<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Daniel,<br>
<br>
A cron job sounds like a good idea to me too.<br>
<br>
As part of a project I'm working on, I'll be developing an in-memory
cache for Nginx. I'll let you know when it's stable, in case you'd
like to try it out.<br>
<br>
Wrt VPS's, have you looked at Open VZ (i.e. Virtuozzo) VPS ISPs? I'm
currently using Tektonic, and have generally been happy with the speed
of their system. For your money, you will typically get more memory
too. The reason is to do with the platform, I believe. I think that
Xen doesn't allow dynamic changing of memory size, but VZ does - so you
can 'burst' your memory to your needs on VZ, whilst still having a
minimum level. I know that Open VZ does have some problems that I
don't think Xen does, though (e.g. with memory-mapped files, meaning
that Varnish Cache can't - currently - work on Open VZ VPSs).<br>
<br>
The difference in architecture between Xen and Open VZ might mean that
you'd get a better IO performance on that (I think I was getting more
than 5000 req/s serving static files on my $15/mo VPS).<br>
<br>
Just something you might want to look at.<br>
<br>
Marcus.<br>
<br>
<br>
Atif Ghaffar wrote:
<blockquote
cite="mid:f240b640903051350o2e89608o5f0cafec74df0e91@mail.gmail.com"
type="cite">Daniel,<br>
I see this as a good compromise for your situation.<br>
<br>
<div class="gmail_quote">On Thu, Mar 5, 2009 at 9:36 PM, Daniel
Rhoden <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:drhoden@gmail.com">drhoden@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="">There has been a growing trend in using VPS like Xen
to host sites. What I'm seeing is that memory is guaranteed, but the
I/O to the hard drive is competing with the other customers on the same
physical server.
<div><br>
</div>
<div>I've given up on the idea of using Perl to populate memcached
on the fly for anything, static html or dynamic. I agree that the best
place for memory caching of static content is right with nginx.</div>
<div><br>
</div>
<div>Did some analysis and found that about 1% of our pages get 40%
of the traffic. Since these are static pages it is unlikely that they
will change in popularity from day to day. So I've decided that a cron
job can populate the cache for these few pages (and then some) with
very little overhead, very little memory, with the biggest payoff.</div>
<div><br>
</div>
<div>Thank you all for your feedback on this idea. </div>
<div><br>
</div>
<div>By the way: I am seeing a boost in performance by caching
static files. Small, but every ms counts.</div>
<div>
<div class="h5">
<div><br>
<div>
<div>On Mar 5, 2009, at 1:09 PM, Marcus Clyne wrote:</div>
<br>
<blockquote type="cite">
<div bgcolor="#ffffff" text="#000000"> Atif,<br>
<br>
I understood it the same way you did, and was saying that serving files
from memcached as opposed to the filesystem has negligible benefits,
and sometimes actually performs worse.<br>
<br>
The reference to error_page (not error_file as I said before - memory
slip) was just as a means to populate memcache when there's no data in
the cache - you could easily use this method to put the file into
memcache from the filesystem. You wouldn't need to use an Nginx module
to put the file into memcache (at least not with the current Perl
module - it's blocking, so would slow everything down too much, though
with a non-blocking version it could be ok) - though I understand that
that's what he's talking about and where he's talking about hooking it
in.<br>
<br>
Another method would be to use the try_files directive.<br>
<br>
Overall, though, I can only see populating memcache with a file to
serve through Nginx as being overall slower than serving the file from
the filesystem. In my tests, memcache vs filesystem is pretty similar,
and adding any kind of overhead to put a file in memcache will mean
just serving the file statically will be more efficient (and won't
waste memory unnecessarily). I could see storing static files in an
internal memory cache being a bit quicker than serving files
statically, but actually not all that much, and would only possibly be
of real benefit for files that are under very high demand (e.g. a
homepage or a logo on a high-traffic site).<br>
<br>
Cheers,<br>
<br>
Marcus.<br>
<br>
<br>
Given that the<br>
<br>
Atif Ghaffar wrote:
<blockquote type="cite"><br>
<br>
<div class="gmail_quote">On Thu, Mar 5, 2009 at 12:34 PM,
Marcus Clyne <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:eugaia@gmail.com" target="_blank">eugaia@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"><br>
For populating the cache, have you looked at the error_file directive.
