Monitor and kill external optional process if status_command no longer matches

[yarikoptic]

inspired by #169 (comment) -- status command was reporting monitor connected since HDMI->VGA dongle was still connected. Now it is no longer connected but we still keep PsychoPy running...

[vmdocua]

The reprostim-videocapture ext_proc_opts.exec_command process tree normally is terminated when status_command+status_regex expression became false and logs look like this - SIGINT and then SIGTERM to entire process tree:

2025-08-12 18:58:52.136 [INFO] [36489] terminating external process with SIGINT
2025-08-12 18:58:52.161 [INFO] [36489] Kill external process, pid: 916261
2025-08-12 18:58:52.161 [INFO] [36489] Kill process, signal=2, pid=916283, result=0
2025-08-12 18:58:52.161 [INFO] [36489] Kill process, signal=2, pid=916267, result=0
2025-08-12 18:58:52.161 [INFO] [36489] Kill process, signal=2, pid=916262, result=0
2025-08-12 18:58:52.161 [INFO] [36489] Kill process, signal=2, pid=916261, result=0

2025-08-12 18:58:53.661 [INFO] [36489] terminating external process with SIGTERM
2025-08-12 18:58:53.680 [INFO] [36489] Kill external process, pid: **925242**

BTW It's strange SIGTERM pid different from SIGINT one, may be there were few commands or some other subprocess in background during termination..need to be investigated in future.

But then this process was forced to be terminated by SIGTERM and there is no explicit external process termination logic executed:

2025-08-13 13:09:33.976 [INFO] [36489] Termination or kill: 15
2025-08-13 13:09:33.988 [INFO] [36489] Termination or kill: 15
2025-08-13 13:09:33.988 [INFO] [36489] Force exit, 2nd attempt

[yarikoptic]

forgot details but may be it was due to stopping the service via systemctl --user stop reprostim-videocapture.service

BTW -- this time stamp in which timezone?

[yarikoptic]

Related , here is how output of our helper looks like when adapter is connected, disconnected, reconnected, and only then VGA attached

reprostim@reproiner:/data/reprostim$ code/xrandr-display0
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 16384 x 16384
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary (normal left inverted right x axis y axis)
   1024x768      60.00 +
   1920x1080     60.00    59.94  
   1280x1024     85.02    60.02  
   1440x900      74.98    59.90  
   1280x960      60.00  
   1360x768      60.02  
   1280x800      59.91  
   1280x720      60.00    59.94  
   720x480       60.00    59.94  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
reprostim@reproiner:/data/reprostim$ code/xrandr-display0
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 16384 x 16384
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected primary (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
reprostim@reproiner:/data/reprostim$ code/xrandr-display0
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 16384 x 16384
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary 1024x768+0+0 (normal left inverted right x axis y axis) 256mm x 192mm
   1024x768      60.00*+
   1920x1080     60.00    59.94  
   1280x1024     85.02    60.02  
   1440x900      74.98    59.90  
   1280x960      60.00  
   1360x768      60.02  
   1280x800      59.91  
   1280x720      60.00    59.94  
   720x480       60.00    59.94  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
reprostim@reproiner:/data/reprostim$ code/xrandr-display0
Screen 0: minimum 320 x 200, current 1280 x 800, maximum 16384 x 16384
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary 1280x800+0+0 (normal left inverted right x axis y axis) 1638mm x 1024mm
   1280x800      59.81*+
   1920x1200     59.95  
   1920x1080     60.00    59.94  
   1600x1200     60.00  
   1680x1050     59.88  
   1400x1050     59.95  
   1600x900      60.00  
   1280x1024     75.02  
   1440x900      59.90  
   1152x864      75.00  
   1280x720      60.00    59.94  
   1024x768     119.99    75.03    70.07    60.00  
   1024x768i     86.96  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   720x480       60.00    59.94  
   640x480       75.00    72.81    60.00    59.94  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)

[vmdocua]

BTW -- this time stamp in which timezone?

I believe this is reproiner box time zone: US/Eastern (EDT, -0400).

[vmdocua]

Related , here is how output of our helper looks like when adapter is connected, disconnected, reconnected, and only then VGA attached

According to logs the video signal always connected to HDMI-2 port, does it make sense to monitor only HDMI-2 one rather than all HDMI ports, e.g. current reprostim-videocapture config.yaml looks like below:

status_regex: "^HDMI-.* connected"

Can be filtered with something like this:

status_regex: "^HDMI-2 connected"

[yarikoptic]

it wouldn't address any issue so I would not bother for now and keep it "flexible".