Defer not working in multithreaded app

[FabianHummel]

I cannot close the app through another thread, even though I am using uWS::Loop::defer already. Am I doing something wrong?

uWebSockets Version 20.62.0

void on_open(WebSocketType* ws) {
    loop_ = uWS::Loop::get();
    socket = ws;
    update_status(CONNECTED);
}

void on_close(int code, std::string_view message) {
    socket = nullptr;
    update_status(PENDING);
}

void init() {
    std::cout << "Initializing µWebSockets..." << std::endl;

    if (uWSThread_.joinable()) uWSThread_.join();

    uWSThread_ = std::thread([] {
        uWSApp = std::make_unique<uWS::App>();

        uWSApp->get("/status", [](auto *res, auto *req) {
            res ->writeStatus("200 OK")
                ->writeHeader("Content-Type", "application/json")
                ->writeHeader("Access-Control-Allow-Origin", "*")
                ->end(R"({"status":"ok"})");
        })

        .ws<UserData>("/*", {
            .open = [](WebSocketType *ws) {
                on_open(ws);
            },
            .close = [](WebSocketType*, const int code, const std::string_view message) {
                on_close(code, message);
            },
            .message = [](WebSocketType*, std::string_view message, uWS::OpCode opCode) {
                on_message(message, opCode);
            }
        })

        .listen(9001, [](auto *listenSocket) {
            if (listenSocket) {
                listenSocket_ = listenSocket;
                std::cout <<
                    "Thread " << std::this_thread::get_id() <<
                    " listening on port " << us_socket_local_port(true, (struct us_socket_t *) listenSocket) << std::endl;
            } else {
                std::cout << "Failed to bind to port" << std::endl;
            }
        })

        .run();

        std::cout << "µWebSockets closed" << std::endl;
    });
}

void close() {
    loop_->defer([](){
        uWSApp->close();
    });
}

[uNetworkingAB]

You need to get the Loop from the thread you want to "defer" to. Right now you're getting the loop from the current thread and deferring from that thread, to that thread.

[FabianHummel]

i got the loop from the thread where uWebSockets is running and called it from the main thread. Keep in mind that I call close() in response of a UI event and not within uWS. When I add debug lines, it clearly states that the loop is acquired in another thread than the one deferring to it:

void init() {
    std::cout << "Initializing µWebSockets..." << std::endl;

    if (uWSThread_.joinable()) uWSThread_.join();

    uWSThread_ = std::thread([] {
        std::cout << std::this_thread::get_id() << std::endl; // 0x16da7b000
        loop_ = uWS::Loop::get();
        
        uWSApp = std::make_unique<uWS::App>();
        
        // rest of code...
    }
}

void close() {
    std::cout << std::this_thread::get_id() << std::endl; // 0x1fb2ccf40
    loop_->defer([](){
        uWSApp->close();
    });
}

[FabianHummel]

Fixed it because I had been experiencing issues with c++ translation units (splitting code into header files) and using the wrong keywords. My issue has nothing to do with uWebSockets. Sorry for confusion, closing now.