August 24, 2011 at 12:34 am
Greetings,
Can someone explain the wait event "PREEMPTIVE_OS_WAITFORSINGLEOBJEC" for me?
There is a nightly batch that is running against one of our databases and it has now been stopping every night on the same query.
When running the procedure "sp_WhoIsActive" I can see that it is in a running status but with the wait_info "PREEMPTIVE_OS_WAITFORSINGLEOBJEC". This database version we are running is SQL Server 2008 R2 Standard Edition.
In case it helps then here is some of the sp_WhoIsActive information. Copy/paste the below to excel displays it better.
wait_infoCPUtempdb_allocationstempdb_currentblocking_session_idreadswritesphysical_readsused_memorystatusopen_tran_countpercent_completehost_namedatabase_nameprogram_namestart_timelogin_timerequest_idcollection_time
(1342ms)PREEMPTIVE_OS_WAITFORSINGLEOBJEC 47 33,184 31,720NULL 63 0 0 51,247runnable 0NULL[Servername][DatabaseName].Net SqlClient Data Provider2011-08-24 03:10:00.6832011-08-24 01:06:33.65002011-08-24 09:31:16.440
Thanks in advance!
June 13, 2014 at 10:03 am
I know this is an old post but I came across it through a Bing search (don't hold it against me :w00t: ).
Anyway for those that may come across this in searching for "PREEMPTIVE_OS_WAITFORSINGLEOBJECT", I came across this article from Michael Swart: "Be Quick About Reading The Data You Asked For[/url]".
A lot of the "preemptive_xx" waits in SQL Server are only documented through blog post. Through reading bits and pieces of BOL where "preemptive" comes up I understand that "preemptive" is something with the operating system or external to SQL Server. So SQL Server is basically waiting on something outside of its control before it can keep going. The article from Michael Swart suggest that seeing this particular wait type along with "ASYNC_NETWORK_IO" can be an indication that SQL Server is waiting on a client to process the data it is getting from the database.
I have learned that with waits it is important to not necessarily focus on just one, as seeing some along with others can mean more than just seeing one particular wait type frequently. Along with the fact that some are just going to happen and it is not necessarily a bad thing every time.
Shawn Melton
Twitter: @wsmelton
Blog: wsmelton.github.com
Github: wsmelton
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