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Asked: 2026-05-15T03:00:29+00:00

I am using SQL Server 2008 Enterprise. I am wondering whether dead lock issue

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I am using SQL Server 2008 Enterprise. I am wondering whether dead lock issue is only caused by cross dependencies (e.g. task A has lock on L1 but waits on lock on L2, and at the same time, task B has lock on L2 but waits on lock on L1)? Are there any other reasons and scenarios which will cause deadlock?

Are there any other way which will causes dead lock — e.g. timeout (a S/I/D/U statement do not return for a very long time, and deadlock error will be returned) or can not acquire lock for a long time but not caused by cross-dependencies (e.g. task C needs to get lock on table T, but another task D acquire the lock on table T without releasing the lock, which causes task C not be able to get lock on table T for a long time)?

EDIT 1: will this store procedure cause deadlock if executed by multiple threads at the same time?

create PROCEDURE [dbo].[FooProc]    
(  
 @Param1 int 
 ,@Param2 int  
 ,@Param3 int  
)    
AS    

DELETE FooTable WHERE  Param1 = @Param1     

INSERT INTO FooTable    
 (  
 Param1  
 ,Param2  
 ,Param3  
  )    
 VALUES    
 (  
 @Param1  
 ,@Param2  
 ,@Param3  
  )    

DECLARE @ID bigint    
 SET @ID = ISNULL(@@Identity,-1)    
 IF @ID > 0    
 BEGIN    
      SELECT IdentityStr FROM FooTable WHERE ID = @ID 
 END

thanks in advance,
George

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1 Answer

  1. Editorial Team

    Deadlocks require a cycle where resources are locked by processes that are waiting on locks held by other processes to release the locks. Any number of processes can participate in a deadlock, and the normal method for detecting deadlocks is to take a graph of the dependencies on the locks and search for cycles in that graph.

    You need to have that cycle for a deadlock to exist. Anything else is just a process held up waiting for a lock to be released. A quick way to see what processes are being blocked by others is sp_who2.

    If you want to troubleshoot deadlocks, the best way is to run a trace, picking up ‘deadlock graph’ events. This will allow you to see what’s going on by telling you what queries are holding the locks.

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