sure but Data::Lock is not core.

If a real @array should be locked and unlocked in a core way, I would use Tie::Array to tie or untie it to a class "lock_array" with restricted modifying methods.

IMHO anything faster is either not core or needs another interface for wrappers like inline functions resp. constants.

UPDATE:

Well ...

Most I wrote was already elaborated in much detail in Readonly.pm.

And an additional XS modul is also mentioned...