两台 mysql 5.5 服务器互为主从，使且半同步模式，网络终断后，但是 同步未能恢复
mysql> show status like 'Rpl_%';
+--------------------------------------------+-------------+
| Variable_name | Value |
+--------------------------------------------+-------------+
| Rpl_semi_sync_master_clients | 0 |
| Rpl_semi_sync_master_net_avg_wait_time | 213 |
| Rpl_semi_sync_master_net_wait_time | 51387187879 |
| Rpl_semi_sync_master_net_waits | 240543674 |
| Rpl_semi_sync_master_no_times | 2 |
| Rpl_semi_sync_master_no_tx | 6402 |
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 276 |
| Rpl_semi_sync_master_tx_wait_time | 68522585281 |
| Rpl_semi_sync_master_tx_waits | 248230976 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 1101735 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 240799932 |
| Rpl_semi_sync_slave_status | ON |
| Rpl_status | AUTH_MASTER |
+--------------------------------------------+-------------+
恢复操作
STOP SLAVE;
CHANGE MASTER TO master_heartbeat_period= milliseconds;
START SLAVE;