在redis slave上由info命令列出的过期密钥数量与我看到的不一致(Number of expiring keys listed by info command on redis slave not consistent with what I see)

 当我在redis-cli对redis 3.2.4服务器运行info命令时，它会显示我的到期时间： 
 
 expires=223518 
 
 但是，当我运行一个keys *命令并要求每个键的ttl ，并且只打印出ttl> 0的键时，我只看到几百个。 
 
 我认为expires是过期密钥数量的计数，但我甚至不在这个数字的数量级内。 
 
 有人能够确切地澄清expires意味着什么吗？ 这是否包括待过期和先前已过期但尚未驱逐的密钥？ 
 
 
 更新： 
 
 以下是我计算过期密钥数量的方法： 
 
  task count_tmp_keys: :environment do
    redis = Redis.new(timeout: 100)
    keys = redis.keys '*'
    ct_expiring = 0

    keys.each do |k|
      ttl = redis.ttl(k)
      if ttl > 0
        ct_expiring += 1
        puts "Expiring: #{k}; ttl is #{ttl}; total: #{ct_expiring}"
        STDOUT.flush
      end
    end

    puts "Total expiring: #{ct_expiring}"
    puts "Done at #{Time.now}"
  end
 
 当我运行这个脚本时，它显示我总共有78个到期 
 
 当我运行信息时，它说db0:keys=10237963,expires=224098,avg_ttl=0 
 
 因为224098比78大得多，我很困惑。 有没有更好的方法让我获得所有225k到期密钥的列表？ 
 
 另外，我的平均ttl是0怎么样？ 你不期望它是非零的吗？ 
 
 
 UPDATE 
 
 我有新的信息和本地这种情况的简单，100％的责备！ 
 
 重新编写：在笔记本电脑上本地设置两个redis进程。 让一个成为另一个的奴隶。 在从属进程上，设置以下内容： 
 
config set slave-serve-stale-data yes
config set slave-read-only no
 
 现在，连接到从站（而不是主站）并运行： 
 
set foo 1
expire foo 10
 
 10秒后，您将无法再访问foo，但info命令仍会显示您的1个密钥到期，平均ttl为0。 
 
 有人可以解释这种行为吗？ 

When I run the info command in redis-cli against a redis 3.2.4 server, it shows me this for expires:
 
expires=223518
 
However, when I then run a keys * command and ask for the ttl for each key, and only print out keys with a ttl > 0, I only see a couple hundred.
 
I thought that the expires is a count of the number of expiring keys but I am not even within an order of magnitude of this number.
 
Can someone clarify exactly what expires is meant to convey? Does this include both to-be-expired and previously expired but not yet evicted keys?
 
 
Update: 
 
Here is how I counted the number of keys expiring:
 
  task count_tmp_keys: :environment do
    redis = Redis.new(timeout: 100)
    keys = redis.keys '*'
    ct_expiring = 0

    keys.each do |k|
      ttl = redis.ttl(k)
      if ttl > 0
        ct_expiring += 1
        puts "Expiring: #{k}; ttl is #{ttl}; total: #{ct_expiring}"
        STDOUT.flush
      end
    end

    puts "Total expiring: #{ct_expiring}"
    puts "Done at #{Time.now}"
  end
 
When I ran this script it shows I have a total expiring of 78
 
When I run info, it says db0:keys=10237963,expires=224098,avg_ttl=0
 
Because 224098 is so much larger than 78, I am very confused. Is there perhaps a better way for me to obtain a list of all 225k expiring keys?
 
Also, how is it that my average ttl is 0? Wouldn't you expect it to be nonzero?
 
 
UPDATE 
 
I have new information and a simple, 100% repro of this situation locally!
 
To repro: setup two redis processes locally on your laptop. Make one a slave of the other. On the slave process, set the following:
 
config set slave-serve-stale-data yes
config set slave-read-only no
 
Now, connect to the slave (not the master) and run:
 
set foo 1
expire foo 10
 
After 10 seconds, you will no longer be able to access foo, but info command will still show that you have 1 key expiring with an average ttl of 0.
 
Can someone explain this behavior?

原文：https://stackoverflow.com/questions/45844944