Question

调用Thread.join会阻止当前（主）线程。但是，当主线程退出时，不会调用join会导致所有生成的线程被杀死。如何在不阻塞主线程的情况下在Ruby中生成持久子线程？

这是加入的典型用法。

for i in 1..100 do
  puts "Creating thread #{i}"
  t = Thread.new(i) do |j|
    sleep 1
    puts "Thread #{j} done"
  end
  t.join
end
puts "#{Thread.list.size} threads"

这给出了

     Creating thread 1  
     Thread 1 done  
     Creating thread 2  
     Thread 2 done  
     ...  
     1 threads

但我正在寻找如何获得这个

    Creating thread 1  
    Creating thread 2  
    ...  
    101 threads  
    Thread 1 done  
    Thread 2 done  
    ...

代码在Ruby 1.8.7和1.9.2中提供相同的输出

Answer 1

你只是将线程累积在另一个容器中，然后在它们全部创建之后逐个join：

my_threads = []
for i in 1..100 do
    puts "Creating thread #{i}"
    my_threads << Thread.new(i) do |j|
        sleep 1
        puts "Thread #{j} done"
    end
end
puts "#{Thread.list.size} threads"

my_threads.each do |t|
    t.join
end

您也无法将线程绑定到i变量，因为i会不断被覆盖，并且您的输出将是100行“Thread 100 done”;相反，你必须将它绑定到i的副本，我已巧妙地将其命名为j。

Answer 2

你需要加入循环之外的线程。

for i in 1..100 do
  puts "Creating thread #{i}"
  t = Thread.new(i) do |mi|
    sleep 1
    puts "Thread #{mi} done"
  end
end

# Wait for all threads to end
Thread.list.each do |t|
  # Wait for the thread to finish if it isn't this thread (i.e. the main thread).
  t.join if t != Thread.current
 end

Thread.join阻塞主线程

2 个答案: