Le 11 août 2010 à 08:27, hvlad a écrit :

>> when playing in the > 300 attachments range (could be 350 or 400, does not seem precise), I have seen new attachments denied (-904, code 335544375) and this logged in firebird log:
>>
>> XNET error: Server failed to respond on connect request
>>
>> What kind of limitation could this be?
>
> Listener process was not in time when launched worker process to handle new connection.
> This is possible when there is a lot of simultaneous requests for a new connections.
> fbclient waits for (10 sec, iirc) response from a server on initial packet and if wait was timed out message above is logged at firebird.conf.
>
> It was improved recently, see
> http://tracker.firebirdsql.org/browse/CORE-2769

Thanks a lot Vlad. I have read about CORE-2769 and will move up to latest 2.1 build when possible, just in case.

Though, I fear what I experienced might have been different. There was no load nor timeouts involved. All new attachments were denied "instantly" (within a second for what I have seen, and probably less), not some attachments, all attachments from that point on.

Either the total number of attachments hit a limit, internally (Firebird itself) or externally (some OS limitation), or some internal state went wrong. To fix I did shutdown all client processes, restarted the inet service, and then let the application processes start again, and all was OK again. Just reducing the number of existing connections was not enough. When it started failing accepting connections, it failed until full stop (but existing connections were OK and working.)

Maybe XNET is limited by some Windows OS own limitation? Pipes? Sync handles?
Maybe I should turn to tcp over localhost but I don't like eating tcp sockets by pair just for these local connections.

Ok, I'll try to gather better and more complete picture of this when it will happen again, might take days or weeks, because I have seen this only 3 times over the last 3 months.

Thanks again,
Sincerely,

—
Olivier Mascia