Merge pull request #649 from hex108/preempt

Preempt lowest priority task first

pkg/scheduler/actions/preempt/preempt.go

@@ -220,8 +220,15 @@ func preempt(
 			continue
 		}
 
-		// Preempt victims for tasks.
-		for _, preemptee := range victims {
+		victimsQueue := util.NewPriorityQueue(func(l, r interface{}) bool {
+			return !ssn.TaskOrderFn(l, r)
+		})
+		for _, victim := range victims {
+			victimsQueue.Push(victim)
+		}
+		// Preempt victims for tasks, pick lowest priority task first.
+		for !victimsQueue.Empty() {
+			preemptee := victimsQueue.Pop().(*api.TaskInfo)
 			glog.Errorf("Try to preempt Task <%s/%s> for Tasks <%s/%s>",
 				preemptee.Namespace, preemptee.Name, preemptor.Namespace, preemptor.Name)
 			if err := stmt.Evict(preemptee, "preempt"); err != nil {