DB2 V10.5 FP4上严重的APAR IT04326

IT04326: PACKAGE CACHE MEMORY USE CAN EXCEED CONFIGURED SIZE RESULTING IN MEMORY EXHAUSTION ON DB2 Cancun Release 10.5.0.4.


Error description

    This package cache memory problem is specific to DB2 Cancun
    Release 10.5.0.4 (also known as Fix Pack 4).

    When the size of the package cache reaches its configured limit
    and new entries in the package cache are needed, DB2 will evict
    older entries in order to maintain the size at the configured
    limit. With this APAR, under certain timing conditions, if the
    size limit is reached, rather than evicting older entries, the
    package cache may exceed its configured limit and continue to
    grow.  This can result in the package cache unexpectedly
    consuming additional database memory or instance memory.

    This condition can be detected by issuing:

    db2pd -db <dbname> -mempools

    and determining if the logical size of package cache heap
    significantly exceeds the configured size.  In the output of
    this command, the logical size is indicated by the LogSz column,
    and the configured size is indicated by the CfgSize column. The
    package cache is identified by the PoolName 'pckcacheh'.

    An example output of this command is:

    Memory Pools:
    Address            MemSet   PoolName   Id    SecondId   Overhead
    LogSz       LogHWM      PhySz       PhyHWM     CfgSize    Bnd
    BlkCnt CfgParm
    0x0000005AA9F520E8 CBLU5    pckcacheh  7     0           2929472
    1363319099  1466382434  1569652736  1597964288  1769472     No
    575359 PCKCACHESZ


    In this example, the package cache has a configured size of
    1769472 bytes but a larger logical size of 1363319099 bytes,
    thus an indication of the APAR.

Local fix

    Executing the FLUSH PACKAGE CACHE DYNAMIC statement will remove
    unused dynamic SQL from the cache, thereby freeing up space. If
    the workload is predominantly dynamic SQL, then periodically
    issuing FLUSH PACKAGE CACHE can effectively provide relief by
    keeping the size of the package cache below the configured
    limit.

    A special build  (packaged as universal fix pack image) with the
    fix for this APAR (based on DB2 Cancun Release 10.5.0.4) is
    available for download from Fix Central at the following
    location:
    http://www.ibm.com/support/fixcentral/swg/quickorder?parent=ibm%
    7EInformation%2BManagement&product=ibm/Information+Management/DB
    2&release=10.5.*&platform=All&function=aparId&apars=IT04326&sour
    ce=fc


Problem conclusion

    Fixed in DB2 for LUW version 10.5.5.

    A special build  (packaged as universal fix pack image) with the
    fix for this APAR (based on DB2 Cancun Release 10.5.0.4 (also
    known as Fix Pack 4) ) is available for download from Fix
    Central at the following location:
    http://www.ibm.com/support/fixcentral/swg/quickorder?parent=ibm%
    7EInformation%2BManagement&product=ibm/Information+Management/DB
    2&release=10.5.*&platform=All&function=aparId&apars=IT04326&sour
    ce=fc