TCode - SM12 (Lock Management)
Enqueue table size is defined by the parameter
Enqueue/table_size=4MB (Earlier 1 MB to 4 MB) in Netweaver systems this can be increased to 100MB
Locks are monitored in transaction SM12. In principle the lock which are older than one hour should be reported to the escalation manager. If the lock table is filled (Enque/ Table_size) an overflow occurs in the lock table.
1. Check whether the update server is still performing the updates. If the updating has stopped, then the lock table can quickly become over filled with the locks held by update requests. We can resolve the problem by restarting the updates. If updating has not been interpreted, then we must enlarge the lock table.
Note: Enque table overflow is recorded in SM21 and ST22
Eg: Execute SU01 from Shawn user/ 800 and edit shramana user
Execute SU01 from Shawn user/800 and edit shramana user
Following message is displayed
And now execute SM12 which displays the Exclusive Mode lock
2. Enque time is too high
As a part of the response time enqueue time should be 1ms - 5ms for Central instance and 100Ms in case of the request that is coming form Dialogue instance.
Then we can consider the following
1. Lock table is overflow and the locks are held in SM12
2. Update is deactivate (SM14) due to any of the issues in DB. If the update gets deactivated then the locks are not released.
3. If the Enqueue time increases i.e. there could be RFC issue or Enque wait time is increasing then consider increasing Enqueue work processes.
4. Dead locks (Usually never occurs, but there is a collision between PP, Manufacturing and Material Module, so highlight this issue to SAP)
In some instances we may need to release the locks but we need to follow certain process.
Do not release the lock in SM12 (Even though there is an option)
Lock deletion is recorded in SM21.
1. Users complaint that he could not update a record and message pop up stating that the record is locked by user XYZ.
2. Check the period of lock (if it is older than 1 hour inform to the escalation manager)
3. Get the written B&W approval from the user and terminate the session of that user using SM04. (Only Terminate or End that session)
All the transaction activities are recorded in CDHDR
Note: Initially 20Kb Mem is given from ztta_roll_first.
We may need to allow some locks for more than one hour or days (Eg. Payroll update processing) consumes lot of time. We need to ensure that dialogue process should not held for longer time, but however BTC is allowed.
You can also get information regarding SAP BASIS