Merge branch 'bvl-correct-thread-count' into 'master'

Correct threadcount in multithreaded environments

See merge request gitlab-org/gitlab!25261

changelogs/unreleased/bvl-correct-thread-count.yml

+---
+title: Fix sidekiq jobs not always getting a database connection when running with low concurrency
+merge_request: 25261
+author:
+type: fixed

lib/gitlab/runtime.rb

@@ -78,12 +78,16 @@ module Gitlab
       end
 
       def max_threads
+        main_thread = 1
+
         if puma?
-          Puma.cli_config.options[:max_threads]
+          Puma.cli_config.options[:max_threads] + main_thread
         elsif sidekiq?
-          Sidekiq.options[:concurrency]
+          # An extra thread for the poller in Sidekiq Cron:
+          # https://github.com/ondrejbartas/sidekiq-cron#under-the-hood
+          Sidekiq.options[:concurrency] + main_thread + 1
         else
-          1
+          main_thread
         end
       end
     end

spec/lib/gitlab/runtime_spec.rb

@@ -50,7 +50,7 @@ describe Gitlab::Runtime do
       allow(puma_type).to receive_message_chain(:cli_config, :options).and_return(max_threads: 2)
     end
 
-    it_behaves_like "valid runtime", :puma, 2
+    it_behaves_like "valid runtime", :puma, 3
   end
 
   context "unicorn" do
@@ -71,7 +71,7 @@ describe Gitlab::Runtime do
       allow(sidekiq_type).to receive(:options).and_return(concurrency: 2)
     end
 
-    it_behaves_like "valid runtime", :sidekiq, 2
+    it_behaves_like "valid runtime", :sidekiq, 4
   end
 
   context "console" do