waiting for barcode scanner output, while main program continues to run

[lightframe109]

Hi,

I am trying to accomplish the following situation.
I have a barcodescanner connected by USB to a raspberry pi 4 and I am able to capture the output of the barcode scanner.
How I would like to have the program behave is: the scanner should wait for a barcode that gets scanned, while the main program continues to run and performs other tasks.
My thoughts were to use threading for this, but when I run the code below, the main program is also waiting for the input from the scanner. I think I am missing something, but I can't figure out how to do this.
I hope somebody can help me or guide me in the right direction.

import threading
import serial
import queue

q = queue.Queue()
ser = serial.Serial("/dev/ttyACM0",9600)

def thread_scanner(q):
    try:
        ser.open()
    except IOError:
        ser.close()
        ser.open()

    barcode = ser.readline()
    q.put(barcode)

if __name__ == "__main__":
    scanner_thread = threading.Thread(target=thread_scanner, args=(q,))
    scanner_thread.start()    

    while True:

        if q.qsize > 0:
            barcode = q.get()
            q.task_done()
            print(barcode)
            barcode = ""
        else:
            print("1")
        
        scanner_thread.join()

Thank you in advance.