how to find out how much application memory django process is (or will be) taking?

Question

There are different "Application memory" options (like 80MB...200MB) in django-friendly hosting called webfaction and I'm confused deciding which one I should buy.

Could someone please walk me through the ideas on how to figure out how much memory my project might require (excluding operating system, the main apache server and the database servers memory requirements)? I understand in theory I'll need to perform some kind of load testing, but thought there might be ways to calculate that in advance with some simple/relatively easy understandable approach.

I don't know how hard they enforce application memory usage limit, and another question is: what will happen if more users came to the site and more threads started than what I expected? Will the application crash? Or will delays just become uncomfortable?

And - no, application is not ready yet (I can't measure anything right now). Development environment if it matters is Winodows 7, 64-bit. Hosting itself is some kind of Linux I think.

(Sorry if it's not a stackoverflow question.)

Answer 1

Sorry, but until you have the application completely developed, you can't say anything about the kind of memory it'll use. I recommend that you take their "lowest" plan, and renew to it to fit your needs, or still better: get hosting after you finish developing the application.

On the other hand, if you had the application ready, you could just run it in Apache with your host's config and some sample data to get a rough estimate...

Answer 2

I agree that you can' tell much before your app is ready. As a vague estimation consider that your host is supposed to be "django-friendly" so some "basic" application should run without problems. Try and upgrade later if that's possible easily. Also consider the type of data that is processed with your app, I eg. ran into troubles once when I had to process really large image uploads that made the whole site crash.
Also keep in mind if you need some ram for additional processes eg. memcache!

Answer 3

Webfaction are indeed a Django-friendly host, and your application will certainly not crash if it starts needing more memory than you have paid for. What will happen is that you will be allowed to use small amounts of extra memory, but if you consistently go over the limit they will send you a polite email requesting that you either reduce the load or pay for more.