Re: [Boost-users] [boost::asio::serial_port] Calling cancel() causes Run-Time Check Failure #0 on Visual Studio 2010 SP1

Subject: Re: [Boost-users] [boost::asio::serial_port] Calling cancel() causes Run-Time Check Failure #0 on Visual Studio 2010 SP1
From: Dario Ramos (dario_ramos_at_[hidden])
Date: 2012-03-15 11:04:28

Igor said:

> I couldn't reproduce this crash (Boost 1.49, MSVC10, Win7), maybe
> because I don't have any trafic on COM1, but any way -- asio objects
> are not thread-safe, so it might be unsafe to call cancel() this way.
> Instead, try using the following: ioService.post([&]
> {serialPort.cancel();}); - and see if it helps.
> <http://lists.boost.org/mailman/listinfo.cgi/boost-users>

It definitely helps; it crashed 0 out of 10 times, which is enough for me
(it crashed every time before, even without traffic). I didn't know asio
objects weren't thread-safe.
I need to use them in a multithreaded environment; I have a reader and a
writer thread. I suppose that wrapping every call to the serial_port object
inside a post message would avoid any trouble but might be too slow. Am I
right? Are there some general guidelines I should follow when using asio
objects in multithreaded environments?

Richard said:

> Are you using Windows XP? If you are it is due to Win32 API CancelIo can
> only cancel IO requests from the same thread as the CancelIO request
> itself. Vista and later has CancelIoEx which can cancel IO requests from
> any thread. As I remember Boost Asio Serial checks whether CancelIoEx is
> supported and if not will throw an exception if it determines the CancelIo
> request is not on the same thread as the outstanding IO request.
>

That makes a lot of sense, since I am indeed using XP. It also explains why
using post solves the issue. Anyway, if Boost performs that check, the
Runtime Check failure shouldn't happen. Could this be a bug?

-- 
*Darío Eduardo Ramos*
Meditech S.A. www.meditech.com.ar
([phone], Interno 31
Av. Julio A. Roca 3456
Florida Oeste, Bs.As. Argentina