[GRASS5] network traffic

[Glynn Clements]

Roger Miller wrote:

> I run GRASS (5.0.0pre2) through ssh on a ppp connection to my installation at 
> the office.  I used the command line interface.  When I start a monitor the 
> lag between keystrokes and displayed results often increases.  Starting a 
> second monitor virtually stops everything.  The lag between the time a key is 
> pressed and the time it appears on the screen sometimes exceeds 30 seconds.
> 
> I started pppstat on my local machine to see what was going on, and found 
> that the first monitor generated a continuous stream of network traffic at 
> about 8kb/second incoming and 4-5 kb/s outgoing.  Somewhat bizzarly, starting 
> a second monitor dropped that stream to about 5 kb/second incoming and about 
> 200 bytes/s outgoing.  The command shell slowed to a near halt.
> 
> After I stopped the second monitor the network traffic initially stayed at 
> about 4 kb/s incoming and 200 bytes/s outgoing, but the traffic later rose 
> fairly gradually back to about 8 kb/s incoming and 4-5 kb/s outgoing.
> 
> All of this behavior is with a blank monitor--nothing at all in the display.  
> The behavior is the same regardless of whether the monitor is raised or not.

I think I know what's going on. XDRIVER is continuously polling the X
display connection and the GRASS monitor socket alternately. It should
really be doing a select() on both descriptors.

I'll look into a fix; in the meantime, you may be able to reduce the
traffic by increasing the timeout in get_connection_sock() in
display/devices/lib/connect_sock.c.

-- 
Glynn Clements <glynn.clements at virgin.net>