Likely libusb fault on Windows 10

[buzmeg]

Tried to install pyocd on Windows 10 today:

(venv) C:\Users\andrewl\Desktop\python\pyocdvenv\pyOCD>pyocd list
Exception ignored in: <function _AutoFinalizedObjectBase.__del__ at 0x000002DF16228AF0>
Traceback (most recent call last):
  File "C:\Users\andrewl\Desktop\python\pyocdvenv\venv\lib\site-packages\usb\_objfinalizer.py", line 84, in __del__
    self.finalize()
  File "C:\Users\andrewl\Desktop\python\pyocdvenv\venv\lib\site-packages\usb\_objfinalizer.py", line 144, in finalize
    self._finalizer()
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.8_3.8.1008.0_x64__qbz5n2kfra8p0\lib\weakref.py", line 566, in __call__
    return info.func(*info.args, **(info.kwargs or {}))
  File "C:\Users\andrewl\Desktop\python\pyocdvenv\venv\lib\site-packages\usb\_objfinalizer.py", line 104, in _do_finalize_object_ref
    obj._do_finalize_object()
  File "C:\Users\andrewl\Desktop\python\pyocdvenv\venv\lib\site-packages\usb\_objfinalizer.py", line 71, in _do_finalize_object
    self._finalize_object()
  File "C:\Users\andrewl\Desktop\python\pyocdvenv\venv\lib\site-packages\usb\backend\libusb1.py", line 604, in _finalize_object
    _lib.libusb_unref_device(self.devid)
OSError: exception: access violation writing 0x0000000000000024
  #   Probe                                               Unique ID
---------------------------------------------------------------------
  0   Thirdwayv DAPB Thirdwayv Bulk CMSIS-DAP Interface   AAAAAAAA

Presumably the fact that you're ignoring it means that you have seen it before. I believe that this is a libusb bug and it's biting a lot of people in other projects as well.

[tdjastrzebski]

I experience a similar issue with version 0.27.2 on Windows 10

C:\Users\Thomas>pyocd list
  #   Probe       Unique ID
--------------------------------------------
  0   STLINK-V3   003000363137510D33333639
Exception ignored in: <bound method _AutoFinalizedObjectBase.__del__ of <usb.backend.libusb1._Device object at 0x000002A2C8CDE780>>
Traceback (most recent call last):
  File "C:\Users\Thomas\AppData\Roaming\Python\Python36\site-packages\usb\_objfinalizer.py", line 84, in __del__
    self.finalize()
  File "C:\Users\Thomas\AppData\Roaming\Python\Python36\site-packages\usb\_objfinalizer.py", line 144, in finalize
    self._finalizer()
  File "c:\program files\python36\lib\weakref.py", line 548, in __call__
    return info.func(*info.args, **(info.kwargs or {}))
  File "C:\Users\Thomas\AppData\Roaming\Python\Python36\site-packages\usb\_objfinalizer.py", line 104, in _do_finalize_object_ref
    obj._do_finalize_object()
  File "C:\Users\Thomas\AppData\Roaming\Python\Python36\site-packages\usb\_objfinalizer.py", line 71, in _do_finalize_object
    self._finalize_object()
  File "C:\Users\Thomas\AppData\Roaming\Python\Python36\site-packages\usb\backend\libusb1.py", line 604, in _finalize_object
    _lib.libusb_unref_device(self.devid)
OSError: exception: access violation writing 0x0000000000000024

[flit]

This should be addressed now. The problem was a long-standing bug in the pyusb package that surfaced after libusb changed something related to allocation management. pyusb 1.1.0 was recently released that should fix it. (Frustratingly, the fix was available in the pyusb repo for a long time, but never released until recently due to maintainership issues.)

[tdjastrzebski]

@flit thank you, so the fix will be available in the next release?

[flit]

The fix (and bug) was in pyusb, not pyocd. So if you run pip install -U pyusb it will update to the latest pyusb 1.1.0 that has the fix.

Fwiw, you can instead run pip install -U --upgrade-strategy=eager pyocd to update all pyocd's dependencies to the latest versions.

[tdjastrzebski]

@flit I confirm it helped, the issue appears to be fixed

[flit]

Excellent, thanks for confirming it works on your system!