Millions of calls to: "mmdc -i xx.md -o xx.pdf"

[rccclr]

Currently on windows, I need to convert millions of "mermaid" files to "pdf" and it is a slow process. Some alternative?

[aloisklink]

Currently on windows, I need to convert millions of "mermaid" files to "pdf" and it is a slow process. Some alternative?

The slow part about mermaid-cli is that every time you run it, it creates a new puppeteer browser. If you just create this browser once, it will greatly speed up your process.

I'd recommend writing your own script in Node.JS using the mermaid-cli package!

import { readFile } from 'node:fs/promises';
import { renderMermaid } from "@mermaid-js/mermaid-cli";
import puppeteer from 'puppeteer';
import pLimit from 'p-limit';

// depending on how much RAM/CPU you have, you can increase this number to get faster performance
const limit = pLimit(4);

const inputFiles = []; // your input files (can use https://www.npmjs.com/package/glob to find these)

const browser = await puppeteer.launch();
try {
  await inputFiles.map((inputFile) => limit(() => {
    console.log(`Working on file ${inputFile}`);
    const definition = await readFile(inputFile, {encoding: "utf8"});
    const { data } = await renderMermaid(browser, definition, "pdf", {});
    const outputFile = inputFile + ".pdf";
    console.log(`Writing file ${inputFile} to ${outputFile}`);
    await fs.promises.writeFile(output, data);
  }));
} finally {
  await browser.close();
}

[rccclr]

Many thanks!!!

[aloisklink]

No worries :) I have a package called remark-mermaid-dataurl that converts thousands of mermaid diagrams into SVGs in markdown diagrams, so I basically did the same thing!

By the way, please feel free to press the Mark as answer button on my comment once you confirm that it's working!

It might make sense to officially add this feature to the @mermaid-js/mermaid-cli project! But considering how hard it would be to handle the list of input files/output files/number of cores/jobs, maybe it's easier to just leave it for users to adapt the script above.