fix bug

server/workerManager.go

@@ -78,6 +78,7 @@ type WorkerManager struct {
 func NewWorkerManager(rdb *redis.Client, node *Node) *WorkerManager {
 	return &WorkerManager{
 		heartBeat: make(map[int64]int64),
+		workerReg: make(map[int64]*registry.Registry),
 		workers:   make(map[int64]*Worker),
 		workid:    make(map[string]*Worker),
 		quit:      make(chan struct{}),