Mateusz Loskot :: hacking on, working out, living up

parallel_sort problem fixed

21 Feb 2010 | mloskot

My problem with crashing programs using TBB has been solved. Alexey Kukanov replied to my question explaining that because I use TBB 2.1, thus I have to explicitly initialise the task scheduler. Without this initialization, no context (root) for tasks is created, so no tasks possible.

Simply, I was reading latest manual which was generated for TBB 2.2 (available in Ubuntu 10.04), so I missed this legacy requirement. In TBB 2.2 and later, the initialization is optional:

Using task_scheduler_init is optional in Intel? TBB 2.2. By default, Intel? TBB 2.2 automatically creates a task scheduler the first time that a thread uses task scheduling services and destroys it when the last such thread exits.

Correct version of the example program should look as follows:

#include <tbb/task_scheduler_init.h>
#include <tbb/parallel_sort.h>
#include <cmath>
#include <vector>
using namespace tbb;
int main()
    task_scheduler_init tbb_init; // automatic

    const int n = 100000;
    std::vector<double> a(n);
    for (int i = 0; i< n; i++)
        a[i] = std::sin(double(i));
    parallel_sort(a.begin(), a.end());
Fork me on GitHub