前言
原有的內存淘汰機制沒有設置導致redis持久化的時候，內存直接爆掉
步驟
修改配置 | 重啟服務
修改redis.conf的配置文件,並重啟redis服務
############################## MEMORY MANAGEMENT ################################
# Set a memory usage limit to the specified amount of bytes.
# When the memory limit is reached Redis will try to remove keys
# according to the eviction policy selected (see maxmemory-policy).
#
# If Redis can't remove keys according to the policy, or if the policy is
# set to 'noeviction', Redis will start to reply with errors to commands
# that would use more memory, like SET, LPUSH, and so on, and will continue
# to reply to read-only commands like GET.
#
# This option is usually useful when using Redis as an LRU or LFU cache, or to
# set a hard memory limit for an instance (using the 'noeviction' policy).
#
# WARNING: If you have replicas attached to an instance with maxmemory on,
# the size of the output buffers needed to feed the replicas are subtracted
# from the used memory count, so that network problems / resyncs will
# not trigger a loop where keys are evicted, and in turn the output
# buffer of replicas is full with DELs of keys evicted triggering the deletion
# of more keys, and so forth until the database is completely emptied.
#
# In short... if you have replicas attached it is suggested that you set a lower
# limit for maxmemory so that there is some free RAM on the system for replica
# output buffers (but this is not needed if the policy is 'noeviction').
#
maxmemory 32212254720
# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
# is reached. You can select among five behaviors:
#內存不足的情況下,有以下幾種移除key的方式供你選擇
#
# 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.
#1. volatile-lru：從已設置過期時間的數據集（server.db[i].expires）中挑選最近最少使用的數據淘汰
#2. volatile-ttl：從已設置過期時間的數據集（server.db[i].expires）中挑選將要過期的數據淘汰
#3. volatile-random：從已設置過期時間的數據集（server.db[i].expires）中任意選擇數據淘汰
#4. allkeys-lru：當內存不足以容納新寫入數據時，在鍵空間中，移除最近最少使用的key（這個是最常用的）
#5. allkeys-random：從數據集（server.db[i].dict）中任意選擇數據淘汰
#6. no-eviction：禁止驅逐數據，也就是說當內存不足以容納新寫入數據時，新寫入操作會報錯。這個應該沒人使用吧！
#7. volatile-lfu：從已設置過期時間的數據集(server.db[i].expires)中挑選最不經常使用的數據淘汰
#8. allkeys-lfu：當內存不足以容納新寫入數據時，在鍵空間中，移除最不經常使用的key
# LRU means Least Recently Used
# LFU means Least Frequently Used
#
# Both LRU, LFU and volatile-ttl are implemented using approximated
# randomized algorithms.
#
# Note: with any of the above policies, Redis will return an error on write
# operations, when there are no suitable keys for eviction.
#
# At the date of writing these commands are: set setnx setex append
# incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd
# sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby
# zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby
# getset mset msetnx exec sort
#
# The default is:
#volatile-ttl 移除設置過過期時間且最近要過期的key
maxmemory-policy volatile-ttl
# LRU, LFU and minimal TTL algorithms are not precise algorithms but approximated
# algorithms (in order to save memory), so you can tune it for speed or
# accuracy. For default Redis will check five keys and pick the one that was
# used less recently, you can change the sample size using the following
# configuration directive.
#
# The default of 5 produces good enough results. 10 Approximates very closely
# true LRU but costs more CPU. 3 is faster but not very accurate.
#
# maxmemory-samples 5
# Starting from Redis 5, by default a replica will ignore its maxmemory setting
# (unless it is promoted to master after a failover or manually). It means
# that the eviction of keys will be just handled by the master, sending the
# DEL commands to the replica as keys evict in the master side.
#
# This behavior ensures that masters and replicas stay consistent, and is usually
# what you want, however if your replica is writable, or you want the replica to have
# a different memory setting, and you are sure all the writes performed to the
# replica are idempotent, then you may change this default (but be sure to understand
# what you are doing).
#
# Note that since the replica by default does not evict, it may end using more
# memory than the one set via maxmemory (there are certain buffers that may
# be larger on the replica, or data structures may sometimes take more memory and so
# forth). So make sure you monitor your replicas and make sure they have enough
# memory to never hit a real out-of-memory condition before the master hits
# the configured maxmemory setting.
#
# replica-ignore-maxmemory yes
動態修改 | 無需重啟
scrm:0>config set maxmemory 32212254720
"OK"
scrm:0>config get maxmemory
1) "maxmemory"
2) "32212254720"
scrm:0>config set maxmemory-policy volatile-ttl
"OK"
scrm:0>config gscrm-taibao:0>et maxmemory-policy
1) "maxmemory-policy"
2) "volatile-ttl"