Overview

The dining$-$philosophers problem is considered a classic

synchronization problem neither because of its practical

importance nor because computer scientists dislike philosophers

but because it is an example of a large class of concurrency$-$

control problems. ${?}^1$

Consider five philosophers who spend their lives thinking and

eating. The philosophers share a circular table surrounded by

five chairs, each belonging to one philosopher. In the center of

the table is a bowl of rice, and the table is laid with five

single chopsticks $($Figure $7\mathrm{.}5).$ When a philosopher thinks, she

does not interact with her colleagues. From time to time, a

philosopher gets hungry and tries to pick up the two chopsticks

that are closest to her $($the chopsticks that are between her and

her left and right neighbors$).$ A philosopher may pick up only

one chopstick at a time. Obviously, she cannot pick up a

chopstick that is already in the hand of a neighbor. When a

hungry philosopher has both her chopsticks at the same time, she

eats without releasing the chopsticks. When she is finished

eating, she puts down both chopsticks and starts thinking again. ${?}^1$

Figure $7\mathrm{.}5$ The situation of the dining philosophers.

Implementation

Use semaphores to implement the solution of the Dining$-$

Philosophers Problem