Igor, Passthru APP test hangs   

Hello Igor,

This site http://www.nrj.fr/music causes the Passthru APP test
application (from your sample) to hang. Any ideas why.

Using VC++ 2005 (sp1), WinXP sp3 , and IE 7.

Regards,

MH

date: Tue, 1 Jul 2008 06:39:20 -0700 (PDT)   author:   mh

Re: Igor, Passthru APP test hangs   

mh  wrote:
> This site http://www.nrj.fr/music causes the Passthru APP test
> application (from your sample) to hang. Any ideas why.

Something on that page seems to be making a synchronous HTTP request 
(probably a script using XMLHttpRequest object). This then deadlocks 
with the APP calling CMainDlg::Log from worker thread. Log() involves a 
few SendMessage calls to the window running on the main thread, which 
block until that thread processes messages, which in turn blocks until 
the APP finishes the request. Just putting "return;" as the first line 
of CMainDlg::Log prevents the problem (but you don't get any diagnostic 
output anymore, of course).

A smarter strategy would be to post a user-defined message to the main 
window (with a heap-allocated string in LPARAM or something) and have 
the window put it into the box once the message arrives on the main 
thread. Or some other form of producer/consumer queue between the 
workers and the main thread.
-- 
With best wishes,
    Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not 
necessarily a good idea. It is hard to be sure where they are going to 
land, and it could be dangerous sitting under them as they fly 
overhead. -- RFC 1925

date: Tue, 1 Jul 2008 12:41:13 -0400   author:   Igor Tandetnik

Re: Igor, Passthru APP test hangs   

Thank you.

Regards,

MH

On Jul 1, 8:41 am, "Igor Tandetnik"  wrote:
> mh  wrote:
> > This sitehttp://www.nrj.fr/musiccauses the Passthru APP test
> > application (from your sample) to hang. Any ideas why.
>
> Something on that page seems to be making a synchronous HTTP request
> (probably a script using XMLHttpRequest object). This then deadlocks
> with the APP calling CMainDlg::Log from worker thread. Log() involves a
> few SendMessage calls to the window running on the main thread, which
> block until that thread processes messages, which in turn blocks until
> the APP finishes the request. Just putting "return;" as the first line
> of CMainDlg::Log prevents the problem (but you don't get any diagnostic
> output anymore, of course).
>
> A smarter strategy would be to post a user-defined message to the main
> window (with a heap-allocated string in LPARAM or something) and have
> the window put it into the box once the message arrives on the main
> thread. Or some other form of producer/consumer queue between the
> workers and the main thread.
> --
> With best wishes,
>     Igor Tandetnik
>
> With sufficient thrust, pigs fly just fine. However, this is not
> necessarily a good idea. It is hard to be sure where they are going to
> land, and it could be dangerous sitting under them as they fly
> overhead. -- RFC 1925

date: Wed, 2 Jul 2008 03:13:32 -0700 (PDT)   author:   mh