After thinking about it some more, I think the way to do what I've proposed is to implement some locking between the worker and the issuer. Doing this requires a manager in the middle somewhere. The manager would need to hold the jobs in a queue and wait for the workers to request jobs/indicate readiness to receive jobs.

I'm also not sure that my approach is the best. It might be better to provide for the option of spreading my workers across multiple machines. Naturally, that will mean implementing TCP connections instead of pipes. It will likely also mean a more complex startup process, and much more complex management.