pulsar

Pulsar has some limits with the maximum number of topics per namespace (<https://github.com/apache/pulsar/issues/15254|PIP-157 contains some details>). One way to address this is to ensure that you spread out topics across multiple namespaces.
There are some challenges with Pulsar operations when running with a large amount of topics. It might be worth considering a design where the number of topics could be reduced. Each solution does have different tradeoffs.

Here's a test tool that you can modify / reuse for creating a large number of topics for testing Pulsar with a large number of topics yourself: <https://github.com/lhotari/pulsar-playground/blob/master/src/main/java/com/github/lhotari/pulsar/playground/TestScenarioCreateTopics.java>