Philosophers

Dining philosophers problem

The aim of this project is to learn the basics of threading a process and get familiar with shared memory, threads, mutex, semaphore.

Rules

• A number of philosophers are sitting at a round table doing one of three things: eating, thinking or sleeping.
• While eating, they are not thinking or sleeping, while sleeping, they are not eating or thinking and of course, while thinking, they are not eating 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 eat with a single fork, it is assumed that a philosopher must 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.
• Philosophers should avoid to die!

Each program completes the task using different methods:

• philo_one: threads and mutex
• philo_two: threads and semaphores
• philo_three: processes and semaphores

Build

git clone https://github.com/FrenkenFlores/Philosophers
cd Philosophers
make

Instructions

cd philo_one/
./philo_one number_of_philosophers time_to_die time_to_eat time_to_sleep [number_of_times_each_philosopher_must_eat]

• number_of_philosophers: is the number of philosophers and also the number of forks
• time_to_die: is in milliseconds, if a philosopher doesn’t start eating ’time_to_die’ milliseconds after starting his last meal or the beginning of the simulation, it dies
• time_to_eat: is in milliseconds and is the time it takes for a philosopher to eat. During that time he will need to keep the two forks.
• time_to_sleep: is in milliseconds and is the time the philosopher will spend sleeping.
• number_of_times_each_philosopher_must_eat: argument is optional, if all philosophers eat at least ’number_of_times_each_philosopher_must_eat’ the simulation will stop. If not specified, the simulation will stop only at the death of a philosopher.

Demonstration

Resources

• https://hpc.llnl.gov/training/tutorials/introduction-parallel-computing-tutorial
• https://computing.llnl.gov/tutorials/pthreads/
• https://habr.com/ru/post/326138/
• http://www.usingcsp.com/cspbook.pdf
• https://www.cs.utexas.edu/users/EWD/ewd03xx/EWD310.PDF
• https://www.cs.utexas.edu/users/misra/scannedPdf.dir/DrinkingPhil.pdf
• https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.bpxbd00/ptcrea.htm
• http://www.ccfit.nsu.ru/~kireev/lab1/lab1time.htm
• http://www.csc.villanova.edu/~mdamian/threads/posixsem.html
• https://linux.die.net/man/7/sem_overview