cherry-pick pingcap#50969 to fix flaky test

Author: tangenta

server/conn_stmt_test.go

@@ -20,12 +20,6 @@ import (
 	"crypto/rand"
 	"encoding/binary"
 	"fmt"
-	"io/fs"
-	"os"
-	"path/filepath"
-	"strconv"
-	"strings"
-	"syscall"
 	"testing"
 
 	"github.com/pingcap/failpoint"
@@ -554,30 +548,17 @@ func TestCursorFetchErrorInFetch(t *testing.T) {
 
 	tk.MustExec(fmt.Sprintf("set tidb_mem_quota_query=%d", 1))
 
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/util/chunk/get-chunk-error", "return(true)"))
+	defer func() {
+		require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/util/chunk/get-chunk-error"))
+	}()
+
 	require.NoError(t, c.Dispatch(ctx, append(
 		appendUint32([]byte{mysql.ComStmtExecute}, uint32(stmt.ID())),
 		mysql.CursorTypeReadOnly, 0x1, 0x0, 0x0, 0x0,
 	)))
 
-	// close these disk files to produce error
-	filepath.Walk("/proc/self/fd", func(path string, info fs.FileInfo, err error) error {
-		if err != nil {
-			return nil
-		}
-		target, err := os.Readlink(path)
-		if err != nil {
-			return nil
-		}
-		if strings.HasPrefix(target, tmpStoragePath) {
-			fd, err := strconv.Atoi(filepath.Base(path))
-			require.NoError(t, err)
-			require.NoError(t, syscall.Close(fd))
-		}
-		return nil
-	})
-
-	// it'll get "bad file descriptor", as it has been closed in the test.
-	require.Error(t, c.Dispatch(ctx, appendUint32(appendUint32([]byte{mysql.ComStmtFetch}, uint32(stmt.ID())), 1024)))
+	require.ErrorContains(t, c.Dispatch(ctx, appendUint32(appendUint32([]byte{mysql.ComStmtFetch}, uint32(stmt.ID())), 1024)), "fail to get chunk for test")
 	// after getting a failed FETCH, the cursor should have been reseted
 	require.False(t, stmt.GetCursorActive())
 	require.Len(t, tk.Session().GetSessionVars().MemTracker.GetChildrenForTest(), 0)

util/chunk/row_container_reader.go

@@ -19,6 +19,8 @@ import (
 	"runtime"
 	"sync"
 
+	"github.com/pingcap/errors"
+	"github.com/pingcap/failpoint"
 	"github.com/pingcap/tidb/util/logutil"
 )
 
@@ -122,6 +124,11 @@ func (reader *rowContainerReader) startWorker() {
 
 		for chkIdx := 0; chkIdx < reader.rc.NumChunks(); chkIdx++ {
 			chk, err := reader.rc.GetChunk(chkIdx)
+			failpoint.Inject("get-chunk-error", func(val failpoint.Value) {
+				if val.(bool) {
+					err = errors.New("fail to get chunk for test")
+				}
+			})
 			if err != nil {
 				reader.err = err
 				return