My problem is with the function that is to be executed last: how can I wait for that to be executed before stopping the io_service and joining the thread?
Usually you don't have to stop io_service explicitly - when it runs out of work, it stops by its own. So if all you need is to perform several functions/functors on io_service thread - just post them to io_service, and join io_service thread(s): // pseudo-code! { asio::io_service io; io_.post(functor1); io_.post(functor2); thread t(&io_service::run, &io); t.join(); // when io_service runs out of jobs, run() exits. } If you need to get more control over io_service::run "lifetime", you can use work object, like in your example: // pseudo-code! { asio::io_service io; shared_ptr<io_service::work> work(new io_service::work(ios)); thread t(&io_service::run, &io); io_.post(functor1); io_.post(functor2); // do something... // when there's not more real work, and all the copies of "work" shared ptr are reset, io_service::run will exit t.join(); } If you still need to get synchronized with one of your functors being executed in another thread, use boost::condition_variable (the functor sets condition, main thread waits for condition): http://www.boost.org/doc/libs/1_41_0/doc/html/thread/synchronization.html#th...