本篇内容介绍了“MySQL中参数wait_timeout和interactive_timeout以及空闲超时的实现方法是什么”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
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这里简单解释一下两个参数含义如下：
interactive_timeout：The number of seconds the server waits for activity on an interactive connection before closing
it. An interactive client is defined as a client that uses the CLIENT_INTERACTIVE option to mysql_real_connect()
wait_timeout：The number of seconds the server waits for activity on a noninteractive connection before closing it.
On thread startup, the session wait_timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect())
他们都是session/global级别的，简单的说前者用于描述交互式的客户端的空闲超时，后者用于非交互式的客户端的空闲超时，但是这里也揭示了，如果是交互式客户端连接的session那么wait_timeout将被interactive_timeout覆盖掉，换句话说如果是非交互式的客户端连接的session将不会使用interactive_timeout覆盖掉wait_timeout，也就是interactive_timeout没有任何作用了。
interactive_timeout：
static Sys_var_ulong Sys_interactive_timeout( vio_io_wait "interactive_timeout", "The number of seconds the server waits for activity on an interactive " "connection before closing it", SESSION_VAR(net_interactive_timeout), CMD_LINE(REQUIRED_ARG), VALID_RANGE(1, LONG_TIMEOUT), DEFAULT(NET_WAIT_TIMEOUT), BLOCK_SIZE(1));
wait_timeout：
static Sys_var_ulong Sys_net_wait_timeout( "wait_timeout", "The number of seconds the server waits for activity on a " "connection before closing it", SESSION_VAR(net_wait_timeout), CMD_LINE(REQUIRED_ARG), VALID_RANGE(1, IF_WIN(INT_MAX32/1000, LONG_TIMEOUT)), DEFAULT(NET_WAIT_TIMEOUT), BLOCK_SIZE(1));
我们可以看到内部而言参数interactive_timeout表示为net_interactive_timeout，wait_timeout表示为net_wait_timeout。
实际上这个操作只会在用户登陆的时候才出现函数对应server_mpvio_update_thd，如下：
server_mpvio_update_thd(THD *thd, MPVIO_EXT *mpvio) do_command
{
thd->max_client_packet_length= mpvio->max_client_packet_length; if (mpvio->protocol->has_client_capability(CLIENT_INTERACTIVE)) //这里做判断
thd->variables.net_wait_timeout= thd->variables.net_interactive_timeout;//这里覆盖这里我们可以明确看到有覆盖操作，并且我们也能看到这里的if条件是如果是CLIENT_INTERACTIVE类型的客户端连接才会做覆盖。
栈帧如下：
#0 server_mpvio_update_thd (thd=0x7ffe7c012940, mpvio=0x7fffec0f6140) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/auth/sql_authentication.cc:2014#1 0x0000000000f01787 in acl_authenticate (thd=0x7ffe7c012940, command=COM_CONNECT, extra_port_connection=false) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/auth/sql_authentication.cc:2246#2 0x0000000001571149 in check_connection (thd=0x7ffe7c012940, extra_port_connection=false) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/sql_connect.cc:1295#3 0x00000000015712dc in login_connection (thd=0x7ffe7c012940, extra_port_connection=false) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/sql_connect.cc:1352#4 0x0000000001571bfe in thd_prepare_connection (thd=0x7ffe7c012940, extra_port_connection=false) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/sql_connect.cc:1516#5 0x000000000170e642 in handle_connection (arg=0x6781c30) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/conn_handler/connection_handler_per_thread.cc:306
那么我们这里可以得到一个结论，只在登陆的时候会判断连接是否是交互式的，如果是则覆盖掉参数wait_timeout，但是一旦连接后将不会发生覆盖操作，即便我们再次修改interactive_timeout的值也不会覆盖，后面我们会看到实际上生效的参数只有wait_timeout。
实际上每次执行任何一个命令都会做一次wait_timeout值的重新检查和赋值给网络read_timeout值。在函数do_command中我们可以发现my_net_set_read_timeout(net, thd->get_wait_timeout());步骤，这个步骤就是将我们的wait_timeout赋值给网络read_timeout值，其中包含片段
