Resolve timeout in admin/jobs

app/controllers/admin/jobs_controller.rb

 # frozen_string_literal: true
 
 class Admin::JobsController < Admin::ApplicationController
+  BUILDS_PER_PAGE = 30
+
   def index
     # We need all builds for tabs counters
     @all_builds = Ci::JobsFinder.new(current_user: current_user).execute
@@ -8,7 +10,7 @@ class Admin::JobsController < Admin::ApplicationController
     @scope = params[:scope]
     @builds = Ci::JobsFinder.new(current_user: current_user, params: params).execute
     @builds = @builds.eager_load_everything
-    @builds = @builds.page(params[:page]).per(30)
+    @builds = @builds.page(params[:page]).per(BUILDS_PER_PAGE).without_count
   end
 
   def cancel_all

changelogs/unreleased/lm-resolve-timeout.yml

+---
+title: Resolve timeout in admin/jobs
+merge_request: 35385
+author:
+type: fixed

spec/controllers/admin/jobs_controller_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Admin::JobsController do
+  describe 'GET #index' do
+    context 'with an authenticated admin user' do
+      it 'paginates builds without a total count', :aggregate_failures do
+        stub_const("Admin::JobsController::BUILDS_PER_PAGE", 1)
+
+        sign_in(create(:admin))
+        create_list(:ci_build, 2)
+
+        get :index
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(assigns(:builds)).to be_a(Kaminari::PaginatableWithoutCount)
+        expect(assigns(:builds).count).to be(1)
+      end
+    end
+
+    context 'without admin access' do
+      it 'returns `not_found`' do
+        sign_in(create(:user))
+
+        get :index
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+  end
+end