Improve dashboard loading performance

README.md

@@ -126,6 +126,19 @@ Split.configure do |config|
 end
 ```
 
+The recalculation is triggered while rendering the dashboard, which can make it
+slow when many experiments are due for recalculation at once. On busy
+installations you can turn the on-dashboard calculation off and instead run it
+from a background job (e.g. `Split::ExperimentCatalog.all.each(&:calc_winning_alternatives)`):
+
+```ruby
+Split.configure do |config|
+  config.dashboard_calculate_winning_alternatives = false
+end
+```
+
+The dashboard will then display the most recently calculated probabilities.
+
 ## Extras
 
 ### Weighted alternatives

lib/split/configuration.rb

@@ -29,6 +29,7 @@ class Configuration
     attr_accessor :winning_alternative_recalculation_interval
     attr_accessor :redis
     attr_accessor :dashboard_pagination_default_per_page
+    attr_accessor :dashboard_calculate_winning_alternatives
     attr_accessor :cache
 
     attr_reader :experiments
@@ -234,6 +235,7 @@ def initialize
       @winning_alternative_recalculation_interval = 60 * 60 * 24 # 1 day
       @redis = ENV.fetch(ENV.fetch("REDIS_PROVIDER", "REDIS_URL"), "redis://localhost:6379")
       @dashboard_pagination_default_per_page = 10
+      @dashboard_calculate_winning_alternatives = true
     end
 
     private

lib/split/dashboard.rb

@@ -19,9 +19,9 @@ class Dashboard < Sinatra::Base
     helpers Split::DashboardPaginationHelpers
 
     get "/" do
-      # Display experiments without a winner at the top of the dashboard
-      @experiments = Split::ExperimentCatalog.all_active_first
-      @unintialized_experiments = Split.configuration.experiments.keys - @experiments.map(&:name)
+      @experiment_names = Split::ExperimentCatalog.all_active_first_names
+      @experiments = Split::Experiment.find_many(paginated(@experiment_names))
+      @unintialized_experiments = Split.configuration.experiments.keys - @experiment_names
 
       @metrics = Split::Metric.all
 

lib/split/dashboard/views/_experiment.erb

@@ -4,7 +4,7 @@
   <% experiment_class = "experiment" %>
 <% end %>
 
-<% experiment.calc_winning_alternatives %>
+<% experiment.calc_winning_alternatives if Split.configuration.dashboard_calculate_winning_alternatives %>
 <%
   extra_columns = []
   experiment.alternatives.each do |alternative|

lib/split/dashboard/views/index.erb

@@ -1,4 +1,4 @@
-<% if @experiments.any? %>
+<% if @experiment_names.any? %>
   <p class="intro">The list below contains all the registered experiments along with the number of test participants, completed and conversion rate currently in the system.</p>
 
   <div class="dashboard-controls">
@@ -8,7 +8,7 @@
     <input type="button" id="clear-filter" value="Clear filters" />
   </div>
 
-  <% paginated(@experiments).each do |experiment| %>
+  <% @experiments.each do |experiment| %>
     <% if experiment.goals.empty? %>
       <%= erb :_experiment, :locals => {:goal => nil, :experiment => experiment} %>
     <% else %>
@@ -20,7 +20,7 @@
   <% end %>
 
   <div class="pagination">
-    <%= pagination(@experiments) %>
+    <%= pagination(@experiment_names) %>
   </div>
 <% else %>
   <p class="intro">No experiments have started yet, you need to define them in your code and introduce them to your users.</p>

lib/split/experiment.rb

@@ -24,6 +24,18 @@ def self.find(name)
       end
     end
 
+    def self.find_many(names)
+      names = Array(names)
+      return [] if names.empty?
+
+      data = ExperimentStorage::RedisStorage.load_many(names)
+      names.each_index.filter_map do |i|
+        experiment = new(names[i])
+        experiment.set_alternatives_and_options(data[i])
+        experiment unless experiment.alternatives.empty?
+      end
+    end
+
     def initialize(name, options = {})
       options = DEFAULT_OPTIONS.merge(options)
 

lib/split/experiment_catalog.rb

@@ -4,13 +4,25 @@ module Split
   class ExperimentCatalog
     # Return all experiments
     def self.all
-      # Call compact to prevent nil experiments from being returned -- seems to happen during gem upgrades
-      Split.redis.smembers(:experiments).map { |e| find(e) }.compact
+      Split::Experiment.find_many(experiment_names)
     end
 
     # Return experiments without a winner (considered "active") first
     def self.all_active_first
-      all.partition { |e| not e.winner }.map { |es| es.sort_by(&:name) }.flatten
+      Split::Experiment.find_many(all_active_first_names)
+    end
+
+    def self.all_active_first_names
+      names = experiment_names
+      return names if names.empty?
+
+      winners = Split.redis.hgetall(:experiment_winner)
+      active, finished = names.partition { |name| !winners.key?(name) }
+      active.sort + finished.sort
+    end
+
+    def self.experiment_names
+      Split.redis.smembers(:experiments)
     end
 
     def self.find(name)

lib/split/experiment_storage.rb

@@ -88,13 +88,29 @@ def exists?
         redis.exists?(@name)
       end
 
+      def self.load_many(names)
+        storages = names.map { |name| new(name) }
+        reads = nil
+        Split.redis.pipelined do |pipe|
+          reads = storages.map { |storage| storage.pipeline_read(pipe) }
+        end
+        storages.zip(reads).map { |storage, futures| storage.build_from_raw(*futures.map(&:value)) }
+      end
+
       def load!
-        raw_config, raw_alternatives, raw_metadata, raw_goals = redis.pipelined do |pipe|
-          pipe.hgetall(experiment_config_key)
-          pipe.lrange(@name, 0, -1)
-          pipe.get(metadata_key)
+        self.class.load_many([@name]).first
+      end
+
+      def pipeline_read(pipe)
+        [
+          pipe.hgetall(experiment_config_key),
+          pipe.lrange(@name, 0, -1),
+          pipe.get(metadata_key),
           pipe.lrange(goals_key, 0, -1)
-        end
+        ]
+      end
+
+      def build_from_raw(raw_config, raw_alternatives, raw_metadata, raw_goals)
         config = raw_config.transform_keys(&:to_sym)
 
         {

spec/dashboard_spec.rb

@@ -151,6 +151,21 @@ def link(color)
         expect(last_response.body).to_not include("Reopen Experiment")
       end
     end
+
+    describe "winning alternative calculation" do
+      before { experiment }
+
+      it "recalculates winning alternatives by default" do
+        expect_any_instance_of(Split::Experiment).to receive(:calc_winning_alternatives)
+        get "/"
+      end
+
+      it "skips the calculation when dashboard_calculate_winning_alternatives is false" do
+        Split.configuration.dashboard_calculate_winning_alternatives = false
+        expect_any_instance_of(Split::Experiment).to_not receive(:calc_winning_alternatives)
+        get "/"
+      end
+    end
   end
 
   describe "reopen experiment" do