Re: LANG setting and X server hang

[email protected] said:
> I am seeing the X server hang completely when trying to open this
> email message:
[...snip...]

> The interesting thing is that this happens with LANG=en_US.UTF-8 but
> not when I unset LANG.

I've a guess about what's happening, because it sounds like something
that I'm trying to troubleshoot even as I write this.

It appears that Tk on Un*x (either 8.4, or 8.5 built without --enable-xft)
has some sort of grievous performance bug in font substitution.
The message in question has an enclosure in gb2312 encoding, so likely
contains Simplified Han characters.  And I'm guessing that your system
totally lacks a Simplified Han font.

When Tk attempts to display a character that isn't in the specified font,
it tries every font in the system to see if the character is available.
Moreover, it does something that in some circumstances overloads the X
server - I've seen it take several minutes of CPU time to display a 
string of 256 unknown characters.

I suspect further that the LANG difference is that it makes the X
libraries search a broader set of fonts (including the huge ones
with iso10646 encoding) - but I've no proof of this.

I've not seen nearly as bad performance issues with rendering unknown
characters on Windows, or in a Tk8.5 build with --enable-xft.

If I'm right, then installing a broader set of CJK fonts, including
Simplified Han, might help.  
--
73 de ke9tv/2, Kevin KENNY   GE Corporate Research & Development
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