> For the complete documentation index, see [llms.txt](https://docs.viesus.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.viesus.com/reference/node.js-module/getting-started.md).

# Getting Started

{% hint style="info" %}
**Linux Only**

The VIESUS Node.js module is available on **Linux only**.
{% endhint %}

The module uses a worker thread pool pattern. The main thread dispatches enhancement jobs to a pool of workers; each worker holds one persistent `MyViesusObject` instance initialized with your GUID.

***

## The two files you need

### `worker.js`

Each worker thread initializes VIESUS once on startup and then processes jobs as they arrive:

```js
const { parentPort, workerData } = require('worker_threads');
const viesus = require('viesus');

// Initialize once — workerData is the GUID passed from the pool
const viesusObj = new viesus.MyViesusObject(workerData);

parentPort.on('message', (job) => {
  const result = viesusObj.Enhance(
    job.fromPath,   // input image — absolute path
    job.toPath,     // output image — absolute path
    job.iniPath,    // viesusini.json — absolute path
    job.resPath     // result JSON — absolute path
  );
  // result > 0: processing time in ms
  // result < 0: error code (see API Reference)
  parentPort.postMessage(result);
});
```

### `testbatch.js`

The main thread creates the pool and dispatches all images in a folder:

```js
const { StaticPool } = require('node-worker-threads-pool');
const fs = require('fs');
const path = require('path');

const guid = 'YOUR-GUID-HERE';
const nGPUs = 0; // set to number of available NVIDIA GPUs; 0 = use CPU threads

const nCPUThreads = Number(process.env.UV_THREADPOOL_SIZE);
const nWorkers = nGPUs > 0 ? nGPUs : nCPUThreads;

console.log(`Workers: ${nWorkers}, GUID: ${guid}`);

const pool = new StaticPool({
  size: nWorkers,
  task: './worker.js',
  workerData: guid
});

async function enhance(fromPath, toPath, iniPath, resPath) {
  const result = await pool.exec({ fromPath, toPath, iniPath, resPath });
  console.log(result > 0 ? `OK ${result}ms: ${fromPath}` : `ERR ${result}: ${fromPath}`);
}

const imageFolder = './in';
const outputFolder = './out';
const iniPath = path.resolve('./viesusini.json');

fs.readdir(imageFolder, (err, files) => {
  if (err) process.exit(1);
  files.forEach((file) => {
    const fromPath = path.resolve(imageFolder, file);
    const toPath = path.resolve(outputFolder, file.replace(/(\.[^.]*)?$/, '_viesus.jpg'));
    const resPath = path.resolve(outputFolder, file.replace(/(\.[^.]*)?$/, '_res.json'));
    fs.stat(fromPath, (e, stat) => {
      if (!e && stat.isFile()) enhance(fromPath, toPath, iniPath, resPath);
    });
  });
});
```

***

## Running the batch

```bash
mkdir in out

# Copy test images to ./in/

export UV_THREADPOOL_SIZE=16
node testbatch.js
```

Each line of output is either `OK <ms>: <path>` (success) or `ERR <code>: <path>` (failure).

***

## Scaling to multiple GPUs

To use GPU acceleration, set `nGPUs` to the number of available NVIDIA GPUs. The pool is then limited to that count — one worker per GPU:

```js
const nGPUs = 2; // use 2 GPUs
```

One worker per GPU avoids VRAM contention. Running more workers than GPUs does not improve throughput and may cause OOM errors on the GPU.

***

## Express server integration example

This pattern integrates the pool into an Express upload endpoint:

```js
const express = require('express');
const multer = require('multer');
const { StaticPool } = require('node-worker-threads-pool');
const path = require('path');
const fs = require('fs');

const app = express();
const upload = multer({ dest: '/tmp/uploads/' });

const pool = new StaticPool({
  size: Number(process.env.UV_THREADPOOL_SIZE) || 4,
  task: './worker.js',
  workerData: process.env.VIESUS_GUID
});

app.post('/enhance', upload.single('image'), async (req, res) => {
  const fromPath = req.file.path;
  const toPath = fromPath + '_enhanced.jpg';
  const iniPath = path.resolve('./viesusini.json');
  const resPath = fromPath + '_result.json';

  try {
    const ms = await pool.exec({ fromPath, toPath, iniPath, resPath });
    if (ms < 0) return res.status(500).json({ error: ms });
    res.sendFile(toPath, () => {
      fs.unlink(fromPath, () => {});
      fs.unlink(toPath, () => {});
      fs.unlink(resPath, () => {});
    });
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

app.listen(3000);
```

Pass the GUID as an environment variable — don't hardcode it:

```bash
VIESUS_GUID="your-guid" UV_THREADPOOL_SIZE=8 node server.js
```


---

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