Wednesday, 4 December 2013

What is lock table over flow ? How to resolve lock table overflow issue ?




  • What is lock table overflow ?
  • How to identify lock table over flow issue ?
  • What is the parameter to be changed to increase lock table size in SAP ?
  • What is the reason for lock table overflow ?
  • How to resolve lock table overflow ?

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What is lock table overflow ?

SAP manages locks using lock table. The lock table contains all of the informaton related to locks like who is holding the lock and which locks are currently held etc. The size of the lock table can be specified by the SAP parameter enque/table_size. The size of the lock table limits the number of locks, lock owners and lock names. If this size is exceeded, then the lock table overflow occurs.

How to identify lock table overflow issue ?

In SM21 transaction log and ST22 dumps, if you find any error messages like LOCK_TABLE_OVERFLOW, Lock table overflow, Internal lock administration error it means there is a lock table overflow issue.


What is the parameter to be changed to increase lock table size in SAP ?

Parameter enque/table_size to be changed to increase or decrease lock table size using RZ10 transaction. Default value of this parameter is 32768. The min value that can be set is 4096 and max value is 102400. The unit for this parameter is KB.



As this is not dynamic parameter, for the new value to take effect, a system restart is required after modifying the parameter.

What is the reason for lock table overflow ?

A lock table overflow can occur due to

  • The lock table is configured too small (i.e value set to enque/table_size parameter is very low)

  • Due to improper design of application which sets a large number of locks

  • Number of enqueue worprocesses configured in a sap system are less and update is very slow/hanging due to which lots of locks are accumulated in lock table

  • Running a custom report with improper selection criteria (like very long time periods data pull) which sets so many locks & eventually lock table overflow occurs

 How to resolve lock table overflow ?

  • Increase the size of lock table i.e increase the parameter enque/table_size value using RZ10 transaction.
          To determine the optimal value for this parameter, you can check the maximum locks set so far in the history and the current number of locks set from SM12 -> Extras -> Statistics

  • Increase the number of en-queue work-processes

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