NullPointerException on jobexecutor.TimerCatchIntermediateEventJobHandler

[galen...@gmail.com]

Hi,

I'm not sure if I'm getting a NullPointerExecption in the camunda code when I have a cycle with a timer. I saw this exception in a more complex flow, but I simplified it down to this:

http://camunda.org/share/#/process/cdb35790-3bf3-4201-bd4f-7f5f1d843688

It seems to cycle successfully for about 3 or 4 times, but it always ends up with the following failure (see stacktrace below). At first I thought this might be due to the same variable name being set, but I disabled the setting of variables, and the problem still happens.

NOTE: the timer is setup to fire every 30 seconds (at 0 seconds and 30 seconds after each minute)

Any ideas?

Thanks,
Galen

SEVERE: Error while closing command context
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.jobexecutor.TimerCatchIntermediateEventJobHandler.execute(TimerCatchIntermediateEventJobHandler.java:35)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:92)
at org.camunda.bpm.engine.impl.persistence.entity.TimerEntity.execute(TimerEntity.java:59)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:70)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd execute
SEVERE: Failure while executing org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd for job id '87'. Falling back to standard job retry strategy.
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable run
WARNING: Exception while executing job with id 87
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.jobexecutor.TimerCatchIntermediateEventJobHandler.execute(TimerCatchIntermediateEventJobHandler.java:35)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:92)
at org.camunda.bpm.engine.impl.persistence.entity.TimerEntity.execute(TimerEntity.java:59)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:70)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.interceptor.CommandContext close
SEVERE: Error while closing command context
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.jobexecutor.TimerCatchIntermediateEventJobHandler.execute(TimerCatchIntermediateEventJobHandler.java:35)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:92)
at org.camunda.bpm.engine.impl.persistence.entity.TimerEntity.execute(TimerEntity.java:59)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:70)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd execute
SEVERE: Failure while executing org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd for job id '87'. Falling back to standard job retry strategy.
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable run
WARNING: Exception while executing job with id 87
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.jobexecutor.TimerCatchIntermediateEventJobHandler.execute(TimerCatchIntermediateEventJobHandler.java:35)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:92)
at org.camunda.bpm.engine.impl.persistence.entity.TimerEntity.execute(TimerEntity.java:59)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:70)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.interceptor.CommandContext close
SEVERE: Error while closing command context
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.jobexecutor.TimerCatchIntermediateEventJobHandler.execute(TimerCatchIntermediateEventJobHandler.java:35)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:92)
at org.camunda.bpm.engine.impl.persistence.entity.TimerEntity.execute(TimerEntity.java:59)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:70)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd execute
SEVERE: Failure while executing org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd for job id '87'. Falling back to standard job retry strategy.
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.interceptor.CommandContext close
SEVERE: Error while closing command context
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.persistence.entity.IncidentEntity.setExecution(IncidentEntity.java:250)
at org.camunda.bpm.engine.impl.persistence.entity.IncidentEntity.createAndInsertIncident(IncidentEntity.java:111)
at org.camunda.bpm.engine.impl.incident.FailedJobIncidentHandler.handleIncident(FailedJobIncidentHandler.java:46)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.createFailedJobIncident(JobEntity.java:202)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.setRetries(JobEntity.java:181)
at org.camunda.bpm.engine.impl.cmd.DecrementJobRetriesCmd.execute(DecrementJobRetriesCmd.java:55)
at org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd.executeStandardStrategy(FoxJobRetryCmd.java:139)
at org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd.execute(FoxJobRetryCmd.java:49)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.FailedJobListener.execute(FailedJobListener.java:47)
at org.camunda.bpm.engine.spring.SpringTransactionContext$4.afterCompletion(SpringTransactionContext.java:84)
at org.springframework.transaction.support.TransactionSynchronizationUtils.invokeAfterCompletion(TransactionSynchronizationUtils.java:168)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.invokeAfterCompletion(AbstractPlatformTransactionManager.java:993)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.triggerAfterCompletion(AbstractPlatformTransactionManager.java:968)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(AbstractPlatformTransactionManager.java:872)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.rollback(AbstractPlatformTransactionManager.java:822)
at org.springframework.transaction.support.TransactionTemplate.rollbackOnException(TransactionTemplate.java:161)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:134)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
08:57:10,417 [pool-1-thread-3] ERROR org.springframework.transaction.support.TransactionSynchronizationUtils - TransactionSynchronization.afterCompletion threw exception
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.persistence.entity.IncidentEntity.setExecution(IncidentEntity.java:250)
at org.camunda.bpm.engine.impl.persistence.entity.IncidentEntity.createAndInsertIncident(IncidentEntity.java:111)
at org.camunda.bpm.engine.impl.incident.FailedJobIncidentHandler.handleIncident(FailedJobIncidentHandler.java:46)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.createFailedJobIncident(JobEntity.java:202)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.setRetries(JobEntity.java:181)
at org.camunda.bpm.engine.impl.cmd.DecrementJobRetriesCmd.execute(DecrementJobRetriesCmd.java:55)
at org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd.executeStandardStrategy(FoxJobRetryCmd.java:139)
at org.camunda.bpm.engine.impl.cmd.FoxJobRetryCmd.execute(FoxJobRetryCmd.java:49)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.FailedJobListener.execute(FailedJobListener.java:47)
at org.camunda.bpm.engine.spring.SpringTransactionContext$4.afterCompletion(SpringTransactionContext.java:84)
at org.springframework.transaction.support.TransactionSynchronizationUtils.invokeAfterCompletion(TransactionSynchronizationUtils.java:168)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.invokeAfterCompletion(AbstractPlatformTransactionManager.java:993)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.triggerAfterCompletion(AbstractPlatformTransactionManager.java:968)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(AbstractPlatformTransactionManager.java:872)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.rollback(AbstractPlatformTransactionManager.java:822)
at org.springframework.transaction.support.TransactionTemplate.rollbackOnException(TransactionTemplate.java:161)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:134)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Dec 6, 2013 8:57:10 AM org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable run
WARNING: Exception while executing job with id 87
java.lang.NullPointerException
at org.camunda.bpm.engine.impl.jobexecutor.TimerCatchIntermediateEventJobHandler.execute(TimerCatchIntermediateEventJobHandler.java:35)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:92)
at org.camunda.bpm.engine.impl.persistence.entity.TimerEntity.execute(TimerEntity.java:59)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:70)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:79)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:67)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)

