2019-05-09 20:27
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var userConn *grpc.ClientConn
var userServiceName string

func init() {
    userServiceName := os.Getenv("USER_SERVICE_URL")
    if userServiceName == "" {
        userServiceName = "localhost"
    logging.LogDebug("userClient:  Connecting to: "+userServiceName, "")
    tempConn, err := grpc.Dial(userServiceName, grpc.WithInsecure())
    if err != nil {
        logging.LogEmergency("account_user_client.Init()  Could not get the connection.  "+err.Error(), "")
    userConn = tempConn


c := user.NewUserClient(userConn)
// Contact the server and print out its response.
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
r, err := c.GetUserFromTokenID(ctx, &user.GetUserFromTokenRequest{TransactionID: transactionID, OathToken: *oathToken})
//Handle Error and Response



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2条回答 默认 最新

  • douqiang4501 2019-05-09 22:48

    Yes, it's fine to have single GRPC client connection per service. Moreover, I don't see any other options here. GRPC does all the heavy lifting under the hood: for example, you don't need to write your own client connection pool (as you would do for a typical RDBMS), because it won't provide better results than a single GRPC connection.

    However I would suggest you to avoid using global variables and init functions, especially for networking setup. Also you don't need to create GRPC client (c := user.NewUserClient(userConn)) every time you post a request to the GRPC service: this is just an extra work for garbage collector, you can create the only instance of client at the time of application startup.


    Assuming that you're writing server application (because it can be seen from the method you call on the remote GRPC service), you can simply define a type that will contain all the objects that have the same lifetime as the whole application itself. According to the tradition, these types are usually called "server context", though it's a little bit confusing because Go has very important concept of context in its standard library.

       // this type contains state of the server
       type serverContext struct {
           // client to GRPC service
           userClient user.UserClient
           // default timeout
           timeout time.Duration
           // some other useful objects, like config 
           // or logger (to replace global logging)
           // (...)       
       // constructor for server context
       func newServerContext(endpoint string) (*serverContext, error) {
           userConn, err := grpc.Dial(endpoint, grpc.WithInsecure())
           if err != nil {
               return nil, err
           ctx := &serverContext{
              userClient: user.NewUserClient(userConn),
              timeout: time.Second,
           return ctx, nil
       type server struct {
           context *serverContext
       func (s *server) Handler(ctx context.Context, request *Request) (*Response, error) {
           clientCtx, cancel := context.WithTimeout(ctx, time.Second)
           defer cancel()
           response, err := c.GetUserFromTokenID(
                  TransactionID: transactionID,
                  OathToken: *oathToken,
           if err != nil {
                return nil, err
           // ...
       func main() {
           serverCtx, err := newServerContext(os.Getenv("USER_SERVICE_URL"))
           if err != nil {
           s := &server{serverCtx}
           // listen and serve etc...

    Details may change depending on what you're actually working on, but I just wanted to show that it's much more better to encapsulate state of your application in an instance of distinct type instead of infecting global namespace.

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  • helloworld_coder 2020-07-27 17:43


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