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From:Michael Dykman Date:March 28 2008 5:08pm
Subject:Re: Problems with unauthenticated user and DB slowing down
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2008/3/28 Aleksandar Skodric <aleksandar@stripped>:
> Hi all,
>  I am having problems with the following issue.
>  Since couple of days ago, we got signs from our customers that website
>  'feels' very slow.
>  One of our tests is IQ test. For this one, timing is crucial and it is
>  unacceptable that test takes longer (because of slow site) - as it working
>  as a disadvantage for the one who is taking test.
>  We have following configuration:
>  Load balancer
>  |                  |
>  www1         www2
>  Both www1 and www2 are same hardware. On both is apache, with mysql:
>  www1:~# mysql --help
>  mysql  Ver 14.12 Distrib 5.0.32, for pc-linux-gnu (i486) using readline 5.2
>  www1 = master DB;
>  www2 = slave DB;
>  What I have noticed is that DB goes slow, there are few, sometimes many
>  (20+) unauthenticated user in process list.
>  They hang there for couple of seconds, then disappear. They are in state of
>  'connecting' and with action 'login'. They never establish connection
>  however.
>  I have checked:
>  1. ddos (could not find anything to point that way);
>  2. DNS resolving (as Google pointed that to be an issue); - no DNS problems,
>  both server can resolve nice and fast. I have also started both DB servers
>  with --skip-resolving but again, it did not help.
>  So, when these unauthenticated users come - the whole database goes real
>  slow for a few moments.
>  Has anyone had these issues? Any tips?

I don't know why the system should slow down on a few connection
attempts, but it it possible that your mysql port (3306) is open to
the outside world?  Normal pratice suggests that those ports should be
locked down so they will only accept connections from your web servers
or other internal systems.  The outside world should not even know
that they are there.

 - michael dykman
 - mdykman@stripped

 - All models are wrong. Some models are useful.
Problems with unauthenticated user and DB slowing downAleksandar Skodric28 Mar
  • Re: Problems with unauthenticated user and DB slowing downMichael Dykman28 Mar