in reply to Re^5: yet another thread question: is Symbol::gensym threadsafe? (history)
in thread yet another thread question: is Symbol::gensym threadsafe?

So, even though the name is deleted from the symbol table, it can still be recovered from somewhere?

Yes.

>perl -le "my $g = \do{ local *GLORB; *GLORB }; print $g; print *$g" GLOB(0x225f08) *main::GLORB

But that's not a problem, or at least not a new one, because the globs created by auto-vivification of lexicals are not uniquely named either. Your hypothicical "someone" doesn't support lexical file handles, so I wouldn't worry about his inability to support threading.