this seems truthy but isn't in practice. a lot of work, my perf optimization team @ redpanda does (yes we have a full team chasing tail latencies) is spent on CPU optimization, debouncing, amortizing costs, metadata lookups, hash tables, profilers, etc. so there is a lot of additional work after the IO layer which a decent async eventing thing can get you to get good perf.

What I mean to say is that in my experience the time spent round-tripping to Kafka is more than the time it takes Kafka to do whatever I'm asking it to do. So at least for my use-cases a faster Kafka would be of no benefit.

Now if it means I can run fewer smaller brokers that's awesome.

def. that should be the case, we have iot companies pushing us on a single pthread a a few megs of ram.

> Flink/Spark/KStreams/KTable etc.

Then it's still a bit of an untruth since all of those use RocksDB for their high-performance storage layer, which isn't in Java. You could maybe (maybe!) argue for some ergonomics (though especially hard to argue for Spark!) but performance still goes plainly to C (/ C++).

We're not talking about the systems you build on top of here. We're talking about the code. You write yourself. The fact that rocks is written in c is irrelevant to the fact that in order to use the ecosystem I'm describing you need to be on the JVM or your experience will be at best subpar.

Sure, if you ignore offloading all the hard work to a C library, we can pretend any language is as fast as any other. It's a boring conversation then though - might as well use Python...

Not to mention you still pay a real performance penalty for being unable to make direct use of RocksDB features, because Kafka is shoving a million "abstraction" and cache layers in there and you just want your your damned merge operator to apply.

I don't agree Kafka off the JVM is subpar. Kafka Streams has a lot of sharp edges from "abstractions" that aren't, Spark is a godawful developer experience and tuning it for performance is black magic for 99% of data engineers, and Flink keeps dithering about how consistent/stable baseline features like queries will be. You can stand up very good apps for a huge set of common cases just as quickly in Go or C++, and not have to deal with Kafka Streams's funny opinions about threads/tasks/consumers.