WHAT

Kafka broker has many thread number related configs, that is:

• num.network.threads -> default to 3
• num.io.threads -> default to 8
• num.replica.fetchers -> default to 1 (split out in  MGDSTRM-9196)
• num.recovery.threads.per.data.dir -> default to 1 (split out in MGDSTRM-9195)
• log.cleaner.threads -> default to 1
• background.threads -> default to 10

It looks like the RHOSAK doesn't override any of these configs. But some default values for them are too conservative, ex: num.recovery.threads.per.data.dir is default to 1, which will only have one thread to do log recovery, and let other CPUs idle. Other example is like num.replica.fetchers is also default to 1, but if we increase it, it'll improve the throughput of the follower replication.

WHY

Improve the performance 

HOW

Run benchmark tests to find out the best configuration for RHOSAK