executor: kill tidb [session id] can't stop executors and release resources quickly

server/conn.go

@@ -112,6 +112,7 @@ type clientConn struct {
 	mu struct {
 		sync.RWMutex
 		cancelFunc context.CancelFunc
+		resultSets []ResultSet
 	}
 }
 
@@ -1047,6 +1048,9 @@ func (cc *clientConn) handleQuery(ctx context.Context, sql string) (err error) {
 		metrics.ExecuteErrorCounter.WithLabelValues(metrics.ExecuteErrorToLabel(err)).Inc()
 		return errors.Trace(err)
 	}
+	cc.mu.Lock()
+	cc.mu.resultSets = rs
+	cc.mu.Unlock()
 	if rs != nil {
 		if len(rs) == 1 {
 			err = cc.writeResultset(ctx, rs[0], false, 0, 0)

server/server.go

@@ -519,6 +519,12 @@ func killConn(conn *clientConn, query bool) {
 	}
 
 	conn.mu.RLock()
+	for _, resultSet := range conn.mu.resultSets {
+		// resultSet.Close() is reentrant so it's safe to kill a same connID multiple times
+		if err := resultSet.Close(); err != nil {
+			logutil.Logger(context.Background()).Error("close result set error", zap.Uint32("connID", conn.connectionID), zap.Error(err))
+		}
+	}
 	cancelFunc := conn.mu.cancelFunc
 	conn.mu.RUnlock()
 	if cancelFunc != nil {