Locks

Display this screen by using the transaction DBACOCKPIT and navigating to Performance → Locks.

The Locks entrance screen is divided in the sub screens Blocking Locks and All Locks. You can switch between both sub screens with the corresponding tab-riders.

Blocking Locks are wait situations that are currently caused by database locks. Normally, no data is displayed here. You see the following message: No blocking locks found.

The All Locks screen lists all the locks that are currently maintained by the server..

Features

A user holding a lock occupies an SAP work process. If other users attempt to apply the same lock, these users have to wait. During this time, these users occupy their own SAP work process. This waiting for a lock is known as a lock wait. Since the number of lock waits increases, the available SAP work processes can process fewer and fewer SAP user requests. In the worst case, that is when the number of lock waits equals the number of SAP work processes, a small number of users can cause the entire SAP system to freeze.

If exclusive lockwaits occur, both blocking and blocked processes are displayed. For each blocking situation, a tree of waiting processes is shown. Column SID shows the session ID of the process. Column Blocking SID shows the session ID of the blocking process.

To display the SQL statement on the database, mark a row and then choose SQL statement.

When choosing the All Locks tab, a button becomes visible. When pressed it lists all locks on the server. This can be time consuming if many locks are held.