--- listen(backlog)       ruby 1.7 feature

    listen(2) [manual page] ¹Ԥޤ
    (listenƱ)

    backlog ϡ饤Ȥ³׵αǤǤ
    TCPServer Υ󥹥󥹤Ϻǽ backlog ͤ 5 ޤ

    listen(2) [manual page]  0 ֤ޤ
    Ԥ 㳰 Errno::EXXX ȯޤ

