"For example, if you ssh to them, the login prompt appears quickly, but
after you enter the user name it may be 10 seconds before the password
prompt appears."

That sounds like there is something timing out.  It doesn't sound like
MySQL is your issue.  I'd be curious to know more about how this
machine authenticates people, and how it's acting on the network
(i.e., does it have a DNS server, and can it ping it/resolve host
names).

"Oddly enough, when I had this same problem it was traced back to the
fact that our server could not reach our nameserver."

All the more reason to look into DNS.

On 5/12/05, Bill Earl <bearl@bestbill.com> wrote:
> 
> Alex Dean wrote:
> 
> > 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.
> 
> I agree, obviously something changed, but I don't see any signs that
> anything changed. No one was here at the time the connection slowdown
> started (I don't know when it was exactly; it wasn't this way yesterday
> afternoon and it is this morning).
> 
> >    * 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.
> 
> I've since found a third internal machine (also a SuSE machine, btw, but
> 9.0) exhibiting the same behavior that started this morning. This
> machine has apache running and an app that connects to mysql on that
> machine, and the web performance is speedy. However, just logging in by
> ssh is slow (as it is on all the machines).
> 
> >    * 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.)
> 
> Yep.  Most of the time, no users are connected. I get the slow initial
> response being the only one attempting to connect.
> 
> >    * 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.
> 
> No.
> 
> 
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