PM81491: HUNG IN DSNTABA

A fix is available

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APAR status

  • Closed as program error.

Error description

  • If Lock Timeout happens, DSNTLSUS calls conversion process. When
    this processing is active, Cancel Thread may be issued. That
    will cause another lock request under the same agent structure,
    which opens the door to messing with the RLPFUSER and other
    fields used in SYNC processing which will make DSNTABA make the
    wrong decision.
    It causes thread is hung in DSNTABA,
    Also ABEND378 RC0000001C will occur if second Lock request will
    finish with a timeout because TRWA196 is already zero.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All DB2 users.                               *
    ****************************************************************
    * PROBLEM DESCRIPTION: There are 2 known symptoms:             *
    *                                                              *
    *                      1. A thread hung in CSECT DSNTABA.      *
    *                      2. ABEND378 RC0000001C RC1C as a        *
    *                         result of a call from CSECT          *
    *                         DSNTLSUS.                            *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    A thread involved in an IRLM timeout may require a UTF/EBCDIC
    conversion. Internal routine to preform such conversion may
    issue another IRLM call under the same DB2 agent structure.
    At this point there are 2 possible cases:
    
    1. If the subsequent request times out, it will incorrectly
    free internal agent storage and return.  The original IRLM
    request will attempt to free the same storage and result in
    ABEND378 RC0000001C RC1C.
    
    2. If the original request was cancelled while suspended in
    IRLM, but was already involved in partial timeout processing in
    IRLM before the cancel, the subsequent request will clear
    out an internal pointer upon its completion.  DB2 system agent
    uses this pointer during abort processing to see if SYNC should
    be preformed on the original IRLM request, and will inocrrectly
    issue the IRLM SYNC request. This will result in a hang of this
    system agent in CSECT DSNTABA
    

Problem conclusion

  • Change DB2 logic to avoid issuing a lock request during the
    UTF/EBCDIC conversion.
    

Temporary fix

  • *********
    * HIPER *
    *********
    

Comments

APAR Information

  • APAR number

    PM81491

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-01-27

  • Closed date

    2013-03-06

  • Last modified date

    2013-04-02

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

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

    UK92333 UK92334

Modules/Macros

  •    DSNTLSUS
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UK92333

       UP13/03/26 P F303

  • R910 PSY UK92334

       UP13/03/26 P F303

Fix is available

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Document information


More support for:

DB2 for z/OS

Software version:

A10

Reference #:

PM81491

Modified date:

2013-04-02

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