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Anyway, I wanted to link the slides from my Plack basics talk.

Thanks to Miyagawa, who's 2010 talk I based it on and to Alex and Damian who's speaker training helped me refine what I'd done even further.

It was really encouraging to have so many people afterwards come up and say they were either going to start using Plack or could now see using it even more.

I hope that that talk was recorded and a video will be available, and if not I'll try do my own recording soon.

Today, a bit more with it, acme, ralf, Michael and myself had a stroll around the main market - housed in old Zeppelin hangers! - which was interesting and had very tasty donuts, and a general look around the old town.

I then attended the Speakers training run by Alex Kapranov with Damian Conway also speaking. It was really interesting and now means I have to update my slides (thankfully not too much)!

I showed once section of my presentation and got some really useful feedback (come to my Plack talk if you want to see the changes in action!)

If you ever get a chance to go to this Speaker training I really recommend it, how ever many talks your already done.

Then we headed to the main square again for a pre pre social social, there was some food, and some beer, then more people, then it was officially the pre social and more people, then some beer and some more people. It's really nice catching up with everyone, some of which I've not seen for several years, and some of which I've not seen since that last YAPC::EU, but it's also nice seeing new faces (hopefully I'll get to meet more people as the conference progresses).

I'm really looking forward to the next few days.

We thought if only there was a quick way to cache the results as we develop the code...

A CPAN search later... we want a proxy and something to cache

use Plack::Builder;
use Plack::App::Proxy;
use Plack::Middleware::Cache;

my $app
    = Plack::App::Proxy->new( remote => "http://london.pm.org/" )->to_app;

builder {
    enable "Cache",
        match_url => '^/.*',               # everything
        cache_dir => '/tmp/plack-cache';
    $app;
};

Save this as app.psgi, run plackup and point our code to http://localhost:5000/ and it's all working!

I asked if we could transfer it over to the Perl NOC team so that it becomes an official community resource (he was already redirecting it to the yapceurope.org domain).

He was more than happy to do so, and has been so helpful in the process.

At the same time I'd like to thank the Perl NOC guys for taking this on. You probably don't realise just how much infrastructure these two guys run on our behalf, and how much more they are taking on!

I'd also like to thank the ACT team who run most of the Perl conferences websites and have setup yapc.eu on their server.

http://yapc.eu/ - points to the http://www.yapceurope.org/ site.

http://yapc.eu/year will redirect you to the relevant historical sites.

• http://yapc.eu/2000


• http://yapc.eu/2001


• http://yapc.eu/2002


• http://yapc.eu/2003


• 2004 - http://belfast.yapc.org/ no longer active


• http://yapc.eu/2005


• http://yapc.eu/2006


• http://yapc.eu/2007


• http://yapc.eu/2008


• http://yapc.eu/2009


• http://yapc.eu/2010


• http://yapc.eu/2011

I hope that for 2012 and future YAPC EU's the site can be hosted directly off this domain and that having this consistency will help everyone remember (and advertise) a single address (improving google and awareness in general).

Thanks for being such a great community to be a part of.

Today I got an email from someone saying “I was told by a person who used Perl for computational genomics applications that it was running out of memory, so he switched to C++. What’s your thoughts on running out of memory in Perl?”

Just for posterity here is my reply (please note I’m no expert on this sort of thing and have never had the problem) was…

Perl has a great garbage collector. But of course if you read in a 1 GB file into memory, then you are using 1 GB, whatever language you use.

So the trick is to read in line by line and process the information that is required. This isn’t always possible, but there could be a few other issues which your college didn’t understand. For example you should not pass large data structures around, you should pass references to them, otherwise they get copied.

my @a_big_list = qw(lots of stuff);
bad(@a_big_list);
good(\@a_big_list);

sub bad {
  my @copy_of_list = @_;
  foreach my $thing (@copy_of_list) { ... }
}

sub good {
  my $list_reference = shift;
  foreach my $thing (@$list_reference) { ... }
}

The other one is if you use global variables all the time, instead of locally scoped variables (which are garbage collected when they go out of scope) you will have lots of extra memory used.

Check out http://www.onyxneon.com/books/modern_perl/ (free) — see “Array References” section for more info.

Programs will run out of memory if the coder doesn’t fully understand what they are doing, no matter what language.

You may also be interested in checking out http://www.bioperl.org/ and asking questions on their IRC channel. Perl is used for mass data processing by these guys so they might have further insights.

http://code.activestate.com/ppm/

As reported http://www.activestate.com/blog/2011/02/ppm-index-new-way-browse-perl-packages.

It is interesting to see which are the popular downloads and as an author the number of downloads of your own modules. They also have a nice chart of which OS's the module has been built for.

Not so sure that the example in the article - DBD::Mysql Failing on OSX - is such a good showcase! (looking at the report just seemed that mysql_config wasn't in the build servers path or something, so a setup issue, not a module issue).

But that aside it's interesting to see how far PPM seems to have come.

http://dev.perl.org/perl5/

Full announcement.

As first it doesn't seem like you have much that wasn't done in Apache (or what ever web server you are using). The moment you realise that you can put everything that was in Apache (rewrite rules, expiry headers, serving static content) into your app.psgi (web application configuration) file and that this will then run under any of the many supported web servers the light bulb goes on.

You can then try Starman or run everything using plackup in your development environment.

The simplicity of Plack's structure $ENV in, [ status, [ headers ], [ content ] ] out makes writing middleware easy and adapting your code to use this standard very clean (even if you don't use one of the many frameworks which already directly support Plack).

I've also added a white paper on Plack to Perl.org.

Thanks to a TPF Grant there is now actual Documentation which really makes using it a whole lot easier! I've had this in production for about 4 years now and it's very stable. Being able to change which servers (or ports) your entire sites traffic goes to make gradual rollouts (and quick rollbacks!) very easy. It also makes upgrading your servers far less complex.

If your not already using a web load balancer infront of your web server check it out!