The State of Asynchronous PHP

Given at PHP Usergroup Hamburg's June 2019 Meetup: https://www.meetup.com/phpughh/events/fpnmzmyzjbpb/

The code examples can be found at https://github.com/sebastianheuer/phpughh-june-2019

Event-driven architectures heavily increased the need for developing software in an asynchronous fashion. Languages like Go make running multiple parallel tasks look easy, but what if you want to stick to PHP? Let's have a look at different approaches of doing asynchronous work in PHP and what they could be used for.

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1. THE STATE OF ASYNCHRONOUS PHP
2. REACTPHP
3. EVENT-DRIVEN PROGRAMMING WITH REACTPHP
4. <?php require __DIR__ . '/vendor/autoload.php'; $loop = \React\EventLoop\Factory::create(); $read = new \React\Stream\ReadableResourceStream(fopen('php://stdin', 'r+'), $loop); $write = new \React\Stream\WritableResourceStream(fopen('php://stdout', 'w+'), $loop); $superFabulous = new \Fab\SuperFab(); $write->on('close', function() { echo Kitten::get() . ' says bye!' . PHP_EOL; }); $read->on('data', function(string $input) use ($read, $write, $superFabulous) { $input = trim($input); if ($input === 'bye') { $read->close(); $write->close(); } $write->write( $superFabulous->paint(sprintf('%s says: "%s"', Kitten::get(), $input) . PHP_EOL) ); }); $loop->run();
5. <?php require __DIR__ . '/vendor/autoload.php'; $loop = \React\EventLoop\Factory::create(); $read = new \React\Stream\ReadableResourceStream(fopen('php://stdin', 'r+'), $loop); $write = new \React\Stream\WritableResourceStream(fopen('php://stdout', 'w+'), $loop); $superFabulous = new \Fab\SuperFab(); $write->on('close', function() { echo Kitten::get() . ' says bye!' . PHP_EOL; }); $read->on('data', function(string $input) use ($read, $write, $superFabulous) { $input = trim($input); if ($input === 'bye') { $read->close(); $write->close(); } $write->write( $superFabulous->paint(sprintf('%s says: "%s"', Kitten::get(), $input) . PHP_EOL) ); }); $loop->run();
6. FPM
7. PRAGMATIC AT SCALE QUEUE PROCESSING
8. FPM Master Process FPM Worker Processes Webserver
9. FPM Master Process FPM Worker Processes Webserver
10. FPM Master Process FPM Worker Processes Webserver
11. FPM Master Process FPM Worker Processes PHP Application
12. https://github.com/hollodotme/fast-cgi-client
13. <?php declare(strict_types=1); use hollodotme\FastCGI\Client; use hollodotme\FastCGI\Requests\PostRequest; use hollodotme\FastCGI\Responses\Response; class FastCgiEventListener { /** @var Event[] */ private $activeTasks = []; /** @var Client */ private $fastCgiClient; /** @var RedisEventStream */ private $stream; public function __construct(Client $fastCgiClient, RedisEventStream $stream) { $this->fastCgiClient = $fastCgiClient; $this->stream = $stream; } public function listen(): void { while (true) { if ($this->fastCgiClient->hasUnhandledResponses()) { $this->fastCgiClient->handleReadyResponses(); } if (!$event = $this->stream->getNextEvent()) { FastCgiEventListener.php
14. $this->stream = $stream; } public function listen(): void { while (true) { if ($this->fastCgiClient->hasUnhandledResponses()) { $this->fastCgiClient->handleReadyResponses(); } if (!$event = $this->stream->getNextEvent()) { usleep(15000); continue; } $request = new PostRequest( '/app/handleEvent.php', $event->getPayload() ); $request->addResponseCallbacks([$this, 'handleResponse']); $requestId = $this->fastCgiClient->sendAsyncRequest($request); $this->activeTasks[$requestId] = $event; } } public function handleResponse(Response $response): void { if ($response->getError() !== '') { echo 'F'; unset($this->activeTasks[$response->getRequestId()]); return; } echo 'S'; FastCgiEventListener.php
15. '/app/handleEvent.php', $event->getPayload() ); $request->addResponseCallbacks([$this, 'handleResponse']); $requestId = $this->fastCgiClient->sendAsyncRequest($request); $this->activeTasks[$requestId] = $event; } } public function handleResponse(Response $response): void { if ($response->getError() !== '') { echo 'F'; unset($this->activeTasks[$response->getRequestId()]); return; } echo 'S'; $this->stream->acknowledge($this->activeTasks[$response->getRequestId()]); unset($this->activeTasks[$response->getRequestId()]); } } FastCgiEventListener.php
