Remove remaining traces of the Allocations Gem

In MR https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/15834 we
removed use of the data produced by the Allocations Gem. However, we
never removed the code that just enables tracking of allocations. In
this commit we remove all remaining traces of this Gem.

Gemfile

@@ -299,7 +299,6 @@ gem 'peek-sidekiq', '~> 1.0.3'
 
 # Metrics
 group :metrics do
-  gem 'allocations', '~> 1.0', require: false, platform: :mri
   gem 'method_source', '~> 0.8', require: false
   gem 'influxdb', '~> 0.2', require: false
 

Gemfile.lock

@@ -49,7 +49,6 @@ GEM
       public_suffix (>= 2.0.2, < 4.0)
     aes_key_wrap (1.0.1)
     akismet (2.0.0)
-    allocations (1.0.5)
     arel (6.0.4)
     asana (0.6.0)
       faraday (~> 0.9)
@@ -974,7 +973,6 @@ DEPENDENCIES
   acts-as-taggable-on (~> 5.0)
   addressable (~> 2.5.2)
   akismet (~> 2.0)
-  allocations (~> 1.0)
   asana (~> 0.6.0)
   asciidoctor (~> 1.5.6)
   asciidoctor-plantuml (= 0.0.8)

Gemfile.rails5.lock

@@ -52,7 +52,6 @@ GEM
       public_suffix (>= 2.0.2, < 4.0)
     aes_key_wrap (1.0.1)
     akismet (2.0.0)
-    allocations (1.0.5)
     arel (7.1.4)
     asana (0.6.0)
       faraday (~> 0.9)
@@ -984,7 +983,6 @@ DEPENDENCIES
   acts-as-taggable-on (~> 5.0)
   addressable (~> 2.5.2)
   akismet (~> 2.0)
-  allocations (~> 1.0)
   asana (~> 0.6.0)
   asciidoctor (~> 1.5.6)
   asciidoctor-plantuml (= 0.0.8)

changelogs/unreleased/remove-allocations-gem.yml

+---
+title: Remove remaining traces of the Allocations Gem
+merge_request:
+author:
+type: changed

lib/gitlab/metrics/samplers/influx_sampler.rb

@@ -16,12 +16,6 @@ module Gitlab
 
           @last_minor_gc = Delta.new(GC.stat[:minor_gc_count])
           @last_major_gc = Delta.new(GC.stat[:major_gc_count])
-
-          if Gitlab::Metrics.mri?
-            require 'allocations'
-
-            Allocations.start
-          end
         end
 
         def sample

lib/gitlab/metrics/samplers/ruby_sampler.rb

@@ -20,16 +20,6 @@ module Gitlab
           {}
         end
 
-        def initialize(interval)
-          super(interval)
-
-          if Metrics.mri?
-            require 'allocations'
-
-            Allocations.start
-          end
-        end
-
         def init_metrics
           metrics = {}
           metrics[:sampler_duration] = Metrics.histogram(with_prefix(:sampler_duration, :seconds), 'Sampler time', { worker: nil })

spec/lib/gitlab/metrics/samplers/influx_sampler_spec.rb

@@ -3,10 +3,6 @@ require 'spec_helper'
 describe Gitlab::Metrics::Samplers::InfluxSampler do
   let(:sampler) { described_class.new(5) }
 
-  after do
-    Allocations.stop if Gitlab::Metrics.mri?
-  end
-
   describe '#start' do
     it 'runs once and gathers a sample at a given interval' do
       expect(sampler).to receive(:sleep).with(a_kind_of(Numeric)).twice

spec/lib/gitlab/metrics/samplers/ruby_sampler_spec.rb

@@ -8,10 +8,6 @@ describe Gitlab::Metrics::Samplers::RubySampler do
     allow(Gitlab::Metrics::NullMetric).to receive(:instance).and_return(null_metric)
   end
 
-  after do
-    Allocations.stop if Gitlab::Metrics.mri?
-  end
-
   describe '#sample' do
     it 'samples various statistics' do
       expect(Gitlab::Metrics::System).to receive(:memory_usage)