Re: [ojAlgo-user] optimizing from a .mps file

[David S. <d.s...@4c...>]

We have tried on problems with up to 2400 variables and 200 constraints/rows
and it solves it quickly (1.6~ seconds). Copied below is a complete case
which causes the problem described (for any .mps file I can give it):

import java.io.File;

import org.ojalgo.optimisation.OptimisationSolver;
import org.ojalgo.optimisation.OptimisationSolver.Result;
import org.ojalgo.optimisation.linear.mps.MathProgSysModel;


public class Temp2 {
	
	public static void main(String[] args)
	{
	
		File aFile = new File("temp.mps");

		MathProgSysModel mps = MathProgSysModel.makeFromFile(aFile);
	  
		OptimisationSolver os = mps.getDefaultSolver();
		Result rs = os.solve();
		
		System.out.println( rs.getSolution() );
	}
	
}

I am using v28 of ojAlgo, and running it through Eclipse 3.5. Stepping
through it I find that the thread is created at this point of BigDenseStore,
in the method fillMatching:

public void fillMatching(final MatrixStore<BigDecimal> aLeftArg, final
BinaryFunction<BigDecimal> aFunc, final MatrixStore<BigDecimal> aRightArg) {

        final BigDenseStore tmpLeftArg = this.cast(aLeftArg);
        final BigDenseStore tmpRightArg = this.cast(aRightArg);

        final int tmpLength = length;
        final int tmpHalf = tmpLength / 2;

        final Future<?> tmpFirstHalf = ConcurrentUtils.EXECUTOR.submit(new
Runnable() {

            public void run() {
                BigDenseStore.this.fill(0, tmpHalf, tmpLeftArg, aFunc,
tmpRightArg);
            }
        });
	
        this.fill(tmpHalf, tmpLength, tmpLeftArg, aFunc, tmpRightArg);

        try {
            tmpFirstHalf.get();
        } catch (final InterruptedException anException) {
            anException.printStackTrace();
        } catch (final ExecutionException anException) {
            anException.printStackTrace();
        }
    }

The Future object's thread never seems to stop running though I am not sure
why not.

Regards,
David


-----Original Message-----
From: Anders Peterson [mailto:an...@op...] 
Sent: 16 October 2009 22:05
To: oja...@li...
Cc: j.f...@4c...
Subject: Re: [ojAlgo-user] optimizing from a .mps file

On 16 okt 2009, at 14.25, David Stynes wrote:

> Hello,
> I am trying to use ojAlgo to read from a .mps file and use Linear/ 
> Mixed
> Integer Programming to solve it. Currently the code for this is as  
> follows:
>
> MathProgSysModel mps = MathProgSysModel.makeFromFile(aFile);
> OptimisationSolver os = mps.getDefaultSolver();
> Result rs = os.solve();
>
> This runs correctly and solves the .mps input file as desired.


Should have written somewhere that the MIP solver is new and  
experimental - glad to hear that it solves your problem. How big is it?


> However the
> second line (calling getDefaultSolver()) appears to start an  
> additional
> thread running or something, as the java process does not stop after  
> the
> rest of my code finishes (but the remaining code after this line  
> does get
> executed). Is this intended, and/or am I using it incorrectly and  
> how can I
> use it correctly to prevent the java process continuing to be active
> indefinitely instead of closing?


The MIP solver is multithreaded, but I don't see why any additional  
threads should be created before you call solve().

I have a number of junit tests that basically do what you do. As far  
as I can see they terminate as expected.

Could you step through the code and tell me more precisely where that  
thread is created?


/Anders


> Thanks,
> David
>
>
>
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