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IC75260: HANG with DB2EVMTI DEADLATCH ON SQLO_LT_SQM_EVMON_MGR__EM_LIST_LATCH

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • This APAR describes a deadlatch situation with the deadlock
    event monitor (DB2EVMTI).
    
    1) DB2EVMTI is trying to log deadlock events to its target
    tables and finds that the tables are already locked.
    2) This lock situation triggers another deadlock and the
    deadlock event monitor while trying to generate the new deadlock
    event enters into a deadlatch situation with the deadlock
    detector (DB2DLOCK).
    
    The latch that is been waited on is
    SQLO_LT_SQM_EVMON_MGR__EM_LIST_LATCH. As the db2evmti is holding
    also SQLO_LT_sqeLocalDatabase__dblatch, new connections will be
    not possible and we will have the system hung.
    
    Stack for db2evmti
    
    00002B7C23CA4F7F ossDumpStackTraceEx + 0x01f7
      00002B7C23CA0ABA _ZN11OSSTrapFile6dumpExEmiP7siginfoPvm +
    0x00b4
      00002B7C23CA0B81 _ZN11OSSTrapFile4dumpEmiP7siginfoPv + 0x0009
      00002B7C20216103 sqlo_trce + 0x03f3
      00002B7C2025650F sqloDumpDiagInfoHandler + 0x00dd
      000000364280EB10 __invoke_dynamic_linker__ + 0x1280
      00000036420BAA27 __sched_yield + 0x0007
      00002B7C1EFA5A3D sqloSpinLockConflict + 0x015d
      00002B7C20DDC701 _Z12sqlxp_errmsgP8sqlxp_cbhhijP5Token +
    0x000b
      00002B7C1F93E0BF
    _ZN13sqm_evmon_mgr17gen_en_dlock_connEP14sqeApplicationPPc +
    0x008b
      00002B7C1F928030
    _ZN15sqm_dlconn_list17gen_dlconn_eventsEPK8sqeAgentP8SQLP_LRB +
    0x0812
      00002B7C1F0086D2
    _Z8sqlplfndP8sqeAgentP14SQLP_LOCK_INFOP8SQLP_LCBP9SQLP_LHSHP15SQ
    LP_LTRN_CHAINP8SQLP_LRBSA_SA_P8SQLP_AWBbb
    + 0x0a02
      00002B7C20DF7491 _Z7sqlplrqP8sqeAgentP14SQLP_LOCK_INFO +
    0x1c71
      00002B7C20DB5366
    _Z13sqldLockTableP8sqeAgentP14SQLP_LOCK_INFOjti + 0x00d2
      00002B7C1ECB342A
    _Z24sqldGetTableCacheAndLockP8sqeAgentiitiiimiP14SQLP_LOCK_INFOP
    P16SQLD_TABLE_CACHE
    + 0x01e4
      00002B7C1EC9060E
    _Z13sqldRowInsertP8sqeAgenttthmiPP10SQLD_VALUEP13SQLD_TDATARECP8
    SQLZ_RID
    + 0x031c
      00002B7C1F0CB965
    _Z8sqlrinsrP8sqlrr_cbttitPP10SQLD_VALUEmP8SQLZ_RID + 0x0069
      00002B7C1F93344F _ZN17sqm_evmon_ttarget10write_dataEPcjh +
    0x190d
      00002B7C1F93AD2E
    _ZN14sqmEvmonBuffer10write_dataEP16sqm_evmon_target + 0x00e4
      00002B7C1EDDD76F _ZN14sqmEvmonWriter11evmonWriterEv + 0x061b
      00002B7C1ECD47C0 _Z26sqleIndCoordProcessRequestP8sqeAgent +
    0x00e8
      00002B7C1ECE1F5F _ZN8sqeAgent6RunEDUEv + 0x04c9
      00002B7C1F1E6BF1 _ZN9sqzEDUObj9EDUDriverEv + 0x006d
      00002B7C1F1E6B81 _Z10sqlzRunEDUPcj + 0x0009
      00002B7C1EFD0C9A sqloEDUEntry + 0x02ea
      000000364280673D pthread_cond_wait@@GLIBC_2.3.2 + 0x020d
      00000036420D3D1D clone + 0x006d
    
    Waiting on latch type: (SQLO_LT_sqm_evmon_mgr__em_list_latch) -
    Address: (0x20069dcd0), Line: 630, File: sqlmemgr.C
    
    Stack for db2dlock
    
    00002B7C23CA4F7F ossDumpStackTraceEx + 0x01f7
    00002B7C23CA0ABA _ZN11OSSTrapFile6dumpExEmiP7siginfoPvm + 0x00b4
    00002B7C23CA0B81 _ZN11OSSTrapFile4dumpEmiP7siginfoPv + 0x0009
    00002B7C20216103 sqlo_trce + 0x03f3
    00002B7C2025650F sqloDumpDiagInfoHandler + 0x00dd
    000000364280EB10 address: 0x000000364280EB10 ; dladdress:
    0x0000003642800000 ; offset in lib: 0x000000000000EB10 ;
    00000036420D517A semtimedop + 0x000a
    00002B7C1EF89EE5 sqloWaitEDUWaitPost + 0x01ad
    00002B7C1F93A59A _ZN17sqm_evmon_ostream10write_dataEPKcjb +
    0x01ce
    00002B7C1F9396C6 _ZN14sqmEvmonWriter10sendStreamEPPvbS0_ +
    0x054a
    00002B7C1F942FA6
    _ZN13sqm_evmon_mgr9sendEventEPPcP17sqm_evmon_id_list + 0x00c2
    00002B7C1F93DFDB _ZN13sqm_evmon_mgr13gen_dlock_evtEPPc + 0x00d1
    00002B7C20262F9C
    _Z29sqlplReportLocalDeadlockEventP8SQLP_LCBjjP9SQLP_LHSH +
    0x05ae
    00002B7C20261D66
    _Z17sqlpKillIfWaitingP9SQLP_DBCBP8SQLP_LCBjiiiPiP12sqm_dlock_idi
    jii
    + 0x0918
    
    Holding Latch type: (SQLO_LT_sqm_evmon_mgr__em_list_latch) -
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * This APAR will collect diagnostic info regarding the         *
    * deadlock                                                     *
    * participants in a similar scenario. In a deadlock scenario   *
    * if                                                           *
    * one of the participants is the deadlock event monitor        *
    * itself,                                                      *
    * DB2 will rollback the thread without collecting any          *
    * information in the event monitor tables, but the db2diag.log *
    * will have information about the event.The information that   *
    * is logged when an event monitor is involved as one of the    *
    * participants in a deadlock is:"The deadlock detector has     *
    * detected a deadlock with an EventMonitor agent as a          *
    * participant. Information about this event will not be sent   *
    * to                                                           *
    * the Event Monitor. Some details are provided below"These     *
    * messages are being logged at WARNING level indb2diag.log and *
    * will be followed by information on the holder and waiter of  *
    * the lock for deadlocks in which event monitor is found as    *
    * one                                                          *
    * of the participants.                                         *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 Version 9.7 and Fix Pack 5                    *
    ****************************************************************
    

Problem conclusion

  • Problem was first fixed in DB2 Version 9.7 and Fick Pack 5
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC75260

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-03-24

  • Closed date

    2011-12-09

  • Last modified date

    2011-12-09

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

    IC74510

  • 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

  • R970 PSY

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IC75260

Modified date: 09 December 2011