[SDTEST-744] add memory leaks tests with ruby_memcheck

.github/workflows/test-memory-leaks.yml

@@ -0,0 +1,15 @@
+name: Test for memory leaks
+on: [push]
+jobs:
+  test-memcheck:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.4.0-preview1 # TODO: Use stable version once 3.4 is out
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+          bundler: latest
+          cache-version: v1 # bump this to invalidate cache
+      - run: sudo apt-get update && (sudo apt-get install -y valgrind || sleep 5 && sudo apt-get install -y valgrind) && valgrind --version
+      - run: bundle exec rake compile spec:ddcov_memcheck

Gemfile

@@ -33,12 +33,14 @@ gem "pimpmychangelog", ">= 0.1.2"
 gem "simplecov"
 gem "simplecov-cobertura", "~> 2.1.0"
 
-# type checking
+# type checks, memory checks, etc.
 group :check do
   if RUBY_VERSION >= "3.0.0" && RUBY_PLATFORM != "java"
     gem "rbs", "~> 3.5.0", require: false
     gem "steep", "~> 1.7.0", require: false
   end
+
+  gem "ruby_memcheck", ">= 3" if RUBY_VERSION >= "3.4.0" && RUBY_PLATFORM != "java"
 end
 
 # development dependencies for vscode integration and debugging

Rakefile

@@ -7,6 +7,19 @@ require "rspec/core/rake_task"
 require "yard"
 require "rake/extensiontask"
 
+if Gem.loaded_specs.key? "ruby_memcheck"
+  require "ruby_memcheck"
+  require "ruby_memcheck/rspec/rake_task"
+
+  RubyMemcheck.config(
+    # If there's an error, print the suppression for that error, to allow us to easily skip such an error if it's
+    # a false-positive / something in the VM we can't fix.
+    valgrind_generate_suppressions: true,
+    # This feature provides better quality data -- I couldn't get good output out of ruby_memcheck without it.
+    use_only_ruby_free_at_exit: true
+  )
+end
+
 RSpec::Core::RakeTask.new(:spec)
 
 Dir.glob("tasks/*.rake").each { |r| import r }
@@ -159,6 +172,19 @@ namespace :spec do
     t.pattern = "spec/datadog/ci/git/**/*_spec.rb"
     t.rspec_opts = args.to_a.join(" ")
   end
+
+  # ddcov test impact analysis tool with memcheck
+  desc ""
+  if Gem.loaded_specs.key?("ruby_memcheck")
+    RubyMemcheck::RSpec::RakeTask.new(:ddcov_memcheck) do |t, args|
+      t.pattern = "spec/ddcov/**/*_spec.rb"
+      t.rspec_opts = args.to_a.join(" ")
+    end
+  else
+    task :ddcov_memcheck do
+      raise "Memcheck requires the ruby_memcheck gem to be installed"
+    end
+  end
 end
 
 desc "CI task; it runs all tests for current version of Ruby"

spec/datadog/ci/release_gem_spec.rb

@@ -46,6 +46,7 @@
             |tasks
             |yard
             |vendor/rbs
+            |suppressions
           )/
         }x
 

suppressions/ruby-3.4.supp

@@ -0,0 +1,53 @@
+# This is a valgrind suppression configuration file.
+#
+# We use it together with the ruby_memcheck gem to find issues in the datadog-ci-rb native extensions; in some cases
+# we need to ignore potential issues as they're not something we can fix (e.g. outside our code.)
+#
+# See https://valgrind.org/docs/manual/manual-core.html#manual-core.suppress for details.
+
+# When a Ruby process forks, it looks like Ruby doesn't clean up the memory of old threads?
+{
+  ruby-native-thread-memory
+  Memcheck:Leak
+  fun:calloc
+  fun:calloc1
+  fun:rb_gc_impl_calloc
+  fun:native_thread_alloc
+  fun:native_thread_create_dedicated
+  fun:native_thread_create
+  fun:thread_create_core
+  ...
+}
+
+# When a Ruby process forks, it looks like Ruby doesn't clean up the memory of old threads?
+{
+  ruby-native-thread-memory-2
+  Memcheck:Leak
+  fun:calloc
+  fun:calloc1
+  fun:objspace_xcalloc
+  fun:ruby_xcalloc_body
+  fun:native_thread_alloc
+  fun:native_thread_create_dedicated
+  fun:native_thread_create
+  fun:thread_create_core
+  ...
+}
+
+# We don't care about the pkg-config external tool
+{
+  pkg-config-memory
+  Memcheck:Leak
+  ...
+  obj:/usr/bin/pkg-config
+  ...
+}
+
+# We don't care about the tr external tool
+{
+  pkg-config-memory
+  Memcheck:Leak
+  ...
+  obj:/usr/bin/tr
+  ...
+}