ANNOUNCE: PQC: QuickCheck in the Age of Concurrency

Donald Bruce Stewart dons at
Thu Nov 23 23:44:09 EST 2006

PQC: QuickCheck in the Age of Concurrency

An SMP parallel QuickCheck driver

Do you:

    * Have (or want) lots of QuickCheck properties? 
    * Run them often (maybe on every darcs commit)? 
    * Tired of waiting for the testsuite to finish? 
    * Got a multi-core box with cpus sitting idle...? 
Yes? You need Parallel QuickCheck! 

PQC provides a single module: Test.QuickCheck.Parallel.  This is a
QuickCheck driver that runs property lists as jobs in parallel, and will
utilise as many cores as you wish, with the SMP parallel GHC 6.6
runtime. It is simple, scalable replacement for Test.QuickCheck.Batch.

An example, on a 4 cpu linux server, running 20 quickcheck properties.

    With 1 thread only:
        $ time ./a.out 1
        1: sort1                    : OK, 1000 tests.
        1: sort2                    : OK, 1000 tests.
        1: sort3                    : OK, 1000 tests.
        1: sort4                    : OK, 1000 tests.
        ./a.out 1 > x  18.94s user 0.01s system 99% cpu 18.963 total

    18 seconds, 99% cpu. But I've got another 3 2.80GHz processors sitting
    idle! Let's use them, to run the testsuite faster. No recompilation required.

    4 OS threads, 4 Haskell threads:
        $ time ./a.out 4 +RTS -N4 > /dev/null
        ./a.out 4 +RTS -N4 > /dev/null  20.65s user 0.22s system 283% cpu 7.349 total

    283% cpu, not bad. We're getting close to being limited by the
    length of the longest running test.

Or on a dual core macbook, thanks to Spencer Janssen for macbook data
and testing:

    1 thread:
        ./Example 1 

    2 threads:
        ./Example 2 +RTS -N2 

Get it!

    Example :

    darcs get

Happy, quick checking,

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