Gpib.__del__ fails on script end

I'm rather new to python on Linux, so apologies if I miss anything obvious. I'm also not certain if this is an actual issue or I just need support, but I appreciate any assistance all the same.

My test system is basically a glorified thermometer at the moment, with the following script to get a single measurement:

import pyvisa

inst = pyvisa.ResourceManager('@py').open_resource('GPIB0::8::INSTR')

inst.write('MEAS:VOLT:DC? (@103)')
rawMeas = inst.read()

fmtMeas = '{:.2f}C'.format(float(rawMeas) * 1000)
print(fmtMeas)

This will print the value I'm looking for but won't terminate cleanly:

 pi@raspberrypi:~/Documents/py_scratches $ /usr/bin/python3
/home/pi/Documents/py_scratches/Temp_Tester.py
21.61C
libgpib: invalid descriptor
libgpib: invalid descriptor
Exception ignored in: <function Gpib.__del__ at 0x7475eb70>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/Gpib.py", line 32, in __del__
gpib.GpibError: close() failed: One or more arguments to the function call were invalid.

This error doesn't occur using python 2.7.16. It also does not occur when using Gpib directly with inst = Gpib.Gpib(0,8) on 3.7.3, which is why I figured it has to do with pyvisa-py.

My module info:

pi@raspberrypi:~/Documents/py_scratches $ python3 -m visa info
Machine Details:
   Platform ID:    Linux-4.19.75-v7+-armv7l-with-debian-10.2
   Processor:      

Python:
   Implementation: CPython
   Executable:     /usr/bin/python3
   Version:        3.7.3
   Compiler:       GCC 8.2.0
   Bits:           32bit
   Build:          Apr  3 2019 05:39:12 (#default)
   Unicode:        UCS4

PyVISA Version: 1.10.1

Backends:
   ni:
      Version: 1.10.1 (bundled with PyVISA)
      Binary library: Not found
   py:
      Version: 0.3.1
      ASRL INSTR: Available via PySerial (3.4)
      USB INSTR: Available via PyUSB (1.0.2). Backend: libusb1
      USB RAW: Available via PyUSB (1.0.2). Backend: libusb1
      TCPIP INSTR: Available 
      TCPIP SOCKET: Available 
      GPIB INSTR: Available via Linux GPIB (< 4.0)

and the output with log_to_screen():

pi@raspberrypi:~/Documents/py_scratches $ /usr/bin/python3 /home/pi/Documents/py_scratches/Temp_Tester.py
2020-01-21 15:07:38,684 - pyvisa - DEBUG - SerialSession was correctly imported.
2020-01-21 15:07:38,749 - pyvisa - DEBUG - USBSession and USBRawSession were correctly imported.
2020-01-21 15:07:38,766 - pyvisa - DEBUG - TCPIPSession was correctly imported.
2020-01-21 15:07:38,771 - pyvisa - DEBUG - GPIBSession was correctly imported.
2020-01-21 15:07:38,772 - pyvisa - DEBUG - Created library wrapper for unset
2020-01-21 15:07:38,773 - pyvisa - DEBUG - Created ResourceManager with session 9700303
2020-01-21 15:07:38,774 - pyvisa - DEBUG - GPIB0::8::INSTR - opening ...
2020-01-21 15:07:38,777 - pyvisa - DEBUG - GPIB0::8::INSTR - is open with session 3920073
2020-01-21 15:07:38,777 - pyvisa - DEBUG - GPIB.write b'MEAS:VOLT:DC? (@103)\r\n'
2020-01-21 15:07:38,782 - pyvisa - DEBUG - GPIB0::8::INSTR - reading 20480 bytes (last status <StatusCode.success_max_count_read: 1073676294>)
21.61C
2020-01-21 15:07:39,104 - pyvisa - DEBUG - GPIB0::8::INSTR - closing
2020-01-21 15:07:39,105 - pyvisa - DEBUG - GPIB0::8::INSTR - is closed
2020-01-21 15:07:39,143 - pyvisa - DEBUG - Closing ResourceManager (session: 9700303)
libgpib: invalid descriptor
libgpib: invalid descriptor
Exception ignored in: <function Gpib.__del__ at 0x7476da98>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/Gpib.py", line 32, in __del__
gpib.GpibError: close() failed: One or more arguments to the function call were invalid.

For what it's worth, I noticed running against 2.7 with log_to_screen() that the final "Closing ResourceManager" message is not printed.

pyvisa / pyvisa-py

Gpib.del fails on script end #218

pyvisa / pyvisa-py

Gpib.__del__ fails on script end #218

Gpib.del fails on script end #218