18. class GenerateScoresCommand { private const MAX_CONCURRENT_REQUESTS = 32; /** * @var SimilarityMapWriter */ private $similarityMapWriter; /** * @var ProductListReader */ private $productListReader; /** * @var CalculationTaskList */ private $taskList; /** * @var FastCgiTaskRunner */ private $taskRunner; public function __construct( SimilarityMapWriter $similarityMapWriter, ProductListReader $productListReader, FastCgiTaskRunner $taskRunner ) { $this->similarityMapWriter = $similarityMapWriter; GenerateScoresCommand.php
19. ProductListReader $productListReader, FastCgiTaskRunner $taskRunner ) { $this->similarityMapWriter = $similarityMapWriter; $this->productListReader = $productListReader; $this->taskRunner = $taskRunner; } public function execute(StoreCode $storeCode): void { $productIdentifiers = $this->productListReader->read($storeCode); $this->taskList = new CalculationTaskList(self::MAX_CONCURRENT_REQUESTS); do { $this->taskRunner->updateTaskStatuses(); if (!$this->taskList->acceptsAnotherTask() || !$productIdentifiers->hasCurrent()) { usleep(15000); continue; } $task = new CalculationTask($productIdentifiers->getCurrent(), $storeCode); $taskId = $this->taskRunner->run($task, [$this, 'handleCompletedTask']); $this->taskList->addTask($taskId, $task); $productIdentifiers->moveToNext(); } while ($this->taskList->hasTasks()); } public function handleCompletedTask(int $taskId, $taskResult): void { GenerateScoresCommand.php
20. continue; } $task = new CalculationTask($productIdentifiers->getCurrent(), $storeCode); $taskId = $this->taskRunner->run($task, [$this, 'handleCompletedTask']); $this->taskList->addTask($taskId, $task); $productIdentifiers->moveToNext(); } while ($this->taskList->hasTasks()); } public function handleCompletedTask(int $taskId, $taskResult): void { $task = $this->taskList->getTask($taskId); $scores = @unserialize($taskResult); if ($scores === false) { throw new InvalidTaskResultException(sprintf('Could not unserialize task result %s', $taskResult)); } $this->similarityMapWriter->write($task->getStoreCode(), $task->getProduct()->getIdentifier(), $scores); $this->taskList->removeTask($taskId); } } GenerateScoresCommand.php
21. <?php use Kartenmacherei\SimilarProductsService\Backend\BackendFactory; use Kartenmacherei\SimilarProductsService\Backend\Exception\UnsupportedTaskTypeException; use Kartenmacherei\SimilarProductsService\Backend\ScoreCalculation\CalculationTask; use Kartenmacherei\SimilarProductsService\Shared\SharedFactory; require __DIR__ . '/../vendor/autoload.php'; $factory = new BackendFactory(new SharedFactory()); $task = unserialize(file_get_contents('php://input')); if (!$task instanceof CalculationTask) { throw new UnsupportedTaskTypeException(sprintf('Task Type %s is not supported.', get_class($task))); } $scores = $factory->createCalculationTaskHandler()->handle($task); echo serialize($scores->getTop(24)); calculate.php
22. PHP Application Worker FastCGI Proxy Server B Server C Server A FPM FPM Worker Worker Worker Worker Worker
23. PTHREADS
25. PARALLEL
26. REQUIRES PHP WITH ZTS
27. CalculateCommand.php <?php declare(strict_types=1); namespace ParallelPhp; class CalculateCommand { /** * @var ProgressOutput */ private $progressOutput; /** * @var \parallel\Events */ private $events; /** * @var array \parallel\Runtime[] */ private $runtimes = []; /** * @var \React\EventLoop\LoopInterface */ private $loop; public function __construct(ProgressOutput $progressOutput) { $this->progressOutput = $progressOutput;
28. CalculateCommand.php private $loop; public function __construct(ProgressOutput $progressOutput) { $this->progressOutput = $progressOutput; } public function execute(array $tasks): void { $this->progressOutput->init(count($tasks)); $this->events = new \parallel\Events(); $this->events->setTimeout(1); $this->loop = \React\EventLoop\Factory::create(); $this->catchSigintSignal(); $this->exitWhenNoRuntimesAreLeft(); $this->checkForEventsPeriodically(); $this->registerRuntimes($tasks); $this->loop->run(); $this->progressOutput->finalize(); } private function registerRuntimes(array $tasks): void { foreach ($tasks as $id => $task) { $this->events->addChannel(\parallel\Channel::make((string)$id, \parallel\Channel::Infinite));
