#!/usr/bin/env perl 
use strict;
use warnings;

use AnyEvent;

my $cv     = AnyEvent->condvar;
my @timers = (
    AnyEvent->timer (
        after    => 2,
        interval => 5,
        cb       => sub {
            warn "Timer 1 at " . AnyEvent->now . "\n";
        }
    ),      
    AnyEvent->timer (
        after    => 2,
        interval => 7,
        cb       => sub {
            warn "Timer 2 at " . AnyEvent->now . "\n";
        }
    ),  
    AnyEvent->timer (
        after => 20,
        cb    => sub {
            warn "Timer 3 at " . AnyEvent->now . "\n";
            $cv->send;
        }
    ),  
);          
$cv->recv;  

##</code><code>##

Timer 1 at 1591953440.37264
Timer 2 at 1591953440.37264
Timer 1 at 1591953445.37213
Timer 2 at 1591953447.37533
Timer 1 at 1591953450.36854
Timer 2 at 1591953454.38475
Timer 1 at 1591953455.36656
Timer 3 at 1591953458.37977

##</code><code>##

#!/usr/bin/env perl 
use strict;
use warnings;

use AnyEvent;
use AnyEvent::Ping;
use Data::Dumper;

my @todoList = map { "192.168.100." . $_ } (1 .. 5);
        
my $cv     = AnyEvent->condvar;
my @timers = (   
    AnyEvent->timer (
        after    => 2,
        interval => 5,
        cb       => sub {
            warn "Timer 1 at " . AnyEvent->now . "\n";
            ping_hosts (1, @todoList);
        }
    ),      
    AnyEvent->timer (
        after    => 2,
        interval => 7,
        cb       => sub {
            warn "Timer 2 at " . AnyEvent->now . "\n";
            ping_hosts (2, @todoList);
        }   
    ),  
    AnyEvent->timer (
        after => 20,
        cb    => sub {
            warn "Timer 3 at " . AnyEvent->now . "\n";
            $cv->send;
        }
    ),
);
$cv->recv;

sub ping_hosts {
    my ($num, @hosts) = @_;

    my $ping_timeout  = 2;     #seconds to wait for response
    my $ping_attempts = 4;     #number of pings to issue,
    my $ping_pktsize  = 32;    #packet size of ping
    my $ping = AnyEvent::Ping->new (packet_size => $ping_pktsize);
    $ping->timeout ($ping_timeout);

    #$cv_ping->begin(sub { shift->send($_[0]) });
    foreach my $host (@hosts) {
        $ping->ping (
            $host,
            $ping_attempts,
            sub {
                print "Pinger $num: $host state:" . Dumper ($_[0]) . "\n";
            }
        );
    }
}