fix random string used in test allocating 50MB in Cortex binary (#5903)

Signed-off-by: Ben Ye <[email protected]>

Author: yeya24

pkg/distributor/distributor_test.go

@@ -57,6 +57,14 @@ var (
 	emptyResponse = &cortexpb.WriteResponse{}
 )
 
+var (
+	randomStrings = []string{}
+)
+
+func init() {
+	randomStrings = util.GenerateRandomStrings()
+}
+
 func TestConfig_Validate(t *testing.T) {
 	t.Parallel()
 	tests := map[string]struct {
@@ -2466,8 +2474,8 @@ func prepare(tb testing.TB, cfg prepConfig) ([]*Distributor, []*mockIngester, []
 	// Strings to be used for get labels values/Names
 	var unusedStrings []string
 	if cfg.lblValuesPerIngester > 0 {
-		unusedStrings = make([]string, min(len(util.RandomStrings), cfg.numIngesters*cfg.lblValuesPerIngester))
-		copy(unusedStrings, util.RandomStrings)
+		unusedStrings = make([]string, min(len(randomStrings), cfg.numIngesters*cfg.lblValuesPerIngester))
+		copy(unusedStrings, randomStrings)
 	}
 	s := &prepState{
 		unusedStrings: unusedStrings,

pkg/util/strings_test.go

@@ -48,6 +48,7 @@ func BenchmarkMergeSlicesParallel(b *testing.B) {
 		},
 	}
 
+	randomStrings := GenerateRandomStrings()
 	type ParallelismType int
 
 	const (
@@ -58,9 +59,9 @@ func BenchmarkMergeSlicesParallel(b *testing.B) {
 
 	for _, tc := range testCases {
 		input := make([][]string, tc.inputSize)
-		unusedStrings := make([]string, min(len(RandomStrings), tc.inputSize*tc.stringsPerInput))
+		unusedStrings := make([]string, min(len(randomStrings), tc.inputSize*tc.stringsPerInput))
 		usedStrings := make([]string, 0, len(unusedStrings))
-		copy(unusedStrings, RandomStrings)
+		copy(unusedStrings, randomStrings)
 
 		for i := 0; i < tc.inputSize; i++ {
 			stringsToBeReused := make([]string, len(usedStrings))

pkg/util/test_util.go

@@ -5,19 +5,17 @@ import (
 	"strings"
 )
 
-var (
-	randomChar    = "0123456789abcdef"
-	RandomStrings = []string{}
-)
-
-func init() {
+func GenerateRandomStrings() []string {
+	randomChar := "0123456789abcdef"
+	randomStrings := make([]string, 0, 1000000)
 	sb := strings.Builder{}
 	for i := 0; i < 1000000; i++ {
 		sb.Reset()
 		sb.WriteString("pod://")
 		for j := 0; j < 14; j++ {
 			sb.WriteByte(randomChar[rand.Int()%len(randomChar)])
 		}
-		RandomStrings = append(RandomStrings, sb.String())
+		randomStrings = append(randomStrings, sb.String())
 	}
+	return randomStrings
 }