Golang gRPC 无法保持事件状态 : the client connection is closing

Question

嗨，我正在尝试将 gRPC 客户端连接到服务器，但即使连接成功，我在从 graphql 解析器查询它时也会收到以下错误。但是，如果我直接从解析器拨号，一切正常，因此它与客户端不保持连接打开有关。

rpc 错误:代码 = Canceled desc = grpc:客户端连接正在关闭

客户端

var kacp = keepalive.ClientParameters{
    Time:                10 * time.Second, // send pings every 10 seconds if there is no activity
    Timeout:             time.Second,      // wait 1 second for ping back
    PermitWithoutStream: true,             // send pings even without active streams
}

func gqlHandler() http.HandlerFunc {

    conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithInsecure(), 
    grpc.WithKeepaliveParams(kacp),
    grpc.WithBlock())

    if err != nil {
        panic(err)
    }
    defer conn.Close()

    db := proto.NewPlatformDBClient(conn)

    gh := handler.GraphQL(platform.NewExecutableSchema(platform.Config{Resolvers: &platform.Resolver{
        DB: db,
    }}))

    gh = cors.Disable(gh)

    return gh
}

Answer 1

它是因为defer conn.Close()命令将在使用连接之前执行。
From the go blog

A defer statement pushes a function call onto a list. The list ofsaved calls is executed after the surrounding function returns.

所以你会删除行 defer conn.Close()并在不再使用后关闭连接。