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A collection of different packages for CAS based data structures.
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BenchThroughput @ ec37bba

Contents of this Repository

This is a multi-package repository. The following directories correspond to the following packages:

CAS            - IORefCAS
AbstractDeque  - abstract-deque
MichaelScott   - lockfree-queue
ChaseLev       - chaselev-deques
MegaDeque      - mega-deque

Please see the .cabal files for descriptions of each package. Here's a brief summary:

  • CAS - Compare and swap operations for
  • AbstractDeque - abstract interface for single and double ended queues, plus reference implementation in pure Haskell
  • MichaelScott - classic Michael & Scott algorithm for single ended queues
  • ChaseLev - Work-stealing "1.5" ended deques.
  • MegaDeque - a package that picks the best implementation for the interface constraints, which are expressed at the type level.

How to Test and Install

First, to really use compare-and-swap based data structures, you should be using GHC 7.4.1 or later. These libaries will be force to "fake it" on earlier versions of GHC.

You can install all of the packages in your user's .cabal directory with the following command:


You may also want to build the tests at the same time:

./ --enable-tests

There are currently [2012.02.29] some problems with cabal failing to automatically install dependencies for tests (as opposed to libraries). You may have to manually install some packages via cabal (e.g. test-framework-HUnit).

If you take a look at that script, you'll notice you can also configure which executables for cabal and ghc it uses, for example:

GHC=ghc-7.4.1 CABAL=cabal-0.10.2 ./ --enable-tests

Next, you can run the tests like this:


That test should complete successfully with a zero exit code.

Note that if you have trouble building test-suites through cabal, you can build them manually with GHC using a command like the following:

cd MichaelScott/
ghc-7.4.1 -O2 -threaded -rtsopts Test.hs -o Test.exe

Building with Profiling for debugging:

ghc-7.4.1 -prof -osuf=o_p -O2 -threaded -rtsopts Test.hs -o Test.exe

You might have to reinstall some of the dependencies with profiling enabled:

cabal install -p hostname xml regex-base regex-posix ansi-terminal ansi-wl-pprint test-framework test-framework-hunit --reinstall           

Reinstalling with profiling can be REALLY annoying once the libraries are already installed. For example, if you forget a dependency above it will complete most of the compile, giving you the "profiling version not available" error only later on, resulting in a quadratic compilation process as you reinstall, add one more dep, reinstall, repeat.


  • [2012.02.29] The tests for abstract-deque currently stack overflow, but pass with an increased (100M) stack size.

  • [2012.02.29] ChaseLev deques exhibit nondeterministic failures still. Hopefully this is due to a bug in the implementation and not further problems in Haskell's CAS (there was a fix AFTER ghc-7.2.1).


    • It would be nice to add a binding to TBB concurrent queues or other foreign implementations (for storable types).

    • Test on windows. (It hasn't been tried.)

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