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What is sleep connection in MySQL?
A sleeping MySQL query is an inactive open connection. When too many exist at the same time, the MySQL server will run out of connections, causing the server to be unable to process queries. However, blindly killing sleeping queries can have bad results, such as database corruption or data loss.
What happens if MySQL connection is not closed?
4 Answers. It will automatically close when the PHP script is done running during destruct phase. Performance will negatively be affected. Opening a new socket (especially to an external database server) is more expensive and time consuming than just keeping a pointer to the current connection in memory.
How do I see sleep connections in MySQL?
In short using the following (or within my. cnf) will remove the timeout issue. SET GLOBAL interactive_timeout = 180; SET GLOBAL wait_timeout = 180; This allows the connections to end if they remain in a sleep State for 3 minutes (or whatever you define).
Why are MySQL connections still in ” sleep ” state?
Using this feature, PHP does not disconnect from the server after every request served, but keeps the connections for future requests. When not used, these connections are in a “sleep” state, as can be seen with “mysqladmin processlist”.
Is there a problem with too many connections to MySQL?
That never was much of a problem (and I didn’t find a quick solution) until recently traffic numbers increased and since then MySQL reports the “to many connections” Problems repeatedly, even so 350+ of those connections are in “sleep” state. Also a server can’t get a MySQL connection even if there are sleeping connection to that same server.
When does a connection get closed in MySQL?
They occur when a connection is requested, but is not closed- the connection is still reserved by that thread and “waiting for the client to send a new statement to it”. If the sleep time of a thread exceeds the wait_timeout variable for mysql, the connection gets closed and recycled.
Why are MySQL connections disappearing when Apache restates?
Also a server can’t get a MySQL connection even if there are sleeping connection to that same server. All those connections vanish when an apache server is restated. The PHP Code used to create the Database connections uses the normal “mysql” Module, the “mysqli” Module, PEAR::DB and Zend Framework Db Adapter. (Different projects).