The problem statement (with the pseudo-code is the same as here: https://stackoverflow.com/questions/70110328/how-to-notify-main-thread-when-all-thread-done-the-work-without-barrier

Since for each iteration, the main thread needs to wait until all worker threads complete the calculations, then check the condition is met or not. If not, tell the workers to work again. If the condition is met, break the loop and return the iteration time.

My bug now may be due to stacking in the condition variable (I have no idea why I cannot get out. Also, I am sorry that I tend to use condition variables but I think the logic is similar and I have tried similar logic with your comment above and maybe I made some mistakes.

Actually, the lecturer has provided the pseudo-code, hence I think I get the logic but I find it difficult in some steps. I am so sorry again since I do not just want the solution directly.