DEADLOCK_ENUM_MUTEX and SQL Server Data Collector

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I recently implemented the Performance Datawarehouse on our production server 
after running it in our test environment for months with no problems. I am 
currently only collecting the 3 basic collection sets. Today 2 'SQL Server 
Data Collector' spids got hung and will not rollback. Normally the collection 
jobs take about 1.5minutes according to the log. Today though, the 
QueryStatisticscollection job was running for over 30minutes and causing the 
ActivityMonitor to error. I stopped the collection sets and the associated 
jobs. This did nothing to alleviate the problem. The spids that are hung are 
reporting a lastwaittype of 'DEADLOCK_ENUM_MUTEX'--they are in a 
'killed/rollback' state but are not doing so. This waittype means: Occurs 
when the deadlock monitor and sys.dm_os_waiting_tasks try to make sure that 
SQL Server is not running multiple deadlock searches at the same time.

I have read the article 'Troubleshooting the Data collector' 
( but it has not 
really helped. There are no errors in the Datacollector logs. It appears that 
the same collection set is running twice when viewing the logs  and has not 
stopped and the spids are not rolling back. I have searched for any 
dcexec.exe processes running on the server as well as any of the 
Datacollector SSIS packages running and there are none.

Is there a way for these spids to die gracefully? I can't really stop and 
start the sql agent at this time which I suspect may be one way to do this. 
These spids appear to be causing issues when trying to use the 
ActivityMonitor since it uses the sys.dm_os_waiting_tasks DMV to show data. 
Any suggestions would be helpful! Thank you! 

Reply Utf 3/26/2010 8:11:01 PM

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