def fill_pool
      threads = []
      if(@open)
        @lock.synchronize do
          required = min - size
          if(required > 0)
            required.times do
              thread = ActionPool::Thread.new(:pool => self, :respond_thread => @respond_to,
                :a_timeout => @action_timeout, :t_timeout => @thread_timeout, :logger => @logger,
                :autostart => false)
              @threads << thread
              threads << thread
            end
          end
        end
      end
      threads.each{|t|t.start}
      threads
    end
def fill_pool
      threads = []
      if(@open)
        @lock.synchronize do
          required = min - size
          if(required > 0)
            required.times do
              thread = ActionPool::Thread.new(:pool => self, :respond_thread => @respond_to,
                :a_timeout => @action_timeout, :t_timeout => @thread_timeout, :logger => @logger,
                :autostart => false)
              @threads << thread
              threads << thread
            end
          end
        end
      end
      threads.each{|t|t.start}
      threads
    end
Fills the pool with the minimum number of threads
 Returns array of created threads