i3 Multiple Terminal Issue

I have a software issue on my laptop that I have not been able to resolve yet. I am using the i3 window manager, and the command that should open one terminal occasionally opens two terminals.

I have only experienced this issue on my laptop when running Arch Linux. I did not experience the issue when using NixOS or Debian on the same laptop, using the same configuration files. At this point, I am not sure if the issue is with i3, other software, or the hardware. I have searched i3 issues and /r/i3wm but have not been able to find any information about this issue.

$ i3 --version
i3 version 4.19.2 (2021-02-27) © 2009 Michael Stapelberg and contributors
$ pacman -Q xorg-server
xorg-server 1.20.11-1
$ uname -srv
Linux 5.12.2-arch1-1 #1 SMP PREEMPT Fri, 07 May 2021 15:36:06 +0000

Key Mapping

I use the Windows key as my modifier key. My laptop only has a left Windows key, identified as Super_L with key code 0x85.

$ xmodmap
xmodmap:  up to 4 keys per modifier, (keycodes in parentheses):

shift       Shift_L (0x32),  Shift_R (0x3e)
lock        Eisu_toggle (0x42)
control     Control_L (0x25),  Control_R (0x69)
mod1        Alt_L (0x40),  Alt_R (0x6c),  Meta_L (0xcd)
mod2        Num_Lock (0x4d)
mod3
mod4        Super_L (0x85),  Super_R (0x86),  Super_L (0xce),  Hyper_L (0xcf)
mod5        ISO_Level3_Shift (0x5c),  Mode_switch (0xcb)

$ grep '^set $mod' ~/.config/i3/config
set $mod Mod4

Pressing Win+Enter is configured to open a terminal.

$ grep '^bindsym $mod+Return' ~/.config/i3/config
bindsym $mod+Return exec i3-sensible-terminal

Debugging

Logging can be enabled to help with debugging i3.

$ grep '^exec i3' ~/.xinitrc
exec i3 --shmlog-size=26214400

Without logging enabled, I experience the issue very frequently. I have not measured, but I estimate that the issue occurs with greater than 50% probability. With logging enabled, I experience the issue very infrequently. After enabling logging yesterday morning, it took 9 hours before I experienced the issue. After occurring once, it seemed to occur more frequently but still not as frequent as without logging enabled. My laptop has not been rebooted, and I have yet to experience this issue this morning.

Inspecting the logs, I find that i3 handles two KeyPress events when the issue occurs. The logs are very verbose, but each KeyPress log is like the following:

... - ../src/handlers.c:handle_event:1271 - event type 2, xkb_base 85
... - ../src/key_press.c:handle_key_press:23 - KeyPress 36, state raw = 0x40

Here is the relevant i3 source:

• src/handlers.c
• src/key_press.c

Using xev, I confirmed that KeyPress 36 is indeed the enter key.

KeyPress event, serial 31, synthetic NO, window 0x4c00001,
    root 0x6ac, subw 0x0, time 85317718, (387,292), root:(391,314),
    state 0x0, keycode 36 (keysym 0xff0d, Return), same_screen YES,
"   XLookupString gives 1 bytes: (0d) "
"   XmbLookupString gives 1 bytes: (0d) "
    XFilterEvent returns: False

Thoughts

The fact that the issue does not occur consistently may indicate that it is caused by a race condition somewhere. The fact that enabling logging in i3 significantly reduces the frequency of occurrences may indicate that it is an i3 issue.

I have not ruled out a hardware issue, particularly because this laptop has had different problems with other operating systems. I tend to use laptops until they fail completely, but perhaps it is about time for a new laptop…

I have had this issue since installing Arch Linux on the laptop just over one year ago.

$ sudo dumpe2fs /dev/sda2 | grep 'Filesystem created:'
dumpe2fs 1.46.2 (28-Feb-2021)
Filesystem created:       Sun May  3 16:22:37 2020

Resolving the issue has not been a priority, as it is only an annoyance, but I would really like to solve it. This laptop is my primary development system, however, so I am not willing to perform tests/experiments that would interrupt my normal usage. At this time, I do not want to switch to Wayland and Sway.