Philosophers

Implementation of the classic dining philosophers problem using POSIX threads and mutexes.

Description

philosophers simulates N philosophers sitting at a round table, each alternating between thinking, picking up forks, eating, and putting down forks. The challenge is to prevent deadlocks and starvation while correctly detecting when a philosopher has died.

Rules

• Each philosopher is a thread
• Each fork is a mutex shared between two adjacent philosophers
• A philosopher dies if they have not eaten within time_to_die milliseconds
• The simulation stops when one philosopher dies, or when all have eaten number_of_times times (optional)

Usage

make
./philo <number_of_philosophers> <time_to_die> <time_to_eat> <time_to_sleep> [number_of_times_each_philosopher_must_eat]

Example:

./philo 5 800 200 200

Architecture

main → parse args → init forks (mutexes) → init philosophers (threads)
     → each thread: loop { think → lock forks → eat → unlock → sleep }
     → monitor thread: check timestamps → detect death → stop all

Stack

• Language: C
• Key concepts: POSIX threads (pthread_create, pthread_join), mutexes (pthread_mutex_t), race conditions, deadlock prevention

42 Project Info

Field	Value
Project	Philosophers
Circle	3
Norminette	Compliant

What I Learned

• Thread lifecycle management with pthread_create and pthread_join
• Mutex locking strategies to avoid deadlocks
• Precise timing with gettimeofday and usleep
• Detecting race conditions and data races