Timeline using Redis sorted set

benchmark.rb

require "benchmark"
require "redis"
require "hiredis"
require "redis/connection/hiredis"

redis = Redis.new(timeout: 60)
redis.select(10)

if ARGV.include?("create")
  puts "Creating feeds"
  redis.flushdb
  1000.times do |n|
    50.times do
      r = rand(1..10000)
      redis.zadd "feed:#{n}", r, "Feed #{n}: #{r}"
    end
  end
  exit
end

Benchmark.bm(4) do |bm|
  [10, 100, 200, 400, 600, 800, 1000].each do |n_feed|
    bm.report("#{n_feed}") do
      follows = (0..n_feed).map { |i| "feed:#{i}" }
      redis.zunionstore "timeline", follows
      redis.zrevrange "timeline", 0, 50
    end
  end
end

result.txt

On iMac Core i5 3.4GHz

           user     system      total        real
10     0.000000   0.000000   0.000000 (  0.019222)
100    0.000000   0.000000   0.000000 (  0.263000)
200    0.000000   0.000000   0.000000 (  0.987301)
400    0.000000   0.000000   0.000000 (  4.010479)
600    0.000000   0.000000   0.000000 (  9.127258)
800    0.010000   0.000000   0.010000 ( 16.349298)
1000   0.000000   0.000000   0.000000 ( 25.671639)