IBM Support

IT35039: EXCEPTION CAUGHT DURING QUERY OF SYSSCBLST TABLE MAY LEAVE MUTEXLOCKED WITH POTENTIAL FOR DEADLOCK

Subscribe to this APAR

By subscribing, you receive periodic emails alerting you to the status of the APAR, along with a link to the fix after it becomes available. You can track this item individually or track all items by product.

Notify me when this APAR changes.

Notify me when an APAR for this component changes.

 

APAR status

  • Closed as program error.

Error description

  • The processing of a query for the pseudo table sysscblst in the
    sysmaster database may result in an exception which interrupts
    the query processing. The clean up of the query processing may
    leave a mutex named scbthd in a locked state which can later
    lead to a deadlock situation. The deadlock can be seen in the
    output of the "onstat -g wmx" command as in this example:
    
    Mutexes with waiters:
    mid      addr             name               holder   lkcnt
    waiter   waittime
    19       443a3838         session            19099537 0      20
    1729
    
    19099536 1729
    718290922 21044fca0        scbthd             19099536 0
    19094197 1729
    
    19099537 1729
    
    The thread with id 19099537 is the holder of the session mutex
    and is waiting for access to the scbthd mutex. The thread
    holding that mutex, with id 19099536, is waiting for the session
    mutex and the result is deadlock. A typical stack for the thread
    holding the session mutex may be:
    
    yield_processor_mvp
    mt_lock_wait
    mt_lock_helper
    mt_prscblst
    pstread
    pst_rsread
    rsread
    fmread
    readseq_single
    gettupl
    scan_next
    hjoin_next
    hjoin_next
    sort_open
    prepselect
    open_cursor
    sql_open
    sq_open
    sqmain
    
    An example stack for the thread holding the scbthd mutex may be:
    
    yield_processor_mvp
    mt_lock_wait
    mt_lock_helper
    destroy_session
    sq_exit
    sqmain
    
    Other stacks for this thread may be possible.
    
    Queries using the sysmaster view syssessions are also
    susceptible.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users of Informix Server prior to 12.10.xC15 and 14.10.xC6.  *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Informix Server 12.10.xC15 (when available) or    *
    * 14.10.xC6 (when available).                                  *
    ****************************************************************
    

Problem conclusion

  • Fixed in Informix Server 12.10.xC15 and 14.10.xC6.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT35039

  • Reported component name

    INFORMIX SERVER

  • Reported component ID

    5725A3900

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2020-11-24

  • Closed date

    2020-12-10

  • Last modified date

    2020-12-10

  • 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

    INFORMIX SERVER

  • Fixed component ID

    5725A3900

Applicable component levels

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU029","label":"Software"},"Product":{"code":"SSGU8G","label":"Informix Servers"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"C10"}]

Document Information

Modified date:
11 December 2020