nohang: both nohang tests failed on Ubuntu 18.04

I have installed nohang as described. Then

$ sudo systemctl enable nohang-desktop
$ sudo systemctl start nohang-desktop
$ nohang --memload

And guess what - system freezed. After waiting for 10 minutes I performed a power cycle. After booting I checked if nohang is running with $ systemctl list-units

This time I tried $ tail /dev/zero The system freezed again.

Is this me doing something wrong or the app? For me as a user this behaviour is not expected.

About this issue

Original URL
State: open
Created 4 years ago
Comments: 23 (11 by maintainers)

Most upvoted comments

The transition introduces a bunch of problems. The conclusion is based on my previous experience. Too many things change at once. I still miss some Unity features. Something got broken. For example, manually added repositories don’t work anymore. I should be ready to spend an uncertain amount of time fixing my user and dev environments.

lvitya on Mar 31, 2023

I upgraded to 20.04.

lvitya on Mar 31, 2023

One more question is why after killing the hog process the memory isn’t freed?

Processes do not free memory immediately after receiving a signal, even if it is SIGKILL. Freeing up memory can take up to several seconds. See also https://github.com/rfjakob/earlyoom/issues/128#issuecomment-507019219

hakavlad on Jun 13, 2020

Maybe you would run sudo apt install --install-recommends linux-generic-hwe-18.04 xserver-xorg-hwe-18.04 to install 5.3 with PSI support.

So I have installed Linux kernel 5.3.0 according to provided suggestion. Now nohang tests don’t lead to Ubuntu freeze. Thank you.

One more question is why after killing the hog process the memory isn’t freed? See, for example, this log after tail test. https://gist.github.com/lvitya/7241dda5b3f7723d84cfec41c55779f6

Memory status after implementing a corrective action: MemAvailable: 164.9 MiB, SwapFree: 1467.9 MiB

lvitya on Jun 3, 2020

PSI required to prevent freezing under heavy swapping.

You could install the new kernel (4.20+), maybe 5.0 or 5.3.

Demo: https://youtu.be/Y6GJqFE_ke4

hakavlad on May 28, 2020

Hi! I’d like to see the output:

$ uname -a

$ cat /proc/swaps

$ cat /proc/sys/vm/swappiness

$ cat /proc/pressure/memory

hakavlad on May 28, 2020