In ArcGIS Server, the geoprocessing services such as print services cause detached processes, leading to high memory usage.
The ArcGIS Server 10.8.1 Geoprocessing Service Orphaned Process Patch is live on the support site. The URL is: https://support.esri.com/en/download/7840.
This issue is fixed in ArcGIS Server 10.9 and in the ArcGIS Server 10.8.1 Geoprocessing Service Orphaned Process Patch which is available at https://support.esri.com/en/download/7840.