Hi,

on various occasions we have observed the following phenomenon. We get an optimistic locking exception in a process, like such:

{{27-Sep-2017 03:24:18.684 WARNING [pool-2-thread-204] org.camunda.commons.logging.BaseLogger.logWarn ENGINE-14006 Exception while executing job 13aedcdb-a31f-11e7-b8c1-00505687ba57:
org.camunda.bpm.engine.OptimisticLockingException: ENGINE-03005 Execution of 'DELETE MessageEntity[13aedcdb-a31f-11e7-b8c1-00505687ba57]' failed. Entity was updated by another transaction concurrently.
at org.camunda.bpm.engine.impl.db.EnginePersistenceLogger.concurrentUpdateDbEntityException(EnginePersistenceLogger.java:125)
at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.handleOptimisticLockingException(DbEntityManager.java:342)
at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flushDbOperationManager(DbEntityManager.java:308)
at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flush(DbEntityManager.java:281)
at org.camunda.bpm.engine.impl.interceptor.CommandContext.flushSessions(CommandContext.java:203)
at org.camunda.bpm.engine.impl.interceptor.CommandContext.close(CommandContext.java:132)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:113)
at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:66)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:30)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:36)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:29)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:88)
at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:57)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)}}

This exact same message (same job id) will then repeat several times a second, sometime until the offending process is manually cancelled.

We are not able to replicate this behavior intentionally.

We are wondering is there a) an obvious reason for such a behavior that we might resolve, or b) is there a way to collect more data when this occurs that would allow you to give a more thorough analysis.

Many thanks in advance.