Consider the following monitor solution to the 5 dining philosophers problem where there are 5 chopsticks between 5 philosophers who sit on a round table. A philosopher needs to get both chopsticks on the right and left sides to eat. Suppose the index $i$ is incremented counterclockwise. With the monitor defined below, each philosopher $i$ invokes the operations pickup() and putdown() in the following sequence:

DiningPhilosophers.pickup(i);
    EAT
DiningPhilosophers.putdown(i);

monitor DiningPhilosophers
{
    enum { THINKING, HUNGRY, EATING } state[5];
    condition self[5];
    void pickup(int i) {
        state[i] = HUNGRY;
        test(i);
        if (state[i] != HUNGRY) self[i].wait();
    }

    void putdown(int i) {
        state[i] = THINKING;
        test((i + 4) % 5);
        test((i + 1) % 5);
    }

    void test(int i) {
        if ((state[(i + 4) % 5] != EATING) &&
            (state[i] == HUNGRY) &&
            (state[(i + 1) % 5] != EATING)) {
                state[i] = EATING;
                self[i].signal();
        }
    }

    initialization_code() {
        for (int i = 0; i < 5; i++)
            state[i] = THINKING;
    }
}