PK82910: INSUFFICIENT INFORMATION AVAILABLE TO DIAGNOSE APPLICATIONS BLOCKED BECAUSE THE MAXIMUM NUMBER OF MESSAGES HAVE BEEN LOCKED

Fixes are available

APAR status

Closed as program error.

Error description

A condition was encountered where the event sequencing
component of IBM WebSphere Process Server had locked
the number of messages it specified as a maximum on a
queue point in a bus.
Processing of messages already locked on the destination
was dependent on processing of messages arriving on the queue
point. However, these messages would not be delivered
by the bus until the number of messages already locked
by the application was reduced.

The function of the default messaging provider was correct.
However, the information available in the application server
JVM logs was insufficient to quickly identify the problem.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  Users of the default messaging provider for *
*                  WebSphere Application Server V6.1 and V7.0  *
****************************************************************
* PROBLEM DESCRIPTION: Insufficient information is             *
*                      available to diagnose problems with an  *
*                      application consuming messages from a   *
*                      bus destination, that is unable to      *
*                      process new messages because it has     *
*                      already locked the number of            *
*                      messages it specified as a maximum.     *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
The majority of messaging applications consume each message
on a dedicated thread within an application server.
This include message-driven bean applications.
For these applications, a number of diagnostic tools
are already available to diagnose a situation where messages
are not being processed. These include WSVR0605W messages in
the JVM logs indicating hung threads, and javacores taken
from the application servers that host the applications
processing the messages and the messaging engine.

However, there are circumstances where an application
consuming messages from a queue point, within the default
messaging provider, can become unable to process messages
without multiple threads active in javacores.
This applies to applications designed to be allocated messages
on a bus destination, but not necessarily process and consume
them immediately. This type of application specifies a maximum
number of messages that can be allocated to the application by
the bus.
Applications of this type are susceptible to a situation
where the maximum number of messages have been allocated by
the bus, but none of those messages can be processed until
another event occurs.
This leaves a number of messages in Locked, or Removing, state
on the queue point (or subscription) in the bus, with a
Redelivery Count of zero on each message, and possibly no
errors logged in the JVM logs of the application servers.

If the event blocking processing requires a manual action, then
consumption of all messages on the destination is blocked
until that manual action is performed.
If the event blocking processing is the processing of another
message on the queue, which cannot be delivered because the
maximum has been reached, then the application has induced a
deadlock.

The only applications of this type currently known, are
WebSphere Process Server modules with event sequencing enabled.

Problem conclusion

Two new warning log entries have been added to aid problem
diagnosis for applications susceptible to blocking in this way.

These warning messages are only output for destinations with
the following context property set:
Name:          MsgBlockWarningInterval
Type:          Integer
Valid values:  Positive number of seconds
For information on configuring a context property for a
destination, see the "Configuring context properties for a bus
destination" section of the WebSphere Application Server
information center.

Although this context property is introduced to aid diagnosis
of problem with applications in the specific category described
above, it can also supplement the existing problem
diagnosis information available for message-driven bean
applications consuming against bus destinations in WebSphere
Application Server on z/OS.

With this context property enabled for a destination, the
following warning log entries can be output to the JVM logs
of the application server hosting the messaging engine:

CWSIP0182W: Consumer {0} of resource {1} on messaging engine
{2} has been blocked for {3} seconds.
This is entry is logged when consumer has reached the maximum
number of messages that can be allocated to it by the
bus, and those same messages have not been consumed for the
number of seconds specified in the MsgBlockWarningInterval
context property:

CWSIP0183I: Consumer {0} of resource {1} on messaging engine
{2} is no longer blocked.
This entry is logged if a consumer for which a CWSIP0182W
entry was previously logged resumes consumption of messages.

The fix for this APAR is currently targeted for inclusion in
fixpack 6.1.0.25 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
PK82910
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
2009-03-19
Closed date
2009-03-24
Last modified date
2009-08-27

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

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PK82910: INSUFFICIENT INFORMATION AVAILABLE TO DIAGNOSE APPLICATIONS BLOCKED BECAUSE THE MAXIMUM NUMBER OF MESSAGES HAVE BEEN LOCKED

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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