Measure Internal Latch Contention with sys.dm_os_latch_stats

Wed, 21 Oct 2026 00:00:00 +0000

When LATCH_* waits show up near the top of sys.dm_os_wait_stats, you know threads are waiting on non-buffer latches. You don't know which engine structure they're waiting for. sys.dm_os_latch_stats splits those waits by latch class. The script below ranks the non-buffer classes that make up the first 95% of latch wait time and returns the seconds waited, the wait count, the percentage and the average wait for each class.

Purpose and Overview

The job is to turn a generic latch wait into a named structure, such as a filegroup, the log manager or the root of a B-tree. Non-buffer latch waits appear in wait stats as a LATCH_* wait type, and once they appear, sys.dm_os_latch_stats gives the cumulative breakdown by class. A latch wait starts when a request cannot be granted immediately because another thread holds the latch in a conflicting mode.

Latches on SQL Server Scripts

Measure Internal Latch Contention with sys.dm_os_latch_stats

Purpose and Overview