Classloading issue after Timer Intermediate Catching Event

Ramya · July 26, 2019, 7:02am

Hi Everyone,

I have created a simple process with two service tasks and added java class in service tasks.

It worked fine and when i added a ‘Timer Intermediate Catching Event’ in between service tasks as shown, when a process instance is invoked it’s failing “Cannot load class” for the java class defined in service task2. Please suggest.

Below is the detailed error.

Caused by: org.camunda.bpm.engine.ClassLoadingException: ENGINE-09017 Cannot load class ‘com.example.camunda.TestClass2’: com.example.camunda.TestClass2
at org.camunda.bpm.engine.impl.util.EngineUtilLogger.classLoadingException(EngineUtilLogger.java:138)
at org.camunda.bpm.engine.impl.util.ReflectUtil.loadClass(ReflectUtil.java:110)
at org.camunda.bpm.engine.impl.util.ClassDelegateUtil.instantiateDelegate(ClassDelegateUtil.java:45)
… 134 more
Caused by: java.lang.ClassNotFoundException: com.example.camunda.TestClass2
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:471)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at com.liferay.portal.module.framework.ModuleFrameworkClassLoader.loadClass(ModuleFrameworkClassLoader.java:98)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at org.eclipse.osgi.internal.framework.ContextFinder.loadClass(ContextFinder.java:132)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:398)
at org.camunda.bpm.engine.impl.util.ReflectUtil.loadClass(ReflectUtil.java:87)
… 135 more

Niall · July 26, 2019, 7:11am

What is your setup like?
Application server?
Version of Camunda?
Are you using a cluster or a single node?
How are you deploying your process (WAR file or REST API)?

Ramya · July 26, 2019, 7:29am

Camunda 7.10 Embedded server as WAR, single node.

Niall · July 26, 2019, 7:30am

Can you expand on that a bit?

Ramya · July 26, 2019, 7:41am

i have configured camunda following below link as spring based embedded process engine.

https://docs.camunda.org/get-started/spring/embedded-process-engine/

Niall · July 26, 2019, 7:42am

Gotcha! Can you upload your model?

Ramya · July 26, 2019, 7:44am

Test_Timer.bpmn (4.2 KB)

Niall · July 26, 2019, 7:47am

So that does look, the only issue would be if the path to java class is wrong.
Can you double check the path and the class name of your second java class?

Ramya · July 26, 2019, 7:53am

i have checked no issues with that, also if i remove the timer, it works fine.

Niall · July 26, 2019, 7:56am

So that would mean the job executor is picking up the thread after the timer has fired and the class is not in the path. This can happen in a cluster if a node does not have the class referenced in the BPMN model. But it shouldn’t really happen on a single node setup.

I’m going to need to try to re-produce this issue. I’ll let you know if i find something

Ramya · July 26, 2019, 8:02am

FYI, i kept a logger after process instance is invoked. In normal case(without timer), Log is written after both the service tasks are executed. However in case of timer, logger is written immediately after timer is called and its not waiting for completion for timer duration and service task2 execution. After the timer waits for 1 min prescribed duration, it is failing up as class loader error.

srinivasreddy.java · February 11, 2020, 10:46am

Hi, Is there any solution found around this. We are facing the similar situation of classNotFoundExceptions.
The following details could be important for analysis

We are using camunda as OSGI bundle and an instance of Process Engine is created during the bundle startup.
The Java delegate and Camunda share the same class loader in OSGI.

Still we have issues with the Timer. We have seen that the same delegate gets executed before the timer but not after the timer.

