Setting the Max Processes (PIDs) Limit for a User

Every user's user-<uid>.slice cgroup has a TasksMax ceiling - the maximum number of processes/threads (PIDs) the user's account can run at once. This isn't a plan tier customers shop for like CPU, RAM or disk - it's a safety net against fork bombs and runaway processes.

How it's calculated​

By default the PID limit is autocalculated from the user's plan RAM, at a rate of 500 tasks per 1GB of RAM, never below a floor of 1000 tasks. This keeps the limit proportional automatically whenever a plan's RAM value changes, and keeps the smallest plans above the point where ordinary use - a PHP-FPM pool, a cron run and a shell at the same time - fails to fork.

For example, a plan with 4GB RAM gets a TasksMax ceiling of 2000, and every plan up to 2GB gets the floor of 1000. A plan with 0GB (unlimited) RAM gets an unlimited TasksMax as well.

Overriding the limit for a single user​

If a specific user needs a custom PID limit - higher or lower than what their plan's RAM would derive - create a TasksMax file in their home directory containing a single integer:

echo "1000" > /home/<USERNAME>/TasksMax

This file, when present, always takes priority over the autocalculated value for that user.

The same override can be set from HiTechAdmin > Users > (user) > Resource limits > Max processes, or from the terminal:

hitechcloudcli user-limit <USERNAME> --tasks=1000

Both write the TasksMax file, so the value survives the next plan change.

Applying the change​

Creating or editing the TasksMax file does not take effect on its own - the plan must be (re)applied to the user for the new ceiling to be written to their user-<uid>.slice. Run:

hitechcloudcli plan-apply <PLAN_ID> <USERNAME>

Using the user's current plan ID re-applies all of the plan's limits, including the new PID ceiling.

Removing the override​

Delete the TasksMax file and re-run hitechcloudcli plan-apply for the user to fall back to the autocalculated value derived from their plan's RAM:

rm /home/<USERNAME>/TasksMax
hitechcloudcli plan-apply <PLAN_ID> <USERNAME>

Checking the current limit​

hitechcloudcli limits show <USERNAME>
# or straight from systemd
systemctl show user-$(id -u <USERNAME>).slice -p TasksMax