最近看到redis4支持內存碎片清理了, 之前一直期待有這麼一個功能, 因爲之前遇到內存碎片的解決辦法就是重啓, 現在終於有了優雅的解決方案.\^o^/, 這個功能其實oranagra 在2017年1月1日已經提交pr了, 相關地址: https://github.com/antirez/redis/pull/3720
版本說明:
- Redis 4.0-RC3 以上版本才支持的
- 需要使用jemalloc作爲內存分配器(默認的)
功能介紹:
- 支持在運行期進行自動內存碎片清理 (config set activedefrag yes)
- 支持通過命令 memory purge 進行清理(與自動清理區域不同)
功能驗證流程:
(1) 首先需要拉取4.0-RC3之後的版本代碼, 編譯
(2) 啓動時限定內存大小爲1g並啓動lru, 命令如下:
./src/redis-server --maxmemory 1gb --maxmemory-policy allkeys-lru --activedefrag no --port 6383
(3) 構造大量數據並導致lru, 這樣可以觸發內存碎片, 命令如下:
redis-cli -p 6383 debug populate 7000000 asdf 150
(4) 查看當前的內存使用情況, 會發現有200多萬的數據被清理掉了
-
$ redis-cli -p 6383 info keyspace
-
# Keyspace
-
db0:keys=4649543,expires=0,avg_ttl=0
(5) 查看當前的內存碎片率, 這時碎片率(mem_fragmentation_ratio)很高 : 1.54, 意味着54%的內存浪費
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$ redis-cli -p 6383 info memory
-
# Memory
-
used_memory:1073741736
-
used_memory_human:1024.00M
-
used_memory_rss:1650737152
-
used_memory_rss_human:1.54G
-
used_memory_peak:1608721680
-
used_memory_peak_human:1.50G
-
used_memory_peak_perc:66.75%
-
used_memory_overhead:253906398
-
used_memory_startup:766152
-
used_memory_dataset:819835338
-
used_memory_dataset_perc:76.41%
-
total_system_memory:67535904768
-
total_system_memory_human:62.90G
-
used_memory_lua:37888
-
used_memory_lua_human:37.00K
-
maxmemory:1073741824
-
maxmemory_human:1.00G
-
maxmemory_policy:allkeys-lru
-
mem_fragmentation_ratio:1.54
-
mem_allocator:jemalloc-4.0.3
-
active_defrag_running:0
-
lazyfree_pending_objects:0
(6) 看看內存分配的詳細情況, 這個地方看不懂可以看看: 科普文, 關鍵的是util指標, 指的是內存利用率, 最大的bins內存util是0.661, 說明內存利用率不高
-
$ echo "`redis-cli -p 6383 memory malloc-stats`"
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___ Begin jemalloc statistics ___
-
Version: 4.0.3-0-ge9192eacf8935e29fc62fddc2701f7942b1cc02c
-
Assertions disabled
-
Run-time option settings:
-
opt.abort: false
-
opt.lg_chunk: 21
-
opt.dss: "secondary"
-
opt.narenas: 48
-
opt.lg_dirty_mult: 3 (arenas.lg_dirty_mult: 3)
-
opt.stats_print: false
-
opt.junk: "false"
-
opt.quarantine: 0
-
opt.redzone: false
-
opt.zero: false
-
opt.tcache: true
-
opt.lg_tcache_max: 15
-
CPUs: 12
-
Arenas: 48
-
Pointer size: 8
-
Quantum size: 8
-
Page size: 4096
-
Min active:dirty page ratio per arena: 8:1
-
Maximum thread-cached size class: 32768
-
Chunk size: 2097152 (2^21)
-
Allocated: 1074509704, active: 1609732096, metadata: 41779072, resident: 1651118080, mapped: 1652555776
-
Current active ceiling: 1610612736
-
arenas[0]:
-
assigned threads: 1
-
dss allocation precedence: secondary
-
min active:dirty page ratio: 8:1
-
dirty pages: 393001:24 active:dirty, 0 sweeps, 0 madvises, 0 purged
-
allocated nmalloc ndalloc nrequests
-
small: 1006565256 28412640 9802493 35714594
-
large: 835584 20 11 20
-
huge: 67108864 1 0 1
-
total: 1074509704 28412661 9802504 35714615
