statistics: rightly deal with timout when to send sync load (#57712)

pkg/statistics/handle/syncload/BUILD.bazel

@@ -33,7 +33,7 @@ go_test(
     srcs = ["stats_syncload_test.go"],
     flaky = True,
     race = "on",
-    shard_count = 5,
+    shard_count = 6,
     deps = [
         ":syncload",
         "//pkg/config",

pkg/statistics/handle/syncload/stats_syncload.go

@@ -40,7 +40,7 @@ import (
 )
 
 // RetryCount is the max retry count for a sync load task.
-const RetryCount = 3
+const RetryCount = 2
 
 type statsSyncLoad struct {
 	statsHandle statstypes.StatsHandle
@@ -96,9 +96,13 @@ func (s *statsSyncLoad) SendLoadRequests(sc *stmtctx.StatementContext, neededHis
 			}
 			select {
 			case s.StatsLoad.NeededItemsCh <- task:
-				result, ok := <-task.ResultCh
-				intest.Assert(ok, "task.ResultCh cannot be closed")
-				return result, nil
+				select {
+				case <-timer.C:
+					return nil, errors.New("sync load took too long to return")
+				case result, ok := <-task.ResultCh:
+					intest.Assert(ok, "task.ResultCh cannot be closed")
+					return result, nil
+				}
 			case <-timer.C:
 				return nil, errors.New("sync load stats channel is full and timeout sending task to channel")
 			}

pkg/statistics/handle/syncload/stats_syncload_test.go

@@ -344,3 +344,47 @@ func TestRetry(t *testing.T) {
 	}
 	require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/pkg/statistics/handle/syncload/mockReadStatsForOneFail"))
 }
+
+func TestSendLoadRequestsWaitTooLong(t *testing.T) {
+	originConfig := config.GetGlobalConfig()
+	newConfig := config.NewConfig()
+	newConfig.Performance.StatsLoadConcurrency = -1 // no worker to consume channel
+	newConfig.Performance.StatsLoadQueueSize = 10000
+	config.StoreGlobalConfig(newConfig)
+	defer config.StoreGlobalConfig(originConfig)
+	store, dom := testkit.CreateMockStoreAndDomain(t)
+
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t(a int, b int, c int, primary key(a), key idx(b,c))")
+	tk.MustExec("insert into t values (1,1,1),(2,2,2),(3,3,3)")
+
+	oriLease := dom.StatsHandle().Lease()
+	dom.StatsHandle().SetLease(1)
+	defer func() {
+		dom.StatsHandle().SetLease(oriLease)
+	}()
+	tk.MustExec("analyze table t all columns")
+	h := dom.StatsHandle()
+	is := dom.InfoSchema()
+	tbl, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	require.NoError(t, err)
+	tableInfo := tbl.Meta()
+	neededColumns := make([]model.StatsLoadItem, 0, len(tableInfo.Columns))
+	for _, col := range tableInfo.Columns {
+		neededColumns = append(neededColumns, model.StatsLoadItem{TableItemID: model.TableItemID{TableID: tableInfo.ID, ID: col.ID, IsIndex: false}, FullLoad: true})
+	}
+	stmtCtx := stmtctx.NewStmtCtx()
+	timeout := time.Nanosecond * 100
+	require.NoError(t, h.SendLoadRequests(stmtCtx, neededColumns, timeout))
+	for _, resultCh := range stmtCtx.StatsLoad.ResultCh {
+		rs1 := <-resultCh
+		require.Error(t, rs1.Err)
+	}
+	stmtCtx1 := stmtctx.NewStmtCtx()
+	require.NoError(t, h.SendLoadRequests(stmtCtx1, neededColumns, timeout))
+	for _, resultCh := range stmtCtx1.StatsLoad.ResultCh {
+		rs1 := <-resultCh
+		require.Error(t, rs1.Err)
+	}
+}