send a target to a second worker in clustermq parallelism

[kendonB]

Prework

• Read and abide by drake's code of conduct.
• Search for duplicates among the existing issues, both open and closed.

Proposal

I found a case where a dynamic target got really close to finishing but did not while I still had workers up and waiting for work. What I suspect happened was that targets were allocated to workers that then disappeared due to the HPC time limit. What I would have liked to have happened was that drake would recognise that the worker has disappeared then send the target to another worker that is still around.

I believe this would require clustermq to be able to say which workers have disappeared via SLURM in my case.

[wlandau]

Unfortunately, drake has no way of knowing which clustermq workers stopped unexpectedly or which target was running at the time. Maybe follow up on mschubert/clustermq#101.