node-worker-threads-pool

node-worker-threads-pool

Simple worker threads pool using Node's worker_threads module.

Notification

1. This module can only run in Node.js.
2. Since Node's worker_threads module is still in stage of Experimental, this module can be accessed only if the --experimental-worker flag is added.

Installation

npm install node-worker-threads-pool --save

Example

Run the example

npm run example

In the worker.js :

const { parentPort } = require('worker_threads');

// Something you shouldn't run in main thread
// since it will block the main thread.
function fib(n) {
  if (n < 2) {
    return n;
  }
  return fib(n - 1) + fib (n - 2);
}

// Main thread will pass the data you need
// through this event listener.
parentPort.on('message', param => {
  if (typeof param !== 'number') {
    throw new Error('param must be a number.');
  }
  const result = fib(param);

  // return the result to main thread.
  parentPort.postMessage(result);
});

In the main.js :

const Pool = require('node-worker-threads-pool');

const filePath = 'absolute/path/to/your/worker/script';
const num = 4; // The number of workers in this pool.
const pool = new Pool(filePath, num);

for (let i = 0; i < 20; i++) {
  (async () => {
    const num = 40 + Math.trunc(10 * Math.random());

    // This will choose one idle worker in the pool
    // to execute your heavy task without blocking
    // the main thread!
    const res = await pool.exec(num);
    
    console.log(`Fibonacci(${num}) result:`, res);
  })();
}

API

new Pool(filePath, num)

• filePath - The absolute path of your worker.js file.
• num - The number of the workers in your pool.

pool.exec(data)

• data - The data your worker script need.
• Returns: <Promise>

Choose one idle worker in the pool to execute your heavy task with the data you provided. The Promise is resolved with the result your worker generated.

pool.destroy()

Call worker.terminate() for every worker in the pool and release them.

License

node-worker-threads-pool is licensed under the GNU General Public License v3 (GPL-3) (http://www.gnu.org/copyleft/gpl.html).