Connections dropped under load

[Kristian Lyngstol]

On Tue, Jan 11, 2011 at 11:35:42AM +0100, George Georgovassilis wrote:
> Personally I'm cool with either way of posting, a quick scan of the
> mail archives showed that both were being practised and I couldn't
> find any posting rules in the maillist desc - so (even at the risk
> that you do mind) I'll stay with top posting... the modern internet
> has evolved past this discussion [1] and I really can't be bothered.

It is true that this isn't explicitly documented, yet top-posting is not
preferred on the Varnish lists. That it is not documented anywhere doesn't
change that - it only means that you get the first offence for free. It
wasn't my intention to berate you, but I would like the mail to this list
to be of the traditional mail list type.

The reason is simple: I often keep up with 5-6 threads of communication on
the very same list. To be able to accomplish that, it's a great help if I
have some context to deal with when you are writing. It's not much to ask
for.

If you continue to top post even after being hinted that you should not,
you are essentially being rude to the people who would help you. It's true
that others top-post too, but that's not an excuse for you to continue
doing so. The reality is that top-posting leads to less focused replies,
missed questions and eventually a departure of some of the most experienced
users and developers from the mail lists because we don't want to cope with
it. And eventually you end up with the blind leading the blind.

It's a difference of ego: Top-posting might be easier to write, but it is
by far harder to read on a busy mail list. If you can't be bothered to
invest time in writing your mail, why should I be bothered to read it - let
alone answer you.

As for whatever arguments exist FOR top-posting, I really do not care. In
my experience, the people who top-post and continue to do so are the
members of the community that are least willing to truly contribute in a
positive manner. I usually assume that top-posting is based on ignorance,
not malice, but continued top-posting can't be seen as anything but malice.

> Please also note that in no way the Varnish documentation (see
> chapter on prerequisites [2]) mentions a high-end server for even
> moderate loads (I iterate: we are talking here about lousy 700
> req/s), and keep in mind that this discussion has turned to a
> "virtual" resource: it's not about memory or CPU power but a logical
> division of such, namely threads. I do take the point however that
> when it comes to scalability nginx might be a better choice [3].

Simply put: If your virtual solution limits your usage of threads, then
picked the wrong virtual solution to run Varnish on.

If you take a look at the architecture notes[1], you'll see what I'm
talking about. Varnish is designed for high-end servers and environments,
but works just fine under low-end systems too. I'm fairly sure my mail
didn't say anything about requiring high-end hardware, but I don't really
know, since your quoting style doesn't let me easily check what precisely
you are replying to. I suspect you are just being inaccurate in your
response. Rest assure that I catch details for better or worse - and I use
them in my replies. If I say it's designed for high-end hardware, that does
NOT mean that high-end hardware is required. You don't have to run just
because you are wearing running shoes.

However, limiting the number of threads is not something that is strongly
affected by hardware at all. And there are many virtual environments
that will have no trouble at all using threads heavily. That puts your
particular environment into what I like to call the "Nintendo"-category:
It's not a real platform anymore and if it works, then that's fun and nice
and all of that, but if it doesn't, it's not something that we should
divert resources to.

That you did not state up-front that this was a virtual environment which
put artificial limits on thread-usage is regrettable, but not a big deal.
In that regard, I'm more worried about all the people who tried to help you
without querying for those rather important (and easily available) details.

This will be the last reply I send to you if you keep top posting. Your
choice.

[1] http://www.varnish-cache.org/trac/wiki/ArchitectNotes

- Kristian