https://github.com/carstenbauer/littlebookofsemaphores.jl

Julia code snippets inspired by the Little Book Of Semaphores
https://github.com/carstenbauer/littlebookofsemaphores.jl

Last synced: about 1 month ago
JSON representation

Julia code snippets inspired by the Little Book Of Semaphores

• Host: GitHub
• URL: https://github.com/carstenbauer/littlebookofsemaphores.jl
• Owner: carstenbauer
• Created: 2024-03-17T17:55:42.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2024-03-21T12:14:59.000Z (9 months ago)
• Last Synced: 2024-10-13T22:32:24.883Z (2 months ago)
• Language: Julia
• Size: 18.6 KB
• Stars: 5
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

        
## The book

[The Little Book Of Semaphores](https://greenteapress.com/wp/semaphores/) is available for free in PDF form.

## General notes

Julia's `Semaphore` is different from the one described in the book in that it has extra constraints:

- `Semaphore(sem_size > 0)`, i.e. you can't create a `Semaphore(0)`.

- The number of releases (signal) and acquires (wait) must match.

For this reason, we cannot implement the examples with `Semaphore` without further ado.

In Julia, most of the time you don't use a `Semaphore` directly. Instead, you can use a lock (`ReentrantLock`), which corresponds to a `Semaphore(1)`, and a `Threads.Condition` for what is done with "`Semaphore(0)`" in the book.

## Files

- `barrier.jl`: A simple barrier at which all participating tasks wait for each other before moving on.

- `producer_consumer.jl`: Producer tasks produce elements (in parallel) and independent consumer tasks process them (in parallel). Can be used/generalized for pipelining.

- `readers_writers.jl`: "Critical" section with categorical mutual exclusion of reader tasks (non-exclusive access) and writer tasks (exclusive access). The simpler case of a purely exclusive critical section is not covered because it can simply be realized with a lock.

- `dining_philosophers.jl`: Avoid circular synchronization deadlock appearing in the [Dining philosophers problem](https://en.wikipedia.org/wiki/Dining_philosophers_problem) formulated by Dijkstra.

- `h2o.jl`: U.C. Berkeley exercise in which two kinds of tasks, hydrogen and oxygen, should pair up such that they can pass a barrier as complete H₂O molecules (2 H + 1 O → H₂O).