Files
docker-php-fpm/php_modules/pcntl

pcntl

Process Control support in PHP implements the Unix style of process creation, program execution, signal handling and process termination. Process Control should not be enabled within a web server environment and unexpected results may happen if any Process Control functions are used within a web server environment.

Platform Url
PHP.net https://www.php.net/manual/en/book.pcntl.php