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After a user submits a form, I want to render a view file, and right after that I want to initiate a background task to process five MS Excel files (each may have up to 2000 rows) , but in way so that the user don't have to wait for the process to finish in order to view the page. After the task is finished I will inform the user through an email.

I am using Symfony Framework 3. I have included my code below. Its not doing what I am trying to achieve. After submitting the form the page loads only when the entire background task is complete.

I am not sure but after googling a lot, I think The kernel.terminate Event could be useful here. But I can't seem to understand how to work with it.

Could you please tell me how to solve this problem ?

Here's my code:

I have created a Console Command:

class GreetCommand extends ContainerAwareCommand {

  protected function configure()
  {
    $this->setName('hello:world');
  }

  protected function execute(InputInterface $input, OutputInterface $output)
  {
   // My code to execute
  }

}

And in my controller I have 

$process = new Process('ls -lsa');
$process->disableOutput();
$that = $this;

$process->start(function ($type, $buffer) use ($that) {
        $command = new GreetCommand();
        $command->setContainer($this->container);
        $input = new ArrayInput(array());
        $output = new NullOutput;
        $resultCode = $command->run($input, $output);

 });

 return $this->render('success.html.php',  array('msg' => 'Registraion Successful'));

Update

I have solved the problem using the connection-handling feature of PHP.

Thanks to this post

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2
  • 3
    It would be useful to update your post with a little bit of info regarding the implementation of connection-handling feature! Commented Nov 6, 2016 at 9:10
  • @mpilliador - you could simply create an event listener on kernel.terminate or run process asynchronously (see Denis Alimov answer below). Commented Dec 29, 2016 at 10:01

7 Answers 7

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27

Running Processes Asynchronously

You can also start the subprocess and then let it run asynchronously, retrieving output and the status in your main process whenever you need it. Use the start() method to start an asynchronous process

documentation

so, to start your command asynchronously you should create new process with command and start it

$process = new Process('php bin/console hello:word');
$process->start();

Consider to change this to full paths like \usr\bin\php \var\www\html\bin\console hello:word

Also there is good bundle cocur/background-process you may use it, or at least read the docs to find out how it works.

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8 Comments

Thank you very much for your answer. I already tried the above code, but its still waiting for the process to finish and then rendering the page. Do you think its because I am on windows, may be if I move to Linux it would work?
@black_belt yep, this maybe the cause of this.
@black_belt, no. it is not because you are on windows. Your main process is the application that launches the process. The output stream of sub-process is attached to the main process and it will block application process from termination until child press finishes.
This answer does not sound right. It says in the doc: "If a Response is sent before a child process had a chance to complete, the server process will be killed (depending on your OS)." That's the opposite of what the question asked for.
@Alexander Rechsteiner you are looking at Symfony 4 documentation. 2 years ago we were talking about Symfony 2 I guess.
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9

I am a bit late to the game, but I just found a solution for this problem using the fromShellCommandLine() method:

use Symfony\Component\Process\Process;

Process::fromShellCommandline('/usr/bin/php /var/www/bin/console hello:world')->start();

This way it is possible to start a new process/run a command asynchronously.

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1 Comment

Please note, this is only available in 4.3+.
9

Simple use Symfony Process Options

create_new_console

From Symfony Process Source:

 /**
  * Defines options to pass to the underlying proc_open().
  *
  * @see https://php.net/proc_open for the options supported by PHP.
  *
  * Enabling the "create_new_console" option allows a subprocess to continue
  * to run after the main process exited, on both Windows and *nix
  */
  public function setOptions(array $options)

So lets do it this way:

$process = new Process($cmds);
$process->setOptions(['create_new_console' => true]);
$process->start();
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3 Comments

On windows, it launches command prompt. Is there any way to avoid opening command prompt.
I couldn't find a way from PHP. Anyway, even if you close the prompt manually, your process will still keep running. So perhaps it's possible by analyzing windows taskmanager and calling some specific windows task command in shell. Have a look at superuser.com/a/1189987
this helps if the request has bee finished before script ends running :-)
7

For using in controller:

use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\HttpKernel\Event\PostResponseEvent;

$myVar = new MyObject();
$this->get('event_dispatcher')->addListener(KernelEvents::TERMINATE, function(PostResponseEvent $event) use($myVar) {
    //You logic here
    $request = $event->getRequest();
    $test = $myVar->getMyStuff();
});

But it is not a good practice, please read about normal registering event listeners

kernel.terminate event will be dispatched after sending the response to user.

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5

There is a bundle called AsyncServiceCallBundle which allows you to call your service's methods in background.

You can refer this answer for more details about how it is done internally. Everything you need is to invoke your service's method as follows:

$this->get('krlove.async')->call('service_id', 'method', [$arg1, $arg2]);
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4

I guess what you want is to store the necessary data in a database and then have a cronjob/queue execute the actual command, instead of trying to execute it directly from your controller.

Add something like the following to your /etc/crontab to let it run your command every 5 minutes

*/5 * * * * root /usr/bin/php /path/to/bin/console hello:world

Then, let your command query the database for the stored data and have it process the excel files

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0

Even though it's already answered,
I post here my working solution if any one is need of.
In my Controller

public function exportDossiersAction(Request $request)
{    
    $form = $this->createForm(ExportType::class, null, []);
    $form->handleRequest($request);

    if ($form->isSubmitted() && $form->isValid()) {
        $filters = ["status" => $form->get('status')->getData()];

        $phpBinaryFinder = new PhpExecutableFinder();
        $phpBinaryPath = $phpBinaryFinder->find();
        $projectRoot = $this->get('kernel')->getProjectDir();

        $process = new Process([$phpBinaryPath, $projectRoot . '/bin/console', 'myapp:files:export', json_encode($filters)]);
        $process->setTimeout(36000); //10min

        // let the process run in the background
        $this->get('event_dispatcher')->addListener(KernelEvents::TERMINATE, function() use($process) {
            $process->start();
            $process->wait();
        });

       // render this messsage in twig
        $this->addFlash("success", "The export files is initiated");

        return $this->redirectToRoute('home');
     }

   return $this->render('$PATH/export.html.twig', [
        'form' => $form->createView()
    ]);
}
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