Im stuck on understanding how EV calculcate timers. I have this code: 
#!/usr/bin/perl

use common::sense;
use AnyEvent::HTTP;
use Data::Dumper;


sub do {
    my $iter = shift;
    # It will resolve every timeout problems, but it is not question
    # AnyEvent->now_update;
    my $cv = AnyEvent->condvar; 
    $cv->begin;
    http_get
        'https://imasheep.hurrdurr.org/category/about.html',
        timeout => 2,
        sub {
            my ($body, $hdr) = @_;
            say "$iter $hdr->{Status}";
            unless ($hdr->{Status} == 200) {
                warn Data::Dumper->Dump([$hdr],['hdr']);
            }
            $cv->end;
        }
    ;
    my $timer = AnyEvent->timer(
        after => 300,
        cb    => sub { warn "Exit by timer"; $cv->send },
    );
    my ($n, $t) = (AnyEvent->now,  AnyEvent->time);
    my $d = $t-$n; 
    say "$iter diff = $d, time = $t, now = $n";
    $cv->recv;
}

for (1..4) {
    &do($_);
    sleep(5);
}

[download]
output: 
1 diff = 0.0233771800994873, time = 1427912097.54858, now = 1427912097
+.5252
1 200

2 diff = 5.0014123916626, time = 1427912103.05933, now = 1427912098.05
+791
2 596
$hdr = {
         'Reason' => 'Connection timed out',
         'URL' => 'https://imasheep.hurrdurr.org/category/about.html',
         'Status' => 596
       };

3 diff = 5.00508308410645, time = 1427912108.06631, now = 1427912103.0
+6123
3 200

4 diff = 5.00244045257568, time = 1427912113.56622, now = 1427912108.5
+6378
4 596
$hdr = {
         'Status' => 596,
         'Reason' => 'Connection timed out',
         'URL' => 'https://imasheep.hurrdurr.org/category/about.html'
       };

[download]
Iteration 2 - This is OK for me. Timer was set when internal time has 5 sec lag
Iteration 3 - But I do not understand this case. Everything is the same. Why there is no timeout ???
Iteration 4 - And once again. So every even call to do() generate timeout, and every odd call doesn't generate.
Could you please clarify me about this behaviour?

In reply to AnyEvent timers by EV by bash

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