server: close the temporary session in HTTP API to avoid memory leak

server/http_handler.go

@@ -45,7 +45,6 @@ import (
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/meta"
 	"github.com/pingcap/tidb/session"
-	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/sessionctx/binloginfo"
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
@@ -355,11 +354,11 @@ func (t *tikvHandlerTool) getPartition(tableVal table.Table, partitionName strin
 }
 
 func (t *tikvHandlerTool) schema() (infoschema.InfoSchema, error) {
-	session, err := session.CreateSession(t.Store)
+	dom, err := session.GetDomain(t.Store)
 	if err != nil {
-		return nil, errors.Trace(err)
+		return nil, err
 	}
-	return domain.GetDomain(session.(sessionctx.Context)).InfoSchema(), nil
+	return dom.InfoSchema(), nil
 }
 
 func (t *tikvHandlerTool) handleMvccGetByHex(params map[string]string) (*mvccKV, error) {
@@ -712,14 +711,13 @@ func (h settingsHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 			}
 		}
 		if asyncCommit := req.Form.Get("tidb_enable_async_commit"); asyncCommit != "" {
-			s, err := session.CreateSession(h.Store.(kv.Storage))
+			s, err := session.CreateSession(h.Store)
 			if err != nil {
 				writeError(w, err)
 				return
 			}
-			if s != nil {
-				defer s.Close()
-			}
+			defer s.Close()
+
 			switch asyncCommit {
 			case "0":
 				err = s.GetSessionVars().GlobalVarsAccessor.SetGlobalSysVar(variable.TiDBEnableAsyncCommit, variable.Off)
@@ -735,14 +733,13 @@ func (h settingsHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 			}
 		}
 		if onePC := req.Form.Get("tidb_enable_1pc"); onePC != "" {
-			s, err := session.CreateSession(h.Store.(kv.Storage))
+			s, err := session.CreateSession(h.Store)
 			if err != nil {
 				writeError(w, err)
 				return
 			}
-			if s != nil {
-				defer s.Close()
-			}
+			defer s.Close()
+
 			switch onePC {
 			case "0":
 				err = s.GetSessionVars().GlobalVarsAccessor.SetGlobalSysVar(variable.TiDBEnable1PC, variable.Off)
@@ -878,14 +875,11 @@ func (h flashReplicaHandler) getTiFlashReplicaInfo(tblInfo *model.TableInfo, rep
 }
 
 func (h flashReplicaHandler) getDropOrTruncateTableTiflash(currentSchema infoschema.InfoSchema) ([]*tableFlashReplicaInfo, error) {
-	s, err := session.CreateSession(h.Store.(kv.Storage))
+	s, err := session.CreateSession(h.Store)
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
-
-	if s != nil {
-		defer s.Close()
-	}
+	defer s.Close()
 
 	store := domain.GetDomain(s).Store()
 	txn, err := store.Begin()
@@ -948,16 +942,18 @@ func (h flashReplicaHandler) handleStatusReport(w http.ResponseWriter, req *http
 		writeError(w, err)
 		return
 	}
-	do, err := session.GetDomain(h.Store.(kv.Storage))
+	do, err := session.GetDomain(h.Store)
 	if err != nil {
 		writeError(w, err)
 		return
 	}
-	s, err := session.CreateSession(h.Store.(kv.Storage))
+	s, err := session.CreateSession(h.Store)
 	if err != nil {
 		writeError(w, err)
 		return
 	}
+	defer s.Close()
+
 	available := status.checkTableFlashReplicaAvailable()
 	err = do.DDL().UpdateTableReplicaInfo(s, status.ID, available)
 	if err != nil {
@@ -1123,18 +1119,7 @@ func (h ddlHistoryJobHandler) ServeHTTP(w http.ResponseWriter, req *http.Request
 }
 
 func (h ddlHistoryJobHandler) getAllHistoryDDL() ([]*model.Job, error) {
-	s, err := session.CreateSession(h.Store.(kv.Storage))
-	if err != nil {
-		return nil, errors.Trace(err)
-	}
-
-	if s != nil {
-		defer s.Close()
-	}
-
-	store := domain.GetDomain(s.(sessionctx.Context)).Store()
-	txn, err := store.Begin()
-
+	txn, err := h.Store.Begin()
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
@@ -1741,7 +1726,7 @@ type serverInfo struct {
 
 // ServeHTTP handles request of ddl server info.
 func (h serverInfoHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	do, err := session.GetDomain(h.Store.(kv.Storage))
+	do, err := session.GetDomain(h.Store)
 	if err != nil {
 		writeError(w, errors.New("create session error"))
 		log.Error(err)
@@ -1771,7 +1756,7 @@ type clusterServerInfo struct {
 
 // ServeHTTP handles request of all ddl servers info.
 func (h allServerInfoHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	do, err := session.GetDomain(h.Store.(kv.Storage))
+	do, err := session.GetDomain(h.Store)
 	if err != nil {
 		writeError(w, errors.New("create session error"))
 		log.Error(err)
@@ -1872,6 +1857,8 @@ func (h profileHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		writeError(w, err)
 		return
 	}
+	defer sctx.Close()
+
 	var start, end time.Time
 	if req.FormValue("end") != "" {
 		end, err = time.ParseInLocation(time.RFC3339, req.FormValue("end"), sctx.GetSessionVars().Location())

server/sql_info_fetcher.go

@@ -81,6 +81,7 @@ func (sh *sqlInfoFetcher) zipInfoForSQL(w http.ResponseWriter, r *http.Request)
 		return
 	}
 	defer sh.s.Close()
+
 	sh.do = domain.GetDomain(sh.s)
 	reqCtx := r.Context()
 	sql := r.FormValue("sql")

server/statistics_handler.go

@@ -92,6 +92,8 @@ func (sh StatsHistoryHandler) ServeHTTP(w http.ResponseWriter, req *http.Request
 		writeError(w, err)
 		return
 	}
+	defer se.Close()
+
 	se.GetSessionVars().StmtCtx.TimeZone = time.Local
 	t, err := types.ParseTime(se.GetSessionVars().StmtCtx, params[pSnapshot], mysql.TypeTimestamp, 6)
 	if err != nil {