Prestashop unstable in Amazon AWS + RDS even with a super-configuration

Question

We have right now about 800 users simultaneously online in the website, that is unstable since 3 hours ago, when the client made an publicity with an influencer on instagram.

Server: Apache2 PHP 7.0 MariaDB

AWS: m5.2xlarge (monitoring print: https://imgur.com/a/gBYSLwB ) RDS: db.m5.24xlarge (monitoring print: https://imgur.com/a/UHj0jMM )

Somebody has any ideia why the website is still unstable? Slow and sometimes offline?

Answer 1

At first glance, it seems that your AWS instances could perfectly handle such traffic.

Your performance issues might be related to some SQL-lock behavior:

• Check whether you are using InnoDB or MyISAM tables, prefer InnoDB, you can switch easily
• Turn on slow_query_log in MariaDB and monitor what's happening, a module or specific query might be the one causing your troubles

Here are some other performance improvements you could consider:

• Using Nginx + PHP-FPM rather than Apache
• Using PHP 7.3 rather than PHP 7.0 (~15% performance boost on PrestaShop), this will just require a few PHP warnings to fix
• Enabling and tuning the PHP Opcache (already in PHP 7.x, simply configure it in php.ini )
• Using two separate MariaDB instances, with a Master/slave configuration (you can specify the two servers in the PrestaShop configuration)
• Using mysqltuner to find the optimal MariaDB configuration
• Using a caching module