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NOTE: This page is a work-in-progress!

(incomplete) TODO list

  • add more positive points (e.g. what's already implemented)
  • discuss the page design
  • define relationship to related pages (e.g. How to help)
  • insert more links
  • review
  • link this page from the sidebar once it's done

General project status

Jikes RVM is currently the most popular platform for virtual machine research. This popularity is reflected in the particpation on the mailing lists where most questions can be answered.

Memory management research is a particular strength of the Jikes RVM. The Memory Management Toolkit (MMtk) provides a well-rounded selection of garbage collectors and the compiler replay feature enables researchers to control mutator variation. The MMTk test harness can be used to test collectors.

In contrast to this, the compilers are currently a weak spot in the Jikes RVM. For example, the Static Single Assignment (SSA) form in the compilers is currently disabled because of bugs.

The Jikes RVM is not state-of-the-art in some areas. In particular, Jikes RVM currently does not provide 64-bit Intel Support. Another big limitation is the lack of support for the OpenJDK class library. The project has received community contributions to improve those shortcomings but the code is not yet in the mainline. The Jikes RVM would also profit from efforts directed to stability improvements and bugfixes. For example, Jikes RVM currently cannot run all of the Dacapo 9.12 benchmarks.

The Jikes RVM team aims to provide at least one release every year.

Note: The information on this page refers to the status in the code repository and not to the status in the current release.

Near-term goals

  • Add support for the OpenJDK class libraries
  • Add Intel 64-bit support
  • Get DaCapo 9.12 running on the Jikes RVM

Preliminary long-term goals (still need further discussion)

  • Improve stability
  • Improve compliance with JVM spec
  • Write unit tests for all classes
  • Improve and extend test suites
  • add support for relevant new platforms (ARM?)

Detailed project status

Community

  • Jikes RVM has a large community in its intended audience (researchers)
  • Core team consists wholly of volunteers: no paid developers
  • Jikes RVM is currently not packaged for any major distribution

Memory Management

  • GenImmix (the default collector) is very stable
  • The other collectors are reasonably stable but have some bugs (see regression tests)
  • Notable omissions in the collector choices include Baker-style collectors, the Compressor and on-the-fly collectors

Runtime

  • Jikes RVM currently does not follow the JVM specification
  • Jikes RVM lacks an interpreter
  • strictfp is not implemented
  • JMX is not implemented
  • JVMTI is not implemented

Adaptive Optimization System

  • the AOS provides a good level of control via compiler replay
  • the AOS provides clear extension points
  • Jikes RVM currently uses only one compilation thread at runtime and the current AOS model does not support multiple compilation threads
  • the provided AOS models do not support Feedback-Directed Optimizations

Compiler

  • SSA form is disabled. Scalar SSA form may be fixable; Heap SSA form is probably too broken
  • Many optimizations are disabled because they rely on SSA or are considered too buggy
  • No support for polyhedral model
  • Bound check elimination is unimplemented
  • Java Memory Model (JMM) is not correctly implemented

Infrastructure

  • Need access to PowerPC machines for all team members
  • Regression tests are run regulary. The results are displayed with Cattrack. Cattrack needs to be updated to the latest versin of Ruby on Rails.
  • Currently no infrastructure for CI: Core team members need to ensure they run the pre-commit tests themselves.
  • Currently no code review tools in use
  • Some unit tests (via JUnit) exist but most classes don't have unit tests
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