Asynchronous frameworks allow developers to build stateful protocol and Internet of Things applications without threading and forking. Python, Ruby, and Node.js have had asynchronous frameworks for over ten years. PHP is now starting to catch up with Icicle.io. Learn the basic concepts of event-based programming and how the event loop allows a single thread to process all the requests for an application.

1. A S Y N C H R O N O U S
P R O G R A M M I N G I N P H P
Z E N D C O N 2 0 1 6

2. W E L C O M E T O L A S V E G A S !

3. W H O A M I ?

4. W H Y A S Y N C H R O N O U S ?

5. H I G H T R A F F I C

6. R E A C T I V E A P P L I C AT I O N S

7. I N T E R N E T O F T H I N G S

8. S TAT E F U L P R O T O C O L S E R V E R S
• WebSocket
• MQTT
• AMQP
• IRC
• XMPP
• Telnet
• SSH
• RADIUS
• LDAP
• FTP

9. H T T P / 2

10. H O W D O Y O U D O A S Y N C ?

11. S Y S T E M L E V E L A S Y N C
• German
• Apache Spark
• AWS Lambda
• Stomp
• ZeroMQ
• AMQP
J O B S E R V E R S Q U E U I N G

12. C O D E L E V E L A S Y N C
• Forking and
Threading
• Asynchronous I/O
• Fork/Join
• Event Loop
S T R AT E G I E S M E T H O D O L O G I E S

13. F O R K I N G A N D T H R E A D I N G
• Available in PHP core since PHP 4.1
• Requires the use of shared memory
• Requires code to be written for management of
forks/threads
• Creates separate copies of code for each thread/
fork

14. F O R K I N G / T H R E A D I N G L I B R A R I E S
• PCNTL/POSIX — Forking and process management
• pthreads — Thread management
• Semaphore — Semaphore (locks) and shared memory
• Shared Memory — Shared memory
• Sync — Cross platform semaphore and shared
memory

15. A S Y N C H R O N O U S I / O
• Frees up the current process while I/O is
performed
• Executes code based on I/O events
• No copying of code for separate process

16. R E A L W O R L D P R O F I L E D ATA
C AT E G O RY S E G M E N T % T I M E
AV G C A L L S
( P E R T X N )
AV G
T I M E ( M S )
D ATA B A S E M Y S Q L A P P S S E L E C T 7 2 . 6 2 . 0 3 4 . 8
F U N C T I O N
A P I . H A N D L E R S . A P P S : A P P H A N
D L E R . R E N D E R _ R E S O U R C E
1 2 . 6 1 . 0 6 . 0 4
D ATA B A S E M Y S Q L A P P U S E R M A P S E L E C T 8 . 7 3 . 9 7 4 . 1 6
F U N C T I O N
P Y R A M I D . R O U T E R : R O U T E R . _ _
C A L L _ _
3 . 3 1 . 0 1 . 5 9
M Y S Q L O R G A N I Z AT I O N S
S E L E C T
2 . 2 0 . 7 1 . 5 2

17. A S Y N C H R O N O U S I / O L I B R A R I E S
• Streams via stream_select and socket_select
• eio — libeio
• ev — libev
• libevent — libevent
• event — libevent

18. F O R K / T H R E A D V S A S Y N C I / O
• Compute heavy
• Process isolation
• Non-Async library
• I/O processes
• Process/memory
optimization
F O R K / T H R E A D A S Y N C / I O

