[rules-users] StatefulKnowledgeSession synchronization problem

[Edson Tirelli]

   I believe this problem is fixed in trunk already. Would you please try
your own use case, just in case?

   Thanks,
      Edson

2010/2/8 heldeen <heldeen at overstock.com>

>
> Hello,
>
> Using Drools 5.1.0.M1.
> I am running into a blocking problem when I concurrently try to update a
> fact in my knowledge session, which is fireUntilHalt() in its own thread,
> from another thread, an updator thread. I know that only these 2 threads
> are
> ever accessing each knowledge session.
>
> Has anyone else run into this problem?
>
> I am including the relavant details and can provide a working example if
> need be. The block happens randomly anywhere from 20 - 1000's of sessions.
>
> I consistantly get this stack trace from the blocked thread:
>
> org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1540)
>
> org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:1529)
>
> org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:1403)
>
> org.drools.impl.StatefulKnowledgeSessionImpl.update(StatefulKnowledgeSessionImpl.java:248)
> ...
>
> I have a simple drools knowledge base that is a basic rule flow [Start ->
> Rule Flow Group -> Event Wait -> Rule Flow Group -> End]
>
> I build a knowledge base like this:
>
>      KnowledgeBaseConfiguration knowledgeBaseConfiguration =
> KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
>      knowledgeBaseConfiguration.setOption(AssertBehaviorOption.EQUALITY);
>      knowledgeBaseConfiguration.setOption(MBeansOption.ENABLED);
>
>      KnowledgeBase knowledgeBase =
> KnowledgeBaseFactory.newKnowledgeBase(knowledgeBaseConfiguration);
>
>      KnowledgeBuilder kbuilder =
> KnowledgeBuilderFactory.newKnowledgeBuilder();
>      kbuilder.add(ResourceFactory.newClassPathResource(CHANGE_SET_XML,
> getClass()), ResourceType.CHANGE_SET);
>      if (kbuilder.hasErrors()) {
>        throw new IllegalArgumentException("Unable to build knowledge");
>      }
>      knowledgeBase.addKnowledgePackages(kbuilder.getKnowledgePackages());
>
>
> My basic test fact is:
>
> public class Fact() {
>
>  String name;
>  boolean isReady;
>
>  //getters and setters
> }
>
> I have a fixed thread pool (Sun's ExecutorService.newFixedThreadPool() with
> 20 threads). Each session is submitted from a for loop of 0 to 100000 where
> it generates a simple fact with Fact.name = "fact"+i and Fact.isReady =
> false, then puts it in an array like so:
> final Object[] facts...
> fixedPoolExecutor.submit(new Runnable() {
>  @Override
>  public void run() {
>    StatefulKnowledgeSession knowledgeSession = null;
>    try {
>      knowledgeSession = knowledgeBase.newStatefulKnowledgeSession();
>      //put it in a ConcurrentHashMap keyed by session id.
>      ...
>      for (Object fact : facts) {
>        knowledgeSession.insert(fact);
>      }
>
>      //add session completion halt event - omiting other unused methods
>      knowledgeSession.addEventListener(new ProcessEventListener() {
>
>        @Override
>        public void afterProcessCompleted(ProcessCompletedEvent event) {
>          knowledgeSession.halt();
>        }
>      });
>
>      knowledgeSession.startProcess(PROCESS_ID);
>
>      knowledgeSession.fireUntilHalt();
>    } finally {
>      if (knowledgeSession != null) {
>        knowledgeSession.dispose();
>      }
>    }
> });
>
> I have a single thread executor (Sun's
> ExecutorService.newSingleThreadExecutor()) that is used to update these
> sessions (basically set the Fact.isReady from false to true for the
> EventWait in my rule flow):
>
> final int sessionId...
> final Object[] facts...
> singleThreadExecutor.submit(new Runnable() {
>  @Override
>  public void run() {
>    StatefulKnowledgeSession knowledgeSession = null;
>    try {
>      knowledgeSession = ... from ConcurrentHashMap based on sessionId
>
>      FactHandle factHandle = knowledgeSession.getFactHandle(fact);
>      if (null != factHandle) {
>        knowledgeSession.update(factHandle, fact);//This is where it blocks
> and never returns
>      } else {
>        knowledgeSession.insert(fact);
>      }
> });
>
> -Heath
> --
> View this message in context:
> http://n3.nabble.com/StatefulKnowledgeSession-synchronization-problem-tp195744p195744.html
> Sent from the Drools - User mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>



-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss by Red Hat @ www.jboss.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20100208/67ba4aa0/attachment.html