crifan.com后台又无法登录了。
之前已多次遇到了：
【已解决】crifan.com的WordPress无法登录在wp-login登录页死循环
现在去参考之前过程，搞清楚原因。
先用 SecureCRT的ssh登录后台，看看空间是否满了
[root@crifan ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/vda1 79G 25G 51G 33% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 201M 1.7G 11% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup tmpfs 379M 0 379M 0% /run/user/0
不是空间满的问题。
看来还是cookie的问题。
去看看之前如何解决的。
参考
【已解决】WordPress的PHP的log日志出现：PHP message RedisException OOM command not allowed when used memory maxmemory in plugins redis-cache
去看看
[root@crifan ~]# redis-cli 127.0.0.1:6379> info memory # Memory used_memory:1073741776 used_memory_human:1024.00M used_memory_rss:1140920320 used_memory_rss_human:1.06G used_memory_peak:1081140928 used_memory_peak_human:1.01G used_memory_peak_perc:99.32% used_memory_overhead:247427190 used_memory_startup:791200 used_memory_dataset:826314586 used_memory_dataset_perc:77.01% allocator_allocated:1074155680 allocator_active:1109213184 allocator_resident:1147338752 total_system_memory:3973521408 total_system_memory_human:3.70G used_memory_lua:37888 used_memory_lua_human:37.00K used_memory_scripts:0 used_memory_scripts_human:0B number_of_cached_scripts:0 maxmemory:1073741824 maxmemory_human:1.00G maxmemory_policy:volatile-lru allocator_frag_ratio:1.03 allocator_frag_bytes:35057504 allocator_rss_ratio:1.03 allocator_rss_bytes:38125568 rss_overhead_ratio:0.99 rss_overhead_bytes:-6418432 mem_fragmentation_ratio:1.06 mem_fragmentation_bytes:67219568 mem_not_counted_for_evict:0 mem_replication_backlog:0 mem_clients_slaves:0 mem_clients_normal:49694 mem_aof_buffer:0 mem_allocator:jemalloc-5.1.0 active_defrag_running:0 lazyfree_pending_objects:0
其中：
- used_memory_human:1024.00M
- =1G
- 是我们设置的最大的缓存的大小
- 意思是缓存满了
- 导致cookie无法保存
- 导致登录是循环，无法进入后台
但是，之前已设置了：缓存策略，是把旧的抛弃的
看来没生效？
去看看配置：
/usr/local/redis/etc/redis.conf
cat /usr/local/redis/etc/redis.conf | grep maxmemory
输出：
[root@crifan ~]# cat /usr/local/redis/etc/redis.conf | grep maxmemory # according to the eviction policy selected (see maxmemory-policy). # WARNING: If you have replicas attached to an instance with maxmemory on, # limit for maxmemory so that there is some free RAM on the system for replica # maxmemory <bytes> # maxmemory 473000000 maxmemory 1073741824 # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory # maxmemory-policy noeviction maxmemory-policy volatile-lru # maxmemory-samples 5 # Starting from Redis 5, by default a replica will ignore its maxmemory setting # memory than the one set via maxmemory (there are certain buffers that may # the configured maxmemory setting. # replica-ignore-maxmemory yes # 1) On eviction, because of the maxmemory and maxmemory policy configurations, # e Evicted events (events generated when a key is evicted for maxmemory) # Redis LFU eviction (see maxmemory setting) can be tuned. However it is a good
已经是
maxmemory-policy volatile-lru
感觉没错啊
去搜：
redis maxmemory-policy volatile not work
If your eviction policy is set to any of the volatile-* policies, when running out of memory and having no volatile keys to evict, Redis will return an OOM error.
如果此处volatile-lru生效了，那么此处redis内存被占用完毕，则说明：
此处的缓存都没过期，所以一直都在，没有被排除驱逐 到。。。
“Do you have expiration settings on all your keys? volatile-ttl will only remove keys with an expiration set. This should be in your info output.
If you don’t have expiration ttls set try allkeys-lru or allkeys-random for your policy.”
估计我这里就是：全部的key都没有设置expired，所以没有缓存被清除掉，一直增长直到现在占用了1G内存
那就去试试人家说的：
allkeys-lru
allkeys-random
先去找找含义
“MAXMEMORY POLICY: how Redis will select what to remove when maxmemory is reached. You can select among five behaviors:
- volatile-lru -> remove the key with an expire set using an LRU algorithm
- allkeys-lru -> remove any key according to the LRU algorithm
- volatile-random -> remove a random key with an expire set
- allkeys-random -> remove a random key, any key
- volatile-ttl -> remove the key with the nearest expire time (minor TTL)
- noeviction -> don’t expire at all, just return an error on write operations
Note: with any of the above policies, Redis will return an error on write operations, when there are no suitable keys for eviction.
