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From:Claudio Nanni Date:February 25 2010 11:28pm
Subject:Re: What is "unusually high" for the # of connections to MySQL?
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It depends, but 100 is not strange at all, particularly if you have sleeping
(usually due to slow page loading (ajax?) and/or persistent connections from
the app)
and any number of connections cannot crash a server, can make it slow or
unusable, but not crash it.
Watch the app, you could have for loops banging the database, a not
optimized app can kill cause a D.O.S.(=bad) of MySQL.

Anyway the point is another.
I think you cant afford guessing, it will take a huge amount of effort to
try to guess why it crashes.
Find the more information you can enabling all the logging possible, put
server parameters under graphing,
the more information you have on the crash, the less you will need to guess.
Watch, cpu(load, context switches), ram(usage,swapping), IO.

Guess less, know more.


2010/2/26 Jesse <jc@stripped>

> I was wondering what would be considered "unusually high" for the # of
> connections to a MySQL Server?  Also, if a high number of these are in
> "sleep" mode,does it make a difference?
> We have a web site (a few, actually) and MySQL (Version
> 5.0.67-community-nt-log)  running on a WS08 server, and several times now,
> we have basically had the web site "crash" on us.  One tech thought that it
> may be the # of connections.  I have seen between 100 to 125 connections or
> so at one time 98% of them all from the same user. This is from our
> web application that we're using for testing. The app basically
> becomes unresponsive, but I'm not 100% convinced that this is a MySQL
> problem.  The site does not even seem to be serving up pages when it gets
> into this "mode".
> Also, there are other web sites on this same server (not being used a lot
> at all), and these sites all seem to come up just fine. There are no
> connection issues with the pages or with the data in those applications.
> My main questio is this.  Is 100 to 125 unusually high?  I have implemented
> a connection pool into my connection string in hopes that this will resolve
> the problem.  Here is that string:
> uid=usernamer;password=password;Server=;port=3306;Database=mydatabase;Allow
> Zero Datetime=true;pooling=true; max pool size=10; min pool size=3
> Someone else suggested this string, but after implementing it and
> re-starting the server, we still had the same problem.  My plan is to move
> the app to a WS03 server tonight in hopes that the issue is the O/S.
> Can anyone fill me in?
> Thanks,
> Jesse
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What is "unusually high" for the # of connections to MySQL?Jesse26 Feb
  • Re: What is "unusually high" for the # of connections to MySQL?Claudio Nanni26 Feb
  • Re: What is "unusually high" for the # of connections to MySQL?Jesse26 Feb
    • Re: Re: What is "unusually high" for the # of connections to MySQL?claudio.nanni26 Feb
      • Re: Re: What is "unusually high" for the # of connections to MySQL?Ananda Kumar26 Feb