How to set multiple worker threads for a undertow server listener?

Question

I am trying to create multiple worker threads for the undertow server so that multiple threads are available to process the request from the client concurrently. I tried setting them at the server level using UndertowOptions and Options. Tried creating custom XnioWorker and assigned to Undertow Server.

Nothing seems to work here, with all attempts to configure worker threads.

Xnio xnio = Xnio.getInstance();
        XnioWorker worker = null;
        try {
            worker = xnio.createWorker(
                    OptionMap.builder().set(Options.WORKER_IO_THREADS, 50).set(Options.WORKER_TASK_CORE_THREADS, 50)
                            .set(Options.WORKER_TASK_MAX_THREADS, 50).set(Options.TCP_NODELAY, true).getMap());
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
//      OptionMap socketOptions = OptionMap.builder().set(Options.WORKER_IO_THREADS, 10).set(Options.TCP_NODELAY, true)
//              .set(Options.REUSE_ADDRESSES, true).getMap();

        Undertow server = Undertow.builder().setServerOption(UndertowOptions.ENABLE_HTTP2, true)
                .setServerOption(UndertowOptions.HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS,
                        UndertowHttp2ServerEpLevel.maxReqPerConn)
                .setServerOption(UndertowOptions.MAX_CONCURRENT_REQUESTS_PER_CONNECTION,
                        UndertowHttp2ServerEpLevel.maxReqPerConn)
                .addHttpListener(port, host)
                .setWorkerOption(Options.WORKER_IO_THREADS, 10)
                .setWorkerOption(Options.WORKER_TASK_CORE_THREADS, 10)
                .setWorkerThreads(UndertowHttp2ServerEpLevel.iotheads)
                .setIoThreads(UndertowHttp2ServerEpLevel.iotheads)
                .setWorker(worker)
                .setHandler(exchange -> {

                    Thread.sleep(responseDelayInMs);

                    DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
                    Date date = new Date();

                    System.out.print(dateFormat.format(date) + ", **Thread name: " + Thread.currentThread().getName());**
                    System.out.println(
                            ": " + port + ", Client address is: " + exchange.getConnection().getPeerAddress().toString()
                                    + " TotalMsgReceived: " + ++msgCounter);

                    exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "application/json");
                    exchange.setStatusCode(returnCode);
//                  exchange.getResponseSender().send("Undertow Hi");
               
                }).build();
        server.start();

With the above code i see handler code is always executed by same thread. And with one thread with n/w latency assumed 100ms i am able process only 9 request per second. Thats why i want more number of threads to process request concurrently so that high rate can be achieved.

Console output:

*2021/07/29 09:22:46, Thread name: XNIO-1 I/O-12: 8081, Client address is: /127.0.0.1:16002 TotalMsgReceived: 534

2021/07/29 09:22:47, Thread name: XNIO-1 I/O-12: 8081, Client address is: /127.0.0.1:16002 TotalMsgReceived: 535*

Now from JMX i see thread pool size is updated to 50 but still no improvement in perfromance and no multi worker threads seen in console:

Any view on this will help. Thanks!

Answer 1

Following code does the job.

Undertow server = Undertow.builder().setServerOption(UndertowOptions.ENABLE_HTTP2, true)
                .setServerOption(UndertowOptions.HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS,
                        UndertowHttp2ServerEpLevelMT.maxReqPerConn)
                .setServerOption(UndertowOptions.MAX_CONCURRENT_REQUESTS_PER_CONNECTION,
                        UndertowHttp2ServerEpLevelMT.maxReqPerConn)
                .addHttpListener(port, host)
                .setWorkerOption(Options.WORKER_IO_THREADS, UndertowHttp2ServerEpLevelMT.iotheads)
                .setWorkerOption(Options.WORKER_TASK_CORE_THREADS, UndertowHttp2ServerEpLevelMT.iotheads)
                .setWorkerOption(Options.WORKER_TASK_MAX_THREADS, UndertowHttp2ServerEpLevelMT.iotheads)
                .setWorkerThreads(UndertowHttp2ServerEpLevelMT.iotheads)
                .setIoThreads(UndertowHttp2ServerEpLevelMT.iotheads)
                .setHandler(new HttpHandler() {
                    @Override
                    public void handleRequest(final HttpServerExchange exchange) throws Exception {
                        if (exchange.isInIoThread()) {
                            exchange.dispatch(this);
                            return;
                        }
                        System.out.println("Port: " + port + ", Client address is: "
                                + exchange.getConnection().getPeerAddress().toString());
                        exchange.setStatusCode(returnCode);
                    }
                }).build();
        server.start();

Answer 2

From the documentation

Dispatching to a worker thread

public void handleRequest(final HttpServerExchange exchange) throws Exception{
    if (exchange.isInIoThread()) {
      exchange.dispatch(this);
      return;
    }
    //handler code
}

You seem to be missing this part, because everything in your case is running on IO thread.

There are multiple overloads of dispatch method that you can choose from depending on your use case.