I would sniff the packets to and from the server and NIC of the offending
application and see if there is anything going on. Also I would sniff the
packets from the other clients to the server and see how far the connect
gets.

Could be client hogging the connection to the server, strange that another
server can still connect though.

JAC

""Wilson, Fred"" <fred.wilson@...> wrote in message
news:E9E4431A916AD21191FD00104B986AEFC23988@......

> We've had an interesting problem at a site, and since, have been able to
> reproduce it here in the lab. We have some software running on multiple
> clients (NT4.0SP5) talking to an IB (5.6) database running on a server
> (NT4.0SP5, TCP/IP NP))..
> The software is running on 7 clients or so.
> We have other software (also talking to the same DB) running on another
> client, configured the same.
> At some point, we believe that the offending software is trashing

(through

> poor threading design) one of the datamods. What we see is a "lockup" of

all

> the clients. That is, the software freezes, unable to "talk" to the
> database. This even includes the other, somewhat non-related software,
> running on another client.
> Attempting to connect to the database, from a client machine, via WISQL,

at

> this time, produces a "hung" WISQL application. That is it simply hangs

with

> the SQL shaped cursor.
> From any of the clients, when in this state, you can open a command prompt
> and you *can* successfully ping the server box.
> IB does *not* appear to be dead. The CPU usage (IB) drops to 0% on the
> server.
> Opening WISQL on the server and attempting to connect via a local

connection

> *IS* successful and the database appears fine.
> Opening WISQL on the server and attempting to connect via TCP/IP is *NOT*
> successful, it simply "hangs", as with the clients, with a SQL shaped
> cursor.
> The really interesting thing is that opening WISQL on another *server* box
> (this one running W2000, IB5.6) and attempting to connect to the database
> *is* successful.
> When the "offending" application, on one of the clients, is killed, via

task

> manager, everthing is all of the sudden fine and working as expected.
> The only thing in the Interbase.log file are the (expected) 10054's from

the

> application that was forcefully killed.
> Any ideas about what is going on?
> IB appears fine, the engine itself, based on the fact that I can connect
> locally via WISQL and do whatever I want in/to the database.
> It appears that some "driver" level network layer is "locked" until the
> offending (whatever the heck it's doing) application is killed.
>
>
> Best regards,
> Fred Wilson
> SE, Bell & Howell
> fred.wilson@...
>
>
>
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