Waitopedia is a comprehensive resource of information about SQL Server waits.

The description shown below is the top answer as voted by the Spotlight community.

The charts are based on 2.1 TB of data collected from 4207 instances uploaded by 323 Spotlight users over an 8 week period.


Category: Idle
SQL Server versions: 2005, 2008, 2008 R2, 2012, 2014, 2016, 2017

This is an idle wait and so it can be safely ignored.


1 Answer


Occurs while a query waits for its request for a thread reservation to be fulfilled. It also occurs when synchronizing query compile and memory grant requests. Information from Microsoft®

Very rare

This wait never occurs for most instances

For each of 4207 instances, we ranked RESOURCE_SEMAPHORE_MUTEX on how frequent it is compared to all other recent waits. The chart shows the total of all rankings.

Prevalence of RESOURCE_SEMAPHORE_MUTEX across the Spotlight Population

For 82 % of hours with this wait, average wait time is less than 0.06 ms

For each instance, we found all the recent hours when it had a RESOURCE_SEMAPHORE_MUTEX wait. We found the average latency for each of those hours.

385 instances contributed data to this chart

Latency Distribution of RESOURCE_SEMAPHORE_MUTEX across the Spotlight Population