if (net->read_timeout == timeout) //如果read_timeout和wait_timeout相等 DBUG_VOID_RETURN;//不需要做操作直接return net->read_timeout= timeout;//否则进行赋值。 if (net->vio) vio_timeout(net->vio, 0, timeout);//这里会进行net->vio.read_timeout的赋值
执行完这个步骤后wait_timeout就生效了，然后就会执行命令，执行完命令后，整个线程会再次回到do_command函数，再做一次my_net_set_read_timeout函数生效其中的wait_timeout参数，中并且堵塞接受命令(后面可以看到是poll实现的)，这个时候wait_timeout就起作用了。整个栈帧如下：
#0 vio_io_wait (vio=0x7ffe7c015520, event=VIO_IO_EVENT_READ, timeout=10000) at /root/mysqlall/percona-server-locks-detail-5.7.22/vio/viosocket.c:1119#1 0x0000000001e4d5f6 in vio_socket_io_wait (vio=0x7ffe7c015520, event=VIO_IO_EVENT_READ) at /root/mysqlall/percona-server-locks-detail-5.7.22/vio/viosocket.c:116#2 0x0000000001e4d6d2 in vio_read (vio=0x7ffe7c015520, buf=0x7ffe7c061c10 "\001", size=4) at /root/mysqlall/percona-server-locks-detail-5.7.22/vio/viosocket.c:171#3 0x00000000014c6ceb in net_read_raw_loop (net=0x7ffe7c028440, count=4) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/net_serv.cc:672#4 0x00000000014c6ec2 in net_read_packet_header (net=0x7ffe7c028440) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/net_serv.cc:756#5 0x00000000014c6fcb in net_read_packet (net=0x7ffe7c028440, complen=0x7fffec0c5c58) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/net_serv.cc:822#6 0x00000000014c715e in my_net_read (net=0x7ffe7c028440) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/net_serv.cc:899#7 0x00000000014de010 in Protocol_classic::read_packet (this=0x7ffe7c027bf8) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/protocol_classic.cc:808#8 0x00000000014de514 in Protocol_classic::get_command (this=0x7ffe7c027bf8, com_data=0x7fffec0c5d70, cmd=0x7fffec0c5d98) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/protocol_classic.cc:965#9 0x00000000015c5699 in do_command (thd=0x7ffe7c0268e0) at /root/mysqlall/percona-server-locks-detail-5.7.22/sql/sql_parse.cc:960
最终会调入vio_io_wait函数，如下是其中的部分片段，我们可以清楚看到实际上所谓的空闲超时实际上就是我们的pool实现的。
switch ((ret= poll(&pfd, 1, timeout)))
{ case -1: /* On error, -1 is returned. */
break; case 0: /*
Set errno to indicate a timeout error.
(This is not compiled in on WIN32.)
*/
errno= SOCKET_ETIMEDOUT; break; default: /* Ensure that the requested I/O event has completed. */
DBUG_ASSERT(pfd.revents & revents); break;
}因此整个步骤就是
loop
做wait_timeout参数检查并且赋值。
堵塞接受命令由poll函数实现，通过poll函数的超时参数也实现了空闲等待超时。(如果不发送命令就堵塞在这里)
命令来到退出堵塞。
再次做wait_timeout参数检查并且赋值。
执行命令。
goto loop
我这里就用mysql客户端和pymysql进行交互和非交互连接的测试。
交互式mysql客户端会话interactive_timeout 参数覆盖wait_timeout参数
mysql> show variables like 'wait_timeout%'; +---------------+-------+| Variable_name | Value | +---------------+-------+ | wait_timeout | 28800 |+---------------+-------+1 row in set (0.02 sec) mysql> show variables like 'interactive_timeout'; +---------------------+-------+| Variable_name | Value | +---------------------+-------+ | interactive_timeout | 28800 |+---------------------+-------+1 row in set (0.01 sec) mysql> set global interactive_timeout = 20; Query OK, 0 rows affected (0.00 sec) mysql> exit Bye [root@gp1 log]# /mysqldata/mysql3340/bin/mysqlWelcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 6Server version: 5.7.22-22-debug-log Source distribution Copyright (c) 2009-2018 Percona LLC and/or its affiliates Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show variables like 'interactive_timeout'; +---------------------+-------+| Variable_name | Value | +---------------------+-------+ | interactive_timeout | 20 |+---------------------+-------+1 row in set (0.01 sec) mysql> show variables like 'wait_timeout'; +---------------+-------+| Variable_name | Value | +---------------+-------+ | wait_timeout | 20 |+---------------+-------+1 row in set (0.02 sec)
