PH63808: DB2 DEADLOCK BETWEEN INDEX TREE LOTCH AND GBP CONVERSION LOCK AMONG MEMBERS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• It is a timing window causing deadlock when header page is
  updated during index insert and pageset plock negotiation is
  triggered to downgrade lock from X to SIX.
  Because index lotch is involved, it is not a deadlock that can
  be detected and broken by IRLM.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Db2 12 for z/OS and Db2 13 for z/OS      *
  *                 data sharing users using indexes             *
  ****************************************************************
  * PROBLEM DESCRIPTION: Message IXL045E was issued when a       *
  *                      thread inserting into an index,         *
  *                      which needed to update the index        *
  *                      header page, deadlocked with            *
  *                      another thread in a different Db2       *
  *                      member.                                 *
  ****************************************************************
  * RECOMMENDATION: Apply corrective PTF when available          *
  ****************************************************************
  In a Db2 data sharing system, a thread
  inserting into an index needed to update
  the index header page and directory page.
  This thread held the index tree lotch and
  issued the page set write request on
  the index page set. The page set write
  request waited for the group buffer pool
  (GBP) conversion lock.
  
  Meanwhile, another Db2 member held the
  GBP conversion lock and requested the
  IS page set P-lock. The P-lock exit on
  the first Db2 member waited for the
  index tree lotch, which caused a
  deadlock situation between the two
  Db2 members. MSGIXL045E was issued as
  a result of the deadlock situation.
  

Problem conclusion

• The Db2 code has been updated to avoid
  requesting the index tree lotch before
  the first page set write is acquired for
  an index on a Db2 member.
  

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:

  UI99551 UI99552

Modules/Macros

• DSNKDLE  DSNKINSL
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI99551

     UP25/01/08 P F501

• RD10 PSY UI99552

     UP25/01/08 P F501

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.