Output pages in parallel

[hmenke]

dvisvgm is pretty slow compared to regular TeX page output. Since it is written in C++11 it could make use of cross-platform multithreading. Would it be possible to output pages in parallel?

[mgieseki]

Unfortunately, DVI is a linear format, i.e. several commands that describe or annotate the content of a page may affect preceding and following pages as well. Thus, it's necessary to process the pages sequentially or to scan the entire file in advance. dvisvgm does the latter. I don't see much room for speed optimizations here.
In order to parallelize the actual conversion of the DVI pages, a huge amount of the current code had to be redesigned. I guess that's too big a task for a single developer. At least at the moment I can't estimate when I would have enough time to work on it.

[hmenke]

I just looked at this again today and it seems that these loops need to be parallelized:

dvisvgm/src/ImageToSVG.cpp

Lines 139 to 143 in c2a8942

	for (const auto &range : ranges) {
	convert(range.first, range.second, pageinfo);
	if (pageinfo)
	pageCount += pageinfo->first;
	}

dvisvgm/src/DVIToSVG.cpp

Lines 178 to 179 in c2a8942

	for (const auto &range : ranges)
	convert(range.first, range.second, hashFunc.get());