Subject Deadlock Occuring with Concurrent Transactions
Author imtiaz_ally
When I try to execute a Stored procedure simultaneaously (by the
same application located on 2 different PCs on a LAN), I get a
deadlock Exception from one instance of the application while the
other one successfully proceeds. The application is compiled on .NET
2.0 using the the IB Free OLEDB 1.5 Driver accessing a Firebird 1.5.3
DB on a Windows 2003 server on a LAN.
I really need BOTH transactions to proceed (even if ONE
waits) and WITHOUT my application getting an exception i.e. the DBMS
killing the transaction completely because of locking, instead of waiting.

At first I thought it was an OLE DB Driver problem and when
I tried to upgrade to the latest version and/or setting Isolation
levels in .NET, this does not reslove the problem at all. Then, I
tried to see the Firebird Config file to see about Deadlock params,
but I did not find anything interesting. Finally, I made the same test
but by executing the SP straight from a SQL Window in IBExpert (on the
same 2 PCs & simultaneously), and again I got this Deadlock error on 1
PC while the other 1 successfully proceeds (see below):

"Unsuccessful execution caused by system error that does not preclude
successful execution of subsequent statements.
lock conflict on no wait transaction.
update conflicts with concurrent update."

Can you please help me in understanding & solving the problem??? Thank

Platform : WinXP/2003 - FireBird 1.5.3