Unable to KeyboardInterrupt when ImageAcquirer exists

[zamzz]

Describe the Issue
Keyboard Interrupt / Ctrl+C isn't being caught/acknowledged when an ImageAcquirer is in existence. Interesting that quit() instead of Ctrl+C works for me.

Sample Code
I can show a piece of code that demonstrates the reported phenomenon:

• Yes
• No

If yes, please provide a sample code:

Stops on KeyboardInterrupt once "waiting!" starts printing:

import time
from harvesters.core import Harvester


if __name__ == "__main__":
    h = Harvester()
    h.add_file("")  # insert producer path here
    h.update()

#    with h.create() as ia:
#        pass
    
    while True:
        print("waiting!")
        time.sleep(1)

Doesn't stop on KeyboardInterrupt once "waiting!" starts printing:

import time
from harvesters.core import Harvester


if __name__ == "__main__":
    h = Harvester()
    h.add_file("")  # insert producer path here
    h.update()

    with h.create() as ia:
        pass
    
    while True:
        print("waiting!")
        time.sleep(1)

Expected Behavior

Configuration

• OS: Ubuntu 22.04
• Python: 3.8
• Harvester: 1.4.3

Reproducibility

This phenomenon can be stably reproduced:

• Yes
• No.

If applicable, please provide your observation about the reproducibility.
I'm unsure if this happens with other cameras (or producers to be honest).

Actions You Have Taken

• I've read the Harvester FAQ page.
• I've found this issue that seems quite similar

[KABILAN235]

I've got the same problem too and haven't found a solution yet

[basfee]

Came across the same issue. I looked into it. Creation of the ImageAcquirer object registers a handler for SIGINT. It seems that this overrides the default handler that normally raises the KeyboardInterrupt.

See

harvesters/src/harvesters/core.py

Line 1698 in 383494e

signal.signal(signal.SIGINT, self._sigint_handler)

Looks like it is used to destroy the ImageAcquisition object. Potential workaround (I'm not sure if this is ideal) is to register your own handler again and raising KeyboardInterrupt. If you do this after ImageAcquisition object is created, it will override that one again..

import time
import signal
from harvesters.core import Harvester


if __name__ == "__main__":
    h = Harvester()
    h.add_file("")  # insert producer path here
    h.update()

    with h.create() as ia:
        pass

    def sigint_handler(self, frame):
        raise KeyboardInterrupt
    signal.signal(signal.SIGINT, sigint_handler)
    
    while True:
        print("waiting!")
        time.sleep(1)

Perhaps you could call ImageAcquisition its handler from your own handler to keep Harvester behave the same ?