Frozen

An immutable container that survives a fork.

Perl's preload-then-fork idiom does not do what it appears to. Data loaded
before a fork is shared with every worker by copy-on-write, but the first
READ of an SV writes to its reference count, the page is copied, and the
sharing is gone. Under traffic it lasts about as long as it takes to serve
the first request.

Measured on Linux with four workers reading 20,000 random keys out of a
preloaded nested hash: 47 MiB of previously shared pages became private. An
exists check that never fetches a value still dirtied 18 MiB, because the
cost is walking the structure rather than copying the string at the end of
it.

CPython hit the same wall and answered it in 3.7 with gc.freeze(). Perl has
no answer. Frozen is one: an immutable, position-independent block of bytes
holding nested data, addressed by offset, read without touching a reference
count.

This release is the build plumbing and the ABI resolution mechanism. The
format, the reader and the doors onto it land in the releases that follow.

Requires a C compiler and perl 5.10 or later. No runtime prerequisites.


INSTALLATION

To install this module, run the following commands:

	perl Makefile.PL
	make
	make test
	make install

SUPPORT AND DOCUMENTATION

After installing, you can find documentation for this module with the
perldoc command.

    perldoc Frozen

You can also look for information at:

    RT, CPAN's request tracker (report bugs here)
        https://rt.cpan.org/NoAuth/Bugs.html?Dist=Frozen

    Search CPAN
        https://metacpan.org/release/Frozen


LICENSE AND COPYRIGHT

This software is Copyright (c) 2026 by LNATION <email@lnation.org>.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)