Caching the current Site object into cache backend

[astafiev.anton@…]

As it is described ​here current site object is cached.

I was very surprised, when it turned out, that this object is cached into sites.models.SITE_CACHE dictionary
I think, that Django should use the same cache engine everywhere. Caching into global objects could produce problems that are very hard to diagnose. Also, it is much easier to have only one interface to flush the cache.

I propose to use standard cache interface here. I could provide the patch, if you think it is reasonable.

[Aymeric Augustin]

Not everyone has a cache configured.

[Russell Keith-Magee]

As Aymeric points out, there's no guarantee that a cache backend is available.

The real problem here is that there is global state -- and while I'll agree that this is a problem, it's not a problem we fix by moving to a different store to hold that global state.

I'm going to mark this wontfix. I'll completely agree that it would be a good idea to remove the global state; however, this is really a small part of a much bigger architectural problem.

[Karen Tracey]

This should more properly be closed as a dupe of #15894. Nobody there has yet objected that not everyone has a cache configured. This is so extremely broken in a multiprocess environment that it deserves fixing, in my opinion.