Since I upgraded to Yosemite, the applications on the dock stop running very often (no dot beside them), and in order to open them they have to relaunch. This happens with safari all the time and some of the other ones as well.
iMac (24-inch Early 2009), Other OS
Please post an EtreCheck report http://www.etresoft.com/etrecheck
Automatic and Sudden Termination of Apps
Automatic app termination manages the life cycle of apps behind the scenes, terminating apps that are not being used and allowing the reclamation of resources such as memory. With this feature, users no longer need to explicitly quit apps (although they still can, if they want to). Instead, the operating system is responsible for managing app processes with the goal of ensuring optimal system performance.
That makes sense, the problem is it happens a lot more than with previous software and it's slow to relaunch the app.
My request for an EtreCheck report was mostly to see how much ram you have. It sounds like OS X is shutting down unused apps because you don't have enough ram.
Dock applications stop running (no dot) since upgrading to yosemite
