PI58324: FAILURE TO FREE SOCKSEND LOCK LEADS TO MULTIPLE ASOB ABENDS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Within an outbound connection pooling environment, a task
  sitting in SOCKET SEND suspend is attempted to be terminated
  via a KILL command.
  
  ABEND AKKA is issued due to the KILL command and Message
  DFHSO0001 is attempted to be issued but is suppressed by the
  KILL processing. The log shows:
  
  DFHME0139 Message DFHSO0001 has been suppressed by KILL
  processing.
  
  This is followed by message:
  
  DFHSO0002 A severe error (code X'029F') has occurred in module
  DFHSOCK.
  
  This first DFHSO0002 dump shows the SOCKSEND lock was freed
  during the Functional Recovery routine of DFHSOS06, however the
  in_send flag was left on. Normal error processing continues
  then eventually DFHWBCL places the socket back into the pool
  for later use. The application carries on normally but is not
  actually killed.
  
  The application then issues another INVOKE SERVICE command and
  the same socket gets allocated from the pool. When processing
  gets to DFHSOS06 again, the SOCKSEND lock is acquired but the
  in_send flag is found to be on so the send function returns an
  exception and critically fails to release the lock. The socket
  gets put back into the pool for reuse again.
  
  The application again isues another INVOKE SERVICE command and
  the same socket gets allocated from the pool. Now when
  processing gets to DFHSOS06 the attempt to get the SOCKSEND
  lock fails with DUPLICATE_LOCK_OWNER and an ASOB abend is
  issued, causing the task to end.
  
  Now the KE_NUM slot that was being used also has inherited to
  SOCKSEND lock. This leads to multiple ASOB abends anytime a
  task is assigned this KE_NUM slot and requests the SOCKSEND
  lock.
  
  This can also eventually lead to a deadlock scneario between
  the SOCKSEND and SOMGLOCK.
  
  NOTE: This problem is only possible with outbound connection
  pooling being used in conjunction with a KILL command being
  issued during SOCKET SEND suspend.
  
  Additional Symptom(s) Search Keyword(s): KIXREVDWZ
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend ASOB at offset X'173C' in         *
  *                      DFHSOS06.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  CICS is being used as a web service requester with outbound
  HTTP connection pooling in effect.  A transaction issues an
  INVOKE SERVICE command using SSL to a server that becomes
  unresponsive.  This causes the socket send to wait and
  eventually time out.
  In the reporting customers case, CEKL SET TASK FORCEPURGE and
  CEKL SET TASK KILL were issued against the task.  This causes
  the DFHSOS06 recovery routine to be driven.  This releases the
  SOCKSEND lock, but does not turn off the socket's in_send flag.
  DFHSOCK reports an INTERNAL_LOGIC_ERROR and returns a disaster
  response, but the task continues.  However, as the socket's
  in_send bit is left on, subsequent sends fail with a
  SOCKET_IN_USE exception, and does not release the SOCKSEND
  lock.  The INVOKE SERVICE call returns a TIMEDOUT response.
  The task then issues another INVOKE SERVICE command and the
  same socket is allocated from the pool.  DFHSOS06 attempts to
  get the SOCKSEND lock, but this fails DUPLICATE_LOCK_OWNER
  and an ASOB abend occurs.
  Further ASOB abends may occur, and CICS may end up in a
  deadlock on the SOCKSEND and SOMGLOCK locks.
  Additional keywords: SO0001 SO0002
  

Problem conclusion

• DFHSOS06 has been modified to ensure that if a failure occurs
  during a send, the socket's in_send flag is turned off.
  Additionally, DFHSOS06 will always release the SOCKSEND lock if
  an error occurs during a send.
  

Temporary fix

•             *********
              * HIPER *
              *********
  FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  PI61505 UI37997

Modules/Macros

• DFHSOS00 DFHSOS01 DFHSOS02 DFHSOS03 DFHSOS04 DFHSOS05 DFHSOS06
  DFHSOS07 DFHSOS08 DFHSOS09 DFHSOS10 DFHSOS11 DFHSOS12 DFHSOS13
  DFHSOS14 DFHSOS15 DFHSOS16 DFHSOS17 DFHSOS18 DFHSOS19 DFHSOS20
  DFHSOS21 DFHSOS22 DFHSOS23
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R900 PSY UI37997

     UP16/05/27 P F605 ¢

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.