Thread per user

ps -u calrisk -o nlwp= | awk '{ num_threads += $1 } END { print num_threads }'
ps --no-headers auxwwwm | awk '$2 == "-" { print $1 }' | sort | uniq -c | sort -n

# 4th parameter number = number of thread
cat /proc/loadavg

# Also with 
ps -eLf | wc -l

Raise limits in /etc/security/limits.conf

calrisk     -    nofile 8192
calrisk     -    nproc unlimited

And system parameters if needed :

echo 120000 > /proc/sys/kernel/threads-max
echo 600000 > /proc/sys/vm/max_map_count
echo 99999 > /proc/sys/kernel/pid_max