If you keep the policy at the default ‘noeviction’ or if you choose any of the volatile-* ones without actually having expirable keys in the database, the data will remain in Redis indefinitely.”
说的就是我这种情况
没有设置expirable的key，则就一直放着。。。直到用完内存
allkeys-random：随机的话，有点不合理
allkeys-lru：去找找LRU算法含义
lru算法
Least recently used，最近最少使用
根据数据的历史访问记录来进行淘汰数据，其核心思想是“如果数据最近被访问过，那么将来被访问的几率也更高”。 新数据插入到链表头部； 每当缓存命中（即缓存数据被访问），则将数据移到链表头部； 当链表满的时候，将链表尾部的数据丢弃。
LRU 缓存淘汰算法就是一种常用策略。LRU 的全称是 Least Recently Used，也就是说我们认为最近使用过的数据应该是是「有用的」，很久都没用过的数据应该是无用的，内存满了就优先删那些很久没用过的数据。
那就LRU吧。
usr/local/redis/etc/redis.conf
# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory # is reached. You can select among five behaviors: # # volatile-lru -> Evict using approximated LRU among the keys with an expire set. # allkeys-lru -> Evict any key using approximated LRU. # volatile-lfu -> Evict using approximated LFU among the keys with an expire set. # allkeys-lfu -> Evict any key using approximated LFU. # volatile-random -> Remove a random key among the ones with an expire set. # allkeys-random -> Remove a random key, any key. # volatile-ttl -> Remove the key with the nearest expire time (minor TTL) # noeviction -> Don't evict anything, just return an error on write operations. # # LRU means Least Recently Used # LFU means Least Frequently Used # # Both LRU, LFU and volatile-ttl are implemented using approximated # randomized algorithms.
其实都有解释：
- LRU means Least Recently Used
- LFU means Least Frequently Used
usr/local/redis/etc/redis.conf
# maxmemory-policy noeviction # maxmemory-policy volatile-lru maxmemory-policy allkeys-lru
确保设置好了
[root@crifan etc]# cat /usr/local/redis/etc/redis.conf | grep maxmemory-policy # according to the eviction policy selected (see maxmemory-policy). # maxmemory-policy noeviction # maxmemory-policy volatile-lru maxmemory-policy allkeys-lru
然后重启redis
service redis-server restart
期间，等待了很多秒才返回。
估计内部在清理无效的cookie？
貌似没问题。
再去看看当前是内存占用
[root@crifan etc]# redis-cli 127.0.0.1:6379> info # Server redis_version:5.0.4 redis_git_sha1:00000000 redis_git_dirty:0 redis_build_id:48970c8b51251fe5 redis_mode:standalone os:Linux 3.10.0-957.10.1.el7.x86_64 x86_64 arch_bits:64 multiplexing_api:epoll atomicvar_api:atomic-builtin gcc_version:4.8.5 process_id:18187 run_id:18d0d71fba9c743d46867110d1fa4c6bdd4894c7 tcp_port:6379 uptime_in_seconds:127 uptime_in_days:0 hz:10 configured_hz:10 lru_clock:13162076 executable:/usr/local/redis/bin/redis-server config_file:/usr/local/redis/etc/redis.conf # Clients connected_clients:1 client_recent_max_input_buffer:2 client_recent_max_output_buffer:0 blocked_clients:0 # Memory used_memory:1048363672 used_memory_human:999.80M used_memory_rss:1078218752 used_memory_rss_human:1.00G used_memory_peak:1060377680 used_memory_peak_human:1011.25M used_memory_peak_perc:98.87% used_memory_overhead:247370670 used_memory_startup:791200 used_memory_dataset:800993002 used_memory_dataset_perc:76.46% allocator_allocated:1048583416 allocator_active:1066369024 allocator_resident:1086386176 total_system_memory:3973521408 total_system_memory_human:3.70G used_memory_lua:37888 used_memory_lua_human:37.00K used_memory_scripts:0 used_memory_scripts_human:0B number_of_cached_scripts:0 maxmemory:1073741824 maxmemory_human:1.00G maxmemory_policy:allkeys-lru allocator_frag_ratio:1.02 