A common installation method for PHP is using php-fpm, typically used by Nginx and often the best method for scaling php processes for your web server. There are performance tweaks needed to the default setup for high requests per second.
This guide requires root access for system settings, and the ability to edit nginx.conf for webserver settings.
/etc/sysctl.conf holds the various OS tweaks for your server. It allows you to tune the performance of your system in general, and particularly what PHP-FPM can achieve. Add these lines to the bottom of your sysctl.conf file:
net.ipv4.tcp_syncookies=1 net.ipv4.conf.all.rp_filter=1 net.ipv4.conf.all.secure_redirects=1 net.ipv4.conf.all.send_redirects=0 net.ipv4.conf.all.accept_source_route=0 net.ipv6.conf.all.accept_source_route=0 net.ipv4.icmp_echo_ignore_broadcasts=1 net.ipv4.tcp_timestamps=0 net.ipv4.tcp_mem=786432 1697152 1945728 net.ipv4.tcp_rmem=4096 4096 16777216 net.ipv4.tcp_wmem=4096 4096 16777216 net.core.rmem_max=16777216 net.core.wmem_max=16777216 net.ipv4.netfilter.ip_conntrack_max=999999 net.netfilter.nf_conntrack_max=999999 net.ipv4.tcp_tw_reuse=1 net.ipv4.tcp_max_orphans=262144 net.ipv4.ip_local_port_range=1000 65535 net.ipv4.tcp_fin_timeout=30 net.core.netdev_max_backlog=10000 net.core.somaxconn=60000 net.ipv4.tcp_synack_retries=3 fs.file-max=640000
The above are general network tweaks in the majority. They are designed to improve the network performance and increase the resources available and are all safe to use as defaults.
Customize your PHP-FPM installations performance by editing the /etc/php/VERSION/fpm/pool.d/www.conf file (replacing version with your version, e.g. 7.4). In particular replace these values below:
pm = dynamic pm.max_children = 50 pm.start_servers = 5 pm.min_spare_servers = 5 pm.max_spare_servers = 20 pm.max_requests = 5000
The above configuration sets the php-fpm process scaling to dynamic, with a maximum of 50 children and allows it to scale in between. The limit of 50 is very high, but you could increase that if needed.
Increasing system file limits
In order to allow PHP to have a large number of open network connections and files you must raise the system limits. Errors with wording like "too many open files" are caused by this.
Add this to the bottom of
/etc/security/limits.conf and replace 'www-data' with your php-cgi user, to allow a higher number of open files (and specifically sockets):
root soft nofile 65536 root hard nofile 65536 www-data soft nofile 65536 www-data hard nofile 65536
Add this to bottom of
/etc/pam.d/common-session to allow the increased limits:
session required pam_limits.so
Add this to bottom of
/etc/systemd/system.conf to set the max open files (and sockets as above):
Now reboot the system to apply your changes. It's possible to apply some of these changes without a reboot but by far the most effective will be a restart.
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