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raspberrypi / picamera2

New libcamera based python library
BSD 2-Clause "Simplified" License
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[HOW-TO] Reset camera from picamera2.start() after programme crash #1048

Closed Bobo-amg closed 3 months ago

Bobo-amg commented 3 months ago

Is there any way to reset a camera after programme crash?

Scenario: The running python programme using picamera2 crashes. The camera is left in a busy state as per the following error message:

Pipeline handler in use by another process Camera init sequence did not complete. RuntimeError: Failed to acquire camera: Device or resource busy

Aside from restarting the Raspberry Pi, is there any other less obtrusive way to bring the camera back online?

Thanks

davidplowman commented 3 months ago

Hi, could you maybe provide a short example that we can try where the Python program is crashing and leaving the camera in a bad state. I assume you've tried closing the Picamera2 instance, but in the abstract it's a bit hard to guess what may have become unhappy. Sorry not to have any ideas off the top of my head, but if you can provide a bit more detail about how things are going wrong, that would be useful and give us something to look at. Thanks!

Bobo-amg commented 3 months ago

Thanks for quick reply.

Perhaps I have not explained clearly enough. It is not picamera2 that is crashing the programme. It is my shenanigans. Mainly whilst in development mode.

If the programme crashes before the camera is sent a picamera2.stop() then that leaves the camera in "device busy" mode, which then doesn't allow access to it. How can the camera be recovered from this state, without a reboot of the RPi?

Thanks

davidplowman commented 3 months ago

Thanks for the update. I guess I'd still like to get a better idea of how things are broken. For example

I'd have expected picam2.close() might free up the camera, but maybe that's hanging or not working now? I'd also have expected killing the Python process to sort things out too. Unless libcamera underneath or the kernel has become unhappy. Probably worth seeing what rpicam-hello reports after killing your Python process, and if that doesn't work, maybe a look at dmesg.

Bobo-amg commented 3 months ago

The only thing that appears to work is a process KILL command. Strangely, HTOP was unable to kill it (which is what had me baffled), but issuing a KILL from CLI did the job.

Thanks for the help.

davidplowman commented 3 months ago

I guess I'm still curious, but if things are behaving better for you, then that's great!!