Zeebe performance with a tree like connected workflows (parent-child relation)

Hi, we have a need to create workflow instances representing nodes in a tree like structure, so parent node waits for child workflows to be completed before doing some work(for example aggregating numbers up the hierarchy).

I tested with a simple workflow like below(with no external tasks etc to see pure zeebe performance) with a reasonable zeebe cluster(4 node, 12 partitions) and performance does not look good. i could be doing something wrong, hence checking.
15 levels, each node 2 children

above workflow which does not have any external jobs/tasks took nearly 1h to complete(and the cluster does not have any other activity/workflows going on), here is a screenshot from grafana dashboard.

we also observed that all the workflow instances are handled by the same partition, is it because of parent-child relation between these workflows? if so, it is concerning, is there a way to avoid this?

Hi @mrsateeshp :wave:

Thank you for raising this up.

Correct. The parent-child instances are all on the same partition to process them efficiently (i.e. without communicating to another partition that can be on a different node).

You could distribute the instances to other partitions by using message events or creating multiple process instances.

However, it is not expected that the processing of parent-child processes has a big overhead. Please share your examples to make it easy to reproduce the behavior.

Best regards,

Thanks Philipp.
may be a silly question, how to attach bpmn file here?
it is a very simple workflow to reproduce the behavior.

If it doesn’t work out-of-the-box in the forum then I recommend sharing a GitHub repository/gist that contains all required resources (e.g. processes, commands to send, etc.).

Steps to reproduce:

  1. deploy the following workflow: https://github.com/mrsateeshp/tmp/blob/main/Parent_Child_Wf_Testing.bpmn

  2. start a new workflow instance with payload {“input”: “1”} as shown below(does not require any job workers as there are no jobs in the workflow):

  3. it will create tree like connected workflows(15 levels), will take nearly 1hr to complete all the workflows(count 65535).

Thanks for sharing!

I ran the experiment on Camunda Cloud (Zeebe 1.0.0-rc1, Cluster size: 3, Partition size: 2, Replication size: 3). It took 13 minutes to complete all 65535 process instances.

So, that’s 84 process instances per second. And it uses only one partition (as described above).

I simplified the process a bit and removed some of the input mappings: Tree-like process execution (https://forum.camunda.io/t/zeebe-performance-with-a-tree-like-connected-workflows-parent-child-relation/2175) · GitHub

The numbers sound reasonable to me. I don’t see any bottlenecks. In order to tweak the performance, the execution could be distributed over more partitions (e.g. by using message events).

Does this make sense for you?

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