Docker runner concurrency stopped working

Hi,

I’ve set up a CI/CD pipeline with a runner using a docker image. The first stage of this pipeline has 2 jobs (unit-test and linter) that run in parallel. This pipeline has worked perfectly for 4 weeks.

Then one of the two jobs started failing randomly because of concurrency issues. When looking at the log, I see that the two jobs suddenly use the same concurrency number (always 0) for the runner:
Running on runner-nmsr1js--project-330-concurrent-0 via gitlab-srv
Previously, one of the jobs had concurrent-0 and the second one had concurrent-1

The runner config is quite simple, has not changed, and does not set any limit:

[[runners]]
[runners.docker]
image = "myimage"
privileged=true
disable_cache = false

I’ve tried to set a limit to the runner, global concurrency :

concurrent=6
[[runners]]
limit = 4
request_concurrency = 4
[runners.docker]
image = "myimage"
privileged=true
disable_cache = false

… without success

I am using a self-managed instance, version 14.6

Thanks for any suggestion that could help.
David

Found it…
The issue was that there was no more space on the disk, so I suppose that there was no way to create container-1
I think an error message, and a way to block the usage of runner container-0 by 2 jobs at the same time would have been better.