allocator_frag_bytes:17785608 allocator_rss_ratio:1.02 allocator_rss_bytes:20017152 rss_overhead_ratio:0.99 rss_overhead_bytes:-8167424 mem_fragmentation_ratio:1.03 mem_fragmentation_bytes:29897336 mem_not_counted_for_evict:0 mem_replication_backlog:0 mem_clients_slaves:0 mem_clients_normal:49694 mem_aof_buffer:0 mem_allocator:jemalloc-5.1.0 active_defrag_running:0 lazyfree_pending_objects:0 # Persistence loading:0 rdb_changes_since_last_save:1717 rdb_bgsave_in_progress:0 rdb_last_save_time:1606997562 rdb_last_bgsave_status:ok rdb_last_bgsave_time_sec:18 rdb_current_bgsave_time_sec:-1 rdb_last_cow_size:26120192 aof_enabled:0 aof_rewrite_in_progress:0 aof_rewrite_scheduled:0 aof_last_rewrite_time_sec:-1 aof_current_rewrite_time_sec:-1 aof_last_bgrewrite_status:ok aof_last_write_status:ok aof_last_cow_size:0 # Stats total_connections_received:180 total_commands_processed:12978 instantaneous_ops_per_sec:16 total_net_input_bytes:26399488 total_net_output_bytes:84413520 instantaneous_input_kbps:1.65 instantaneous_output_kbps:138.66 rejected_connections:0 sync_full:0 sync_partial_ok:0 sync_partial_err:0 expired_keys:0 expired_stale_perc:0.00 expired_time_cap_reached_count:0 evicted_keys:0 keyspace_hits:12224 keyspace_misses:468 pubsub_channels:0 pubsub_patterns:0 latest_fork_usec:24467 migrate_cached_sockets:0 slave_expires_tracked_keys:0 active_defrag_hits:0 active_defrag_misses:0 active_defrag_key_hits:0 active_defrag_key_misses:0 # Replication role:master connected_slaves:0 master_replid:57508adf62f3298cd8c8ad657719e2978bacbcd8 master_replid2:0000000000000000000000000000000000000000 master_repl_offset:0 second_repl_offset:-1 repl_backlog_active:0 repl_backlog_size:1048576 repl_backlog_first_byte_offset:0 repl_backlog_histlen:0 # CPU used_cpu_sys:1.918026 used_cpu_user:8.740703 used_cpu_sys_children:1.705528 used_cpu_user_children:14.890031 # Cluster cluster_enabled:0 # Keyspace db0:keys=4485316,expires=174,avg_ttl=86103394
和：
127.0.0.1:6379> config get maxmemory 1) "maxmemory" 2) "1073741824" 127.0.0.1:6379> config get maxmemory-policy 1) "maxmemory-policy" 2) "allkeys-lru" 127.0.0.1:6379> config get maxmemory-samples 1) "maxmemory-samples" 2) "5"
其中：
- used_memory_human:999.80M
- 没有完全占满1G
- 说明是刚才重启redis时，根据最新策略allkeys-lru去清理了一部分cookie了
现在再去登录后台，估计就可以了。
果然可以了。
【总结】
此处登录WordPress后台，又在wp-login死循环了。
后来找到原因了：
之前虽然给redis设置了
/usr/local/redis/etc/redis.conf
maxmemory-policy volatile-lru
但是：
此处WordPress产生的所有的cookie，貌似都是没expire方面的值的-》即 都没有过期的设 置 -》 永远不会过期
导致cookie一直增加，直到占用了所允许的最大内存
注：此处设置是1G
/usr/local/redis/etc/redis.conf
maxmemory 1073741824
解决办法：
把驱逐evict策略改为（不带volatile的）allkeys
- allkeys-lru
- Evict any key using approximated LRU
- LRU=Least Recently Used=最近最少使用
- allkeys-lfu
- Evict any key using approximated LFU
- allkeys-random
- Remove a random key, any key
具体设置办法：
编辑配置文件：
/usr/local/redis/etc/redis.conf
改为：
maxmemory-policy allkeys-lru
即可。
附录：
（1）redis管理命令
- 重启
- service redis-server restart
- 查看状态
- service redis-server status
（2）redis相关命令：
- 进入命令行
- redis-cli
- 查看 全部信息
- info
- 举例
- 查看某方面 section的信息
- 查看内存信息
- info memory
- 查看配置信息：
- config get
- 举例
- 最大内存：maxmemory
- config get maxmemory
- 最大内存（超过时的）驱逐策略：maxmemory-policy
- config get maxmemory-policy
- samples
- config get maxmemory-samples
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