Terminate worker using threadId

[amansanghvi]

Hey, I can't find any current examples of it working, and I don't think it's implemented, but I think it would be really useful to be able to do a lookup of workers using a threadId.

Currently if you want to kill a worker you have to hold the worker instance and call terminate(), or have some sort of shared memory. I think because we have a threadId, it would be good to have a way to kill a worker using that Id. Thoughts?

This could also be expanded to having a lookup for a worker using the threadId so we don't have to pass around an object and can pass a threadId instead.

[jasnell]

I'm not sure what version it has been back ported to, but it would be fairly simple to implement this using the new process.on('worker') event. It does require holding the reference to the worker instance but it would be fairly easy to implement in a dedicated module.