T'is easy.

#!/usr/bin/perl -w

use IO::Socket;
use strict;
use threads;
use threads::shared;

#sock is my connection where I report what is going on
my $sock = IO::Socket::INET->new(
    PeerAddr => 'hostname.org',
    PeerPort => '1234',
    Proto => 'tcp'
);

my $done:shared = 0;
my $thread = async{ long_running_function(); $done = 1 };

print $sock "I'm still here" and sleep 180 until $done;
my $return_value = $thread->join;
print $sock "$return_value\n";
close $sock;
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