[Daniel Meyer]

Hi Galen,

do you think you could maybe provide a failing testcase? If not, we will
try to reproduce it next week.

Cheers,
Daniel Meyer

[galen...@gmail.com]

Hi Daniel,

Here is my test case:

@Deployment(resources = { "org/camunda/bpm/engine/test/bpmn/event/timer/cam_cycle.bpmn"})
public void testTimerCycle() throws Exception {
try {
// Start process
//
String instanceId = runtimeService.startProcessInstanceByKey("cam_cycle").getProcessInstanceId();

// Wait for process to run to completion...
//
while (true) {
ProcessInstance processInstance =
runtimeService.createProcessInstanceQuery()
.processInstanceId(instanceId).singleResult();
if (processInstance == null) {
log.info("PROCESS ["+instanceId+"] DOES NOT EXIST ANYMORE");
break;
}
else if (processInstance.isEnded()) {
log.info("PROCESS ["+instanceId+"] ENDED");
break;
}
else {
log.info("PROCESS["+processInstance.getProcessInstanceId()+"] (suspended="+processInstance.isSuspended()+", ended="+processInstance.isEnded()+")");
}
try {
Thread.sleep(1000);
ClockUtil.setCurrentTime(new Date(ClockUtil.getCurrentTime().getTime() + 1000));
log.info("CURRENT TIME IS: "+ClockUtil.getCurrentTime());
} catch (InterruptedException e) { ; }
}
} catch (ProcessEngineException e) {
assertTextPresent("Unknown property used in expression", e.getMessage());
}

}

++++++++++++++++++++++++++++++++++++++++++++++++++++++++

But for some reason (even though the Clock is proceeding, the timer catch event never seems to fire. It's probably due to something I'm not understanding in the test framework. I added the above method to the TimeExpressionTest.java class.

Here is my BPMN:

<?xml version="1.0" encoding="UTF-8"?>
<bpmn2:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:camunda="http://activiti.org/bpmn" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd" id="_Qog-UF6VEeO4H9y8BRwdzw" targetNamespace="http://activiti.org/bpmn">
<bpmn2:process id="cam_cycle" isExecutable="true">
<bpmn2:scriptTask id="ScriptTask_1" name="log a message" scriptFormat="JavaScript">
<bpmn2:incoming>SequenceFlow_4</bpmn2:incoming>
<bpmn2:incoming>SequenceFlow_6</bpmn2:incoming>
<bpmn2:outgoing>SequenceFlow_5</bpmn2:outgoing>
<bpmn2:script>java.lang.System.out.println('script task executing');</bpmn2:script>
</bpmn2:scriptTask>
<bpmn2:sequenceFlow id="SequenceFlow_5" name="" sourceRef="ScriptTask_1" targetRef="IntermediateCatchEvent_1"/>
<bpmn2:intermediateCatchEvent id="IntermediateCatchEvent_1">
<bpmn2:incoming>SequenceFlow_5</bpmn2:incoming>
<bpmn2:outgoing>SequenceFlow_6</bpmn2:outgoing>
<bpmn2:timerEventDefinition id="_TimerEventDefinition_2">
<bpmn2:timeCycle xsi:type="bpmn2:tFormalExpression">0,30 * * * * ?</bpmn2:timeCycle>
</bpmn2:timerEventDefinition>
</bpmn2:intermediateCatchEvent>
<bpmn2:sequenceFlow id="SequenceFlow_6" name="" sourceRef="IntermediateCatchEvent_1" targetRef="ScriptTask_1"/>
<bpmn2:startEvent id="StartEvent_1">
<bpmn2:outgoing>SequenceFlow_4</bpmn2:outgoing>
</bpmn2:startEvent>
<bpmn2:sequenceFlow id="SequenceFlow_4" name="" sourceRef="StartEvent_1" targetRef="ScriptTask_1"/>
</bpmn2:process>
</bpmn2:definitions>

