TypeError: cannot pickle 'itertools.count' object on Fedora 43 with Python 3.14

[hpaluch-pil]

On latest stable Fedora 43 with Python 3.14 (and 2 other workarounds applied - see below) I get fatal error when running trivial example:

$ avocado run --vt-guest-os Guest.Linux.JeOS.27.x86_64  type_specific.io-github-autotest-qemu.hello_world  
JOB ID     : a5b8286439a60a739c1363249b97be9fbea0b47d                                                                             
JOB LOG    : /home/ansible/avocado/job-results/job-2025-11-18T08.37-a5b8286/job.log                                               
 (1/1) type_specific.io-github-autotest-qemu.hello_world: STARTED                                                                 
 (1/1) type_specific.io-github-autotest-qemu.hello_world:  ERROR: cannot pickle 'itertools.count' object (16.04 s)                
RESULTS    : PASS 0 | ERROR 1 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0                                                 
JOB TIME   : 16.90 s                                                     

Full error details from ~/avocado/job-results/latest/test-results/1-type_specific.io-github-autotest-qemu.hello_ world/stderr:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 140, in _safe_env_save
    env.save()
    ~~~~~~~~^^
  File "/usr/lib/python3.14/site-packages/virttest/utils_env.py", line 108, in save
    cPickle.dump(self.data, f, protocol=0)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/copyreg.py", line 75, in _reduce_ex
    raise TypeError(f"cannot pickle {cls.__name__!r} object")
TypeError: cannot pickle 'count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 143, in _safe_env_save
    pickle.dumps(env.data)
    ~~~~~~~~~~~~^^^^^^^^^^
TypeError: cannot pickle 'itertools.count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/test.py", line 284, in _runTest
    self._safe_env_save(env)
    ~~~~~~~~~~~~~~~~~~~^^^^^
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 147, in _safe_env_save
    stacktrace.str_unpickable_object(env.data),
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/usr/lib/python3.14/site-packages/avocado/utils/stacktrace.py", line 115, in str_unpickable_object
    pickle.dumps(obj)
    ~~~~~~~~~~~~^^^^^
TypeError: cannot pickle 'itertools.count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 140, in _safe_env_save
    env.save()
    ~~~~~~~~^^
  File "/usr/lib/python3.14/site-packages/virttest/utils_env.py", line 108, in save
    cPickle.dump(self.data, f, protocol=0)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/copyreg.py", line 75, in _reduce_ex
    raise TypeError(f"cannot pickle {cls.__name__!r} object")
TypeError: cannot pickle 'count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 143, in _safe_env_save
    pickle.dumps(env.data)
    ~~~~~~~~~~~~^^^^^^^^^^
TypeError: cannot pickle 'itertools.count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/test.py", line 314, in _runTest
    self._safe_env_save(env)
    ~~~~~~~~~~~~~~~~~~~^^^^^
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 147, in _safe_env_save
    stacktrace.str_unpickable_object(env.data),
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/usr/lib/python3.14/site-packages/avocado/utils/stacktrace.py", line 115, in str_unpickable_object
    pickle.dumps(obj)
    ~~~~~~~~~~~~^^^^^
TypeError: cannot pickle 'itertools.count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 140, in _safe_env_save
    env.save()
    ~~~~~~~~^^
  File "/usr/lib/python3.14/site-packages/virttest/utils_env.py", line 108, in save
    cPickle.dump(self.data, f, protocol=0)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/copyreg.py", line 75, in _reduce_ex
    raise TypeError(f"cannot pickle {cls.__name__!r} object")
TypeError: cannot pickle 'count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 143, in _safe_env_save
    pickle.dumps(env.data)
    ~~~~~~~~~~~~^^^^^^^^^^
TypeError: cannot pickle 'itertools.count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.14/site-packages/avocado_vt/plugins/vt_runner.py", line 74, in runTest
    raise self.__status  # pylint: disable-msg=E0702
    ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.14/site-packages/avocado_vt/test.py", line 146, in setUp
    self._runTest()
    ~~~~~~~~~~~~~^^
  File "/usr/lib/python3.14/site-packages/avocado_vt/test.py", line 338, in _runTest
    self._safe_env_save(env)
    ~~~~~~~~~~~~~~~~~~~^^^^^
  File "/usr/lib/python3.14/site-packages/avocado_vt/utils.py", line 147, in _safe_env_save
    stacktrace.str_unpickable_object(env.data),
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/usr/lib/python3.14/site-packages/avocado/utils/stacktrace.py", line 115, in str_unpickable_object
    pickle.dumps(obj)
    ~~~~~~~~~~~~^^^^^
TypeError: cannot pickle 'itertools.count' object
when serializing dict item '_index'
when serializing virttest.vt_iothread.PredefinedManager state
when serializing virttest.vt_iothread.PredefinedManager object
when serializing dict item '_DevContainer__iothread_manager'
when serializing virttest.qemu_devices.qcontainer.DevContainer state
when serializing virttest.qemu_devices.qcontainer.DevContainer object
when serializing dict item 'devices'
when serializing virttest.qemu_vm.VM state
when serializing virttest.qemu_vm.VM object
when serializing dict item 'vm__avocado-vt-vm1'

Environment details:

$ cat /etc/fedora-release 

Fedora release 43 (Forty Three)

$ rpm -q python3 python3-avocado-plugins-vt python3-aexpect

python3-3.14.0-2.fc43.x86_64
python3-avocado-plugins-vt-109.0-1.20251118gita8ce8469.fc43.noarch
python3-aexpect-1.6.2-18.fc43.noarch

More details:

• using COPR distribution with sudo dnf copr enable @avocado/avocado-vt-latest
• applied fix for broken aexpect (incompatible with python 3.14): Drop the use of pipes aexpect#128 - reported to RedHat on https://bugzilla.redhat.com/show_bug.cgi?id=2414808 but maintainer is not responding
• applied avocado-vt fix for python 3.14: Fix multiprocessing compatibility for Python 3.14 #4244

[hpaluch-pil]

Possibly caused by:

• deprecated on: Deprecate pickle support for itertools python/cpython#101588
• removed on (Python 3.14): GH-101588: Remove deprecated pickle/copy/deepcopy from itertools python/cpython#118816