IT22284: APPLICATION HEAP CAN BE EXHAUSTED BY REBAL FUNCTION AND THIS CANLEAD TO APPLICATION FAILURE WITH OUT OF MEMORY

Db2 Version 11.1 Mod 3 Fix Pack 3 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod3 Fix Pack3 iFix001 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod3 Fix Pack3 iFix002 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 5 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 7 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• On a database running with INTRA_PARALLEL=YES and DEGREE higher
  than 1, if application is failing with out of memory and
  following
  command
  
  db2pd -alldbs -memblocks appl | grep -A 10  "All memory cons"
  
  shows that one allocation is taking entire application heap:
  
  
  All memory consumers in Application memory set:
  PoolAddr           PoolID     PoolName   SecondID
  TotalSize(Bytes)     %Bytes TotalCount %Count LOC   File
  0x00007FEAEB958CE8 1          apph       15638     7619892696
  89.43  879489     0.29   1102  1984253944
  
  where 7619892696 is the size of entire application heap.
  
  Plan that is taking all this memory has REBAL operator and above
  allocation is coming from REBAL code.
  This fix is needed to control memory consumed by REBAL
  

Local fix

• db2set DB2_COMPILER_SMP_OVERRIDES=1 (requires instance recycle)
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 version 111m3fp3                              *
  ****************************************************************
  

Problem conclusion

• APPLICATION HEAP CAN BE EXHAUSTED BY REBAL FUNCTION AND THIS CAN
  LEAD TO APPLICATION FAILURE WITH OUT OF MEMORY
  

Temporary fix

• see Local 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

• RB10 PSN

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