SHOW PROCESSLIST in MySQL command: sleep

Question

When I run SHOW PROCESSLIST in MySQL database, I get this output:

mysql> show full processlist;  +--------+------+-----------+--------+---------+-------+-------+-----------------------+ | Id     | User | Host      | db     | Command | Time  | State | Info                  | +--------+------+-----------+-------+---------+-------+-------+-----------------------+ | 411665 | root | localhost | somedb | Sleep   | 11388 |       | NULL                  |  | 412109 | root | localhost | somedb | Query   |     0 | NULL  | show full processlist |  +--------+------+-----------+-------+---------+-------+-------+------------------------+ 

I would like to know the process "Sleep" that is under Command. What does it mean? Why it is running since a long time and showing NULL? It is making the database slow and when I kill the process, then it works normally. Please help me.

Answer 1

It's not a query waiting for connection; it's a connection pointer waiting for the timeout to terminate.

It doesn't have an impact on performance. The only thing it's using is a few bytes as every connection does.

The really worst case: It's using one connection of your pool; If you would connect multiple times via console client and just close the client without closing the connection, you could use up all your connections and have to wait for the timeout to be able to connect again... but this is highly unlikely :-)

See MySql Proccesslist filled with "Sleep" Entries leading to "Too many Connections"? and https://dba.stackexchange.com/questions/1558/how-long-is-too-long-for-mysql-connections-to-sleep for more information.