I tried to build mod_perl with Perl configured without ithreads but with enabled multiplicity option (useithreads=undef, usemultiplicity=define) (-Duseshrplib enabled) And I found that it's impossible to use multiplicity w/o threads in mod_perl:
.....*warnings*..... /mod_perl.src.dir/mod_perl.c:732: error: 'my_perl' undeclared (first use in this function) ....*errors & warnings*...... Tell me please, is it reasonable behavior or it's mod_perl's bug?
