PM80045: 2 THREADS HUNG AFTER ONE WAS CANCELLED ABENDS33E WHILE I/O IN PROGRESS RESULTING IN A DEADLOCK SITUATION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• 2 threads were hung after one of them was cancelled while I/O
  in progress. And the other one was executing expand process.
  The cancelled thread was waiting for a service of open/close
  service task.
  The open/close service task was executing a request from the
  thread which was executing expand process. And it was waiting
  for the completion of the cancelled I/O.
  It caused deadlock.
  .
  Cancelled thread
  The request was queued to the open/close service task
  EU switch B247CA7A DSNB1IOR UK76848 +19DA
  EU switch B247CA7A DSNRUA01 UK28121 +0AA2
  .
  The thread using the open/close service task
  Suspended B753BEE8 DSNB1OST UK76441 +23A8
  EU switch B247CA7A DSNB1OPP UK77964 +2CAC
  Suspended B248A9A4 DSNVDISC UK56258 +0D2C
  This thread was cancelled and waiting for the completion of the
  expand service task.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 users.                               *
  ****************************************************************
  * PROBLEM DESCRIPTION: When a thread is cancelled during I/O   *
  *                      processing and a concurrent thread is   *
  *                      adding new volumes to extend a data set *
  *                      that the cancelled thread uses, these   *
  *                      two threads may run into a service task *
  *                      deadlock.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  An agent is driving a data set to be extended to an additional
  volume, and at the same time another agent is cancelled while
  performing an I/O to the same data set.  The cancelled thread
  waits for the Open/Close service task to become available to do
  I/O recovery while the other thread executes the same service
  task and deadlocks with the cancelled thread as it waits for I/O
  recovery to complete.
  

Problem conclusion

• DB2 has been fixed to execute a new service task as part of the
  I/O recovery and avoid the conflict of using the same Open/Close
  service task between I/O recovery and data set extend
  processing.
  

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:

  UK91782 UK91783

Modules/Macros

•    DSNB1IOR
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK91782

     UP13/03/05 P F303

• R910 PSY UK91783

     UP13/03/05 P F303

Fix is available

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