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Date Published: February 6, 2025

General¶

There is an extensive page on drupal.org for solving problems with cron: Solving cron problems.

There are a few modules aimed at helping debug cron. The one most commonly used is Cron debug for Drupal 7 only.

If you're having problems with cron and search (or think you might be), see Debugging Cron / Search Indexing.

Note
For Acquia Cloud customers, please see the Acquia Cloud page, Using scheduled jobs to support your application, for information on redirecting debug output, and using the cron-wrapper.sh script for debugging.

There are a number of ways to debug issues with cron that are explored here :

Using Drush
- Modules (Drupal 7 only)
- Drush php-eval
Modify Drupal Core

Using Drush¶

Drush offers a multitude of methods to troubleshoot cron and just about everything else.
In this section, we present two methods for debugging cron.

Modules¶

For Drupal 7 only, the Drush Debug Tools are a group of extensions for Drush, written by Acquians, with more extensive cron debug capabilities.

Using php-eval¶

You can debug cron by using the Drush utility using php-eval.

The code below runs drush php-eval using the respective functions :

For Drupal 7 - the module_implements() function
For Current Drupal - the following functions:

The code logs each part of cron as cron runs, and then outputs that to the terminal.

There is a version of the drush php-eval code below, for Drupal 7, and for the current Drupal version, respectively.

Code For Drupal 7¶

drush php-eval 'global $timers; $return = $args = array();foreach (module_implements("cron") as $module) {  $function = $module . "_cron"; print($function ." - ");  timer_start($function); $result = call_user_func_array($function, $args);  if (isset($result) && is_array($result)) { $return = array_merge_recursive($return, $result); }  else if (isset($result)) { $return[] = $result; }  timer_stop  ($function);  print($timers[$function]["time"] ."\r\n");} '

This code will return results like:

ctools_cron - 9.74
field_cron - 83.14
node_cron - 3.91
search_cron - 1.97
system_cron - 1282.06
trigger_cron - 7.53
update_cron - 1036.85

Code For Current Drupal version¶

drush php-eval 'use Drupal\Component\Utility\Timer; foreach(array_keys(\Drupal::moduleHandler()->getModuleList()) as $mod_name) {if(\Drupal::moduleHandler()->hasImplementations("cron", $mod_name)) {print("** Starting execution of " . $mod_name . " cron (" . $mod_name . "_cron()) ... "); Timer::start("time_".$mod_name); \Drupal::moduleHandler()->invoke("cron",$mod_name); Timer::stop("time_".$mod_name); print("Completed Execution of " . $mod_name . "_cron() - time taken:\t" . Timer::read("time_".$mod_name) . "ms" . PHP_EOL . PHP_EOL);} }'

This code will return results like:

** Starting execution of captcha cron (captcha_cron()) ... Completed Execution of captcha_cron() - time taken:  0.01ms

** Starting execution of dblog cron (dblog_cron()) ... Completed Execution of dblog_cron() - time taken:        0.01ms

** Starting execution of field cron (field_cron()) ... Completed Execution of field_cron() - time taken:        0.01ms

** Starting execution of file cron (file_cron()) ... Completed Execution of file_cron() - time taken:   0.01ms

** Starting execution of honeypot cron (honeypot_cron()) ... Completed Execution of honeypot_cron() - time taken:       0.01ms

** Starting execution of layout_builder cron (layout_builder_cron()) ... Completed Execution of layout_builder_cron() - time taken:     0.01ms

** Starting execution of locale cron (locale_cron()) ... Completed Execution of locale_cron() - time taken:     0.01ms

** Starting execution of node cron (node_cron()) ... Completed Execution of node_cron() - time taken:   0.01ms

** Starting execution of purge_processor_cron cron (purge_processor_cron_cron()) ... Completed Execution of purge_processor_cron_cron() - time taken:0.01ms

** Starting execution of scheduler cron (scheduler_cron()) ... Completed Execution of scheduler_cron() - time taken:    0.01ms

** Starting execution of search_api cron (search_api_cron()) ... Completed Execution of search_api_cron() - time taken: 0.01ms

** Starting execution of simple_sitemap cron (simple_sitemap_cron()) ... Completed Execution of simple_sitemap_cron() - time taken:     0.01ms

** Starting execution of system cron (system_cron()) ... Completed Execution of system_cron() - time taken:     0.01ms

** Starting execution of update cron (update_cron()) ... Completed Execution of update_cron() - time taken:     0.01ms

** Starting execution of password_policy cron (password_policy_cron()) ... Completed Execution of password_policy_cron() - time taken:  0.01ms

Modifying Drupal Core (Drupal 7 only)¶

Note
It is not encouraged to modify core, especially for a Production environment! This should be used as a last resort.

Alternately, you can use the following code to help you debug cron. The code is a replacement function that goes in includes/module.inc in place of the existing module_invoke_all() function (for Drupal 7). It logs each part of cron as cron runs, and then logs that to the system log.

There is a version for Drupal 7 :

<?php
/**
 * Invokes a hook in all enabled modules that implement it.
 *
 * @param $hook
 *   The name of the hook to invoke.
 * @param ...
 *   Arguments to pass to the hook.
 *
 * @return
 *   An array of return values of the hook implementations. If modules return
 *   arrays from their implementations, those are merged into one array.
 */
function module_invoke_all($hook) {
  $args = func_get_args();
  // Remove $hook from the arguments.
  unset($args[0]);
  $return = array();
  foreach (module_implements($hook) as $module) {
    // BEGIN CRON LOG
    if ($hook == "cron") {
      watchdog('cron', 'Running cron for: %module', array('%module' => $module), WATCHDOG_NOTICE);
    }
    // END CRON LOG
    $function = $module . '_' . $hook;
    if (function_exists($function)) {
      $result = call_user_func_array($function, $args);
      if (isset($result) && is_array($result)) {
        $return = array_merge_recursive($return, $result);
      }
      elseif (isset($result)) {
        $return[] = $result;
      }
    }
  }

  return $return;
}
?>

Note
Remember to remove this code when you're not actively debugging a problem, because it will fill your logs with additional logging during each cron run.

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