domain: fix stats updating bug when no stats woker (#7864) (#7871)

Author: alivxxx

domain/domain.go

@@ -25,6 +25,7 @@ import (
 	"github.com/grpc-ecosystem/go-grpc-prometheus"
 	"github.com/juju/errors"
 	"github.com/ngaut/pools"
+	"github.com/ngaut/sync2"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/kv"
@@ -52,6 +53,7 @@ type Domain struct {
 	privHandle      *privileges.Handle
 	statsHandle     unsafe.Pointer
 	statsLease      time.Duration
+	statsUpdating   sync2.AtomicInt32
 	ddl             ddl.DDL
 	m               sync.Mutex
 	SchemaValidator SchemaValidator
@@ -592,6 +594,20 @@ func (do *Domain) CreateStatsHandle(ctx sessionctx.Context) {
 	atomic.StorePointer(&do.statsHandle, unsafe.Pointer(statistics.NewHandle(ctx, do.statsLease)))
 }
 
+// StatsUpdating checks if the stats worker is updating.
+func (do *Domain) StatsUpdating() bool {
+	return do.statsUpdating.Get() > 0
+}
+
+// SetStatsUpdating sets the value of stats updating.
+func (do *Domain) SetStatsUpdating(val bool) {
+	if val {
+		do.statsUpdating.Set(1)
+	} else {
+		do.statsUpdating.Set(0)
+	}
+}
+
 // RunAutoAnalyze indicates if this TiDB server starts auto analyze worker and can run auto analyze job.
 var RunAutoAnalyze = true
 
@@ -608,6 +624,7 @@ func (do *Domain) UpdateTableStatsLoop(ctx sessionctx.Context) error {
 	}
 	owner := do.newStatsOwner()
 	do.wg.Add(1)
+	do.SetStatsUpdating(true)
 	go do.updateStatsWorker(ctx, owner)
 	if RunAutoAnalyze {
 		do.wg.Add(1)
@@ -656,7 +673,11 @@ func (do *Domain) updateStatsWorker(ctx sessionctx.Context, owner owner.Manager)
 	} else {
 		log.Info("[stats] init stats info takes ", time.Now().Sub(t))
 	}
-	defer recoverInDomain("updateStatsWorker", false)
+	defer func() {
+		do.SetStatsUpdating(false)
+		recoverInDomain("updateStatsWorker", false)
+		do.wg.Done()
+	}()
 	for {
 		select {
 		case <-loadTicker.C:
@@ -665,7 +686,6 @@ func (do *Domain) updateStatsWorker(ctx sessionctx.Context, owner owner.Manager)
 				log.Debug("[stats] update stats info fail: ", errors.ErrorStack(err))
 			}
 		case <-do.exit:
-			do.wg.Done()
 			return
 			// This channel is sent only by ddl owner or the drop stats executor.
 		case t := <-statsHandle.DDLEventCh():

executor/analyze.go

@@ -69,7 +69,8 @@ func (e *AnalyzeExec) Next(ctx context.Context, chk *chunk.Chunk) error {
 	close(taskCh)
 	dom := domain.GetDomain(e.ctx)
 	lease := dom.StatsHandle().Lease
-	if lease > 0 {
+	// The analyze result will be consumed by background stats worker.
+	if lease > 0 && dom.StatsUpdating() {
 		var err1 error
 		for i := 0; i < len(e.tasks); i++ {
 			result := <-resultCh

executor/executor_test.go

@@ -107,6 +107,7 @@ func (s *testSuite) SetUpSuite(c *C) {
 	}
 	d, err := session.BootstrapSession(s.store)
 	c.Assert(err, IsNil)
+	d.SetStatsUpdating(true)
 	s.domain = d
 }
 

infoschema/tables_test.go

@@ -29,6 +29,7 @@ func (s *testSuite) TestDataForTableRowsCountField(c *C) {
 	defer store.Close()
 	do, err := session.BootstrapSession(store)
 	c.Assert(err, IsNil)
+	do.SetStatsUpdating(true)
 	defer do.Close()
 
 	h := do.StatsHandle()

plan/cbo_test.go

@@ -632,6 +632,7 @@ func newStoreWithBootstrap() (kv.Storage, *domain.Domain, error) {
 	session.SetSchemaLease(0)
 	session.SetStatsLease(0)
 	dom, err := session.BootstrapSession(store)
+	dom.SetStatsUpdating(true)
 	return store, dom, errors.Trace(err)
 }
 

session/session.go

@@ -1104,8 +1104,9 @@ func CreateSession(store kv.Storage) (Session, error) {
 	}
 	privilege.BindPrivilegeManager(s, pm)
 
-	// Add statsUpdateHandle.
-	if do.StatsHandle() != nil {
+	// Add stats collector, and it will be freed by background stats worker
+	// which periodically updates stats using the collected data.
+	if do.StatsHandle() != nil && do.StatsUpdating() {
 		s.statsCollector = do.StatsHandle().NewSessionStatsCollector()
 	}
 

statistics/handle_test.go

@@ -445,5 +445,6 @@ func newStoreWithBootstrap(statsLease time.Duration) (kv.Storage, *domain.Domain
 	session.SetStatsLease(statsLease)
 	domain.RunAutoAnalyze = false
 	do, err := session.BootstrapSession(store)
+	do.SetStatsUpdating(true)
 	return store, do, errors.Trace(err)
 }