PQ79098: NullPointerException observed when using Session Memory-to-memory replication

 A fix is available

4.0.7: WebSphere Application Server Version 4.0 Fix Pack 7



APAR status
Closed as program error.

Error description
When using session with memory-to-memory replication for
failover, NullpointerExceptions are observed in the Application
Server logs. This may also result in failover not happening as
expected with the Session Manager creating new sessions instead
of returning existing ones after an application server that
holds the original session is brought down.
The text of the exception might look like this.

[7/7/03 1:23:45:670 CDT] 464d6b2a DRSCacheApp E
DRSW0008E: Exception is: java.lang.NullPointerException at
com.ibm.ws.webcontainer.util.SimpleHashtable.get(SimpleHashtable
.java(Compiled Code))
at
com.ibm.ws.webcontainer.httpsession.SessionContextRegistry.getSe
ssionContextByName(SessionContextRegistry.java(Inlined Compiled
Code))
at
com.ibm.ws.webcontainer.httpsession.DRSHttpSessCache.acknowledge
(DRSHttpSessCache.java(Compiled Code))
at com.ibm.ws.drs.DRSJMS.onMessage(DRSJMS.java(Compiled Code))
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All WebSphere Application Server users.      *
****************************************************************
* PROBLEM DESCRIPTION: A NullPointerException is seen in DRS   *
*                      logs on a receipt of a DRS ack message. *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When changes are made to an existing sessiong a DRS instance
sends back an ack message as a response to a received
removeEntry message. In this returning ack, the propkey contains
the application name whose session is to be removed. A null
propkey is encountered in a received ack, and this causes a
NullPointerException.
Problem conclusion
The cause of the problem was a dca.retDCMPool statement that
was being invoked twice on the same DCM, causing two references
of the same DCM to be entered into the DCMPool.
Temporary fix Comments
APAR information
APAR number PQ79098
Reported component name WAS NETWRK DEPL
Reported component ID 5630A2200
Reported release 400
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Submitted date 2003-10-01
Closed date 2003-10-01
Last modified date 2003-10-01

APAR is sysrouted FROM one or more of the following:
PQ76310

APAR is sysrouted TO one or more of the following:

Modules/Macros
DRS          

SRLS

Fix information
Fixed component name WAS NETWRK DEPL
Fixed component ID 5630A2200

Applicable component levels
R400 PSY    UP


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > General
Operating system(s):
Software version: 400
Software edition:
Reference #: PQ79098
IBM Group: Software Group
Modified date: Oct 1, 2003