Bitbucket Self Hosted Runners V5 stopped scaling up in parallel steps

[Jesus Pena Mateos]

Hello,

We are currently experiencing an issue where our self-hosted Bitbucket runners are no longer autoscaling correctly when pipeline steps run in parallel.

Our setup consists of multiple runners on a physical machine, and we are in the process of migrating to EKS-based runners on AWS. The autoscaler controller version remains unchanged:

 bitbucketpipelines/runners-autoscaler:3.9.0

This setup was working correctly a few weeks ago. However, during the migration of some pipelines from the physical server, we noticed that parallel steps remain queued and only one step runs at a time.

After observing this behavior, we switched back to the (previously disabled) runners on the physical server. To our surprise, we found that the runner version had been automatically updated to v5, and the same parallelism issue appeared there as well.

Given that:

• the autoscaler controller version has not changed

• no new autoscaler releases have been published

• the issue started after the runners were upgraded to v5

we suspect either a regression or behavior change introduced in runner v5, or that an additional configuration change is now required.

Has anyone encountered a similar issue or knows if there are additional settings required for runner v5 to support parallel execution?

Thanks in advance for your help.