execute test files concurrently

app/controllers/concerns/submission_scoring.rb

@@ -1,17 +1,30 @@
+require 'concurrent/future'
+
 module SubmissionScoring
-  def execute_test_files(submission)
+  def collect_test_results(submission)
     submission.collect_files.select(&:teacher_defined_test?).map do |file|
-      output = @docker_client.execute_test_command(submission, file.name_with_extension)
-      output.merge!(@assessor.assess(output))
-      output.merge!(filename: file.name_with_extension, message: output[:score] == Assessor::MAXIMUM_SCORE ? I18n.t('exercises.implement.default_feedback') : file.feedback_message, weight: file.weight)
+      future = Concurrent::Future.execute do
+        assessor = Assessor.new(execution_environment: submission.execution_environment)
+        output = execute_test_file(file, submission)
+        output.merge!(assessor.assess(output))
+        output.merge!(filename: file.name_with_extension, message: feedback_message(file, output[:score]), weight: file.weight)
+      end
+      future.value
     end
   end
-  private :execute_test_files
+  private :collect_test_results
+
+  def execute_test_file(file, submission)
+    DockerClient.new(execution_environment: file.context.execution_environment, user: current_user).execute_test_command(submission, file.name_with_extension)
+  end
+  private :execute_test_file
+
+  def feedback_message(file, score)
+    score == Assessor::MAXIMUM_SCORE ? I18n.t('exercises.implement.default_feedback') : file.feedback_message
+  end
 
   def score_submission(submission)
-    @assessor = Assessor.new(execution_environment: submission.execution_environment)
-    @docker_client = DockerClient.new(execution_environment: submission.execution_environment, user: current_user)
-    outputs = execute_test_files(submission)
+    outputs = collect_test_results(submission)
     score = outputs.map { |output| output[:score] * output[:weight] }.reduce(:+)
     submission.update(score: score)
     outputs