Kafka Producer在收到新消息时拍摄“错误：Producer未连接”

Question

考虑Express服务器+ Kafka Producer：

var express = require('express');
var app = express();

var Kafka = require('node-rdkafka');

// Kafka

var producer = new Kafka.Producer({
  //'debug' : 'all',
  'metadata.broker.list': 'localhost:9092',
  dr_cb: true, //delivery report callback
});

var topicName = 'test';

//logging debug messages, if debug is enabled
producer.on('event.log', function (log) {
  console.log(log);
});

//logging all errors
producer.on('event.error', function (err) {
  console.error('Error from producer');
  console.error(err);
});

//counter to stop this sample after maxMessages are sent
var counter = 0;
var maxMessages = 10;

producer.on('delivery-report', function (err, report) {
  console.log('delivery-report: ' + JSON.stringify(report));
  counter++;
});

//Wait for the ready event before producing
producer.on('ready', function (arg) {
  console.log('producer ready.' + JSON.stringify(arg));

  for (var i = 0; i < maxMessages; i++) {
    var value = Buffer.from('value-' + i);
    var key = 'key-' + i;
    // if partition is set to -1, librdkafka will use the default partitioner
    var partition = -1;
    var headers = [{ header: 'header value' }];
    producer.produce(topicName, partition, value, key, Date.now(), '', headers);
  }

  //need to keep polling for a while to ensure the delivery reports are received
  var pollLoop = setInterval(function () {
    producer.poll();
    if (counter === maxMessages) {
      clearInterval(pollLoop);
      producer.disconnect();
    }
  }, 1000);
});

producer.on('disconnected', function (arg) {
  console.log('producer disconnected. ' + JSON.stringify(arg));
});

//starting the producer
producer.connect();

// End Kafka

app.get('/', (req, res) => res.send('Ready to send messages!'));

app.post('/:maxMessages', function (req, res) {
  if (req.params.maxMessages) {
    var maxMessages = parseInt(req.params.maxMessages);
    console.log(`Got it ... ${maxMessages}`);
    for (var i = 0; i < maxMessages; i++) {
      var value = new Buffer.from('MyProducerTest - value-' + i);
      var key = 'key-' + i;
      // if partition is set to -1, librdkafka will use the default partitioner
      var partition = -1;
      producer.produce(topicName, partition, value, key);
    } // end for
    res.status(200).json({
      success: true,
    });
  } // end if

  console.log('Out of IF ...');
}); // end app.post()

app.listen(3000, () => console.log('Example app listening on port 3000!'));

和消费者：

var Transform = require('stream').Transform;

var Kafka = require('node-rdkafka');

var stream = Kafka.KafkaConsumer.createReadStream(
  {
    'metadata.broker.list': 'localhost:9092',
    'group.id': 'librd-test',
    'socket.keepalive.enable': true,
    'enable.auto.commit': false,
  },
  {},
  {
    topics: 'test',
    waitInterval: 0,
    objectMode: false,
  }
);

stream.on('error', function (err) {
  if (err) console.log(err);
  process.exit(1);
});

stream.pipe(process.stdout);

stream.on('error', function (err) {
  console.log(err);
  process.exit(1);
});

stream.consumer.on('event.error', function (err) {
  console.log(err);
});


console.log('Waiting to consume...');

当我向http://localhost:3000/20发出邮递员POST请求时，我进入生产者屏幕：

Error: Producer not connected
    at Producer.produce (C:\Development-T410\Kafka\node_modules\node-rdkafka\lib\producer.js:125:11)
    at C:\Development-T410\Kafka\app.js:79:16
    at Layer.handle [as handle_request] (C:\Development-T410\Kafka\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Development-T410\Kafka\node_modules\express\lib\router\route.js:137:13)
    at Route.dispatch (C:\Development-T410\Kafka\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (C:\Development-T410\Kafka\node_modules\express\lib\router\layer.js:95:5)
    at C:\Development-T410\Kafka\node_modules\express\lib\router\index.js:281:22
    at param (C:\Development-T410\Kafka\node_modules\express\lib\router\index.js:354:14)
    at param (C:\Development-T410\Kafka\node_modules\express\lib\router\index.js:365:14)
    at Function.process_params (C:\Development-T410\Kafka\node_modules\express\lib\router\index.js:410:3)

关于消费者：

LibrdKafkaError: Local: Broker transport failure
    at Function.createLibrdkafkaError [as create] (C:\Development-T410\Kafka\node_modules\node-rdkafka\lib\error.js:411:10)
    at C:\Development-T410\Kafka\node_modules\node-rdkafka\lib\client.js:350:28 {
  origin: 'local',
  message: 'broker transport failure',
  code: -195,
  errno: -195
}

为什么？