Increasing nofiles pam ulimit

cat /proc/{process_id}/limits:

$ cat /proc/1882/limits

Limit                     Soft Limit           Hard Limit           Units

Max cpu time              unlimited            unlimited            seconds

Max file size             unlimited            unlimited            bytes

Max open files            4096                 4096                 files

Max locked memory         65536                65536                bytes

it looks like 4096 number is too low for elastic search , now checking if the limit is reached for this PID
 /proc/{process_id}/fd is a directory that holds a file for each open file the process has,
 ls /proc/1882/fd | wc -l


/etc/pam.d/common-session needs to have this line in it:
session required pam_limits.so

/etc/pam.d/common-session-noninteractive also needs to have this line in it:
session required pam_limits.so