RE: [ros-dev] Loopback problem

[Ge van Geldorp]

>   From: Phillip Susi
>  
>  Ge van Geldorp wrote:
> >   I've been wrong before, but that's my
> > interpretation of 
> >  what's happening. We've only sent one byte and are trying
> >  to send another single byte. 
>  
>  Wait a second... why is it sending only one byte at a time?  
>  The caller is only send()ing one byte at a time? 
Yup.

>   The caller really should not be doing that. 
Hmm, I just read a Larry Wall quote: "we're not terribly interested in
telling people what they can't do" :-)

>   You may be seeing the nagle 
>  algorithm kicking in then, which specifically tries to wait 
>  for an ack before sending more frames, _unless_ there is 
>  enough queued data to send another complete frame. 
>  This prevents tons of single byte frames from flooding the 
>  network, instead coalescing them into larger frames.
>  
>  I'm curious now about the application.  Why is it sending one 
>  byte at a time to itself via the loopback?  That seems to be broken. 
The application is the Mozilla ActiveX control. My guess (but I haven't
studied its source code to confirm this) is that it is doing this as a form
of inter-thread communication. It might be broken, but it works ok on
Windows, so we have to make it work also.
In my first post I've included a simple test app which demonstrates the
behaviour. I can send it again if you like.

GvG