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TruffleRuby logo

A high performance implementation of the Ruby programming language. Built on GraalVM by Oracle Labs.

Getting started

There are three ways to install TruffleRuby:

You can use gem to install Gems as normal.

You can also build TruffleRuby from source, see the building instructions, and using Docker.


TruffleRuby aims to:

  • Run idiomatic Ruby code faster
  • Run Ruby code in parallel
  • Boot Ruby applications in less time
  • Execute C extensions in a managed environment
  • Add fast and low-overhead interoperability with languages like Java, JavaScript, Python and R
  • Provide new tooling such as debuggers and monitoring
  • All while maintaining very high compatibility with the standard implementation of Ruby

TruffleRuby configurations

There are two main configurations of TruffleRuby: native and JVM. It's important to understand the different configurations of TruffleRuby, as each has different capabilities and performance characteristics. You should pick the execution mode that is appropriate for your application.

TruffleRuby by default runs in the native configuration. In this configuration, TruffleRuby is ahead-of-time compiled to a standalone native executable. This means that you don't need a JVM installed on your system to use it. The advantage of the native configuration is that it starts about as fast as MRI, it may use less memory, and it becomes fast in less time. The disadvantage of the native configuration is that you can't use Java tools like VisualVM, you can't use Java interoperability, and peak performance may be lower than on the JVM. The native configuration is used by default, but you can also request it using --native. To use polyglot programming with the native configuration, you need to use the --polyglot flag. To check you are using the native configuration, ruby --version should mention Native.

TruffleRuby can also be used in the JVM configuration, where it runs as a normal Java application on the JVM, as any other Java application would. The advantage of the JVM configuration is that you can use Java interoperability, and peak performance may be higher than the native configuration. The disadvantage of the JVM configuration is that it takes much longer to start and to get fast, and may use more memory. The JVM configuration is requested using --jvm. To check you are using the JVM configuration, ruby --version should not mention Native.

If you are running a short-running program you probably want the default, native, configuration. If you are running a long-running program and want the highest possible performance you probably want the JVM configuration, by using --jvm.

At runtime you can tell if you are using the native configuration using TruffleRuby.native?.

You won't encounter it when using TruffleRuby from the GraalVM, but there is also another configuration which is TruffleRuby running on the JVM but with the Graal compiler not available. This configuration will have much lower performance and should normally only be used for development. ruby --version will mention Interpreter for this configuration.

System compatibility

TruffleRuby is actively tested on these systems:

  • Oracle Linux 7
  • Ubuntu 18.04 LTS
  • Ubuntu 16.04 LTS
  • Fedora 28
  • macOS 10.14 (Mojave)
  • macOS 10.13 (High Sierra)


  • LLVM to build and run C extensions
  • libssl for the openssl C extension
  • zlib for the zlib C extension

Without these dependencies, many libraries including RubyGems will not work. TruffleRuby will try to print a nice error message if a dependency is missing, but this can only be done on a best effort basis.

You may also need to set up a UTF-8 locale.

Current status

We recommend that people trying TruffleRuby on their gems and applications get in touch with us for help.

TruffleRuby is progressing fast but is currently probably not ready for you to try running your full Ruby application on. However it is ready for experimentation and curious end-users to try on their gems and smaller applications.

TruffleRuby runs Rails, and passes the majority of the Rails test suite. But it is missing support for Nokogiri and ActiveRecord database drivers which makes it not practical to run real Rails applications at the moment.

You will find that many C extensions will not work without modification.

Migration from MRI

TruffleRuby should in most cases work as a drop-in replacement for MRI, but you should read about our compatibility.

Migration from JRuby

For many use cases TruffleRuby should work as a drop-in replacement for JRuby. However, our approach to integration with Java is different to JRuby so you should read our migration guide.


Extensive documentation is available in doc. doc/user documents how to use TruffleRuby and doc/contributor documents how to develop TruffleRuby.


The best way to get in touch with us is to join us in, but you can also Tweet to @TruffleRuby, or email

Mailing list

Announcements about GraalVM, including TruffleRuby, are made on the graal-dev mailing list.


The main authors of TruffleRuby in order of joining the project are:

  • Chris Seaton
  • Benoit Daloze
  • Kevin Menard
  • Petr Chalupa
  • Brandon Fish
  • Duncan MacGregor


  • Thomas Würthinger
  • Matthias Grimmer
  • Josef Haider
  • Fabio Niephaus
  • Matthias Springer
  • Lucas Allan Amorim
  • Aditya Bhardwaj

Collaborations with:

And others.


See the security documentation.


TruffleRuby is copyright (c) 2013-2018 Oracle and/or its affiliates, and is made available to you under the terms of any one of the following three licenses:

  • Eclipse Public License version 1.0, or
  • GNU General Public License version 2, or
  • GNU Lesser General Public License version 2.1.

TruffleRuby contains additional code not always covered by these licences, and with copyright owned by other people. See doc/legal/ for full documentation.


TruffleRuby is a fork of JRuby, combining it with code from the Rubinius project, and also containing code from the standard implementation of Ruby, MRI.