大家好，首次发帖呀。最近在苦修 Ruby，刚好需要记录好几台机器的内存信息，就写了个 socket 程序，基本功能是实现了，但是还是有点问题想破脑壳……智商不够用啊……程序是这样的： 首先开始服务端 server，然后开启客户端 client，建立连接之后 server 发送 start，每台机器的 client 开始发送信息到 server。最后记录完毕，server 发送 stop 关闭 socket。

server：

require 'socket'

# This method expects a socket connected to a client.
# It reads the logs from the client and control the client(start or stop).
# Multiple threads may run this method at the same time.

def handle_client(c, cmd)
    command = cmd
    # Connection feekback
    c.puts "Log service running on #{Socket.gethostname}"
    c.flush 
    puts "Accepted connection from #{c.peeraddr[2]}"
    c.puts command

    while true
        remsg = c.gets.chop
        puts "#{c.peeraddr[2]}: #{remsg}"   # Main work
        c.puts command                      # Control the client
        c.flush
        break if command == "stop"
    end 
    c.close
end

server = TCPServer.open(2000)
cmd = ""
# Wait for the command 
cmdThread = Thread.new do
    loop do
        cmd = STDIN.gets.chop
        if cmd == "stop"
            break
        elsif cmd == "start"
            STDOUT.puts "Log service start!"
        else
            STDOUT.puts "Unreasonable command!"
        end
    end
end

while true  
    if cmd == "start" || cmd == "stop"
        client = server.accept
        puts "Client connected. CMD: #{cmd}."
        Thread.start(client) do |c|
            handle_client(c, cmd)
        end
    end
end

client：

require 'socket'

host, port = ARGV
interval = 1

begin
    # Give the user some feedback while connecting.
    STDOUT.print "Connecting..."
    STDOUT.flush
    s = TCPSocket.open(host, port)
    STDOUT.puts "done"

    # Now display information about the connection
    local, peer = s.addr, s.peeraddr
    STDOUT.print "Connected to #{peer[2]}:#{peer[1]}"
    STDOUT.puts " using local port #{local[1]}"

    msg = s.gets
    STDOUT.puts msg.chop            # And display it


    # Waiting the "start" command from server.
    loop do
        STDOUT.puts "Waiting the commands from server."
        msg = s.gets.chop
        STDOUT.puts "Server Command: #{msg}." 
        if msg == "start"
            break
        else
            STDOUT.puts "Unreasonable commands!"
        end
    end

    # Now begin a loop of client/server interaction.
    loop do
        STDOUT.print '> '
        STDOUT.flush

        meminfo = `free`.split "\n"

        memused = meminfo[2].split[2].to_f
        memtotal = meminfo[1].split[1].to_f
        memcost = (memused / memtotal).round(4)

        STDOUT.puts "#{Time.new} MemCost: #{memcost}"
        s.puts(memcost)            # Send the logs to the server
        s.flush

        # Read the server's response and print out.
        # The server may send more than one line, so use readpartial
        # to read whatever it sends (as long as it all arrives in one chunk).
        response = s.readpartial(4096)
        break if response.chop == "stop"
        sleep(interval)
    end

rescue              # If anything goes wrong
    puts $!         # Display the exception to the user
ensure
    s.close if s
end

现在的问题是，server 发送 start 没问题，可是发送不了 stop……求大牛拯救！