Rest : An exception occurred in the persistence layer

Camunda 7 Topics Discussion & Questions
1

Hello,

It’s been for many days now that I am trying to execute an external task on camunda using python.
After creating a process with an external task with the topic as topicName as follows:

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I am trying to apply the fetch and lock post but I am getting an error. Here is the code and the error I am getting:

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org.camunda.bpm.engine.ProcessEngineException: An exception occurred in the persistence layer. Please check the server logs for a detailed message and the entire exception stack trace.
at org.camunda.bpm.engine.impl.util.ExceptionUtil.wrapPersistenceException(ExceptionUtil.java:263) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.util.ExceptionUtil.doWithExceptionWrapper(ExceptionUtil.java:257) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.db.sql.DbSqlSession.executeSelectList(DbSqlSession.java:111) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.db.sql.DbSqlSession.selectList(DbSqlSession.java:103) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.selectListWithRawParameter(DbEntityManager.java:182) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.selectList(DbEntityManager.java:174) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.persistence.entity.ExternalTaskManager.selectExternalTasksForTopics(ExternalTaskManager.java:95) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.cmd.FetchExternalTasksCmd.execute(FetchExternalTasksCmd.java:76) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.cmd.FetchExternalTasksCmd.execute(FetchExternalTasksCmd.java:46) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:28) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:110) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:72) ~[camunda-engine-spring-7.15.0.jar:7.15.0]
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140) ~[spring-tx-5.3.4.jar:5.3.4]
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:70) ~[camunda-engine-spring-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:70) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.interceptor.CommandCounterInterceptor.execute(CommandCounterInterceptor.java:35) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:33) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.impl.externaltask.ExternalTaskQueryTopicBuilderImpl.execute(ExternalTaskQueryTopicBuilderImpl.java:60) ~[camunda-engine-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.rest.impl.FetchAndLockHandlerImpl.executeFetchAndLock(FetchAndLockHandlerImpl.java:268) ~[camunda-engine-rest-jaxrs2-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.rest.impl.FetchAndLockHandlerImpl.tryFetchAndLock(FetchAndLockHandlerImpl.java:251) ~[camunda-engine-rest-jaxrs2-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.rest.impl.FetchAndLockHandlerImpl.addPendingRequest(FetchAndLockHandlerImpl.java:316) ~[camunda-engine-rest-jaxrs2-7.15.0.jar:7.15.0]
at org.camunda.bpm.engine.rest.impl.FetchAndLockRestServiceImpl.fetchAndLock(FetchAndLockRestServiceImpl.java:38) ~[camunda-engine-rest-jaxrs2-7.15.0.jar:7.15.0]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.lambda$static$0(ResourceMethodInvocationHandlerFactory.java:52) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:124) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:167) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$VoidOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:159) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:79) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:469) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:391) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:80) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:255) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:248) ~[jersey-common-2.32.jar:na]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:244) ~[jersey-common-2.32.jar:na]
at org.glassfish.jersey.internal.Errors.process(Errors.java:292) ~[jersey-common-2.32.jar:na]
at org.glassfish.jersey.internal.Errors.process(Errors.java:274) ~[jersey-common-2.32.jar:na]
at org.glassfish.jersey.internal.Errors.process(Errors.java:244) ~[jersey-common-2.32.jar:na]
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:265) ~[jersey-common-2.32.jar:na]
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:234) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:680) ~[jersey-server-2.32.jar:na]
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:394) ~[jersey-container-servlet-core-2.32.jar:na]
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:346) ~[jersey-container-servlet-core-2.32.jar:na]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:366) ~[jersey-container-servlet-core-2.32.jar:na]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:319) ~[jersey-container-servlet-core-2.32.jar:na]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:205) ~[jersey-container-servlet-core-2.32.jar:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.camunda.bpm.engine.rest.filter.CacheControlFilter.doFilter(CacheControlFilter.java:45) ~[camunda-engine-rest-jaxrs2-7.15.0.jar:7.15.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.camunda.bpm.engine.rest.filter.EmptyBodyFilter.doFilter(EmptyBodyFilter.java:99) ~[camunda-engine-rest-jaxrs2-7.15.0.jar:7.15.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.4.jar:5.3.4]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.4.jar:5.3.4]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.4.jar:5.3.4]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:346) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:887) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1684) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
at java.base/java.lang.Thread.run(Thread.java:831) ~[na:na]
Caused by: org.apache.ibatis.exceptions.PersistenceException:

Error querying database. Cause: org.apache.ibatis.builder.BuilderException: Error evaluating expression ‘parameter != null && parameter.topics.size > 0’. Cause: org.apache.ibatis.ognl.OgnlException: size [java.lang.reflect.InaccessibleObjectException: Unable to make public final int java.util.HashMap$Values.size() accessible: module java.base does not “opens java.util” to unnamed module @11758f2a]

2

Note that it is a spring boot project

3

This might be something that @Nele may be able to help with.

4

Yes definitely. I followed @Nele’s tutorial on Youtube and used her code. However I need this to work with a spring boot project which is unfortunately not the case … :confused:

5

Hey @Daaboul,

The good news: There is nothing wrong with the Python code. And there should be no problem with using this with a SpringBoot Project. I just tried it with the same code and it works for me.

So bad news: It looks like it comes from mybatis. Can you give more details about your SpringBoot application? Which Camunda version are you running and which version of JDK? And maybe which database?

Not 100% if I can further help but at least I can try to reproduce the error and try to find out, how to fix it.

Cheers
Nele

6

Thank you @Nele for the reply.

I generated a project using: https://start.camunda.com/ and kept all the fields as-is.

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Then, I ran the application and deployed the process shown above using camunda modeler. At this point, I run the python code and get the errors. (An exception occurred in the persistence layer…)

7

@Daaboul and which JDK version is installed on your machine?

8

C:\Users\abdallah.daaboul>java -version
java version “1.8.0_291”
Java™ SE Runtime Environment (build 1.8.0_291-b10)
Java HotSpot™ Client VM (build 25.291-b10, mixed mode, sharing)

9

You can find the code here:

10

Hey @Daaboul,

You are running your project on OpenJDK 16.0.1 . Now I get the same error as you do. Maybe the version of the JDK somehow interfere with mybatis and causes this error. I am not sure how to fix that quickly or what is needed to make this combination work.

The quick fix would be to exchange your JDK . I switched in your project to OpenJDK 14.0 and it works. So if you switch to a lower version of the JDK it should work.

I hope that helps
Kind regards
Nele

1 Like
11

Hey @Daaboul,

I can confirm that this is an issue with MyBatis on JDK16 and later, so switching to anything pre-JDK16 should fix it.

Regarding the issue itself, it will be fixed with https://jira.camunda.com/browse/CAM-13557.

Best,
Tobias

2 Likes
12

Thank you @Nele @tmetzke ,

This finally solved my problem.

Best Regards,
Abdallah