> the only way I could get it working reliably was with a subprocess
Totally agree.
I've worked in the past on a multi-camera computer vision system in which I used video4linux to capture images from USB cameras which would sometimes misbehave and block on an ioctl() forever. Not even SIGALRM helped.
The only mechanism that could be properly interrupt this situation was a Process, via SIGKILL, which caused OS to clean up all the resources afterwards. Eventually, we connected the cameras to a USB-controlled relay that mechanically replugged the cameras after a certain number of timeouts (ioctl freezes) were exceeded one after another.
Totally agree.
I've worked in the past on a multi-camera computer vision system in which I used video4linux to capture images from USB cameras which would sometimes misbehave and block on an ioctl() forever. Not even SIGALRM helped.
The only mechanism that could be properly interrupt this situation was a Process, via SIGKILL, which caused OS to clean up all the resources afterwards. Eventually, we connected the cameras to a USB-controlled relay that mechanically replugged the cameras after a certain number of timeouts (ioctl freezes) were exceeded one after another.