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HttpSession Object becoming null between sessions when using tomcat9 + Memcache

We have a java web application which was hosted in tomcat 8. For session Management , we have been using the memcache which maintains non sticky based sessions. This has been working fine without any issues.
Now there is a requirement to upgrade the tomcat from 8 to tomcat 9 and the upgradation with the necessary jars for the tomcat 9 has been done. After the upgradation, we are facing an issue in the application where the session is becoming null. Some of the link in the app associated with the session are working fine and some of them when clicked gets me logged out of the session. Checking the logs, I see the session object null.
The memcached jars used as part of the tomcat 9 and copied under tomcat9/lib
memcache-session-manager-2.3.2
memcache-session-manager-tc9-2.3.2
jettison-1.1.jar
spymemcached-2.12.0
http-core-4.3
http-core-nio-4.3
we are using the 3rd party Serialization for this use case and they are also copied in the tomcat lib folder
kryo-3.0.3.jar
kryo-serializers-0.37.jar
minlog-1.3.0.jar
msm-kryo-serializer-1.9.3.jar
objenesis-2.1.jar
protobuf-java-2.6.1.jar
reflectasm-1.10.1.jar
With these jars , I am able to see the tomcat startup without any issues.
**<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
memcachedNodes="n1:ip:port"
lockingMode="auto"
sticky="false"
requestUriIgnorePattern= ".*\.(png|gif|jpg|css|js)$"
sessionBackupAsync= "false"
sessionBackupTimeout= "100"
copyCollectionsForSerialization="false"
transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"/>**
Followed the below link for setting up the memcache configuration in my application.
https://github.com/magro/memcached-session-manager/wiki/SetupAndConfiguration
Please help me if i am missing anything in the configuration.
Thanks
Pradeep

Have solved this issue by removing the param **requesturiignore pattern ** from the context.xml as this was creating different sessions.

Wildfly ClassCastException

I am migrating a legacy web application from Jboss AS7.1 to Wildfly 8.2. The application works perfectly on AS7. It stores a User object in the session using session.setAttribute() and retrieves it in various places where it needs to know the user details.
The application works fine on the first start of the Wildfly server. When I re-deploy the application (from Eclipse) it then fails when retrieving the session attribute with a ClassCastException (com.mycompany.User cannot be cast to com.mycompany.User). I cannot run the application without restarting the server completely. The application is a basic war deployment with a few dependencies in the lib folder.
I've run in debug and dumped the classloader name and can't see any problems. There is only 1 version of the User class in the application (it's inside a jar in the WEB-INF/lib folder). If I retrieve the session attribute as an Object and check 'obj instanceof User' it returns false. It seems to be holding onto something between deployments somehow but I can't find out what.
Has anyone come across anything similar?
Thanks

Toplink runtime error in Tomcat 6

Let me give a little background to give context to this question. Over the course of time, the application I have been assigned to work on lost the ability to be built and deployed as a full application. By that I mean the previous developer compiled the code in his local IDE, and dropped single class files, as opposed to building out proper JARs and WARs to be deployed out to tomcat. So I have been tasked to clean up the project so it is a standard deployable app again. So to sum up the important part, the application exists in a working format on a windows tomcat environment, that hasn't had a clean deploy in a long time, my goal is to make the app buildable and deployable via a jenkins CI server to a tomcat instance running on a Linux server. Now on to the problem. I get the following toplink exception in one application module.
Local Exception Stack:
Exception [TOPLINK-6007] (OracleAS TopLink - 10g (9.0.4) (Build 031126)): oracle.toplink.exceptions.QueryException
Exception Description: Missing descriptor for [class edu.cornell.finsys.datamodel.AccountDTO].
Query: ReadObjectQuery(edu.cornell.finsys.datamodel.AccountDTO)
I have verified that the toplink mapping file has been loaded by tomcat, and the AccountDTO is mapped in the file. To double check that, I have moved the mapping file out, and I get a completly different error at load time. I know the file mapping is correct, as it worked correctly on the old server. I don't know what else could be causing the toplink exception.
For more information, I am on tomcat version 6.0.37, Java version 1.6.0_45, toplink version 9.0.4.031126
Any ideas?

