Apt lists lock held by python

Source

In my laptop I run Debian Sid. A long time ago I decided to update it only on Sundays afternoon, so if any bugs that might have appeared during the week would have most probability of being either known or already fixed (but probably also means that more bugs can be introduced, assuming Debian Developers work mostly during weekends, so...). I mostly use aptitude but if I have to be honest, I miss the dependency dialogs from dselect: when you selected a package with missing dependencies, a new window showing the automatically added dependencies and also the Recommends and Suggests (mostly because I configured it so Recommends were not selected automatically).

Yesterday I forgot to do the upgrade, so I tried it today. To my surprise, I got this error:

┌────────────────────────────────────────────────────────────────────────────────────────┐
│E: Could not get lock /var/lib/apt/lists/lock. It is held by process 2415644 (python3) ▒│
│W: Be aware that removing the lock file is not a solution and may break your system.   ▒│
│E: Unable to lock directory /var/lib/apt/lists/                                        ▒│
│                                         [ Ok ]                                         │
└────────────────────────────────────────────────────────────────────────────────────────┘

I checked all my open terminals for any stray apt or aptitude running, but I didn't find any. Then I realized it was talking about a python3 process, but both tools are developed in C++. Who's the culprit?

$ ps faux | grep -C 5 2415644
root     2415643  0.0  0.0   9468  3500 ?        Ss   13:04   0:00 /bin/bash -c /usr/share/prometheus-node-exporter-collectors/apt_info.py | sponge /var/lib/prometheus/node-exporter/apt.prom
root     2415644  0.5  0.2  90600 76512 ?        S    13:04   0:00  \_ python3 /usr/share/prometheus-node-exporter-collectors/apt_info.py
_apt     2415651  0.0  0.0  27652 12856 ?        S    13:04   0:00  |   \_ /usr/lib/apt/methods/https
_apt     2415652  0.0  0.0  27628 12820 ?        S    13:04   0:00  |   \_ /usr/lib/apt/methods/https
_apt     2415653  0.0  0.0  17452  5840 ?        S    13:04   0:00  |   \_ /usr/lib/apt/methods/file
_apt     2415654  0.0  0.0  24400  9564 ?        S    13:04   0:00  |   \_ /usr/lib/apt/methods/https
_apt     2415655  0.0  0.0  27624 12972 ?        S    13:04   0:00  |   \_ /usr/lib/apt/methods/https

prometheus-node-exporter-collectors runs every 15m and locks the db. So this is a transient error, although it doesn't go away very quickly. I think I tried 2 or 3 times, then I started writing this post, then I tried again and it worked. Good to know.