var queue = new ConcurrentQueue<Action>(actions);
Task.Factory.StartNew(() => {
 Action a;
 while (queue.TryDequeue(out a))
 {
  a();
 }
});
Task.Factory.StartNew(() => {
 Action a;
 while (queue.TryDequeue(out a))
 {
  a();
 }
});

次の条件はなんだい馬鹿ども。