cancel CI workflow that becomes obsolete after a new commit is pushed in an open PR

[kitsiosk]

Change Summary

Currently, if a PR is open and a push happens, the Automated checks workflow will start running. If, shortly after a subsequent push on the same PR happens, the workflow will start running again without cancelling the previous (now obsolete) run. With these changes, the first run would be cancelled, thus saving compute resources (see below for quantity) without sacrificing functionality, since the second run will contain the changes from the first push as well.

Context

Hi,

We are a team of researchers from University of Zurich and we are currently working on energy optimizations in GitHub Actions workflows.

Here is an example of the behaviour described above: the commit 9ee1663 triggered this workflow run, and shortly after the commit 3fe0a02, that happened on top of the first commit, triggered this workflow. Both workflows ran till the end, spending approximately 57 CPU seconds each. With the proposed changes, the first run would be cancelled, hence saving ~6.0 CPU seconds and clearing the queue for other workflows. Note that this is an example of a single concurrent run, and the accumulated gain for all PRs would be higher.

Kindly let us know (here or in the email below) if you would like more details, if you want to reject the proposed changes for other reasons, or if you have any question whatsoever.

Best regards,
Konstantinos Kitsios
konstantinos.kitsios@uzh.ch

PS: Some hyperlinks may not work if the corresponding workflows have been deleted.