ComponentsThreadPool::close()

ThreadPool::close() ​

(PHP 8.6+, True Async 1.0)

php
public ThreadPool::close(): void

Initiates a graceful shutdown of the pool. After close() is called:

  • Any subsequent submit() call immediately throws Async\ThreadPoolException.
  • Tasks already in the queue continue and complete normally.
  • Tasks currently executing in worker threads complete normally.
  • The method blocks the calling coroutine until all in-progress tasks have finished and all workers have stopped.

For an immediate, hard shutdown that discards queued tasks, use cancel() instead.

Return Value ​

void

Examples ​

Example #1 Graceful shutdown after all tasks are submitted ​

php
<?php

use Async\ThreadPool;
use function Async\spawn;
use function Async\await;

spawn(function() {
    $pool = new ThreadPool(workers: 2);

    $future = $pool->submit(function() {
        return 'finished';
    });

    $pool->close(); // waits for the task above to complete

    echo await($future), "\n"; // finished

    $pool->close();
});

Example #2 Submit after close throws an exception ​

php
<?php

use Async\ThreadPool;
use Async\ThreadPoolException;
use function Async\spawn;

spawn(function() {
    $pool = new ThreadPool(workers: 2);
    $pool->close();

    try {
        $pool->submit(fn() => 'too late');
    } catch (ThreadPoolException $e) {
        echo "Error: ", $e->getMessage(), "\n";
        // Error: Cannot submit task: thread pool is closed
    }
});

See Also ​