Question

I’m using pctnl_fork to break a large task into multiple processes and it’s working great except for one annoying thing: for some reason the output has “Content-type: text/html” embedded in it and nothing I do seems able to get rid of it.

Here’s a working example of the issue:

<?php
  ob_start();
  $pid = pcntl_fork();
  if ($pid == -1) {
     die('could not fork');
  } else if ($pid) {
     // we are the parent
     pcntl_wait($status); //Protect against Zombie children
  } else {
     $fh=fopen('/var/www/html/test.txt','w');fwrite($fh, time());fclose($fh);        
     exit(0);
  }

  header_remove();
  ob_end_clean();
  echo " done";
?>

If I omit the header_remove() then it outputs

X-Powered-By: PHP/5.3.3 Content-type: text/html done

With header_remote it gets rid of the X-Powered-By header but the Content-type header remains:

Content-type: text/html done

I’ve pulled my hair out trying to fix this to no avail. I thought for sure ob_end_clean() would fix it but it doesn’t. If anyone has any suggestions I’d be eternally grateful.

Answer 1

Don’t use pcntl_fork() from within web server environments (such as mod_php). As you’ve observed, it does not function correctly when running within the web server, and as such it is not available outside the CLI SAPI in newer versions of PHP.