Locks sometimes block all the workers
It can happen that the job from `Queue().get_next_waiting_job()` is wrongly locked, which can make the workers fail to start a new job.

A way to fix this is to find a way to not have wrong locks or simply to ignore locked jobs in `Queue().get_next_waiting_job()`.
Locks sometimes block all the workers: It can happen that the job from `Queue().get_next_waiting_job()` is wrongly locked, which can make the workers fail to start a new job.

A way to fix this is to find a way to not have wrong locks or simply to ignore locked jobs in `Queue().get_next_waiting_job()`.