Dear Maintainer,

every other time when I install updates using the synaptic package manager, it
gets interrupted by packagekitd locking the dpkg frontend leading to error
messages like this one I got today:
Preparing to unpack .../locales_2.36-9+deb12u4_all.deb ...
Unpacking locales (2.36-9+deb12u4) over (2.36-9+deb12u3) ...
dpkg: error: dpkg frontend lock was locked by another process with pid 567573
Note: removing the lock file is always wrong, can damage the locked area
and the entire system. See <https://wiki.debian.org/Teams/Dpkg/FAQ#db-lock>.
E: Sub-process /usr/bin/dpkg returned an error code (2)
A package failed to install.  Trying to recover:
dpkg: error: dpkg frontend lock was locked by another process with pid 567573
Note: removing the lock file is always wrong, can damage the locked area
and the entire system. See <https://wiki.debian.org/Teams/Dpkg/FAQ#db-lock>.

This was the error message in synaptic package manager and when I looked up pid
567573 it turned out to be packagekitd

Please do not ever lock dpkg while it is in use by another program!

Thanks,
Daniel

Hi Julian (now CC'ed)!

Do you have any idea how this would be possible? Both PK and Synaptic
should hold the APT frontend lock, so they should never be able to run
at the same time.
I also have never once observed this behavior...

Cheers,
    Matthias

If packagekit checks for the lock (I assume you claim it does), isn't it
synaptics fault to not grab the lock? I.e. isn't this bug filed against
the wrong package?

Paul

Both synaptic and PackageKit need to support the frontend lock, I don't
know if they do, that may involve calling UnLockInner() rather than
UnLock(), and LockInner() rather than Lock() to regain released inner
locks in some places.

Control: reassign -1 synaptic
Control: retitle -1 synaptic: releases frontend lock while running dpkg

synaptic calls releaseLock() before running dpkg; which in turn calls
APT's UnLock(). I believe, but am not sure, that we can drop that call
entirely and APT should do the right thing.

I don't quite know and I'd need to do more investigation and a trial
and error attempt :D

On Sat, Apr 5, 2025, at 00:00, Julian Andres Klode wrote:
[..]

Thanks for the bugreport and the help diagnosing it!
I pushed a small change into https://github.com/mvo5/synaptic/commit/928ce5bd19bdd810a6920831a8d738d016edb2d8
that should fix it and will upload shortly.

Thanks,
 Michael

We believe that the bug you reported is fixed in the latest version of
synaptic, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1062190@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Michael Vogt <mvo@debian.org> (supplier of updated synaptic package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Sun, 06 Apr 2025 21:12:43 +0200
Source: synaptic
Architecture: source
Version: 0.91.7
Distribution: unstable
Urgency: medium
Maintainer: Michael Vogt <mvo@debian.org>
Changed-By: Michael Vogt <mvo@debian.org>
Closes: 1062190
Changes:
 synaptic (0.91.7) unstable; urgency=medium
 .
   * common: use `_system->{,Un}LockInner()`
     (Closes: #1062190)
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