May the file LuaInsert.tex consist of \documentclass{minimal} \makeatletter \newcommand{\stressInsert}[1]{% \@tempcnta=0\relax% \@whilenum\the\@tempcnta<#1\do% {\advance\@tempcnta +1\relax% \expandafter\newinsert\csname TestInsert\the\@tempcnta\endcsname% \message{insert \the\@tempcnta: \the\allocationnumber^^J}% }% } \makeatother \stressInsert{70000} \begin{document} \end{document} then
lualatex LuaInsert.tex
creates LuaInsert.log, which also contains: This is LuaHBTeX, Version 1.16.0 (TeX Live 2023) (format=lualatex 2023.4.4) ... \TestInsert1=\insert199 insert 1: 199 \TestInsert2=\insert198 insert 2: 198 ... \TestInsert17=\insert183 insert 17: 183 [ *** 1st JUMP HERE *** ] \TestInsert18=\insert252 insert 18: 252 \TestInsert19=\insert251 insert 19: 251 ... \TestInsert68=\insert202 insert 68: 202 \TestInsert69=\insert201 insert 69: 201 [ *** 2nd JUMP HERE *** ] \TestInsert70=\insert65534 insert 70: 65534 \TestInsert71=\insert65533 insert 71: 65533 ... \TestInsert65350=\insert254 insert 65350: 254 \TestInsert65351=\insert253 insert 65351: 253 \TestInsert65352=\insert252 [ *** AGAIN?! ***] insert 65352: 252 \TestInsert65353=\insert251 [ *** AGAIN?! ***] insert 65353: 251 ... \TestInsert65368=\insert236 [ *** AGAIN?! ***] insert 65368: 236 \TestInsert65369=\insert235 [ *** AGAIN?! ***] insert 65369: 235 ! No room for a new \count . \ch@ck ...\else \errmessage {No room for a new #3} \fi l.12 \stressInsert{70000} ? x So, are \insert252 to \insert235 used twice?! And Lua does not even stop there because of "No room for a new insert", but because there is no room for a new \count! Otherwise more inserts would see double use? Should after \insert253 (!, not 235) the next \newinsert produce some error "No room for a new \insert"?