sidekiq-cluster: put each sidekiq in a new pgroup

We now kill the whole process group for termination signals

ee/changelogs/unreleased/ce-40396-sidekiq-cluster-pgroups.yml

+---
+title: 'sidekiq-cluster: put each sidekiq in a new pgroup'
+merge_request: 9775
+author:
+type: other

ee/lib/gitlab/sidekiq_cluster.rb

@@ -56,7 +56,7 @@ module Gitlab
     #     start([ ['foo'], ['bar', 'baz'] ], :production)
     #
     # This would start two Sidekiq processes: one processing "foo", and one
-    # processing "bar" and "baz".
+    # processing "bar" and "baz". Each one is placed in its own process group.
     #
     # queues - An Array containing Arrays. Each sub Array should specify the
     #          queues to use for a single process.
@@ -92,6 +92,7 @@ module Gitlab
       pid = Process.spawn(
         { 'ENABLE_SIDEKIQ_CLUSTER' => '1' },
         *cmd,
+        pgroup: true,
         err: $stderr,
         out: $stdout
       )

ee/spec/lib/gitlab/sidekiq_cluster_spec.rb

@@ -79,6 +79,7 @@ describe Gitlab::SidekiqCluster do
 
   describe '.start_sidekiq' do
     let(:env) { { "ENABLE_SIDEKIQ_CLUSTER" => "1" } }
+    let(:args) { ['bundle', 'exec', 'sidekiq', anything, '-eproduction', *([anything] * 5)] }
 
     it 'starts a Sidekiq process' do
       allow(Process).to receive(:spawn).and_return(1)
@@ -88,13 +89,24 @@ describe Gitlab::SidekiqCluster do
     end
 
     it 'handles duplicate queue names' do
-      allow(Process).to receive(:spawn)
-                    .with(env, "bundle", "exec", "sidekiq", "-c 5", "-eproduction", "-gqueues: foo (2), bar, baz", anything, "-qfoo,2", "-qbar,1", "-qbaz,1", anything)
-                    .and_return(1)
+      allow(Process)
+        .to receive(:spawn)
+        .with(env, *args, anything)
+        .and_return(1)
 
       expect(described_class).to receive(:wait_async).with(1)
       expect(described_class.start_sidekiq(%w(foo foo bar baz), :production)).to eq(1)
     end
+
+    it 'runs the sidekiq process in a new process group' do
+      expect(Process)
+        .to receive(:spawn)
+        .with(anything, *args, a_hash_including(pgroup: true))
+        .and_return(1)
+
+      allow(described_class).to receive(:wait_async)
+      expect(described_class.start_sidekiq(%w(foo bar baz), :production)).to eq(1)
+    end
   end
 
   describe '.wait_async' do