29. CalculateCommand.php $this->registerRuntimes($tasks); $this->loop->run(); $this->progressOutput->finalize(); } private function registerRuntimes(array $tasks): void { foreach ($tasks as $id => $task) { $this->events->addChannel(\parallel\Channel::make((string)$id, \parallel\Channel::Infinite)); $runtime = new \parallel\Runtime(__DIR__ . '/../vendor/autoload.php'); $future = $runtime->run(function (int $id, string $serializedTask) { $taskHandler = new TaskHandler(); $task = unserialize($serializedTask); return $taskHandler->handle($id, $task); }, [$id, serialize($task)]); $this->events->addFuture('task'.(string)$id, $future); $this->runtimes[$id] = $runtime; unset($tasks[$id]); } } private function checkForEventsPeriodically(): void { $this->loop->addPeriodicTimer(0.001, function () use (&$timer) { try {
30. CalculateCommand.php }, [$id, serialize($task)]); $this->events->addFuture('task'.(string)$id, $future); $this->runtimes[$id] = $runtime; unset($tasks[$id]); } } private function checkForEventsPeriodically(): void { $this->loop->addPeriodicTimer(0.001, function () use (&$timer) { try { while ($event = $this->events->poll()) { $this->handleEvent($event); } } catch (\parallel\Events\Error\Timeout $exception) { return; } }); } private function handleEvent(\parallel\Events\Event $event) { if ($event->type !== \parallel\Events\Event\Type::Read) { return; } if ($event->object instanceof \parallel\Channel) { $id = (int)$event->source; if(!array_key_exists($id, $this->runtimes)) { return; }
31. CalculateCommand.php private function handleEvent(\parallel\Events\Event $event) { if ($event->type !== \parallel\Events\Event\Type::Read) { return; } if ($event->object instanceof \parallel\Channel) { $id = (int)$event->source; if(!array_key_exists($id, $this->runtimes)) { return; } try { $progress = (int)$event->object->recv(); $this->progressOutput->update($id, $progress); $this->events->addChannel($event->object); } catch (\parallel\Channel\Error\Closed $exception) { } return; } if ($event->object instanceof \parallel\Future) { $result = $event->value; /** @var TaskResult $result */ $id = $result->getId(); if (!$result->succeeded()) { $this->progressOutput->markAsFailed($id); unset($this->runtimes[$id]); return; } $this->progressOutput->markAsSucceeded($id); unset($this->runtimes[$id]); } }
32. CalculateCommand.php unset($this->runtimes[$id]); } } private function exitWhenNoRuntimesAreLeft(): void { $this->loop->addPeriodicTimer(0.05, function () use (&$timer) { if (count($this->runtimes) === 0) { $this->progressOutput->finalize(); exit; } }); } private function catchSigintSignal(): void { $this->loop->addSignal(SIGINT, function() { echo "SIGINT received \n"; foreach ($this->runtimes as $runtime) { $runtime->close(); } $this->loop->stop(); exit; }); } }
33. <?php declare(strict_types=1); namespace ParallelPhp; class TaskHandler { public function handle(int $id, Task $task): TaskResult { $channel = \parallel\Channel::open((string)$id); $cycles = random_int(1, 200); for ($i = 0; $i < $cycles; $i++) { usleep(25000); $channel->send((int)round($i / $cycles * 100)); } $channel->close(); return new TaskSucceededResult($id); } } TaskHandler.php
37. FPM
38. FPM ๏ WEB CONTEXT
39. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER
40. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER ๏ CAN BE SCALED HORIZONTALLY
41. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER ๏ CAN BE SCALED HORIZONTALLY PARALLEL
42. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER ๏ CAN BE SCALED HORIZONTALLY ๏ CLI CONTEXT PARALLEL
43. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER ๏ CAN BE SCALED HORIZONTALLY ๏ CLI CONTEXT ๏ LIMITED TO ONE MACHINE PARALLEL
44. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER ๏ CAN BE SCALED HORIZONTALLY ๏ CLI CONTEXT ๏ LIMITED TO ONE MACHINE ๏ BI-DIRECTIONAL COMMUNICATION PARALLEL
45. FPM ๏ WEB CONTEXT ๏ CONTINUOUSLY RUNNING LISTENER ๏ CAN BE SCALED HORIZONTALLY ๏ CLI CONTEXT ๏ LIMITED TO ONE MACHINE ๏ BI-DIRECTIONAL COMMUNICATION ๏ (ZTS REQUIRED) PARALLEL
46. THANK YOU!