redis consuming way more memory than keys occupy - redis

Question

Redis is taking way more space in memory than the keys itself:
$ top
> ... 74,2% memory (10gb) 2:17.61 redis-server
But the keys takes no more than 500MB total, I checked using "memory usage" on all keys and summed.
There is something I noticed while running "memory stats":
1) "peak.allocated"
2) (integer) 12556833800
3) "total.allocated"
4) (integer) 12141956128
5) "startup.allocated"
6) (integer) 803216
7) "replication.backlog"
8) (integer) 0
9) "clients.slaves"
10) (integer) 0
11) "clients.normal"
12) (integer) 11537845808
13) "aof.buffer"
14) (integer) 0
15) "lua.caches"
16) (integer) 180552
17) "db.0"
18) 1) "overhead.hashtable.main"
2) (integer) 474232
3) "overhead.hashtable.expires"
4) (integer) 115256
19) "overhead.total"
20) (integer) 11539419064
21) "keys.count"
22) (integer) 8579
23) "keys.bytes-per-key"
24) (integer) 1415217
25) "dataset.bytes"
26) (integer) 602537064
27) "dataset.percentage"
28) "4.9627666473388672"
29) "peak.percentage"
30) "96.695999145507812"
31) "allocator.allocated"
32) (integer) 12143577352
33) "allocator.active"
34) (integer) 12207005696
35) "allocator.resident"
36) (integer) 12250742784
37) "allocator-fragmentation.ratio"
38) "1.005223274230957"
39) "allocator-fragmentation.bytes"
40) (integer) 63428344
41) "allocator-rss.ratio"
42) "1.0035829544067383"
43) "allocator-rss.bytes"
44) (integer) 43737088
45) "rss-overhead.ratio"
46) "0.99665284156799316"
47) "rss-overhead.bytes"
48) (integer) -41005056
49) "fragmentation"
50) "1.0055875778198242"
51) "fragmentation.bytes"
52) (integer) 67843576
There is this clients.normal that is taking all that memory space. Any ideas on how to debug?
This keeps going until it crashes.

Answer 1

1) "peak.allocated"
2) (integer) 12556833800
Because the peak allocated memory is about 10GB. Although you removed many keys, the memory is not return to operation system. Check this for detail.
In order to decrease the memory consumption, you can restart Redis server.