Random freezes in (X)Ubuntu 18.04 caused by filled up RAM

Question

I have a problem with random freezes in (X)ubuntu 18.04(.1) under Kernel 4.19.0 and 4.19.4.

When I check 'top' during freeze episodes, I can see that all my RAM and SWAP is slowly beeing consumed by mandb. These freezes occur usually during the first 30 minutes the system has booted - and last for about 5 minutes (until all RAM and SWAP has been consumed).

I started investigating and found out that I can trigger a freeze with any sudo apt install would lead to that behavior. The step 'processing triggers for man-dB (2.8.3-2ubuntu0.1) see screenshot.

Here is the output of ' inxi -F && dmesg | grep -i error'

I searched for "mandb RAM problems in 18.04" and found one thread were a VPN client caused an issue in man-db 2.8.3 - I dont use VPN.

So far I tried:

• updating the Kernel -> same problem
• completely reinstalled the system with Xubuntu 18.04.1 (first I had an upgrade from 16.04 running)

At first, it seemed that the re-installation of the system solved the problem. I was able to install via apt without hick-ups and no more freezes. However, yesterday (one week later) the error starts again.

My main questions are:

• how can I get rid of this?
• Am I the only one with this problem? If so, is it a hardware problem?
• Might it be related to a tool I have installed?

Answer 1

I had the same problem after updating from 16.04 to 18.04, RAM use gradually increasing until everything froze and I had to do a hard reboot. The solution was to choose light DM as the display manager. Install if not already installed.

sudo apt install lightdm

Then choose it

sudo dpkg-reconfigure lightdm

Follow the instructions on the screen, you will be given the choice of GDM3 or lightdm, select lightdm with the arrows and press return. I found that there was no longer a gradual increase in RAM usage after this change.

Answer 2

I was able to fix the Man-DB ram pile up, by recreating the man database via

sudo mandb -c