Merge branch 'update-allocations-gem-fix-names' into 'master'

Update allocations Gem & ignore classes without names

## What does this MR do?

1. Updates the allocations Gem to 1.0.5 so it can be used on 2.2/2.3 without crashing
2. Changes the background sampler to ignore classes/modules without a name (as we can't do much with these)

## Are there points in the code the reviewer needs to double check?

No.

## Why was this MR needed?

Using MRI 2.2 or 2.3 would lead to a segmentation fault in the allocations Gem, sometimes this problem would also occur on 2.1

## What are the relevant issue numbers?

Not an issue, but the merge request that highlighted these problems: !3807

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- [ ] Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4645

CHANGELOG

@@ -79,6 +79,8 @@ v 8.9.0 (unreleased)
   - Allow users to create confidential issues in private projects
   - Measure CPU time for instrumented methods
   - Instrument private methods and private instance methods by default instead just public methods
+  - Updated the allocations Gem to version 1.0.5
+  - The background sampler now ignores classes without names
 
 v 8.8.5 (unreleased)
   - Ensure branch cleanup regardless of whether the GitHub import process succeeds

Gemfile.lock

@@ -50,7 +50,7 @@ GEM
     after_commit_queue (1.3.0)
       activerecord (>= 3.0)
     akismet (2.0.0)
-    allocations (1.0.4)
+    allocations (1.0.5)
     arel (6.0.3)
     asana (0.4.0)
       faraday (~> 0.9)

lib/gitlab/metrics/sampler.rb

@@ -66,7 +66,11 @@ module Gitlab
         def sample_objects
           sample = Allocations.to_hash
           counts = sample.each_with_object({}) do |(klass, count), hash|
-            hash[klass.name] = count
+            name = klass.name
+
+            next unless name
+
+            hash[name] = count
           end
 
           # Symbols aren't allocated so we'll need to add those manually.

spec/lib/gitlab/metrics/sampler_spec.rb

@@ -72,14 +72,25 @@ describe Gitlab::Metrics::Sampler do
     end
   end
 
-  describe '#sample_objects' do
-    it 'adds a metric containing the amount of allocated objects' do
-      expect(sampler).to receive(:add_metric).
-        with(/object_counts/, an_instance_of(Hash), an_instance_of(Hash)).
-        at_least(:once).
-        and_call_original
+  if Gitlab::Metrics.mri?
+    describe '#sample_objects' do
+      it 'adds a metric containing the amount of allocated objects' do
+        expect(sampler).to receive(:add_metric).
+          with(/object_counts/, an_instance_of(Hash), an_instance_of(Hash)).
+          at_least(:once).
+          and_call_original
+
+        sampler.sample_objects
+      end
 
-      sampler.sample_objects
+      it 'ignores classes without a name' do
+        expect(Allocations).to receive(:to_hash).and_return({ Class.new => 4 })
+
+        expect(sampler).not_to receive(:add_metric).
+          with('object_counts', an_instance_of(Hash), type: nil)
+
+        sampler.sample_objects
+      end
     end
   end