在过去的一周里，我一直在Ruby中尝试多线程概念。
是的，为了练习，我正在设计一个文件下载器，它可以对URL集合进行并行请求。目前，当中断信号被触发时，我需要安全地关闭线程。我已经阅读了多线程和在运行时捕获信号的理论。然而，尽管有这些理论知识，我仍然不知道如何在实践中使用它们。
无论如何，我将把我的概念验证工作留在下面。
class MultiThread
attr_reader :limit, :threads, :queue
def initialize(limit)
@limit = limit
@threads = []
@queue = Queue.new
end
def add(*args, &block)
queue << [block, args]
end
def invoke
1.upto(limit).each { threads << spawn_thread }
threads.each(&:join)
end
private
def spawn_thread
Thread.new do
Thread.handle_interrupt(RuntimeError => :on_blocking) do
# Nothing to do
end
until queue.empty?
block, args = queue.pop
block&.call(*args)
end
end
end
end
urls = %w[https://example.com]
thread = MultiThread.new(2)
urls.each do |url|
thread.add do
puts "Downloading #{url}..."
sleep 1
end
end
thread.invoke
handle_interrupt的文档令人困惑。试试这个，我基于例如puma使用的connection_pool宝石。
$stdout.sync = true
threads = 3.times.map { |i|
Thread.new {
Thread.handle_interrupt(Exception => :never) do
begin
Thread.handle_interrupt(Exception => :immediate) do
puts "Thread #{i} doing work"
sleep 1000
end
ensure
puts "Thread #{i} cleaning up"
end
end
}
}
Signal.trap("INT") {
puts 'Exiting gracefully'
threads.each { |t|
puts 'killing thread'
t.kill
}
exit
}
threads.each { |t| t.join }
输出：
Thread 1 doing work
Thread 2 doing work
Thread 0 doing work
^CExiting gracefully
killing thread
killing thread
killing thread
Thread 0 cleaning up
Thread 1 cleaning up
Thread 2 cleaning up