Why do perl dancer pages render slowly (while I'm not connected to internet)? - perl

Question

I'm running Dancer and found it slow -- pages took a long time to render.
This is the example code from Dancer::Introduction:
#!/usr/bin/perl
# make this script a webapp
use Dancer;
# declare routes/actions
get '/' => sub {
"Hello World";
};
get '/hello/:name' => sub {
"Hello ".param('name');
};
# run the webserver
Dancer->dance;
It takes my browser 10 seconds to get&render the response( using firebug in firefox ).
And Dancer message:
[20734] core #0.000228> request: GET / from 192.168.1.101 in /usr/lib/perl5/site_perl/5.8.8/Dancer/Handler.pm l. 57
[20734] core #0.000809> [hit #44]trying to match `/' against /^\/$/ in /usr/lib/perl5/site_perl/5.8.8/Dancer/Route.pm l. 84
[20734] core #0.000953> [hit #44] --> got 1 in /usr/lib/perl5/site_perl/5.8.8/Dancer/Route.pm l. 101
[20734] core #0.001645> [hit #44]response: 200 in /usr/lib/perl5/site_perl/5.8.8/Dancer/Handler.pm l. 175
[20734] core #0.000135> request: GET /favicon.ico from 192.168.1.101 in /usr/lib/perl5/site_perl/5.8.8/Dancer/Handler.pm l. 57
[20734] core #0.000873> [hit #45]response: 200 in /usr/lib/perl5/site_perl/5.8.8/Dancer/Handler.pm l. 175
Why is Dancer so slow? Did I miss something?

Answer 1

Is the computer connected to internet? I got the same problem when testing from a computer not connected to internet; fixed it by deleting
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script>;
from main.tt

Answer 2

As you can see from the debugging log, it took Dancer 0.6ms to serve the request. The problem is somewhere else in the stack. A frequent culprit is reverse DNS — the webserver tries to reverse-lookup the remote IP address for access logging purposes, and if your DNS is misconfigured, that can take quite a while (sometimes 30 or 60 seconds) before it fails.

Answer 3

Use Dancer::Plugin::NYTProf to profile your application. From the documentation:
By simply loading this plugin, you'll have the detailed, helpful
profiling provided by Devel::NYTProf.
Each individual request to your app is profiled. Going to the URL
/nytprof in your app will present a list of profiles.
Or, if it's a browser-side issue, you can use an extension like Firebug to see what part of a page load is slow.