I've only run it as part of stress tests when evaluating it for a new application, and I found it to be a pleasure to work with.
We did push it to more than 10k partitions, but I honestly don't remember how that affected it; that's when I discovered that partitions cannot be dynamically rebalanced, which meant we'd have to change the way we would use it.
Interestingly, we also did a similar test with NATS JetStream, which did start struggling around 10,000 consumers. (A consumer in NATS is similar to a partition, as it has its own Raft group.) What I tried to do with JetStream goes against the grain a bit, mind you; I still think it's an excellent piece of software.
We have some great work coming that allows lighter weight consumers to scale to that level and beyond. Happy to chat with folks on how we can make that work today.
We did push it to more than 10k partitions, but I honestly don't remember how that affected it; that's when I discovered that partitions cannot be dynamically rebalanced, which meant we'd have to change the way we would use it.
Interestingly, we also did a similar test with NATS JetStream, which did start struggling around 10,000 consumers. (A consumer in NATS is similar to a partition, as it has its own Raft group.) What I tried to do with JetStream goes against the grain a bit, mind you; I still think it's an excellent piece of software.