Chris Seaton @ VMSS16: JRuby+Truffle: Why it’s Important to Optimise the Tricky Parts

Chris Seaton gave this talk recently about JRuby+Truffle and some specifics about how it optimises so well compared to other Ruby implementations. [VIDEO] Previous discussion [LINK]

I hear the Truffle+Graal combination is getting very good results about Ruby. Here is video about it (pointed to the missing-method example): [1] They're hitting 35x in some benchmarks [2]. Most benefits being in workloads where Ruby has to continuously talk to C; the result-passing part gets compiled away. It is available in Java 9, if I'm not mistaken. LLVM IR bytecode ingestion is in preparations too [3]. [1] [VIDEO] [2] [LINK] [3] [LINK]

> I understand that a JIT engine cant do this, due to speed. Most serious JIT engines do! For example V8, LuaJIT, Graal, C2. > But would be surprised that a LLVM compiler with a custom-designed heuristic for specific optimizations cant manage this. Rubinius for example tried writing custom optimisations like you're describing and didn't get very far. LLVM is not designed for these kind of optimisations - it understands memory reads and writes, not high-level semantic information about arrays and objects. In practice, it just doesn't seem to work. As I say I think it's a bare minimum for making a dynamic language genuinely fast. I gave a lecture about this [VIDEO] .