关于MySQL优化----wait_timeout和interactive_timeout的设置问题的疑惑
MySQL中的配置参数interactive_timeout和wait_timeout
MySQL服务器所支持的最大连接数是有上限的,因为每个连接的建立都会消耗内存,因此我们希望客户端在连接到MySQL Server处理完相应的操作后,应该断开连接并释放占用的内存。如果你的MySQL Server有大量的闲置连接,他们不仅会白白消耗内存,而且如果连接一直在累加而不断开,最终肯定会达到MySQL Server的连接上限数,这会报'too many connections'的错误。对于wait_timeout的值设定,应该根据系统的运行情况来判断。在系统运行一段时间后,可以通过show processlist命令查看当前系统的连接状态,如果发现有大量的sleep状态的连接进程,则说明该参数设置的过大,可以进行适当的调整小些。我按照这个提示 操作如下
mysql> show variables like '%timeout%';
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| interactive_timeout | 28800 |
| net_read_timeout | 30 |
| net_write_timeout | 60 |
| slave_net_timeout | 3600 |
| table_lock_wait_timeout | 50 |
| wait_timeout | 28800 |
+-------------------------+-------+
8 rows in set (0.00 sec)mysql> set global wait_timeout=300 ,interactive_timeout=300;退出 重新登录。。mysql> show variables like '%timeout%';
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| interactive_timeout | 300 |
| net_read_timeout | 30 |
| net_write_timeout | 60 |
| slave_net_timeout | 3600 |
| table_lock_wait_timeout | 50 |
| wait_timeout | 300 |
+-------------------------+-------+
8 rows in set (0.00 sec)之后我的疑惑: 为什么 show processlist 中 time 列还有超过300秒的sleep进程?????mysql> show processlist;
+----------+----------------+---------------------+----------+-------------+---------+----------------------------------------------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----------+----------------+---------------------+----------+-------------+---------+----------------------------------------------------------------+------------------+
| 2 | aa | 192.168.1.81:36831 | NULL | Binlog Dump | 2362827 | Has sent all binlog to slave; waiting for binlog to be updated | NULL
| 4868501 | aa | 192.168.1.129:37854 | NULL | Binlog Dump | 515107 | Has sent all binlog to slave; waiting for binlog to be updated | NULL
| 12600468 | abc_admin | 192.168.1.116:25271 | abc | Sleep | 7399 | | NULL
| 12608033 | abc_admin | 192.168.1.116:27573 | abc | Sleep | 7306 | | NULL
| 12624454 | abc_admin | 192.168.1.116:33785 | abc | Sleep | 6174 | | NULL
| 12626744 | abc_admin | 192.168.1.116:34358 | abc | Sleep | 6626 | | NULL
| 12642032 | abc_admin | 192.168.1.116:39647 | abc | Sleep | 6108 | | NULL
| 12654395 | abc_admin | 192.168.1.116:44124 | abc | Sleep | 3805 | | NULL
| 12698547 | abc_admin | 192.168.1.116:61930 | abc | Sleep | 3745 | | NULL
MySQL中的配置参数interactive_timeout和wait_timeout
MySQL服务器所支持的最大连接数是有上限的,因为每个连接的建立都会消耗内存,因此我们希望客户端在连接到MySQL Server处理完相应的操作后,应该断开连接并释放占用的内存。如果你的MySQL Server有大量的闲置连接,他们不仅会白白消耗内存,而且如果连接一直在累加而不断开,最终肯定会达到MySQL Server的连接上限数,这会报'too many connections'的错误。对于wait_timeout的值设定,应该根据系统的运行情况来判断。在系统运行一段时间后,可以通过show processlist命令查看当前系统的连接状态,如果发现有大量的sleep状态的连接进程,则说明该参数设置的过大,可以进行适当的调整小些。我按照这个提示 操作如下
mysql> show variables like '%timeout%';
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| interactive_timeout | 28800 |
| net_read_timeout | 30 |
| net_write_timeout | 60 |
| slave_net_timeout | 3600 |
| table_lock_wait_timeout | 50 |
| wait_timeout | 28800 |
+-------------------------+-------+
8 rows in set (0.00 sec)mysql> set global wait_timeout=300 ,interactive_timeout=300;退出 重新登录。。mysql> show variables like '%timeout%';
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| interactive_timeout | 300 |
| net_read_timeout | 30 |
| net_write_timeout | 60 |
| slave_net_timeout | 3600 |
| table_lock_wait_timeout | 50 |
| wait_timeout | 300 |
+-------------------------+-------+
8 rows in set (0.00 sec)之后我的疑惑: 为什么 show processlist 中 time 列还有超过300秒的sleep进程?????mysql> show processlist;
+----------+----------------+---------------------+----------+-------------+---------+----------------------------------------------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----------+----------------+---------------------+----------+-------------+---------+----------------------------------------------------------------+------------------+
| 2 | aa | 192.168.1.81:36831 | NULL | Binlog Dump | 2362827 | Has sent all binlog to slave; waiting for binlog to be updated | NULL
| 4868501 | aa | 192.168.1.129:37854 | NULL | Binlog Dump | 515107 | Has sent all binlog to slave; waiting for binlog to be updated | NULL
| 12600468 | abc_admin | 192.168.1.116:25271 | abc | Sleep | 7399 | | NULL
| 12608033 | abc_admin | 192.168.1.116:27573 | abc | Sleep | 7306 | | NULL
| 12624454 | abc_admin | 192.168.1.116:33785 | abc | Sleep | 6174 | | NULL
| 12626744 | abc_admin | 192.168.1.116:34358 | abc | Sleep | 6626 | | NULL
| 12642032 | abc_admin | 192.168.1.116:39647 | abc | Sleep | 6108 | | NULL
| 12654395 | abc_admin | 192.168.1.116:44124 | abc | Sleep | 3805 | | NULL
| 12698547 | abc_admin | 192.168.1.116:61930 | abc | Sleep | 3745 | | NULL
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