Re: Inbound connections limit in Windows XP

Simon Kissel wrote:
> In the non-Server editions of Windows, this queue, called "listen
> backlog" is fixed to 3 entries.

Ah! Thank you, that explains some strange stuff I've seen here with some
prototypes I've been working on.

We have a local network of 5 systems that need to monitor each other. One
of them is a spare that will automatically spring into active duty if any
of the four other systems shows symptoms of failure. For this purpose I
have conceived a "monitoring module" which is running on each system,
contacting the others through a quick TCP-level poll (round-robin style),
retrieving a short status message in each case. So each module also has a
single (multi-client) TCP server socket on which it accepts connections
from the others and returns status. I've noticed, however, that
occasionally a single connection attempt will fail. For each module there
are 4 potential clients, so I guess it is thinkable that they could be
"knocking on the door" all at the same time.

I wanted to do it this way here to have a low-latency picture on the
connectivity situation (instead of having to contend with the ever-fickle
disconnect detect situation, keepalive messages with timeouts, etc). Now
it appears I could be bumping my head against the "Listen backlog" limit
instead... sigh.

> Of course this is only an issue if you have big surges of new
> incoming connections. Spawning the client connection only takes a few
ms.

Are you sure? Theoretically a 'big surge' would only need to consist of
four clients, if they're a bit unlucky.
Thanks for your clarifications!

--
Kristofer


.

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