Sure, but it’s only at large scale that you care about stuff like PGO. My experience is that even small shops care about JVM tuning.

It’s not a question of whether there are knobs to turn. It’s about the typical experience of an actual person running a JVM app versus, say, C or Go, and those experiences are quite different.

And we’re also talking about running someone else’s app. If your database queries are slow, that’s a conversation between the DBA and the devs. If you’re running some Apache app, you’re probably not talking to the devs.

In 20 years of using Java I only had one project where fine-tuning knobs was actually relevant.

Most of the time defaults just work.

Yeah, I've been a C/C++ programmer for 15+ years with heavy focus on performance, and have not once run PGO. I think it's quite often the case for C/C++ programs that you -O2 and walk away, at least for codebases that your team doesn't specifically own.

> My experience is that even small shops care about JVM tuning.

This hasn't been my experience at all after running java on production servers for over a decade.

Unlike C/C++ you do have to care about tuning at a minimum to set the memory sizes.

That said you probably can’t get very far in c/c++ without worrying about memory the whole way through. So, you only worry about tuning when writing your code.

When you run into that problem with Go you stop dead because there is nothing to do.