parallel/examples/shared-memory-parcel.php

#!/usr/bin/env php
<?php
require \dirname(__DIR__).'/vendor/autoload.php';

use Amp\ByteStream;
use Amp\Delayed;
use Amp\Loop;
use Amp\Parallel\Context\Process;
use Amp\Parallel\Sync\SharedMemoryParcel;

Loop::run(function () {
    // Create a parcel that then can be accessed in any number of child processes.
    $parcel = SharedMemoryParcel::create($id = \bin2hex(\random_bytes(10)), 1);

    $context = yield Process::run([
        __DIR__ . "/parcel-process.php",
        $id, // Send parcel ID to child process as command argument.
    ]);

    \assert($context instanceof Process);

    // Pipe any data written to the STDOUT in the child process to STDOUT of this process.
    Amp\Promise\rethrow(ByteStream\pipe($context->getStdout(), ByteStream\getStdout()));

    yield new Delayed(100); // Give the process time to start and access the parcel.

    yield $parcel->synchronized(function (int $value) {
        return $value + 1;
    });

    yield $context->join(); // Wait for child process to finish.

    \printf("Final value of parcel: %d\n", yield $parcel->unwrap());
});