Do not start long-running conversations in direct calls to EJBs on async call

[egoosen]

I'm getting the above exception after a long running process completes on a Conversation scoped POJO.

The process gets kicked off from a JSF page. I made it asynchronous because I'm using the a4j:progressBar, which polls this bean.

1. Please advise me on when/how to start the conversation.


2. How to handle exceptions thrown from an asynchronous call, currently no error appears to the user. (Added the try/catch now...so will test and see if it displays the error)


3. I've packaged my application as an EAR running on JBoss-4.2.3GA, do I need to add the @Transcational annotation to the index() method?

Here's the code

@Name("indexer")
@Scope(ScopeType.CONVERSATION)
public class IndexerBean  {

        @Logger
        private Log log;

        static final int BATCH_SIZE = 1000;

        private boolean enabled = false;
        private boolean buttonRendered = true;
        private float index;
        private long total;
        private long percentage = -1;

        @In
        EntityManager entityManager;

        @In
    FacesMessages facesMessages;

        private Stopwatch stopwatch = new Stopwatch();

        @Asynchronous
        public String startProcess(IndexerBean indexerBean){
                indexerBean.setEnabled(true);
                indexerBean.setButtonRendered(false);
                indexerBean.index();
                return null;
        }

        @Begin(join=true)
        public void index() {
                stopwatch.start();

                Session session = (Session)entityManager.getDelegate();

                session.setFlushMode(FlushMode.MANUAL); //Disable flush operations
                session.setCacheMode(CacheMode.IGNORE); //Disable 2nd-level cache operations

                final FullTextSession ftSession =
                        org.hibernate.search.Search.createFullTextSession( session );

                indexAllClasses(ftSession, ProductInfo.class);

                stopwatch.stop();
                setButtonRendered(true);
        }

        @SuppressWarnings("unchecked") @End
        private void indexAllClasses(FullTextSession fullTextSession, Class... entityTypes){
                try {
                        //First calculate the total records to index
                        for (Class entityType : entityTypes){
                                Query query = entityManager.createQuery("select COUNT(e) from "+entityType.getName()+" e");
                                total += (Long)query.getSingleResult();
                        }
                        //Perform indexing
                        for (Class entityType : entityTypes){
                                //read the data from the database
                                //Scrollable results will avoid loading too many objects in memory
                                ScrollableResults results = fullTextSession.createCriteria( entityType )
                                .scroll( ScrollMode.FORWARD_ONLY );

                                while( results.next() ) {
                                        index++;
                                        percentage = (long)((index / total) * 100);
                                        fullTextSession.index( results.get(0) );
                                        if (index % BATCH_SIZE == 0) {
                                                fullTextSession.clear();
                                        }
                                }
                        }
                } catch (Throwable t) {
                        log.error("Exception during indexing operation.", t);
                        facesMessages.add(Severity.ERROR, "Exception during indexing operation. See log for details.");
                }
        }

        public long getPercentage() {
                return percentage;
        }

        public long getRunningTime(){
                return stopwatch.getRunningTime();
        }

        public boolean isEnabled() {
                return enabled;
        }

        public void setEnabled(boolean enabled) {
                this.enabled = enabled;
        }

        public boolean isButtonRendered() {
                return buttonRendered;
        }

        public void setButtonRendered(boolean buttonRendered) {
                this.buttonRendered = buttonRendered;
        }

}

[gonorrhea]

First of all, which component is the EJB?

@Transactional defaults to REQUIRED, similar to tx support/semantics in EJB3.

Have you tried moving the @Begin to the startProcess() method (wild guess here).

If that doesn't work, try to start the LRC via the pages.xml or s:link, if possible (i.e. before the @Asynchronous method call).

[egoosen]

I'm not using an EJB, so I'm not sure why I got that error.

I made some changes which seems to have fixed my problems.

I removed the @Begin(join=true) annotation from the index() method.
I'm starting the conversation when the user clicks the Start Process button.

<s:button action="#{indexer.startProcess(indexer)}" rendered="#{indexer.buttonRendered}" value="Start Process" propagation="begin">
     <a4j:support event="onclick" eventsQueue="async" requestDelay="200" ignoreDupResponses="true" reRender="progressPanel2" ajaxSingle="true"/>
</s:button>

I kind of based my code around this example, but I didn't like the author's approach of starting the conversation with a button click, and then starting the process with a second button click...strange.

I don't seem to need the @Transactional annotation, since the process worked fine without it.