Returns true if possibly still triggerable. Used by cleanStack.
Performs completion action if triggered, returning a dependent that may need propagation, if one exists.
When an object implementing interface <code>Runnable</code> is used to create a thread, starting the thread causes the object's <code>run</code> method to be called in that separately executing thread. <p> The general contract of the method <code>run</code> is that it may take any action whatsoever.