Database Too many connections workaround

Problem: The website suddenly error, show "Too many connections ..." What is this?

Solve:

A few useful actions are listed first:

　　① mysql -u root -pEnter the password into MySQL

② show processlist; View the number of connections, you can find that there are many connections in sleep state, these are actually temporarily useless, so you can kill

　　③ show variables like "max_connections";View the maximum number of connections, which should be the same as the number of connections queried above, before too many connections is present

　　④ set GLOBAL max_connections=1000;Modify the maximum number of connections, but this is not a once and for all method, you should let it automatically kill those sleep processes.

　　⑤ show global variables like ‘wait_timeout‘;This value refers to the number of seconds that MySQL waits before closing a non-interactive connection, which defaults to 28800s

　　 ⑥ set global wait_timeout=300; Modify this value, here can be arbitrary, preferably control in a few minutes

　　 ⑦ set global interactive_timeout=500; Modify this value to indicate the number of seconds that MySQL waits before closing a connection, so that MySQL automatically shuts down those useless connections, but be aware that the connection that is being used is also turned off , so this time value should be appropriate

My workaround:

① select concat(‘KILL ‘,id,‘;‘) from information_schema.processlist where user=‘root‘; First query the connection ID to kill

② Copy the middle of thekill id; 

③ Copy the modified content back to the terminal, and then press ENTER to execute

Database Too many connections workaround