Programs are not usually started interactively on the HPC system, but rather sent as a job to a so-called resource manager, which is repsonsible for ensuring that a job is only started when the necessary resources are availble. Additionaly it uses a fairshare mechanism to control the start priorities of the jobs such that the resources are shared fairly.  If there are no free resources, then jobs belonging to a person who has not consumed many resources recently will be started beforethose of someone who has.

Note that comsuming resources affects the priority of your future jobs. However, it is not important what the job actually made use of, but simply the amount of resources which were requested, since these become unavailable to any other jobs.

The resource manager used on our systems is Slurm (Simple Linux Utility for Resource Management).