I did a bit of testing when I was writing PushEx. We didn’t have the need for 500k clients, but in the high 10s of thousands.
A few recommendations based on that:
- Presence ran into issues when I had large topics (500+ clients). It would time-out on the track call. I was able to switch to Tracker and get it a bit higher (maybe 1000-2000 clients). Ultimately, I decided to remove tracking large topics and just assumed they had connected clients. It depends on your use case
- Use Tracker if you don’t need to broadcast the diff to every client. You will get better performance because you’re doing less work. You can still send out the diffs manually as needed.
- Tracker was generally well-behaved for smaller topics (< 50 clients). So the performance characteristics are going to vary wildly based on your topic configuration
