Understanding Concurrency in Rust: A Comprehensive Guide | RustMeUp

Understanding Concurrency in Rust: A Comprehensive Guide

In computer software, concurrency deals with executing multiple tasks simultaneously. Rust, a potent and reliable programming language, offers fantastic support for writing concurrent programs due to its strong memory safety guarantees and data race protection. In this comprehensive guide, we explore the fundamentals of Concurrency in Rust while outlining how to implement and manage multi-threading, shared states, and other crucial concurrency concepts.

What is Concurrency?

Before diving deeper, let's define what concurrency is. Concurrency stems from the ability of a computer system to execute several tasks or processes in overlapping time intervals. In programming, it forms a crucial part of writing efficient and scalable programs.

Concurrency doesn't always mean performing multiple tasks at the single instant—this would require parallelism, a subset of concurrency. Instead, we can think of it like multitasking, where tasks switch in and out during execution time. The main objective is to break down complex programs into several independent subprocesses, called threads.

Rust's Approach to Concurrency

Designed with an eye on safety and speedy performance, Rust has some explicit choices that make handling concurrency markedly easier and safer. In contrast with traditional languages that leave concurrency management entirely on the programmer and the operating system, Rust provides out-of-the-box abstractions.

Fearless Concurrency

In Rust, concurrency is safe and efficient due to what it terms fearless concurrency. Fearless concurrency in Rust means it ensures abstractions that are both safe from data races and efficient at runtime. Its primitives for thread-spawn handling, inter-thread communication, and mutual exclusion for shared states foster the spirit of fearless concurrency.

Ownership and Borrowing

Rust only allows one mutable reference or any number of immutable references to a piece of data in a particular scope. This ensures data races cannot occur, as they require simultaneous access to shared memory.

Message Passing

Message Passing is a popular technique in concurrent programming where we pass messages, rather than sharing state. Rust implemented the "communicate by sharing memory" slogan in the form of channels which are similar to real-world channels.

Thread Spawning

Rust provides the std::thread::spawn method to create new OS threads.

Multi-threading in Rust

Multi-threading is one of the essential aspects of concurrency. It allows a single process to split itself into multiple simultaneously executing tasks or threads. Here's a brief look at how this is achieved in Rust:

use std::thread;
use std::time::Duration;

fn main() {
    thread::spawn(|| {
        for i in 1..10 {
            println!("hi number {} from the spawned thread!", i);

    for i in 1..5 {
        println!("hi number {} from the main thread!", i);

Shared-State Concurrency

Shared-state is another crucial aspect of concurrency in Rust. Rust discourages sharing mutable state by employing ownership, borrowing, and dropping paradigms. However, for concurrent scenarios where shared mutable state might be necessary, Rust uses mutexes. Mutex stands for "mutual exclusion," meaning that by locking a mutex, the thread prevents other threads from accessing the underlying data until it has finished using it.


The Rust programming language has unique features and techniques for handling concurrency, making it a compelling choice for concurrent programming tasks. Its paradigm of "fearless concurrency" simplifies multi-threading and shared-state management while avoiding common pitfalls like data races.

The world of concurrency in Rust is vast—there are more concepts to explore and fully understand, such as channels for message passing concurrency, atomic reference counting (Arc), and many others. Hopefully, this comprehensive guide gives you a well-rounded understanding of the value and the potential of Rust in concurrent programming. Let's continue exploring, learning, and Rusting!