True Parallelism in Node.js / Javascript?

const sleep = (ms) => new Promise((resolve) => { setTimeout(resolve, ms) })

async function dbQuery() {
  const start = Date.now();
  await sleep(1000);
  const end = Date.now();
  console.log(end - start);
}

async function main() {
  const list = [1, 2, 3];
  const promises = list.map(m => dbQuery(m));
  await Promise.all(promises);
}

main();

Output:

node-space node is-parallel.js
1003
1009
1009

I want to dbQuery function to be executed at same time when invoke all 3 promises. Now i’m invoking them and pushing into the array and awaiting them, I believe it is not truly parallel, it like calling each function and pushing it to array in serial fashion.

sleep function i have added is just so simulate something async.

>Solution :

Async code in Javascript allows interleaving of code execution, but not parallel execution.

Parallelism can be achieved in Node using the worker threads built-in module. If you want a web standard solution, you could also user Web Workers.