server: close all connection directly when terminate tidb (#8692) (#8707

)

server/conn.go

@@ -153,6 +153,10 @@ func (cc *clientConn) Close() error {
 	delete(cc.server.clients, cc.connectionID)
 	connections := len(cc.server.clients)
 	cc.server.rwlock.Unlock()
+	return closeConn(cc, connections)
+}
+
+func closeConn(cc *clientConn, connections int) error {
 	metrics.ConnGauge.Set(float64(connections))
 	err := cc.bufReadConn.Close()
 	terror.Log(errors.Trace(err))
@@ -162,6 +166,11 @@ func (cc *clientConn) Close() error {
 	return nil
 }
 
+func (cc *clientConn) closeWithoutLock() error {
+	delete(cc.server.clients, cc.connectionID)
+	return closeConn(cc, len(cc.server.clients))
+}
+
 // writeInitialHandshake sends server version, connection ID, server capability, collation, server status
 // and auth salt to the client.
 func (cc *clientConn) writeInitialHandshake() error {

server/server.go

@@ -376,7 +376,14 @@ func (s *Server) KillAllConnections() {
 	log.Info("[server] kill all connections.")
 
 	for _, conn := range s.clients {
-		killConn(conn, false)
+		atomic.StoreInt32(&conn.status, connStatusShutdown)
+		terror.Log(errors.Trace(conn.closeWithoutLock()))
+		conn.mu.RLock()
+		cancelFunc := conn.mu.cancelFunc
+		conn.mu.RUnlock()
+		if cancelFunc != nil {
+			cancelFunc()
+		}
 	}
 }