Nginx cache noob question

While going through the documentation here https://www.nginx.com/blog/inside-nginx-how-we-designed-for-performance-scale/ I found that Nginx loads "cache helper processes" if caching is enabled.

Does this happen only in Nginx Plus, or also happens when one uses simple directives like expire, etc. I tried using expire but I can't see the loaders...


root 29673 13588 0 20:14 pts/1 00:00:00 \_ grep --color=auto nginx
root 19607 1 0 16:24 ? 00:00:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
nginx 29636 19607 0 20:09 ? 00:00:00 \_ nginx: worker process
nginx 29637 19607 0 20:09 ? 00:00:00 \_ nginx: worker process
nginx 29638 19607 0 20:09 ? 00:00:00 \_ nginx: worker process
nginx 29639 19607 0 20:09 ? 00:00:00 \_ nginx: worker process