IT08390: SERVER CRASHES USING ER, REFERENTIAL CONSTRAINTS, AND UPDATE STATISTICS

APAR status

• Closed as program error.

Error description

• Running a stress test using 3 tables with referential
  constraints between them, and having ER replicates defined on
  them, and then a constant stress of update statistics commands
  being run, causes the server to assert fail in various ways.
  
  The 1 thing that appears to be in common between all the crashes
  is that it appears the server is referencing a freed data
  dictionary entry.
  
  The stress test was also run with CCFLAGS set to 0x08000200
  (which enables memory scribbling and any dictionary entry that
  goes to refcount of 0 to be automatically freed).
  
  Here's the kinds of af's seen:
  
  1) negative memory size allocation
  12:09:35  Assert Failed: Condition Failed (Bad allocation size
  (-515) for pool 'CDR' (0x47cd7040)), In (mt_shm_malloc_segid)
  12:09:35   Who: Session(82606, informix@server, 0, 0x46ac3b30)
          Thread(82639, CDRD_55, 46a84fa8, 1)
  
  afstack
  afhandler
  affail_interface
  mem_asfail
  mt_shm_malloc_segid
  mt_realloc
  cdrMemReallocRtn
  dsiGetReplRow
  dsiResolverThread
  cdrTrampolineThread
  th_init_initgls
  startup
  
  -515 as a hex number is (in 2 bytes form or a short) is 0xfdfd
  which is the byte pattern of freed memory (the free scribble
  byte is 0xfd)
  
  2) segv with this stack:
  
  afstack
  mt_ex_throw_sig
  afsig_handler
  <signal frame>
  cmprstr
  gettab
  sqcdrDbop
  dsiResolverThread
  cdrTrampolineThread
  th_init_initgls
  startup
  
  3) af warning about dictionary entry not found with either of
  these 2 stacks (with the decrrefcount 1 happening more
  frequently)
  
  afwarn_interface
  decrrefcount
  rmdiclink
  closerel
  close_cb_subtree_r
  close_cb_subtree
  closesdb
  doreleasesdb
  sqcdrDbop
  dsiResolverThread
  cdrTrampolineThread
  th_init_initgls
  startup
  
  
  afwarn_interface
   incrrefcount
  make_constr_tab_hierarchy
  set_per_constr_tabs
  bldrefsx
  maybe_bldrefs
  sqbind
  sq_common_bind
  sqmain
  spawn_thread
  th_init_initgls
  startup
  
  and a couple other far less frequently occuring segv crashes.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * those using referential constraints                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IBM Informix Server 12.10.xC6                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IBM Informix Server 12.10.xC6
  

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 PSN

     UP

• RB70 PSY

     UP

• RC10 PSN

     UP

• RC10 PSY

     UP