Eclipse OMR

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What Is Eclipse OMR?

The Eclipse OMR project is a set of open source C and C++ components that can be used to build robust language runtimes that support many different hardware and operating system platforms.

Our current components are:

  • gc: Garbage collection framework for managed heaps
  • compiler: Components for building compiler technology, such as JIT compilers.
  • jitbuilder: An easy to use high level abstraction on top of the compiler technology.
  • port: Platform porting library
  • thread: A cross platform pthread-like threading library
  • util: general utilities useful for building cross platform runtimes
  • omrsigcompat: Signal handling compatibility library
  • omrtrace: Tracing library for communication with IBM Health Center monitoring tools
  • tool: Code generation tools for the build system
  • vm: APIs to manage per-interpreter and per-thread contexts
  • example: Demonstration code to show how a language runtime might consume some Eclipse OMR components
  • fvtest: A language-independent test framework so that Eclipse OMR components can be tested outside of a language runtime

What's the goal?

The long term goal for the Eclipse OMR project is to foster an open ecosystem of language runtime developers to collaborate and collectively innovate with hardware platform designers, operating system developers, as well as tool and framework developers and to provide a robust runtime technology platform so that language implementers can much more quickly and easily create more fully featured languages to enrich the options available to programmers.

It is our community's fervent goal to be one of active contribution, improvement, and continual consumption.

We will be operating under the Eclipse Code of Conduct to promote fairness, openness, and inclusion.

Who is using Eclipse OMR?

  • The most comprehensive consumer of the Eclipse OMR technology is the Eclipse OpenJ9 Virtual Machine: a high performance, scalable, enterprise class Java Virtual Machine implementation representing hundreds of person years of effort, built on top of the core technologies provided by Eclipse OMR.
  • The Ruby+OMR Technology Preview has used Eclipse OMR components to add a JIT compiler to the CRuby implementation, and to experiment with replacing the garbage collector in CRuby.
  • A SOM++ Smalltalk runtime has also been modified to use Eclipse OMR componentry.
  • An experimental version of CPython using Eclipse OMR components has also been created but is not yet available in the open. (Our focus has been dominated by getting this code out into the open!)

What's the licence?

License License

All Eclipse OMR project materials are made available under the Eclipse Public License 2.0 and the Apache 2.0 license. You can choose which license you wish to follow. Please see our LICENSE file for more details.

What's being worked on?

There are some active contribution projects underway right now:

  • Documentation: code comments are great, but we need more overview documentation so we're writing that
  • FAQ: Frequently Asked Questions from real people's questions (request: ask questions!)
  • Beginner issues: relatively simple but useful work items meant for people new to the project.
  • diag: more diagnostic support for language runtimes to aid developers and users
  • hcagent: the core code for the IBM Health Center agent for interfacing to a runtime
  • gc: adding generational and other GC policies

How Do I Interact With the Community?

  • Join the Eclipse OMR developer community mailing list. The community typically uses this list for project announcements and administrative discussions amongst committers. Questions are welcome here as well.

  • Join the Eclipse OMR community Slack workspace. You can join channels that interest you, ask questions, and receive answers from subject matter experts.

  • Ask a question or start a discussion via a GitHub issue.

How Do I Use it?

How to Build Standalone Eclipse OMR

The best way to get an initial understanding of the Eclipse OMR technology is to look at a 'standalone' build, which hooks Eclipse OMR up to the its testing system only.

Basic configuration and compile

To build standalone Eclipse OMR, run the following commands from the top of the source tree. The top of the Eclipse OMR source tree is the directory that contains

# Generate autotools makefiles with SPEC-specific presets
make -f SPEC=linux_x86-64 OMRGLUE=./example/glue

# Build

# Run tests (note that no contribution should cause new test failures in "make test")
make test

Run make -f help for a list of configure makefile targets. Run make help for a list of build targets.

Building Eclipse OMR on Windows

A shell script interpreter, such as bash, is required to run configure.

How to Configure with Custom Options

Run ./configure --help to see the full list of configure command-line options.

To run configure using both SPEC presets and custom options, pass the EXTRA_CONFIGURE_ARGS option to

For example, to disable optimizations, run configure like this:

# Example configure
make -f SPEC=linux_x86-64 OMRGLUE=./example/glue 'EXTRA_CONFIGURE_ARGS=--disable-optimized' clean all

To disable building fvtests, run configure like this:

# Example configure disabling fvtests
make -f SPEC=linux_x86-64 OMRGLUE=./example/glue 'EXTRA_CONFIGURE_ARGS=--disable-fvtest' clean all

Note that the clean target of deletes the header files and makefiles generated by configure. Invoking the clean all targets ensures that the header files and makefiles are regenerated using the custom options.

The minimal invocation of configure is:

# Basic configure example
$ ./configure OMRGLUE=./example/glue

Where can I learn more?

Presentations about Eclipse OMR

Blog Posts about OMR technologies

(c) Copyright IBM Corp. 2016, 2018

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