# for f in `seq 40123`; do echo " #alfa beta"; done | perl -e 'use strict; use warnings; undef $/; my $s = <STDIN>; print length $s, "\n"; $s =~ /\G (?: \s++ | \# .*+ )++ /xgc; print pos $s, "\n"; '
481476
Complex regular subexpression recursion limit (32766) exceeded at -e line 1, <STDIN> chunk 1.
196597