[Bug 2029120] Re: /usr/bin/unattended-upgrade leaking and saturating RAM in 30 seconds

[Wu Chien Ping]

I've been facing the same problem here.
I use prometheus collecting system metrics as attachment.
Within approximately 30 seconds, the system’s memory usage spiked rapidly and was completely exhausted.

Further investigation showed that the process below was responsible for
the issue. This single process consumed over 18 GB of memory

root      655038  2.4 57.2 20603156 18366636 ?   Rl   13:05   2:26
/usr/bin/python3 /usr/bin/unattended-upgrade --download-only

The process reached 18 GB only because the system ran out of memory — otherwise, its memory usage would have continued to grow beyond this point.
This abnormal behavior caused the system to exhaust all available RAM within seconds.



** Attachment added: "ubuntu memory issues due to unattended-upgrades"
   https://bugs.launchpad.net/ubuntu/+source/unattended-upgrades/+bug/2029120/+attachment/5929287/+files/memory%20leaking.png

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https://bugs.launchpad.net/bugs/2029120

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

Status in unattended-upgrades package in Ubuntu:
  Confirmed

Bug description:
  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.

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