visited in certain order and thus why random as to when it can happen.