Why is Mosquitto broker and Paho client running CPU 100% on connection?

Question

I would like to use the mosquitto MQTT broker using Websockets. I am running mosquitto version 1.6.2 on a Debian 8 server. "normal" MQTT works fine, but I am having a problem trying to connect using websocket.

I am using paho javascript client both https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.0.1/mqttws311.js and https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.0.1/mqttws31.js

Same problem using

https://unpkg.com/mqtt@3.0.0/dist/mqtt.min.js

Following Steves internet guide tutorials.

The problem is that the client connects to the broker, but is seems that is constantly running the "onConnect" function. In this function it is possible to subscribe to a topic and send a message, which works, but a lot, like 1000 times a second. This is the problem. But the computer running the client as the server starts running 100% CPU.

In the mosquitto broker logs I see the clients only connects once. I can still publish from other client (mosquitto_pub) on the same topic and you can see the message in between the thousands of messages being send from the Paho client.

Does someone know what I can do?

This is a part of the javascript client code:

  function onFailure(message) {
        console.log("Connection Attempt to Host "+host+" Failed");
        console.log(message);
        setTimeout(MQTTconnect, reconnectTimeout);
    }
    function onMessageArrived(msg){
        out_msg="Message received "+msg.payloadString+"<br>";
        out_msg=out_msg+"Message received Topic "+msg.destinationName;
        console.log(out_msg);

    }

    function onConnect() {
  // Once a connection has been made, make a subscription and send a message.

    console.log("Connected ");
    mqtt.subscribe("sensor1");
    message = new Paho.MQTT.Message("Hello World");
    message.destinationName = "sensor1";
    mqtt.send(message);
  }

  function onConnectionLost(responseObject) {
      if (responseObject.errorCode !== 0) {
        console.log("onConnectionLost:"+responseObject.errorMessage);
      }
    }

  function MQTTconnect() {
    console.log("connecting to "+ host +" "+ port);
    mqtt = new Paho.MQTT.Client(host,port,"clientjs-hoi");
    //document.write("connecting to "+ host);
    var options = {
        timeout: 30,
        onSuccess: onConnect,
        onFailure: onFailure,
         };
    mqtt.onMessageArrived = onMessageArrived;
    mqtt.onConnectionLost = onConnectionLost;

    mqtt.connect(options); //connect
    }

A sample of what happens in the console:

At the server:

In the log at see only once:

1560802249: New client connected from x.x.x.x as clientId-Tdbml6TORG (p1, c1, k60).