The first step was a 15-minute call with the hiring manager, and I was asked a handful of very light technical questions.

I was then immediately sent a 4-hour timed exam on Codility. This was the longest exam I have been asked for as a screener, especially without having first talked to any engineers on the team.

After submitting the exam (which was failing 1 of the roughly 12 "not-secret" unit tests), I was quickly informed I didn't pass the next day. The hiring team was quick to respond and helpful.

My only complaint was that I wished the screener was more in line with 1 hour, or that I was able to talk to someone on the team before committing to a 4-hour exam.

The exam consisted of three tasks.

The first included a bash exercise for finding lines in files.

The second tested knowledge of message passing between processes with a large number of constraints.

The third tested a common ETL procedure for training models.

The bash and message passing algorithms were a little tricky, as there was no way to easily test the code locally.

Overall, the questions seemed relevant and of appropriate difficulty.