[nzlug] Is anyone familiar with socat (Multipurpose relay)

[Steve Holdoway]

Sorry I don't know the answer, and I know it's not what you want, but would a milter-based solution be an option?

I know you'd still have to migrate from exim, but...

Mind you the thought of processing hundreds of emails a second sort of points me towards solaris/sparc rather than vmware (:

Steve

On Fri, 21 Sep 2007 16:28:59 +1200 (NZST)
Martin D Kealey <martin at kurahaupo.gen.nz> wrote:

> On Thu, 20 Sep 2007, Daniel Pittman wrote:
> > > This is what i have so far:
> > >
> > > socat UNIX-LISTEN:/var/run/mysqld/mysqld.sock,fork,user=mysql,group=mysql
> > > TCP4:external.mysql.host:3306
> > >
> > > But im getting connection failed in mysql client.
> >
> > ...er, just out of interest: wouldn't it be much easier to configure
> > your mysql client software to talk TCP directly rather than trying fancy
> > tricks with redirection of the Unix socket?
>
> Actually, I *seriously* have a need for this right now.
>
> And the reason is performance: with a 2.6 Linux kernel running with 2 CPUs
> under VMware you're hard pressed to establish more than a few hundred, maybe
> a thousand or so outbound TCP connections per second. Reason being the
> spin-locks around the kernel memory allocator, which sit and wait for the
> next clock tick a lot of the time.
>
> Unix sockets have no such limitation.
>
> Why do I need so many connections?
>
> Because Exim doesn't "pool" connections to database servers: each message
> runs in a separate process, indeed possibly more than one if you segregate
> inbound and outbound SMTP processing.
>
> So you're limited to only a hundred or so email messages per second, per
> server. (Those of you who know where I work will understand why I consider
> this to be a serious limitation.)
>
> At the moment I'm hanging out for Exim5, which will have a bunch of smart
> pluggable modules, and will almost certainly include database connection
> pooling. I'm not interested in debating the merits of other MTAs; I already
> know about PosfFix and QMail; they have even more serious limitations where
> I'm at.
>
> -Martin
>
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