Results day: the student portal no longer loads

École Supérieure Al Massira (a fictional institution) is publishing the semester results this morning on its portal etudiants.almassira.ma: 6,000 students log in at the same time to download their transcript.

The portal runs on web-em-01: Apache 2.4 (mpm_event) passes PHP pages to PHP-FPM through mod_proxy_fcgi. On Saturday, Hamza migrated the server from PHP 8.1 to PHP 8.3 (“just a package update, the tests pass”).

Since 10:02, pages respond in 40 to 60 s or time out. The on-call developer wants to set MaxRequestWorkers to 2000. Your mission: find the real limit, fix the cause and restore the portal.