rails puma 使用的线程数

Question

我有一个使用 puma 服务器运行的 rails 应用程序。有什么办法，我们可以看到当前应用程序中使用了多少线程？

Answer 1

前段时间我也在想同样的事情，然后遇到了这个issue。作者包括了他们最终用来收集这些统计数据的代码：

module PumaThreadLogger

  def initialize *args
    ret = super *args
    Thread.new do
      while true

        # Every X seconds, write out what the state of this dyno is in a format that Librato understands.
        sleep 5

        thread_count = 0
        backlog = 0
        waiting = 0

        # I don't do the logging or string stuff inside of the mutex. I want to get out of there as fast as possible
        @mutex.synchronize {
          thread_count = @workers.size
          backlog = @todo.size
          waiting = @waiting
        }

        # For some reason, even a single Puma server (not clustered) has two booted ThreadPools.
        # One of them is empty, and the other is actually doing work
        # The check above ignores the empty one
        if (thread_count > 0)

          # It might be cool if we knew the Puma worker index for this worker, but that didn't look easy to me.
          # The good news: By using the PID we can differentiate two different workers on two different dynos with the same name
          # (which might happen if one is shutting down and the other is starting)
          source_name = "#{Process.pid}"

          # If we have a dyno name, prepend it to the source to make it easier to group in the log output
          dyno_name = ENV['DYNO']
          if (dyno_name)
            source_name="#{dyno_name}."+source_name
          end
          msg = "source=#{source_name} "

          msg += "sample#puma.backlog=#{backlog} sample#puma.active_connections=#{thread_count - waiting} sample#puma.total_threads=#{thread_count}"
          Rails.logger.info msg
        end
      end
    end
    ret
  end
end

module Puma
  class ThreadPool
    prepend PumaThreadLogger
  end
end

此代码包含特定于 heroku 的逻辑，但收集 @workers.size 并记录它的核心将在任何环境中工作。