Open Source Summit Japan

Slowness of CI is a critical issue in software development, because it discourages engineers from writing tests, and hence deteriorates the quality of the product.

In this presentation, Akihiro Suda will talk about how to accelerate CI by executing test functions in parallel, across a Docker Swarm-mode cluster.
One of the major challenges was the nonuniformity of the makespan. e.g. some chunk of test functions can take 30 minutes, some chunk can take just 10 seconds...
So, he mitigates such a nonuniformity by randomizing the composition of chunks of test functions.

As a result, for example, the integration test of Docker itself that had taken more than 80 minutes can be finished in 4 minutes, with 10 Docker Swarm-mode nodes.
This hack can be easily applied to CI of other software as well.