JSONDecodeError when checking for upgrades

[staticf0x]

Description

Running pipupgrade -c -l -u --pip-path ~/.local/bin/pip3 and I got this error:

"""
Traceback (most recent call last):
  File "/usr/lib64/python3.10/concurrent/futures/process.py", line 246, in _process_worker
    r = call_item.fn(*call_item.args, **call_item.kwargs)
  File "/usr/lib64/python3.10/concurrent/futures/process.py", line 205, in _process_chunk
    return [fn(*args) for args in chunk]
  File "/usr/lib64/python3.10/concurrent/futures/process.py", line 205, in <listcomp>
    return [fn(*args) for args in chunk]
  File "/home/asdf/.local/lib/python3.10/site-packages/pipupgrade/commands/helper.py", line 322, in get_registry_from_pip
    packages     = json.loads(output)
  File "/usr/lib64/python3.10/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib64/python3.10/json/decoder.py", line 340, in decode
    raise JSONDecodeError("Extra data", s, end)
json.decoder.JSONDecodeError: Extra data: line 3 column 1 (char 2354)
"""

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

Traceback (most recent call last):
  File "/home/asdf/.local/lib/python3.10/site-packages/pipupgrade/commands/__init__.py", line 79, in command
    return _command(**ARGUMENTS)
  File "/home/asdf/.local/lib/python3.10/site-packages/pipupgrade/commands/__init__.py", line 240, in _command
    for registry in pool.imap_unordered(
  File "/usr/lib64/python3.10/concurrent/futures/process.py", line 570, in _chain_from_iterable_of_lists
    for element in iterable:
  File "/usr/lib64/python3.10/concurrent/futures/_base.py", line 609, in result_iterator
    yield fs.pop().result()
  File "/usr/lib64/python3.10/concurrent/futures/_base.py", line 446, in result
    return self.__get_result()
  File "/usr/lib64/python3.10/concurrent/futures/_base.py", line 391, in __get_result
    raise self._exception
json.decoder.JSONDecodeError: Extra data: line 3 column 1 (char 2354)```

Tried deleting the contents of `~/.config/pipupgrade` but that didn't do anything.

### Screenshot

_No response_

### Console errors

_No response_

[bonkey]

I experienced the same. I found out that running:

/opt/homebrew/bin/pip list --outdated --format json

returned

[{"name": "pip", "version": "22.1.2", "latest_version": "22.2", "latest_filetype": "wheel"}]
[notice] A new release of pip available: 22.1.2 -> 22.2
[notice] To update, run: python3.9 -m pip install --upgrade pip

So, I did run python3.9 -m pip install --upgrade pip and no more errors, but I guess only because /opt/homebrew/bin/pip list --outdated --format json returns empty array ([]).

Perhaps the issue is with extra notice text:

[notice] A new release of pip available: 22.1.2 -> 22.2
[notice] To update, run: python3.9 -m pip install --upgrade pip

Which is not parseable JSON but is presented on stdout?

[staticf0x]

Hah gotcha thanks @bonkey, upgrading pip solved it. It's exactly as you mentioned, pip 22.1.2 produces

[notice] A new release of pip available: 22.1.2 -> 22.2
[notice] To update, run: pip install --upgrade pip

so upgrading pip to the latest version (22.2) fixes that. You can get rid of the notice by adding --disable-pip-version-check, then the JSON is parseable (tried in iPython). There is a related bug opened in the pip repository: pypa/pip#10881 but if my tests are correct, in pipupgrade it could be solved just by adding the --disable-pip-version-check flag.

[staticf0x]

The place to start would be here:

pipupgrade/src/pipupgrade/commands/helper.py

Line 319 in 8260e49

_, output, _ = _pip.call("list", user = user, outdated = outdated, \

I think

If I have some time this week I can investigate it a bit more.