My question is relevant to Boost Asio in the sense that I was wondering as to whether there are any specific reasons not to make the io_service object in particular, global. If this is not the case, which is to say no special reasons not to make io_service in particular global, then you are right; it is a design question and I then have nothing further to enquire about. Kind regards, Philip Bennefall ----- Original Message ----- From: "Jinqiang Zhang" <jasonzha@gmail.com> To: <boost@lists.boost.org> Sent: Wednesday, July 20, 2011 5:00 AM Subject: Re: [boost] Boost Asio io_service as global? your question is not relevant to boost::asio. You question is a design question: Should a frequent-accessed variable being global? My taste to your question is: I don't like global variable, so I would like to pass the reference around. jinqiang