After restarted, Listener.Close() doesn't lead Listener.Accept() to return

[wllenyj]

At the StartProcess function, while Listener' s File() is called, this will puts the Listener fd into blocking mode. This should lead to Accept() can't return even if Listener.Close() is called.
Listener File() --> (fd *netFD) dup()

func (fd *netFD) dup() (f *os.File, err error) {
    ns, err := dupCloseOnExec(fd.pfd.Sysfd)
    if err != nil {
        return nil, err 
    }   

    // We want blocking mode for the new fd, hence the double negative.
    // This also puts the old fd into blocking mode, meaning that
    // I/O will block the thread instead of letting us use the epoll server.
    // Everything will still work, just with more threads.
    if err = fd.pfd.SetBlocking(); err != nil {
        return nil, os.NewSyscallError("setnonblock", err)
    }   

    return os.NewFile(uintptr(ns), fd.name()), nil 
}

So, User either use Shutdown to close socket, or use syscall.SetNonblock to put the Listener fd into the nonblock.