alt Hacker News> Hotspot is the choice for high performance programs. Approaching its performance even with C++ requires a dedicated team of experts.
It's very surprising to hear you say this, as it's so contrary to my experience.
From the smallest programs (Computer Language Benchmarks Game) to pretty big programs (web browsers), from low-level programs (OS kernels) to high-level programs (GUI Applications), from short-lived programs (command-line utilities) to long-lived programs (database servers), it's hard to think of a single segment where even average Java programs will out-perform average C, C++, or Rust programs.
I hadn't heard of QuestDB before, but it sounds like it's written in zero-GC Java using manual memory management. That's pretty unusual for Java, and would require a team of experts to pull off, I'd think. It also sounds like it drops to C++ and Rust for performance-critical tasks.
It's a statement of my experience in the performance achieved in practice by real developers who lack dedicated language support teams. And even the ones who enjoy dedicated language support teams. I could point to gRPC. gRPC-Java is slapping gRPC-C++ sideways. Why is that? Because when a codebase is increasingly complex, the C-style lifetime management becomes too difficult for developers to ponder, and they revert to relying on the slower features of the language platform, like reference counting smart pointers.
I think hybrid implementations, where a project enjoys the beneficial aspects of the language runtime at large, but delegates small, critical functions to other languages, makes sense. That keeps the C, C++, or Rust stuff contained to boundaries that are ponderable and doesn't let those language platforms dictate the overall architecture of the program.