[asio-users] Re: asio-users digest, Vol 1 #35 - 2 msgs

[godot <mo...@gm...>]

asi...@li... schrieb:
> I suspect that the problem is due to the timeout granularity on the
> Windows implementation of select(). It appears that a very short
> timeout (<10 milliseconds?) makes select() return immediately. If the
> current time is very close to the timer expiry, this immediate return
> might cause the select reactor to spin (thus accounting for the CPU
> usage you observe) until the timer expiry is reached.
>
> Can you please try the following change to see if it makes a
> difference:
>
> RCS file: /cvsroot/asio/asio/include/asio/detail/socket_ops.hpp,v
> retrieving revision 1.36
> diff -u -r1.36 socket_ops.hpp
> --- include/asio/detail/socket_ops.hpp  23 Feb 2006 12:31:08 -0000     
> 1.36
> +++ include/asio/detail/socket_ops.hpp  27 Feb 2006 11:38:06 -0000
> @@ -466,6 +466,9 @@
>      ::Sleep(milliseconds);
>      return 0;
>    }
> +  if (timeout && timeout->tv_sec == 0
> +      && timeout->tv_usec > 0 && timeout->tv_usec < 10000)
> +    timeout->tv_usec = 10000;
>  #endif // defined(BOOST_WINDOWS)
>    return error_wrapper(::select(nfds, readfds, writefds, exceptfds,
> timeout));
>  }
>   
Hi Chris,
I changed the socket_ops.hpp and recompiled but it makes no difference.
While stepping through your select function I noticed: on first call
"timeout" is set to 1 second, on all following calls the "timeout"
pointer is 0.
So,
1. your code change does not apply and
2. ::select will return immediatly indeed, as you suspected

Maybe this might help,
Regards,
Boris

PS: Thanks for your great work, I'm using asio extensivly in gui apps
and I hope asio will be accepted to boost.