OptimisticLockingException: ENGINE-03005 when starting a process trhough REST

Camunda 7 Topics Discussion & Questions
1

We’re interacting with camunda engine through the REST API and we’re getting periodic Optimistic Locking exceptions when starting the process. I’m not sure how this can happen, as I understand that starging a process is not a multi-thread operation.

This is the exception we got:

WARNING [http-nio-8080-exec-1] org.camunda.commons.logging.BaseLogger.logWarn ENGINE-REST-HTTP500 org.camunda.bpm.engine.rest.exception.RestException: Cannot instantiate process definition doacandidate:4:fa812260-ac0a-11ec-90a5-86637613f886: ENGINE-03005 Execution of 'UPDATE ExecutionEntity[2bb8f0fa-aa0d-11ec-8c18-621656be675d]' failed. Entity was updated by another transaction concurrently.
	at org.camunda.bpm.engine.rest.sub.repository.impl.ProcessDefinitionResourceImpl.startProcessInstance(ProcessDefinitionResourceImpl.java:131)
	at jdk.internal.reflect.GeneratedMethodAccessor1035.invoke(Unknown Source)

The Entity ID is not to be found in the database.

The process we try to start is similar to:

image
image1520×536 12.1 KB

It fails both when it goes towards subprocess 1 or subprocess 2.

We’re not using asynchronous continuations

Any idea on this?

2

Could you post the file that you’re using to reproduce?

Often the cause is a duplicated link between two elements (eg. between the “Process Started” and “Process” or betwen the unnamed start and “throw message”). If there’s a duplicated link, the tokens will be multiplied, so you’ll end up with things happening more often than you wanted.

3

There is no duplicated links that I can find, however the problem might be related to the fact of having 3 listeners on the start of the process that set the values of 3 variables:
image
Do you think this might be the root cause of the exception as this might have some concurrent updates in the database? If that is the case, is there a better way to initialize the variable values?

4

I wouldn’t think so, as they should be communicating with the execution engine, which then writes to the DB at the next async.

Are you able to reproduce it with a anonymous example process that you could then post?