Triggering house cleaning events

What happens in the housecleaning process after the “Triggering house cleaning events” step?
We have a pulse hanging there for almost 30 mins now

The house cleaning event is fired and sent to the event sandbox for pulse. If this request takes too long, it should be timing out. Could you send us your Pulse logs from when this occured?

Sorry, just saw your response now. The logs are gone by now, but there was no error there, just simply the last line was “Triggering house cleaning events”. We killed the process eventually, and the next one starting up went through fine. Just wondering what may have caused this, to ensure it doesn’t happen again.