VC++ PPL, assigning a Scheduler to a task_group

Question

Pretend we have a class:

class Foo
{
private:
 Concurrency::task_group _tasks;  
};

How do I assign a scheduler to this task_group? I do not want to use the default scheduler as I also use parallel_for elsewhere in the code.

The task_group will have it's level of maxconcurrency set through the scheduler to use either all cores, or a subset of them depending on the hour. The application may run for hours, so the maxconcurrency will be required to change.

I cannot find a nice way of doing this in PPL. In .NET this is very easy - all you have to do is set MaxDegreeOfParallelism.

Any ideas?

Answer 1

There are several solutions:

1. If you use the MSVS C++ 2012 than:

   _tasks.run([]()
   {
       Context::Oversubscribe(true);
       //
       // long time running task
       //
      Context::Oversubscribe(false);
   });
   

2. If you APP works on Win7x64 or Windows Server 2008 R2 than try UMS:

   Scheduler::SetDefaultSchedulerPolicy( SchedulerPolicy(1, SchedulerKind, UmsThreadDefault) );
   

3. And last. Create new curren sheduler with new oversubscribe policy (enlarge MaxConcurrency) befor create new heavy time task.

   CurrentScheduler::Create( SchedulerPolicy(1, MaxConcurrency, 8) );
   _tasks.run([](){
       //
       // long time running task
       //
    });
   CurrentScheduler::Detach();