sys.dm_os_tasks

Question

sys.dm_os_tasks

sudhakara

SSCrazy Eights

Points: 9425
More actions
September 29, 2017 at 11:19 am

#325566

Hello everyone,
some of the tasks from this dmv are appearing with session_id null which are connected with workers. Can someone explain me how task can be associated with worker without any session id ??
SELECT dot.*
FROM sys.dm_os_workers dow,
sys.dm_os_tasks dot
where dow.worker_address= dot.worker_address
and dot.session_id is NULL

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Sue_H SSC Guru Points: 90860 More actions · Answer 1

sudhakara - Friday, September 29, 2017 11:19 AM
Hello everyone,
some of the tasks from this dmv are appearing with session_id null which are connected with workers. Can someone explain me how task can be associated with worker without any session id ??
SELECT dot.*
FROM sys.dm_os_workers dow,
sys.dm_os_tasks dot
where dow.worker_address= dot.worker_address
and dot.session_id is NULL

System tasks don't necessarily have a session id.

Sue

sudhakara SSCrazy Eights Points: 9425 More actions · Answer 2

Sue_H - Friday, September 29, 2017 1:16 PM
sudhakara - Friday, September 29, 2017 11:19 AM
Hello everyone,
some of the tasks from this dmv are appearing with session_id null which are connected with workers. Can someone explain me how task can be associated with worker without any session id ??
SELECT dot.*
FROM sys.dm_os_workers dow,
sys.dm_os_tasks dot
where dow.worker_address= dot.worker_address
and dot.session_id is NULL
System tasks don't necessarily have a session id.
Sue

Thank you for your input Sue.

As session ids are already reserved till 50 for system related tasks then what kind system tasks are being performed here?

Sue_H SSC Guru Points: 90860 More actions · Answer 3

sudhakara - Monday, October 2, 2017 9:58 AM
Thank you for your input Sue.
As session ids are already reserved till 50 for system related tasks then what kind system tasks are being performed here?

If you are not on SQL Server 2000 or less, Session ids less than 50 are not reserved for system tasks. And system tasks can be greater than 50 as well.

Sue