-
active: 1609732096
-
mapped: 1650458624
-
metadata: mapped: 40202240, allocated: 491904
-
bins: size ind allocated nmalloc ndalloc nrequests curregs curruns regs pgs util nfills nflushes newruns reruns
-
8 0 1992 319 70 357 249 1 512 1 0.486 7 8 1 0
-
16 1 148618896 14110300 4821619 14310175 9288681 55119 256 1 0.658 141103 48825 55119 5
-
24 2 112104360 7200400 2529385 7300348 4671015 14064 512 3 0.648 72004 25881 14064 1
-
32 3 288 112 103 7003270 9 1 128 1 0.070 3 7 1 0
-
40 4 360 109 100 171 9 1 512 5 0.017 3 7 1 0
-
48 5 1248 112 86 63 26 1 256 3 0.101 2 5 1 0
-
56 6 896 106 90 16 16 1 512 7 0.031 2 6 1 0
-
64 7 128 64 62 5 2 1 64 1 0.031 1 3 1 0
-
80 8 880 106 95 7 11 1 256 5 0.042 2 4 1 0
-
96 9 9120 212 117 97 95 1 128 3 0.742 4 6 2 1
-
112 10 336 109 106 2 3 1 256 7 0.011 3 6 3 0
-
128 11 640 40 35 4 5 1 32 1 0.156 3 4 2 0
-
160 12 740617440 7000148 2371289 7000001 4628859 54688 128 5 0.661 70271 24334 54689 4
-
192 13 768 68 64 1 4 1 64 3 0.062 2 4 2 0
-
224 14 4683616 100000 79091 99946 20909 781 128 7 0.209 1000 1641 782 0
-
256 15 0 16 16 4 0 0 16 1 1 1 3 1 0
-
320 16 5120 64 48 16 16 1 64 5 0.250 1 3 1 0
-
384 17 768 33 31 2 2 1 32 3 0.062 1 3 1 0
-
448 18 28672 64 0 0 64 1 64 7 1 1 0 1 0
-
512 19 1024 10 8 4 2 1 8 1 0.250 1 2 2 0
-
640 20 0 32 32 1 0 0 32 5 1 1 3 1 0
-
---
-
896 22 48384 85 31 50 54 2 32 7 0.843 2 3 2 0
-
1024 23 3072 10 7 3 3 1 4 1 0.750 1 2 3 0
-
1280 24 20480 16 0 0 16 1 16 5 1 1 0 1 0
-
1536 25 15360 10 0 0 10 2 8 3 0.625 1 0 2 0
-
1792 26 28672 16 0 0 16 1 16 7 1 1 0 1 0
-
2048 27 4096 10 8 2 2 1 2 1 1 1 2 5 0
-
---
-
3584 30 35840 10 0 0 10 2 8 7 0.625 1 0 2 0
-
---
-
5120 32 250880 49 0 49 49 13 4 5 0.942 0 0 13 0
-
---
-
8192 35 81920 10 0 0 10 10 1 2 1 1 0 10 0
-
---
-
large: size ind allocated nmalloc ndalloc nrequests curruns
-
16384 39 16384 2 1 2 1
-
20480 40 40960 2 0 2 2
-
---
-
32768 43 32768 1 0 1 1
-
40960 44 40960 10 9 10 1
-
---
-
81920 48 81920 1 0 1 1
-
---
-
131072 51 131072 1 0 1 1
-
163840 52 163840 1 0 1 1
-
---
-
327680 56 327680 1 0 1 1
-
---
-
1048576 63 0 1 1 1 0
-
---
-
huge: size ind allocated nmalloc ndalloc nrequests curhchunks
-
---
-
67108864 87 67108864 1 0 1 1
-
---
-
--- End jemalloc statistics ---
(7) 開啓自動內存碎片整理
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$ redis-cli -p 6383 config set activedefrag yes
-
OK
(8) 等會兒再看看, 發現內存碎片降低了
-
$ redis-cli -p 6383 info memory
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# Memory
-
used_memory:1073740712
-
used_memory_human:1024.00M
-
used_memory_rss:1253371904
-
used_memory_rss_human:1.17G
-
used_memory_peak:1608721680
-
used_memory_peak_human:1.50G
-
used_memory_peak_perc:66.74%
-
used_memory_overhead:253906398
-
used_memory_startup:766152
-
used_memory_dataset:819834314
-
used_memory_dataset_perc:76.41%
-
