通过ruby脚本进行mongo查询需要很长时间才能执行

Question

我有一个ruby脚本，它连接到远程服务器上的mongo db并执行find_by查询。有时执行时间不到1秒，有时需要大约15分钟才能执行。这可能是造成这种行为的原因吗？

script.rb

select cheffname
from speciality
where speciality in ('Chinese Cuisine', 'Japanese Cuisine')
group by cheffname
having count(*) = 2;

publisher_models.rb

    require '/home/ubuntu/praneetha/check_mongo/publisher_models.rb'
$stdout.sync = true

begin
   count = 1
    user_id = '53ce011f9937d923a4000001'
    while(true)
     puts "count: #{count}"
      t1 = Time.now.utc
      puts "Time.now is ========= #{t1}"
      p = Puser.find_by(:puid => user_id)
      puts "puser is  ====#{p.class}"
      t2 = Time.now.utc
       t3 = t2-t1
      puts "time taken =====> #{t3}"
      if t3>2
        puts "I have an error at time #{t1} and total time is #{t3} "
      end

     count = count + 1
     sleep(300)
     end

end