// checkOld can be set to an expected value.
// If the worker count changed
func (p *ReplicationPool) ResizeWorkers(n, checkOld int) {
	p.mu.Lock()
	defer p.mu.Unlock()

	if (checkOld > 0 && len(p.workers) != checkOld) || n == len(p.workers) || n < 1 {
		// Either already satisfied or worker count changed while we waited for the lock.
		return
	}
	for len(p.workers) < n {