Unfortunately, not all Perl modules are robust enough to survive reload. For them this is an unusual situation. PerlFreshRestart does not much more than:

while (my($k,$v) = each %INC) {
    delete $INC{$k};
    require $k;
}

Besides that, it flushes the Apache::Registry cache and empties any dynamic stacked handlers (e.g., PerlChildInitHandler).

Lots of segfaults and other problems have been reported by users who turned on PerlFreshRestart. Most of them go away when it is turned off. It doesn't mean that you shouldn't use PerlFreshRestart, if it works for you. Just beware of the dragons.

Note that if you have a mod_perl-enabled Apache built as a DSO and you restart it, the whole Perl interpreter is completely torn down (via perl_destruct( )) and restarted. The value of PerlFreshRestart is irrelevent at this point.