domain: fast new a etcd session when the session is stale in the sche…

…maVersionSyncer (#7774)

ddl/syncer.go

@@ -18,7 +18,9 @@ import (
 	"math"
 	"strconv"
 	"sync"
+	"sync/atomic"
 	"time"
+	"unsafe"
 
 	"github.com/coreos/etcd/clientv3"
 	"github.com/coreos/etcd/clientv3/concurrency"
@@ -88,7 +90,7 @@ type SchemaSyncer interface {
 type schemaVersionSyncer struct {
 	selfSchemaVerPath string
 	etcdCli           *clientv3.Client
-	session           *concurrency.Session
+	session           unsafe.Pointer
 	mu                struct {
 		sync.RWMutex
 		globalVerCh clientv3.WatchChan
@@ -143,23 +145,32 @@ func (s *schemaVersionSyncer) Init(ctx context.Context) error {
 		return errors.Trace(err)
 	}
 	logPrefix := fmt.Sprintf("[%s] %s", ddlPrompt, s.selfSchemaVerPath)
-	s.session, err = owner.NewSession(ctx, logPrefix, s.etcdCli, owner.NewSessionDefaultRetryCnt, SyncerSessionTTL)
+	session, err := owner.NewSession(ctx, logPrefix, s.etcdCli, owner.NewSessionDefaultRetryCnt, SyncerSessionTTL)
 	if err != nil {
 		return errors.Trace(err)
 	}
+	s.storeSession(session)
 
 	s.mu.Lock()
 	s.mu.globalVerCh = s.etcdCli.Watch(ctx, DDLGlobalSchemaVersion)
 	s.mu.Unlock()
 
 	err = PutKVToEtcd(ctx, s.etcdCli, keyOpDefaultRetryCnt, s.selfSchemaVerPath, InitialVersion,
-		clientv3.WithLease(s.session.Lease()))
+		clientv3.WithLease(s.loadSession().Lease()))
 	return errors.Trace(err)
 }
 
+func (s *schemaVersionSyncer) loadSession() *concurrency.Session {
+	return (*concurrency.Session)(atomic.LoadPointer(&s.session))
+}
+
+func (s *schemaVersionSyncer) storeSession(session *concurrency.Session) {
+	atomic.StorePointer(&s.session, (unsafe.Pointer)(session))
+}
+
 // Done implements SchemaSyncer.Done interface.
 func (s *schemaVersionSyncer) Done() <-chan struct{} {
-	return s.session.Done()
+	return s.loadSession().Done()
 }
 
 // Restart implements SchemaSyncer.Restart interface.
@@ -176,12 +187,12 @@ func (s *schemaVersionSyncer) Restart(ctx context.Context) error {
 	if err != nil {
 		return errors.Trace(err)
 	}
-	s.session = session
+	s.storeSession(session)
 
 	childCtx, cancel := context.WithTimeout(ctx, keyOpDefaultTimeout)
 	defer cancel()
 	err = PutKVToEtcd(childCtx, s.etcdCli, putKeyRetryUnlimited, s.selfSchemaVerPath, InitialVersion,
-		clientv3.WithLease(s.session.Lease()))
+		clientv3.WithLease(s.loadSession().Lease()))
 
 	return errors.Trace(err)
 }
@@ -219,7 +230,7 @@ func (s *schemaVersionSyncer) UpdateSelfVersion(ctx context.Context, version int
 	startTime := time.Now()
 	ver := strconv.FormatInt(version, 10)
 	err := PutKVToEtcd(ctx, s.etcdCli, putKeyNoRetry, s.selfSchemaVerPath, ver,
-		clientv3.WithLease(s.session.Lease()))
+		clientv3.WithLease(s.loadSession().Lease()))
 
 	metrics.UpdateSelfVersionHistogram.WithLabelValues(metrics.RetLabel(err)).Observe(time.Since(startTime).Seconds())
 	return errors.Trace(err)

domain/domain.go

@@ -25,6 +25,7 @@ import (
 	"github.com/grpc-ecosystem/go-grpc-prometheus"
 	"github.com/ngaut/pools"
 	"github.com/pingcap/tidb/ast"
+	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/kv"
@@ -42,6 +43,7 @@ import (
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/keepalive"
 )
 
 // Domain represents a storage space. Different domains can use the same database name.
@@ -405,16 +407,16 @@ func (do *Domain) loadSchemaInLoop(lease time.Duration) {
 		case <-syncer.Done():
 			// The schema syncer stops, we need stop the schema validator to synchronize the schema version.
 			log.Info("[ddl] reload schema in loop, schema syncer need restart")
-			do.SchemaValidator.Stop()
 			err := do.mustRestartSyncer()
 			if err != nil {
 				log.Errorf("[ddl] reload schema in loop, schema syncer restart err %v", errors.ErrorStack(err))
 				break
 			}
-			do.SchemaValidator.Restart()
+			log.Info("[ddl] schema syncer restarted.")
 		case <-do.info.Done():
 			log.Info("[ddl] reload schema in loop, server info syncer need restart")
 			do.info.Restart(context.Background())
+			log.Info("[ddl] server info syncer restarted.")
 		case <-do.exit:
 			return
 		}
@@ -527,12 +529,19 @@ func NewDomain(store kv.Storage, ddlLease time.Duration, statsLease time.Duratio
 func (do *Domain) Init(ddlLease time.Duration, sysFactory func(*Domain) (pools.Resource, error)) error {
 	if ebd, ok := do.store.(EtcdBackend); ok {
 		if addrs := ebd.EtcdAddrs(); addrs != nil {
+			cfg := config.GetGlobalConfig()
 			cli, err := clientv3.New(clientv3.Config{
 				Endpoints:   addrs,
 				DialTimeout: 5 * time.Second,
 				DialOptions: []grpc.DialOption{
 					grpc.WithUnaryInterceptor(grpc_prometheus.UnaryClientInterceptor),
 					grpc.WithStreamInterceptor(grpc_prometheus.StreamClientInterceptor),
+					grpc.WithBackoffMaxDelay(time.Second * 3),
+					grpc.WithKeepaliveParams(keepalive.ClientParameters{
+						Time:                time.Duration(cfg.TiKVClient.GrpcKeepAliveTime) * time.Second,
+						Timeout:             time.Duration(cfg.TiKVClient.GrpcKeepAliveTimeout) * time.Second,
+						PermitWithoutStream: true,
+					}),
 				},
 				TLS: ebd.TLSConfig(),
 			})