Improved stampede prevention with empty config cache under high loads (#3530)

Co-authored-by: Fabrizio Balliano <[email protected]>
Co-authored-by: Milan Davídek <[email protected]>

Author: 3 people

README.md

@@ -68,8 +68,8 @@ In a nutshell:
 
 ## Requirements
 
-- PHP 7.4+ (PHP 8.0 is supported, PHP 8.1 supported but some warnings may be shown/logged, PHP 8.2 is usable but still being tested)
-- MySQL 5.6+ (8.0+ recommended) or MariaDB
+- PHP 7.4 to 8.2
+- MySQL 5.7+ (8.0+ recommended) or MariaDB
 - optional: Redis 5.x, 6.x and 7.0.x are supported
 
 

app/code/core/Mage/Core/Model/Config.php

@@ -502,18 +502,19 @@ public function getCache()
      */
     public function getCacheSaveLock($waitTime = null, $ignoreFailure = false)
     {
-        if (! Mage::app()->useCache('config')) {
+        if (!Mage::app()->useCache('config')) {
             return;
         }
-        $waitTime = $waitTime ?: (PHP_SAPI === 'cli' ? 60 : 3);
+        $waitTime = $waitTime ?: (getenv('MAGE_CONFIG_CACHE_LOCK_WAIT') ?: (PHP_SAPI === 'cli' ? 60 : 3));
         $connection = Mage::getSingleton('core/resource')->getConnection('core_write');
         if (!$connection->fetchOne("SELECT GET_LOCK('core_config_cache_save_lock', ?)", [$waitTime])) {
             if ($ignoreFailure) {
                 return;
             } elseif (PHP_SAPI === 'cli') {
                 throw new Exception('Could not get lock on cache save operation.');
             } else {
-                require_once Mage::getBaseDir() . DS . 'errors' . DS . '503.php';
+                Mage::log(sprintf('Failed to get cache save lock in %d seconds.', $waitTime), Zend_Log::NOTICE);
+                require Mage::getBaseDir() . DS . 'errors' . DS . '503.php';
                 die();
             }
         }
@@ -526,7 +527,7 @@ public function getCacheSaveLock($waitTime = null, $ignoreFailure = false)
      */
     public function releaseCacheSaveLock()
     {
-        if (! Mage::app()->useCache('config')) {
+        if (!Mage::app()->useCache('config')) {
             return;
         }
         $connection = Mage::getSingleton('core/resource')->getConnection('core_write');