Subject: Futex using boost, threads never wakeup Hello all I posted the following question in stackoverflow https://stackoverflow.com/questions/75538799/futex-using-boost-threads-never... 0 <https://stackoverflow.com/posts/75538799/timeline> I am studying about futex synchronisation Following up the manual <https://man7.org/linux/man-pages/man2/futex.2.html> , I tried to syncroniaze threads using boost futex However the threads never wake up #include <iostream>#include <atomic>#include <boost/fiber/detail/futex.hpp>#include <thread>#include <vector>#include <chrono>void wait(std::atomic<int> & futexp){ int one = 1; while(std::atomic_compare_exchange_strong(&futexp, &one, 0)) {} std::cout << std::this_thread::get_id() << "," << futexp.load() << std::endl; boost::fibers::detail::futex_wait(&futexp,0); // std::this_thread::sleep_for(std::chrono::milliseconds(5000)); }void fpost(std::atomic<int> & futexp){ int zero = 0; if (std::atomic_compare_exchange_strong(&futexp, &zero, 1)) { boost::fibers::detail::futex_wake(&futexp); } } std::atomic<int> futexp{1};int main() { std::vector<std::thread> vec; for(int i =0 ; i< 5;++i) { vec.emplace_back([]() { wait(futexp); fpost(futexp); }); } Code demo <https://godbolt.org/z/94hMsrW4a> I am using boost 1.66 and gcc 9.1 What goes wrong with this piece of code ?