Nodejs worker threads implementation issue

Question

I have a test1.ts file where I was trying to offload some CPU-intensive image manipulation work to worker threads. Below is the code shown for file test1.ts and also its invocation at another file. The project is a nodejs expressjs web server.

test1.ts file

const { Worker, workerData,isMainThread, parentPort } = require("worker_threads");
const { generateUrls } =  require("./util");
const Jimp = require("jimp");
const { uploadImage } =  require("../imageStorage");

if (!isMainThread){
    mainWork()
    .finally(() => {
        parentPort?.postMessage({});
    })
} 

async function mainWork() {
  const { accountId, imageBuffer, imageNames, docUrls, meta } = workerData;

  try {
    const { imageIndex, imageType } = meta;
    const imageName = imageNames.imageName + `_${imageType}_` + `${imageIndex || ""}` + ".png";
    docUrls[imageType === "heatmap" ? "heatmapUrls" : "normalUrls"][imageIndex] = generateUrls(
      accountId,
      imageName
    );

    const maxWidth = 764;
    const maxHeight = 2000;
    const image = await Jimp.read(imageBuffer);
    const originalWidth = image.bitmap.width;
    const originalHeight = image.bitmap.height;

    // Calculate the aspect ratio
    const aspectRatio = originalWidth / originalHeight;

    // Determine the new dimensions based on the desired maximum width and height
    let newWidth = originalWidth;
    let newHeight = originalHeight;

    if (originalWidth > maxWidth) {
      newWidth = maxWidth;
      newHeight = maxWidth / aspectRatio;
    }

    if (newHeight > maxHeight) {
      newHeight = maxHeight;
      newWidth = maxHeight * aspectRatio;
    }

    image.resize(newWidth, newHeight);
    image.quality(100);
    const newBuffer = await image.getBufferAsync(Jimp.MIME_PNG);
    await uploadImage(newBuffer, accountId, imageName);

    return { imageName, docUrls }; // Return the result
  } catch (error) {
    console.error("Error resizing and converting image:", error);
    return Promise.reject(error); // Reject the Promise with the error
  }
}

function imageResizeCropUpload(
  accountId: any,
  imageBuffer: any,
  imageNames: any,
  docUrls: any,
  meta: any
): Promise<void> {
  return new Promise((resolve, reject) => {
    const worker = new Worker(__filename, {
      workerData: {
        accountId,
        imageBuffer,
        imageNames,
        docUrls,
        meta
      }
    });

    worker.on("message", (result:any) => {
      resolve(result); // Resolve the Promise with the result
    });

    worker.on("error", (e:any) => {
      reject(e);
    });

    worker.on("exit", (code:any) => {
      if (code !== 0) reject(new Error(`Worker stopped with exit code ${code}`));
    });
  });
}

export default imageResizeCropUpload

SomeOtherfile.ts

import imageResizeCropUpload from './test1'
uploadPromises.push(
            imageResizeCropUpload(accountId, buffers[0], imageNames, docUrls, {
                imageIndex: 0,
                imageType: "heatmap"
            })
);

Now what is happening I don't know, but all I am getting is "Worker stopped with exit code 1" with an error as process.send() is not a function. I looked online but couldn't find anything. I am using worker threads first time. What can I try next?

Kurt Garcia · Accepted Answer · 2024-05-06 17:26:01Z

0

process.send() is a function that's used in Node.js processes that were created using child_process.fork(). This function allows child processes to communicate back to their parent process. In your scenario, you're encountering an error because you're using worker_threads, rather than child_process. The worker threads module doesn't have the process.send() function because worker threads communicate with their main thread through a different mechanism, specifically using parentPort.PostMessage()

https://nodejs.org/api/worker_threads.html

https://nodejs.org/api/child_process.html

The call to process.send() could be in Jimp or imageStorage, if that's the case, you may need to change to using child process.

answered May 6, 2024 at 17:26

Kurt Garcia

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