卡夫卡消费者在暂停和恢复后不消费消息

Question

我正在使用这个node-rdkafka库来实现带有消费者暂停和恢复方法的节点 kafka 来处理背压。 我创建了一个小演示，我可以在其中pause the consumer并resume the consumer ，但问题是在resume the consumer之后它会停止消费消息。

这是我的代码。

const Kafka = require('node-rdkafka');
const topic = 'create_user_channel';
const log_divider = '-----------------------------------';
const consumer = new Kafka.KafkaConsumer({
    'group.id':'gsuite_consumer',
    'metadata.broker.list': '*******',
    'sasl.mechanisms': 'PLAIN',
    'sasl.username': '********',
    'sasl.password': '********',
    'security.protocol': 'SASL_SSL',
    'enable.auto.commit':false
}, {});

// Connect the consumer.
consumer.connect({timeout: "1000ms"}, (err) => {
    if (err) {
        console.log(`Error connecting to Kafka broker: ${err}`);
        process.exit(-1);
    }

    console.log("Connected to Kafka broker");
});

consumer.on('disconnected', (args) => {
    console.error(`Consumer got disconnected: ${JSON.stringify(args)}`);
});

let max_queue_size = 3;
let current_queue = [];
let is_pause = false;
// register ready handler.
consumer.on('ready', (arg)=>{
    console.log('consumer ready.' + JSON.stringify(arg));
    console.log('Consumer is ready');
    consumer.subscribe([topic]);
    setInterval(function() {
        console.log('consumer has consume on :'+timeMs());  
        consumer.consume();
      }, 1000);
});

consumer.on('data',async (data)=>{
    console.log('************consumer is consuming data***********:'+timeMs());
    if(!is_pause) {
        is_pause = true;
        if(data && typeof data !== 'undefined') {
            try {
                console.log('consumer has received the data:'+timeMs());
                consumer.pause([topic]);
                console.log('consumer has pause the consuming:'+timeMs());
                await processMessage(data);
                console.log('consumer is resumed:'+timeMs());
                consumer.resume([topic]);
                console.log(log_divider);
                is_pause = false;
            } catch(error) {
                console.log('data consuming error');
                console.log(error);
            }
        } else {
            is_pause = false;
        }
    }
});

async function processMessage(data) {
   // await print_bulk(data);
    await processData(0,data);
}

async function print_bulk(data) {
    for(var i=0;i<data.length;i++) {
        await processData(i,data[i]);
    }
}


/**
 * Wait specified number of milliseconds.
 * @param ms
 */
async function wait(ms) {
    console.log('wait for the 3 sec');
    return new Promise((resolve) => setTimeout(resolve, ms));
}

var timeMs = ()=> {
    var d = new Date();
    var h = addZero(d.getHours(), 2);
    var m = addZero(d.getMinutes(), 2);
    var s = addZero(d.getSeconds(), 2);
    var ms = addZero(d.getMilliseconds(), 3);
    return h + ":" + m + ":" + s + ":" + ms;
}

var addZero = (x, n)=> {
    while (x.toString().length < n) {
        x = "0" + x;
    }
    return x;
}
async function processData(i,m) {
    if (m) {
        console.log('processing a data start:'+timeMs());
        console.log('Received a message:');
        console.log('  message: ' + m.value.toString());
        console.log('  key: ' + m.key);
        console.log('  size: ' + m.size);
        console.log('  topic: ' + m.topic);
        console.log('  offset: ' + m.offset);
        console.log('  partition: ' + m.partition);
        consumer.commitMessage(m);
    }
    await wait(3000);
    console.log('process a data completed:'+timeMs());
    // delete current_queue[i];
    // console.log('after delting lenght of current queue:'+current_queue.length);
    // console.log(log_divider);
    return true;
}

任何人都可以帮助我，恢复消费者时我做错了什么？ 当我启动消费者时，它只收到一条消息，并且在恢复后仍然不消费任何进一步的消息。

Answer 1

我已经弄清楚了这个问题。 除了consumer.pause()和consumer.resume()方法，我还需要使用consumer.assignments()方法。

所以会是这样

consumer.pause(consumer.assignments());
consumer.resume(consumer.assignments());