Latency of Riak KV drops with small size server goes long

mtakahashi-ivi mtakahashi at yourinventit.com
Mon Nov 2 16:47:45 EST 2015


I use Riak KV with small size server(c4.xlarge at AWS 1 instance). When I run
riak several days, latency of riak KV seems to be long.
So I checked latency of riak KV by using basho bench with smaller server. At
first, I checked write latency.
My questions are
1. Why write latency drops continuously? How can I avoid it?
2. yokozuna Java process becoms to allocate big siz of memory.
   Initially it is about 500MB, finally it become 2GB. JVM option set in
search.solr.jvm_options is "-Xmx1g", 2GB exceeds the value.
   Is it normal behavior?
3. Write latency also periodically drops every about 10000 sec. What is this
cicle?

------ Result summary -------
<http://riak-users.197444.n3.nabble.com/file/n4033651/summary.png> 

------ Benchmark environment -------
Basho bench server:
 c4.xlarge: 7.5GB RAM

Riak KV Server:
 c4.large: 3.75GB RAM

Riak version: 2.1.1
riak.conf:
 ring_size = 16
 storage_backend = leveldb
 search = on
 Any others except server addresses are same as default value.

Bucket property:
 {
   "props": {
     "name": "BUCKET_A",
     "active": true,
     "allow_mult": false,
     "basic_quorum": false,
     "big_vclock": 50,
     "chash_keyfun": {
       "mod": "riak_core_util",
       "fun": "chash_std_keyfun"
     },
     "claimant": "riak at 172.31.0.160",
     "dvv_enabled": true,
     "dw": "quorum",
     "last_write_wins": false,
     "linkfun": {
       "mod": "riak_kv_wm_link_walker",
       "fun": "mapreduce_linkfun"
     },
     "n_val": 1,
     "notfound_ok": false,
     "old_vclock": 86400,
     "postcommit": [],
     "pr": 0,
     "precommit": [],
     "pw": 0,
     "r": 1,
     "rw": "quorum",
     "search_index": "BUCKET_A_SEARCH_INDEX",
     "small_vclock": 50,
     "w": 1,
     "young_vclock": 20
   }
 }

Basho bench configuration:
 "json_v" is not real one. I modified field names for this report.
-----
{mode, max}.

{duration, 4320}.

{concurrent, 300}.

{driver, basho_bench_driver_http}.

 %% Preload 1 million keys
{key_generator, {int_to_str, {uniform_int, 100000000}}}.
{value_generator, {fixed_bin, 100}}.

{generators, [
    {string_g, {key_generator, {int_to_str, {uniform_int, 50000}}}},
    {bucket_g, {key_generator, {int_to_str, {uniform_int, 3}}}}
]}.

{values, [
    {json_v,
{"{\"attr1_i\":0,\"attr2_i\":0,\"attr3_s\":\"~s\",\"attr4_s\":\"\",\"attr5_i\":4,\"attr6_i\":318,\"attr7_i\":9,\"attr8_i\":4,\"attr9_i\":14,\"attr10_i\":1010,\"attr11_i\":1005,\"attr12_i\":1015,\"attr13_i\":30,\"attr14_i\":15,\"attr15_i\":45,\"attr16_i\":19,\"attr17_i\":14,\"attr18_i\":24,\"attr19_i\":1,\"attr20_l\":1446088404435,\"attr21_i\":1,\"attr22_s\":\"TEST:tstff:000000000000310\",\"attr23_i\":3,\"attr24_s\":\"TESTtstff000000000000310\",\"attr25_l\":1445869988879,\"attr26_l\":1446088413157,\"attr27_i\":6473}",
[string_g]}}
]}.

{headers, [
    {json_h, [{'Content-Type', 'application/json'}]}
]}.

{targets, [
  {map_targets, [
    {"172.31.0.160", 8098, {"/types/BUCKET_TYPE_A/buckets/BUCKET_A/keys/~s",
[key_generator]}}
    ]}
]}.


{operations, [
    {{post, map_targets, json_v, json_h}, 1}
]}.
-----




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