SQL Server introduces various locks.

Introduction to locking in SQL Server

Http://www.sqlteam.com/article/introduction-to-locking-in-sql-server

 

SQL Server also has an object called latch. SQL Server provides a performance counter to monitor a resource lock called latches in SQL Server. by monitoring latches, you can determine your activity and resource usage, which helps us identify performance bottlenecks.

 

The following is the counters of latch.

• Average latch wait time (MS)
• Latch waits/sec
• Total latch wait time (MS)

For more information, see

SQL Server: latches object

Http://msdn.microsoft.com/en-us/library/aa905135%28SQL.80%29.aspx