Hi @Andres.Aulasneo, thanks for the tip.
We are currently working on moving dbs to another server, and in the mid-term to Kubernetes.
Now the workers are killed after 5 minutes of being busy and we have 16 lms workers, the LMS is not blocked anymore. But there are some functionality like sending password reset email that are not working: the uwsgi keeps waiting for mysql to answer and the worker keeps busy until it is killed.
I don’t know if k8s or separating the db will help on this problem, as it is somehow linked with user’s data and emails, not necessarily with platform performance. I’ve created this issue Error sending bulk emails - Site Operators / Tutor Help - Open edX discussions where I explain some more on this subject.
Many thanks for all your help