basho/riak_cs — pull request #1006 by kuenishi (2014-11-04 00:46:43+00:00)
Title: Add sibling explosion test

DVVset is great.

## Benchmark with CS 1.5 & Riak 1.4

.riak_test.config:
```erlang
{sibling_benchmark,
[{write_concurrency, 7}, %% 7 is a magic number where 503 does not occur
{duration_sec, 30},
{version, previous}]
},
```
result: max # of siblings sometimes exceeds 3x more than write concurrency
```
09:40:01.252 [info] siblings Mean: 2 0 0 0
09:40:01.252 [info] siblings Max: 21 0 0 0
09:40:01.252 [info] objsize Mean: 236805 0 0 0
09:40:01.252 [info] objsize Max: 3812184 0 0 0
09:40:01.253 [info] time Mean: 10542 0 0 0
09:40:01.253 [info] time Max: 1119368 0 0 0
09:40:01.306 [info] SiblingCount: 9, HistoryCounts: [373,373,373,373,371,372,371,371,371]
```

## Benchmark with CS develop (2.0 candidate) & Riak 2.0

.riak_test.config:
```erlang
{sibling_benchmark,
[{write_concurrency, 7}, %% 7 is a magic number where 503 does not occur
{duration_sec, 30},
{version, current}]
},
```
result: DVVset is great; # of siblings never exceeds write concurrency
```
09:44:30.237 [info] ====================== benchmark done ====================
09:44:30.238 [info] siblings Mean: 1 0 0 0
09:44:30.238 [info] siblings Max: 7 0 0 0
09:44:30.238 [info] objsize Mean: 109136 0 0 0
09:44:30.238 [info] objsize Max: 841313 0 0 0
09:44:30.238 [info] time Mean: 11034 0 0 0
09:44:30.238 [info] time Max: 719451 0 0 0
09:44:30.246 [info] SiblingCount: 2, HistoryCounts: [248,248]
09:44:30.246 [debug] MaxSib:Concurrency = 7:7
```