set_time_limit() - max_execution

PHP Tutorials - Herong's Tutorial Examples

∟set_time_limit() - max_execution_time

This section provides a tutorial example to demonstrate the maximum execution time limit, which is defaulted to 30 seconds only. You can change the default with a set_time_limit() call, or 'max_execution_time' setting in php.ini.

If you are running PHP scripts that take longer time to finish, you may experience the "Maximum execution time of 30 seconds exceeded" error.

By default, PHP does not allow any script to run for more than 30 seconds. But you can change this behavior in several ways:

Call set_time_limit(60*60) inside script - Resets the maximum execution time to 1 hour = 60*60 seconds for running this script only.
Call set_time_limit(0) inside script - Removes the maximum execution time limit, so that the script can run forever. This applies to this script only.
Update max_execution_time = 3600 inside php.ini - Sets the maximum execution time to 1 hour = 3600 seconds for all scripts.
Update max_execution_time = 0 inside php.ini - Removes the maximum execution time limit for all scripts.

The following PHP script, Execution_Time.php, is designed to calculate the execution time and trigger the "Maximum execution time of 10 seconds exceeded" error.

<?php
#- Execution_Time.php
#- Copyright 2003 (c) HerongYang.com. All Rights Reserved.

  set_time_limit(10);
  date_default_timezone_set('Europe/Paris');

  $limit = 1000000;
  $step = 1000;
  $time_0 = time();
  $sleep = 0;
  $work = 0;
  for ($i=$step; $i<$limit; $i+=$step) {

    $time_1 = time ();
    $count = find_primes($i);
    $time_2 = time ();
    $work += $time_2-$time_1;

    sleep(1);
    $sleep++;

    print("Total time: ".(time()-$time_0)
      . ", working: ".$work.", sleeping: ".$sleep
      . ". Primes: $count, within: $i\n");
  }

function find_primes($limit) {
  $count = 0;
  $i = 3;
  while ($i<$limit) {
    $isPrime = true;
    $j = 2;
    while ($j<$i) {
      $isPrime = $i%$j > 0;
      if (!$isPrime) break;
      $j++;
    }
    if ($isPrime) $count++;
    $i++;
  }
  return $count;
}
?>

If you run it, you will get the "Maximum execution time of 10 seconds exceeded" error sooner or later, depending on your CPU speed.

herong$ php Execution_Time.php

Total time: 1, working: 0, sleeping: 1. Primes: 167, within: 1000
Total time: 2, working: 0, sleeping: 2. Primes: 302, within: 2000
Total time: 3, working: 0, sleeping: 3. Primes: 429, within: 3000
Total time: 4, working: 0, sleeping: 4. Primes: 549, within: 4000
Total time: 5, working: 0, sleeping: 5. Primes: 668, within: 5000
Total time: 6, working: 0, sleeping: 6. Primes: 782, within: 6000
Total time: 7, working: 0, sleeping: 7. Primes: 899, within: 7000
Total time: 8, working: 0, sleeping: 8. Primes: 1006, within: 8000
Total time: 10, working: 1, sleeping: 9. Primes: 1116, within: 9000
Total time: 11, working: 1, sleeping: 10. Primes: 1228, within: 10000
Total time: 12, working: 1, sleeping: 11. Primes: 1334, within: 11000
Total time: 14, working: 2, sleeping: 12. Primes: 1437, within: 12000
Total time: 15, working: 2, sleeping: 13. Primes: 1546, within: 13000
Total time: 17, working: 3, sleeping: 14. Primes: 1651, within: 14000
Total time: 18, working: 3, sleeping: 15. Primes: 1753, within: 15000
Total time: 20, working: 4, sleeping: 16. Primes: 1861, within: 16000
Total time: 22, working: 5, sleeping: 17. Primes: 1959, within: 17000
Total time: 24, working: 6, sleeping: 18. Primes: 2063, within: 18000
Total time: 26, working: 7, sleeping: 19. Primes: 2157, within: 19000
Total time: 28, working: 8, sleeping: 20. Primes: 2261, within: 20000
Total time: 30, working: 9, sleeping: 21. Primes: 2359, within: 21000

PHP Fatal error:  Maximum execution time of 10 seconds exceeded
  in /Users/herong/Execution_Time.php on line 36