Publishing 2048 bytes messages at a high rate, they are lost at all QOS about aedes HOT 10 CLOSED

// mqtt-test.js
/*jslint node: true, esversion: 6 */
'use strict';
console.log("loading mqtt-test module");

var MqttTest = class MqttTest {
    constructor() {
      console.log("instanciating mqtt module");
      this.mqtt = require('mqtt');
      this.client  = this.mqtt.connect('mqtt://broker');
      var fs = require('fs');
      var data = {};

      function base64_encode(file) {
          // read binary data
          var bitmap = fs.readFileSync(file);
          // convert binary data to base64 encoded string
          return new Buffer(bitmap).toString('base64');
      }

      var base64str = base64_encode('msg-1-fc-40.jpg');
      data.message = base64str;
      data.topic = 'message/topic';
      var jsonMessage = JSON.stringify(data.message);
      if(jsonMessage.length >= 2048){
        var messageChunks = this.chunkSubstr(jsonMessage, 2048);
        var messageId = Math.random().toString(36).substr(2, 16);
        var chunkNumber = 0;
        var totalChunks = messageChunks.length;
        console.log('totalChunks'+totalChunks);
        messageChunks.forEach(function(messageChunk) {
          var chunk = {data: {}};
          chunk.partial = {};
          chunk.partial.number = chunkNumber;
          chunk.partial.id = messageId;
          chunk.partial.total = totalChunks;
          chunk.data = messageChunk;
          chunk.topic = jsonMessage.topic;
          this.client.publish(data.topic, JSON.stringify(chunk), {'qos': 2});
          chunkNumber++;
        }, this);
      }
      else{
        this.client.publish(data.topic, jsonMessage, {'qos': 2});
      }

      this.client.on('connect', function () {
        console.log("MQTT connected");
      }.bind(this));
      console.log("finished instanciating mqtt module");
    }

    chunkSubstr(str, size) {
      var numChunks = Math.ceil(str.length / size),
          chunks = new Array(numChunks);

      for(var i = 0, o = 0; i < numChunks; ++i, o += size) {
        chunks[i] = str.substr(o, size);
      }

      return chunks;
    }
};

var myMqttTest = new MqttTest();
console.log("loaded mqtt-test module");