(Republishing, or using this info in a commercial product/website, is prohibited without permission. All other uses are permitted. If in doubt, please ask.)
This wait type is when a thread is waiting for access to a thread-safe memory object used during query execution by the Query Execution portion of the Query Processor.
(Books Online description: “Occurs during synchronization of certain types of memory allocations during statement execution.”)
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:
Removed in SQL Server version:
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 280 in 2008 and 2008 R2, 287 in 2012, and 294 in 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.
I have not seen this wait type be a noticeable point of contention.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for access to a memory object (in this case, while allocating memory to hold details of columns while sending TDS column formats to a client)
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):