PHP's unit of concurrency is the shared-nothing web request. [1] It has proved a very successful model, combined with tools that cache PHP bytecode like opcach

PHP's unit of concurrency is the shared-nothing web request. [1] It has proved a very successful model, combined with tools that cache PHP bytecode like opcache, and keep a pool of reusable PHP workers like php-fpm. [1] https://slack.engineering/taking-php-seriously/ https://slack.engineering/taking-php-seriously/