About Lock Entries and Lock Table Overflow

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Transcript of About Lock Entries and Lock Table Overflow

About Lock Entries and Lock Table Overflow

Applies to:SAP NetWeaver BW 3.x. For more information, visit the EDW homepage.

SummaryThis article explains about the error Lock Table Overflow" encountered when the specified limit of Lock entries maintained with the Parameter enque/table_size which determines the size of the lock table in KB is Overflown.Articles briefs about the error Lock Table Overflow encountered when trying to collect large set of Objects to a Transport Request. Author: Rudra Pradeep Reddy Neelapu

Company: Deloitte Consulting Created on: 1 January 2011

Author BioWorking as a BI Consultant with Deloitte Consulting India Pvt.Ltd., Skill set includes SAP Business Intelligence, ABAP and Business Objects.

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About Lock Entries and Lock Table Overflow

Table of ContentsIntroduction ......................................................................................................................................................... 3 Background Information...................................................................................................................................... 3 Lock Concept .................................................................................................................................................. 3 Lock Table ....................................................................................................................................................... 3 Use.. ............................................................................................................................................................ 3 Subsequent Analysis of Lock Table Overflows .................................................................................................. 3 About Lock Table Overflow error ........................................................................................................................ 3 Maintaining the Profile Parameter ...................................................................................................................... 8 Reason and Prerequisites for Lock Table Overflow ......................................................................................... 10 Lock management ............................................................................................................................................ 10 Diagnosis ...................................................................................................................................................... 11 Diagnosis in update....................................................................................................................................... 11 Statistics ........................................................................................................................................................ 13Features ..................................................................................................................................................................... 13

Activities ............................................................................................................................................................ 14 Total Capacity Used ...................................................................................................................................... 14Current ....................................................................................................................................................................... 14 History ........................................................................................................................................................................ 14 Delete History ............................................................................................................................................................ 14

Related Content ................................................................................................................................................ 15 Disclaimer and Liability Notice .......................................................................................................................... 16

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About Lock Entries and Lock Table Overflow

IntroductionThe error Lock Table Overflow is encountered when the configured lock table limit is too small. Lock entries are maintained with the Parameter enque/table_size. Parameter enque/table_size determines the size of the lock table in KB. This articles explains the scenario of Lock Table Overflow encountered when trying to collect large set of Objects to a Transport Request and steps taken to address the issue with the help of BASIS team. Before going ahead lets have brief information about Lock Entry and Lock Table concepts.

Background InformationLock Concept The Purpose of lock mechanism in the SAP system is to synchronize the access to data on the database. Lock mechanism prevents two transactions from changing the same data on the database simultaneously. Lock Table The lock entries in the system need to be recorded. For this a table in the main memory of the enqueue server records the current locks in the system. For each elementary lock, the table specifies the owner, lock mode, name, and the fields in the locked table. Use The lock table is used to manage locks. Every time the enqueue server receives a lock request, the system checks the lock table to determine whether the request collides with an existing lock. If this is the case, the request is rejected. Otherwise, the new lock is written to the lock table.

Subsequent Analysis of Lock Table OverflowsThe maximum number of locks in the lock table is subject to an upper limit, which can be defined in a profile parameter. Parameter enque/table_size determines the size of the lock table in KB. You can determine both the maximum number and the current number of entries in the transaction using Extras/Statistics.

About Lock Table Overflow errorWe faced the error Lock Table Overflow during the BI content activation and when trying to collect large set of Objects to a Transport Request. This error resulted because of Overflow of Lock entries, as the number of Lock entries has exceed the upper limit of maximum locks specified in the Lock Table. Below are the error screen shots and suggestions from help for reference. Screen shot of error resulted when collecting the Objects.

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About Lock Entries and Lock Table Overflow

On going with Diagnosis we can find that the error is because of Overflowed table when the System tried to enter SAP Locks in the Lock Table.

Below is the Log screen shot and we can find the Lock Management error in After Import Method.

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About Lock Entries and Lock Table Overflow

We found the maximum number of Lock Entries recorded using SM12 -> Extras -> Statistics shows the statistics of the lock management, including the previous maximum fill levels (peak usage) of the partial tables in the lock table.

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About Lock Entries and Lock Table Overflow

From the Profile Parameter Attributes we can find the default values of Parameter enque/table_size.

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About Lock Entries and Lock Table Overflow

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About Lock Entries and Lock Table Overflow

Maintaining the Profile ParameterFrom the below steps you can have an idea of how we can find the Default values of Parameters.(For this we required the authorization to necessary set of Tcodes and Authorization Objects). The following table describes the main profile parameters associated with the lock mechanism. You can obtain a complete overview by searching for the parameters with the entry *enq* in transaction RZ11

Below is the screen shot of Enqueue Statistics with reflected limits allowing for more Lock Entries.

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About Lock Entries and Lock Table Overflow

On changing the parameter enque/table_size value with the help of BASIS we can increase the Lock Entries Limit. From the above screen shot we can find the maximum number of Lock Entries as 9085 while the earlier limit was 3603. Example: With the profile parameter "enque/table_size =32000, the size of lock table is set to 32000 KB (32 MB). With this setting, the tables can contain around 40000 entries. Note that the above sizes and numbers depend on various factors such as the kernel release, patch number, platform, address length (32/64-bit), and character width (Ascii/Unicode). Use the statistics display in SM12 to check the actual capacity of the lock table.

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About Lock Entries and Lock Table Overflow

Reason and Prerequisites for Lock Table OverflowA lock table overflow can occur if: Cause 1: The dimensions of the lock table are too small i.e. the lock table configured is too small. Cause 2: The update lags far behind or has shut down completely, so that the lock entries of the