Re: very slow initial connection, then all is well

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Author: Alex Dean
Date:  
To: plug-discuss
Subject: Re: very slow initial connection, then all is well
Bill Earl wrote:

> It seems to just be something with that initial connection, whether
> it's through ssh or mysql. Viewing the process list and top while
> logging in from another system doesn't show anything starting up or
> using a lot of cpu time.
>
> Does anyone have any suggestions on what to check? This started
> sometime overnight, and all the normal nighttime processes completed
> okay with no errors. They're on an internal network, not exposed to
> the Internet, so I don't suspect an intrusion.


    * What changed overnight?  Did someone update ssh, mysqld, mysql
      client, change mysql config settings, etc?  If this is a new
      occurrence, then something must have changed.  If you can figure
      out what it was, you'll have your answer.
    * What happens when/if you connect to mysql via some other method
      (like a PHP or Perl script)?  If you get the same long pause, then
      it's probably something internal to mysqld.  If the script can
      connect instantly, it's probably in the mysql client program or in
      ssh.
    * Can you monitor how many users are connected to the db server at
      once?  Maybe you have a limit there.  (To see your limit, do "SHOW
      VARIABLES LIKE 'max_connections'".  It might be interesting to
      just do "SHOW VARIABLES" and look for anything which seems odd.)
    * Do you have any queries which lock the 'mysql' database or any of
      its tables?  If so, all other users would have to wait until the
      lock is released to authenticate/connect.



alex
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