I don't seem to see a mention of the file descriptor limit. As recently as last year the default on Ubuntu was 2048 iirc, which is laughable given that it was 2

I don't seem to see a mention of the file descriptor limit. As recently as last year the default on Ubuntu was 2048 iirc, which is laughable given that it was 2014. I guess it's not strictly performance related, but should definitely be one of the first parameters to tune. # in in /etc/sysctl.conf: fs.file-max = 100000 # then: sudo sysctl -p # in /etc/security/limits.conf * soft nofile 100000 * hard nofile 100000 # then: ulimit -n 100000 (tweak the exact number as required)