How do you handle Socket.IO across multiple instances?
When Socket.IO runs across multiple application instances, clients connected to different instances need a way to exchange events. A shared adapter or pub/sub mechanism such as Redis can distribute events between instances. Depending on the deployment and transport configuration, sticky sessions may also be relevant. The architecture should ensure that connection-specific state is handled appropriately when clients can move between instances.
Key Takeaways
- Multiple Socket.IO instances need shared event coordination.
- Redis is commonly used as a shared adapter/pub-sub mechanism.
- Deployment topology can determine whether sticky sessions are needed.
Knowledge Check
What can be used to distribute Socket.IO events across multiple Node.js instances?