[Bug 51367] Major dwrite:analyzer, dwrite:layout and dwrite:font slowdown when adding fonts

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=51367

--- Comment #4 from Nikolay Sivov <bunglehead at gmail.com> ---
(In reply to François Gouget from comment #0)
> Created attachment 70223 [details]
> Command and fonts for Debian's locales
> 
> Adding fonts causes major slowdowns in dwrite:analyzer, dwrite:layout and
> dwrite:font when running in Wine. On my test VM I get the following run
> times:



> 
> Is that because of lots of global locking?

There is a global lock, yes. I don't know how much it contributes.

> Or because each test adds/removes fonts forcing all the other threads to do
> many rescans?
> Are all fonts reloaded and analyzed despite most fonts not having changed?
> 
> 

Pretty much. There is no caching of any kind, everything listed in Fonts
registry key is loaded once you create a shared font factory. Many tests
intentionally don't share a factory to keep them independent. 

The main reason test times depend on a number of fonts is that some tests
iterate over whole collection, and test usually first of each family. I'd like
to keep that because it gives a best coverage, and I was able to fix multiple
problems that are hard to spot otherwise, mostly for global font properties
related to table data interpretation.

Productive thing to do is to analyze which parts are particularly slow. On
Windows I believe font file access is optimized by caching things at single
system process level, dedicated for such font data caching. That goes back to
WPF 3 I believe. It's possible we could get these times improved without such
complications. For example when building default collection it currently scans
a list of files for every new font, so that loop runs n*n times for n files
(it's probably avoidable by collecting unique font file paths first by making
enumerator a bit smarter). I don't know if that will have a noticeable impact
though. Another thing is to use the global lock less, but keeping data closer
to dwrite instances, rather than freetype instances.

For now, the easiest way is to limit a number of fonts so it does not timeout.

-- 
Do not reply to this email, post in Bugzilla using the
above URL to reply.
You are receiving this mail because:
You are watching all bug changes.