std::async should work with 4.7.1, but it doesn't?

Question

I can not compile

template 
int parallel_sum(const RAIter beg, const RAIter end) {
 const auto len = end-beg;
 if(len < 1000) return std::accumulate(beg, end, 0);

 const RAIter mid = beg + len/2;
 auto handle = std::async(std::launch::async, parallel_sum, mid, end);
 const int sum = parallel_sum(beg, mid);
 return sum + handle.get();
}

int main() {
 std::vector v(10000, 1);
 std::cout 

using "g++ -Wall -std=c++11", but running it I get terminate called after throwing an instance of 'std::system_error' what(): Unknown error -1
Aborted (core dumped)

Answer 1

You need to compile and link using -pthread to make use of multithreading.