Run PHP Task Asynchronously

Question

I work on a somewhat large web application, and the backend is mostly in PHP. There are several places in the code where I need to complete some task, but I don\'t want to m

Answer 1

PHP is a single-threaded language, so there is no official way to start an asynchronous process with it other than using exec or popen. There is a blog post about that here. Your idea for a queue in MySQL is a good idea as well.

Your specific requirement here is for sending an email to the user. I'm curious as to why you are trying to do that asynchronously since sending an email is a pretty trivial and quick task to perform. I suppose if you are sending tons of email and your ISP is blocking you on suspicion of spamming, that might be one reason to queue, but other than that I can't think of any reason to do it this way.

Answer 2

If it just a question of providing expensive tasks, in case of php-fpm is supported, why not to use fastcgi_finish_request() function?

This function flushes all response data to the client and finishes the request. This allows for time consuming tasks to be performed without leaving the connection to the client open.

You don't really use asynchronicity in this way:

1. Make all your main code first.
2. Execute fastcgi_finish_request().
3. Make all heavy stuff.

Once again php-fpm is needed.

Answer 3

Unfortunately PHP does not have any kind of native threading capabilities. So I think in this case you have no choice but to use some kind of custom code to do what you want to do.

If you search around the net for PHP threading stuff, some people have come up with ways to simulate threads on PHP.

Answer 4

If you don't want the full blown ActiveMQ, I recommend to consider RabbitMQ. RabbitMQ is lightweight messaging that uses the AMQP standard.

I recommend to also look into php-amqplib - a popular AMQP client library to access AMQP based message brokers.

Answer 5

When you just want to execute one or several HTTP requests without having to wait for the response, there is a simple PHP solution, as well.

In the calling script:

$socketcon = fsockopen($host, 80, $errno, $errstr, 10);
if($socketcon) {   
   $socketdata = "GET $remote_house/script.php?parameters=... HTTP 1.1\r\nHost: $host\r\nConnection: Close\r\n\r\n";      
   fwrite($socketcon, $socketdata); 
   fclose($socketcon);
}
// repeat this with different parameters as often as you like

On the called script.php, you can invoke these PHP functions in the first lines:

ignore_user_abort(true);
set_time_limit(0);

This causes the script to continue running without time limit when the HTTP connection is closed.

Answer 6

Another way to fork processes is via curl. You can set up your internal tasks as a webservice. For example:

• http://domain/tasks/t1
• http://domain/tasks/t2

Then in your user accessed scripts make calls to the service:

$service->addTask('t1', $data); // post data to URL via curl

Your service can keep track of the queue of tasks with mysql or whatever you like the point is: it's all wrapped up within the service and your script is just consuming URLs. This frees you up to move the service to another machine/server if necessary (ie easily scalable).

Adding http authorization or a custom authorization scheme (like Amazon's web services) lets you open up your tasks to be consumed by other people/services (if you want) and you could take it further and add a monitoring service on top to keep track of queue and task status.

• http://domain/queue?task=t1
• http://domain/queue?task=t2
• http://domain/queue/t1/100931

It does take a bit of set-up work but there are a lot of benefits.