Apache Cassandra — threads and memory

The talk is about Apache Cassandra database internals, how does it look like from a Java developer point of view:

1. How threads are organized, what thread pools exist, and how to monitor them. Does Cassandra use Disruptor?
2. What kind of multithreading problems are solved in Apache Cassandra?
3. Memory. Where are data stored in memory within Apache Cassandra: heap or off-heap? What data structures are used, how much memory is consumed, how to monitor it?

The talk will be based on the recently released Apache Cassandra 4.0. The target audience is Java developers who develop this kind of system, as well as those who operate Apache Cassandra and want a better understanding of its internals.