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Description:
This latch class is when a thread is waiting for access to the structure within Service Broker that maps services to brokers.
(Books Online description: “Internal use only.”)
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Added in SQL Server version:
pre-2005/2005
Removed in SQL Server version:
N/A
Extended Events latch_class value:
Maps to the SSB_MAPPING_MANAGER map_value in sys.dm_xe_map_values.
The map_key value in sys.dm_xe_map_values is 95 in 2008 and 2008 R2, and 92 in 2012 and 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.
Other information:
I have not seen this latch be a contention point.
Known occurrences in SQL Server (list number matches call stack list):
- Getting access to the mapping table (in this case, when shutting down a broker for a database that has the AUTO_CLOSE option set)
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):
- LatchBase::Suspend+16b8
LatchBase::AcquireInternal+415
CSbMappingMgr::NotifyBrokerShutDown+dd
CActiveServiceBroker::Shutdown+2f2
CActiveServiceBrokerMgr::NotifyDbShutdown+4d
DBTABLE::Shutdown+1e0
DBMgr::ShutdownDB+208
DBMgr::CleanShutdownDB+51c
TaskDatabaseAutoClose::ProcessTskPkt+386
OnDemandTaskContext::ProcessTskPkt+3e2
SystemTaskEntryPoint+426
OnDemandTaskContext::FuncEntryPoint+25
SOS_Task::Param::Execute+21e
SOS_Scheduler::RunTask+ab