19. F O R K / J O I N PA R A L L E L I S M
S TA RT
P R O C E S S 1
P R O C E S S 2
P R O C E S S 3
E N DF O R K J O I N

20. F O R K / J O I N E X A M P L E
// JOIN
curl_multi_remove_handle($mh, $ch1);
curl_multi_remove_handle($mh, $ch2);
curl_multi_close($mh);
$resp = array(curl_multi_getcontent($ch1),
curl_multi_getcontent($ch2));
// FORK
$active = null;
// Initiate the calls and check for completion
do {
$mrc = curl_multi_exec($mh, $active);
} while ($mrc == CURLM_CALL_MULTI_PERFORM);
while ($active && $mrc == CURLM_OK) {
if (curl_multi_select($mh) != -1) {
do {
$mrc = curl_multi_exec($mh, $active);
} while ($mrc == CURLM_CALL_MULTI_PERFORM);
}
}
<?php
// Create both cURL resources and add to cURL Multi
$ch1 = curl_init('http://www.timeapi.org/utc/now');
$ch2 = curl_init('http://www.timeapi.org/utc/now');
$mh = curl_multi_init();
curl_multi_add_handle($mh,$ch1);
curl_multi_add_handle($mh,$ch2);

21. E V E N T L O O P PA R A L L E L I S M
P R O C E S S
Q U E U E
I T E M
Q U E U E
I T E M
I N
Q U E U E ?
X
Yes
No
A S Y N C
P R O C E S S
A S Y N C
P R O C E S S
A S Y N C
P R O C E S S
A S Y N C
P R O C E S S

22. E V E N T L O O P E X A M P L E
<?php
# Build objects to handle asynchronous interaction
$loop = ReactEventLoopFactory::create();
$dnsFactory = new ReactDnsResolverFactory();
$dns = $dnsFactory->createCached('8.8.8.8', $loop);
$factory = new ReactHttpClientFactory();
$client = $factory->create($loop, $dns);
$resp = array();
# Create callback for handling response
$responseHandler = function ($response) use ($resp) {
$response->on( 'data', function ($data) use ($resp) {
$resp[] = $data;
});
};
# Queue up requests to send
$request = $client->request('GET', 'http://www.timeapi.org/utc/now');
$request->on('response', $responseHandler);
$request->end();
$request = $client->request('GET', 'http://www.timeapi.org/utc/now');
$request->on('response', $responseHandler);
$request->end();
# Run the loop
$loop->run();

23. F O R K / J O I N V S E V E N T L O O P
• Enhancing existing
traditional
synchronous apps
• Hack/HHVM
• Non-HTTP apps
• Full async apps
• High volume apps
F O R K J O I N E V E N T L O O P

24. C A L L B A C K S V S . G E N E R AT O R S

25. C A L L B A C K S V S . G E N E R AT O R S
class MyRequestHandler implements RequestHandler {
public function onRequest(Request $request, Socket $socket)
{
$response = new BasicResponse(Response::OK, [
'Content-Type' => 'text/plain',
]);
yield from $response->getBody()->end('Hello, world!');
return $response;
}
public function onError(int $code, Socket $socket)
{
return new BasicResponse($code);
}
}
$server = new Server(new MyRequestHandler());
$server->listen(8080);
Looprun();
$loop = ReactEventLoopFactory::create();
$socket = new ReactSocketServer($loop);
$http = new ReactHttpServer($socket);
$http->on('request', function ($request, $response) {
$response->writeHead(200, [‘Content-Type' => ‘text/plain']);
$response->end("Hello World!n");
});
$socket->listen(8080);
$loop->run();
Callback Generators

26. W H AT L I E S A H E A D ?

27. R E S O U R C E S
amphp icicle.io ReactPHP
PHP Asynchronous Interoperability Group
RecoilHack/HHVM

28. Q U E S T I O N S ?

29. https://joind.in/19455
P L E A S E R A T E T H I S TA L K !

30. P H O T O C R E D I T S B Y S L I D E
1: By SteveD. (Flickr) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
3: Copyright 2016 by Adam Englander. All rights reserved.
5: By Strober (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
8: By Retro-Computing Society of Rhode Island - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/
index.php?curid=5094687
11: By Victorgrigas - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20348454
15/16: By Justin De La Ornellas from China Town, Hawaii (avex18 Uploaded by clusternote) [CC BY 2.0 (http://
creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
19: By Yoga Balaji - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=35101769
21 Left: User: (WT-shared) Jpatokal at wts wikivoyage [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/
3.0)], via Wikimedia Commons
All others are public domain