Re: question about 3sec timeouts with tcp

[Gabriel Barazer]

On 04/01/2008 11:30:43 PM +0200, Bernd Eckenfels <ecki@xxxxxxxxxxxx> wrote:
> In article <47F29777.6020400@xxxxxxxx> you wrote:
> >  I'm not sure what do you mean by "mass produce" connections, but even 
> > with only 200 connections/sec to the mysql-server the delay occured.
>
> Just an unrelated question: why dont you use a connection pool in this
> scenario. With Oracle for example that would totally break down, a typical
> connect takes 80-130ms with Oracle on *ix.

[off-topic]

There is a very good reason, and the Oracle example you give is the one 
I use for comparison when I am asked this. You are far from being the 
first one to ask this very legit question :)

MySQL compared to Oracle has a _very_ low connection overhead by design 
(~1ms), and also opposed to Oracle, has weaknesses to manage high number 
of permanent connections (mainly because of the memory management). 
Besides, there are several cons using the same connection: transactions 
not properly reset, latent session-level variables, etc. and other 
MySQL-specific features. You can't really have a "clean" environment 
when using an already used connection thread with MySQL.

This is also why MySQL became so popular among web/php programmers: 
because the concept of connecting/querying/closing a mysql resource in 
the same script is very easy to understand (and the only way to do with 
CGI scripts) and MySQL makes it viable thanks to its low connection 
overhead.

This article may be of interest for further information:
http://www.mysql.com/news-and-events/newsletter/2002-11/a0000000086.html

[/off-topic]

Back to the topic :)

Gabriel
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