Maybe you should take a look at IPC::ShareLite

From the README:

  IPC::ShareLite provides a simple interface to shared memory, allowin
+g
  data to be efficiently communicated between processes.  Your operati
+ng
  system must support SysV IPC (shared memory and semaphores) in order
+ to
  use this module.
[download]

I assume you have SysV IPC, since you also have Unix domain sockets.

Another candidate might be Mmap:

README:

The Mmap module lets you use mmap to map in a file as a perl variable
rather than reading the file into dynamically allocated memory. It
depends on your operating system supporting UNIX or POSIX.1b mmap, of
course.
[download]

-- 
Joost       downtime n. The period during which a system
            is error-free and immune from user input.
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