ruby - 如何阻止主线程退出？

Question

我有这个代码:

5.times do |num|
    puts "Spawning thread ##{num}"
    Thread.new {
        fun
        puts "Thread ##{num} is done"
    }
end

fun 需要很长时间才能完成，因此主线程已经退出。我知道我可以使用 sleep，但如果 fun 花费的时间比预期长怎么办？如何无限期地暂停主线程而不阻塞？

Answer 1

如 documentation for Thread 中所述，你必须join线程:

def fun
  sleep 2
end

threads = []
5.times do |num|
  puts "Spawning thread ##{num}"
  threads << Thread.new {
    fun
    puts "Thread ##{num} is done"
  }
end
threads.each(&:join)

输出:

Spawning thread #0
Spawning thread #1
Spawning thread #2
Spawning thread #3
Spawning thread #4

2 秒后:

Thread #4 is done
Thread #0 is done
Thread #1 is done
Thread #3 is done
Thread #2 is done