Re: [boost] Boost Asio on multi processor environment

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2007-04-24 09:39:35

On Tue, 24 Apr 2007 17:59:29 +0530, Gaurav.Jain_at_[hidden] said:
> Hi,
> 
> I am designing a server which will going to run on multiprocessor and
> which will going to provide service to thousand of clients concurrently. 
> I am using boost asio library to do this. I want to know how can I use
> one io_service object per CPU approach for this?

I'm sure I've outlined this in another email somewhere, but I can't find
it right now. Anyway, the basic idea is as follows:

- Create an io_service for each CPU.

- Create an io_service::work object for each io_service to keep it
running when it would otherwise have nothing else to do.

- Spawn a thread for each io_service to call io_service::run().

- Create a tcp::acceptor on one of the io_services.

- Create your tcp::socket objects on any of the io_services, using some
sort of load balancing scheme to choose the io_service to use (e.g.
round robin).

- Ensure that all communication between io_services uses message
passing, i.e. use io_service::post().

The core of the work would probably happen in a handle_accept
function(), e.g. using the Daytime.3 tutorial program as a starting
point:

  void start_accept()
  {
     // ------> Load balance here <------
    tcp_connection::pointer new_connection =
      tcp_connection::create(choose_io_service());

    acceptor_.async_accept(new_connection->socket(),
        boost::bind(&tcp_server::handle_accept, this, new_connection,
          asio::placeholders::error));
  }

  void handle_accept(tcp_connection::pointer new_connection,
      const asio::error_code& error)
  {
    if (!error)
    {
      // ------> Use message passing here <------
      new_connection->socket().io_service().post(
         boost::bind(&tcp_connection::start, new_connection));

      start_accept();
    }
  }

Cheers,
Chris