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Direct links to the tweets that prompted this article. Github - https://twitter.com/pcwalton/status/633411771617832961 https://twitter.com/pcwalton/status/6334

Direct links to the tweets that prompted this article. Github - https://twitter.com/pcwalton/status/633411771617832961 https://twitter.com/pcwalton/status/633411771617832961 Ars - https://twitter.com/pcwalton/status/631961638304804864 https://twitter.com/pcwalton/status/631961638304804864

haberman 11y ago
Really curious to hear more explanation of this comment from Patrick: "Printing is pretty incompatible with parallelism though." Is he saying that Servo as a parallel engine won't be able to handle printing?
- pjmlp 11y ago
  Most likely due to the way printing APIs work across OSes.
- dubcanada 11y ago
  I'm assuming what they would do is render the website using multi threading and then generate a PDF or something and print that. But basically printing APIs are not multithreaded across all OS's
- smt88 11y ago
  It's likely possible to work around that limitation. For example, Servo could render to a binary image and then send that to the printer.
  - jahewson 11y ago
    Using a raster image is a recepie for slowness, especially at common printer resolutions of 300dpi+. It also breaks "Save as PDF" from the print dialog. Far better to communicate with the print driver using GDI, PostScript, PCL, PDF, etc. using vector graphics and embedded fonts.
  - pcwalton 11y ago
    That's not the problem. We could easily run our parallel screen layout and then just use Skia (or the local system)'s PDF backend. The trouble is that this doesn't implement the printing spec. As Simon mentioned above, the problem is the various CSS rules that control pagination.
  - gsnedders 11y ago
    That's not the limitation — the limitation is the effects of pagination on layout, especially given control of where page breaks occur and restrictions on widows and orphans.
- leni536 11y ago
  What kind of parallelism is expected here? Is it about that you can't render layout to postscript or PDF well parallelized?
- SimonSapin 11y ago
  Patrick refers to parallel layout here: in a text with many paragraphs for example, the contents of each paragraph can be laid out in parallel with other paragraphs. Then you only need to sum up the heights of earlier paragraphs to find the vertical position of each. When printing though, you don’t know where to start page 10 until you’ve done the layout of earlier pages. There may still be some parallelism opportunity, but less than on screen.

haberman 11y ago

Really curious to hear more explanation of this comment from Patrick: "Printing is pretty incompatible with parallelism though." Is he saying that Servo as a parallel engine won't be able to handle printing?

pjmlp 11y ago
Most likely due to the way printing APIs work across OSes.
dubcanada 11y ago
I'm assuming what they would do is render the website using multi threading and then generate a PDF or something and print that. But basically printing APIs are not multithreaded across all OS's
smt88 11y ago
It's likely possible to work around that limitation. For example, Servo could render to a binary image and then send that to the printer.
- jahewson 11y ago
  Using a raster image is a recepie for slowness, especially at common printer resolutions of 300dpi+. It also breaks "Save as PDF" from the print dialog. Far better to communicate with the print driver using GDI, PostScript, PCL, PDF, etc. using vector graphics and embedded fonts.
- pcwalton 11y ago
  That's not the problem. We could easily run our parallel screen layout and then just use Skia (or the local system)'s PDF backend. The trouble is that this doesn't implement the printing spec. As Simon mentioned above, the problem is the various CSS rules that control pagination.
- gsnedders 11y ago
  That's not the limitation — the limitation is the effects of pagination on layout, especially given control of where page breaks occur and restrictions on widows and orphans.
leni536 11y ago
What kind of parallelism is expected here? Is it about that you can't render layout to postscript or PDF well parallelized?
SimonSapin 11y ago
Patrick refers to parallel layout here: in a text with many paragraphs for example, the contents of each paragraph can be laid out in parallel with other paragraphs. Then you only need to sum up the heights of earlier paragraphs to find the vertical position of each. When printing though, you don’t know where to start page 10 until you’ve done the layout of earlier pages. There may still be some parallelism opportunity, but less than on screen.