OptimisticLockException:‘DELETE ExternalTaskEntity[818ea893-6684-11e8-b666-fa163e5b9340]’ failed. Entity was updated by another transaction concurrently

Hi Experts,

During process execution we are getting the following error :
ENGINE-03005 Execution of ‘DELETE ExternalTaskEntity[818ea893-6eeb-11e8-b622-fa163e5b9340]’ failed. Entity was updated by another transaction concurrently.

Dur to the complexity of the process, we are not able to identify the location of the conflicting transactions in the process.

We enabled the following logs in the logback.xm.

org.camunda.bpm.engine.persistence
org.camunda.bpm.engine.cmd
org.camunda.bpm.engine.impl.persistence.entity.VariableInstanceEntity

and appended it like below in the logback.xml (Please refer the attached pic)

We got the “OptimisticLockException” after enabling these logs but nothing specific is logged in the catalina logs related to these OLE. am I doing any mistake while configuring the logs ?

Please advise how do we determine which 2 transactions are causing the locks ?

Thanks