forking php process and tying to specific web user

Question

I have a web app that has a few processes that can take up to 10 minutes to run. Sometimes these processes are triggered by a user and they need the output as it is processed.

For instance, the user is looking for a few records that they need. The click the button to retrieve the records (this is the part that can take 10 minutes). They can continue to work on other things but when they click back to view the returns, it is updated as the records are downloaded into the system.

Right now, the user is locked while the process runs. I know about pcntl_fork() to fork a child process so that the user doesn't have to wait until the long process completes.

I was wondering if it's possible to tie that forked process to the specific user that triggered the request in a $_SESSION variable so that I can update the user when the process is complete. Also, is this the best way to update a user on a long-running process?

I don't think `pcntl_fork` should be used in that context. Forking processes and multi-threaded web servers are known to be problematic. For web applications, you can have asynchronous updates sent to the browser using AJAX instead. — netcoder, Jan 08 '11 at 07:26

score 4 · Accepted Answer · answered Jan 08 '11 at 08:05

I think gearman fits your needs. Look at this sample code, taken from the doc :

<?php

/* create our object */
$gmclient= new GearmanClient();

/* add the default server */
$gmclient->addServer();

/* run reverse client */
$job_handle = $gmclient->doBackground("reverse", "this is a test");

if ($gmclient->returnCode() != GEARMAN_SUCCESS)
{
  echo "bad return code\n";
  exit;
}

$done = false;
do
{
   sleep(3);
   $stat = $gmclient->jobStatus($job_handle);
   if (!$stat[0]) // the job is known so it is not done
      $done = true;
   echo "Running: " . ($stat[1] ? "true" : "false") . ", numerator: " . $stat[2] . ", denomintor: " . $stat[3] . "\n";
}
while(!$done);

echo "done!\n";

?>

If you store the $job_handle in the session, you can adapt the sample to make a control script.

awesome, I knew there was probably a better way, but I've never heard of Gearman before. — Patrick, Jan 08 '11 at 14:17

forking php process and tying to specific web user

1 Answers1