public class Demo extends AbstractVerticle {

  @Override
  public void start(Promise<Void> start) {
    // wrap this block as a Virtual Thread so we can await (block) at any time
    // without interfere with the event loop
    asyncRun(() -> {
      Redis redis = Redis.createClient(
        vertx,
        new RedisOptions().setMaxPoolSize(32).setMaxPoolWaiting(128));

      System.out.println("Will count calls to: counter");
      // look blocking but not the event loop!
      await(redis.send(cmd(SET).arg("counter").arg(0)));

      vertx
        .createHttpServer()
        // handler's are non blocking by nature, so like in JavaScript we just mark then as
        // "async()" this will start a new virtual thread and ensure we can block at any time
        .requestHandler(async(req -> {
          try {
            // we block by waiting on the redis response
            var set = await(redis.send(cmd(INCR).arg(key)));
            // and return the result, no more chains of flatMap(), compose(), onXYZ()...
            req.response().end(set.toString());
          } catch (RuntimeException e) {
            // exceptions are now also handled as simple try-catch
            req.response()
              .setStatusCode(500)
              .end(e.getMessage());
         }
      }))
      .listen(8000, "0.0.0.0")
      .<Void>mapEmpty()
      .onComplete(start);
    });
  }
}

~/Projects/tmp $ wrk -t2 -c100 -d10s http://127.0.0.1:8000
Running 10s test @ http://127.0.0.1:8000
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     4.62ms   12.54ms 212.71ms   97.60%
    Req/Sec    17.23k     5.85k   23.93k    78.79%
  339750 requests in 10.01s, 14.15MB read
Requests/sec:  33932.29
Transfer/sec:      1.41MB
~/Projects/tmp $ wrk -t2 -c100 -d10s http://127.0.0.1:8000
Running 10s test @ http://127.0.0.1:8000
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     2.48ms    0.98ms  24.25ms   94.57%
    Req/Sec    20.64k     1.90k   23.65k    94.50%
  410919 requests in 10.00s, 17.24MB read
Requests/sec:  41071.70
Transfer/sec:      1.72MB
~/Projects/tmp $