A general solution is to use an empty task as a dummy parent. See http://software.intel.com/en-us/blogs/2008/07/02/implementing-task_group-interface-in-tbb for code that implements a general task group interface using this approach. It's on our to-do list to add something like this to TBB and add a general template for running a fixed number of functors concurrently.
For exposition, below is a simple example that runs two tasks concurrently.
#include "tbb/task_scheduler_init.h"
#include "tbb/task.h"
#include
void DummyLoad() {
for( volatile int x=0; x!=100000000; ++x )
continue;
}
class X: public tbb::task {
tbb::task* execute() {
std::printf("X is runningn");
DummyLoad();
std::printf("X finished runningn");
return NULL;
}
};
class Y: public tbb::task {
tbb::task* execute() {
std::printf("Y is runningn");
DummyLoad();
std::printf("Y finished runningn");
return NULL;
}
};
int main() {
tbb::task_scheduler_init init;
tbb::empty_task* e = new( tbb::task::allocate_root() ) tbb::empty_task;
// 3 = 1 for each child plus 1 for the wait
e->set_ref_count(3);
X* x = new( e->allocate_child() ) X;
Y* y = new( e->allocate_child() ) Y;
e->spawn(*x);
e->spawn(*y);
// Wait for childen to finish
e->wait_for_all();
e->destroy(*e);
return 0;
}
