如何从Ruby中的线程返回值？

Question

如果我有以下代码:

threads = []
(1..5).each do |i|
  threads << Thread.new { `process x#{i}.bin` } 
end
threads.each do |t|
  t.join
  # i'd like to get the output of the process command now.
end

我需要做什么才能获得进程命令的输出？我怎么能创建一个自定义线程,以便我可以完成这个？

Answer 1

剧本

threads = []
(1..5).each do |i|
  threads << Thread.new { Thread.current[:output] = `echo Hi from thread ##{i}` }
end
threads.each do |t|
  t.join
  puts t[:output]
end

说明如何实现您的需求.它的好处是保持输出与生成它的线程,因此您可以随时加入并获取每个线程的输出.运行时,脚本打印

Hi from thread #1
Hi from thread #2
Hi from thread #3
Hi from thread #4
Hi from thread #5

Answer 2

我发现使用collect将Threads收集到列表中更简单,并使用thread.value连接并返回线程中的值 - 这会将其修剪为:

#!/usr/bin/env ruby
threads = (1..5).collect do |i|
  Thread.new { `echo Hi from thread ##{i}` }
end
threads.each do |t|
  puts t.value
end

运行时,会产生:

Hi from thread #1
Hi from thread #2
Hi from thread #3
Hi from thread #4
Hi from thread #5

Answer 3

这是一种使用#value()和#join()从线程数组中检索值的简单而有趣的方法.

a, b, c = [
  Thread.new { "something" },
  Thread.new { "something else" },
  Thread.new { "what?" }
].map(&:value)

a # => "something"
b # => "something else"
c # => "what?"