[sldev] UDP to TCP/HTTP - performance issues?

[Tateru Nino]

Kelly Linden wrote:
> Callum Lerwick wrote:
>> On Wed, 2007-11-14 at 23:57 +1100, Tateru Nino wrote:
>>   
>>> I'm noting a suspicious stall in the viewer when a presence popup
>>> happens. Disabling the popup does not seem to change the behaviour.
>>> Getting a friend to log in and log out, the viewer still stalls for a
>>> second or so around the time the popup _would_ have appeared if it were
>>> enabled. That's another data point for you.
>>>     
>>
>> I've noticed this too. My wife has even complained about it. At one
>> point it would even crash, though that seems to have been fixed.
>>
>> I've also noticed that during periods of high (total?) packet loss, the
>> viewer will completely freeze. Which happens often when you're on a less
>> than stellar wireless connection. No screen refreshes, CPU usage drops
>> to zero. Why is network IO capable of blocking the graphics engine? The
>> rest of the machine remains responsive, so I don't think its an
>> X11/OpenGL problem.
>>   
> Even if you choose not to show the alerts the same data is sent to
> your viewer.  When you log in that is a list of all your friends that
> are online, when a friend logs in or out it is a single message with
> the ID and online status.  This should be a really small packet of
> info, and I think it is still UDP.  If there is a stall here I bet it
> has something to do with however we are storing friends in memory -
> some bug that makes inserting into that list really slow on large
> lists perhaps?  I have not recently looked at this code so am guessing
> here, but that is the first place I would look.
It's also writing to the chatlog file, if you have logging enabled - but
the stall doesn't appear when you're actually... chatting. It does
suggest that maybe there's issues or delays with looking up the UUID of
an agent who is not present in the vicinity.

-- 
Tateru Nino
http://dwellonit.blogspot.com/