"We didn’t have any page caching in place at all."
Cache me if you can! If you're a high-traffic site and you are not caching static content (I recommend Varnish highly), then your are throwing money or good user experience out the window.
Cache me if you can! If you're a high-traffic site and you are not caching static content (I recommend Varnish highly), then your are throwing money or good user experience out the window.
I think in a growing site with a lot of custom per-user content (like a social network) the extra complexity of a cache layer and managing expiry is more pain than it's worth while iterating the product quickly. If you're mostly a content site, it's definitely the #1 thing you should be doing.
Realising that we're both at the same time, depending on the user or page, means that sometimes the cache stuff is the right thing to do, and sometimes not. I was leaning too far towards not, and happy now with the balance we've picked.
(We have a separate cookie that is present for signed-in users, so the fronted knows whether it should fire the annotation request.)
The result is that we can serve a sudden influx of unauthenticated users (e.g. from Google News or StumbleUpon) from nginx alone, which gives us massive scale from very little hardware. It's likely that the network is actually the bottleneck in this case, and not nginx.
An extra AJAX request grabs the users logged in status, CSRF token and similar data as JSON and then modifies the page so the user sees what they expect (a logout button, a comment form, etc).
https://github.com/orslumen/record-cache
If you're on Django I think cache-machine does the same thing. There are some things you won't get cached this way that you could manually (functions and procedures), but I think they're both conservative enough that you won't return stale resources.
One of the great things I love about Rails 3 is how easy it is to start caching. It can, and does, cause issues so make sure you're including caching in your test suite. I'm definitely looking forward to seeing how Rails 4 pushes this forward.
And I agree completely. Varnish is goddamn magical and a fascinating exercise in a principled approach to kernel-oriented memory management (a mindset I don't normally undertake).