Rollback transaction in CreateInstance stored proc to prevent deadlocks (#218)

Co-authored-by: RAMAKANT BHANDARU <[email protected]>

Author: microrama

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Updates
 
 * Replace hardcoded version string + globs with build variables ([#213](https://github.com/microsoft/durabletask-mssql/pull/213))
+* Fix deadlock issue on orchestration creation ([#218](https://github.com/microsoft/durabletask-mssql/pull/218)) - contributed by [@microrama](https://github.com/microrama)
 
 ## v1.2.3
 

src/DurableTask.SqlServer/Scripts/logic.sql

@@ -260,6 +260,7 @@ BEGIN
         IF @existingStatus IN (SELECT value FROM STRING_SPLIT(@DedupeStatuses, ','))
         BEGIN
             DECLARE @msg nvarchar(4000) = FORMATMESSAGE('Cannot create instance with ID ''%s'' because a pending or running instance with ID already exists.', @InstanceID);
+            ROLLBACK TRANSACTION;
             THROW 50001, @msg, 1;
         END
         ELSE IF @existingStatus IS NOT NULL