PH30759: CONL HUNG AFTER ISSUING A CEMT SET JVMSERVER COMMAND

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• From the dump we can see that the system T8 in the JVM is
  acquired by the XXXX task.  The thread then gets stuck getting
  into the JVM because the entire JVM is locked due to heap and GC
  issues.
  
  The CONL task tries to do a SET JVMSERVER DISABLED PURGE
  command.  This acquires the JVMSRVLK in DFHSJJS and then goes
  through each active task issuing purges against them.  The purge
  goes to DFHXMIQ and then to DFHSJTH because the target task is
  currently running in the JVM.  DFHSJTH needs to get the system
  T8.  The TCB is allocated to the XXXX task so the CONL task has
  has to suspend.  The JVMSRVLK should be released before waiting
  on JVMTHRED but DFHSJTH did not detect that the lock was already
  held.  This meant that the JVMTHRED wait was issued still
  holding the lock.  That caused all the other Java tasks to back
  up waiting for the lock.
  
  ADDITIONAL KEYWORDS: CONL JVMSRVLK JVMTHRED DFHSJTH
  KIXREVxxx
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS Users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: A task suspends on the system thread    *
  *                      (JVMTHRED) whilst holding the JVM       *
  *                      server lock (JVMSRVLK).                 *
  *                      This causes all other tasks requiring   *
  *                      the JVMSRVLK to suspend.                *
  ****************************************************************
  A SET TASK PURGE is issued against a Java task, this operation
  requires the system T8 for the JVMSERVER that the Java task is
  running in.  The system T8 is obtained but this task then gets
  held up, for example if Garbage Collection has control of the
  JVM at this time.
  A SET JVMSERVER PURGE command is then issued to PURGE the
  JVMSERVER, this task obtains the JVMSRVLK exclusively and then
  attempts to purge each task that is using the JVMSERVER. The
  system T8 is required for the purge so this task tries to obtain
  it. The system T8 however is still allocated to the SET TASK
  PURGE request that is currently held up by Garbage Collection.
  The SET JVMSERVER task now suspends on JVMTHRED and waits for
  the system T8 to become available. This wait is issued without
  releasing the JVMSRVLK.
  As a result, all other tasks requiring the JVMSRVLK suspend.
  

Problem conclusion

• CICS code has been updated to ensure that the JVMSRVLK is
  released before suspending on JVMTHRED.
  

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:

  UI73178 UI73180 UI73181 UI73182

Modules/Macros

• DFHSJDM  DFHSJDUF DFHSJJS  DFHSJST  DFHSJTH
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R000 PSY UI73182

     UP20/12/18 P F012 ¢

• R100 PSY UI73181

     UP20/12/17 P F012 ¢

• R200 PSY UI73180

     UP20/12/17 P F012 ¢

• R300 PSY UI73178

     UP20/12/17 P F012 ¢

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.