fixed the limited issue

worker/worker.go

@@ -259,11 +259,11 @@ func (worker *Worker) exec(job *Job) (err error) {
     }
     var result []byte
     if worker.limit != nil {
+        select {
+        case <-worker.limit:
             defer func() {
                 worker.limit <- true
             }()
-        select {
-        case <-worker.limit:
         case <-time.After(time.Second * time.Duration(f.timeout)):
             err = common.Errorf("The function was executed timeout: %s", funcname)
         }