PI34146: Repeated start and stop or re-deploy of application resulted in OutOfMemory

8.5.5.6: WebSphere Application Server V8.5.5 Fix Pack 6
8.5.5.7: WebSphere Application Server V8.5.5 Fix Pack 7
8.5.5.8: WebSphere Application Server V8.5.5 Fix Pack 8
8.5.5.9: WebSphere Application Server V8.5.5 Fix Pack 9
8.5.5.10: WebSphere Application Server V8.5.5 Fix Pack 10
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
8.5.5.20: WebSphere Application Server V8.5.5.20
8.5.5.18: WebSphere Application Server V8.5.5 Fix Pack 18
8.5.5.19: WebSphere Application Server V8.5.5 Fix Pack 19
8.5.5.16: WebSphere Application Server V8.5.5 Fix Pack 16
8.5.5.21: WebSphere Application Server V8.5.5.21

APAR status

• Closed as program error.

Error description

• The problem is an OutOfMemory which is noticed after repeated
  application start/stop or re-deploy during testing  which
  results in eventual OutOfMemory in  the java heap.   The OOM is
  attributed to 2  further leaking threads "Alarms per second
  thread for TimerManagerRef"  and "TimerManagerRef:AlarmManager"
  which stay alive forever.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server V8.5                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: OutOfMemory is attributed to 2          *
  *                      leaking threads "Alarms per second      *
  *                      thread for TimerManagerRef"  and        *
  *                      "TimerManagerRef:AlarmManager"          *
  *                      which stay alive forever.               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The Application Class Loader is used to load the AlarmManager
  daemon threads. Since they are daemon threads they remain
  for the life of server holding the heavy Application Class
  Loader, resulting in Out Of Memory.
  

Problem conclusion

• The code has been changed to use the ExtClassLoader to load
  the daemon threads.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 8.5.5.6.  Please refer to the Recommended Updates
  page for delivery information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

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:

Fix information

• Fixed component name

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels

• R850 PSY

     UP