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Concurrency issue with LocalTaskService
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created by <a href="https://community.jboss.org/people/jkranes">Jon Kranes</a> in <i>jBPM</i> - <a href="https://community.jboss.org/message/817047#817047">View the full discussion</a>
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<div class="jive-rendered-content"><p>I am running into a concurrency issue in my JBPM 5.4 application.  At first I thought it was related to thread safety of the StatefulKnowledgeSession issue discussed elsewhere, but I am able to recreate the issue without any session at all.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I am using the Spring JtaTransactionManager with annotated transaction boundaries, with MySQL, and running on AS 7.1.1.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>The Spring configuration looks like this:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-xml"><span class="jive-xml-tag"><jee:jndi-lookup id="emf" jndi-name="persistence/myEmf"/></span><span class="jive-xml-tag"><bean id="sel" class="org.drools.SystemEventListenerFactory"factory-method="getSystemEventListener" /></span><span class="jive-xml-tag"><bean id="jbpmTaskService" class="org.jbpm.task.service.TaskService"c:emf-ref="emf" c:systemEventListener-ref="sel" /></span><span class="jive-xml-tag"><bean id="localTaskService" class="org.jbpm.task.service.local.LocalTaskService" c:taskService-ref="jbpmTaskService" /></span><span class="jive-xml-tag"><bean id="jpaDialect" class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" /></span><span class="jive-xml-tag"><bean id="txManager" class="org.springframework.transaction.jta.JtaTransactionManager" /></span><span class="jive-xml-tag"><tx:annotation-driven transaction-manager="txManager" /></span></code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>And the code triggering the problem is this:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code">
List<TaskSummary> tasks = localTaskService.getTasksAssignedAsPotentialOwner(assignee, "en-UK"));
       for (TaskSummary summary: tasks){
             // ...
                org.jbpm.task.Task t = localTaskService.getTask(summary.getId());
             // ....
            }
        }
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Note that this code is annotated as @Transactional</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>If I call this code from a single thread or inside a synchronized block I have no problems.  If I call it from multiple concurrent threads, I consistently trigger the error:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>java.lang.IllegalStateException: Trying to return an unknown connection2! org.jboss.jca.adapters.jdbc.jdk6.WrappedConnectionJDK6@2a77a3c4</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>The trigger seems to be the inner call to the localTaskService.  With just the outer call I have no problems.  </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Googling this error, it seems this was a common problem with older hibernate versions (2.x) but I did not find any references to people seeing it for hibernate 4.x.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Any ideas?</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Thanks,</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Jon</p></div>
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<p style="margin: 0;">Reply to this message by <a href="https://community.jboss.org/message/817047#817047">going to Community</a></p>
<p style="margin: 0;">Start a new discussion in jBPM at <a href="https://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2034">Community</a></p>
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