是否可以在 NodeJS 中使用带有工作线程的服务？

Question

I'm coding in NodeJS, I'm trying to make an API service which use multithreading internally, I've read many worker-threads tutorials, but I haven't found a solution.

In classes/controller.js:

const { Worker, isMainThread, parentPort, workerData } = require('worker_threads');
const os = require('os');
...
var threadN = function()
{
    if (isMainThread)
    {
        module.exports = function parseJSAsync(script)
        {
            return new Promise
            (
                (resolve, reject) =>
                {
                    const worker = new Worker(filename, {workerData: script});
                    worker.on('message', resolve);
                    worker.on('error', reject);
                    worker.on
                    (
                        'exit',
                        (code) =>
                        {
                            if (code !== 0)
                            {
                                reject(new Error(`Worker stopped with exit code ${code}`));
                            }
                        }
                    );
                }
            );
        };
        console.log('Thread ID:       ', Worker.threadId, "\nNumber of CPU's:", os.cpus().length);
    }
    else
    {
        console.log('Thread ID:       ', Worker.threadId, "\nNumber of CPU's:", os.cpus().length);
        const { parse } = require('some-js-parsing-library');
        const script = workerData;
        parentPort.postMessage(parse(script));
    }
};
...
exports.threadTest = function (req, res)
{
    threadN();
    res.json
    ({
        status: true,
        message: 'Hello World!'
    });
};

In routes/routes.js

var app = express();
...
app.get("/api_1.0/threadtest", model.threadTest);
...

When I consume it in Postman and see console changes I must get four messages (my CPU has four cores) with four thread ids, otherwise I got this:

How can I consume an API service with worker_thread correctly?

Answer 1

Is it possible to consume a service with worker threads in NodeJS?

Yes, if the worker thread and route for calling it is written properly.

There are a number of things wrong here:

1. You call threadN() in your route, but all that does in the main thread is assign parseJSAsync to module.exports . It doesn't actually call anything in another thread or even create another thread. It doesn't call parseJSAsync() .
2. Assigning something to module.exports long after the module has been initialized is an anti-pattern that probably doesn't do anything useful. Any importing module already looked for what it might find in the exports, long before you assigned parseJSAsync to it.
3. In threadTest() , you call threadN() , but that doesn't do anything useful for processing the request. It seems more like you need to be calling parseJSAsync() and then using the promise that it returns.

On a personal style note, I find workerThread code a ton easier to understand and work on if I put the mainThread code and workerThread code in separate files. Then there's no context needed within the file in order to know which code is which. IMO, it is a ton easier to understand and follow. I know that node.js documentation examples tend to use the single file approach, but after trying it, I moved to separate files as it was so much easier to work on, debug and understand.