pkg: stop using math/rand.Seed

br/pkg/lightning/mydump/loader_test.go

@@ -1130,17 +1130,17 @@ func TestSampleParquetDataSize(t *testing.T) {
 	pwriter.PageSize = 8 * 1024              //8K
 	pwriter.CompressionType = parquet.CompressionCodec_SNAPPY
 	seed := time.Now().Unix()
-	t.Logf("seed: %d", seed)
-	rand.Seed(seed)
+	t.Logf("seed: %d. To reproduce the random behaviour, manually set `rand.New(rand.NewSource(seed))`", seed)
+	rnd := rand.New(rand.NewSource(seed))
 	totalRowSize := 0
 	for i := 0; i < 1000; i++ {
-		kl := rand.Intn(20) + 1
+		kl := rnd.Intn(20) + 1
 		key := make([]byte, kl)
-		kl, err = rand.Read(key)
+		kl, err = rnd.Read(key)
 		require.NoError(t, err)
-		vl := rand.Intn(20) + 1
+		vl := rnd.Intn(20) + 1
 		value := make([]byte, vl)
-		vl, err = rand.Read(value)
+		vl, err = rnd.Read(value)
 		require.NoError(t, err)
 
 		totalRowSize += kl + vl + 8

cmd/ddltest/ddl_test.go

@@ -1156,6 +1156,5 @@ func addEnvPath(newPath string) {
 }
 
 func init() {
-	rand.Seed(time.Now().UnixNano())
 	_ = store.Register("tikv", tidbdriver.TiKVDriver{})
 }

cmd/importer/rand.go

@@ -38,10 +38,6 @@ const (
 	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func randInt(min int, max int) int {
 	return min + rand.Intn(max-min+1)
 }

pkg/executor/internal/vecgroupchecker/vec_group_checker_test.go

@@ -18,7 +18,6 @@ import (
 	"fmt"
 	"math/rand"
 	"testing"
-	"time"
 
 	"github.com/pingcap/tidb/pkg/expression"
 	"github.com/pingcap/tidb/pkg/parser/mysql"
@@ -109,7 +108,6 @@ func genTestChunk4VecGroupChecker(chkRows []int, sameNum int) (expr []expression
 		numGroups = numRows/sameNum + 1
 	}
 
-	rand.Seed(time.Now().Unix())
 	nullPos := rand.Intn(numGroups)
 	cnt := 0
 	val := rand.Int63()

pkg/planner/core/tests/prepare/prepare_test.go

@@ -104,7 +104,6 @@ func TestRandomFlushPlanCache(t *testing.T) {
 		execStmts = append(execStmts, execStmt)
 	}
 
-	rand.Seed(time.Now().Unix())
 	for i := 0; i < 10; i++ {
 		// Warm up to make sure all the plans are in the cache.
 		for _, execStmt := range execStmts {

pkg/statistics/handle/updatetest/update_test.go

@@ -700,7 +700,6 @@ func TestMergeTopN(t *testing.T) {
 
 		topNs := make([]*statistics.TopN, 0, topnNum)
 		res := make(map[int]uint64)
-		rand.Seed(time.Now().Unix())
 		for i := 0; i < topnNum; i++ {
 			topN := statistics.NewTopN(n)
 			occur := make(map[int]bool)

pkg/store/driver/tikv_driver.go

@@ -18,7 +18,6 @@ import (
 	"context"
 	"crypto/tls"
 	"fmt"
-	"math/rand"
 	"net/url"
 	"strings"
 	"sync"
@@ -57,7 +56,6 @@ var mc storeCache
 
 func init() {
 	mc.cache = make(map[string]*tikvStore)
-	rand.Seed(time.Now().UnixNano())
 
 	// Setup the Hooks to dynamic control global resource controller.
 	variable.EnableGlobalResourceControlFunc = tikv.EnableResourceControl

pkg/util/chunk/list_test.go

@@ -161,12 +161,12 @@ func BenchmarkListGetRow(b *testing.B) {
 	for _, chk := range chks {
 		l.Add(chk)
 	}
-	rand.Seed(0)
+	rnd := rand.New(rand.NewSource(0))
 	ptrs := make([]RowPtr, 0, b.N)
 	for i := 0; i < min(b.N, 10000); i++ {
 		ptrs = append(ptrs, RowPtr{
-			ChkIdx: rand.Uint32() % uint32(numChk),
-			RowIdx: rand.Uint32() % uint32(numRow),
+			ChkIdx: rnd.Uint32() % uint32(numChk),
+			RowIdx: rnd.Uint32() % uint32(numRow),
 		})
 	}
 	for i := 10000; i < cap(ptrs); i++ {

pkg/util/chunk/row_in_disk_test.go

@@ -118,12 +118,12 @@ func BenchmarkDataInDiskByRowsGetRow(b *testing.B) {
 			b.Fatal(err)
 		}
 	}
-	rand.Seed(0)
+	rnd := rand.New(rand.NewSource(0))
 	ptrs := make([]RowPtr, 0, b.N)
 	for i := 0; i < min(b.N, 10000); i++ {
 		ptrs = append(ptrs, RowPtr{
-			ChkIdx: rand.Uint32() % uint32(numChk),
-			RowIdx: rand.Uint32() % uint32(numRow),
+			ChkIdx: rnd.Uint32() % uint32(numChk),
+			RowIdx: rnd.Uint32() % uint32(numRow),
 		})
 	}
 	for i := 10000; i < cap(ptrs); i++ {

pkg/util/importer/rand.go

@@ -34,10 +34,6 @@ const (
 	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func randInt(min int, max int) int {
 	return min + rand.Intn(max-min+1) // nolint:gosec
 }

pkg/util/selection/selection_test.go

@@ -18,7 +18,6 @@ import (
 	"math/rand"
 	"sort"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -84,7 +83,6 @@ func TestSelectionWithSerialCase(t *testing.T) {
 
 func randomTestCase(size int) testSlice {
 	data := make(testSlice, 0, size)
-	rand.Seed(time.Now().Unix())
 	for i := 0; i < size; i++ {
 		data = append(data, rand.Int()%100)
 	}

tools/check/ut.go

@@ -448,7 +448,6 @@ func main() {
 
 	// Get the correct count of CPU if it's in docker.
 	p = runtime.GOMAXPROCS(0)
-	rand.Seed(time.Now().Unix())
 	var err error
 	workDir, err = os.Getwd()
 	if err != nil {
@@ -953,7 +952,6 @@ func filter(input []string, f func(string) bool) []string {
 }
 
 func shuffle(tasks []task) {
-	rand.Seed(time.Now().UnixNano())
 	for i := 0; i < len(tasks); i++ {
 		pos := rand.Intn(len(tasks))
 		tasks[i], tasks[pos] = tasks[pos], tasks[i]