Add benchmark for many collectors

judoscale-sidekiq/lib/judoscale/sidekiq/metrics_collector.rb

@@ -6,11 +6,17 @@
 module Judoscale
   module Sidekiq
     class MetricsCollector < Judoscale::JobMetricsCollector
+      RECENT = 1 # second
+      RECENT_KEY = "judoscale:sidekiq:recent"
+      RECENT_VALUE = "1"
+
       def self.adapter_config
         Judoscale::Config.instance.sidekiq
       end
 
       def collect
+        return [] if collected_recently?
+
         metrics = []
         queues_by_name = ::Sidekiq::Queue.all.each_with_object({}) do |queue, obj|
           obj[queue.name] = queue
@@ -45,6 +51,13 @@ def collect
         log_collection(metrics)
         metrics
       end
+
+      private
+
+      def collected_recently?
+        # If another process has collected metrics recently, we don't need to.
+        !::Sidekiq.redis { |r| r.set RECENT_KEY, RECENT_VALUE, nx: true, ex: RECENT }
+      end
     end
   end
 end

judoscale-sidekiq/test/benchmarks/collect_benchmark.rb → judoscale-sidekiq/test/benchmarks/collect_with_large_queues_benchmark.rb

@@ -4,7 +4,7 @@
 require "minitest/benchmark"
 require "judoscale/sidekiq/metrics_collector"
 
-class CollectBenchmark < Minitest::Benchmark
+class CollectWithLargeQueuesBenchmark < Minitest::Benchmark
   BATCH_SIZE = 1_000
   MAX_RETRIES = 3
 

judoscale-sidekiq/test/benchmarks/collect_with_many_reporters_benchmark.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "minitest/benchmark"
+require "judoscale/sidekiq/metrics_collector"
+
+class CollectWithManyReportersBenchmark < Minitest::Benchmark
+  BATCH_SIZE = 1_000
+  QUEUES = %w[one two three four five six seven eight nine ten]
+
+  # performance assertions will iterate over `bench_range`.
+  # We'll use it to define the number Collector instances running.
+  def self.bench_range
+    [1, 100]
+  end
+
+  def setup
+    @collectors = {}
+    sidekiq_args = BATCH_SIZE.times.map { [] }
+
+    # Enqueue jobs on several queues
+    QUEUES.each do |queue|
+      Sidekiq::Client.push_bulk "class" => "Foo", "args" => sidekiq_args, "queue" => queue
+    end
+
+    self.class.bench_range.each do |n|
+      @collectors[n] = n.times.map { Judoscale::Sidekiq::MetricsCollector.new }
+    end
+
+    # Run a collection to prime the cache (what cache?)
+    Judoscale::Sidekiq::MetricsCollector.new.collect
+  end
+
+  def bench_collect
+    validation = proc do |range, times|
+      # 100 collectors should take way less than 100x the time of 1 collector.
+      # The 50x factor is arbitrary, but it's a good indicator that we're short-circuiting
+      # the collection process for redundant collectors.
+      assert_operator times.last, :<, times.first * 50
+    end
+
+    assert_performance validation do |n|
+      @collectors.fetch(n).each do |collector|
+        collector.collect
+      end
+    end
+  end
+end