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.

"Can't believe it's Perl issue."

Clearly it is a Windows limitation. Would you mind sharing the requirements as to why you need asynchronous IO? Most of us do very well by leveraging existing tools such as database and web servers. xD