nomad: disable one worker when leader

nomad/leader.go

@@ -98,6 +98,12 @@ WAIT:
 // previously inflight transactions have been commited and that our
 // state is up-to-date.
 func (s *Server) establishLeadership(stopCh chan struct{}) error {
+	// If we have multiple workers, disable one to free processing
+	// for the plan queue and evaluation broker
+	if len(s.workers) > 1 {
+		s.workers[0].SetPause(true)
+	}
+
 	// Enable the plan queue, since we are now the leader
 	s.planQueue.SetEnabled(true)
 
@@ -243,6 +249,11 @@ func (s *Server) revokeLeadership() error {
 		s.logger.Printf("[ERR] nomad: clearing heartbeat timers failed: %v", err)
 		return err
 	}
+
+	// Unpause our worker if we paused previously
+	if len(s.workers) > 1 {
+		s.workers[0].SetPause(false)
+	}
 	return nil
 }