Share variables/memory between all PHP processes

Question

Is it possible to share variables and arrays between all PHP processes without duplicating them?

Using memcached, I think PHP duplicates the used memory:
$array = $memcache->get('array');
$array will contain a copy from memcached.

So my idea is, there could be a static variable that was already defined, and shared between all processes.

Answer 1

Using Shmop:

Shmop is an easy to use set of functions that allows PHP to read, write, create and delete Unix shared memory segments.

from: http://www.php.net/manual/en/intro.shmop.php

No external libraries are needed to build this extension.

The shared Memory Functions

• shmop_close — Close
• shared memory block
• shmop_delete — Delete shared memory block
• shmop_open — Create or open shared memory block
• shmop_read — Read data from shared memory block
• shmop_size — Get size of shared memory block
• shmop_write — Write data into shared memory block

Basic usage

// Create 100 byte shared memory block with system id of 0xff3
$shm_id = shmop_open(0xff3, "c", 0644, 100);
if (!$shm_id) {
    echo "Couldn't create shared memory segment\n";
}

// Get shared memory block's size
$shm_size = shmop_size($shm_id);
echo "SHM Block Size: " . $shm_size . " has been created.\n";

// Lets write a test string into shared memory
$shm_bytes_written = shmop_write($shm_id, "my shared memory block", 0);
if ($shm_bytes_written != strlen("my shared memory block")) {
    echo "Couldn't write the entire length of data\n";
}

// Now lets read the string back
$my_string = shmop_read($shm_id, 0, $shm_size);
if (!$my_string) {
    echo "Couldn't read from shared memory block\n";
}
echo "The data inside shared memory was: " . $my_string . "\n";

//Now lets delete the block and close the shared memory segment
if (!shmop_delete($shm_id)) {
    echo "Couldn't mark shared memory block for deletion.";
}
shmop_close($shm_id);