前置基础参考:https://www.cnblogs.com/gered/p/15868767.html#autoid-4-0-0
当前架构
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10秒就超时(这个阈值是连接超时)反馈出来了,但如果我们的DML、select 等其他操作 超过10秒是没有关系的;
主库挂了,非 mysql_query_rules 定位到从组的请求,都会连不上,我们查看一下相关日志
select * from runtime_mysql_servers; select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_ping_log where ping_error is not null limit 10; select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_connect_log where connect_error is not null order by time_start_us desc limit 10; select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_read_only_log where error is not null limit 10;
结果:
admin@mysqldb 17:02:48 [(none)]>select * from runtime_mysql_servers; +--------------+----------------+------+-----------+---------+--------+-------------+-----------------+---------------------+---------+----------------+---------+ | hostgroup_id | hostname | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment | +--------------+----------------+------+-----------+---------+--------+-------------+-----------------+---------------------+---------+----------------+---------+ | 10 | 192.168.148.39 | 3306 | 0 | SHUNNED | 1 | 0 | 1000 | 0 | 0 | 0 | | | 20 | 192.168.148.30 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | | | 20 | 192.168.148.27 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | | +--------------+----------------+------+-----------+---------+--------+-------------+-----------------+---------------------+---------+----------------+---------+ 3 rows in set (0.00 sec) admin@mysqldb 17:02:52 [(none)]>select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_ping_log where ping_error is not null limit 10; +---------------------+----------------+------+------------------+----------------------+---------------------------------------------------------+ | datetime | hostname | port | time_start_us | ping_success_time_us | ping_error | +---------------------+----------------+------+------------------+----------------------+---------------------------------------------------------+ | 2022-02-16 08:56:43 | 192.168.148.39 | 3306 | 1645001803735858 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:45 | 192.168.148.39 | 3306 | 1645001805750545 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:47 | 192.168.148.39 | 3306 | 1645001807770656 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:49 | 192.168.148.39 | 3306 | 1645001809742158 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:51 | 192.168.148.39 | 3306 | 1645001811771683 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:53 | 192.168.148.39 | 3306 | 1645001813752847 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:55 | 192.168.148.39 | 3306 | 1645001815746628 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:57 | 192.168.148.39 | 3306 | 1645001817742752 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:59 | 192.168.148.39 | 3306 | 1645001819728439 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:57:01 | 192.168.148.39 | 3306 | 1645001821729269 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | +---------------------+----------------+------+------------------+----------------------+---------------------------------------------------------+ 10 rows in set (0.00 sec) admin@mysqldb 17:02:52 [(none)]>select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_connect_log where connect_error is not null order by time_start_us desc limit 10; +---------------------+----------------+------+------------------+-------------------------+---------------------------------------------------------+ | datetime | hostname | port | time_start_us | connect_success_time_us | connect_error | +---------------------+----------------+------+------------------+-------------------------+---------------------------------------------------------+ | 2022-02-16 08:56:47 | 192.168.148.39 | 3306 | 1645001807770108 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:45 | 192.168.148.39 | 3306 | 1645001805716648 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:43 | 192.168.148.39 | 3306 | 1645001803713712 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:41 | 192.168.148.39 | 3306 | 1645001801713565 | 0 | Can't connect to MySQL server on '192.168.148.39' (115) | +---------------------+----------------+------+------------------+-------------------------+---------------------------------------------------------+ 4 rows in set (0.00 sec) admin@mysqldb 17:02:52 [(none)]>select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_read_only_log where error is not null limit 10; +---------------------+----------------+------+------------------+-----------------+-----------+---------------------------------------------------------------------------------------------+ | datetime | hostname | port | time_start_us | success_time_us | read_only | error | +---------------------+----------------+------+------------------+-----------------+-----------+---------------------------------------------------------------------------------------------+ | 2022-02-16 08:56:42 | 192.168.148.39 | 3306 | 1645001802730203 | 0 | NULL | Lost connection to MySQL server during query | | 2022-02-16 08:56:44 | 192.168.148.39 | 3306 | 1645001804750337 | 0 | NULL | timeout on creating new connection: Can't connect to MySQL server on '192.168.148.39' (115) | | 2022-02-16 08:56:46 | 192.168.148.39 | 3306 | 1645001806742312 | 0 | NULL | timeout on creating new connection: Can't connect to MySQL server on '192.168.148.39' (115) | +---------------------+----------------+------+------------------+-----------------+-----------+---------------------------------------------------------------------------------------------+ 3 rows in set (0.00 sec)
然后我们看一下最新的
select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_ping_log order by time_start_us desc limit 10; select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_connect_log order by time_start_us desc limit 10; select from_unixtime(time_start_us/1000/1000) as `datetime`,* from mysql_server_read_only_log order by time_start_us desc limit 10;
从下图我们可以看出, ping 还是一直不通,而 connect 、read_only 中甚至直接剔除对 主库 192.168.148.39 的连接尝试了
结合上面的所有,我们发现 ping_log 报错了 300次(2s一次的频率),而 connect_log(2秒一次的频率)只报了4次;
如下图,我们发现我们选中的参数,次数是3,所以就 connect 重试3次后,所以 connect_log 中只有4次记录是正常的;
恢复主库后:可无缝连上,现有连接无需重连,无需断开原长连接
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恢复后,我们看看 mysql server,hostgrou_id
我们可以看到,status 还是 shunned 状态
我们执行一个路由到主库的相关操作,它状态就变回来了;
关闭主库,从库1: 192.168.148.27 执行如下代码,变成 proxysql中的主库
stop slave; set global read_only=0;
如下图:
为什么主库变成下图这样,即在10 写组,又在20 读组?因为如下参数
mysql-monitor_writer_is_also_reader = true(当原read_only=1 的server read_only=0时,迁移一份到 writer 组的同时,也保留它的 reader 角色)
这个是为了避免故障转移后只有1个实例的时候,可以同时兼顾读写,从而业务连续;
我们再查询看看:是可以都读负载均衡分发的;写也是写到 我们的新主库 192.168.148.27 中去了;
注意:proxysql 连接在任意时候都没断开过,所以主从切换等情况不影响它的长连接,也不需要重连等等;