2.1.20 flow_control 命令

2.1.20.1 查询流量控制当前配置状态

mysql> flow_control @@show;
+-------------------+-------------------------+------------------------+
| FLOW_CONTROL_TYPE | FLOW_CONTROL_HIGH_LEVEL | FLOW_CONTROL_LOW_LEVEL |
+-------------------+-------------------------+------------------------+
| FRONT_END         |                 4194304 |                 262144 |
| dbGroup1-hostM1   |                 4194304 |                 262144 |
| dbGroup2-hostM2   |                 4194304 |                 262144 |
+-------------------+-------------------------+------------------------+
1 row in set (0.00 sec)

列描述：

• FLOW_CONTROL_TYPE 流量控制的类型，前端连接为固定值“FRONT_END”;后段连接为所在的实例名，格式为：组名-实例名
• FLOW_CONTROL_HIGH_LEVEL 流量控制的高水位线，积压队列的字节数到达此位置开始控制流量
• FLOW_CONTROL_LOW_LEVEL 流量控制低水位线，积压队列的字节数低于此位置不再控制流量

2.1.20.2 修改流量控制当前配置状态

flow_control @@set [enableFlowControl = true/false] [flowControlHighLevel = ?] [flowControlLowLevel = ?]

MySQL [(none)]> flow_control @@set enableFlowControl = true flowControlHighLevel= 100000 flowControlLowLevel = 30000;
Query OK, 0 rows affected (0.02 sec)

通过此命令可以修改对应内存中生效的值，同时会变更文件bootstrap.dynamic.cnf 将其固化，对应关系如下：

• enableFlowControl： bootstrap.cnf中enableFlowControl参数
• flowControlHighLevel：bootstrap.cnf中flowControlHighLevel参数
• flowControlLowLevel：bootstrap.cnf中flowControlLowLevel参数

注：以上命令三个参数顺序不可变更

2.1.20.3 查看当前连接的流量控制状态

MySQL [(none)]> flow_control @@list;
+------------------+---------------+---------------------------------------+---------------------+---------------------+-----------------+
| CONNECTION_TYPE  | CONNECTION_ID | CONNECTION_INFO                       | WRITING_QUEUE_BYTES | READING_QUEUE_BYTES | FLOW_CONTROLLED |
+------------------+---------------+---------------------------------------+---------------------+---------------------+-----------------+
| ServerConnection |             1 | 127.0.0.1:50817/schema1 user = root   |              464594 |                NULL | false           |
| MySQLConnection  |             8 | 10.186.65.86:3307/db2 mysqlId = 1287  |                   0 |                   0 | false           |
| MySQLConnection  |            12 | 10.186.65.86:3308/db1 mysqlId = 1557  |                   0 |                   0 | false           |
| MySQLConnection  |             6 | 10.186.65.86:3307/db1 mysqlId = 1285  |                   0 |               86172 | false           |
| MySQLConnection  |            15 | 10.186.65.86:3308/db2 mysqlId = 1559  |                   0 |                   0 | false           |
+------------------+---------------+---------------------------------------+---------------------+---------------------+-----------------+

列描述：

• CONNECTION_TYPE 连接的类型，固定为MySQLConnection/ServerConnection其中之一
• CONNECTION_ID 连接在dble中的ID信息，可以通过ID查找日志
• CONNECTION_INFO 连接详细信息，使用端口，IP地址，用户，MySQL中的连接ID等
• WRITING_QUEUE_BYTES 当前连接的准备写出的队列里积压的字节数
• READING_QUEUE_BYTES 当前连接的已经读取的队列里积压的字节数，前端连接不支持此功能，恒为null
• FLOW_CONTROLLED 当前连接是否处于被流控的状态

如果需要过滤结果集，可以使用dble_information.dble_flow_control 来过滤