Merge pull request #105085 from MikeSpreitzer/fix-queueset-tests

Update TestNoRestraint and TestWindup

staging/src/k8s.io/apiserver/pkg/util/flowcontrol/fairqueuing/queueset/queueset_test.go

@@ -413,8 +413,19 @@ func TestMain(m *testing.M) {
 }
 
 // TestNoRestraint tests whether the no-restraint factory gives every client what it asks for
+// even though that is unfair.
 func TestNoRestraint(t *testing.T) {
 	metrics.Register()
+	testCases := []struct {
+		concurrency int
+		fair        bool
+	}{
+		{concurrency: 10, fair: true},
+		{concurrency: 2, fair: false},
+	}
+	for _, testCase := range testCases {
+		subName := fmt.Sprintf("concurrency=%v", testCase.concurrency)
+		t.Run(subName, func(t *testing.T) {
 			now := time.Now()
 			clk, counter := testeventclock.NewFake(now, 0, nil)
 			nrc, err := test.NewNoRestraintFactory().BeginConstruction(fq.QueuingConfig{}, newObserverPair(clk))
@@ -422,20 +433,22 @@ func TestNoRestraint(t *testing.T) {
 				t.Fatal(err)
 			}
 			nr := nrc.Complete(fq.DispatchingConfig{})
-	uniformScenario{name: "NoRestraint",
+			uniformScenario{name: "NoRestraint/" + subName,
 				qs: nr,
 				clients: []uniformClient{
 					newUniformClient(1001001001, 5, 10, time.Second, time.Second),
 					newUniformClient(2002002002, 2, 10, time.Second, time.Second/2),
 				},
-		concurrencyLimit:       10,
+				concurrencyLimit:       testCase.concurrency,
 				evalDuration:           time.Second * 15,
-		expectedFair:           []bool{true},
+				expectedFair:           []bool{testCase.fair},
 				expectedFairnessMargin: []float64{0.1},
 				expectAllRequests:      true,
 				clk:                    clk,
 				counter:                counter,
 			}.exercise(t)
+		})
+	}
 }
 
 func TestBaseline(t *testing.T) {
@@ -733,9 +746,9 @@ func TestTooWide(t *testing.T) {
 			newUniformClient(90090090090090, 15, 21, time.Second, time.Second-1).seats(7),
 		},
 		concurrencyLimit:       6,
-		evalDuration:           time.Second * 40,
+		evalDuration:           time.Second * 435,
 		expectedFair:           []bool{true},
-		expectedFairnessMargin: []float64{0.38},
+		expectedFairnessMargin: []float64{0.375},
 		expectAllRequests:      true,
 		evalInqueueMetrics:     true,
 		evalExecutingMetrics:   true,
@@ -744,14 +757,36 @@ func TestTooWide(t *testing.T) {
 	}.exercise(t)
 }
 
+// TestWindup exercises a scenario with the windup problem.
+// That is, a flow that can not use all the seats that it is allocated
+// for a while.  During that time, the queues that serve that flow
+// advance their `virtualStart` (that is, R(next dispatch in virtual world))
+// more slowly than the other queues (which are using more seats than they
+// are allocated).  The implementation has a hack that addresses part of
+// this imbalance but not all of it.  In this test, flow 1 can not use all
+// of its allocation during the first half, and *can* (and does) use all of
+// its allocation and more during the second half.
+// Thus we expect the fair (not equal) result
+// in the first half and an unfair result in the second half.
+// This func has two test cases, bounding the amount of unfairness
+// in the second half.
 func TestWindup(t *testing.T) {
 	metrics.Register()
+	testCases := []struct {
+		margin2     float64
+		expectFair2 bool
+	}{
+		{margin2: 0.26, expectFair2: true},
+		{margin2: 0.1, expectFair2: false},
+	}
+	for _, testCase := range testCases {
+		subName := fmt.Sprintf("m2=%v", testCase.margin2)
+		t.Run(subName, func(t *testing.T) {
 			now := time.Now()
-
 			clk, counter := testeventclock.NewFake(now, 0, nil)
 			qsf := newTestableQueueSetFactory(clk, countingPromiseFactoryFactory(counter))
 			qCfg := fq.QueuingConfig{
-		Name:             "TestWindup",
+				Name:             "TestWindup/" + subName,
 				DesiredNumQueues: 9,
 				QueueLengthLimit: 6,
 				HandSize:         1,
@@ -770,14 +805,16 @@ func TestWindup(t *testing.T) {
 				},
 				concurrencyLimit:       3,
 				evalDuration:           time.Second * 40,
-		expectedFair:           []bool{true, true},
-		expectedFairnessMargin: []float64{0.1, 0.26},
+				expectedFair:           []bool{true, testCase.expectFair2},
+				expectedFairnessMargin: []float64{0.1, testCase.margin2},
 				expectAllRequests:      true,
 				evalInqueueMetrics:     true,
 				evalExecutingMetrics:   true,
 				clk:                    clk,
 				counter:                counter,
 			}.exercise(t)
+		})
+	}
 }
 
 func TestDifferentFlowsWithoutQueuing(t *testing.T) {