CODEWITHSUNDEEP
javascriptnode.jsrabbitmq
Dũng Nguyễn
Dũng Nguyễn

Reputation: 495

RabbitMQ: Consume item after the previous one is finished

I'm new to RabbitMQ. What I want is to execute only one item at a time, the next one will be consumed after the previous one is finished.

Here is how Consumer is created:

consumer.assertQueue(queue, { durable: true });
consumer.consume(queue, handleMessage, { noAck: false });

Here is function handleMessage:

async function handleMessage(message) {    
    console.log('handleMessage', message.content.toString());
    // wait for 1 second
    await wait(1000); 
    console.log('ACK', message.content.toString());
    consumer.ack(message);
}

The Publisher will send items like this:

publisher.sendToQueue(queue, Buffer.from('1'));
publisher.sendToQueue(queue, Buffer.from('2'));

Here is the log. It seem does not wait for the handle process to wait 1 second to finished:

handleMessage 1
handleMessage 2
ACK 1
ACK 2

What I want is:

handleMessage 1
ACK 1
handleMessage 2
ACK 2

Mean message 1 must be finished before it handle message 2. How can I do it? Thanks.

Upvotes: 0

Views: 1438

Answers (1)

menya
menya

Reputation: 1525

If you have a single queue with a single consumer, you can set the prefetch to 1.

channel.prefetch(1)

You can get more detail from RabbitMQ 's official doc:

The value defines the max number of unacknowledged deliveries that are permitted on a channel. Once the number reaches the configured count, RabbitMQ will stop delivering more messages on the channel unless at least one of the outstanding ones is acknowledged

Upvotes: 1

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