[Daniel Meyer]

Hi Galen,

we just had a look at your process:

The problem is that you use a timeCycle definition for providing the time format. This leads to a cycling behavior causing each instance of the intermediate timer event to fire an infinite number of times.

The following expression means:

<bpmn2:timeCycle xsi:type="bpmn2:tFormalExpression">0,30 * * * * ?</bpmn2:timeCycle>

every 30 seconds (at 0 seconds and 30 seconds after each minute) UNTIL THE END OF TIMES

As a result, when the first timer fires, it will not delete itself but it will stay active and fire again. So after the first timer has fired, you will end up with 2 timer jobs in the database: one for the second loop instance (OK) and one for the first loop instance (BAD, since it re-created itself). The corresponding execution will not exist any more hence the NullPointerExecption you are experiencing. 

You can fix your testcase using the following code:

  <bpmn2:intermediateCatchEvent id="IntermediateCatchEvent_1">

      <bpmn2:incoming>SequenceFlow_5</bpmn2:incoming>

      <bpmn2:outgoing>SequenceFlow_6</bpmn2:outgoing>

      <bpmn2:timerEventDefinition id="_TimerEventDefinition_2">

        <bpmn2:timeDuration xsi:type="bpmn2:tFormalExpression">PT30S</bpmn2:timeDuration>

      </bpmn2:timerEventDefinition>

    </bpmn2:intermediateCatchEvent>

So I think that actually <timeCycle> makes no sense in combination with the intermediate timer event: as this one should only fire once, leave the event and not fire again. It should only fire again if the event is entered a second time (as in your example) and then a new instance of the timer should be created. 

I think that the parser should reject the <timeCycle> for the following BPMN constructs:

- intermediate timer event

- interrupting boundary event

- start event for interrupting event subprocess. 

We should give this some more thought and also have a look at the BPMN specification.

Cheers,

Daniel

[galen...@gmail.com]

Hi Daniel,

Thanks for clarifying this behavior. However, I was just using "every 30 seconds" as a simple test to verify behaviour before I changed it to "every midnight" (the real use case). For my use case it's preferable to NOT use a duration, but to have a CRON-formatted specific time. In other words, I don't always know how much time the task after the timer will take. So I can't simply say for example that it will take 30 seconds, and therefore I will perform a duration of 23 hours, 59 minutes, and 30 seconds.

I have a feeling there's a better way to architect this BPMN, and I'm just not doing it correctly. Any feedback on how to do this without using "timeDuration" would be awesome.

What I want to do is similar in concept to Figure 123 on page 203 of this link:
http://www.omg.org/bpmn/Documents/BPMN_Section_7.pdf

I think they must also be using some sort of scheduling semantics, rather than a duration, since they specify "Friday at 6 pm".

Thanks,
Galen

[rwba...@gmail.com]

I am experiencing this same issue (using <timeCycle>0/30 * * * * ?</timeCycle>) and am curious if a fix for this use-case exists?

Thanks,
Ron

[Daniel Meyer]

Hi Ron,

Are you using an intermediate catch event or a different kind of event?

You cannot use TimeCycles with intermediate catch events because an intermediate event can only fire *once*. So there can be no cycle.

Time cycles work with other events like non-interrupting boundary events.

Does this help you?

Cheers,

Daniel

[rwba...@gmail.com]

Hi Daniel,

Yes, I am trying to use an intermediate catch event to implement a timer that fires every hour. If I can't use an intermediate catch event, do you have a suggestion on implementing an hourly trigger?

Thanks,
Ron

[webcyberrob]

Hi Ron,

Some patterns I tend to use:

If this is a reminder that some task has not been performed within SLA, the I use a non-interrupting boundary event timer on the task. As a common example, often I use asynchronous request/response services. Hence on my receive task, I use the non-interrupting boundary event timer to trigger reminders. In addition, I use a principle that I have an interrupting boundary event timer configured with a conservative timeout. The intent here is if it fires, the process is considered abandoned. The rationale is to ensure that the engine does not get clogged with abandoned processes.

Rob