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LocalTaskService keep using one Entity Manager, Breaks when Database is Restarted
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created by <a href="https://community.jboss.org/people/thomas.setiabudi">Thomas Setiabudi</a> in <i>jBPM</i> - <a href="https://community.jboss.org/message/832416#832416">View the full discussion</a>
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<div class="jive-rendered-content"><p>Hi,</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>This is similar post to <a class="" href="https://community.jboss.org/thread/231488?tstart=0">https://community.jboss.org/thread/231488?tstart=0</a></p><p>Only that it discuss about LocalTaskService here</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I use JBPM5.4.Final, and Drools-Spring 5.4.Final in a Web Application.</p><p>I create Stateful Knowledge Session and LocalTaskService in the Spring config file, they are created once for the rest of the web application life.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Everything works fine, until the Database Server, MS SQL Server 2008, is restarted.</p><p>Which then break the Stateful Knowledge Session and LocalTaskService.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>After looking at the LocalTaskService code here<br/><a class="jive-link-external-small" href="https://github.com/droolsjbpm/jbpm/blob/5.4.x/jbpm-human-task/jbpm-human-task-core/src/main/java/org/jbpm/task/service/local/LocalTaskService.java#L52-L55">https://github.com/droolsjbpm/jbpm/blob/5.4.x/jbpm-human-task/jbpm-human-task-core/src/main/java/org/jbpm/task/service/local/LocalTaskService.java#L52-L55</a></p><p>Local Task Service has TaskServiceSession and then TaskServiceSession has TaskPersistenceManager which contain an EntityManager.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>The problem is this EntityManager is acquired from EntityManagerFactory just exactly once.</p><p>when the database connection is no longer valid (Because of Database Server restart), it will still use the same EntityManager which will of course throw exception.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>My question is, is it a bug? or I use these LocalTaskService Wrongly?</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Currently, to keep my application running, I create another class that implements TaskService, and have all the code just like LocalTaskService, the difference is I add a check before doing anything about the task.</p><p>This is a sample code:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>void</b></font> addTask(Task task, ContentData content) <font color="navy">{</font>
                    checkEntityManagerFactory();
                    session.addTask(task, content);
          <font color="navy">}</font>
 
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>and the checkEntityManagerFactory() implementation:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>void</b></font> checkEntityManagerFactory() <font color="navy">{</font>
                    <font color="navy"><b>if</b></font> (session != <font color="navy"><b>null</b></font>) <font color="navy">{</font>
                              <font color="navy"><b>try</b></font> <font color="navy">{</font>
                                        Query query = session.getTaskPersistenceManager()
                                                            .createNewQuery(<font color="red">"SELECT 1 FROM Task WHERE id = 0 "</font>);
                                        query.getResultList();
                              <font color="navy">}</font> <font color="navy"><b>catch</b></font> (Throwable e) <font color="navy">{</font>
                                        session = service.createSession();
                              <font color="navy">}</font>
 
 
                    <font color="navy">}</font> <font color="navy"><b>else</b></font> <font color="navy">{</font>
                              session = service.createSession();
                    <font color="navy">}</font>
          <font color="navy">}</font>
 
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>execute simple select query, when that query throws exception, that means its time to get new EntityManager which in this case is create new TaskServiceSession.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Is it the correct way to do this?</p><p>Will this issue fixed in JBPM 6 ?</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Any help is appreciated.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Regards,</p><p>Thomas Setiabudi</p></div>
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