PK86574: MESSAGES ON A SUBSCRIPTION ARE DELIVERED AHEAD OF RECOVERED MESSAGES

Fixes are available

APAR status

Closed as program error.

Error description

Messages from the messaging engine to the SIBus code in the
client are delivered ahead of messages from the SIBus client
to the MessageListener.
When read-ahead is enabled, it means that a number of messages
may be streamed to the client by the messaging engine, and
held in an in-memory 'proxy queue' in the client.
When Session.recover() is called, all unacknowledged messages
are returned to the durable subscription inside the messaging
engine. However, the other messages already streamed to the
client are not returned. This may result in a number of
messages being redelivered to the client before the messages
that were recovered.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  Users of the default messaging provider     *
*                  for IBM WebSphere Application Server        *
*                  Version 6.1 and Version 7.0                 *
****************************************************************
* PROBLEM DESCRIPTION: Messages are delivered out of           *
*                      order after Session.recover() is        *
*                      called from an application connecting   *
*                      to a messaging engine over a network    *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
After an application (that is the sole consumer from a
queue or subscription) calls Session.recover, the
delivery of messages should restart after the last
acknowledged message.

However, when an application is connected to a messaging
engine in a Service Integration Bus over a network, messages
might be delivered out of order after Session.recover is called.

If read ahead is enabled on the consumer (default for
non-shared subscriptions), many messages might be delivered to
the application before the last unacknowledged message that
was returned to the destination when Session.recover was called.

If read ahead is disabled on the consumer (default for queues
and shared subscriptions) a single message might be delivered
to the application before the last unacknowledged message
returned to the destination when Session.recover was called.

The problem is caused because the messaging engine sends
messages to the WebSphere Application Server JMS client
code before those messages are delivered to the application.
These messages are held in an in-memory 'proxy queue' within
the client.
When Session.recover is called, messages on the proxy queue
(that have not yet been seen by the application) are not
purged as part of the recover, so are delivered to the
application before the messages that were recovered.

Problem conclusion

The fix for this APAR is disabled by default.
To enable the fix, configure the following property in the
sib.properties file for all JVMs where client applications
require the fix:
sib.comms.StrictRedeliveryOrdering=true

Setting properties in the sib.properties file is described in
the "Setting tuning properties by editing the sib.properties
file" section of the WebSphere Application Server information
center.

With the fix for this APAR applied and enabled, all messages
that have been delivered to the JMS client code are returned
to the destination before Session.recover returns.
This means that delivery of messages restarts after the last
acknowledged message.

The fix for this APAR does not affect consumption of
messages from destinations containing only BestEffort or
Express NonPersistent messages. This is because Session.recover
does not recover messages of these reliability levels, instead
they are discarded when Session.recover is called.

If a destination contains messages with a mixture of
reliability levels, then calling Sesison.recover might cause
messages with a BestEffort or Express NonPersistent
reliability to be discarded without ever having been delivered
to the application.

The fix for this APAR is currently targeted for inclusion in
fix pack 6.1.0.27 and 7.0.0.7.  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 number
PK86574
Reported component name
PLAT MSG COM
Reported component ID
620600101
Reported release
200
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2009-05-14
Closed date
2009-06-18
Last modified date
2009-06-22

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
PLAT MSG COM
Fixed component ID
620600101

Applicable component levels

R200 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"6.1","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
29 December 2021

Tips

PK86574: MESSAGES ON A SUBSCRIPTION ARE DELIVERED AHEAD OF RECOVERED MESSAGES

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

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

Fixed component ID

Applicable component levels

R200 PSY

Document Information

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