update default conn pre host

request.go

@@ -92,6 +92,7 @@ func newRequest(method, uri, certPath, keyPath string, header map[string]string,
 			c.SetDeadline(time.Now().Add(time.Second * reqTimeOut))
 			return c, nil
 		},
+		MaxIdleConnsPerHost:   50,
 		ResponseHeaderTimeout: time.Second * reqTimeOut,
 	}