CODEWITHSUNDEEP
webspherelinkageerror
Yoni
Yoni

Reputation: 10321

LinkageError on WebSphere 9 for javax.transaction.* classes

I have a web application that used to run fine on many web servers (tomcat, jboss, weblogic and websphere). Now, however, it has an error when deploying on WebSphere 9.

The app contains the jar javax.transaction-api-1.2. Some of its classes, e.g., javax.transaction.xa.XAResource, are also included in Java SE, but not all of them. Some are specific to Java EE and are required by some 3rd-party libraries in my app. The app is always deploying with child-first (parent-last) classloader. WebSphere 9 throws this error during startup when the app tries to load the Oracle JDBC driver:

java.lang.LinkageError: loading constraint violation: loader "com/ibm/ws/classloader/CompoundClassLoader@7157be44" previously initiated loading for a different type with name 
"javax/transaction/xa/XAResource" defined by loader "com/ibm/oti/vm/BootstrapClassLoader@422c7b1b"

Note that we aren't actually using XA transactions in the app, we are using regular transactions.

On other servers, and previous versions of WebSphere, it was never a problem. The server didn't care that we load XAResource from inside the war, even if it was previously loaded somewhere in the server. Now WebSphere 9 is different, it says that the app classloader already loaded this class from the server, but I don't know why or when did this happen.

Any idea how to solve this?

Upvotes: 0

Views: 376

Answers (2)

Yoni
Yoni

Reputation: 10321

At the end we did two things to solve this problem.

1) We upgraded the jta jar to version 1.3 (link here). This jar solves the problem by avoiding duplicate classes - it contains only J2EE classes and omits the J2SE classes that are already included in the JVM. 2) We upgraded WebSphere server from 9.0.0.7 to 9.0.0.11.

At the time, I suspected just upgrading the jar should suffice, but our QA had some issues with it and they also upgraded the server. Due to lack of time, we didn't investigate it further and just decided to do both.

Upvotes: 0

Jarid
Jarid

Reputation: 2018

Remove the transaction API from your application. JTA 1.2 is already included in the server and provides no value in your applications. It's always risky to bring Java EE/SE APIs in a parent-last class loader unless you are 100% certain that they are technically necessary, because they can lead to issues like this one.

I can't say how this worked in previous server versions (there have been some Java-level changes in enforcing linkage issues like this), but the solution is reasonably straightforward.

Upvotes: 1

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