Ruby 进程之间的共享变量

问题描述

我有一个 Ruby 程序可以加载两个非常大的 yaml 文件，因此我可以通过分叉一些进程来利用多个内核来提高速度.我试过寻找，但我无法弄清楚如何或什至无法在不同的进程中共享变量.

I have a Ruby program that loads up two very large yaml files, so I can get some speed-up by taking advantage of the multiple cores by forking off some processes. I've tried looking, but I'm having trouble figuring how, or even if, I can share variables in different processes.

以下代码是我目前拥有的:

The following code is what I currently have:

@proteins = ""
@decoyProteins = "" 

fork do
  @proteins = YAML.load_file(database)
  exit
end

fork do
  @decoyProteins = YAML.load_file(database)
  exit
end

p @proteins["LVDK"]

P 因为 fork 显示 nil.

P displays nil though because of the fork.

那么是否有可能让分叉进程共享变量?如果是这样，如何?

So is it possible to have the forked processes share the variables? And if so, how?

推荐答案

一个问题是你需要使用 Process.wait 来等待你的分叉进程完成.另一个是不能通过变量进行进程间通信.看到这个:

One problem is you need to use Process.wait to wait for your forked processes to complete. The other is that you can't do interprocess communication through variables. To see this:

@one = nil
@two = nil
@hash = {}
pidA = fork do
    sleep 1
    @one = 1
    @hash[:one] = 1
    p [:one, @one, :hash, @hash] #=> [ :one, 1, :hash, { :one => 1 } ]
end
pidB = fork do
    sleep 2
    @two = 2
    @hash[:two] = 2
    p [:two, @two, :hash, @hash] #=> [ :two, 2, :hash, { :two => 2 } ]
end
Process.wait(pidB)
Process.wait(pidA)
p [:one, @one, :two, @two, :hash, @hash] #=> [ :one, nil, :two, nil, :hash, {} ]

进程间通信的一种方式是使用管道(IO::pipe).在叉之前打开它，然后让叉的每一侧关闭管道的一端.

One way to do interprocess communication is using a pipe (IO::pipe). Open it before you fork, then have each side of the fork close one end of the pipe.

来自 ri IO::pipe:

    rd, wr = IO.pipe

    if fork
      wr.close
      puts "Parent got: <#{rd.read}>"
      rd.close
      Process.wait
    else
      rd.close
      puts "Sending message to parent"
      wr.write "Hi Dad"
      wr.close
    end

 _produces:_

    Sending message to parent
    Parent got: <Hi Dad>

如果要共享变量，请使用线程:

If you want to share variables, use threads:

@one = nil
@two = nil
@hash = {}
threadA = Thread.fork do
    sleep 1
    @one = 1
    @hash[:one] = 1
    p [:one, @one, :hash, @hash] #=> [ :one, 1, :hash, { :one => 1 } ] # (usually)
end
threadB = Thread.fork do
    sleep 2
    @two = 2
    @hash[:two] = 2
    p [:two, @two, :hash, @hash] #=> [ :two, 2, :hash, { :one => 1, :two => 2 } ] # (usually)
end
threadA.join
threadB.join
p [:one, @one, :two, @two, :hash, @hash] #=> [ :one, 1, :two, 2, :hash, { :one => 1, :two => 2 } ]

但是，我不确定当您受到 IO 限制时线程处理是否会给您带来任何好处.

However, I'm not sure if threading will get you any gain when you're IO bound.