[jBPM] - NullPointerException problem when console tried to start new sub process, triggered by signal sent from async task
6:47 a.m.
Bruce Cui [http://community.jboss.org/people/brucecui] created the discussion
"NullPointerException problem when console tried to start new sub process, triggered
by signal sent from async task"
To view the discussion, visit: http://community.jboss.org/message/613255#613255
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I know the subject is not quite clear. But problem itself does look that complex to me.
Here is a background brief:
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.
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)".
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?
Below is the log output of the first problem:
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
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10:03 p.m.
New subject: [jBPM] - Re: NullPointerException problem when console tried to start new sub process, triggered by signal sent from async task
Kris Verlaenen [http://community.jboss.org/people/KrisVerlaenen] created the discussion
"Re: NullPointerException problem when console tried to start new sub process,
triggered by signal sent from async task"
To view the discussion, visit: http://community.jboss.org/message/613357#613357
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Hi,
It seems your FileCollector is directly accessing the internal session. Note however,
when using persistence, we actually wrap this internal session with a command service
(SingleSessionCommandService) that takes care of persistence etc. This seems to be an
issue where you're getting issues by directly accessing the internal session,
bypassing persistence setup etc.
You should not talk to the internal session directly, your client calls should always go
through the command service, using the ksession you get when using the JPAKnowledgeService
to construct the session.
Not sure if I understand your second issue. The engine typically uses the calling thread
to execute. So if you call signalEvent, that thread will be used to send the event and
execute the any process instance that is triggered because of this. But this thread will
return as soon as processing is done. So this is either immediate (when there is no-one
interested in the event) or after the process instance has reached a wait state (which
again is almost instantaneous, as anything that is not should be modeled as an async task
anyway).
Kris
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10:07 p.m.
New subject: [jBPM] - Re: NullPointerException problem when console tried to start new sub process, triggered by signal sent from async task
Bruce Cui [http://community.jboss.org/people/brucecui] created the discussion
"Re: NullPointerException problem when console tried to start new sub process,
triggered by signal sent from async task"
To view the discussion, visit: http://community.jboss.org/message/613363#613363
--------------------------------------------------------------
Hi Kris,
Thanks a lot for the clarification. I am using the ksession which is injected when the
WorkItemManager registers the handler. I'll keep digging on the direction you showed
me. But last change took me almost a whole weekend. If you could help with the code change
this time that would be great. Plz let me know if I need to open a JIRA for that. Or, as
long as the console could keep functioning, if there is a way to turn off JPA that would
be a secondary option for me, since for now persistence is not a necessary feature for my
needs.
And for the second question, I think you've answered it even with my poor expression.
So if I undersatnd right, even the process is defined as an infinite loop, if in the loop
it calls an async task first and then comes to a wait state by a signal event node, the
thread will return, and the rest of the loops will be handed to the next signalEvent
caller thread, and so goes on. The reason I asked this was becasue I worried about if the
old threads didn't return, there would be more and more threads accumulated in similar
scenario and finally ate up all resources. But if it works in the way you explained, there
should be no problem.
Bruce
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participants (2)
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Bruce Cui -
Kris Verlaenen