Appreciate any help around this topic

org.camunda.bpm.engine.ProcessEngineException: ENGINE-09008 Exception while instantiating class ‘com.example.delegate.EmptyDelegate’: ENGINE-09017 Cannot load class ‘com.example.delegate.EmptyDelegate’: com.example.delegate.EmptyDelegate
at org.camunda.bpm.engine.impl.util.EngineUtilLogger.exceptionWhileInstantiatingClass(EngineUtilLogger.java:81)
at org.camunda.bpm.engine.impl.util.ClassDelegateUtil.instantiateDelegate(ClassDelegateUtil.java:53)
at org.camunda.bpm.engine.impl.bpmn.behavior.ClassDelegateActivityBehavior.getActivityBehaviorInstance(ClassDelegateActivityBehavior.java:111)
at org.camunda.bpm.engine.impl.bpmn.behavior.ClassDelegateActivityBehavior$1.call(ClassDelegateActivityBehavior.java:67)
at org.camunda.bpm.engine.impl.bpmn.behavior.ClassDelegateActivityBehavior$1.call(ClassDelegateActivityBehavior.java:64)
at org.camunda.bpm.engine.impl.bpmn.behavior.AbstractBpmnActivityBehavior.executeWithErrorPropagation(AbstractBpmnActivityBehavior.java:110)
at org.camunda.bpm.engine.impl.bpmn.behavior.ClassDelegateActivityBehavior.execute(ClassDelegateActivityBehavior.java:64)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute$2.callback(PvmAtomicOperationActivityExecute.java:60)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute$2.callback(PvmAtomicOperationActivityExecute.java:49)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.continueIfExecutionDoesNotAffectNextOperation(PvmExecutionImpl.java:1988)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute.execute(PvmAtomicOperationActivityExecute.java:41)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute.execute(PvmAtomicOperationActivityExecute.java:30)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:95)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:127)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:107)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:82)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:640)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:614)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl$6.callback(PvmExecutionImpl.java:1927)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl$6.callback(PvmExecutionImpl.java:1924)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.continueExecutionIfNotCanceled(PvmExecutionImpl.java:1994)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.dispatchDelayedEventsAndPerformOperation(PvmExecutionImpl.java:1943)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.dispatchDelayedEventsAndPerformOperation(PvmExecutionImpl.java:1924)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationTransitionNotifyListenerStart.eventNotificationsCompleted(PvmAtomicOperationTransitionNotifyListenerStart.java:60)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationTransitionNotifyListenerStart.eventNotificationsCompleted(PvmAtomicOperationTransitionNotifyListenerStart.java:30)
at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:67)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:95)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:127)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:107)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:82)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:72)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperationSync(ExecutionEntity.java:649)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperationSync(ExecutionEntity.java:624)
at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:60)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:95)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:127)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:107)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:82)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:72)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperationSync(ExecutionEntity.java:649)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperationSync(ExecutionEntity.java:624)
at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:60)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:95)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:127)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:107)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:82)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:640)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:614)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationTransitionCreateScope.scopeCreated(PvmAtomicOperationTransitionCreateScope.java:37)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationCreateScope.execute(PvmAtomicOperationCreateScope.java:53)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationCreateScope.execute(PvmAtomicOperationCreateScope.java:27)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:95)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:127)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:114)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:82)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:72)
at org.camunda.bpm.engine.impl.jobexecutor.AsyncContinuationJobHandler.execute(AsyncContinuationJobHandler.java:80)
at org.camunda.bpm.engine.impl.jobexecutor.AsyncContinuationJobHandler.execute(AsyncContinuationJobHandler.java:39)
at org.camunda.bpm.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:138)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:102)
at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:39)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:27)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:106)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:45)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:43)
at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:69)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:50)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:43)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:91)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:60)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.camunda.bpm.engine.ClassLoadingException: ENGINE-09017 Cannot load class ‘com.example.delegate.EmptyDelegate’:
com.example.delegate.EmptyDelegate
at org.camunda.bpm.engine.impl.util.EngineUtilLogger.classLoadingException(EngineUtilLogger.java:138)
at org.camunda.bpm.engine.impl.util.ReflectUtil.loadClass(ReflectUtil.java:110)
at org.camunda.bpm.engine.impl.util.ClassDelegateUtil.instantiateDelegate(ClassDelegateUtil.java:45)
… 73 more
Caused by: java.lang.ClassNotFoundException: com.example…delegate.EmptyDelegate
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

srinivasreddy.java · February 11, 2020, 4:36pm

We have solved this issue. We have set the same classloader of the bundle to the ProcessEngine through processEngineConfiguration.

processEngineConfiguration.setClassLoader(ClassLoaderUtil.getClassLoader()).
We were running the bundles in the Liferay enviroment. So we had the chance to use the ClassLoaderUtil.

Hope this helps.

Thanks

system · January 30, 2024, 11:51am