See post referencing Turnstyle.
I added the action and it blocked until the already running action completed.
Thanks @softprops . I’d consider this featured request solved.
Thanks Github for making Actions flexible enough to allow the community to help make Actions feature rich.
If actions happen fast, there are a lot of room for two actions getting green light and starting at the same time.
Quite easy to reproduce with repository dispatch event and curl. Just do two at the same time, and you’ll get two running actions at the same time. Race condition, because there is no real lock acquired by the action, only checking if no actions run at current point in time.
