Comparing the C FFI overhead in various programming languages

For those wondering why luajit is faster than C/C++/Rust, that's probably because it does direct calls to the function, while C/C++/Rust go through the PLT (procedure linkage table). I don't have luajit to validate this, but changing the C test to dlsym() the symbol first and use that in the loop instead makes the test take 727ms instead of 896ms when going through the PLT on my machine. Edit: confirmed after installing luajit, got the same time as the modified…

Another major caveat to this benchmark is it doesn't include any significant marshalling costs. For example, passing strings or arrays from Java to C is much, much slower than passing a single integer. Same is going to be true for a lot (all?) of the GC'd languages, and especially true for strings when the language isn't utf8 natively (as in, even though Java can store in utf8 internally, it doesn't expose that publicly so JNI doesn't benefit)

(2021)

I really think this exemplifies the reason why Lua is so useful.