Simple way to execute two parallel tasks in TBB

Question

I need to execute two parallel tasks using Intel Threading Building Blocks, and wait till both are finished.

I can do it as follows:

        tbb::parallel_for( tbb::blocked_range<int>( 0, 2, 1 ), [&] ( const tbb::blocked_range<int>& range )
        {
            for ( int i = range.begin(); i < range.end(); ++i )
            {
                if ( i == 0 )
                    task0();
                else if ( i == 1 )
                    task1();
            }
        } );

But I guess that tbb::parallel_for is not the best solution for this; is there a better/simpler method to achieve the same in TBB?

Answer 1

For a small number of tasks, you can use tbb::task_group:

tbb::task_group g;

g.run([&] { task0(); });
g.run([&] { task1(); });

// do other work while tasks run ...

g.wait(); // wait for all tasks to finish

As a small optimization, can run one of the tasks in the current thread:

tbb::task_group g;

g.run([&] { task1(); }); // spawn a parallel task

task0(); // run one task in current thread

g.wait(); // wait for parallel task(s) to finish