Often you need to adjust php-fpm for the memory available, and to do so you need to average the child processes memory usage.
Human readable:
ps -eo size,pid,user,command --sort -size | awk '{ hr=$1/1024 ; printf("%13.2f Mb ",hr) } { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }' | grep php-fpm
and also machine friendly:
ps -ylC php-fpm --sort:rss
i3 is great window manger, but for some time I had struggles fixing some tearing it had, until I found recently this answer, which fixed it for me.
You will have to install the comptom composite manager with:
sudo apt install compton
then use the following config in ~./config/compton.conf or wherever you prefer to keep you config files. Then place this in that config file:
# basic configuration
backend = "glx";
vsync = "opengl-swc";
glx-copy-from-front = true;
glx-swap-method = 2;
xrender-sync = true;
xrender-sync-fence = true;
# transparancy settings for i3
opacity-rule = [
"0:_NET_WM_STATE@:32a *= '_NET_WM_STATE_HIDDEN'"
];
Or this variation:
backend = "glx"; glx-no-stencil = true; paint-on-overlay = true; vsync = "opengl-swc";
Now you can start compton with that config file to test if it solves the problem for you:
compton --config ~/.config/compton.conf -b
If that work for you, you can place it in your i3wm config file, so it will be loaded on startup –
exec --no-startup-id compton --config ~/.config/compton.conf -b