philosophers

This project focuses on the basics of threading a process and how to work on the same memory space. We learnt how to make threads, and discover the mutex, semaphore and shared memory.

Project requirements

• A number of philosophers are sitting at a round table doing one of three things: eating, thinking or sleeping.

• The philosophers sit at a circular table with a large bowl of spaghetti in the center. There are some forks on the table. As spaghetti is difficult to serve and philo_eat with a single fork, it is assumed that a philosopher must philo_eat with two forks, one for each hand.

• The philosophers must never be starving. Every philosopher needs to eat. Philosophers don’t speak with each other. Philosophers don’t know when another philosopher is about to die.

• Each time a philosopher has finished eating, he will drop his forks and start sleeping. When a philosopher is done sleeping, he will start thinking. The simulation stops when a philosopher dies.

philo_one (link)

• One fork between each philosopher, therefore there will be a fork at the right and at the left of each philosopher.

• To avoid philosophers duplicating forks, you should protect the forks state with a mutex for each of them.

• Each philosopher should be a thread.

philo_two (link)

• All the forks are in the middle of the table.

• They have no states in memory but the number of available forks is represented by a semaphore.

• Each philosopher should be a thread.

philo_three (link)

• All the forks are in the middle of the table.

• They have no states in memory but the number of available forks is represented by a semaphore.

• Each philosopher should be a process and the main process should not be a philosopher.

wiki

• You can check my learnings from this project in this wiki

How to test

• These parameters are required in order when running the executable: number_of_philosophers time_to_die time_to_eat time_to_sleep number_of_times_each_philosopher_must_eat(optional)
• Do not test with more than 200 philosophers
• Do not test with time_to_die time_to_eat time_to_sleep under 60ms
• Test with 5 800 200 200, no one should die
• Test with 5 800 200 200 7, the simulation should stop when all the philosophers have eaten at least 7 times each

Run the following commands:

$ git clone https://github.com/qingqingqingli/philosophers
# choose which version you want to test
$ cd philo_one
$ make
$ ./philo_one 5 800 200 200

Examples

When the stimulation does not stop

When philosopher dies