DB2 FOR LUW / DB2FORLUW / A50 - DB2

Deadlatch can be observed between
SQLO_LT_sqeApplication__masterAppLatch and
SQLO_LT_SQLP_TENTRY__tranEntryLatch which may lead to a hang
situation where connections may hang as well till a recycle is
performed.

Diagnostics:

db2pd -latches will show the deadlatch


0x00007FFF01A00B80 24770      25979      Unknown
742        SQLO_LT_SQLP_TENTRY__tranEntryLatch 1
25979 was waiting for 24770

0x00007FFC507E21C4 25979      24770      Unknown
313        SQLO_LT_sqeApplication__masterAppLatch 1
24770 is waiting for 2579

Below are the callstacks for the dead latch situation:


Callstack for the waiter on the masterAppLatch:

    ossDumpStackTraceEx
    OSSTrapFile::dumpEx
    sqlo_trce
    sqloDumpDiagInfoHandler
    sqloSpinLockConflict
    sqeApplication::lockApplication
    sqlkdDispatchRequest
    sqlkdInterrupt
    sqlrr2pd
    sqlrkprp
    sqlrr_xprepare
    sqljsSyncPrepare
    sqljs_ddm_syncctl
    sqljsParseRdbAccessed
    sqljsParse

LatchInformation>
Waiting on latch type: (SQLO_LT_sqeApplication__masterAppLatch)
- Address: (0x7ffc507e21c4), Line: 2665, File: sqlkdsnd.C
Holding Latch type: (SQLO_LT_SQLP_TENTRY__tranEntryLatch) -
Address: (0x7fff01a00b80), Line: 742, File:
/view/db2_v97fp11_linuxamd64_s150922/vbs/engn/include/sqlpi_inli
nes.h HoldCount: 1


Callstack for the holder of masterAppLatch and waiter on
tranEntryLatch:

    ossDumpStackTraceEx
    OSSTrapFile::dumpEx
    sqlo_trce
    sqloDumpDiagInfoHandler
    sqloSpinLockConflict
    sqlpm_write_appl_locks
    sqm_snap_appl_locks
    address: 0x00007FFFF4325A13 ; dladdress:
    ; offset in lib: 0x0000000001F20A13 ;
    address: 0x00007FFFF432982B ; dladdress:
    ; offset in lib: 0x0000000001F2482B ;
    sqlmonssagnt

LatchInformation>

Waiting on latch type: (SQLO_LT_SQLP_TENTRY__tranEntryLatch) -
Address: (0x7fff01a00b80), Line: 742, File:
/view/db2_v97fp11_linuxamd64_s150922/vbs/engn/include/sqlpi_inli
nes.h

Holding Latch type: (SQLO_LT_sqeLocalDatabase__dblatch) -
Address: (0x2007585e8), Line: 413, File: sqlmutil.C HoldCount: 1
Holding Latch type: (SQLO_LT_sqeAppServices__m_appServLatch) -
Address: (0x2002f04f8), Line: 8002, File: sqlmonss.C HoldCount:
1
Holding Latch type: (SQLO_LT_sqeApplication__masterAppLatch) -
Address: (0x7ffc507e21c4), Line: 313, File:
../include/sqle_app_services.h HoldCount: 1
Holding Latch type:
(SQLO_LT_SQLP_TENTRY__snapshotProcessingLatch) - Address:
(0x7fff01a00b90), Line: 1236, File: sqlplkss.


Levels affected:
V9.7 FP11 and above

INTERNAL:
This caused by IT09943

****************************************************************
* USERS AFFECTED:                                              *
* ALL                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to DB2 Version 10.5 and Fix Pack 8                   *
****************************************************************

not known / see Local fix

forerunner  : IT12866 
follow-up : 

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

17.05.2017
17.05.2017
17.05.2017