Editing Portal:HPC - High Performance Computing (section)

=== Shared memory in Perl ===

Shared memory is another important parallel-programming idea. In a shared-memory model, multiple processes or threads can access a common memory region rather than sending every piece of data through files, sockets, or pipes.

Perl has general shared-memory modules. `IPC::Shareable` allows a Perl variable to be tied to shared memory, making it possible to share the contents of that variable with other Perl processes and scripts. Its documentation says scalars, arrays, hashes, and even objects can be tied.<ref>MetaCPAN, “IPC::Shareable,” https://metacpan.org/pod/IPC%3A%3AShareable, accessed July 3, 2026.</ref>

`IPC::ShareLite` provides a lightweight interface to shared memory and uses SysV IPC shared memory and semaphores where supported by the operating system.<ref>MetaCPAN, “IPC::ShareLite,” https://metacpan.org/pod/IPC%3A%3AShareLite, accessed July 3, 2026.</ref>

`IPC::SharedMem` provides a SysV shared-memory IPC object class, including attach, detach, read, and write operations around shared-memory segments.<ref>MetaCPAN, “IPC::SharedMem,” https://metacpan.org/pod/IPC%3A%3ASharedMem, accessed July 3, 2026.</ref>

These modules are useful for local interprocess communication, caching, coordination, and single-node shared state. They are not the same as OpenMP, MPI, or OpenSHMEM. They do not automatically turn a Perl program into a scalable scientific application. But they show that Perl can work with operating-system shared-memory mechanisms when needed.