Duncan Macgregor speaks with Wes Reisz about the work being done on the experimental Graal Compiler. He talks about the use cases and where the new JIT compiler excels really well (compared to C2). In addition, Duncan talks about the relationship of Graal to Truffle. The two then discuss a language Duncan works on at OracleLabs (TruffleRuby) that is being implemented on the stack. Finally, the podcast wraps with a discussion of Project Loom and its relationship to TruffleRuby and Graal.

Why listen to this podcast:

- Graal is a replacement for the JVM’s C2 JIT compiler. It was tracked with JEP 295 (Ahead-of-Time Compilation) and included in Java 9. As of Java 10, Graal is experimental for the Linux x64 platform.

- Graal is written in Java and excels at implementing code that takes a functional approach to solving problems (such as Scala). It can also offer improvements / optimizations for other languages (including other non-traditional JVM languages such as C and Ruby).

- Truffle is a language implementation framework used my Graal. The idea is rather than having to write a compiler for your language, you can write an interpreter. This gives you the ability to write specializations at a higher level of abstraction that yields performance and better understanding.

- Truffle’s architecture and design allows things like allowing unrelated languages to do interop, garbage collection, and types.

- TruffleRuby and JRuby started off with a lot of shared code. They’ve branched and JRuby today focuses on integration with other Java classes. It compiles to bytecode and then relies on the C2 JIT to run on the JVM. TruffleRuby doesn’t try to compile to Java classes and only uses the Truffle framework to compile the things it needs. TruffleRuby is able to use most of native Ruby.

- Project Loom is a project that aims to add one shot delimited continuations to the JVM. It leverages fibers (a much lighter concurrency primitive than threads) and can literally run millions of them.