Use only real duration to measure method call performance via Prometheus

db/migrate/20171122211913_add_prometheus_instrumentation_to_application_settings.rb

@@ -13,4 +13,3 @@ class AddPrometheusInstrumentationToApplicationSettings < ActiveRecord::Migratio
     remove_column(:application_settings, :prometheus_metrics_method_instrumentation_enabled)
   end
 end
-

lib/gitlab/metrics/method_call.rb

@@ -6,29 +6,15 @@ module Gitlab
       BASE_LABELS = { module: nil, method: nil }.freeze
       attr_reader :real_time, :cpu_time, :call_count, :labels
 
-      def self.call_real_duration_histogram
-        return @call_real_duration_histogram if @call_real_duration_histogram
-
-        MUTEX.synchronize do
-          @call_real_duration_histogram ||= Gitlab::Metrics.histogram(
-            :gitlab_method_call_real_duration_seconds,
-            'Method calls real duration',
-            Transaction::BASE_LABELS.merge(BASE_LABELS),
-            [0.1, 0.2, 0.5, 1, 2, 5, 10]
-          )
-        end
-      end
-
-      def self.call_cpu_duration_histogram
-        return @call_cpu_duration_histogram if @call_cpu_duration_histogram
+      def self.call_duration_histogram
+        return @call_duration_histogram if @call_duration_histogram
 
         MUTEX.synchronize do
           @call_duration_histogram ||= Gitlab::Metrics.histogram(
-            :gitlab_method_call_cpu_duration_seconds,
-            'Method calls cpu duration',
+            :gitlab_method_call_duration_seconds,
+            'Method calls real duration',
             Transaction::BASE_LABELS.merge(BASE_LABELS),
-            [0.1, 0.2, 0.5, 1, 2, 5, 10]
-          )
+            [0.01, 0.05, 0.1, 0.5, 1])
         end
       end
 
@@ -60,8 +46,7 @@ module Gitlab
         @call_count += 1
 
         if prometheus_enabled? && above_threshold?
-          self.class.call_real_duration_histogram.observe(@transaction.labels.merge(labels), real_time / 1000.0)
-          self.class.call_cpu_duration_histogram.observe(@transaction.labels.merge(labels), cpu_time / 1000.0)
+          self.class.call_duration_histogram.observe(@transaction.labels.merge(labels), real_time / 1000.0)
         end
 
         retval

spec/lib/gitlab/metrics/method_call_spec.rb

@@ -25,11 +25,7 @@ describe Gitlab::Metrics::MethodCall do
         end
 
         it 'observes the performance of the supplied block' do
-          expect(described_class.call_real_duration_histogram)
-            .to receive(:observe)
-                  .with({ module: :Foo, method: '#bar' }, be_a_kind_of(Numeric))
-
-          expect(described_class.call_cpu_duration_histogram)
+          expect(described_class.call_duration_histogram)
             .to receive(:observe)
                   .with({ module: :Foo, method: '#bar' }, be_a_kind_of(Numeric))
 
@@ -44,10 +40,7 @@ describe Gitlab::Metrics::MethodCall do
         end
 
         it 'does not observe the performance' do
-          expect(described_class.call_real_duration_histogram)
-            .not_to receive(:observe)
-
-          expect(described_class.call_cpu_duration_histogram)
+          expect(described_class.call_duration_histogram)
             .not_to receive(:observe)
 
           method_call.measure { 'foo' }
@@ -64,10 +57,7 @@ describe Gitlab::Metrics::MethodCall do
       end
 
       it 'does not observe the performance' do
-        expect(described_class.call_real_duration_histogram)
-          .not_to receive(:observe)
-
-        expect(described_class.call_cpu_duration_histogram)
+        expect(described_class.call_duration_histogram)
           .not_to receive(:observe)
 
         method_call.measure { 'foo' }
@@ -92,7 +82,13 @@ describe Gitlab::Metrics::MethodCall do
   end
 
   describe '#above_threshold?' do
+    before do
+      allow(Gitlab::Metrics).to receive(:method_call_threshold).and_return(100)
+    end
+
     it 'returns false when the total call time is not above the threshold' do
+      expect(method_call).to receive(:real_time).and_return(9)
+
       expect(method_call.above_threshold?).to eq(false)
     end