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SOS_WORK_DISPATCHER

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Description:

This wait type is where a thread in SQLOS is waiting for something to do. This wait starts when the thread becomes idle and stops when the thread is given some work to do.

(Books Online description: N/A)

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:

Azure SQL Database

Removed in SQL Server version:

N/A

Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 172 as of May 2018. You must check the DMV to get the latest value as some map_key values have changed in later builds.

Other information:

This wait type is one that I usually filter out as a benign wait when doing wait statistics analysis. It will usually show up as the top wait on Azure SQL Database and SQL Server 2019 and can be safely ignored. A blog post with an investigation into this wait is here.

Known occurrences in SQL Server (list number matches call stack list):

  1. Waiting for some work to do

Abbreviated call stacks (list number matches known occurrences list):

  1. SOS_Task::PostWait+0x6f
    WaitableBase::Wait+0x19c
    WorkDispatcher::DequeueTask+0x5de
    SOS_Scheduler::ProcessTasks+0x234
    SchedulerManager::WorkerEntryPoint+0x2a1
    SystemThread::RunWorker+0x91
    SystemThreadDispatcher::ProcessWorker+0x2f3
    SchedulerManager::ThreadEntryPoint+0x1e5