Error when trying to create concurrent jbpm process instance

[alagar_a]

Hi,

I am creating a web application where I am encountering an issue. I have given as much as details explaining the problem.

Components:

jboss-as-7.1.1.Final for webserver

jbpm-6.0.0.Final for BPMN management

postgres-9.1 database for persistence.

UI (created in HTML/Javascript) has list of fields for getting user input in a form. On submission of this form, calls rest API service implemented in java and these rest API services are deployed in jboss.  Jbpm war is deployed in jboss. Workflow BPMN diagram is created with eclipse jbpm plug-in editor and deployed in jboss.  We have configured jboss to use postgresql for persistence.

Every submission of the form creates a new instance of JBPM process for BPMN workflow defined.  The issue that we face is when more than one user is submitting the form at the same time,  the second call fails when trying to create JPMN process instance.

Few code snippets for reference:

We are using application scoped RuntimeEnvironment.

<snip>

    @Produces

    @Singleton

    public RuntimeEnvironment produceEnvironment(EntityManagerFactory emf, GlobalSchedulerService globalScheduler) {

        runtimeEnvironment = RuntimeEnvironmentBuilder

                .getDefault()

                .entityManagerFactory(emf)

                .userGroupCallback(usergroupCallback)

                .registerableItemsFactory(factory)

                .addAsset(

                        ResourceFactory

                                .newClassPathResource("workflow.bpmn"),  // workflow.bpmn is BPMN file.

                        ResourceType.BPMN2)

                .get();

    returnruntimeEnvironment;

</snip>

We have Bean managed Transaction so that we have our own transaction boundaries.

<snip>

@Startup

@javax.ejb.Singleton

@ConcurrencyManagement(ConcurrencyManagementType.BEAN)

@TransactionManagement(TransactionManagementType.BEAN)

public class ourBean {

@Inject

@Singleton

private RuntimeManager singletonManager;

    @Resource

    private UserTransaction userTransaction;

</snip>

Code for creating new process instance in jbpm.

<snip>

userTransaction.begin();

try {

RuntimeEngine runtimeengine = singletonManager.getRuntimeEngine(EmptyContext.get());

KieSession session = runtimeengine.getKieSession();

JPAWorkingMemoryDbLogger logger = new JPAWorkingMemoryDbLogger(session);

ProcessInstance processinstance=session.startProcess("workflow.bpmn.id", input);   //workflow.bpmn.id is id in BPMN file 

jbpm_instance_id = processinstance.getId();    

userTransaction.commit();

}

</snip>

When more than one user tries to submit form, we are getting the following error in jboss log.  [creation of second instance of jbpm process fails]

I am getting following exception:

12:43:39,829 ERROR [stderr] (http--127.0.0.1-8080-5) java.lang.RuntimeException: Process instance 1185[workflow.bpmn.id] is disconnected.

12:43:39,830 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.process.instance.impl.ProcessInstanceImpl.getProcess(ProcessInstanceImpl.java:90)

12:43:39,830 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.process.instance.impl.ProcessInstanceImpl.getContextInstance(ProcessInstanceImpl.java:161)

12:43:39,830 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.workflow.instance.WorkflowRuntimeException.initialize(WorkflowRuntimeException.java:56)

12:43:39,830 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.workflow.instance.WorkflowRuntimeException.<init>(WorkflowRuntimeException.java:42)

12:43:39,831 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:161)

12:43:39,831 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.ruleflow.instance.RuleFlowProcessInstance.internalStart(RuleFlowProcessInstance.java:35)

12:43:39,831 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.process.instance.impl.ProcessInstanceImpl.start(ProcessInstanceImpl.java:222)

12:43:39,831 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.start(WorkflowProcessInstanceImpl.java:358)

12:43:39,832 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcessInstance(ProcessRuntimeImpl.java:189)

12:43:39,832 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:171)

12:43:39,832 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1581)

12:43:39,832 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:366)

12:43:39,832 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.command.runtime.process.StartProcessCommand.execute(StartProcessCommand.java:121)

