How to improve performance of multiple rails applications with nginx running on a single core 378mb VPS?

Question

I have a VPS which is hosting (currently) 5 different rails applications, all with different domains. To make them work I've added one server {} listener per app in my nginx config file. I've left everything else as default, for instance there's only one nginx worker process. Concurrently, I also have 2 rails workers for one of the apps.

Now, this works as is, but performances are low, in particular speed. How could I make my apps quicker by adhering to my constraints?

Thanks!

Answer 1

The nginx "worker_processes" should be set to the number of cores that you have available to work with. You mentioned you had it set to 1. Do you have more cores than that?

Answer 2

Your problem is that you are deep into swap. The slowness you experiencing switching apps is the system loading the requested app from swap into physical memory.

To address this, you can observe who is hogging the memory (also using 'top'), and address that. It's possible you'll find some things to tune, but also quite possible you'll find that you are near the physical limits of what's possible without significant architectural changes.

If your time is worth much, your best course of action will be to upgrade to an instance with at least a 1GB of memory, because you are already using nearly that much.