Added load average to system sampling.

lib/gitlab/metrics/sampler.rb

@@ -43,6 +43,7 @@ def sample
         sample_file_descriptors
         sample_objects
         sample_gc
+        sample_load_average
         flush
       ensure
@@ -98,6 +99,11 @@ def sample_gc
         add_metric('gc_statistics', stats)
       end
+      def sample_load_average
+        loadavg = System.load_average
+        add_metric('sys_loadavg', {:'1min' => loadavg[0], :'5min' => loadavg[1], :'15min' => loadavg[2]})
+      end
+
       def add_metric(series, values, tags = {})
         prefix = sidekiq? ? 'sidekiq_' : 'rails_'

lib/gitlab/metrics/system.rb

@@ -8,7 +8,7 @@ module System
       if File.exist?('/proc')
         # Returns the current process' memory usage in bytes.
         def self.memory_usage
-          mem   = 0
+          mem = 0
           match = File.read('/proc/self/status').match(/VmRSS:\s+(\d+)/)
           if match and match[1]
@@ -21,6 +21,15 @@ def self.memory_usage
         def self.file_descriptor_count
           Dir.glob('/proc/self/fd/*').length
         end
+
+        def self.load_average
+          loadavg = File.read('/proc/loadavg').scan(/\d+.\d+/)
+          if loadavg && loadavg[0] && loadavg[1] && loadavg[2]
+            loadavg[0..2].map { |value| value.to_f }
+          else
+            [0.0, 0.0, 0.0]
+          end
+        end
       else
         def self.memory_usage
           0.0
@@ -29,6 +38,10 @@ def self.memory_usage
         def self.file_descriptor_count
           0
         end
+
+        def self.load_average
+          [0.0, 0.0, 0.0]
+        end
       end
       # THREAD_CPUTIME is not supported on OS X

spec/lib/gitlab/metrics/system_spec.rb

@@ -27,6 +27,14 @@
     end
   end
+  describe '.load_average' do
+    it 'returns the amount of load as 3 values array' do
+      expect(described_class.load_average[0]).to be >= 0.0
+      expect(described_class.load_average[1]).to be >= 0.0
+      expect(described_class.load_average[2]).to be >= 0.0
+    end
+  end
+
   describe '.cpu_time' do
     it 'returns a Fixnum' do
       expect(described_class.cpu_time).to be_an_instance_of(Fixnum)