Async

Async runs PHP callables concurrently in child processes via proc_open. No pcntl, no extensions — it works on Windows, shared hosting and PHP 7.4, which makes it a fit for legacy environments where other async solutions can't run.

Basic usage

$result = await(async(static function (): int {
    usleep(100000);
    return 42;
}));

Combinators

use Maybe\Async\Async;

// Run everything, wait for all results (preserves keys)
$results = Async::all([
    'users' => async(fn () => fetchUsers()),
    'orders' => async(fn () => fetchOrders()),
]);

// First one to finish wins
$fastest = Async::race([$a, $b, $c]);

// At most $limit processes at a time
$results = Async::pool($tasks, 4);

Futures

$future = async(static fn (): int => heavyComputation(), [], ['timeout' => 2.5]);

$future
    ->then(fn ($value) => log_info("done: $value"))
    ->catch(fn ($error) => log_error($error))
    ->finally(fn () => cleanup());

$value = $future->resolve();   // blocks until done (or timeout)
$future->pending();            // non-blocking check
$future->cancel();             // kill the child process

Limitations

Because tasks run in separate processes:

• No shared memory — tasks receive serialized arguments and return serialized results.
• Non-serializable resources (DB connections, file handles) must be recreated inside the task.
• Spawn overhead — each task pays the cost of starting a PHP process; batch small units of work.

Read the Async Safety Guide before using Async in production.