fingerpaint takes ~15-50 seconds to exit after window is closed #29
Description
fingerpaint is great! Thanks for creating such a simple, useful tool! I wanted to report a minor problem I've noticed during my early usage. I'm running fingerpaint-wayland 1.2.7-1 installed via paru on Arch/Wayland/Hyprland.
Every time I've run the simplest fingerpaint -o mysig.png, after exiting the GUI window, the fingerpaint process in terminal hangs for a long variable time, so far it's been between 20-50 seconds, before writing the file and exiting. If I hit Ctrl-C early on, even immediately after the window exits, fingerpaint writes the (correct) file to disk and exits.
So there appears to be something in the program that's blocked and timing out after a long variable amount of time. Monitoring the 2 fingerpaint processes, I can see that during this waiting time, one of them appears to be spinning, using over 100% of one of my machine's CPUs for the entire duration.
Running the same fingerprint incantation under strace, I see in its resulting output (attached as compressed file bc of its size), that fairly early on (around line 82006 out of 3.6 million), which appears to be around the time the child process for the GUI window exits, there begins a cycle of polling file descriptor 4 and other probably-related file-mutexy things.
The cycle ends around line 3609225. Thereafter it's "doing tcl/tk stuff" which seems to indicate maybe the hang is in that library, something related to closing a window, maybe in wayland. This is all but confirmed in the remainder of the strace, from line 3609280 to the end, which clearly logs the writing of the output png file and exiting.
So, this does appear to be something related to the usage of TCL/Tk related to closing a window. Hope all this info helps.