This may be it; right from Metalink:
Cause:
This is an issue with loading the sessions.xml file, once when the application was first deployed using that application's classloader and then not reloading the session when the application was redeployed and a new XMLContext was created. The caused us to attempt to use a session that had been loaded with a different classloader than the current application.
Possible solution:
The issue occurs when TopLink is part of the main classpath (Eg: Applib directory rather than stored in the ear file). When this happens, the static SessionManager has trouble finding descriptors the second and subsequent times an application is deployed. Basically the descriptors are indexed by class. When the application is redeployed, the classes used for the indexing are unloaded and new versions of those classes appear. This causes "Descriptor not found" exceptions.
Potential Workarounds
Put the toplink.jar file in the ear.
Write some code to manually clean up when the toplink application is torn down.
For certain architectures they may be able to use the version sessionManager.getSession() that allows the session to be refreshed.
Workaround 3 is best and very feasible. The session has to be lazily
obtained from the SessionManager and held in an application code
variable. When the application is restarted its handle on the TopLink
session will be null. The session can then be obtained from the
SesssionManager using the getSession(XMLLoader xmlLoader, String
sessionName, ClassLoader objectClassLoader, boolean
shouldLoginSession, boolean shouldRefreshSession) API with
shouldRefreshSession set to true. This will ensure that the old
session (if any) is logged out and removed from the SessionManager
before a new one is created.
Did any of the workarounds help?

How to make J2EE weblogic application resilient to database problems

I have a Web application running on Oracle Weblogic Server 11g.
It uses a datasource defined in the application server to connect to the Oracle Database (11g too), its class is
oracle.jdbc.xa.client.OracleXADataSource
If for some reason the database becomes not present and then comes
backs, the application is running ok (it gets exceptions while trying
to access the db but this is fine and then can again get some new
connections when the db comes back)
However, if the database is down during weblogic server startup,
the datasource is not deployed on the server and the application
throws an exception because it has not any datasource available, the
deployment is marked as failed and of course nothing does repair this
automatically.
Is there a way to make the datasource be deployed even if the database is not present during server startup ? (such that the application becomes usable when the database is back)

Why do you want to deploy an application without a valid datasource?
You could possibly fake the datasource (create a dummy datasource with the same JNDI name) and assuming that the application does not validate datasource schema at startup you will get a semi-functional running application (which will fail with the first DB interaction).
When the real datasource is up and running you won't be able to switch to it. You will still have to restart the application server.
Update:
According to the J2EE spec (1.5 version) resources are binded during the deployment process. I believe that it is possible to implement a custom Factory that will return dummy / active datasource. Does it worth the effort to implement? ;)
EE.5.6.2 Deployer’s Responsibilities
Bind the resource manager connection factory reference to a resource manager connection factory that exists in the operational environment. The Deployer may use, for example, the JNDI LinkRef mechanism to create a symbolic link to the actual JNDI name of the resource manager connection factory. The re- source manager connection factory type must be compatible with the type de- clared in the res-type element.

The option you are looking for is "Connection Creation Retries", check this link
"If set and if the database is unavailable when the data source is created, WebLogic Server attempts to create connections in the pool again after the number of seconds you specify, and will continue to attempt to create the connections until it succeeds. This option applies to connections created when the data source is created at server startup ..."

set "Initial Capacity" http://docs.oracle.com/cd/E14571_01/web.1111/e13814/jdbc_tuning.htm#i1028616 to 0: weblogic on startup will not attempt to create any connection, and will not fail if the DB is not available.

oc4j enterprise manager console session timeout?

How can I change the session timeout for the OC4J Enterprise Manager console?
It times out too quickly between deployments in our development environment.

The default session timeout of an application in OC4J is 20 minutes. If you need to change the same for an application, you have to explicitly set the session timeout value in web.xml.
This holds good even for Enterprise Manager as well, which is deployed as the application ascontrol. The web.xml file of ascontrol will be available at $ORACLE_HOME/j2ee/OC4J_INSTANCE/config/applications/ascontrol/ascontrol/WEB-INF/web.xml. You will have to introduce the session-timeout element in this file at the appropriate location (usually at the end), so that the XML is valid. A restart of the OC4J instance is required.
Do note that, this comes with no guarantees, and it is better to confirm via Oracle Support if this configuration change is supported.
Alternatively, you can use admin_client.jar or admin.jar to deploy your application.