ActiveRecord::StaleObjectError: Attempted to update a stale object: Ci::Build

app/services/ci/register_job_service.rb

@@ -38,11 +38,15 @@ module Ci
         begin
           # In case when 2 runners try to assign the same build, second runner will be declined
           # with StateMachines::InvalidTransition or StaleObjectError when doing run! or save method.
-          build.runner_id = runner.id
-          build.run!
-          register_success(build)
-
-          return Result.new(build, true)
+          begin
+            build.runner_id = runner.id
+            build.run!
+            register_success(build)
+
+            return Result.new(build, true)
+          rescue Ci::Build::MissingDependenciesError
+            build.drop!(:missing_dependency_failure)
+          end
         rescue StateMachines::InvalidTransition, ActiveRecord::StaleObjectError
           # We are looping to find another build that is not conflicting
           # It also indicates that this build can be picked and passed to runner.
@@ -54,9 +58,6 @@ module Ci
           # we still have to return 409 in the end,
           # to make sure that this is properly handled by runner.
           valid = false
-        rescue Ci::Build::MissingDependenciesError
-          build.drop!(:missing_dependency_failure)
-          valid = false
         end
       end
 

spec/services/ci/register_job_service_spec.rb

@@ -307,6 +307,19 @@ module Ci
 
             it_behaves_like 'not pick'
           end
+
+          context 'when job object is staled' do
+            let!(:pre_stage_job) { create(:ci_build, :running, pipeline: pipeline, name: 'test', stage_idx: 0) }
+
+            before do
+              allow_any_instance_of(Ci::Build).to receive(:drop!)
+                .and_raise(ActiveRecord::StaleObjectError.new(pending_job, :drop!))
+            end
+
+            it 'does not drop nor pick' do
+              expect(subject).to be_nil
+            end
+          end
         end
 
         shared_examples 'validation is not active' do