/usr/bin/unattended-upgrade leaking and saturating RAM in 30 seconds

[Aurélien]

Hello,
We are facing a huge memory leak with unattended-upgrade binary. It appears that in around 20s, 2.9Go (80%) of RAM is consumed by the process making the system unresponsive (even a basic 'ps' command remains stuck).
The swap was voluntarily disabled, but anyway I do not expect such a process to consume up to 3Go of RAM in nominal operation.

Note: the logs were captured on a system configured in French. I manually translated some words below, which could explain it is not exactly what you would have on an english based system.

Ubuntu release:
Description: Ubuntu 22.04 LTS
Release: 22.04

Package version:
unattended-upgrades:
  Installed : 2.8ubuntu1
  Candidate : 2.8ubuntu1
 Version table :
 *** 2.8ubuntu1 500
        500 http://fr.archive.ubuntu.com/ubuntu jammy/main amd64 Packages
        500 http://fr.archive.ubuntu.com/ubuntu jammy/main i386 Packages
        100 /var/lib/dpkg/status

In attachment you will find 2 files:
- periodic monitoring of available memory (with free -m)
- periodic monitoring of highest memory consumer processes (with ps + sort on memory column)
- screenshot of syslog (from a distinct run) showing that unattended-upgr went out of memory and was killed by OOM. You can also see that the run occured as part of the apt-daily service.

[Ronald Baker (rabbit200)]

Hello, I notice the same problem as reported by Aurélien. It happens daily at the time the unattended upgrades are scheduled. Sometimes it lasts only a minute, sometimes longer. But when it occurs at a moment that an unresponsive system is not acceptable, this causes problems. It consumes 90% memory (32 Gb RAM - swapfile is twice that size)! Until now I didn't notice an out of memory for that process, but it seems that it keeps growing until it fills the whole memory available.

Ubuntu 22.04.3