Thanks for testing. I checked, scripts run OK indefinitely long with Windows Server 2008, where real application is supposed to run. The failure occurs at old 32 bit WinXP, where I have a copy for tests and development. So, false alarm, sorry. Perl is Strawberry 5.24 both, + latest modules

Update. Still, something strange is happening. Let now "server" be as simple as:

use strict;
use warnings;
use IO::Socket::INET;

my $PORT = 53123;
my $num  = 0;

my $sock = new IO::Socket::INET(
    LocalHost => '127.0.0.1',
    LocalPort => $PORT,
    Proto     => 'tcp',
    Listen    => 5,
    Reuse     => 1,
) or die;
binmode $sock;

while ( my $client = $sock-> accept ) {
    my $str = do { local $/; <$client> };
    die "$num\n" unless $str eq '123';
    print "$num\n" unless $num ++ % 1000;
}
[download]

And worker:

use strict;
use warnings;
use autodie;
use IO::Socket::INET;

my $PORT = 53123;

while () {
    my $sock = new IO::Socket::INET(
        PeerHost => '127.0.0.1',
        PeerPort => $PORT,
        Proto    => 'tcp',
    ) or die;
    binmode $sock;
    print $sock '123';
    $sock-> close;
    select( undef, undef, undef, 0.01 )
}
[download]

Again, runs OK indefinitely long with Windows Server 2008, 64-bit Perl. And rarely does it go past a few thousands in WinXP, in:

This is perl 5, version 24, subversion 0 (v5.24.0) built for MSWin32-x86-multi-thread-64int

Which is somewhat disturbing. Is this my machine / installation somehow broken? Can't believe it's Perl issue. For not so long ago 32-bit OS (Windows i.e.) and 32-bit Perl were common.