boost::asio::io_service::run() is not exiting when i call boost::asio::io_serive::stop() - sockets

Question

Hi I having written one simple application which uses the asynchronous socket functions. I am facing some problems while closing the socket.
I am using 5 second timer before calling the async_connect on the socket. In some cases the connection is not happening and timer expires. When timer is expired I am closing the socket tcp_socket.close(). But the thing is my connection callback handler is not at all called with the boost::asio::error::operation_aborted error when i tried to cancel instead of close. The same thing is happening for the next all the async connection invokes.
Eventhough I am closing the tcp socket and destroying the client_session object join() call on the created thread is not coming out means io_service::run() is still running not exiting...:-( I don't know why this is happening... tried lot of other ways still facing the same problem.
I am not getting what is the problem, all suggestions and solutions will be appreciated.
My real code some what look like this.
class client_session
{
public:
client_session(boost::asio::io_service& io_service_ )tcp_socekt_(io_service_),
timer_(io_service_)
{
}
~client_session()
{
tcp_socket_.close();
}
void OnTimerExpired(const boost::system::error_code& err)
{
if( err ) tcp_socket_.close();
}
//Its just for example this will be called from upper layer of my module. giving some information about the server.
void connect()
{
//Here am starting the timer
timer_.expires_from_now(boost::posix_time::seconds(2));
timer_.async_wait(boost::bind(&OutgoingSession::OnTimerExpiry, this,PLACEHLDRS::error));
.......
tcp_socket_.async_connect(iterator->endpoint(), boost::bind( &OutgoingSession::handle_connect, this, _1, iterator));
......
}
void OnConnect(const boost::system::error_code& err)
{
//Cancelling the timer
timer_.cancel();
.....
//Register for write to send the request to server
......
}
private:
tcp::socket tcp_socket_;
deadline_timer timer_;
}
void main()
{
boost::asio::io_service tcp_io_service;
boost::asio::io_service::work tcp_work(tcp_io_service);
boost::thread* worker = new boost::thread(&boost::asio::io_service::run,&tcp_io_service);
client_session* csession = new client_session(tcp_io_service);
csession->connect();
sleep(10);
tcp_io_service.stop();
delete csession;
worker.join(); //Here it not coming out of join because io_service::run() is not exited yet.
cout<<"Termination successfull"<<endl;
}

Answer 1

There seem to be a couple of different things wrong with the posted code. I would suggest starting with smaller steps i.e. along the lines of
start and stop asio worker thread cleanly ( see explanation below )
add code to start timer: handle OnTimerExpired correctly, check error code
add in code for async_connect: when connect handler is called, cancel timer and check error code.
add in other asynchronous operations, etc.
For one, when you cancel the timer in the connect handler, the OnTimerExpired handler will be invoked with boost::asio::operation_aborted and then you close the socket, which is probably not what you want to do.
Further, you give the io_service work, yet still call stop. Generally if you give the io_service work, you want to stop the execution thread by removing the work (e.g. This can be accomplished by means of storing work in a smart pointer and resetting it) and letting the currently started asynchronous operations finish cleanly.