total_system_memory:67535904768
-
total_system_memory_human:62.90G
-
used_memory_lua:37888
-
used_memory_lua_human:37.00K
-
maxmemory:1073741824
-
maxmemory_human:1.00G
-
maxmemory_policy:allkeys-lru
-
mem_fragmentation_ratio:1.17
-
mem_allocator:jemalloc-4.0.3
-
active_defrag_running:0
-
lazyfree_pending_objects:0
(9) 可以再看看內存利用率, 可以看到已經上升到0.82
-
$ echo "`redis-cli -p 6383 memory malloc-stats`"
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___ Begin jemalloc statistics ___
-
Version: 4.0.3-0-ge9192eacf8935e29fc62fddc2701f7942b1cc02c
-
Assertions disabled
-
Run-time option settings:
-
opt.abort: false
-
opt.lg_chunk: 21
-
opt.dss: "secondary"
-
opt.narenas: 48
-
opt.lg_dirty_mult: 3 (arenas.lg_dirty_mult: 3)
-
opt.stats_print: false
-
opt.junk: "false"
-
opt.quarantine: 0
-
opt.redzone: false
-
opt.zero: false
-
opt.tcache: true
-
opt.lg_tcache_max: 15
-
CPUs: 12
-
Arenas: 48
-
Pointer size: 8
-
Quantum size: 8
-
Page size: 4096
-
Min active:dirty page ratio per arena: 8:1
-
Maximum thread-cached size class: 32768
-
Chunk size: 2097152 (2^21)
-
Allocated: 1074509800, active: 1307602944, metadata: 41779072, resident: 1512247296, mapped: 1652555776
-
Current active ceiling: 1308622848
-
arenas[0]:
-
assigned threads: 1
-
dss allocation precedence: secondary
-
min active:dirty page ratio: 8:1
-
dirty pages: 319239:39882 active:dirty, 4878 sweeps, 6343 madvises, 33915 purged
-
allocated nmalloc ndalloc nrequests
-
small: 1006565352 35456589 16846439 45126633
-
large: 835584 24 15 24
-
huge: 67108864 1 0 1
-
total: 1074509800 35456614 16846454 45126658
-
active: 1307602944
-
mapped: 1650458624
-
metadata: mapped: 40202240, allocated: 491904
-
bins: size ind allocated nmalloc ndalloc nrequests curregs curruns regs pgs util nfills nflushes newruns reruns
-
8 0 1992 319 70 357 249 1 512 1 0.486 7 8 1 0
-
16 1 148618896 17658482 8369801 17858357 9288681 44332 256 1 0.818 141103 48825 55119 26364
-
24 2 112104360 8897298 4226283 8997246 4671015 11525 512 3 0.791 72004 25881 14064 6205
-
32 3 384 115 103 9371363 12 1 128 1 0.093 4 7 1 0
-
40 4 360 109 100 171 9 1 512 5 0.017 3 7 1 0
-
48 5 1248 112 86 63 26 1 256 3 0.101 2 5 1 0
-
56 6 896 106 90 16 16 1 512 7 0.031 2 6 1 0
-
64 7 128 64 62 5 2 1 64 1 0.031 1 3 1 0
-
80 8 880 106 95 7 11 1 256 5 0.042 2 4 1 0
-
96 9 9120 212 117 97 95 1 128 3 0.742 4 6 2 1
-
112 10 336 109 106 2 3 1 256 7 0.011 3 6 3 0
-
128 11 640 40 35 4 5 1 32 1 0.156 3 4 2 0
-
160 12 740617440 8788058 4159199 8787911 4628859 44056 128 5 0.820 70271 24334 54689 26488
-
192 13 768 68 64 1 4 1 64 3 0.062 2 4 2 0
-
224 14 4683616 110956 90047 110902 20909 467 128 7 0.349 1000 1641 782 105
-
256 15 0 16 16 4 0 0 16 1 1 1 3 1 0
-
320 16 5120 64 48 16 16 1 64 5 0.250 1 3 1 0
-
384 17 768 33 31 2 2 1 32 3 0.062 1 3 1 0
-
448 18 28672 64 0 0 64 1 64 7 1 1 0 1 0
