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IC70802: MEMORY LEAK IN DATABASE HEAP ON HADR STANDBY DATABASE EACH TIME A NEW LOG FILE IS CREATED.

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APAR status

  • Closed as program error.

Error description

  • A memory leak occurs in Database Heap on HADR standby database.
    This memory leak happens at a data structure used by log file
    management on standby database. This data structure is allocated
    when a new log file is created. But, it is not freed after
    using. Fortunately, this data structure will be reused if its
    corresponding log file is reused.
    
    So, this memory leak can be triggered by LOGARCHMETH1 =
    LOGRETAIN, since log files will not be reused.
    
    Database Heap memory usage can be monitored by one of the
    following methods:
    - db2pd -db <database> -mempools   (monitor the "dbh" pool)
    - database snapshot
    - select POOL_ID, POOL_CUR_SIZE, POOL_WATERMARK from
    sysibmadm.snapdb_memory_pool where POOL_ID = 'DATABASE'
    
    If this memory leak exists, you can observe a memory usage
    increase by 2096 bytes for every new log file. You can use db2pd
    to monitor memory usage of this data structure.
    
      db2pd -d <standby db name> -memb sort 2
    
    Here is a sample output:
    ========================
    Memory blocks sorted by size for dbh pool:
    PoolID   PoolName TotalSize(Bytes) TotalCount LOC File
    ......
    2        dbh      16768            8          74  418710486
    
    Please note that the file 418710486 is your target to monitor.
    "TotalCount" means how many data structures allocated, and still
    not released.
    "TotalSize(Bytes)" means how many bytes occupied by this data
    structure.
    You can see that "TotalSize(Bytes) / TotalCount = 2096" and both
    of them keep rising along with new log files being created.
    

Local fix

  • Set log archive method to other methods, instead of LOGRETAIN.
    Alternatively, if you have chance to restart your standby
    database, the memory will be freed.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL.                                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * A memory leak occurs in Database Heap on HADR                *
    * standbydatabase.This memory leak happens at a data structure *
    * used by logfile management on standby database. This data    *
    * structure isallocated when a new log file is created. But,   *
    * it is notfreed after using. Fortunately, this data structure *
    * will bereused if its corresponding log file is reused.So,    *
    * this memory leak can be triggered byLOGARCHMETH1=LOGRETAIN,  *
    * since log files will not be reused.Database Heap memory      *
    * usage can be monitored by one of thefollowing methods:-      *
    * db2pd -db <database> -mempools  (monitor the "dbh" pool)-    *
    * database snapshot- select POOL_ID, POOL_CUR_SIZE,            *
    * POOL_WATERMARK fromsysibmadm.snapdb_memory_pool where        *
    * POOL_ID = 'DATABASE'If this memory leak exists, you can      *
    * observe a memory usageincrease by 2096 bytes for every new   *
    * log file. You can usedb2pd to monitor memory usage of this   *
    * data structure.db2pd -d <standby db name> -memb sort 2Here   *
    * is a sample output:========================Memory blocks     *
    * sorted by size for dbh pool:PoolID  PoolName                 *
    * TotalSize(Bytes) TotalCount LOC File......2        dbh       *
    * 16768            8          74  418710486Please note that    *
    * the file 418710486 is your target tomonitor."TotalCount"     *
    * means how many data structures allocated, andstill not       *
    * released."TotalSize(Bytes)" means how many bytes occupied by *
    * thisdata structure.You can see that "TotalSize(Bytes) /      *
    * TotalCount = 2096" andboth of them keep rising along with    *
    * new log files beingcreated.                                  *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Update to v95fp7 or later.                                   *
    ****************************************************************
    

Problem conclusion

  • This problem is first fixed in version 9.5 fixpack 7.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC70802

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    950

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-08-26

  • Closed date

    2010-10-25

  • Last modified date

    2010-10-25

  • APAR is sysrouted FROM one or more of the following:

    IC70644

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R950 PSY

       UP

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Document Information

Modified date:
25 October 2010