Java.exe/javaw.exe Not terminating

When I open minecraft and enter a world or play multiplayer, the javaw.exe (or java.exe if I am on FTB/multiMC/Technic) does not terminate on close. I then try to got into the task manager and terminate it, to no avail. This only happens when I open Minecraft and get on a world, but when I just open then immediately close, it doesn't reproduce.