[Cbc] CbcEventHandler in multithreading

[Alexis]

Hi,

With the help of Tobias, I managed to compile CBC standalone in VS2015. 
Inspection of the CPU usage on my machine indicates that multithreading 
seems to work.

I have a few more questions:

1 - Does the parameter with -threads indicates the number of extra 
threads? 0 would mean that there is only the master thread, essentially 
no multithreading?

2 - I am not sure I understand at this point the parameter threadMode_, 
but I am going to look more into it.

3 - More importantly, I am trying to use multithreading with my 
application. Compilation is ok. I am mostly wondering about the behavior 
of the handlers in the multithreading settings.

My code is essentially an extended version of driver6.cpp/driver4.cpp so 
I used to have

   // Pass to Cbc initialize defaults
   CbcModel modelA(solver1);
   CbcModel * model = &modelA;
   CbcMain0(modelA);
   // Event handler
   MyEventHandler3 eventHandler;
   model->passInEventHandler(&eventHandler);
   /* Now go into code for standalone solver
      Could copy arguments and add -quit at end to be safe
      but this will do
   */
     const char * argv2[]={"driver4","-solve","-quit"};
     CbcMain1(3,argv2,modelA);

Now, I have

*    const char * argv2[]={"driver4","-threads, "X", "-solve","-quit"};*
*    CbcMain1(5,argv2,modelA);*

- Is eventHandler shared between all the threads? Or is there one 
handler (copy) per thread?
- In the first case, is eventHandler thread safe?
- What would be the best way to get the best solution in the tree? 
Currently, I just have to call

CbcEventHandler::CbcAction
MyEventHandler3::event(CbcEvent whichEvent)
{
   // If in sub tree carry on
   if (!model_->parentModel()) {
     if (whichEvent==solution||whichEvent==heuristicSolution) {
       printf("value of solution is %g\n",model_->getObjValue());
   } else {
       return noAction; // carry on
   }
}

Thanks!

Alexis

-- 
Alexis Guigue, E.I.T., B.Eng., M.A.Sc., Ph.D.
Software Engineer/Research Engineer
604-519-6222, ext. 107

Softree Technical Systems Inc. <http://www.softree.com>
Engineering an Easier Way

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