soft and hard ulimit limits

ychaouche · 12-20-2022, 11:38 AM

Hello LQ,

Tell me about last time you had to use ulimit.

What was it for?

What did you want to achieve?

What limits did you set?

Eager to read you.

wpeckham · 12-20-2022, 12:33 PM

Quote:

Originally Posted by ychaouche

Hello LQ,

Tell me about last time you had to use ulimit.

What was it for?

What did you want to achieve?

What limits did you set?

Eager to read you.

DB server with around 1100 users, 99% connecting using a client application we designed, to control the available resources to each user process and ensure availability for all 1100 at the same time. The default settings were a problem. It took a little tuning, but we got it right in one day. I recall the process, the project, and the events that prompted it but not the final numbers.

sundialsvcs · 12-28-2022, 10:13 AM

We used "ulimit" once to help us identify a memory-leak. Couldn't readily tell which process it was. But we could set a limit and observe which one "blew up." So, that's what we did. Within a few minutes, the culprit had identified itself.

I like the fact that Linux supports both "soft" and "hard" limits. And, a wide variety of limits.

uteck · 12-28-2022, 11:13 AM

When I did support at a hosting company we set each users VM ulimit to 100 to stop them from running a bunch of processes and slowing the whole server down. If they needed more, then they could upgrade to a higher priced plan.