Does Django scale? [closed]
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 3 years ago. I'm building a web application with Django. The reasons I chose Django were: I wanted to work with free/open-source tools. I like Python and feel it's a long-term language, whereas regarding Ruby I wasn't sure, and PHP seemed like a huge hassle to learn. I'm building a prototype for an idea and wasn't thinking too much about the future. Development speed was the main factor, and I already knew Python. I knew the migration to Google App Engine would be easier should I choose to do so in the future. I heard Django was "nice". Now that I'm getting closer to thinking about publishing my work, I start being concerned about scale. The only information I found about the scaling capabilities of Django is provided by the Django team (I'm not saying anything to disregard them, but this is clearly not objective information...). My questions: What's the "largest" site that's built on Django today? (I measure size mostly by user traffic) Can Django deal with 100,000 users daily, each visiting the site for a couple of hours? Could a site like Stack Overflow run on Django?
“What are the largest sites built on Django today?”
There isn’t any single place that collects information about traffic on Django built sites, so I’ll have to take a stab at it using data from various locations. First, we have a list of Django sites on the front page of the main Django project page and then a list of Django built sites at djangosites.org. Going through the lists and picking some that I know have decent traffic we see:
pownce.com (no longer active): alexa rank about 65k.
Mike Malone of Pownce, in his EuroDjangoCon presentation on Scaling Django Web Apps says “hundreds of hits per second”. This is a very good presentation on how to scale Django, and makes some good points including (current) shortcomings in Django scalability.
HP had a site built with Django 1.5: ePrint center. However, as for novemer/2015 the entire website was migrated and this link is just a redirect. This website was a world-wide service attending subscription to Instant Ink and related services HP offered (*).
“Can Django deal with 100,000 users daily, each visiting the site for a couple of hours?”
Yes, see above.
“Could a site like Stack Overflow run on Django?”
My gut feeling is yes but, as others answered and Mike Malone mentions in his presentation, database design is critical. Strong proof might also be found at www.cnprog.com if we can find any reliable traffic stats. Anyway, it’s not just something that will happen by throwing together a bunch of Django models 🙂
There are, of course, many more sites and bloggers of interest, but I have got to stop somewhere!
Blog post about Using Django to build high-traffic site michaelmoore.com described as a top 10,000 website. Quantcast stats and compete.com stats.
(*) The author of the edit, including such reference, used to work as outsourced developer in that project.
We’re doing load testing now. We think we can support 240 concurrent requests (a sustained rate of 120 hits per second 24×7) without any significant degradation in the server performance. That would be 432,000 hits per hour. Response times aren’t small (our transactions are large) but there’s no degradation from our baseline performance as the load increases.
We’re using Apache front-ending Django and MySQL. The OS is Red Hat Enterprise Linux (RHEL). 64-bit. We use mod_wsgi in daemon mode for Django. We’ve done no cache or database optimization other than to accept the defaults.
We’re all in one VM on a 64-bit Dell with (I think) 32Gb RAM.
Since performance is almost the same for 20 or 200 concurrent users, we don’t need to spend huge amounts of time “tweaking”. Instead we simply need to keep our base performance up through ordinary SSL performance improvements, ordinary database design and implementation (indexing, etc.), ordinary firewall performance improvements, etc.
What we do measure is our load test laptops struggling under the insane workload of 15 processes running 16 concurrent threads of requests.
Not sure about the number of daily visits but here are a few examples of large Django sites:
- disqus.com (talk from djangocon)
- bitbucket.org (write up)
- lanyrd.com (source)
- support.mozilla.com (source code)
- addons.mozilla.org (source code) (talk from djangocon)
- theonion.com (write up)
- The guardian.co.uk comment system uses Django (source)
Here is a link to list of high traffic Django sites on Quora.
What’s the “largest” site that’s built on Django today? (I measure size mostly by user traffic)
In the US, it was Mahalo. I’m told they handle roughly 10 million uniques a month. Now, in 2019, Mahalo is powered by Ruby on Rails.
Abroad, the Globo network (a network of news, sports, and entertainment sites in Brazil); Alexa ranks them in to top 100 globally (around 80th currently).
Other notable Django users include PBS, National Geographic, Discovery, NASA (actually a number of different divisions within NASA), and the Library of Congress.
Can Django deal with 100k users daily, each visiting the site for a couple of hours?
Yes — but only if you’ve written your application right, and if you’ve got enough hardware. Django’s not a magic bullet.
Could a site like StackOverflow run on Django?
Yes (but see above).
Technology-wise, easily: see soclone for one attempt. Traffic-wise, compete pegs StackOverflow at under 1 million uniques per month. I can name at least dozen Django sites with more traffic than SO.
Scaling Web apps is not about web frameworks or languages, is about your architecture.
It’s about how you handle you browser cache, your database cache, how you use non-standard persistence providers (like CouchDB), how tuned is your database and a lot of other stuff…
Playing devil’s advocate a little bit:
You should check the DjangoCon 2008 Keynote, delivered by Cal Henderson, titled “Why I hate Django” where he pretty much goes over everything Django is missing that you might want to do in a high traffic website. At the end of the day you have to take this all with an open mind because it is perfectly possible to write Django apps that scale, but I thought it was a good presentation and relevant to your question.
The largest django site I know of is the Washington Post, which would certainly indicate that it can scale well.
Good design decisions probably have a bigger performance impact than anything else. Twitter is often cited as a site which embodies the performance issues with another dynamic interpreted language based web framework, Ruby on Rails – yet Twitter engineers have stated that the framework isn’t as much an issue as some of the database design choices they made early on.
