Quiz crashes when adding a large amount of questions.

Hi,

We have huge quizzes with more than 600 questions each. When we add those 600 questions from the question bank to newly created quiz, the vbo action timeouts (we are stuck with a server on which we cannot modify the PHP timeouts and the PHP-FPM proxy timeout).

However, we tried to add the questions progressively by small groups but the VBO action takes more time each time we add new questions to the quiz and finally we reach our timeout limit again.

I've checked the source and found out that the VBO action responsible for adding questions to the quiz for each question to add :

1. Loads the quiz;
2. Get all the the quiz questions;
3. Loops over the questions to find out if the question is already bound to the quiz;
4. If not, binds the question to the quiz.

So, if I add 200 questions from the question bank to a quiz, for the first question to add, the VBO action will loop over 0 questions, then for the second question over 1 questions, then for the second question over 2 questions, then 3, then 4, ... Which in the end will make (if my maths are correct) 20100 loops over the quiz questions to check if they are not already bound to the quiz...

Anyway, we come up with a solution using drupal static in the VBO action. We "cache" the quiz and its questions so that for each question to add, we don't have to load and loop over all the questions again.

The patch is attached.

Best Regards,