don't hang on panic in Run()

[umanwizard]

Right now we just hang forever waiting on this wg if we panic anywhere under Run, so the panic will never be reported, the process will never be restarted, etc.

To fix this, re-raise the panic and don't call wg.Wait() if we're panicking.

[gnurizen]

I don't get it, why wouldn't the panic blow right passed the Wait()? Is there another recover involved?

[umanwizard]

@gnurizen Defers do still run when unwinding the stack for a panic.

[gnurizen]

Ah that makes sense, I would have looked at fixing it by removing the defer, calling Wait in a defer seems questionable.

[gnurizen]

Actually what we should probably be doing is passing a new derived context to all the CPU sub-goroutines and we should cancel that before we call wait, ie:

    ctx,cancel = context.WithCancel(ctx)
    var wg sync.WaitGroup
    defer cancel()
    defer wg.Wait()
    ...

Then we should only wait until the other go-routines get the cancel signal and return.