Every now and again perl will become broken or corrupt either because of something we’ve done or, like most things, out of nowhere with now warning. Run the following:
cd /usr/local/src wget http://layer1.cpanel.net/perl588installer.tar.gz tar -vzxf perl588installer.tar.gz cd perl588installer ./install
[/usr/local/src/perl588installer]# grep 'my $flags' install my $flags = '-Duseithreads'; [/usr/local/src/perl588installer]# and [/usr/local/src/perl588installer]# perl -V | egrep thread ... usethreads=define use5005threads=undef useithreads=define usemultiplicity=define ...
To answer your question regarding the difference between -Dusethreads and -Duseithreads—there is no -Duseithreads. According to the INSTALL doc:
“By default, Configure selects ithreads if -Dusethreads is specified”.
As for the next question, you didn’t compile it with threads because you used -Duseithreads when you should have used -Dusethreads.