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NullPointerException problem when console tried to start new sub process, triggered by signal sent from async task
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created by <a href="http://community.jboss.org/people/brucecui">Bruce Cui</a> in <i>jBPM</i> - <a href="http://community.jboss.org/message/613255#613255">View the full discussion</a>
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<div class="jive-rendered-content"><p>I know the subject is not quite clear. But problem itself does look that complex to me. </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Here is a background brief:</p><p>I tried to use jBPM to drive some backend batch processes, which basically requires multi-threading. After struggling with various problems, asking around in the forum, changing and rebuilding source codes, I finally came to this stage: the console can now pass ksession(actually kruntime) to my self-defined work item handlers, and I can trigger the event by calling ksession's signal method with return value to the processInstance.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>This was suppose to be a maybe not perfect, but at least a working solution. But problems just come after another. Now I found that once the process contains sub process, it would throw out NullPointerException at the point when trying to add the sub process to persistance: "org.jbpm.persistence.processinstance.JPAProcessInstanceManager.addProcessInstance(JPAProcessInstanceManager.java:37)".</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Another question is, I found that when I called the signalEvent method of the ksession, it actually took over the process and run the rest in this thread. So, say if I have a infinite loop, and an async task runs every round, and an signal event starts after it waiting for return event. If the task calls the signalEvent method every time, once a new thread takes over the process, will the old thread end? Or it will keep accumulating?</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Below is the log output of the first problem:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code">2011-07-04 19:13:01,092 INFO  [STDOUT] (Thread-107) kruntime: org.drools.impl.StatefulKnowledgeSessionImpl@7b2b39
2011-07-04 19:13:01,092 INFO  [STDOUT] (Thread-107) process: WorkflowProcessInstance8 [processId=com.xxxx.CustomerLoader,state=1]
2011-07-04 19:13:01,092 INFO  [STDOUT] (Thread-107) process instance id: 8
2011-07-04 19:13:01,092 INFO  [STDOUT] (Thread-107) File collector done. Signal out
2011-07-04 19:13:01,107 INFO  [STDOUT] (Thread-107) Collector Event Received
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107) Exception in thread "Thread-107"
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107) org.drools.RuntimeDroolsException: Unexpected exception executing action org.jbpm.process.instance.event.DefaultSignalManager$SignalProcessInstanceAction@c5ab84
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:996)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.drools.impl.StatefulKnowledgeSessionImpl.executeQueuedActions(StatefulKnowledgeSessionImpl.java:845)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.event.DefaultSignalManager.signalEvent(DefaultSignalManager.java:89)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.ProcessRuntimeImpl.signalEvent(ProcessRuntimeImpl.java:359)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.drools.impl.StatefulKnowledgeSessionImpl.signalEvent(StatefulKnowledgeSessionImpl.java:327)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at com.sample.FileCollector.run(FileCollector.java:74)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107) Caused by: java.lang.NullPointerException
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.persistence.processinstance.JPAProcessInstanceManager.addProcessInstance(JPAProcessInstanceManager.java:37)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.AbstractProcessInstanceFactory.createProcessInstance(AbstractProcessInstanceFactory.java:36)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:168)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.ProcessRuntimeImpl.createProcessInstance(ProcessRuntimeImpl.java:140)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:121)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.drools.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1095)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.drools.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:306)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.SubProcessNodeInstance.internalTrigger(SubProcessNodeInstance.java:121)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.SplitInstance.internalTrigger(SplitInstance.java:129)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.JoinInstance.triggerCompleted(JoinInstance.java:152)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.JoinInstance.internalTrigger(JoinInstance.java:52)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.SplitInstance.internalTrigger(SplitInstance.java:129)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.JoinInstance.triggerCompleted(JoinInstance.java:152)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.JoinInstance.internalTrigger(JoinInstance.java:52)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.ActionNodeInstance.triggerCompleted(ActionNodeInstance.java:55)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:51)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.ActionNodeInstance.triggerCompleted(ActionNodeInstance.java:55)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:51)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.EventNodeInstance.triggerCompleted(EventNodeInstance.java:66)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.node.EventNodeInstance.signalEvent(EventNodeInstance.java:50)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.signalEvent(WorkflowProcessInstanceImpl.java:353)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.jbpm.process.instance.event.DefaultSignalManager$SignalProcessInstanceAction.execute(DefaultSignalManager.java:117)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:994)
2011-07-04 19:13:01,138 ERROR [STDERR] (Thread-107)           ... 5 more
</code></pre></div>
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