5.8 The roller coaster problem This problem is from Andrews’s Concurrent Programming [1], but he attributes it to J. S. Herman’s Master’s thesis. Suppose there are n passenger threads and a car thread. The passengers repeatedly wait to take rides in the car, which can hold C passengers, where C < n. The car can go around the tracks only when it is full. Here are some additional details: • Passengers should invoke board and unboard. • The car should invoke load, run and unload. • Passengers cannot board until the car has invoked load • The car cannot depart until C passengers have boarded. • Passengers cannot unboard until the car has invoked unload. Puzzle: Write code for the passengers and car that enforces these constraints.
5.8.3 Multi-car Roller Coaster problem This solution does not generalize to the case where there is more than one car. In order to do that, we have to satisfy some additional constraints: • Only one car can be boarding at a time. • Multiple cars can be on the track concurrently. • Since cars can’t pass each other, they have to unload in the same order they boarded. • All the threads from one carload must disembark before any of the threads from subsequent carloads. Puzzle: modify the previous solution to handle the additional constraints. You can assume that there are m cars, and that each car has a local variable named i that contains an identifier between 0 and m − 1.
simulation of code on the above code in the link below https://www.youtube.com/watch?v=X4MdaWIQv_o&t=135s
Note that currently the code only works with python 2 may upgrade in future.
If you don't have git already installed you may do so by
sudo apt get install git
Then clone this repo by
git clone https://github.com/devarshi16/Multicoaster-Semaphore
Change directory into the cloned repository
cd Multicoaster-Semaphore
Install pygame(for the graphics)
pip install pygame
Run the code
python multicoaster.py