I came to work this morning with an inbox full of error reports because one of my maps was stuck at the 2/2 in use - starting at about 1am every available instance for that map became in use. I've run into this issue before, and I don't understand what the point of these timeout values are - while they do give control back to the calling application - it doesn't actually stop ArcGIS Server from continuing to process the request. So - if the person re-submits, that's the second one now in use.
I've also had a service in use for several weeks now - ArcGIS Server isn't properly recycling ones that become broken some how and the manager thinks they're in use.
Any way to fix this? This should not be something I have to manage.