Django works very nicely with memcached and provides some classes for managing the cache, which is where you would resolve the majority of your performance issues. What you deliver on the wire is almost more important than your backend in reality – using a tool like yslow is critical for a high performance web application. You can always throw more hardware at your backend, but you can’t change your users bandwidth.
I was at the EuroDjangoCon conference the other week, and this was the subject of a couple of talks – including from the founders of what was the largest Django-based site, Pownce (slides from one talk here). The main message is that it’s not Django you have to worry about, but things like proper caching, load balancing, database optimisation, etc.
Django actually has hooks for most of those things – caching, in particular, is made very easy.
I’m sure you’re looking for a more solid answer, but the most obvious objective validation I can think of is that Google pushes Django for use with its App Engine framework. If anybody knows about and deals with scalability on a regular basis, it’s Google. From what I’ve read, the most limiting factor seems to be the database back-end, which is why Google uses their own…
See further details as mentioned below:
It’s not uncommon to hear people say “Django doesn’t scale”. Depending on how you look at it, the statement is either completely true or patently false. Django, on its own, doesn’t scale.
The same can be said of Ruby on Rails, Flask, PHP, or any other language used by a database-driven dynamic website.
The good news, however, is that Django interacts beautifully with a suite of caching and
load balancing tools that will allow it to scale to as much traffic as you can throw at it.
Contrary to what you may have read online,
it can do so without replacing core components often labeled as “too slow” such as the database ORM or the template layer.
Disqus serves over 8 billion page views per month. Those are some huge numbers.
These teams have proven Django most certainly does scale.
Our experience here at Lincoln Loop backs it up.
We’ve built big Django sites capable of spending the day on the Reddit homepage without breaking a sweat.
Django’s scaling success stories are almost too numerous to list at this point.
It backs Disqus, Instagram, and Pinterest. Want some more proof? Instagram was able to sustain over 30 million users on Django with only 3 engineers (2 of which had no back-end development
Today we use many web apps and sites for our needs. Most of them are highly useful. I will show you some of them used by python or django.
The Washington Post’s website is a hugely popular online news source to accompany their daily paper. Its’ huge amount of views and traffic can be easily handled by the Django web framework.
Washington Post - 52.2 million unique visitors (March, 2015)
The National Aeronautics and Space Administration’s official website is the place to find news, pictures, and videos about their ongoing space exploration. This Django website can easily handle huge amounts of views and traffic.
2 million visitors monthly
The Guardian is a British news and media website owned by the Guardian Media Group. It contains nearly all of the content of the newspapers The Guardian and The Observer. This huge data is handled by Django.
The Guardian (commenting system) - 41,6 million unique visitors (October, 2014)
We all know YouTube as the place to upload cat videos and fails. As one of the most popular websites in existence, it provides us with endless hours of video entertainment. The Python programming language powers it and the features we love.
DropBox started the online document storing revolution that has become part of daily life. We now store almost everything in the cloud. Dropbox allows us to store, sync, and share almost anything using the power of Python.
Survey Monkey is the largest online survey company. They can handle over one million responses every day on their rewritten Python website.
Quora is the number one place online to ask a question and receive answers from a community of individuals. On their Python website relevant results are answered, edited, and organized by these community members.
A majority of the code for Bitly URL shortening services and analytics are all built with Python. Their service can handle hundreds of millions of events per day.
Reddit is known as the front page of the internet. It is the place online to find information or entertainment based on thousands of different categories. Posts and links are user generated and are promoted to the top through votes. Many of Reddit’s capabilities rely on Python for their functionality.
Hipmunk is an online consumer travel site that compares the top travel sites to find you the best deals. This Python website’s tools allow you to find the cheapest hotels and flights for your destination.
I think we might as well add Apple’s App of the year for 2011, Instagram, to the list which uses django intensively.
Yes it can. It could be Django with Python or Ruby on Rails. It will still scale.
There are few different techniques. First, caching is not scaling. You could have several application servers balanced with nginx as the front in addition to hardware balancer(s).
To scale on the database side you can go pretty far with read slave in MySQL / PostgreSQL if you go the RDBMS way.
Some good examples of heavy traffic websites in Django could be:
- Pownce when they were still there.
- Discus (generic shared comments manager)
- All the newspaper related websites: Washington Post and others.
You can feel safe.
Here’s a list of some relatively high-profile things built in Django:
The Guardian’s “Investigate your MP’s expenses” app
Politifact.com (here’s a Blog post talking about the (positive) experience. Site won a Pulitzer.
NY Times’ Represent app
Peter Harkins, one of the programmers over at WaPo, lists all the stuff they’ve built with Django on his blog
It’s a little old, but someone from the LA Times gave a basic overview of why they went with Django.
The Onion’s AV Club was recently moved from (I think Drupal) to Django.
I imagine a number of these these sites probably gets well over 100k+ hits per day. Django can certainly do 100k hits/day and more. But YMMV in getting your particular site there depending on what you’re building.
There are caching options at the Django level (for example caching querysets and views in memcached can work wonders) and beyond (upstream caches like Squid). Database Server specifications will also be a factor (and usually the place to splurge), as is how well you’ve tuned it. Don’t assume, for example, that Django’s going set up indexes properly. Don’t assume that the default PostgreSQL or MySQL configuration is the right one.
Furthermore, you always have the option of having multiple application servers running Django if that is the slow point, with a software or hardware load balancer in front.
Finally, are you serving static content on the same server as Django? Are you using Apache or something like nginx or lighttpd? Can you afford to use a CDN for static content? These are things to think about, but it’s all very speculative. 100k hits/day isn’t the only variable: how much do you want to spend? How much expertise do you have managing all these components? How much time do you have to pull it all together?
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