What can I do with stale processes that got left in the DSM?
These processes have to be removed.
First, check that the process is not active in the node by the Linux command 'ps -ef | grep nuo' check for the PID stale process from the "show domain summary".
Now that you confirmed that, you need to remove this process, this is how it is done:
nuodb [domain] > domainstate removeprocess $id
You may find more information and examples here.