实际生产和测试中，经常需要统计一个 OBProxy 集群中各个 OBProxy 的连接数，据此判断客户应用当前所有的连接是否均衡地发给了所有的 OBProxy，以及粗略判断当前系统的繁忙程度。
原理与实现
客户的应用程序连接到 OceanBase 数据库的完整链路一般包括 Client、LB 负载均衡设备、由多个 OBProxy 租户的 OBProxy 集群、OBServer 集群等多个组件，不难看出，从应用到 OceanBase 数据库的链路一般较长，中间会经过多次网络报文的转发：
这里 Client/LB -> OBProxy 维持的连接以及会话统称为 Client Session；OBProxy 可能和多个 OBServer 同时维持会话和连接，这里统称为 Server Session。
统计一个 OBProxy 当前的连接数时，一定要注意以下两点：
一个 OBProxy 集群本质上是一个个独立的 OBProxy 进程，多个 OBProxy 之间的连接是互不感知的，组成集群只是为了方便进行运维管理和参数的修改。
OBProxy 看到的连接是客户端连进来的，而 OBServer 看到的连接是 OBProxy 连进来的，这边的连接是两段不同的 TCP 连接。
可以使用如下几条 SQL 语句来查询统计某个 OBProxy 上当前所有的连接数：
方法一：通过 OBProxy IP+端口（默认的端口号：2883）连接到 root@sys 租户后，执行。
MySQL [(none)]> show proxysession;方法二：通过 OBProxy IP+端口（默认的端口号：2883）连接到 root@sys 租户后，执行。
MySQL [(none)]> show processlist; -- 注意不要使用show full processlist; 加了 full 以后看到的是整个 OBServer 集群所有 OBServer 的连接数。方法三：通过OBProxy IP+端口（默认的端口号：2883）连接到 root@sys 租户后，执行。
MySQL [(none)]> show proxystat refresh; -- 输出的倒数第四行 `client_connections_currently_open` 字段对应的值统计的就是当前 OBProxy 的连接数。
场景示例
测试准备，通过 sysbench 启动 10 个连接，连到单个 OBProxy IP，对OBServer 集群进行压测。
[admin@localhost:~]$ sysbench /home/admin/sysbench-1.0.16/src/lua/oltp_point_select.lua --mysql-db=sbtest --mysql-host=xxx.xxx.xxx.111 --mysql-port=2883 --mysql-user=root@perfmysql#oio_cluster --mysql-password='xxx' --tables=30 --table_size=1000000 --report-interval=1 --threads=10 --db-driver=mysql --time=600 --skip-trx=off --db-ps-mode=disable --create-secondary=off --rand-type=uniform --mysql-ignore-errors=6002,6004,4012,2013,4016,1213,1020,1205,4030,1235,1062,6012 run ;date输出压测日志内容如下：
sysbench 1.0.16 (using bundled LuaJIT 2.1.0-beta2) Running the test with following options: Number of threads: 10 Report intermediate results every 1 second(s) Initializing random number generator from current time Initializing worker threads... Threads started! [ 1s ] thds: 10 tps: 1161.82 qps: 1161.82 (r/w/o: 1161.82/0.00/0.00) lat (ms,95%): 10.09 err/s: 0.00 reconn/s: 0.00 [ 2s ] thds: 10 tps: 1174.09 qps: 1174.09 (r/w/o: 1174.09/0.00/0.00) lat (ms,95%): 10.09 err/s: 0.00 reconn/s: 0.00 [ 3s ] thds: 10 tps: 1172.01 qps: 1172.01 (r/w/o: 1172.01/0.00/0.00) lat (ms,95%): 10.09 err/s: 0.00 reconn/s: 0.00 [ 4s ] thds: 10 tps: 1170.00 qps: 1170.00 (r/w/o: 1170.00/0.00/0.00) lat (ms,95%): 10.09 err/s: 0.00 reconn/s: 0.00 [ 5s ] thds: 10 tps: 1168.98 qps: 1168.98 (r/w/o: 1168.98/0.00/0.00) lat (ms,95%): 9.91 err/s: 0.00 reconn/s: 0.00 [ 6s ] thds: 10 tps: 1170.01 qps: 1170.01 (r/w/o: 1170.01/0.00/0.00) lat (ms,95%): 10.09 err/s: 0.00 reconn/s: 0.00 [ 7s ] thds: 10 tps: 1169.01 qps: 1169.01 (r/w/o: 1169.01/0.00/0.00) lat (ms,95%): 10.09 err/s: 0.00 reconn/s: 0.00统计单个 OBProxy 当前的连接数的方法。
方法一：通过该 OBProxy 连接到 root@sys 租户后执行
show proxysession;命令。$ mysql -hxxx.xxx.xxx.111 -uroot@sys#oio\_cluster -P2883 -pxxx -A -c Welcome to the MariaDB monitor. Commands end with ; or \g. Your MySQL connection id is 1442148 Server version: 5.6.25 OceanBase 3.2.4.7 (r107010022023122913-1eba23192ff3365951f818121471f56a49b29a7f) (Built Dec 29 2023 13:55:55) Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MySQL [(none)\> show proxysession;输出结果如下：
+--------------------+---------+-------------+-----------+------+----------------------+--------+-------------+-------------------+-------------------+-------+-------+-----------+ | proxy_sessid | Id | Cluster | Tenant | User | Host | db | trans_count | svr_session\_count | state | tid | pid | using_ssl | +--------------------+---------+-------------+-----------+------+----------------------+--------+-------------+-------------------+-------------------+-------+-------+-----------+ | 839446818411728824 | 1442148 | oio_cluster | sys | root | xx.xxx.xx.xxx:49663 | NULL | 0 | 1 | MCS_ACTIVE_READER | 63333 | 63282 | 0 | | 839446818411728797 | 70018 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51380 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63282 | 63282 | 0 | | 839446818411728749 | 170964 | oio_cluster | oracle | sys | xx.xxx.xx.xxx:47821 | SYS | 0 | 3 | MCS_ACTIVE_READER | 63323 | 63282 | 0 | | 839446818411728798 | 337803 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51367 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63324 | 63282 | 0 | | 839446818411728799 | 447206 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51368 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63325 | 63282 | 0 | | 839446818411728802 | 542883 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51383 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63326 | 63282 | 0 | | 839446818411728801 | 661737 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51369 