Timeout a function in PHP

What you want is to use the pcntl_alarm function, which will trigger a SIGALRM signal on timeout.

For example:

// 10 minutes
pcntl_alarm( 600 );
pcntl_signal(SIGALRM, function() { print( "Timed-out!\n" ); exit( 0 ); });

Please see here the PHP manual for more on this: http://php.net/manual/en/function.pcntl-alarm.php

It depends on your implementation. 99% of the functions in PHP are blocking. Meaning processing will not continue until the current function has completed. However, if the function contains a loop you can add in your own code to interrupt the loop after a certain condition has been met.

Something like this:

foreach ($array as $value) {
  perform_task($value);
}

function perform_task($value) {
  $start_time = time();

  while(true) {
    if ((time() - $start_time) > 300) {
      return false; // timeout, function took longer than 300 seconds
    }
    // Other processing
  }
}

Another example where interrupting the processing IS NOT possible:

foreach ($array as $value) {
  perform_task($value);
}

function perform_task($value) {
    // preg_replace is a blocking function
    // There's no way to break out of it after a certain amount of time.
    return preg_replace('/pattern/', 'replace', $value);
}