increase max idle conn per hosts

weed/util/grpc_client_server.go

@@ -20,7 +20,7 @@ var (
 )
 
 func init() {
-	http.DefaultTransport.(*http.Transport).MaxIdleConnsPerHost = 100
+	http.DefaultTransport.(*http.Transport).MaxIdleConnsPerHost = 1024
 }
 
 func NewGrpcServer(opts ...grpc.ServerOption) *grpc.Server {