boost::fibers::use_scheduling_algorithm< boost::fibers::asio::round_robin >( io_ptr);
boost::fibers::fiber([io_ptr](){
for ( int i = 0; i < 10; ++i) {
boost::fibers::use_scheduling_algorithm< boost::fibers::asio::round_robin >( io_ptr);
boost::fibers::fiber([io_ptr](){
for ( int i = 0; i < 10; ++i) {