PM08450: WLM CALLBACK TIMEOUT INFINITE WAIT.

Fixes are available

APAR status

Closed as program error.

Error description

In WebSphere Application Server Version 7, if you sets the
WorkLoad Management (WLM) custom property
IBM_CLUSTER_CALLBACK_TIMEOUT to a value of 0,
this will cause the WLM selection logic on a nodeagent to wait
until it is called back before that thread will exit.

If you run into a scenario in which all of the cluster members
are currently shut down, but the nodeagent is running and an
EJB request is sent to the cluster, it will end up at the
nodeagent.  Because no cluster members are running, the thread
will continue to wait.  Given enough requests and enough
threads created on the nodeagent the cluster members may have
problems communicating with the nodeagent upon startup, which
in turn can prevent the cluster members from starting up again.


The Nodeagent systemout.log shows ORB threads being hung:

ThreadMonitor W   WSVR0605W: Thread "ORB.thread.pool : 94"
(000048f2) has been active for 678522 milliseconds and may be
hung.  There is/are 20 thread(s) in total in the server that may
be hung.
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:196)
at
com.ibm.ws.cluster.router.selection.WLMLSDRouter.select(WLMLSDRo
uter.java:268)

Local fix

As a workaround, the callback timeout (
IBM_CLUSTER_CALLBACK_TIMEOUT cell level property) can either be
set to a positive value, or it can be removed, in which
case the default value of 30 seconds will be used.

Problem summary

****************************************************************
* USERS AFFECTED:  Users of IBM WebSphere Application Server   *
*                  Version 7 who have configured the WorkLoad  *
*                  Management (WLM) Custom Property            *
*                  IBM_CLUSTER_CALLBACK_TIMEOUT to a value of  *
*                  0 (zero)                                    *
****************************************************************
* PROBLEM DESCRIPTION: WLM Callback Timeout Infinite Wait      *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
If you are using WebSphere Application Server Version 7 and
configure the WLM Custom Property
IBM_CLUSTER_CALLBACK_TIMEOUT, which was introduced
with APAR PK20304, to a value of zero, the intended effect is
that the WLM callback logic will be skipped entirely.  Due to
a code bug, this instead will cause the WLM callback logic to
run and with an infinite wait.  Although the client process
which sent these requests will eventually time out and move
onto other work, the callback threads on the server side will
continue to wait forever, which can lead to CPU, memory, and
other resource issues depending on how many callback objects
were created.

Problem conclusion

The code bug was fixed to ensure that when the value of zero
is specified for the IBM_CLUSTER_CALLBACK_TIMEOUT property,
that the effect will be the callback logic being skipped.

This APAR is applicable to Version 7 only and does not exist
in the v6.0.2 or v6.1 releases.

The fix for this APAR is currently targeted for inclusion in
fix pack 7.0.0.13.  Please refer to the Recommended Updates
page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Restarting the affected nodeagent(s) will clear out all of the
callback objects stuck in an infinite loop and free up all
threads affected.

Comments

APAR Information

APAR number
PM08450
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2010-02-24
Closed date
2010-04-13
Last modified date
2010-04-13

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

R700 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

PM08450: WLM CALLBACK TIMEOUT INFINITE WAIT.

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

R700 PSY

Document Information

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