PK81437: WLM PROXY INCORRET ROUTING DUE TO NON-UNIQUE HASHCODES

Fixes are available

APAR status

Closed as program error.

Error description

There is path in the Workload Management (WLM) routing
mechanisms on the WebSphere Proxy Server which handle the
routing of HTTP requests where the HashCode of two different
targets (different host/port combinations) can resolve to the
same value.  This results in incorrect routing behaviors from
the WLM selection code.

The problem occurs when using short host names that are
lexicographically close to each other (eg, host01, host02) and
port numbers that are also as close (eg, 9082, 9081).  As a
workaround, you can either change the port numbers to be more
disparate, or use fully qualified host names to virtually
eliminate the chance of a hashCode collision.

Local fix

```
n/a
```

Problem summary

****************************************************************
* USERS AFFECTED:  Users of the IBM WebSphere Application      *
*                  Server Proxy in V6.1 and V7.0               *
****************************************************************
* PROBLEM DESCRIPTION: WLM Proxy incorrect routing due to      *
*                      non-unique hashcodes.                   *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
There is path in the Workload Management (WLM) routing
mechanisms on the WebSphere Proxy Server which handle the
routing of HTTP requests where the HashCode of two different
targets (different host/port combinations) can resolve to the
same value.  This results in incorrect routing behaviors from
the WLM selection code.

Problem conclusion

The problem occurs when using short host names that are
lexicographically close to each other (eg, host01, host02) and
port numbers that are also as close (eg, 9082, 9081).  This
APAR addresses the issue by modifying the hashCode of the
relevant target objects to ensure that they will be unique
given two targets with nearly identical values in the hosts
and ports.

As a workaround, you can either change the port numbers to be
more disparate, or use fully qualified host names to virtually
eliminate the chance of a hashCode collision.

The fix for this APAR is currently targeted for inclusion in
fix packs 6.1.0.27 and 7.0.0.5.  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
PK81437
Reported component name
WEBSPHERE APP S
Reported component ID
5724J0800
Reported release
61W
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2009-02-26
Closed date
2009-05-18
Last modified date
2009-05-18

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

R61A PSY
UP
R61H PSY
UP
R61I PSY
UP
R61P PSY
UP
R61S PSY
UP
R61W PSY
UP
R61Z PSY
UP
R700 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:
28 December 2021

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PK81437: WLM PROXY INCORRET ROUTING DUE TO NON-UNIQUE HASHCODES

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

R61A PSY

R61H PSY

R61I PSY

R61P PSY

R61S PSY

R61W PSY

R61Z PSY

R700 PSY

Document Information

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