GCP Pub/Sub Subscription Not Receiving Messages When Using Multiple Subscribers in Node.js
I've hit a wall trying to I'm trying to debug I've spent hours debugging this and I'm working on a GCP application where I'm using Pub/Sub to decouple my microservices. I've set up a topic and multiple subscriptions to allow different services to listen for messages. However, I'm encountering an issue where only one of the subscribers seems to process messages, while the others do not receive any. Here’s a simplified version of my Node.js subscriber code: ```javascript const { PubSub } = require('@google-cloud/pubsub'); const pubsub = new PubSub(); const subscriptionName = 'my-subscription'; const timeout = 60; const subscription = pubsub.subscription(subscriptionName); const messageHandler = message => { console.log(`Received message: ${message.id}`); // Process the message message.ack(); }; subscription.on('message', messageHandler); setTimeout(() => { subscription.removeListener('message', messageHandler); console.log(`Timeout reached, listener removed`); }, timeout * 1000); ``` I’ve verified that the messages are being published correctly to the topic, and I can see them in the Pub/Sub dashboard. However, when I run multiple instances of this subscriber code (e.g., in different terminal windows), only one instance seems to process and acknowledge the messages while the others stay idle. I've checked the subscription's configuration, and it’s set to `EXCLUSIVE` delivery mode. Additionally, I’m aware that using multiple subscribers on the same subscription can lead to complications, but I expected them to process messages in parallel. I also tried using `--ack-deadline` to allow more time for message processing, but it didn't change the behavior. Here's the command I use to start each subscriber: ```bash node subscriber.js ``` What am I missing here? Is there something specific in the configuration or the design that I'm overlooking that would cause this behavior? Any tips on how to properly set up multiple subscribers for load balancing would be greatly appreciated! This is part of a larger service I'm building. Am I missing something obvious? I'm working in a Linux environment. What am I doing wrong? I've been using Javascript for about a year now. What are your experiences with this?