You make it sound like Java is neck-and-neck with C++ in general. There are definitely cases where naive Java is faster than naive C++, but those cases are infrequent. Java is generally in the ballpark of 1/2 C++ speed alongside Go and C# in the general case.
> W.R.T. AOT vs JIT, as others are pointing out, Graal is a compiler that can execute in both modes, i.e. it's a comparable compiler. JITC is about a 20% win for relatively static languages like Java and can be massively larger (like 4000%+) for other languages like JavaScript or Ruby. In fact the nature of very dynamic languages like Ruby or Python or JavaScript mean there's little point trying to AOT compile them at all because there'd be almost no optimisations you could safely do ahead of time.
It seems like you mistook my point for "AOT makes things fast and should be used everywhere" or "JIT is fundamentally slower than AOT"; my only point was that the JVM specifically isn't faster than AOT languages nor is it faster than AOT Java because of JIT specifically (which was how I interpreted jahewson's comment above). It sounds like I agree with you--Graal seems really promising and JIT is pretty great, especially for dynamic languages. :)
Well, C++ is such a flexible language that it's hard to say what general C++ code looks like. I'd say I'd expect Java to either match or even beat C++ for general "business code" which is pretty vague but is typified by lots of layers of abstraction, lots of data transformation, hash maps, string manipulation etc. Modern compilers like Graal are very good at analyzing and removing abstraction overhead. I'd expect C++ to stomp Java for any sort of numerics work, media codecs, 3D engines, things like that.
my only point was that the JVM specifically isn't faster than AOT languages nor is it faster than AOT Java because of JIT specifically
Hmm, but is there such a thing as an AOT language? You can interpret or JIT compile C and you can interpret, JIT or AOT compile Java too.
I think it's clearly the case that JITC Java is faster than AOT Java. It was maybe unclear for a long time but Graal and SubstrateVM let us compare now. You pay a big performance hit to use a VM-less AOT Java compile. Java is sort of a half-way house between a really dynamic language and a really static language.... it's got dynamic aspects and also static aspects.
> Hmm, but is there such a thing as an AOT language? You can interpret or JIT compile C and you can interpret, JIT or AOT compile Java too.
You're right that my language was imprecise, but my point stands. JVM does't make Java faster than popular AOT implementations of (for example) Rust or C++ or C, and JVM is almost certainly faster than AOT Java implementations because of decades of optimizations, not because JIT is inherently better than AOT.
> I think it's clearly the case that JITC Java is faster than AOT Java. It was maybe unclear for a long time but Graal and SubstrateVM let us compare now.
Graal is shaping up to be a real game changer, but it's unproven and it's exceptional among JIT implementations. If Graal is all that it's cracked up to be, I wouldn't be surprised if there is a time when all popular JIT implementations perform like Graal, but until such a time, JIT alone doesn't have any clear performance advantages over AOT in general.
> W.R.T. AOT vs JIT, as others are pointing out, Graal is a compiler that can execute in both modes, i.e. it's a comparable compiler. JITC is about a 20% win for relatively static languages like Java and can be massively larger (like 4000%+) for other languages like JavaScript or Ruby. In fact the nature of very dynamic languages like Ruby or Python or JavaScript mean there's little point trying to AOT compile them at all because there'd be almost no optimisations you could safely do ahead of time.
It seems like you mistook my point for "AOT makes things fast and should be used everywhere" or "JIT is fundamentally slower than AOT"; my only point was that the JVM specifically isn't faster than AOT languages nor is it faster than AOT Java because of JIT specifically (which was how I interpreted jahewson's comment above). It sounds like I agree with you--Graal seems really promising and JIT is pretty great, especially for dynamic languages. :)