Best practices to start multiples process instances

[Benjamin_Bellantonio]

Hi,

We are using Camunda in our software with the REST API.

From our software we are starting multiples process instances using Start Process Instance | docs.camunda.org

The problem is we can have sometimes hundreds of instances to start at the same time.
We didn’t find a way to start all theses instances without calling the API multiple times.

After a number of API calls Camunda is throwing some exceptions like :

Error querying database. Cause: org.apache.ibatis.transaction.TransactionException: Error configuring AutoCommit. Your driver may not support getAutoCommit() or setAutoCommit().

or

org.camunda.bpm.engine.rest.exception.RestException: Cannot instantiate process definition xxxxxxxxx:11:68a0f7a3-966e-11ea-92a3-ca1c9615904e: Process engine persistence exception
at org.camunda.bpm.engine.rest.sub.repository.impl.ProcessDefinitionResourceImpl.startProcessInstance(ProcessDefinitionResourceImpl.java:125)

Is there any good practices / advices to execute a batch process instances creation ?

Thanks in advance!

[aravindhrs]

@Benjamin_Bellantonio which database are you using?

Make sure db isolation is level been set to READ COMMITTED

Springboot starter - MySQL Isolation Level

@Jean_Robert_Alves you have to set it to globally to READ_COMMITTED as isolation level for MySQL. Camunda doesn’t change any of the db configurations. The Isolation level’s can be set globally or session based on our requirements. A change to global transaction characteristics requires the CONNECTION_ADMIN or SUPER privilege. Any session is free to change its session characteristics (even in the middle of a transaction), or the characteristics for its next transaction (prior to the sta…

[Benjamin_Bellantonio]

I am using MySQL, will update the configuration tomorrow if not like that. Do you have any advice for the multi start instances ? Or there is no other way to do it?

[Benjamin_Bellantonio]

DB isolation is correctly setup.

[aravindhrs]

@Benjamin_Bellantonio, to start multiple instances i would recommend to model multi instance subprocess, and pass the list input which will loop through and start multiple instances.

To configure the multi-instance activity, refer the below post:

Start the subprocess parallel with values from paraent workflow

Completion condition is optional, it means if completion condition is not given, then all the multi instances are expected to complete in-order to execute the next activity in the process, so still that execution token will waits in the multi-instance activity until all the instances completes. When the completion condition satisfies, and if few multi instances are still active, then those instances are deleted and the process continues to execute further activities in the process. for more d…

[Benjamin_Bellantonio]

Thanks for the reply, I thought about this solution but we are not planning to rework the BPMN entiererly to make it work in sub process.

In our system an instance is a single instance which modelize a single ‘Employee’ (even if there is subprocess also for this workflow).

Another solution could be to use JAVA api maybe to handle that case differently ?

[aravindhrs]

@Benjamin_Bellantonio, you can use Java API to perform bulk batch processing to start the instances.

And you can refer this solution also:

Question about correlateAll across multiple instances

Very interesting use case! The correlation seems to be doing what it is doing because its a single thread that is executing the correlation request and therefore its just 1 instances that does the correlation! Assuming there is not a api i am missing that would allow you do do some fancy job processing, You could do the following: Create a message query to find all process instances that match your variable query. This will create a array of process instances that you want to correlate agai…

[Benjamin_Bellantonio]

@aravindhrs

you can use Java API to perform bulk batch processing to start the instances.

Thanks a lot for your response, will have to find what is the best for us now

[Ingo_Richtsmeier]

Hi @Benjamin_Bellantonio,

the best way to start as many processes as possible is to include as less logic into the process before it is saved to the database for the first time…

The easiest way to reach that goal is mark every process model with Asynchronous before on the start event.

Hope this helps, Ingo