12:43:39,833 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.command.runtime.process.StartProcessCommand.execute(StartProcessCommand.java:40)

12:43:39,833 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.command.impl.DefaultCommandService.execute(DefaultCommandService.java:36)

12:43:39,833 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41)

12:43:39,833 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.persistence.SingleSessionCommandService$TransactionInterceptor.execute(SingleSessionCommandService.java:532)

12:43:39,834 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41)

12:43:39,834 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.persistence.jpa.OptimisticLockRetryInterceptor.execute(OptimisticLockRetryInterceptor.java:71)

12:43:39,834 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.persistence.SingleSessionCommandService.execute(SingleSessionCommandService.java:374)

12:43:39,834 ERROR [stderr] (http--127.0.0.1-8080-5)    at org.drools.core.command.impl.CommandBasedStatefulKnowledgeSession.startProcess(CommandBasedStatefulKnowledgeSession.java:232)

Following code in src/main/java/org/jbpm/process/instance/impl/ProcessInstanceImpl.java jbpm source code is throwing the error.

<snip>

    public Process getProcess() {

        if (this.process == null) {

                if (processXml == null) {

                        if (kruntime == null) {

                                throw new RuntimeException("Process instance " + id + "[" + processId + "] is disconnected.");

                        }

                        this.process = kruntime.getKieBase().getProcess(processId);

                } else {

                XmlProcessDumper dumper = XmlProcessDumperFactory.newXmlProcessDumperFactory();

                        this.process = dumper.readProcess(processXml);

                }

        }

        return this.process;

    }

</snip>

we are not able to find the root cause of this issue. Any pointers for resolving this would be very helpful. Please let me know for any further information.

[jay.guidos-bidstrading.com]

Hi there,

I am having exactly the same issue.  I believe there is a bug in 6.0.0 and 6.0.1 when two different transactions are opened against the same KieSession.  I have been discussing this issue with the JBPM folks, I will make sure they see your issue as well as mine.

FWIW, as long as you are not trying to modify the process itself from two different transactions, a temporary work around is presented in 6.0.1.Final transaction completion bug.  Again, to be clear, this is an appropriate temporary patch if ONLY you are not trying to modify the process instance from two different transactions.  Hopefully the main issue will be addressed soon.

Jay Guidos

[alagar_a]

Hi Jay,

thanks for the help and info.

We were able to get rid of this issue by commenting out 'kruntime=null' in ProcessInstanceImpl.java

public void disconnect() { 

        ((InternalProcessRuntime) kruntime.getProcessRuntime()).getProcessInstanceManager().internalRemoveProcessInstance(this); 

        process = null; 

//        kruntime = null; 

    }

We are not sure if this would create problem elsewhere. But just thought of posting this in forum.

thanks,

alagar

[swiderski.maciej]

the main issue here is the usage of singleton strategy with CMT/BMT (in general transaction that is managed outside of jbpm engine). There is a need to lock ksession to ensure it won't let any other thread to access it before transaction completion. Or do not use CMT/BMT and let jbpm engine to deal with transactions.

We are working to provide transaction locking capabilities out of the box and hopefully will be available in next release.

HTH

[joao.pereira]

Hi,

We have the same issue with 6.1.0.RC. We basically are using JMS to start a process, if we start one, it-s ok, however starting more than one at the same time, we get the "Process instance is disconnected". Has this been fixed? How can I have it fixed? If no two processes can be started at same time, is kind of useless.

Thanks

[swiderski.maciej]

you can enable transaction lock interceptor to achieve isolated processing with system property:

-Dorg.kie.tx.lock.enabled=true

HTH

[lauradp]

Hi,

can I configure this property by adding these lines in standalone-full.xml:

...

</extensions>

<system-properties>

        <property name="org.kie.tx.lock.enabled" value="true"/>

</system-properties>

<management>

...

Laura

[swiderski.maciej]

yes, it's completely valid to define system properties in standalone.xml

HTH