(Republishing, or using this info in a commercial product/website, is prohibited without permission. All other uses are permitted. If in doubt, please ask.)
Description:
This wait type is when a thread is waiting for exclusive access to a trace buffer in preparation for writing it to a trace file.
(Books Online description: “Occurs during synchronization on trace buffers during a file trace.”)
Questions/comments on this wait type? Click here to send Paul an email, especially if you have any information to add to this topic.
Added in SQL Server version:
2008 R2
Removed in SQL Server version:
N/A
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 161 in 2008 R2, and 165 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 wait type be a noticeable contention point.
Known occurrences in SQL Server (list number matches call stack list):
- Getting access to a trace buffer before writing it to a trace file
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):
- SOS_Task::PostWait+90
EventInternal<SuspendQueueSLock>::Wait+1f9
CTraceFileIoProviderAccess::GetExclusiveAccess+13f
CTraceWriteRequest::InitForFileTrace+6b
CTraceFileIoProvider::InitializeWriteRequest+29
CTrace::WriteRecord+74e
CTraceController::ProduceRecord+706
CQScanSortNew::TransitionToOutputPhase+187
CQScanSortNew::PushClose+36
CQScanSortNew::BuildSortTable+2ec
CQScanSortNew::OpenHelper+c0
CQScanNew::OpenHelper+41
CQScanStreamAggregateNew::Open+30
CQScanNew::OpenHelper+41
CQScanXProducerNew::Open+c8
FnProducerOpen+44
FnProducerThread+851
SubprocEntrypoint+a59
SOS_Task::Param::Execute+21e
SOS_Scheduler::RunTask+a8