Dining philosophers in golang (I have other impls in Rust, Scala, Scala+Cats effect here)

dining.go

package main

import (
	"fmt"
	"math/rand"
	"sync"
	"time"
	"unsafe"
)

type Chopstick struct {
	mutex sync.Mutex
}

type Philosopher struct {
	name  string
	left  *Chopstick
	right *Chopstick
}

func (p *Philosopher) pickUpForks() {
	// Choose the smaller ID fork first to avoid deadlock
	if uintptr(unsafe.Pointer(&p.left.mutex)) < uintptr(unsafe.Pointer(&p.right.mutex)) {
		p.left.mutex.Lock()
		p.right.mutex.Lock()
	} else {
		p.right.mutex.Lock()
		p.left.mutex.Lock()
	}
	fmt.Printf("%s is picking up forks\n", p.name)
}

func (p *Philosopher) eat() {
	fmt.Println(p.name, "is eating")
	sleepTime := time.Duration(rand.Intn(400)+400) * time.Millisecond
	fmt.Printf("%s is sleeping for %v\n", p.name, sleepTime)
	time.Sleep(sleepTime)
	fmt.Println(p.name, "is done eating")
}

func (p *Philosopher) putDownForks() {
	p.left.mutex.Unlock()
	p.right.mutex.Unlock()
}

func dine(p *Philosopher, wg *sync.WaitGroup) {
    defer wg.Done()
    defer p.putDownForks()

    p.pickUpForks()
    p.eat()
}

func main() {
	forkCount := 5

	forks := make([]*Chopstick, forkCount)
	for i := range forks {
		forks[i] = &Chopstick{}
	}

	philosophers := make([]*Philosopher, forkCount)
	for i := range philosophers {
		left := forks[i]
		right := forks[(i+1)%forkCount]
		philosophers[i] = &Philosopher{fmt.Sprintf("Philosopher %d", i), left, right}
	}

	var wg sync.WaitGroup
	wg.Add(len(philosophers))

	for _, p := range philosophers {
		go dine(p, &wg)
	}

	wg.Wait()

	fmt.Println("All philosophers have eaten")
}

Output

Philosopher 2 is picking up forks
Philosopher 2 is eating
Philosopher 0 is picking up forks
Philosopher 0 is eating
Philosopher 2 is sleeping for 442ms
Philosopher 0 is sleeping for 490ms
Philosopher 2 is done eating
Philosopher 3 is picking up forks
Philosopher 3 is eating
Philosopher 3 is sleeping for 783ms
Philosopher 0 is done eating
Philosopher 1 is picking up forks
Philosopher 1 is eating
Philosopher 1 is sleeping for 704ms
Philosopher 1 is done eating
Philosopher 3 is done eating
Philosopher 4 is picking up forks
Philosopher 4 is eating
Philosopher 4 is sleeping for 426ms
Philosopher 4 is done eating
All philosophers have eaten