The error is coming only while printing reports which has more than 150 pages.

• wkhtmltopdf version : 0.12.5 (with patched qt) 
  OS         : Ubuntu 20.04.3 LTS 
  CPU(s)     : 48 
  Memory(RAM): 94GB

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) 377646
max locked memory       (kbytes, -l) 65536
max memory size         (kbytes, -m) unlimited
open files                      (-n) 200000
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 200000
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

odoo configuration file

limit_memory_hard = 78114717696
limit_memory_soft = 65095598080