threadwork

Simple, no frills, threading in Node.js

Why

Other solutions were too complex. Many threading apps just need a way to create a thread pool and call the threaded function; that's what this does.

How

Most threading solutions stringify the function and arguments before passing them to a worker. Stringifying creates friction when using dependencies. threadwork skips stringifying the function by using a reference instead, reducing the effort to create a threaded function.

Example

// fibonacci.js
const { ThreadPool } = require('threadwork');

function fibonacci(n) {
	if (n < 2) return n;
	return fibonacci(n - 1) + fibonacci(n - 2);
}

module.exports = new ThreadPool({ task: fibonacci });

// index.js
const pool = require('./fibonacci');

(async () => {
	try {
		const results = await Promise.all([
			pool.run(10),
			pool.run(20),
			pool.run(30)
		]);
		console.log(results); // [55, 6765, 832040]
	} catch (e) {
		console.log(e);
	} finally {
		await pool.close();
	}
})();

API

• new ThreadPool({ task, size }) - The primary class. It should be instantiated at the top-level and only once per file.

  • task - The worker runs this function
  • size - The number of workers in the pool (defaults to the number of cores)

• await pool.run(arg1, arg2, ...) - Executes the task once with the arguments provided.

• await pool.close() - Terminates all the workers, allowing the process to exit.

• pool.isMainThread - Allows logic based on whether we're in a worker or not.

Compatibility

Node.js 12+ for stable worker_threads

ts-node-dev

There's best-effort support for ts-node-dev. You must provide the following:

1. TS_NODE_DEV_CACHE as an environment variable
2. The same directory should be provided to ts-node-dev via --cache-directory

CLI example:

TS_NODE_DEV_CACHE=.ts-node tsnd --cache-directory $TS_NODE_DEV_CACHE --respawn index.ts

License

MIT

See also

• workerpool
• node-worker-threads-pool
• piscina