[tex4ht] How to control/optimize the number of times make4ht runs dvilualatex?

[Nasser M. Abbasi]

Since some of my files take long time to compile for PDF and HTML,
I've been trying to optimize the number of times needed to compile
them.

With lualatex, I now check in the log file and decided if there
is a need to run lualatex one more time or not.

For tex4ht, it seems to always run 3 times. Even for the most
simple files. Here is an example

-----------------------------
>cat report.tex
\documentclass[11pt]{book}
\begin{document}
test
\end{document}
---------------------------

Running the command (all on one line)

time make4ht -ulm default -a debug report.tex "mathjax,htm"


Shows that

htlatex: LaTeX call: dvilualatex --interaction=errorstopmode -jobname='report'

was called 3 times. Each time. Of course on a small file like this,
it does not matter, but I have files where I timed it taking over 2 hrs
for each one call to dvilualatex. This means 6 hrs in total. This
phase seems to take most of the time.

If I can reduce it to calling it 2 times, this will be big reduction in
time.

But I have no idea how make4ht decides if it needs to run 1 or 2 or 3 times
the program dvilualatex.

With lualatex, it is easy to check. I just check if the log file
contain the string `Rerun` and other variation of it.

My question is: how does make4ht decide it needs to run 3 times
each time? Is it possible to make it more optimal? How would the
user control this from outside?

Thanks
--Nasser