I think there should be a small section in the Sys admin guide about setting nice-based priorities.
There may be support for this on two levels: Global and component-level. Mark Kelly can provide details when decided.
Related two pull requests for this:
1). https://github.com/hpcc-systems/HPCC-Platform/pull/11 per component-
2). https://github.com/hpcc-systems/HPCC-Platform/pull/11072 - global all hpcc components