Slow processing with composite SVG which contains <text>

Hi,

I’m trying to add a text to my picture by using composite API and an SVG wich contains a <text> element. When I remove <text>, or try with a simple SVG, the process only takes a few ms (< 10ms) for one picture. As soon as I add a <text> element, it takes many seconds (> 7s) to process. Below a simple example with a measurment of execution time.

const sharp = require('sharp')

;(async () => {
  const overlay = `<svg width="200" height="200">
    <text x="50%" y="50%" font-family="sans-serif" dominant-baseline="middle" font-size="30" text-anchor="middle">Lorem ipsum</text>
    </svg>`

  console.time('createimage')
  await sharp(
    {
      create: {
        width: 200,
        height: 200,
        channels: 4,
        background: { r: 216, g: 216, b: 216 }
      }
    })
    .composite([{
      input: Buffer.from(overlay),
      gravity: 'center'
    }])
    .png()
    .toFile('test.png')

  console.timeEnd('createimage')
})()

With result:

createimage: 7.377s

Informations:

  Sharp : sharp@0.29.3
  System:
    OS: macOS Mojave 10.14.6
    CPU: (12) x64 Intel(R) Core(TM) i7-8700B CPU @ 3.20GHz
    Memory: 155.33 MB / 16.00 GB
    Shell: 5.3 - /bin/zsh
  Binaries:
    Node: 14.18.1 - ~/.nvm/versions/node/v14.18.1/bin/node
    npm: 6.14.15 - ~/.nvm/versions/node/v14.18.1/bin/npm

Interesting point: I’ve tried the same code on a colleague’s mac computer with M1 chip and it took only ~70ms to process (and ~5ms without <text> element).

I’m not sure it’s directly related to this lib, I saw a few issues with SVG but none wich implies <text> in the process with the composite API.

[lovell]

Closing as there’s probably nothing we can do in sharp for this. fontconfig provides the fc-cache tool to build a cache of fonts so it doesn’t have to “discover” them each time, which might help.

[lovell]

Thanks for the update, this does sound like font discovery is the problem.

I hadn’t realised valgrind is unavailable for macOS via homebrew, sorry. You might be able to use kcachegrind, which appears to be available via MacPorts - https://github.com/macports/macports-ports/tree/master/kde/kcachegrind4