Unexpected App Shutdown in Background

I am testing a number of apps that do valid things in the background for extended periods of time. Since the 9.0 update I am seeing unexpected app shutdown occuring for all of these at about the same time. No clue as to why.


I can look at log files generated by each, and all is going well. THe phone is locked and stationary. After an hour or so, each of the apps will terminate at about the same time. Someimes its an hour, sometimes multiple hours.


Any ideas?