It is handling that internally. "As SharedPreferences instances are singletons within a process, it's safe to replace any instance of commit() with apply() if you were already ignoring the return value.
You don't need to worry about Android component lifecycles and their interaction with apply() writing to disk. The framework makes sure in-flight disk writes from apply() complete before switching states."

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.4_r1/android/content/SharedPreferences.java#SharedPreferences.Editor.apply%28%29