SQL Server: how to acquire exclusive lock to prevent race condition?

I'm not exactly sure what you are trying to do from the posted code. I presume you are just trying to serialize access to that piece of code? If so sp_getapplock should do what you need instead of creating a new dummy table that you just use to take locks on.

You can use the locking hint WITH(XLOCK, ROWLOCK) within the scope of a transaction with Repeatable Read isolation. At Serializable isolation the exclusive lock is obtained by default on a read operation, so if you needed a particular transaction to play nice in parallel, you could specify an increased serialization level for that one transaction when creating it (which you are doing; this isn't a hack, just the way things are done depending on the situation).

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