You can set the error file to script which could be passed to an FCGI
process, so that on a cache-miss the script is called to generate the
page, which could in the process put the file into the memcached
cache. </div>
</blockquote>
<div><br>
Marcus, <br>
<br>
I believe Daniel was talking about the opposite. He want to populate
the cache if nginx hits the file instead of when it does not find it.<br>
<br>
So something like this (this is how nginx would do it<br>
<br>
request comes from /files/1.txt<br>
1. Check if memcache exists and serve from there.<br>
2. Check if file exist and serve from here. <---- This is where he
wants to hook it :-)<br>
3. If file does not exists, handle error.<br>
<br>
What Daniel wants (if I understood correctly)<br>
request comes from /files/1.txt<br>
1. Check if memcache exists and serve from there.<br>
2. if(-f file ) call the perl/fcgi process that populates the memcache
cache and returns the file. (so this would be done only where there is
no cache in memcache)<br>
3. If file does not exists, handle error.<br>
<br>
<br>
Still I dont see whats the point of this but yes it is doable.<br>
<br>
best regards<br>
<br>
<br>
<br>
<br>
<br>
</div>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000">This of course only
really makes sense for dynamically-generate content.<br>
<font color="#888888"><br>
Marcus.</font>
<div>
<div><br>
<br>
<br>
Atif Ghaffar wrote:
<blockquote type="cite">Daniel, <br>
<br>
I see now your other posts, <br>
<br>
I do not think that you will get any benifit of using memcached with
static files.<br>
Nginx is already very optimized at serving static files.<br>
<br>
<br>
<div class="gmail_quote">On Wed, Mar 4, 2009 at 11:17 PM,
Daniel Rhoden <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:drhoden@iiwinc.com" target="_blank">drhoden@iiwinc.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">This
is purely speculative, so please don't think I know how to do this.
I'm throwing this out so hopefully, if a good idea, the right people
can create the example.<br>
<br>
Memcached has a good assortment of Perl clients.<br>
<br>
Nginx has a means of embedding Perl into the configuration.<br>
<br>
Couldn't there be a way of combining these to immediately populate the
cache when the cache returns missing?<br>
<br>
By the way, I'm looking at this as a means of improving I/O for static
pages (on SliceHost). Ideally nginx's Memcached Module would have the
ability to do this when the requested filename exists on the hard drive:<br>
(-f $request_filename/index.html)<br>
<font color="#888888"><br>
<br>
Daniel Rhoden<br>
Director of Information Technology<br>
Interactive Internet Websites, Inc.<br>
3854 - 2 Killearn Court<br>
Tallahassee, Florida 32309<br>
Voice: (256) 878-5554<br>
E-Mail: <a moz-do-not-send="true" href="mailto:drhoden@iiwinc.com"
target="_blank">drhoden@iiwinc.com</a><br>
Website: <a moz-do-not-send="true" href="http://iiwinc.com"
target="_blank">iiwinc.com</a><br>
<br>
<br>
</font></blockquote>
</div>
<br>
<br clear="all">
<br>
-- <br>
best regards<br>
Atif Ghaffar<br>
</blockquote>
<br>
</div>
</div>
</div>
</blockquote>
</div>
<br>
<br clear="all">
<br>
-- <br>
best regards<br>
Atif Ghaffar<br>
</blockquote>
<br>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</div>
</div>
</blockquote>
</div>
<br>
<br clear="all">
<br>
-- <br>
best regards<br>
Atif Ghaffar<br>
</blockquote>
<br>
</body>
</html>