如何等待Elixir衍生过程像Ruby的Thread#join一样结束

Question

我有以下Ruby代码:

t = Thread.new do
  sleep(1)
  puts "Finished!"
end

t.join

如何在Elixir中编写等效代码？

我写了以下一篇:

spawn fn ->
  :timer.sleep(1000)
  IO.puts "Finished!"
end

:timer.sleep(1000)

它可以工作,但这不等同于Ruby版本.

Answer 1

你可以使用Process.monitor/1和receive为此:

pid = spawn(fn ->
  :timer.sleep(1000)
  IO.puts "Finished!"
end)

# Start monitoring `pid`
ref = Process.monitor(pid)

# Wait until the process monitored by `ref` is down.
receive do
  {:DOWN, ^ref, _, _, _} ->
    IO.puts "Process #{inspect(pid)} is down"
end

输出:

Finished!
Process #PID<0.73.0> is dead

Process #PID<0.73.0> is dead之后印刷Finished!.

Answer 2

而不是瞄准尽可能等同的东西,这就是我认为对于"运行后台进程睡眠一秒,并且在完成之前不退出脚本"的问题的更惯用的方法.

Task.async(fn -> :timer.sleep(1000) end)
|> Task.await