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63327 | 63282 | 0 | | 839446818411728800 | 787420 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51370 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63328 | 63282 | 0 | | 839446818411728803 | 920698 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51371 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63329 | 63282 | 0 | | 839446818411728804 | 1048828 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51382 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63330 | 63282 | 0 | | 839446818411728805 | 1179731 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51372 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63331 | 63282 | 0 | | 839446818411728806 | 1310733 | oio_cluster | perfmysql | root | xxx.xx.xxx.xxx:51381 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63332 | 63282 | 0 | +--------------------+---------+-------------+-----------+------+----------------------+--------+-------------+-------------------+-------------------+-------+-------+-----------+ 12 rows in set (0.00 sec)方法二：通过该 OBProxy 连接到 root@sys 租户后执行
show processlist;命令。$ mysql -hxxx.xxx.xxx.111 -uroot@sys#oio\_cluster -P2883 -pxxx -A -c Welcome to the MariaDB monitor. Commands end with ; or \g. Your MySQL connection id is 1442148 Server version: 5.6.25 OceanBase 3.2.4.7 (r107010022023122913-1eba23192ff3365951f818121471f56a49b29a7f) (Built Dec 29 2023 13:55:55) Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MySQL [(none)]> show processlist;输出结果如下：
+---------+-----------+------+----------------------+--------+-------------+-------------------+-------------------+-------+-------+ | Id | Tenant | User | Host | db | trans_count | svr_session_count | state | tid | pid | +---------+-----------+------+----------------------+--------+-------------+-------------------+-------------------+-------+-------+ | 1442148 | sys | root | xx.xxx.xx.xxx:49663 | NULL | 0 | 1 | MCS_ACTIVE_READER | 63333 | 63282 | | 70018 | perfmysql | root | xxx.xx.xxx.xxx:51380 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63282 | 63282 | | 170964 | oracle | sys | xx.xxx.xx.xxx:47821 | SYS | 0 | 3 | MCS_ACTIVE_READER | 63323 | 63282 | | 337803 | perfmysql | root | xxx.xx.xxx.xxx:51367 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63324 | 63282 | | 447206 | perfmysql | root | xxx.xx.xxx.xxx:51368 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63325 | 63282 | | 542883 | perfmysql | root | xxx.xx.xxx.xxx:51383 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63326 | 63282 | | 661737 | perfmysql | root | xxx.xx.xxx.xxx:51369 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63327 | 63282 | | 787420 | perfmysql | root | xxx.xx.xxx.xxx:51370 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63328 | 63282 | | 920698 | perfmysql | root | xxx.xx.xxx.xxx:51371 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63329 | 63282 | | 1048828 | perfmysql | root | xxx.xx.xxx.xxx:51382 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63330 | 63282 | | 1179731 | perfmysql | root | xxx.xx.xxx.xxx:51372 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63331 | 63282 | | 1310733 | perfmysql | root | xxx.xx.xxx.xxx:51381 | sbtest | 0 | 1 | MCS_ACTIVE_READER | 63332 | 63282 | +---------+-----------+------+----------------------+--------+-------------+-------------------+-------------------+-------+-------+ 12 rows in set (0.00 sec)方法三：通过该 OBProxy 连接到 root@sys 租户后执行
show proxystat refresh;命令。$ mysql -hxxx.xxx.xxx.111 -uroot@sys#oio\_cluster -P2883 -pxxx -A -c Welcome to the MariaDB monitor. Commands end with ; or \g. Your MySQL connection id is 1442148 Server version: 5.6.25 OceanBase 3.2.4.7 (r107010022023122913-1eba23192ff3365951f818121471f56a49b29a7f) (Built Dec 29 2023 13:55:55) Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MySQL \[(none)\]> show proxystat refresh;输出结果如下：
+---------------------------------------------+------------------+--------------+ | stat_name | value | persist_type | +---------------------------------------------+------------------+--------------+ | async_flush_log_speed | 11 | NULL | | dropped_debug_log_count | 0 | NULL | | dropped_trace_log_count | 0 | NULL | ... ... ... | global_client_connections_currently_open | 12 | NULL | | client_connections_currently_open | 12 | NULL | | write_bytes | 4048726835 | PERSISTENT | | read_bytes | 5607077717 | PERSISTENT | | net_handler_run | 683472619414 | NULL | +---------------------------------------------+------------------+--------------+ 217 rows in set (0.00 sec)
在同一个时刻，通过上面三种方法统计出来的，当前 OBProxy 的连接数，均一致。
适用版本
OBProxy V1.x 版本、OBProxy V3.x 版本、OBProxy V4.x 版本。
