Re: [NTG-context] XeConTeXt bug report I: strange benchmark

On Tue, May 12, 2009 at 10:50 PM, Hans Hagen wrote:

Yue Wang wrote:

...

On Tue, May 12, 2009 at 8:54 PM, Hans Hagen wrote:

...

Yue Wang wrote:

...

moreover, can you tell me why pdftex load these fonts so fast? (also 6 families * 3 sizes)

i don't know; as the same code is used so it must be xetex itself then

Then let me tell you why: ConTeXt tries to load lmmono10-regular at least 6 times, failed after two testing, then succeed in the end. However, try to testing whether a loaded font is \nullfont or not is quite slow in XeTeX (Jonathan already mentioned that in \testFontIsAvailable). we should definately avoid that. But why pdftex is so fast? because it does not involve font testing.

So why XeTeX is spending 6 seconds aimlessly? since ConTeXt asked it to search for a non-existed font.

well, even locating a font 6 times should be no big deal

loading 6 fonts, each fonts will be scanned for 3 times. so there are 18 searching. 12 of them are fc searches, and these are quite slow.

btw, you can try to change the following into

\def\defaultfontfile{file:lmmono10-regular}

After changing like this, XeTeX runs like a blink. (It wasted 6 seconds for each compile. now it won't)

but even then ... if that one is used then there is something else going on so best find out what happens ... in context we can have 4 extra math families and in most cases only two are used (MathAlpha and MathBeta) while (just in onder to catch errors) MathGamma etc then automatically will trigger the default font to be used (other approached would demand more definitions at the user end and/or a more low level implementation); the only optimization i can imagine is more clever sharing of the default font but as in other cases one expects the default to be properly scaled it not that simple; after all, users also expect proper error recovery (and in many cases missing some specific fonts is no real problem until it's used); so, you can hardly blame context for the fact that xetex has a certain logix on locating fonts that happens to be not that good a match for context

The fact that xetex uses this mixture of "" en [] does not help either as context uses [] itself so parsing is somewhat complicated (the file/name prefix was introduced to circumvent this problem);

Hans

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