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From:mos Date:October 30 2008 5:05am
Subject:Re: "lost connection to mysql server during query" errors
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At 10:21 PM 10/29/2008, you wrote:
>I've never had a lot of luck tracking down this sort of problem. One
>thing I've found to be a good first step is to add each server
>involved to the other server's /etc/hosts file (and restart MySQL so
>it notices).
>Don't have much more to offer other than the usual suspects: recent
>versions, persistent vs. non-persistent connections, etc. A long shot
>would be to make sure your always talking to the same database server-
>if you're doing, say, DNS round-robin or load balancing or something,
>maybe you're getting shunted to a different db server and it's killing
>the connection... don't know what your setup is. Another long shot in
>a multi-db-server config would be to make sure they all have different
>server ID's.
>Good luck... hopefully someone else has better advice :)

Just a guess, but maybe it's your network card?

I'm using MySQL 5.01 with MyISAM tables and my application will 
occasionally hang for hours in the midst of executing a simple 1 table 
Select statement. I usually end up killing the program. There are no 
processes running on the MySQL server. I think the problem was the number 
of connections the program created. Although there were only at most 10 
simultaneous connections, my program when the query finished executing, it 
threw the connection away and recreated a new one for each query, and MySQL 
reported there were some 10k connections made to the server. I ended up 
using connection pooling and now the number of connections reaches a high 
of around 10 and I haven't had the problem since.


>On Wed, Oct 29, 2008 at 2:47 AM, Waynn Lue <waynnlue@stripped> wrote:
> > We've started seeing mysql errors in the logs, and when i look at the 
> output
> > of mysql_error() (in php), i get "lost connection to mysql server during
> > query". Here's an example stack trace:
> >
> > 'Can't connect to <name> database [Lost connection to MySQL server during
> > query]'
> >
> > Similarly, we're seeing stack traces here as well:
> >
> > 'Can't connect to <name> database []'
> >
> > I usually only see this mesasge when I don't use a connection for 
> awhile and
> > it timeouts, but in this case, the connection is only opened for the
> > duration of a script, which can't be running for more than a second. The
> > mysql error logs don't show anything, and wait_timeout is set to 28800.
> >
> > At first, I thought it was because I was calling mysql_select_db too much,
> > so I ended up using two mysql connections per page load, but that didn't
> > seem to change anything. How can we prevent this error from happening, what
> > else can I do to diagnose this further?  Google brings up some more
> > discussions about it, but nothing seems related to this, like packetsize.
> > This is happening when we select two ids from a database.  And SHOW
> > PROCESSLIST shows that the number of connections aren't even coming 
> close to
> > max connections.
> >
> > Thanks for any advice,
> > Waynn
> >
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"lost connection to mysql server during query" errorsWaynn Lue29 Oct
  • Re: "lost connection to mysql server during query" errorsJake Maul30 Oct
    • Re: "lost connection to mysql server during query" errorsmos30 Oct
      • Re: "lost connection to mysql server during query" errorsMoon's Father31 Oct