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

[Anders P. <an...@op...>]

On 19 okt 2009, at 12.18, David Stynes wrote:

> 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):


That sound s really good to me. How many of the variables are integer  
variables?


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


Should have realized this from the beginning. ojAlgo keeps a  
ThreadPoolExecutor instance with a non-zero core pool size. This is  
used all the time by ojAlgo for all sorts of things. You have to  
"quit" your program.

http://ojalgo.org/generated/org/ojalgo/concurrent/ConcurrentUtils.html#EXECUTOR

/Anders


> -----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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