Shared Memory

Shared memory is a powerful PHP feature that allows multiple processes to access and store data in a shared memory segment.

<?php

    // adapted from the PHP manual : https://www.php.net/manual/en/shmop.examples-basic.php
    // 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";
    }

    // 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";

?>

Documentation

See also A Guide to the PHP SHMOP Library for Shared Memory Operations.

Related : Memory