Getting worker thread IDs using DMVs

In SQL 2000, the kpid column in sysprocesses was a convenient way to find out the actual worker thread ID (OS level thread identifier) for a given task. How does one do this using the DMVs?

Here is a quick way:

select R.Session_Id, Th.os_thread_id from sys.dm_exec_requests R
join sys.dm_exec_sessions S on R.session_id = S.session_id
join sys.dm_os_tasks T on R.session_id = T.session_id
join sys.dm_os_workers W on T.worker_address = W.worker_address
join sys.dm_os_threads Th on W.thread_address = Th.thread_address
where S.is_user_process = 1
order by Session_id

The above script will get you the session ID and thread ID for any tasks currently running, and will also filter out any non-user processes. BUT… my hand-written T-SQL looks so crowded and ugly. Let us format it with the T-SQL formatting script I shared a while back on my blog:

SELECT R.Session_Id,
FROM   sys.dm_exec_requests AS R
sys.dm_exec_sessions AS S
ON R.session_id = S.session_id
sys.dm_os_tasks AS T
ON R.session_id = T.session_id
sys.dm_os_workers AS W
ON T.worker_address = W.worker_address
sys.dm_os_threads AS Th
ON W.thread_address = Th.thread_address
WHERE  S.is_user_process = 1;

Looks a lot easier to read! Now, by switching the last is_user_process flag to 0, you can switch to viewing the OS thread IDs of system processes. In the next post, I will show you how to use this knowledge and information to dig even deeper and view the operation of system threads like the lazy writer. Stay tuned!


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