-
512 19 1024 10 8 4 2 1 8 1 0.250 1 2 2 0
-
640 20 0 32 32 1 0 0 32 5 1 1 3 1 0
-
---
-
896 22 48384 85 31 50 54 2 32 7 0.843 2 3 2 0
-
1024 23 3072 10 7 3 3 1 4 1 0.750 1 2 3 0
-
1280 24 20480 16 0 0 16 1 16 5 1 1 0 1 0
-
1536 25 15360 10 0 0 10 2 8 3 0.625 1 0 2 0
-
1792 26 28672 16 0 0 16 1 16 7 1 1 0 1 0
-
2048 27 4096 10 8 2 2 1 2 1 1 1 2 5 0
-
---
-
3584 30 35840 10 0 0 10 2 8 7 0.625 1 0 2 0
-
---
-
5120 32 250880 49 0 49 49 13 4 5 0.942 0 0 13 0
-
---
-
8192 35 81920 10 0 0 10 10 1 2 1 1 0 10 0
-
---
-
large: size ind allocated nmalloc ndalloc nrequests curruns
-
16384 39 16384 2 1 2 1
-
20480 40 40960 2 0 2 2
-
---
-
32768 43 32768 1 0 1 1
-
40960 44 40960 14 13 14 1
-
---
-
81920 48 81920 1 0 1 1
-
---
-
131072 51 131072 1 0 1 1
-
163840 52 163840 1 0 1 1
-
---
-
327680 56 327680 1 0 1 1
-
---
-
1048576 63 0 1 1 1 0
-
---
-
huge: size ind allocated nmalloc ndalloc nrequests curhchunks
-
---
-
67108864 87 67108864 1 0 1 1
-
---
-
--- End jemalloc statistics ---
(10) 別急, 還有一個大招: 手動清理
$ redis-cli -p 6383 memory purge
(11) 再次查看內存使用情況: 發現碎片率降到1.04, 內存利用率到0.998, 內存碎片基本上消滅了^_^
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$ redis-cli -p 6383 info memory
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# Memory
-
used_memory:1073740904
-
used_memory_human:1024.00M
-
used_memory_rss:1118720000
-
used_memory_rss_human:1.04G
-
used_memory_peak:1608721680
-
used_memory_peak_human:1.50G
-
used_memory_peak_perc:66.74%
-
used_memory_overhead:253906398
-
used_memory_startup:766152
-
used_memory_dataset:819834506
-
used_memory_dataset_perc:76.41%
-
total_system_memory:67535904768
-
total_system_memory_human:62.90G
-
used_memory_lua:37888
-
used_memory_lua_human:37.00K
-
maxmemory:1073741824
-
maxmemory_human:1.00G
-
maxmemory_policy:allkeys-lru
-
mem_fragmentation_ratio:1.04
-
mem_allocator:jemalloc-4.0.3
-
active_defrag_running:0
-
lazyfree_pending_objects:0
-
$
配置說明:
-
# Enabled active defragmentation
-
# 碎片整理總開關
-
# activedefrag yes
-
# Minimum amount of fragmentation waste to start active defrag
-
# 內存碎片達到多少的時候開啓整理
-
active-defrag-ignore-bytes 100mb
-
# Minimum percentage of fragmentation to start active defrag
-
# 碎片率達到百分之多少開啓整理
-
active-defrag-threshold-lower 10
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# Maximum percentage of fragmentation at which we use maximum effort
-
# 碎片率小余多少百分比開啓整理
-
active-defrag-threshold-upper 100
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# Minimal effort for defrag in CPU percentage
-
active-defrag-cycle-min 25
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# Maximal effort for defrag in CPU percentage
-
active-defrag-cycle-max 75
總結:
從測試的結果看, 效果還是非常不錯的, 另外在配置中我們可以看到如下一段聲明:
說明現在這個功能還是實驗性質的, 對應的命令在官方文檔中都沒有看到. 但是它也說經過了壓力測試, 而且現在也一年多了, 經受了一些考驗, 可以嘗試小流量上線觀察
TODO redis 內存碎片整理實現