How to create threads in nodejs

Question

Is there any way to create threads for running multiple methods at a time?

That way, if any method fails in between all the other threads should be killed.

Answer 1

New answer: While node.js didn't used to have the ability to use threading natively, the ability has since been added. See https://nodejs.org/api/worker_threads.html for details.

Old answer: Every node.js process is single threaded by design. Therefore to get multiple threads, you have to have multiple processes (As some other posters have pointed out, there are also libraries you can link to that will give you the ability to work with threads in Node, but no such capability exists without those libraries. See answer by Shawn Vincent referencing https://github.com/audreyt/node-webworker-threads)

You can start child processes from your main process as shown here in the node.js documentation: http://nodejs.org/api/child_process.html. The examples are pretty good on this page and are pretty straight forward.

Your parent process can then watch for the close event on any process it started and then could force close the other processes you started to achieve the type of one fail all stop strategy you are talking about.

Also see: Node.js on multi-core machines

Answer 2

There is also at least one library for doing native threading from within Node.js: node-webworker-threads

https://github.com/audreyt/node-webworker-threads

This basically implements the Web Worker browser API for node.js.

Answer 3

Update 2:

Since Node.js 12 LTS Worker threads are stable.

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Update 1:

From Node v11.7.0 onward, you do not have to use --experimental-worker flag.

Release note: https://nodejs.org/en/blog/release/v11.7.0/

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From Node 10.5 there is now multi threading support, but it is experimental. Hope this will become stable soon.

Checkout following resources :

• PR thread.
• Official Documentation
• Blog article: Threads in Node 10.5.0: a practical intro

Answer 4

You can get multi-threading using Napa.js.

https://github.com/Microsoft/napajs

"Napa.js is a multi-threaded JavaScript runtime built on V8, which was originally designed to develop highly iterative services with non-compromised performance in Bing. As it evolves, we find it useful to complement Node.js in CPU-bound tasks, with the capability of executing JavaScript in multiple V8 isolates and communicating between them. Napa.js is exposed as a Node.js module, while it can also be embedded in a host process without Node.js dependency."

Answer 5

I needed real multithreading in Node.js and what worked for me was the threads package. It spawns another process having it's own Node.js message loop, so they don't block each other. The setup is easy and the documentation get's you up and running fast. Your main program and the workers can communicate in both ways and worker "threads" can be killed if needed.

Since multithreading and Node.js is a complicated and widely discussed topic it was quite difficult to find a package that works for my specific requirement. For the record these did not work for me:

• tiny-worker allowed spawning workers, but they seemed to share the same message loop (but it might be I did something wrong - threads had more documentation giving me confidence it really used multiple processes, so I kept going until it worked)
• webworker-threads didn't allow require-ing modules in workers which I needed

And for those asking why I needed real multi-threading: For an application involving the Raspberry Pi and interrupts. One thread is handling those interrupts and another takes care of storing the data (and more).

Answer 6

The nodejs 10.5.0 release has announced multithreading in Node.js. The feature is still experimental. There is a new worker_threads module available now.

You can start using worker threads if you run Node.js v10.5.0 or higher, but this is an experimental API. It is not available by default: you need to enable it by using  --experimental-worker when invoking Node.js.

Here is an example with ES6 and worker_threads enabled, tested on version 12.3.1

//package.json

  "scripts": {
  "start": "node  --experimental-modules --experimental- worker index.mjs"
  },

Now, you need to import Worker from worker_threads. Note: You need to declare you js files with '.mjs' extension for ES6 support.

//index.mjs
import { Worker } from 'worker_threads';

const spawnWorker = workerData => {
    return new Promise((resolve, reject) => {
        const worker = new Worker('./workerService.mjs', { workerData });
        worker.on('message', resolve);
        worker.on('error', reject);
        worker.on('exit', code => code !== 0 && reject(new Error(`Worker stopped with 
        exit code ${code}`)));
    })
}

const spawnWorkers = () => {
    for (let t = 1; t <= 5; t++)
        spawnWorker('Hello').then(data => console.log(data));
}

spawnWorkers();

Finally, we create a workerService.mjs

//workerService.mjs
import { workerData, parentPort, threadId } from 'worker_threads';

// You can do any cpu intensive tasks here, in a synchronous way
// without blocking the "main thread"
parentPort.postMessage(`${workerData} from worker ${threadId}`);

Output:

npm run start

Hello from worker 4
Hello from worker 3
Hello from worker 1
Hello from worker 2
Hello from worker 5

Answer 7

If you're using Rx, it's rather simple to plugin in rxjs-cluster to split work into parallel execution. (disclaimer: I'm the author)

https://www.npmjs.com/package/rxjs-cluster

Answer 8

There is also now https://github.com/xk/node-threads-a-gogo, though I'm not sure about project status.

Answer 9

NodeJS now includes threads (as an experimental feature at time of answering).

Answer 10

You might be looking for Promise.race (native I/O racing solution, not threads)

Assuming you (or others searching this question) want to race threads to avoid failure and avoid the cost of I/O operations, this is a simple and native way to accomplish it (which does not use threads). Node is designed to be single threaded (look up the event loop), so avoid using threads if possible. If my assumption is correct, I recommend you use Promise.race with setTimeout (example in link). With this strategy, you would race a list of promises which each try some I/O operation and reject the promise if there is an error (otherwise timeout). The Promise.race statement continues after the first resolution/rejection, which seems to be what you want. Hope this helps someone!

Answer 11

Node.js doesn't use threading. According to its inventor that's a key feature. At the time of its invention, threads were slow, problematic, and difficult. Node.js was created as the result of an investigation into an efficient single-core alternative. Most Node.js enthusiasts still cite ye olde argument as if threads haven't been improved over the past 50 years.

As you know, Node.js is used to run JavaScript. The JavaScript language has also developed over the years. It now has ways of using multiple cores - i.e. what Threads do. So, via advancements in JavaScript, you can do some multi-core multi-tasking in your applications. user158 points out that Node.js is playing with it a bit. I don't know anything about that. But why wait for Node.js to approve of what JavaScript has to offer.

Google for JavaScript multi-threading instead of Node.js multi-threading. You'll find out about Web Workers, Promises, and other things.

Answer 12

You can't run multiple threads natively in node.js, however if you really need to offload some code from the main thread, you can always use child_process fork() to run some code in another process with it's own PID and memory.