test-server.pl:

##!/usr/bin/perl

use HTTP::Daemon;
use Data::Dumper;

my $d = HTTP::Daemon->new(
    LocalAddr => 'localhost',
    LocalPort => 4242,
    ReuseAddr => 1
) || die;

my $cnt;
# response loop
while (my $c = $d->accept) {
    while (my $request = $c->get_request) {
        print "Request:\n".Dumper($request);

        my $response = HTTP::Response->new( 200, 'OK');
        $response->header('Content-Type' => 'text/html'),
        $response->content("$cnt Working!");
        $cnt++;

        # print "Response:\n".Dumper($response);
        $c->send_response($response);
    }
    $c->close;
    undef($c);
}
[download]

test-client.pl:

#perl

use LWP::UserAgent;
use HTTP::Request;

my $ua = LWP::UserAgent->new;

for(1..10000){
    ## build request
    print "$_ GET:\n";
    $req = HTTP::Request->new('GET' => 'http://localhost:4242/');

    ## Pass request to the user agent and get a response back
    my $res = $ua->request($req);
    if ($res->is_success) {
          print $res->status_line ."\n". $res->headers->as_string . $r
+es->content;
    }else{
          print $res->status_line, "\n";
    }
    print "\n\n";

    sleep(1);
}
[download]

Start the server and then use your browser to connect to http://localhost:4242. Hit reload a couple of times. It will work. Then fire the test-client.pl script and it will hang on request number one.

Stop the server. Then try it the other way round: First start the server again. Then fire the test-client.pl and this time it will count up requests. Now, as soon as you use your browser to connect to http://localhost:4242 the test-client will stop getting requests through, while the browser does, doing reloads again and again, as if it could grab the socket from the test-client. (Even better: as soon as you close the browser(!), not just the tab, the CLI test-client resumes counting up successful requests.)

Although this is a non-forking server, it should process one request after another. Right? But it seems as if it serves only one connection/one client on a first come first serve basis. Blocking all other requests...

I've never got my head completely around Socket programming, and in the past I ran into the strangest blocking issues. This here somehow seems related.
I've seen the same behavior with Net::Server, POE and Anyevent based server scripts, so it seems to be related to what I am doing with these modules... What am I missing??