交互式mysql客户端会话登陆期间修改interactive_timeout不生效，更改wait_timeout生效。
mysql> show variables like 'interactive_timeout'; +---------------------+-------+| Variable_name | Value | +---------------------+-------+ | interactive_timeout | 28800 |+---------------------+-------+1 row in set (0.02 sec) mysql> show variables like 'wait_timeout'; +---------------+-------+| Variable_name | Value | +---------------+-------+ | wait_timeout | 28800 |+---------------+-------+1 row in set (0.02 sec) mysql> set interactive_timeout=5; Query OK, 0 rows affected (0.00 sec) mysql> show variables like 'wait_timeout'; +---------------+-------+| Variable_name | Value | +---------------+-------+ | wait_timeout | 28800 |+---------------+-------+1 row in set (0.01 sec) mysql> show variables like 'interactive_timeout'; +---------------------+-------+| Variable_name | Value | +---------------------+-------+ | interactive_timeout | 5 |+---------------------+-------+1 row in set (0.02 sec) 等待5秒，并未生效 mysql> select sysdate(); +---------------------+| sysdate() |+---------------------+| 2019-02-28 17:24:29 |+---------------------+1 row in set (0.00 sec) mysql> set wait_timeout=5; Query OK, 0 rows affected (0.00 sec) 等待5秒 发现断开了 mysql> show variables like 'wait_timeout'; ERROR 2006 (HY000): MySQL server has gone away No connection. Trying to reconnect... Connection id: 10
使用python连接非交互式客户端interactive_timeout 参数不会覆盖wait_timeout参数
我们可以简单的写一个python脚本如下：
import socketimport pymysql.cursorsimport psutilimport subprocess
mysql_con = {"host":"192.168.99.95","port":3340,"user":"pycon","passwd":"gelc123","db":"test"}def main():
sqlwait = "show variables like 'wait_timeout'"
sqlinter = "show variables like 'interactive_timeout'"
sql_c_inter = "set global interactive_timeout=10"
connect = pymysql.Connect(host=mysql_con["host"], port=mysql_con["port"], user=mysql_con["user"],
passwd=mysql_con["passwd"], db=mysql_con["db"])
cursor = connect.cursor() ##查看初始值
cursor.execute(sqlwait)
ret_wait = cursor.fetchone()
cursor.execute(sqlinter)
ret_inter = cursor.fetchone()
print("before change: {}".format(ret_wait+ret_inter)) ##更改值
cursor.execute(sql_c_inter)
connect.close()##关闭连接
##重新登陆开启连接
connect = pymysql.Connect(host=mysql_con["host"], port=mysql_con["port"], user=mysql_con["user"],
passwd=mysql_con["passwd"], db=mysql_con["db"])
cursor = connect.cursor()
cursor.execute(sqlwait)
ret_wait = cursor.fetchone()
cursor.execute(sqlinter)
ret_inter = cursor.fetchone()
print("after change: {}".format(ret_wait+ret_inter)) ##恢复值
sql_c_inter = "set global interactive_timeout=28800"
cursor.execute(sql_c_inter)
connect.close()#关闭连接##程序开始if __name__ == '__main__':
main()得到的测试结果如下：
before change: ('wait_timeout', '28800', 'interactive_timeout', '28800')
after change: ('wait_timeout', '28800', 'interactive_timeout', '10')如果是交互是客户端会话的话wait_timeout也应该是10。
“MySQL中参数wait_timeout和interactive_timeout以及空闲超时的实现方法是什么”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识可以关注创新互联网站，小编将为大家输出更多高质量的实用文章！
