Web API performance: profiling Django REST framework
We’ve seen several cases of developers making these assumptions before they start building their API, and either discounting Django as not being fast enough for their needs, or deciding to not use a Web API framework such as Django REST framework because they ‘need something lightweight’.
I’m going to be making the case that Web API developers who need to build high performance APIs should be focusing on a few core fundamentals of the architecture, rather than concentrating on the raw performance of the Web framework or API framework they’re using.
.. the biggest performance gains for Web APIs can be made not by code tweaking, but by proper caching of database lookups, well designed HTTP caching, and running behind a shared server-side cache if possible.
.. 1. Get your ORM lookups right.
Given that database lookups are the slowest part of the view it’s tremendously important that you get your ORM queries right. Use
.select_related()and.prefetch_related()on the.querysetattribute of generic views where necessary. If your model instances are large, you might also consider usingdefer()oronly()to partially populate the model instances.2. Your database lookups will be the bottleneck.
.. 3. Work on performance improvements selectively.
Remember that premature optimization is the root of all evil. Don’t start trying to improve the performance of your API until you’re in a position to start profiling the usage characteristics that your API clients exhibit. Then work on optimizing your views selectively, targeting the most critical endpoints first.