Improve ElasticManager

[oschulz]

Adds several things to ElasticManager:

• An callback option - this can be used to automatically run init code on new workers, add them to and remove them from worker pools, add custom logging when workers connect, etc.

• More debug logging - often necessary to find out what's wrong if workers won't connect.

• Add a mechanism to forward environment variables to workers. Havent' found a way to set them before the Julia worker process starts up, but at least sets them before it does anything.

I'm field-testing this via a local copy of ElasticManager in ParallelProcessingTools.jl (will release a new version soon) so I can make breaking changes still if necessary, but I'll keep this PR in sync to upstream once it seems fully stable (looking pretty good so far, so hopefully soon).

[oschulz]

CC @JBlaschke , thanks for pointing out the potential of ElasticManager to me.

[oschulz]

Will take a bit longer before I upstream the ElasticManager changes from ParallelProcessingTools, I want to see if there's a clean way to handle network device selection and if that requires interface changes.

[oschulz]

@DilumAluthge , sorry, I neglected this a bit, I should really get on with getting this release-ready.

[DilumAluthge]

@oschulz We currently do not have a maintainer for the ElasticManager functionality in this package.

Do you actively use the ElasticManager functionality? If so, would you be interested in becoming the maintainer for the ElasticManager functionality?

[DilumAluthge]

Also @oschulz it looks like there are some merge conflicts here.

Could you rebase this PR and fix the merge conflicts?

[oschulz]

Do you actively use the ElasticManager functionality?

Yes, we do, quite actively, but currently the experimental version in ParallelProcessingTools. The plan is still to re-upstream it though.

I'll rebase and test an get on with this - gimme a bit.

If so, would you be interested in becoming the maintainer for the ElasticManager functionality?

Sure, I can take that over.

[DilumAluthge]

For the other cluster managers (e.g. Slurm and LSF), I've moved the managers out to separate packages (SlurmClusterManager.jl and LSFClusterManager.jl), with the idea being that each manager has different maintainers, tests, CI, etc.

What do you think about moving the elastic manager out to a new standalone package, e.g. ElasticClusterManager.jl?

[oschulz]

What do you think about moving the elastic manager out to a new standalone package, e.g. ElasticClusterManager.jl?

I'd be all for it! We have to release a ClusterManagers v2.0 then though, right?

[DilumAluthge]

I'd be all for it! We have to release a ClusterManagers v2.0 then though, right?

Yep, which I'll need to do anyway once I remove Slurm from this package.

[oschulz]

Yep, which I'll need to do anyway once I remove Slurm from this package.

Ok, that's perfect then. Because I can then upstream my changes to ElasticClusterManager directly - I was hestiant to do that because I suspected I might need to do more breaking changes. But if ElasticClusterManager has it's own version number, it's easy.

[DilumAluthge]

I created the new repo:

@oschulz I've invited you to the repo: https://github.com/JuliaParallel/ElasticClusterManager.jl

You can accept the invitation here: https://github.com/JuliaParallel/ElasticClusterManager.jl/invitations

[oschulz]

@oschulz I've invited you to the repo. You can accept the invitation here:

Thanks!