需求：redis作为一个内存型的数据库，我们需要对过期key保持关注，从info keyspace中可以看出有多少key没有设置过期时间，那么到底是哪些呢？
说明：关于redis ttl 的返回值，请参考http://redisdoc.com/key/ttl.html

测试数据：

  1. 5.5.5.101:6379> get c_100
  2. "100"
  3. 5.5.5.101:6379> ttl c_100
  4. (integer) -1
  5. 5.5.5.101:6379> expire c_100 600
  6. (integer) 1
  7. 5.5.5.101:6379> expire c_1000 600
  8. (integer) 1
  9. 5.5.5.101:6379> expire c_888 600
  10. (integer) 1
  11. 5.5.5.101:6379> dbsize
  12. (integer) 10000
  13. 5.5.5.101:6379> info keyspace
  14. # Keyspace
  15. db0:keys=10000,expires=3,avg_ttl=583699

获取没有设置ttl过期的key名字

  1. db_ip=5.5.5.101
  2. db_port=6379
  3. password=abc123
  4. cursor=0
  5. cnt=100
  6. new_cursor=0
  7. redis-cli -h $db_ip -p $db_port -a $password scan $cursor count $cnt > scan_tmp_result
  8. new_cursor=`sed -n '1p' scan_tmp_result`
  9. sed -n '2,$p' scan_tmp_result > scan_result
  10. cat scan_result |while read line
  11. do
  12.     ttl_result=`redis-cli -h $db_ip -p $db_port -a $password ttl $line`
  13.     if [[ $ttl_result == -1 ]];then
  14.         echo $line >> no_ttl.log
  15.     fi
  16. done
  17. while [ $cursor -ne $new_cursor ]
  18. do
  19.     redis-cli -h $db_ip -p $db_port -a $password scan $new_cursor count $cnt > scan_tmp_result
  20.     new_cursor=`sed -n '1p' scan_tmp_result`
  21.     sed -n '2,$p' scan_tmp_result > scan_result
  22.     cat scan_result |while read line
  23.     do
  24.         ttl_result=`redis-cli -h $db_ip -p $db_port -a $password ttl $line`
  25.         if [[ $ttl_result == -1 ]];then
  26.             echo $line >> no_ttl.log
  27.         fi
  28.     done
  29. done
  30. rm -rf scan_tmp_result
  31. rm -rf scan_result

查看结果：

  1. [redis@lxd-vm1 ~]$ wc -l no_ttl.log
  2. 9997 no_ttl.log
  3. [redis@lxd-vm1 ~]$

线上redis有一些历史遗留的未设置过期时间的key，导致redis空间占用较多，DBA告警后要我们自己清除，于是我写了一个脚本在不影响线上服务的情况下清除（使用keys命令会导致请求hang住）

  1. import sys
  2. import redis
  3. import os
  4. pool = redis.ConnectionPool(host = "host_name",password = "pass_word",port = 6379)
  5. r = redis.StrictRedis(connection_pool = pool)
  6. match = sys.argv[1]+"*"
  7. print(match)
  8. count = 10000
  9. for key in r.scan_iter(match = match,count = count):
  10.     time = r.ttl(key)
  11.     if time==-1:
  12.         r.expire(key,1000)
  13.         print("set expire key:",key)
  14.     print(time)

这里host_name和pass_word打个码
sys.argv[1]指传入的第一个参数，执行的时候就用python3 xxx.py hello 就会自动扫描hello开头的key，步进10000个，然后将其过期时间设为1000秒，过一会就自动过期了。
在业务低峰期的话步进可以设大点，这样清的会比较快，我们为了清几十万个key花了半个多小时。

  1. ServiceStack.Redis\tests\ServiceStack.Redis.Tests\RedisClientTestsBase.cs
  2. using NUnit.Framework;
  3. using System.Diagnostics;
  4. using System.Text;
  6. namespace ServiceStack.Redis.Tests
  7. {
  8.     public class RedisClientTestsBase
  9.     {
  10.         protected string CleanMask = null;
  11.         protected RedisClient Redis;
  13.         protected void Log(string fmt, params object[] args)
  14.         {
  15.             Debug.WriteLine("{0}", string.Format(fmt, args).Trim());
  16.         }
  18.         [OneTimeSetUp]
  19.         public virtual void OnBeforeTestFixture()
  20.         {
  21.             RedisClient.NewFactoryFn = () => new RedisClient(TestConfig.SingleHost);
  22.             using (var redis = RedisClient.New())
  23.             {
  24.                 redis.FlushAll();
  25.             }
  26.         }
  28.         [OneTimeTearDown]
  29.         public virtual void OnAfterTestFixture()
  30.         {
  31.         }
  33.         [SetUp]
  34.         public virtual void OnBeforeEachTest()
  35.         {
  36.             Redis = RedisClient.New();
  37.         }
  39.         [TearDown]
  40.         public virtual void OnAfterEachTest()
  41.         {
  42.             try
  43.             {
  44.                 if (Redis.NamespacePrefix != null && CleanMask == null) CleanMask = Redis.NamespacePrefix + "*";
  45.                 if (CleanMask != null) Redis.SearchKeys(CleanMask).ForEach(t => Redis.Del(t));
  46.                 Redis.Dispose();
  47.             }
  48.             catch (RedisResponseException e)
  49.             {
  50.                 // if exception has that message then it still proves that BgSave works as expected.
  51.                 if (e.Message.StartsWith("Can't BGSAVE while AOF log rewriting is in progress"))
  52.                     return;
  54.                 throw;
  55.             }
  56.         }
  58.         protected string PrefixedKey(string key)
  59.         {
  60.             return string.Concat(Redis.NamespacePrefix, key);
  61.         }
  63.         public RedisClient GetRedisClient()
  64.         {
  65.             var client = new RedisClient(TestConfig.SingleHost);
  66.             return client;
  67.         }
  69.         public RedisClient CreateRedisClient()
  70.         {
  71.             var client = new RedisClient(TestConfig.SingleHost);
  72.             return client;
  73.         }
  75.         public string GetString(byte[] stringBytes)
  76.         {
  77.             return Encoding.UTF8.GetString(stringBytes);
  78.         }
  80.         public byte[] GetBytes(string stringValue)
  81.         {
  82.             return Encoding.UTF8.GetBytes(stringValue);
  83.         }
  84.     }
  85. }
  86. ServiceStack.Redis\tests\ServiceStack.Redis.Tests\RedisScanTests.cs
  87. [Test]
  88. public void Can_scan_100_collection_over_cursor()
  89. {
  90.     var allKeys = new HashSet<string>();
  91.     Redis.FlushAll();
  92.     var keys = 100.Times(x => "KEY" + x);
  93.     Redis.SetAll(keys.ToSafeDictionary(x => x));
  95.     var i = 0;
  96.     var ret = new ScanResult();
  97.     while (true)
  98.     {
  99.         ret = Redis.Scan(ret.Cursor, 10);
  100.         i++;
  101.         ret.AsStrings().ForEach(x => allKeys.Add(x));
  102.         if (ret.Cursor == 0) break;
  103.     }
  105.     Assert.That(i, Is.GreaterThanOrEqualTo(2));
  106.     Assert.That(allKeys.Count, Is.EqualTo(keys.Count));
  107.     Assert.That(allKeys, Is.EquivalentTo(keys));
  108. }

https://www.cnblogs.com/imdba/p/10161343.html