IO::Select could work too. Get a list of the connections that have data to read from using IO::Select->select, and then read a line from each of them before going back to wait for more input. Only read from the sockets that have something to read, and you won't block.

my $readable = IO::Select->new;
$readable->add($oneSock, $twoSock, $redSock, $blueSock);
while (not $done)
{
  my $ready = IO::Select->select($readable);
  foreach my $socket (@$ready)
  {
    # Deal with whatever $socket has to say
  }
}
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