How to check and modify pids.max of user

1. find out the cgroup of the user

#echo $$|xargs -I '$' cat '/proc/$/cgroup'

/user.slice/user-1000.slice is the cgroup of the user

2. check the pids.max (TasksMax) setting for the user
(1) method 1:
#cgget -a /user.slice/user-1000.slice

(2) method 2:
#cat /sys/fs/cgroup/pids/user.slice/user-1000.slice/pids*

3. modify the pids.max
# systemctl set-property user-1000.slice TasksMax=512

4. verify (using python script)

import time
import threading

def worker():
    while True:
        time.sleep(1000)
        

threads = []
num_worker_threads = 19000
for i in range(num_worker_threads):
    t = threading.Thread(target=worker)
    try:
        t.start()
        threads.append(t)
        print(i)
    except:
        print("EX")
        time.sleep(2000)

for t in threads:
    t.join()

python script:
https://zhuanlan.zhihu.com/p/29192624

cgroup information:
https://access.redhat.com/documentation/zh-tw/red_hat_enterprise_linux/6/html/resource_management_guide/sec-obtaining_information_about_control_groups

xargs:
https://superuser.com/questions/401614/inserting-string-from-xargs-into-another-string