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Polina Vasiuk
Polina Vasiuk

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JavaScript vs. Erlang: A Tale of Two Concurrency Models

Ever wondered how different programming languages handle concurrency? Whether you're optimizing a web server or building a distributed system, choosing the right concurrency model can make or break performance. Two notable examples are JavaScript and Erlang, each designed with unique concurrency models tailored to their primary use cases.

JavaScript​: The Single-Threaded Maestro

JavaScript, particularly in the context of Node.js, operates on a single-threaded event loop. This means it does not natively support 'true' multithreading but achieves concurrency through asynchronous, non-blocking I/O using callbacks, Promises, and async/await.

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To handle CPU-intensive tasks, JavaScript employs:

  • ⚙️ Web Workers (in browsers) or Worker Threads (in Node.js) to create separate threads.
  • 🖥️ Child Processes, which spawn independent processes for parallel execution.

Erlang: The Concurrency King

Erlang, designed for highly concurrent and fault-tolerant systems, follows the Actor Model, where lightweight processes communicate via message passing. The Erlang VM (BEAM) efficiently schedules thousands (or even millions) of these lightweight processes without shared memory, making it highly scalable.

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Key features of Erlang’s concurrency model include:

  • 🔄 Preemptive Scheduling, ensuring fairness across all processes.
  • 📩 Immutable State & Message Passing, reducing the risk of race conditions.
  • 🛡️ Fault Tolerance with Supervision Trees, enabling self-healing systems.

Choosing the Right Tool

  • 🟢 Use JavaScript if your application is primarily I/O-bound, such as web servers handling multiple concurrent requests.
  • 🔵 Use Erlang if you need robust, scalable, and fault-tolerant distributed systems, such as real-time messaging or telecom applications.

Both languages excel in their domains. Understanding their concurrency models is crucial.

How have you tackled concurrency?

Let’s discuss!

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