// create another actor that calls 'hello_world(mirror_actor)';
system.spawn(hello_world,mirror_actor);
// system will wait until both actors are destroyed before leaving main
// for i in {0..5}; do echo -n "impl:$i "; runtime ./hello_world --impl=$i --num=2000000; done
// for i in {0..5}; do echo -n "impl:$i "; runtime ./hello_world --caf#scheduler.policy='sharing' --caf#scheduler.max-threads=1 --impl=$i --num=2000000; done