Real example of multithreaded QHttpServer?

[apaczenko1993]

Hello, i tried to create multi-thread API for my apps, so my goal is to create multithreaded http server, with ability to process many route in the same time. I saw in doc this example:

server.route("/feature/", [] (int id) {
    return QtConcurrent::run([] () {
        return QHttpServerResponse("the future is coming");
    });
});

But in my opinion this doesn't work, like I want. I have created route with 5 sec msleep delay. But during the test I saw that second request is processing after when first will end. One positive i that GUI will no frezze.

Does anybody know, how to create real multithread http server? My Qt is 6.5.3. Maybe using QThread or QThreadPool?

[ChrisW67]

This code:

#include <QCoreApplication>
#include <QTcpServer>
#include <QHttpServer>
#include <QtConcurrent>
#include <QDebug>

QHttpServerResponse handleRequest(int id) {
        qDebug() << "Start" << id << QThread::currentThread();
        QThread::sleep(5);
        qDebug() << "Finish" << id;
        return QHttpServerResponse("response text\n");
}

int main(int argc, char **argv) {
        QCoreApplication app(argc, argv);

        QHttpServer server;

        server.route("/", [] (int id) {
                return QtConcurrent::run(&handleRequest, id);
        });

        auto tcpserver = new QTcpServer(qApp);
        if (!tcpserver->listen(QHostAddress::Any, 30000) || !server.bind(tcpserver)) {
            return -1;
        }
        qDebug() << "Listening on port" << tcpserver->serverPort();

        return app.exec();
}

Produces results like this:

 ./test 
Listening on port 30000
Start 0 QThreadPoolThread(0x5d512f61d580, name = "Thread (pooled)")
Start 2 QThreadPoolThread(0x5d512f8b6400, name = "Thread (pooled)")
Start 1 QThreadPoolThread(0x5d512f62ecb0, name = "Thread (pooled)")
Start 4 QThreadPoolThread(0x5d512f630430, name = "Thread (pooled)")
Start 3 QThreadPoolThread(0x5d512f8b6ce0, name = "Thread (pooled)")
Finish 0
Finish 4
Finish 1
Finish 2
Finish 3
^C

when tested with:

curl -o -   http://localhost:30000/0 &
curl -o -   http://localhost:30000/1 &
curl -o -   http://localhost:30000/2 &
curl -o -   http://localhost:30000/3 &
curl -o -   http://localhost:30000/4 &

Request processing is interleaved, multi-threaded. The size of the thread pool is limited so more requests will start waiting. Using curl --parallel changes the behaviour with respect to the first request curl sends.