Exclusive Application Lock

Get Exclusive Application Lock: 

DECLARE @ProcResult int = 0;

-- Get an exclusive application lock on the package execution resource, to prevent other executions of the same package from doing the same

EXEC @ProcResult = sp_getapplock @Resource = @PackageResourceName,

                                 @LockMode = 'Exclusive',

                                 @LockOwner = 'Session',

                                 @LockTimeout = 0; -- Do not wait for the lock

IF @ProcResult < 0

    RAISERROR('Failed to acquire application lock on %s. sp_getapplock returned %d', 16, 1, @PackageResourceName, @ProcResult);

Here @PackageResourceName is a string specifying a name that identifies the lock resource. The application must ensure that the resource name is unique. The specified name is hashed internally into a value that can be stored in the SQL Server lock manager

Release Exclusive Application Lock: 

DECLARE @ProcResult int = 0;

-- Release a previously acquired exclusive application lock on the package execution resource

EXEC @ProcResult = sp_releaseapplock @Resource = @PackageResourceName,

                                    @LockOwner = 'Session';

IF @ProcResult < 0

RAISERROR('Failed to release application lock on %s. sp_releaseapplock returned %d', 16, 1, @PackageResourceName, @ProcResult);

Make sure the "RetainSameConnection" property on the Database connection manager  ( used to execute the above commands) is set to True.