redis内存碎片处理_redis 碎片整理

 ads：

关注以下公众号查看更多文章

内存碎片让redis占用比自身实际数据存储更多的内存空间，需要整理redis数据以保证redis内存空间的最大化利用

在redis客户端执行以下命令查看redis内存使用情况

INFO memory

输出如下

# Memory
used_memory:1324112
used_memory_human:1.26M
used_memory_rss:7667712
used_memory_rss_human:7.31M
used_memory_peak:1441312
used_memory_peak_human:1.37M
used_memory_peak_perc:91.87%
used_memory_overhead:1201392
used_memory_startup:1177920
used_memory_dataset:122720
used_memory_dataset_perc:83.94%
allocator_allocated:1306992
allocator_active:7635968
allocator_resident:7635968
total_system_memory:17179869184
total_system_memory_human:16.00G
used_memory_lua:31744
used_memory_vm_eval:31744
used_memory_lua_human:31.00K
used_memory_scripts_eval:0
number_of_cached_scripts:0
number_of_functions:0
number_of_libraries:0
used_memory_vm_functions:32768
used_memory_vm_total:64512
used_memory_vm_total_human:63.00K
used_memory_functions:216
used_memory_scripts:216
used_memory_scripts_human:216B
maxmemory:52428800
maxmemory_human:50.00M
maxmemory_policy:volatile-ttl
allocator_frag_ratio:5.84
allocator_frag_bytes:6328976
allocator_rss_ratio:1.00
allocator_rss_bytes:0
rss_overhead_ratio:1.00
rss_overhead_bytes:31744
mem_fragmentation_ratio:5.87
mem_fragmentation_bytes:6360720
mem_not_counted_for_evict:0
mem_replication_backlog:0
mem_total_replication_buffers:0
mem_clients_slaves:0
mem_clients_normal:21456
mem_cluster_links:0
mem_aof_buffer:0
mem_allocator:libc
active_defrag_running:0
lazyfree_pending_objects:0
lazyfreed_objects:0

used_memory_human:1.26M 数据占用了1.26m

used_memory_rss_human:7.31M 数据实际占用内存 7.31M 

allocator_frag_ratio:5.84 内存碎片化率 5.84

大于1.5，代码需要处理redis内存碎片问题

开启内存碎片整理

config set activedefrag yes

设置内存碎片化超过5m进行碎片整理

config set active-defrag-ignore-bytes 5242880

内存碎片占redis的总内存超过5%时开始碎片整理

config set active-defrag-threshold-lower 5

设置清理过程至少占用cpu 10%

config set active-defrag-cycle-min 10

设置清理过程最大占用cpu 20%

config set active-defrag-cycle-max 20