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SUP SSO: Webdynpro Bug on Netweaver 7.xx

This article deals with SUP SSO,  implemented via the SAP Netweaver Portal

Ok, this this not directly related to Sybase technology….BUT…SUP itself is not an identity management system , so for SSO for example, an additional identity management provider is needed.
Many customers are using the SAP Netweaver stack, with an LDAP user store for this purpose.
This is where I came across this bug, the system landscape looked like this:/wp-content/uploads/2012/12/landscape_165548.png
The Problem
The Java server nodes would frequently crash when they reached an out-of-memory condition.
The SAP Netweaver stack was therefore unstable, resulting in many failed logons for end user apps.
Root Cause: Webdynpro Session Termination Bug
The root cause was identified as a bug within the Webdynpro framework.
Webdynpro sessions are terminated in two different ways:

  1. Explicit:
    where the user clicks “logoff” in the Portal and a signal is sent to kill the session
  2. Implicit:
    where the browser is simply closed (or the user navigates to a different page),
    the connection lifetime value exceeds the global timeout value and a signal is
    sent to destroy the session.

A bug was identified where the signal sent to kill the session contained a blank/null value, resulting in a ‘Null Pointer Exception’ error.
The system expects a value within the signal but that value is blank. The end result is that the session is not terminated and accumulates in memory until the system is restarted. The size of memory retained will depend on the user session which ranged from a few Kb to several MB.
This is a screen-grap of the heap memory behaviour (taken using Wily introscope):
memory behaviour.png
As you can see, memory behaviour is erratic with server node restarts, forced cluster restarts and long running full Garbage collection, causing performance issues.
The bug was fixed with a patch, below is the official documentation covering the fix:

SAP Note Details Patches Applied
SAP Note 1644347 SAP_JTECHS
Title: HttpClientSessionListener failed to destroy client SAP_JTECHF

This bug affects the following releases:

Software Component                                                   Release
                                                                                      from            to
    SAP JAVA TECHNOLOGY SERVICES                        7.00   –       7.02
    SAP JAVA TECHNOLOGY SERVICES OFFLINE        7.00  –       7.02

As Netweaver & Enterprise Portal are new technologies within the Sybase community (not new themselves), this blog forms the start of a planned series to cover supportability topics for these platforms.

— Stephen
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