[chi_features]

> Given that the Intercom monolith CI runs with 1350 parallel workers by default

Wow! I'd love to hear more about how that's achieved

[byroot]

Nothing ground breaking we simply deploy Buildkite agents on EC2 nodes.

As mentioned in the post, the only thing really limiting CI parallelism is the ratio of "setup time" vs "test time". If your setup time is too long, you hit diminishing returns fast.

[chi_features]

Thank you for sharing – with 1350 workers I can appreciate the reduction of setup time!

[faangguyindia]

It's because it probably uses Ruby on Rails which has to launch 1000s of os process to handle any traffic.

[kimos]

This makes no sense and has nothing to do with serving traffic.

More EC2 workers means more parallelism means tests map to more workers and the CI build finishes faster. It’s just CI perceived complete time.