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  • October 2009
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gpars – trials and tribulations

Posted by gdjsky01 on 2009/10/10

I am trying to get gpars (formerly known as gparallelizer) to simply run it’s demos. I thought that would be a great introduction to gpars and the use cases it can solve. Needless to say, either I am not so swift, or its harder that I imagined it would be. So far I failed miserably on Mac OS-X with Java 1.6 (from Apple of course) and Groovy 1.6.5 so I thought I would start from scratch on a native Windows XP box.


  • I downloaded and installed Java 1.6. Here is what I see at the command prompt
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Client VM (build 14.2-b01, mixed mode, sharing)
  • I downloaded and installed Groovy 1.6.5. Just took all the defaults.
C:\Dev\gparallelizer\samples>groovy --version
Groovy Version: 1.6.5 JVM: 1.6.0_16

Ok! So far so good. So now I go to the gpars site. Now I hit my first snag. This snag is common to Mac and Windows. The download link is not. Not a link that is. Drats. I don’t want to build from source. So I head to the old Google Code Site because there I can get the gparallelizer 0.8.4 jar. Which I do. I install it into the groovy lib directory… this might be a mistake, but with no other guidance, I took a chance.

While at the old Google Code Site I also grab version 0.8.4 of the samples. Now I should be stylin’

I tried this:

C:\Dev\gparallelizer\samples>groovy DemoParallelEnhancer.groovy
Caught: java.lang.NoClassDefFoundError: jsr166y/forkjoin/ForkJoinTask
at org.gparallelizer.ParallelEnhancer.class$(ParallelEnhancer.groovy)
at org.gparallelizer.ParallelEnhancer.$get$$class$org$gparallelizer$actors$pooledActors$FJPool(ParallelEnhancer.groovy)
at org.gparallelizer.ParallelEnhancer.<clinit>(ParallelEnhancer.groovy:40)
at org.gparallelizer.samples.DemoParallelEnhancer.class$(DemoParallelEnhancer.groovy)
at org.gparallelizer.samples.DemoParallelEnhancer.$get$$class$org$gparallelizer$ParallelEnhancer(DemoParallelEnhancer.groovy)

Ok so things are still complicated. 😀 So what’s JSR-166 I ask? Concurrency Utilities. I sorta gathered something like that from the ForkJoin thing. Well I downloaded from here. Ah well no… see that’s packaged as

C:\Dev\gparallelizer\samples>jar tvf "\Program Files\Groovy\Groovy-1.6.5\lib\jsr166y.jar"
 0 Tue Oct 06 15:36:08 PDT 2009 META-INF/
 102 Tue Oct 06 15:36:06 PDT 2009 META-INF/MANIFEST.MF
 0 Tue Oct 06 15:36:06 PDT 2009 jsr166y/
 1096 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool$1.class
 912 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool$DefaultForkJoinWorkerThreadFactory.class
 305 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool$ForkJoinWorkerThreadFactory.class
 1101 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool$InvokeAll.class
 306 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool$ManagedBlocker.class
 1308 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool$WaitQueueNode.class
 28273 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinPool.class
 1096 Tue Oct 06 15:36:06 PDT 2009 jsr166y/ForkJoinTask$1.class

See it’s jsr166y/ForkJoinTask not jsr166y/forkjoin/ForkJoinTask

So I figured, the gparallelizer maybe was compiled against a different version. Two of the four top level demos ran, lets try Actors.

C:\Dev\gparallelizer\samples\actors>groovy DemoLoadBalancer.groovy
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed,
General error during semantic analysis: Type ActorMessage not present

So that’s where I am right now.

Some Mac OS-X notes as well.

Most of the time I work on a MacBook Pro. All day I tinkered with gpars. On the Mac I did a GIT on src and tried to use the gradlew program. But the process hung at :compileTests and eventually (no matter how much heap I gave it with JAVA_OPTS and -XmxNNNNm) it would alway run out of heap space. I could get the assemble goal to run as it skips the tests.  Then I wound up with a 0.9-SNAPSHOT jar. But it acted strangely on the demos as well. For example the DemoMashupsWithMethods.groovy would printout “Starting download from XXXXX” and exit. Nothing else. Just exit. The Mac is running Apple’s latest 1.6 JVM and Groovy 1.6.5.

Now I know this is a pretty new item so I am not too worried. I hope maybe I can talk to folks about this at SpringOne 2GX. My use case is to break N sequential SOAP web service calls into N parallel calls joining the results. I also want to introduce groovy into production and this is finally a great use case if I can make it work. Simple, Groovy, and not introducing a whole new language which could meet with a lot more resistance (like Scala).  The point is to make more efficient use of the service tier.

3 Responses to “gpars – trials and tribulations”

  1. Vaclav said

    Thanks for the reply. But I am sure I am using 1.6.5 of groovy. It is the only Groovy on the machine. 🙂 Oh Wait! Di d you mean I need a gpars COMPILED with 1.6.5? Where can I get that? My JAR came from Google Code. Or do I need to get the 0.8.4 code?

    I will get the correct 166y jar and add to the blog..
    Best wishes

    Thanks for trying out gpars. The place to get the correct version of JSR-166y.jar is described on the project home page (the Parallelizer section) or if using Maven, try the wiki page –
    The issue with ActorMessage is a known and now fixed problem related to groovyc in 1.6.4, which was used to generate gparallelizer’s jar.
    Taking sources from the gpars project trunk might not give you the best experience, it really depends on when you touch it.
    The project is now undergoing quite turbulent times so I recommend to be a bit more patient and wait for the next gpars (beta) release. It won’t take long.
    Feel free to submit your comments or issues you find to the gpars mailing list. We’re very quick in responding.


  2. Dierk said

    Hi, thanks for trying gpars and reporting about it.

    If you have any issues installing or running it, please don’t hesitate to post to the gpars user mailing list or leave a comment on the wiki. This will help us to iron out any rough edges and will help other users as well.

    Thanks a lot

    Thank you Dierk for the reply. I have applied for approval on the mailing list… hope I got the correct mailing list. 🙂

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