Add non-recursive GetPids?

[jimmidyson]

We are migrating from docker/libcontainer to here & one issue for us is the implementation of GetPids is now recursive. In Kubernetes we use this project's cgroups functionality to get pids from a particular cgroup & move (Apply) them to another one, but we don't want to do this recursively.

How would you feel in adding a non-recursive GetPids? Pretty trivial implementation wise, but not sure how you'd feel about that?

[LK4D4]

It sounds ok to me. Recursive behavior is not very common for such func.

[jimmidyson]

It was your PR (#330) that made it recursive 😜

So how do you want to proceed? I'd prefer GetPids to be non-recursive & users walk the cgroup hierarchy themselves if they want to get pids from all sub-cgroups, but changing that functionality back to how it was would impact on existing users of the new GetPids (including Docker afaik). I can put in a PR for this if you let me know how you want to proceed.

[vishh]

Or we can provide both alternatives - GetPids and GetAllPids maybe?

[LK4D4]

@vishh +1

[vishh]

Ok. I'll send a patch in a bit. Hopefully @jimmidyson hasn't started working on a patch already.

[jimmidyson]

I'm nearly done tbh.

[vishh]

@jimmidyson: 👍