Steamwebhelper possibly overallocating X clients ("Maximum number of clients reachedError: Can't open display: :0")

[redyoshi49q]

Your system information

• Steam client version Thursday, May 25th, 10:25 .p.m. UTC
• Distribution (e.g. Ubuntu): Linux Mint 20.3 Cinnamon
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

I'm posting this as a separate issue from #9094 rather than commenting there because this seems like it might be another lookalike bug relating to X clients (I'll explain why I think that in a moment).

I've periodically entered a state where no GUI windows would spawn. When attempting to spawn something from the command line, an error like the following would result:

1478/64287 MB RAM 10.1% 9.44% 9.25% Sat, Jun 3, 2023 11:09:36 pm [1 jobs]
[ethan@firetail: +2] ~ $ xeyes &
[2] 1499175
Maximum number of clients reachedError: Can't open display: :0
[2]    1499175 exit 1     xeyes

1256/64287 MB RAM 7.56% 9.81% 10.3% Sun, Jun 4, 2023 11:54:33 pm [1 jobs]
[ethan@firetail: +2] ~ $

After researching the issue, I found a helpful comment with a command to run in order to figure out what processes had allocated the most X clients:

1449/64287 MB RAM 10.6% 9.25% 9.88% Mon, Jun 5, 2023 12:10:50 am [1 jobs]
[ethan@firetail: +2] ~ $ lsof | awk '/libX11.so/ {clients[$1]++;} END {for(c in clients){printf "%s\t%s\n", clients[c], c;}}'
4       xapp-sn-w
4       csd-autom
4       csd-power
34      Web\x20Co
130     Discord
4       Utility
50      steam
36      cinnamon
120     Isolated
1       lutris-wr
27      WebExtens
3       lutris
4       mintrepor
4       csd-color
2       oosplash
19      polkit-gn
7       mintUpdat
6       csd-print
5       Socket
4       ibus-exte
6       kdeconnec
14      cinnamon-
4       gnome-ter
3       csd-clipb
4       csd-xrand
2       xprop
93      dropbox
4       csd-orien
74      itch
4       csd-xsett
4       csd-keybo
8       csd-a11y-
3       at-spi-bu
13      winedevic
4       blueman-a
117     firefox-b
20      xed
4       csd-wacom
26      Privilege
4       csd-mouse
4       nm-applet
5       csd-sound
4       ibus-ui-g
20      blueman-m
3       at-spi2-r
3       blueman-t
3       csd-scree
4       csd-backg
5       xplayer-v
32      evolution
5       csd-media
5       soffice.b
1       applet.py
4       xdg-deskt
3       redshift-
1       fontforge
67      telegram
4       redshift
4       RDD\x20Pr
21      nemo
4       nemo-desk
917     steamwebh
4       csd-house
3       csd-curso
138     palemoon
3       ibus-x11
4       goa-daemo

1375/64287 MB RAM 10.7% 9.62% 9.94% Mon, Jun 5, 2023 12:12:23 am [1 jobs]
[ethan@firetail: +2] ~

Based on the 917 clients associated with steamwebh, it seems like the most plausible culprit. The actual steam process has only 50 clients in comparison (unlike what was reported in #9094, where the steam process was the one hoarding all of the connections).

I can produce additional log files if any might prove to be helpful.