Merge branch '63874-use-process-cpu-time-instead-of-thread-for-cpu-metrics' into 'master'

Use PROCESS_CPUTIME_ID for cpu time metrics

Closes #63874

See merge request gitlab-org/gitlab-ce!30166

lib/gitlab/metrics/system.rb

@@ -57,17 +57,9 @@ module Gitlab
         end
       end
 
-      # THREAD_CPUTIME is not supported on OS X
-      if Process.const_defined?(:CLOCK_THREAD_CPUTIME_ID)
-        def self.cpu_time
-          Process
-            .clock_gettime(Process::CLOCK_THREAD_CPUTIME_ID, :float_second)
-        end
-      else
-        def self.cpu_time
-          Process
-            .clock_gettime(Process::CLOCK_PROCESS_CPUTIME_ID, :float_second)
-        end
+      def self.cpu_time
+        Process
+          .clock_gettime(Process::CLOCK_PROCESS_CPUTIME_ID, :float_second)
       end
 
       # Returns the current real time in a given precision.

spec/lib/gitlab/metrics/system_spec.rb

@@ -52,13 +52,13 @@ describe Gitlab::Metrics::System do
   end
 
   describe '.cpu_time' do
-    it 'returns a Fixnum' do
+    it 'returns a Float' do
       expect(described_class.cpu_time).to be_an(Float)
     end
   end
 
   describe '.real_time' do
-    it 'returns a Fixnum' do
+    it 'returns a Float' do
       expect(described_class.real_time).to be_an(Float)
     end
   end