Estos dos queries son muy útiles a lo hora de detectar un bloque.
Una manera rápida de saber si estamos teniendo bloqueos es consultar sys.dm_os_schedulers, si tenemos un valor mayor a 10 en la columna current_tasks_count, es casi seguro de que estamos teniendo bloqueos en nuestra base de datos.
SELECT scheduler_id, current_tasks_count, runnable_tasks_count
FROM sys.dm_os_schedulers
WHERE scheduler_id < 255
SELECT t1.resource_type AS 'lock type',db_name(resource_database_id) AS 'database',
t1.resource_associated_entity_id AS 'blk object',t1.request_mode AS 'lock req', --- lock requested
t1.request_session_id AS 'waiter sid', t2.wait_duration_ms AS 'wait time',
(SELECT [text] FROM sys.dm_exec_requests AS r
CROSS APPLY sys.dm_exec_sql_text(r.sql_handle)
WHERE r.session_id = t1.request_session_id) AS 'waiter_batch',
(SELECT substring(qt.text,r.statement_start_offset/2,
(CASE WHEN r.statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max), qt.text)) * 2
ELSE r.statement_end_offset END - r.statement_start_offset)/2)
FROM sys.dm_exec_requests AS r
CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) AS qt
WHERE r.session_id = t1.request_session_id) AS 'waiter_stmt',
t2.blocking_session_id AS 'blocker sid',
(SELECT [text] FROM sys.sysprocesses AS p
CROSS APPLY sys.dm_exec_sql_text(p.sql_handle)
WHERE p.spid = t2.blocking_session_id) AS 'blocker_stmt'
FROM sys.dm_tran_locks AS t1
INNER JOIN sys.dm_os_waiting_tasks AS t2
ON t1.lock_owner_address = t2.resource_address
Este query nos puede dar información adicional.
SELECT t1.resource_type, t1.resource_database_id,
t1.resource_associated_entity_id,t1.request_mode,
t1.request_session_id,t2.blocking_session_id
FROM sys.dm_tran_locks AS t1
INNER JOIN sys.dm_os_waiting_tasks AS t2
ON t1.lock_owner_address = t2.resource_address;