Simon Willison’s Weblog

How scalable is Django?

21st August 2013

My answer to How scalable is Django? on Quora

Django scales in exactly the same way as PHP or Rails or any other stateless shared-nothing web technology: you ensure that the web nodes (running your Django code) are independent from your persistence layer (database, caching, session storage etc) and scale then independently.

Since the Django web nodes have no stored state, they scale horizontally—just fire up more of then when you need them. Being able to do this is the essence of good scalability.

In my experience Java applications are more likely than Python applications to have stateful web servers which fail to scale horizontally, hence the more common need for things like load balances that support sticky sessions in the Java world.

That’s not to say you can’t have stateless Java web application servers that scale horizontally if you set out to do so—you just need to be disciplined about it.

Performance is another matter entirely: Java is generally faster than Python, and some aspects of Django (such as the template language) are actually quite slow. But performance and scalability are not the same thing.