DB2 FOR LUW / DB2FORLUW / 910 - DB2

Application shared memory (appshrh) might leak when inserting 
rows to MDC tables. 
 
This symptom could be perceived by virtue of "db2pd -db 
<db_name> -memblocks top".  The memblock will increase %Bytes 
and/or %Count even after the insert commits or the application 
terminates. 
 
1st Round: 
Top memory consumers in AppCtl memory set: 
PoolID    PoolName  TotalSize(Bytes)    %Bytes TotalCount 
%Count LOC  File 
20        appshrh   100904064            93.40 788313 
72.06  3450 1560397958 
 
2nd Round: 
Top memory consumers in AppCtl memory set: 
PoolID    PoolName  TotalSize(Bytes)    %Bytes TotalCount 
%Count LOC  File 
20        appshrh   143394048            95.33 1120266 
79.21  3450 1560397958 
 
3rd Round: 
Top memory consumers in AppCtl memory set: 
PoolID    PoolName  TotalSize(Bytes)    %Bytes TotalCount 
%Count LOC  File 
20        appshrh   479587200           98.43  3746775 
92.31  3450 1560397958 
 
When an insert into an MDC table occurs, the composite block 
index is probed for the logical cell corresponding to the 
dimension values of the record to be inserted.  To improve the 
performance of a transaction inserting multiple rows into an 
MDC, a cache of cell values is maintained to quickly find the 
target cell for the next insert without having to probe the 
composite block index. 
 
The allocated memory should be freed at the end of a transaction 
or when an application terminates. But there is a problem where 
DB2 does not free the entire list.

**************************************************************** 
* USERS AFFECTED:                                              * 
* All users                                                    * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* Application shared memory (appshrh) might leak when          * 
* inserting rows to MDC tables.                                * 
*                                                              * 
* This symptom could be perceived by virtue of "db2pd -db      * 
* <db_name> -memblocks top".  The memblock will increase       * 
* %Bytes and/or %Count even after the insert commits or the    * 
* application terminates.                                      * 
*                                                              * 
* 1st Round:                                                   * 
* Top memory consumers in AppCtl memory set:                   * 
* PoolID    PoolName  TotalSize(Bytes)    %Bytes TotalCount    * 
* %Count LOC  File                                             * 
* 20        appshrh   100904064            93.40 788313        * 
* 72.06  3450 1560397958                                       * 
*                                                              * 
* 2nd Round:                                                   * 
* Top memory consumers in AppCtl memory set:                   * 
* PoolID    PoolName  TotalSize(Bytes)    %Bytes TotalCount    * 
* %Count LOC  File                                             * 
* 20        appshrh   143394048            95.33 1120266       * 
* 79.21  3450 1560397958                                       * 
*                                                              * 
* 3rd Round:                                                   * 
* Top memory consumers in AppCtl memory set:                   * 
* PoolID    PoolName  TotalSize(Bytes)    %Bytes TotalCount    * 
* %Count LOC  File                                             * 
* 20        appshrh   479587200           98.43  3746775       * 
* 92.31  3450 1560397958                                       * 
*                                                              * 
* When an insert into an MDC table occurs, the composite block * 
* index is probed for the logical cell corresponding to the    * 
* dimension values of the record to be inserted.  To improve   * 
* the performance of a transaction inserting multiple rows     * 
* into an MDC, a cache of cell values is maintained to quickly * 
* find the target cell for the next insert without having to   * 
* probe the composite block index.                             * 
*                                                              * 
* The allocated memory should be freed at the end of a         * 
* transaction or when an application terminates. But there is  * 
* a problem where DB2 does not free the entire list.           * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 9.1.0.11.                                     * 
****************************************************************

Restart the database to free the leaked memory in appshrh.

DB2 Version 9.1 Fix Pack 11  for Linux, UNIX and Windows
 DB2 Version 9.1 Fix Pack 12  for Linux, UNIX and Windows
 

The problem is fixed in DB2 9.1.0.11.

Restart the database to free the leaked memory in appshrh.

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

06.07.2011
07.12.2011
07.12.2011

9.1.0.11