IT33045: POSSIBLE DEADLATCH IN SQLOMEMINIT() WHEN IT LOADS CLIENT-SIDE LIBRARY

APAR status

• Closed as program error.

Error description

• Possible deadlatch in sqloMemInit() when it loads client-side
  library to execute trusted routine as shown in the following
  stack trace:
  
  Thread 197 (Thread 0x7f47473fe700 (LWP 21766)):
  #0  0x00007f4b8b84d53d in nanosleep () from
  /usr/lib64/libpthread.so.0
  #1  0x00007f4b7f262efc in ossLockGetConflict () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2osse.so.1
  #2  0x00007f47057fbf3d in sqloMemInit() () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #3  0x00007f47057fbe9f in sqloGetMemSet () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #4  0x00007f470579d672 in sqloopenp () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #5  0x00007f4705621fd8 in openLogFile(char*, PD_LOGFILE_HANDLE*,
  long*, int*, unsigned int*, char*, unsigned long,
  #6  0x00007f4705629084 in PDLogFacility::open
  #7  0x00007f470561c376 in pdLogInternal
  #8  0x00007f470561b67b in pdLog () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #9  0x00007f470633db40 in sqloGetEnvInternal () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #10 0x00007f470580d72c in sqlo_refresh_env () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #11 0x00007f470580e933 in sqloInstanceLocalDataPath () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #12 0x00007f470580e6d9 in sqloGetConfigPath () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #13 0x00007f470581f8b6 in EnvKeyName(char*, int, char const*,
  int)
  #14 0x00007f470581fdb3 in EnvPrfOpen(char const*, int,
  SEnvProfile**)
  #15 0x00007f470581ad39 in EnvRegGetProfile(SEnvRegistry*, char
  const*, int, SEnvProfile**)
  #16 0x00007f470633d6e2 in sqloGetEnvInternal () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #17 0x00007f47057f3722 in md_Initialize() () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #18 0x00007f47057fc14f in sqloimem() () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #19 0x00007f47057fbf1b in sqloMemInit() () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #20 0x00007f47057fd163 in sqlogmshr () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #21 0x00007f47057fcf0f in sqloGetPrivateSet () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #22 0x00007f47057fce8f in MemOssPool(SQLO_MEM_POOL**) () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #23 0x00007f47057f8ef0 in sqlogmblkEx () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #24 0x00007f47056c6e66 in
  sqleBeginTrustedCtxInternal(sql_app_ctx**, sql_static_data*)
  #25 0x00007f47056ffa25 in sqleUCtrustedRtnInit () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2.so.1
  #26 0x00007f4b82b92654 in sqleUCtrustedLvlInit(sql_static_data*,
  sqlrr_cb*, sqlri_ufob*)
  #27 0x00007f4b83d2612c in sqlriOneTimeInitRtn1Trusted(sqlrr_cb*,
  sqlri_ufob*, bool)
  #28 0x00007f4b83d24c63 in sqlriOneTimeInitRtn(sqlrr_cb*,
  sqlri_ufob*, bool)
  #29 0x00007f4b86a14466 in sqlriusf_common(sqlrr_cb*,
  sqlri_ufob*) () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2e.so.1
  #30 0x00007f4b8600c294 in sqlriusf(sqlrr_cb*) () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2e.so.1
  #31 0x00007f4b86a05df6 in sqlriSectInvoke(sqlrr_cb*,
  sqlri_opparm*)
  #32 0x00007f4b869e8f8a in
  sqlrr_process_execute_request(sqlrr_cb*, int, bool)
  #33 0x00007f4b869e635c in sqlrr_execute(db2UCinterface*,
  UCstpInfo*)
  #34 0x00007f4b86929936 in sqljs_ddm_excsqlstt(db2UCinterface*,
  sqljDDMObject*)
  #35 0x00007f4b86928ece in sqljsParseRdbAccessed(sqljsDrdaAsCb*,
  sqljDDMObject*, db2UCinterface*)
  #36 0x00007f4b82c5a1ec in sqljsParse(sqljsDrdaAsCb*,
  db2UCinterface*, sqeAgent*, bool)
  #37 0x00007f4b82c54779 in sqljsSqlam(db2UCinterface*, sqeAgent*,
  bool)
  #38 0x00007f4b82c52c8c in sqljsDriveRequests(sqeAgent*,
  db2UCconHandle*)
  #39 0x00007f4b82c4fce9 in
  sqljsDrdaAsInnerDriver(SQLCC_INITSTRUCT_T*, bool)
  #40 0x00007f4b82c4f8db in sqljsDrdaAsDriver(SQLCC_INITSTRUCT_T*)
  () from /home/appusers/db2m7r/sqllib/lib64/libdb2e.so.1
  #41 0x00007f4b82949a4f in sqeAgent::RunEDU() () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2e.so.1
  #42 0x00007f4b84188eb7 in sqzEDUObj::EDUDriver() () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2e.so.1
  #43 0x00007f4b8392fb93 in sqloEDUEntry () from
  /home/appusers/db2m7r/sqllib/lib64/libdb2e.so.1
  #44 0x00007f4b8b84574a in start_thread () from
  /usr/lib64/libpthread.so.0
  #45 0x00007f4b7e4d9f6d in clone () from /usr/lib64/libc.so.6
  
  The problem has only been observed in an environment were there
  had been issues accessing the db2 global registry
  (/var/db2/global.reg). I.e. it is unlikely to happen in a
  "healthy" environment.
  

Local fix

• Try to keep a "dummy" trusted routine opened in the instance, so
  the client side library will always be loaded in db2 (and never
  unloaded). For example have a db2 connection and issue something
  like this :
  
     db2 values dayofweek(current timestamp)
  
  and never let that go / keep it open for the lifetime of the
  database / instance (just need it for one database).
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 Version 11.1 Mod 4 Fix Pack 6.                *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 Version 11.1 Mod 4 Fix Pack 6.
  

Temporary fix

Comments

APAR Information

• 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

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels