deja-dup-monitor eats RAM/CPU while trying to modify dconf user file

[Adam Colligan]

As far as I know, I don't have deja-dup set up to do anything.

Behavior: While using other applications, the system became nearly unusable, with inputs ignored or heavily lagging. The CPU fan was periodically cycling into high RPM. I could not even open another TTY. Eventually, GUI authentication messages started showing up asking for authorization to modify my user data.

After much patience, I was able to open a System Monitor GUI and see that deja-dup-monitor was using over 10GB of RAM (out of 12GB on the machine). Killing this task ended the issue.

Syslog shows a number of dconf-related messages about permissions denied while trying to create file /run/user/1000/dconf/user . This affected many applications, and some of them were condensed into "message repeats X times". In the case of deja-dup-monitor, however, the message repeated thousands of times.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: deja-dup 34.2-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-18.34-generic 4.4.6
Uname: Linux 4.4.0-18-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Apr 17 08:04:09 2016
InstallationDate: Installed on 2014-08-10 (616 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
SourcePackage: deja-dup
UpgradeStatus: Upgraded to xenial on 2016-03-26 (21 days ago)

[Vej (vej)]

Is this a duplicate of bug #1302416 ?

[Adam Colligan (adam-p)]

It's possible that it's the same bug as bug #1302416 , but I don't know that there's specific evidence supporting that.

- Most (though not all) of the users reporting that bug experience it in conjunction with Chrome Remote Desktop, which I don't use and don't have installed as far as I know.

- Most of the users reporting that bug seem to indicate that it behaves this way consistently -- or at least consistently after an upgrade. The bug I experienced was novel to my system, and it had been over a week since deja-dup was upgraded. The last update of packages generally was many hours before this problem showed up.

- This bug appeared in conjunction with what I think is a separate underlying error -- something interfering with applications' ability to create the /run/user/1000/dconf/user file. A lot of "critical" errors were/are being logged in various terminals/logs about it during this session. However, deja-dup appears to be the only application whose handling of the problem generated thousands of failure messages and was accompanied by drastic consumption of system resources and resulting instability.