PK87413: WEBSPHERE MQ COMMON SERVICES THREAD POOL (WMQCOMMONSERVICES) WHEN FULL CAUSES DEADLOCK

Fixes are available

APAR status

Closed as program error.

Error description

It is possible for a sequence of events to occur that cause a
condition similar to a deadlock. If an application begins
processing and creates MQ JMS objects that require WMQ threads
(e.g. JMSConnection/Session), it is possible that the first
call to create an object succeeds, and a thread is obtained,
whereas the second callhas to wait for a thread to become
available.

Local fix

Therefore, the recommendation, even with any fix created as a
result
of these PMRs, is to configure the WMQ Thread pools to be large
enough to cope with the defined JMS connection/session limits.

Problem summary

****************************************************************
* USERS AFFECTED:  Users of IBM WebSphere Application Server   *
*                  Version 7.0 using WebSphere MQ as a JMS     *
*                  messaging provider                          *
****************************************************************
* PROBLEM DESCRIPTION: The WMQCommonServices thread pool       *
*                      becomes full and causes applications    *
*                      to deadlock                             *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
The WMQCommonServices thread pool becomes full and
applications using WMQ within WebSphere Application Server
become deadlocked waiting to create connections.
The following is an example of a thread caught in this deadlock:

java/lang/Object.wait(Native Method)
at java/lang/Object.wait(Object.java:167(CompiledCode))
at com/ibm/mq/jmqi/JmqiWorkerThread.
          syncExec(JmqiWorkerThread.java:106(Compiled Code))
at com/ibm/mq/jmqi/local/LocalHconn.
                               syncExec(LocalHconn.java:386)
at com/ibm/mq/jmqi/local/LocalMQ.
                              jmqiConnect(LocalMQ.java:5151)

The issue is caused by a limit being placed on the number of
long-lived WebSphere MQ resource adapter threads that can be
running within the application server - by creating these
threads within the WMQCommonServices thread pool.
As new threads are created by the WebSphere MQ resource
adapter whenever connections are created, the number of
threads should not be limited using a thread pool, as no limit
is placed on the number of WebSphere MQ connections that can
be created by users.

Problem conclusion

The fix for this APAR prevents long-lived WebSphere MQ
resource adapter threads from being created in the
(limited size) WMQCommonServices thread pool.
Instead, a JVM new thread is created each time a long-lived
WebSphere MQ resource adapter thread is required.

The fix for this APAR is currently targeted for inclusion in
fixpack 7.0.0.5. Please refer to the Recommended
Updatespage for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PK87413
Reported component name
PLAT MSG COM
Reported component ID
620800101
Reported release
300
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2009-05-27
Closed date
2009-06-29
Last modified date
2009-06-29

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
620800101

Applicable component levels

R300 PSY
UP

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
24 October 2021

Tips

PK87413: WEBSPHERE MQ COMMON SERVICES THREAD POOL (WMQCOMMONSERVICES) WHEN FULL CAUSES DEADLOCK

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

R300 PSY

Document Information

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