Dear All,
I have been asked to investigate a strange issue we are encountering at a
customer site in Mexico. I am a contractor for a company which supplied
surveillance and monitoring software based on the ICS component set. The
software runs fine on other sites with no problems encountered for over 8
months but on the site in Mexico after a matter of hours or days the
software (and or server) crashes.
My analysis of the problem to date suggests that an OnClientConnect is
firing but the passed Client object is incomplete or invalid. The code for
the OnClientConnect event does not check the ErrorCode and accepts the
connection but traffic appears not to flow correctly between client and
server. Eventually the connection is terminated and the client attempts to
reconnect again. This sequence is repeated and on each occasion if I run
NetStat on the server it appears a windows socket object is left in FIN-WAIT
1 or FIN-WAIT2 state. Eventually the system fails as all windows socket
objects are expended and there is a catastrophic failure of the software
and/or server.
The servers are all identical HP Blade servers running Windows Server 2003
vanilla installs. This is true of sites that are functioning and the ones in
Mexico that are not.
The code in the OnClientConnect event handler does the following
procedure TAraliaSocketServer.DoClientConnect( Sender : TObject;
Client : TWSocketClient;
Error : Word );
const
ProcName = 'DoClientConnect';
var
LList : TList;
LSocketObject : TSocketObject;
begin
try
WriteLog( 'ACCEPTING CONNECTION FROM ' + Client.GetPeerAddr + ':' +
Client.GetPeerPort );
WriteLog( 'ADDING TO LIST ' + Client.GetPeerAddr + ':' +
Client.GetPeerPort );
FListOfConnections.Add(TSocketObject(Client));
Client.OnError := DoClientError;
Client.OnDataAvailable := DoClientDataAvailable;
Client.OnDataSent := DoClientDataSent;
Client.OnBGException := DoServerBGException;
DoClientConnection( TSocketObject(Client), True );
except on E : Exception do ComponentException( ProcName, E );
end;
end;
Reviewing the log of the above in the cases where the software is working
correctly the calls to GetPeerAddr and GetPeerPort result in valid ipaddress
and port number and in the error scenario they are always null strings. I
assume the Error code is significant and should be checked so I am wondering
what are the permissible values and the steps that should be taken when an
error does occur to ensure that the windows sockets are correctly 'cleaned
up' and released back to the Operating System ?
Has anyone encountered issues such as this and if so was an underlying cause
identified ? Network / NIC hardware fault or other....
Any help on this point would be very gratefully received as no progress has
been made for several months due to a lack of ability to 'reproduce' the
problem and the lack of permission to test and debug on the customer site.
Best regards,
Damien.
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