Perl server fork vs threads

server-pre-fork.pl

#!/usr/bin/perl

use strict;

use IO::Socket;

sub process_connection {
    my ($sock, $addr) = @_;
    while (my $line = <$sock>) {
        $line =~ s/\015?\012$//;
        if ($line =~ /^$/) {
            print $sock "HTTP/1.0 200 OK\015\012Content-Type: text/plain\015\012\015\012Hello, world!\015\012";
            last;
        };
    };
}

my $server = IO::Socket::INET->new( LocalPort => 5000, Type => SOCK_STREAM, Reuse => 1, Listen => SOMAXCONN ) or die ("bind: $!\n");

warn $server;

sub worker {
    my ($n, $server) = @_;
    while(my $client = $server->accept) {
        #warn "$n: $client";
        my $addr = $client->peerhost;
        process_connection($client, $addr);
    }
}

my @childs;

for my $n (1..20) {
    if (my $pid = fork) {
        push @childs, $pid;
    }
    else {
        worker($n, $server);
        exit 0;
    }
}

foreach my $pid (@childs) {
    waitpid($pid, 0);
}

server-pre-threads.pl

#!/usr/bin/perl

use strict;

use threads;

use IO::Socket;

sub process_connection {
    my ($sock, $addr) = @_;
    while (my $line = <$sock>) {
        $line =~ s/\015?\012$//;
        if ($line =~ /^$/) {
            print $sock "HTTP/1.0 200 OK\015\012Content-Type: text/plain\015\012\015\012Hello, world!\015\012";
            last;
        };
    };
}

my $server = IO::Socket::INET->new( LocalPort => 5000, Type => SOCK_STREAM, Reuse => 1, Listen => SOMAXCONN ) or die ("bind: $!\n");

warn $server;

sub worker {
    my ($n, $server) = @_;
    while(my $client = $server->accept) {
        #warn "$n: $client";
        my $addr = $client->peerhost;
        process_connection($client, $addr);
    }
}

for my $n (1..20) {
    my $thr = threads->create(\&worker, $n, $server);
}

foreach my $thr (threads->list) {
    $thr->join;
}