Visa resource manager communication errors

[pikestefan]

What is affected by this bug?

Hello, I have forked qudi in July 2020. I have found an issue when loading the microwave.mw_source_srssg.MicrowaveSRSSG class.

When does this occur?

When I load the hardware module, I get the error pasted at the end of this message. With a bit of debugging I found out that the issue occurs whenever the visa.ResourceManager() does any type of query (e.g. listing resources or connecting to a device).

How do we replicate the issue?

I managed to reproduce the error with this fake hardware module:

from core.module import Base
import visa

class testerror(Base):
    def on_activate(self):
        self.res_manager = visa.ResourceManager()
        self.res_manager.list_resources()

    def on_deactivate(self):
       pass

Error message

Windows fatal exception: access violation

Thread 0x0000330c (most recent call first):
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\parentpoller.py", line 132 in run
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 884 in _bootstrap

Thread 0x00002ba4 (most recent call first):
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\zmq\utils\garbage.py", line 47 in run
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 884 in _bootstrap

Thread 0x00002a54 (most recent call first):
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\tornado\platform\select.py", line 63 in poll
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\tornado\ioloop.py", line 863 in start
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\ipykernel\iostream.py", line 78 in _thread_main
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 864 in run
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 884 in _bootstrap

Thread 0x00000f64 (most recent call first):
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 295 in wait
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 551 in wait
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\IPython\core\history.py", line 829 in run
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\IPython\core\history.py", line 58 in needs_sqlite
  File "<decorator-gen-24>", line 2 in run
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\threading.py", line 884 in _bootstrap

Thread 0x00000c48 (most recent call first):
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\socket.py", line 205 in accept
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\rpyc\utils\server.py", line 139 in accept
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\rpyc\utils\server.py", line 263 in start
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\remote.py", line 252 in run

Current thread 0x00000358 (most recent call first):
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\pyvisa\ctwrapper\functions.py", line 485 in find_resources
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\pyvisa\ctwrapper\highlevel.py", line 205 in list_resources
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\pyvisa\highlevel.py", line 1571 in list_resources
  File "C:\Users\QMPL\Documents\GitHub\qudi\hardware\microwave\test_errors.py", line 14 in on_activate
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\module.py", line 223 in __load_status_vars_activate
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\fysom\__init__.py", line 95 in _callback
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\fysom\__init__.py", line 338 in _after_event
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\fysom\__init__.py", line 306 in _tran
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\site-packages\fysom\__init__.py", line 311 in fn
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\module.py", line 98 in wrap_event
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\manager.py", line 969 in activateModule
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\manager.py", line 1172 in startModule
  File "C:\Users\QMPL\Documents\GitHub\qudi\gui\manager\managergui.py", line 622 in loadButtonClicked
  File "C:\Users\QMPL\Documents\GitHub\qudi\core\__main__.py", line 311 in <module>
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\runpy.py", line 85 in _run_code
  File "C:\Users\QMPL\Anaconda3\envs\qudi\lib\runpy.py", line 193 in _run_module_as_main

[Neverhorst]

Hi @pikestefan. Your example illustrates that your issue has nothing to do with qudi itself. Apparently your pyvisa package installation or the used system visa binary installation is somehow broken. I bet you can reproduce the same problem just running the code in the same Python environment (without qudi).

[pikestefan]

Hi @Neverhorst, Do you mean I should get the same error when trying to use the resource manager within the qudi environment? I gave it a quick try in the anaconda prompt, but nothing looks amiss there.

[Neverhorst]

Ok, that's very strange. If you are absolutely sure you are using the same conda environment for both tests I'm at a loss. qudi does not alter pyvisa in any way. The only thing that could have an effect are paths that are inserted at the beginning of sys.path during qudi startup. But I do not suspect this to break visa. I mean the pyvisa package is used in most qudi hardware modules so far... A last resort that comes to my mind is to re-install the system VISA library (e.g. from NI, Keysight, etc.) and the qudi conda environment. Just in case something got mixed up there. (would not be the first time for conda and binary bindings).

[pikestefan]

Thanks a lot for your reply! It turns out the problem was indeed the VISA library itself: after uninstalling and reinstalling the distribution, the error stopped popping up.

[Neverhorst]

Glad everything worked out.