[jira] Assigned: (ODE-503) Multithreading issue in ...rtrep.v2.EXTENSIONACTIVITY

["Tammo van Lessen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ODE-503?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tammo van Lessen reassigned ODE-503:
------------------------------------

    Assignee: Tammo van Lessen

> Multithreading issue in ...rtrep.v2.EXTENSIONACTIVITY
> -----------------------------------------------------
>
>                 Key: ODE-503
>                 URL: https://issues.apache.org/jira/browse/ODE-503
>             Project: ODE
>          Issue Type: Bug
>          Components: BPEL Runtime
>    Affects Versions: 2.0
>            Reporter: Jürgen Schumacher
>            Assignee: Tammo van Lessen
>             Fix For: 2.0
>
>
> We have experienced a problem in the execution of extension activities. I suppose it's caused by two process instances of the same BPEL process that invoke a single extension activity at the same time that has not yet been executed since hydration.
> The error stacktrace is something like this:
> java.lang.IllegalArgumentException: type: -1
> 	at org.apache.xerces.dom.DeferredDocumentImpl.getNodeObject(Unknown Source)
> 	at org.apache.xerces.dom.DeferredElementNSImpl.synchronizeData(Unknown Source)
> 	at org.apache.xerces.dom.ElementNSImpl.getNamespaceURI(Unknown Source)
> 	at org.apache.ode.utils.DOMUtils.getElementQName(DOMUtils.java:691)
> 	at org.apache.ode.bpel.rtrep.v2.EXTENSIONACTIVITY.run(EXTENSIONACTIVITY.java:51)
>              ...
> (sometimes it's a NullPointerException instead)
> This line 51 is
>      	final QName extensionId = DOMUtils.getElementQName(_oext.nestedElement.getElement());
> I searched for "java.lang.IllegalArgumentException at org.apache.xerces.dom.DeferredDocumentImpl.getNodeObject" and found an older message in the xerces mailing list suggesting that the cause for this could be that the DOM implementation is not thread-safe. So I did a little patch in org.apache.ode.utils.SerializableElement and added a line to readObject(...):
>   private void readObject(java.io.ObjectInputStream in)
>                    throws IOException, ClassNotFoundException {
>     try {
>       e = DOMUtils.stringToDOM((String)in.readObject());
>       DOMUtils.getElementQName(e);  // <-- this one is new
>       ...
> Now the error doesn't occur anymore (as far as I can tell), because whatever is changed in the DOM object during the first access of the element's QName has already changed during process hydration and the first invocation does only read the DOM object. 
> This is probably the most simple way to fix the issue, but there may be better possibilities (maybe reading the QName from the nested DOM during instance creation/deserialization of EXTENSIONACTIVITY and storing it for later access in a member variable? that would be also a small performance improvement), but I'll leave this decision to you. I can also provide a proper patch if you tell me which way to go. 
> Cheers,
> Juergen

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