vi /etc/security/limits.conf
vpsee hard nproc 32
@student hard nproc 32
@faculty hard nproc 64

ulimit -u
65535
ulimit -u 65534
ulimit -u 65535
-bash: ulimit: max user processes: cannot modify limit: Operation not permitted
ulimit -a
core file size     (blocks, -c) 0
data seg size      (kbytes, -d) unlimited
scheduling priority       (-e) 0
file size        (blocks, -f) unlimited
pending signals         (-i) 30493
max locked memory    (kbytes, -l) 64
max memory size     (kbytes, -m) unlimited
open files           (-n) 65535
pipe size      (512 bytes, -p) 8
POSIX message queues   (bytes, -q) 819200
real-time priority       (-r) 0
stack size       (kbytes, -s) 10240
cpu time        (seconds, -t) unlimited
max user processes       (-u) 65534
virtual memory     (kbytes, -v) unlimited
file locks           (-x) unlimited

ps h -Led -o user | sort | uniq -c | sort -n
2 nobody
3 redis
34 www
64 mysql
174 root

ps -o nlwp,pid,lwp,args -u username | sort -n