Hi @AliceWilson,
Pkill.exe is an executable included with Portal for ArcGIS that is used to stop processes by their PIDs. There are a variety of reasons this process runs:
- A process gets hung with no activity for a specific length of time (this will vary with the process) the pkill will be invoked.
- If an illegal activity occurs in a process, pkill can be invoked to protect data.
- A process can call up pkill when it is completed.
Quarantining this executable may cause a degradation in Portal for ArcGIS' regular performance.