IBM Support

IC90645: CONTENTION ON SHARED MEMORY MUTEX SH_LOCK POSSIBLE WHEN MANY SESSIONS DISCONNECT SIMULTANEOUSLY AND VP PRIVATE CACHE IS FULL

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APAR status

  • Closed as program error.

Error description

  • When a large number of sessions, such as several hundred or
    more, disconnect simultaneously the memory associated with these
    sessions will be released. If the VP private memory cache is in
    use then such memory will normally be released to the cache.
    However if the sessions are using large amounts of memory then
    the VP cache may fill and memory blocks will then be released
    back to the virtual memory segment. This action will require the
    shared memory mutex "sh_lock" to be acquired whilst the released
    blocks are added into the segment and if there are many CPU VPs
    all attempting to do this operation at the same time then they
    will be forced to spin and wait to acquire the mutex.
    
    The command "onstat -g vpcache" may be used to help determine
    when this problem occurs by observing an increase in the count
    of blocks shown in the "drain" column. Increasing the size of
    the VP private cache by changing the value of the onconfig
    parameter VP_MEMORY_CACHE_KB may help to alleviate this issue.
    
    An example thread stack that may be seen when the problem
    occurs:
    
    mt_spin_lock_wait
    freeblks
    mt_free
    old_do_rhpfree
    relsdbmem
    doreleasesdb
    sqscb_cleanup
    destroy_session
    sqmain
    listen_verify
    spawn_thread
    startup
    
    Note that other function names may be seen in the middle of
    stack in place of doreleasesdb, relsdbmem etc.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All Users                                                    *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Update to IDS-11.70.xC8                                      *
    ****************************************************************
    

Problem conclusion

  • Problem Fixed In IDS-11.70.xC8
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC90645

  • Reported component name

    IBM IDS ENTRP E

  • Reported component ID

    5724L2304

  • Reported release

    B15

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-03-05

  • Closed date

    2014-02-26

  • Last modified date

    2014-02-26

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

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

Fix information

  • Fixed component name

    IBM IDS ENTRP E

  • Fixed component ID

    5724L2304

Applicable component levels

  • RB15 PSN

       UP

  • RB15 PSY

       UP

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Document Information

Modified date:
26 February 2014