IT11952: MEMORY CORRUPTION AND OTHER ERRORS POSSIBLE WHEN USING CDC

APAR status

• Closed as program error.

Error description

• When using the Change Data Capture API for Informix Dynamic
  Server a possibility exists for memory corruption to occur under
  certain circumstances. This is a regression that is due to the
  fix for APAR IT07378. When the corruption occurs a number of
  messages will appear in the online log together with an Assert
  Failure for memory block header corruption. The online log
  messages are of the form:
  15:31:42  CDR: A magic number verify failed for Snoop class
  SnoopBuf_t File snoop/snoopxformbaseclass.c Line 311 at address
  700003176e73140
    actual magic value was 0xe000062
  15:31:42  CDR: A magic number verify failed for Snoop class
  SnoopBuf_t File snoop/snoopobjs.c Line 6922 at address
  700003176e73140
    actual magic value was 0xe000062
  ...
  15:31:42  CDC: Log Seq:  Page out-of-seq error [got page
  769640:7d4f, cur page 769640:7d49]
  15:31:42  CDC: Log Seq:  Page out-of-seq error [got page
  769640:7d50, cur page 769640:7d49]
  ...
  15:31:42  Assert Failed: Memory block header corruption detected
  in mt_shm_free 2
  An example stack for the failing thread in the AF file is:
  (oninit)afstack
  (oninit)afhandler
  (oninit)affail_interface
  (oninit)mt_free
  (oninit)snoopsess_friend_freer_callback
  (oninit)sbt_subclass_fmrowmig_p_deinit
  (oninit)sbt_subclass_fmrowmig_deactivate_begin
  (oninit)sbt_deactivate_begin
  (oninit)sbtm_p_deactivate_core
  (oninit)sbtm_deactivate
  (oninit)snoopsess_p_deactivate_core
  (oninit)snoopsess_deactivate
  (oninit)cdc_apiudr_deactivatesess
  (oninit)udrlm_clang_execute_internal
  (oninit)udrlm_clang_execute
  (oninit)udrlm_exec_routine
  (oninit)udr_execute
  (oninit)exroutine
  (oninit)geval
  (oninit)evalcols
  (oninit)runudr
  (oninit)ip_curnext
  (oninit)ip_fetch
  (oninit)getrow
  (oninit)fetchrow
  (oninit)exfetch
  (oninit)sql_nfetch
  (oninit)sq_nfetch
  (oninit)sqmain
  (oninit)listen_verify
  (oninit)spawn_thread
  (oninit)th_init_initgls
  (oninit)startup
  Due to the nature of memory block header AFs there could be
  other possible stacks.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of the Change Capture API (CDC)                        *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IBM Informix Server 11.70.xC9                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IBM Informix Server 11.70.xC9
  

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

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels

• RB70 PSY

     UP

• RC10 PSY

     UP