Find the Objects That Have the Most Locks Taken on Them

Database administrators often need to identify the source of locks that are hindering database performance.

For example, you are monitoring your production server for any possible bottlenecks. You suspect that there might be highly contested resources, and would like to know how many locks are taken on those objects. Once the most frequently locked objects are identified, steps can be taken to optimize access to the contended objects.

To do this, use Query Editor in SQL Server Management Studio.

To find the objects that have the most locks

• In Query Editor, issue the following statements.

  -- Find objects in a particular database that have the most
  -- lock acquired. This sample uses AdventureWorksDW2012.
  -- Create the session and add an event and target.
  -- 
  IF EXISTS(SELECT * FROM sys.server_event_sessions WHERE name='LockCounts')
  DROP EVENT session LockCounts ON SERVER
  GO
  DECLARE @dbid int
  
  SELECT @dbid = db_id('AdventureWorksDW2012')
  
  DECLARE @sql nvarchar(1024)
  SET @sql = '
  CREATE event session LockCounts ON SERVER
  ADD EVENT sqlserver.lock_acquired (WHERE database_id =' + CAST(@dbid AS nvarchar) +')
  ADD TARGET package0.histogram( 
  SET filtering_event_name=''sqlserver.lock_acquired'', source_type=0, source=''resource_0'')'
  
  EXEC (@sql)
  GO
  ALTER EVENT session LockCounts ON SERVER 
  STATE=start
  GO
  -- 
  -- Create a simple workload that takes locks.
  -- 
  USE AdventureWorksDW2012
  GO
  SELECT TOP 1 * FROM dbo.vAssocSeqLineItems
  GO
  -- The histogram target output is available from the 
  -- sys.dm_xe_session_targets dynamic management view in
  -- XML format.
  -- The following query joins the bucketizing target output with
  -- sys.objects to obtain the object names.
  --
  SELECT name, object_id, lock_count FROM 
  (SELECT objstats.value('.','bigint') AS lobject_id, 
  objstats.value('@count', 'bigint') AS lock_count
  FROM (
  SELECT CAST(xest.target_data AS XML)
  LockData
  FROM sys.dm_xe_session_targets xest
  JOIN sys.dm_xe_sessions xes ON xes.address = xest.event_session_address
  JOIN sys.server_event_sessions ses ON xes.name = ses.name
  WHERE xest.target_name = 'histogram' AND xes.name = 'LockCounts'
  ) Locks
  CROSS APPLY LockData.nodes('//HistogramTarget/Slot') AS T(objstats)
   ) LockedObjects 
  INNER JOIN sys.objects o
  ON LockedObjects.lobject_id = o.object_id
  WHERE o.type != 'S' AND o.type = 'U'
  ORDER BY lock_count desc
  GO
  -- 
  -- Stop the event session.
  -- 
  ALTER EVENT SESSION LockCounts ON SERVER
  state=stop
  GO
  

After the statements in this procedure finish, the Results tab of Query Editor displays the following columns:

• name

• object_id

• lock_count

See Also

Reference

CREATE EVENT SESSION (Transact-SQL)

ALTER EVENT SESSION (Transact-SQL)

sys.dm_xe_session_targets (Transact-SQL)

sys.dm_xe_sessions (Transact-SQL)

sys.server_event_sessions (Transact-SQL)