[RyanCahoon]

Originally Posted by Ether

I was wondering what the "default" behavior is, for folks who use the framework and don't do anything too far out of the ordinary (like changing/tuning the scheduling algorithm).

Java looks like it uses the standard java.util.Timer/TimerTask. According to the docs:

Originally Posted by java.util.Timer

Corresponding to each Timer object is a single background thread that is used to execute all of the timer's tasks, sequentially. Timer tasks should complete quickly. If a timer task takes excessive time to complete, it "hogs" the timer's task execution thread. This can, in turn, delay the execution of subsequent tasks, which may "bunch up" and execute in rapid succession when (and if) the offending task finally completes.

The C++ version of WPIlib includes the Notifier class which seems to fill the periodic task niche. The code looks like it follows (1), however the task queue is shared globally among all instances of Notifier, so not only does a long-running task block successive instances of itself, it will block other periodic tasks as well. As you say, a knowledgeable programmer could modify this for better behavior with a long-running task by spawning a new task in the handler to complete the periodic job.