[Test] Test if cgroup pids.max value limits both of processes and threads number

Intro

Test if cgroup pids.max value limits both of processes and threads number using docker with ‘pids-limit’ config.

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Test

Test Environment

• CentOS 7
• Kernel Linux 3.10.0
• Cgroup v1

Test Program

Using a python program creating processes or threads with the number user entered.

• Process mode or thread mode can be selected by set ‘MODE’ environment.
• The number of processes or threads to create can be set by ‘HOWMANY’ environment.
• You can check the README.md file of the git project.
• You can also use the docker image from dockerhub or you can build it yourself using Dockerfile

Python Program Github repo

Docker Image

Create Docker with the ‘ pids-limit’ config and envs used in the test program

For a test, i set cgroup pid limit value to ‘100’ and i tried to create 110 threads.

// example
docker run -i -t -e MODE=thread -e HOWMANY=110 --pids-limit 100 taesunny/cgroupo-pid-max-test:1.2

Result

The program can’t create threads more than cgroup pids limit.

Pid cgroup’s pids.max value limits both of processes and threads number.

• In the test, Cgroup PID Limit value limits also thread numbers.