Removing concurrency issues from Random Picker (#1314)

Author: kfswain

pkg/epp/scheduling/framework/plugins/picker/max_score_picker.go

@@ -87,8 +87,13 @@ func (p *MaxScorePicker) Pick(ctx context.Context, cycleState *types.CycleState,
 	log.FromContext(ctx).V(logutil.DEBUG).Info(fmt.Sprintf("Selecting maximum '%d' pods from %d candidates sorted by max score: %+v", p.maxNumOfEndpoints,
 		len(scoredPods), scoredPods))
 
+	// TODO: merge this with the logic in RandomPicker
+	// Rand package is not safe for concurrent use, so we create a new instance.
+	// Source: https://pkg.go.dev/math/rand#pkg-overview
+	randomGenerator := rand.New(rand.NewSource(time.Now().UnixNano()))
+
 	// Shuffle in-place - needed for random tie break when scores are equal
-	p.randomGenerator.Shuffle(len(scoredPods), func(i, j int) {
+	randomGenerator.Shuffle(len(scoredPods), func(i, j int) {
 		scoredPods[i], scoredPods[j] = scoredPods[j], scoredPods[i]
 	})
 

pkg/epp/scheduling/framework/plugins/picker/random_picker.go

@@ -58,15 +58,13 @@ func NewRandomPicker(maxNumOfEndpoints int) *RandomPicker {
 	return &RandomPicker{
 		typedName:         plugins.TypedName{Type: RandomPickerType, Name: RandomPickerType},
 		maxNumOfEndpoints: maxNumOfEndpoints,
-		randomGenerator:   rand.New(rand.NewSource(time.Now().UnixNano())),
 	}
 }
 
 // RandomPicker picks random pod(s) from the list of candidates.
 type RandomPicker struct {
 	typedName         plugins.TypedName
 	maxNumOfEndpoints int
-	randomGenerator   *rand.Rand // randomGenerator for randomly pick endpoint on tie-break
 }
 
 // WithName sets the name of the picker.
@@ -85,8 +83,13 @@ func (p *RandomPicker) Pick(ctx context.Context, _ *types.CycleState, scoredPods
 	log.FromContext(ctx).V(logutil.DEBUG).Info(fmt.Sprintf("Selecting maximum '%d' pods from %d candidates randomly: %+v", p.maxNumOfEndpoints,
 		len(scoredPods), scoredPods))
 
+	// TODO: merge this with the logic in MaxScorePicker
+	// Rand package is not safe for concurrent use, so we create a new instance.
+	// Source: https://pkg.go.dev/math/rand#pkg-overview
+	randomGenerator := rand.New(rand.NewSource(time.Now().UnixNano()))
+
 	// Shuffle in-place
-	p.randomGenerator.Shuffle(len(scoredPods), func(i, j int) {
+	randomGenerator.Shuffle(len(scoredPods), func(i, j int) {
 		scoredPods[i], scoredPods[j] = scoredPods[j], scoredPods[i]
 	})