Technology

The Easy Way to Increase Your API Performance

Shahar Glazner
July 25, 2021

Our platform, anecdotes.ai, is an Angular Single Page Application (SPA), which has several main components. When you log in into the platform, Angular triggers 3 API requests to the anecdotes backend, each representing a component. While waiting for a response, the UI shows a loading page so it’s clear why our goal, as backend developers, is to reduce this time as much as we can.

As you can see, we have:

  • Framework endpoint: ~6 seconds
  • Control endpoint: ~4 seconds
  • Service endpoint: ~3 seconds

Summing  it up, I’ll use the words of Chrenobyl’s Dyatlov:

One evening, Tal Borenstein and I started to bounce around some ideas on how to reduce the loading time.

Here I should describe the stack that our backend is built on:

  • Programming language — Python
  • Database — Snowflake
  • Web stack — Gunicorn + Flask
  • ORM — SQLAlchemy

Each of these parts could potentially cause performance problems.

To take the discussion to a more professional level, we decided to use a profiler so we would have some idea of what was going on. I’ll focus on one specific endpoint (/control) but the general idea is the same for the other two.

Let’s review the first profiler iteration:

At first sight, it didn’t tell us a lot, but there was one thing that caught our attention:

The function “get_specific_global_control” was invoked 3586 times, and it triggered another function (“get”) 1084112 times (!), taking 40% of the processing time!

We jumped to the code and reviewed the implementation:


We could immediately see that although we used a cache so that we wouldn’t query the database for each control, each invocation of “get_specific_global_control” took o(N) (where N is the number of controls in our system) to find a specific control!

This could have been immediately reduced just by keeping the cache as a dictionary and not as a list.

It would make the get_specific_global_control run in O(1) instead of O(N).

Now that we made this change, let’s review our second iteration of profiling and see if it helped:

You can see that now, control_facade:control_related_controls takes only 4%(!) of the processing time. It had previously taken 58% of the processing time.

So what’s next?

The next thing that caught our eye was the “get_services_that_automate” function, which now, after the second iteration, took 40% of the time.

This function should have returned a list of services that automated a specific control. This is a new property that was added recently, and we didn’t expect it to cause such significant performance degradation. The root cause for that “get_services_that_automates” function taking so long is that it queried the database, instead of using already-queried data. We bypassed this by adding this property as a column to the already-queried object (control), so we now get this property “for free”.

So here’s our third iteration of profiling. After holding the controls cache as a dictionary instead of a list AND refactoring “get_services_that_automates” to use an already-queried object instead of querying the database, we managed to reduce around 50%~ of the time for our APIs.

Let’s see now how the platform behaves and compare the results:

Summary

Finally, we can review the “performance blitz” results in a simple table, showing a performance enhancement of 67%.

So there you have it; how we improved performance by A LOT in one day. It involved a bit of playing around and experimentation but that’s what we love doing here at anecdotes—seeing how already-decent processes can be made even better and optimizing what’s already good.

Shahar Glazner
Passionate about technology, sports, economy, chess and system architecture in a cloud-native world. A long-distance runner and Lead Developer at anecdotes.

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