[Fontconfig] libfontconfig.so.1.8.0's performance is not good on Ubuntu (version 2.11.0)

[Behdad Esfahbod]

Hi,

This is a known issue in Chrome:

  https://code.google.com/p/chromium/issues/detail?id=266214#c15

We tried fixing it a while back, but that broke some other stuff.  No one is
currently working on it.  I'll see if I can give it another push.

behdad

On 14-05-23 05:37 AM, Guangmu Zhu wrote:
> Hi,
> 
> It confused me very often when I was using Chrome that libfontconfig.so
> occupied too much CPU resources only when Chrome was loading a page with
> Chinese fonts such as SimSun and Microsoft YaHei. It haven't happened
> with English fonts. Actually, the .so was always the top or second in
> `perf top`.
> I have read some source codes and downloaded the debug pkg. In .so's
> DSO, a function not in symbol table usually took 90+% resources. The
> address was located between 0x1e190-0x1e360. According to debug pkg's
> symbol table and disassembled codes with objdump, all of these are a
> series of FcStrCaseWalker* functions and Ucs-Utf transcoding functions.
> And the function FcStrCaseWalkerNext's address(0x1e190) would appear
> usually.
> I read some source codes about FcStrCaseWalkerNext and its caller, but
> they seem harmless. And I tried some sample programs and a program I
> wrote, all worked very well. I guess, perhaps the function was called
> very often when using FcConfig*, FcPattern*, FcFontSet* to GetObject or
> GetString.
> On my computer(Thinkpad X240s i7-4500u), the problem could make devices'
> temperatures rise rapidly from 113 ℉ to 149 ℉ and cool down slowly for
> the .so would occupy much CPU resources always. Maybe someone could tell
> me how to deal with it?
> 
> Thanks in advance.
> 
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-- 
behdad
http://behdad.org/