ni / ni/nimi-python

Mixing an nidmm PXI-407x session and niswitch sessions causes unexpected failures finding the NI-SWITCH Functions on Linux

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Description

Description of issue

Using Python 3.9.15, NI-DMM 23.5 and the nidmm 1.4.5 python package, I get weird behavior when using a 407x device and mixing usage of NI-DMM and NI-SWITCH sessions (used the niswitch 1.4.5 package, but I also reproduced with the nidcpower 1.4.5 package).

Specifically after running a very small program (listed below in the steps to reproduce) that includes opening an NI-DMM session, calling dmm.initiate(), and then opening an NI-SWITCH Session, I get the following error:

Traceback (most recent call last):
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/site-packages/niswitch/_library.py", line 65, in _get_library_function
    function = getattr(self._library, name)
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/ctypes/__init__.py", line 387, in __getattr__
    func = self.__getitem__(name)
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/ctypes/__init__.py", line 392, in __getitem__
    func = self._FuncPtr((name_or_ordinal, self))
AttributeError: /home/user/.pyenv/versions/3.9.15/bin/python: undefined symbol: niSwitch_InitWithTopology

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/user/./switch_reproducer.py", line 6, in <module>
    with niswitch.Session(resource_name="", topology="2535/1-Wire 4x136 Matrix", simulate=True) as session1:
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/site-packages/niswitch/session.py", line 1377, in __init__
    self._interpreter.set_session_handle(self._init_with_topology(resource_name, topology, simulate, reset_device))
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/site-packages/niswitch/session.py", line 1993, in _init_with_topology
    vi = self._interpreter.init_with_topology(resource_name, topology, simulate, reset_device)
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/site-packages/niswitch/_library_interpreter.py", line 293, in init_with_topology
    error_code = self._library.niSwitch_InitWithTopology(resource_name_ctype, topology_ctype, simulate_ctype, reset_device_ctype, None if vi_ctype is None else (ctypes.pointer(vi_ctype)))
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/site-packages/niswitch/_library.py", line 225, in niSwitch_InitWithTopology
    self.niSwitch_InitWithTopology_cfunc = self._get_library_function('niSwitch_InitWithTopology')
  File "/home/user/.pyenv/versions/3.9.15/lib/python3.9/site-packages/niswitch/_library.py", line 67, in _get_library_function
    raise errors.DriverTooOldError() from e
niswitch.errors.DriverTooOldError: A function was not found in the NI-SWITCH runtime. Please visit http://www.ni.com/downloads/drivers/ to download a newer version and install it.

The error is clearly misleading. I shouldn't have any issues opening a session to both devices.

I am using IVI simulated devices, so no hardware is required.
If I simulate a 4081 DMM instead of a 4071, the error doesn't happen.
If I remove the dmm.initiate() call then the error doesn't happen.
If I use Python 3.10.8 then even the reproducing example as written doesn't reproduce.
I have also rewritten the example using a simulated nidcpower.Session (using a 4190), and that DOES reproduce (so I think that nidmm must be at fault).

I have found that this is very particular, and if I modify the code slightly I can stop seeing the error (move the dmm.initiate() after opening the niswitch.Session and its fine).

System report

python -c "import nidmm; nidmm.print_diagnostic_information()" output:

OS:
    Name:      Linux
    Version:   #26~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Jul 13 16:27:29 UTC 2
    Bits:      64
Driver:
    Name:      NI-DMM
    Version:   Unknown
Module:
    Name:      nidmm
    Version:   1.4.5
Python:
    Version:   3.9.15 (main, Aug 11 2023, 09:46:20)
[GCC 11.4.0]
    Bits:      64
    Is_Venv:   False
    Installed Packages:
        virtualenv==20.24.2
        setuptools==58.1.0
        platformdirs==3.10.0
        pip==22.0.4
        niswitch==1.4.5
        nidmm==1.4.5
        nidcpower==1.4.5
        hightime==0.2.1
        filelock==3.12.2
        distlib==0.3.7
Steps to reproduce issue
import niswitch
import nidmm

with nidmm.Session(resource_name="", options= { "simulate": True, "driver_setup": { "Model": "4071" } }) as dmm_session:
    dmm_session.initiate()
    with niswitch.Session(resource_name="", topology="2535/1-Wire 4x136 Matrix", simulate=True) as session1:
        pass

Run the above code using python 3.9.15 on Linux

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the reproduced Python 3.9/Linux sequence in the issue, then inspect niswitch/_library.py, niswitch/_library_interpreter.py, and the session initialization path shown in the traceback. Compare how loading NI-DMM or NI-CPower before NI-SWITCH affects symbol lookup. Done means the reproducer can open both simulated sessions after dmm_session.initiate() without the misleading DriverTooOldError.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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