Scheduler appears deadlocked due to a large number of worker threads

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Scheduler appears deadlocked due to a large number of worker threads

Benki Chendu

SSCrazy Eights

Points: 8051
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December 13, 2011 at 8:32 am

#253463

I am seeing a lot of these messages in sql server error logs
2011-12-11 03:27:34.15 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
2011-12-11 03:45:29.17 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
2011-12-11 03:48:44.17 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
I was all these days under the impression that if worker threads are high, CPU spikes which will bring the server to a stand still..But here in this case, CPU utilization is only 3%
I would need some help in understanding this error message

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SpringTownDBA SSCertifiable Points: 6917 More actions · Answer 1

itsamarnath (12/13/2011)
I am seeing a lot of these messages in sql server error logs
2011-12-11 03:27:34.15 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
2011-12-11 03:45:29.17 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
2011-12-11 03:48:44.17 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
I was all these days under the impression that if worker threads are high, CPU spikes which will bring the server to a stand still..But here in this case, CPU utilization is only 3%
I would need some help in understanding this error message

http://blogs.msdn.com/b/grahamk/archive/2011/01/10/sql-server-blocking-caused-by-database-mirroring-wait-type-dbmirror-dbm-event.aspx/

Your mirror can't keep up with the principal.

Devendrakumar SSC-Forever Points: 42493 More actions · Answer 2

It also means you it will take much time to failover or you may lose data in forced failover.

It’s a serious issue. Please verify the mirroring states.

http://msdn.microsoft.com/en-us/library/ms189284.aspx

The following article is useful to estimate failover.

http://msdn.microsoft.com/en-us/library/ms187465.aspx

Divine Flame SSCoach Points: 15943 More actions · Answer 3

itsamarnath (12/13/2011)
I am seeing a lot of these messages in sql server error logs
2011-12-11 03:27:34.15 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
2011-12-11 03:45:29.17 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
2011-12-11 03:48:44.17 Server All schedulers on Node 0 appear deadlocked due to a large number of worker threads waiting on DBMIRROR_DBM_EVENT. Process Utilization 3%.
I was all these days under the impression that if worker threads are high, CPU spikes which will bring the server to a stand still..But here in this case, CPU utilization is only 3%
I would need some help in understanding this error message

Your mirror server is not able to keep up with the principle server. How many databases are involved in the mirroring?

Does your mirror server have the same configuration as the principle ? If not, you need to think about that.

Sujeet Singh

Benki Chendu SSCrazy Eights Points: 8051 More actions · Answer 4

3 databases are in mirroring.

And every time these errors are logged, the website which is using this sql instance goes down and sql becomes unreachable..Finally, we are actually restarting the sql instance.