I have a program that calls Eigen from a std::thread (Eigen is set to single-threaded using Eigen::setNbThreads(1)).

I never had any problem with that setup, on any platform, until now.

I just upgraded to El Capitan, and it looks like my program now crashes inside Eigen, when it calls omp_get_num_threads().

I am able to reproduce it without Eigen, so it's not Eigen's problem. But I'm just wondering if it's possible to make Eigen not call any OpenMP function if set to use 1 thread?

Thanks!

Test program:

Code: Select all

#include <omp.h>

#include <iostream>
#include <thread>

void thread_main()
{
        std::cout << omp_get_num_threads() << std::endl;
}

int main()
{
        std::thread t(thread_main);

        t.join();
}


Looks like that's fixed in GCC 5.2, and calling omp_get_num_threads() from a std::thread is working again.

Would still be nice to have a special case for if num threads is set to 1, though, in case another implementation does this again (interaction between OpenMP and other threading libraries is undefined).

Good idea, done in the devel branch, changeset https://bitbucket.org/eigen/eigen/commits/b8d476bed76b

Thanks!