代码如诗

一个新闻资讯类的新站采用drupal驱动，使用了其上的openpublish集成安装包，在增加了xmlsitemap后提示Cron run failed. 在drupal内置的recent log entries中显示

Attempting to re-run cron while it is already running.

以及在每隔一个小时显示：

Cron has been running for more than an hour and is most likely stuck.

无解，求助google，终于找到：

cron函数的定义在includes/common.inc中function drupal_cron_run(){} 简单的解决方式是在运行corn前删除semaphore值，使cron解锁。如下：

function drupal_cron_run() {

  // If not in 'safe mode', increase the maximum execution time:

     variable_del('cron_semaphore');

并且一些log记录：完整修改drupal_cron_run()代码如下（修改处用粗体表示）：

function drupal_cron_run() {

// If not in ‘safe mode’, increase the maximum execution time:

variable_del(‘cron_semaphore’);

if (function_exists(‘set_time_limit’)) {
@set_time_limit(240);
}

// Fetch the cron semaphore

$semaphore = variable_get(‘cron_semaphore’, FALSE);

if ($semaphore) {

if (time() – $semaphore > 3600) {

// Either cron has been running for more than an hour or the semaphore

// was not reset due to a database error.

watchdog(‘cron’, t(‘Cron has been running for more than an hour and is most likely stuck.’), WATCHDOG_ERROR);

// Release cron semaphore

variable_del(‘cron_semaphore’);

}

else {

// Cron is still running normally.

watchdog(‘cron’, t(‘Attempting to re-run cron while it is already running.’), WATCHDOG_WARNING);

}

}

else {

// Register shutdown callback

register_shutdown_function(‘drupal_cron_cleanup’);

// Lock cron semaphore

variable_set(‘cron_semaphore’, time());

// Iterate through the modules calling their cron handlers (if any):

// module_invoke_all(‘cron’);

$log_timing = variable_get(‘cron_log_times’, ’1′);

foreach (module_implements(‘cron’) as $module) {

watchdog(‘cron’, t(‘Cron processing initiated for module: @module.’, array(‘@module’ => $module)));

if ($module == “search”) continue;

$function = $module .’_cron’;

if ($log_timing) {

timer_start($function);

if ($log_timing == ‘debug’) {

watchdog(‘cron’, t(‘Cron processing initiated for module: @module.’, array(‘@module’ => $module)));

}

}

$function();

if ($log_timing) {

$timer = timer_stop($function);

watchdog(‘cron’, t(‘Cron time elapsed for @module is @millisecs ms.’, array(‘@module’ => $module, ‘@millisecs’ => $timer['time'])));

}

}

// Record cron time

variable_set(‘cron_last’, time());

watchdog(‘cron’, t(‘Cron run completed.’), WATCHDOG_NOTICE);

// Release cron semaphore

variable_del(‘cron_semaphore’);

// Return TRUE so other functions can check if it did run successfully

return TRUE;

}

}

/**

 * Executes a cron run when called

 * @return

 * Returns TRUE if ran successfully

 */

function drupal_cron_run() {

  // If not in 'safe mode', increase the maximum execution time:

     variable_del('cron_semaphore');

  if (!ini_get('safe_mode')) {

    set_time_limit(240);

  }                                                             

  // Fetch the cron semaphore

  $semaphore = variable_get('cron_semaphore', FALSE);

  if ($semaphore) {

    if (time() - $semaphore > 3600) {

      // Either cron has been running for more than an hour or the semaphore

      // was not reset due to a database error.

      watchdog('cron', t('Cron has been running for more than an hour and is most likely stuck.'), WATCHDOG_ERROR);

      // Release cron semaphore

      variable_del('cron_semaphore');

    }

    else {

      // Cron is still running normally.

      watchdog('cron', t('Attempting to re-run cron while it is already running.'), WATCHDOG_WARNING);

    }

  }

  else {

    // Register shutdown callback

    register_shutdown_function('drupal_cron_cleanup');

    // Lock cron semaphore

    variable_set('cron_semaphore', time());

    // Iterate through the modules calling their cron handlers (if any):

    // module_invoke_all('cron');

    $log_timing = variable_get('cron_log_times', '1');

    foreach (module_implements('cron') as $module) {

          watchdog('cron', t('Cron processing initiated for module: @module.', array('@module' => $module)));

 if ($module == "search") continue;

    $function = $module .'_cron';

      if ($log_timing) {

        timer_start($function);

        if ($log_timing == 'debug') {

          watchdog('cron', t('Cron processing initiated for module: @module.', array('@module' => $module)));

        }

      }

      $function();

      if ($log_timing) {

        $timer = timer_stop($function);

        watchdog('cron', t('Cron time elapsed for @module is @millisecs ms.', array('@module' => $module, '@millisecs' => $timer['time'])));

      }

    }

    // Record cron time

    variable_set('cron_last', time());

    watchdog('cron', t('Cron run completed.'), WATCHDOG_NOTICE);

    // Release cron semaphore

    variable_del('cron_semaphore');

    // Return TRUE so other functions can check if it did run successfully

    return TRUE;

  }

}

原文来自：http://www.ebizontek.com/drupal-cron-stuck-log-progress