Jim LaGrone <jlagr...@cs.uh.edu> wrote on 08/27/2009 09:38:38 PM:
> Eventually I'll get the hang of this. Thanks for all your help.
>
>
> On Aug 27, 2009, at 6:13 PM, Igor Peshansky wrote:
>
> > Jim LaGrone <jlagr...@cs.uh.edu> wrote on 08/27/2009 06:43:57 PM:
> >
> >>
> >> On Aug 27, 2009, at 3:55 PM, Igor Peshansky wrote:
> >>
> >>> You can also use the place-local idiom, as follows:
> >>>
> >>> val norms = Array.make[Double](Dist.makeUnique(), (Point)=>0.0);
> >>> finish ateach ( (p) in distS.places() ) {
> >>> for ( (i, j) in distS | p ) { // at this point, p == here
> >>> norms(p.id) += Math.sqrt(S(i,j).real*S(i,j).real +
> >>> S(i,j).image*S(i,j).image);
> >>> }
> >>> }
> >>> rawNormPower2 = norms.sum(); // a distributed reduction
> >>>
> >>> Here, norms is an array with a unique distribution (which has one
> >>> point
> >>> per place). The ateach loop again spawns parallel iterations on
> >>> each
> >>> place (but now there's one per place covered by the distribution).
> >>> The
> >>> body of the ateach has a sequential loop that runs over the part of
> >>> distS
> >>> that lives in that place. Each iteration of that sequential loop
> >>> updates
> >>> the local element of norms. There is no need for atomic, since all
> >>> updates happen sequentially. Once the ateach loop is done, a
> >>> (distributed)
> >>> reduction is performed over the norms array, and the sum is stored
> >>> in the
> >>> final result location.
> >>
> >>
> >> Using this method and Java backend, I have
> >>
> >> rawNormPower2 = 0;
> >> val norms = Array.make[Double](Dist.makeUnique(), (Point)=>0.0);
> >> finish ateach( (p) in distS.places() ){ //line 327
> >> for( (i,j) in distS | p ){
> >> norms(p.id) += Math.sqrt(S(i1,j1).real*S(i1,j1).real +
> >> S(i1,j1).image*S(i1,j1).image);
> >> }
> >> }
> >> rawNormPower2 = norms.sum()/( N*Mc ); //line 333
> >>
> >>
> >> but get this
> >>
> >> /Users/jlagrone/GradSchool/Research/workspace/X10-code/SSCA3-X10/src-
> >> par/State.x10:327: Could not infer type for formal parameter.
> >> /Users/jlagrone/GradSchool/Research/workspace/X10-code/SSCA3-X10/src-
> >> par/State.x10:327: Could not infer type for formal parameter.
> >> /Users/jlagrone/GradSchool/Research/workspace/X10-code/SSCA3-X10/src-
> >> par/State.x10:333: No valid method call found for sum() in
> >> x10.lang.Array[x10.lang.Double].
> >
> > Sorry, this will teach me to actually test the code before sending
> > it out.
> > Line 327 should be "finish for ( p in distS.places() ) async (p) {".
> > In line 33, replace "sum()" by "reduce((a:Int,b:Int)=>a+b, 0)".
> >
>
> First -
>
> reduce((a:Int,b:Int)=>a+b, 0) doesn't compile.
D'oh. "reduce((a:Double,b:Double)=>a+b, 0.0)", of course -- you're
dealing with doubles, not ints.
> The API looks like this should work:
>
> reduce(Double.+,0)
>
> It compiles but I don't know about the correctness.
That should definitely work in SVN HEAD -- I wasn't sure it would in
the 1.7.* releases, so I didn't mention it.
> Second -
>
> Using this code:
>
> val norms = Array.make[Double](Dist.makeUnique(), (Point)=>0.0);
> finish for ( p in distS.places() ) async(p){
> for( (i,j) in distS | p ){
> norms(p.id) += Math.sqrt(S(i,j).real*S(i,j).real +
> S(i,j).image*S(i,j).image);
> }
> }
>
> I get this output for places 3, 2, & 1:
>
> BAD PLACE EXCEPTION
> BAD PLACE EXCEPTION
> BAD PLACE EXCEPTION
> x10.lang.BadPlaceException: object=State Object {/*object values
> omitted*/} access at place=(Place 3)
> at x10.runtime.Runtime.placeCheck(Runtime.java:699)
> at State$2.apply(State.java:674)
> at x10.runtime.Activity.now(Activity.java:222)
> at x10.runtime.Activity.run(Activity.java:156)
> at x10.runtime.Worker$3.apply(Worker.java:330)
> at x10.runtime.impl.java.Runtime.runAt(Runtime.java:96)
> at x10.runtime.Worker.loop(Worker.java:317)
> at x10.runtime.Worker.join(Worker.java:246)
> at x10.runtime.Pool$5.apply(Pool.java:418)
> at x10.runtime.impl.java.Runtime.runAt(Runtime.java:96)
> at x10.runtime.Pool.join(Pool.java:410)
> at x10.runtime.FinishState.waitForFinish(FinishState.java:83)
> at x10.runtime.Runtime.stopFinish(Runtime.java:1068)
> at State.formImage(State.java:731)
> at State.stage1(State.java:1417)
> at RUN_knowledgeFormation.main(RUN_knowledgeFormation.java:466)
> at
RUN_knowledgeFormation$Main$1.apply(RUN_knowledgeFormation.java:48)
> at x10.runtime.Activity.now(Activity.java:222)
> at x10.runtime.Activity.run(Activity.java:127)
> at x10.runtime.Worker$3.apply(Worker.java:330)
> at x10.runtime.impl.java.Runtime.runAt(Runtime.java:96)
> at x10.runtime.Worker.loop(Worker.java:317)
> at x10.runtime.Runtime.start(Runtime.java:143)
> at RUN_knowledgeFormation$Main.main(RUN_knowledgeFormation.java:35)
> at x10.runtime.impl.java.Runtime.run(Runtime.java:46)
> at java.lang.Thread.run(Thread.java:613)
>
>
>
> A query on Place.MAX_PLACES returns 4 and I'm using a dual-core with
> Java backend.
>
> Any suggestions?
Interesting. The above code should work, unless S is a field of an
object that lives in place 0 (e.g., if S is really this.S). If that
is the case, simply store S in a local variable (e.g.,
"val S = this.S") and let the async capture it. Otherwise, I'd
suspect a bug in the Java backend implementation...
Igor
--
Igor Peshansky (note the spelling change!)
IBM T.J. Watson Research Center
XJ: No More Pain for XML's Gain (http://www.research.ibm.com/xj/)
X10: Parallel Productivity and Performance (http://x10.sf.net/)
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