Faster message serialization

[fleming79]

This PR provides faster pack and unpack defaults by utilizing orjson a "fast, correct JSON library".

Support is also added for msgpack.

New functions

• orjson_packer
• orjson_unpacker
• msgpack_packer
• msgpack_unpacker

Performance comparison

Code

import datetime
from jupyter_client import session
msg = {'header': {'msg_id': '7bd90b92-3625dcab810fadd2f13d2c53_139086_1',
  'msg_type': 'msg',
  'username': 'username',
  'session': '7bd90b92-3625dcab810fadd2f13d2c53',
  'date': datetime.datetime(2025, 6, 9, 3, 46, 52, 133647, tzinfo=datetime.timezone.utc),
  'version': '5.3'},
 'msg_id': '7bd90b92-3625dcab810fadd2f13d2c53_139086_1',
 'msg_type': 'msg',
 'parent_header': {'msg_id': '7bd90b92-3625dcab810fadd2f13d2c53_139086_0',
  'msg_type': 'msg',
  'username': 'username',
  'session': '7bd90b92-3625dcab810fadd2f13d2c53',
  'date': datetime.datetime(2025, 6, 9, 3, 46, 52, 133525, tzinfo=datetime.timezone.utc),
  'version': '5.3'},
 'content': {'t': datetime.datetime(2025, 6, 9, 3, 46, 52, 133280, tzinfo=datetime.timezone.utc)},
 'metadata': {'t': datetime.datetime(2025, 6, 9, 3, 46, 52, 133305, tzinfo=datetime.timezone.utc)}}


%timeit session.orjson_packer(msg)

%timeit session.json_packer(msg)

%timeit session.msgpack_packer(msg)

%timeit session.pickle_packer(msg)

packed = session.orjson_packer(msg)

%timeit session.orjson_unpacker(packed)

%timeit session.json_unpacker(packed)

packed = session.msgpack_packer(msg)
%timeit session.msgpack_unpacker(packed)

packed = session.pickle_packer(msg)
%timeit session.pickle_unpacker(packed)

[fleming79]

The failing tests on Windows appear to be unrelated to this PR:

I've run both the main branch and this PR on Windows locally and observe similar errors related to "unclosed sockets".

If the test is run individually it passes but when running in groups the error can move around, though generally the reported error is the same.

c:\code\jupyter_client\tests\test_multikernelmanager.py::TestKernelManager::test_start_parallel_thread_kernels failed: cls = <class '_pytest.runner.CallInfo'>
func = <function call_and_report.<locals>.<lambda> at 0x0000013B0182FB00>
when = 'call'
reraise = (<class '_pytest.outcomes.Exit'>, <class 'KeyboardInterrupt'>)

    @classmethod
    def from_call(
        cls,
        func: Callable[[], TResult],
        when: Literal["collect", "setup", "call", "teardown"],
        reraise: Optional[
            Union[Type[BaseException], Tuple[Type[BaseException], ...]]
        ] = None,
    ) -> "CallInfo[TResult]":
        """Call func, wrapping the result in a CallInfo.
    
        :param func:
            The function to call. Called without arguments.
        :param when:
            The phase in which the function is called.
        :param reraise:
            Exception or exceptions that shall propagate if raised by the
            function, instead of being wrapped in the CallInfo.
        """
        excinfo = None
        start = timing.time()
        precise_start = timing.perf_counter()
        try:
>           result: Optional[TResult] = func()

cls        = <class '_pytest.runner.CallInfo'>
duration   = 0.7103413999939221
excinfo    = <ExceptionInfo PytestUnraisableExceptionWarning('Exception ignored in: <socket.socket fd=-1, family=2, type=1, proto=0...et.socket fd=2124, family=2, type=1, proto=0, laddr=(\'127.0.0.1\', 59458), raddr=(\'127.0.0.1\', 59459)>\n') tblen=11>
func       = <function call_and_report.<locals>.<lambda> at 0x0000013B0182FB00>
precise_start = 60518.1109472
precise_stop = 60518.8212886
reraise    = (<class '_pytest.outcomes.Exit'>, <class 'KeyboardInterrupt'>)
result     = None
start      = 1749603690.353999
stop       = 1749603691.0643415
when       = 'call'

c:\code\jupyter_client\.venv\Lib\site-packages\_pytest\runner.py:340: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
c:\code\jupyter_client\.venv\Lib\site-packages\_pytest\runner.py:240: in <lambda>
    lambda: runtest_hook(item=item, **kwds), when=when, reraise=reraise
        item       = <TestCaseFunction test_start_parallel_thread_kernels>
        kwds       = {}
        runtest_hook = <HookCaller 'pytest_runtest_call'>
c:\code\jupyter_client\.venv\Lib\site-packages\pluggy\_hooks.py:512: in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
        firstresult = False
        kwargs     = {'item': <TestCaseFunction test_start_parallel_thread_kernels>}
        self       = <HookCaller 'pytest_runtest_call'>
c:\code\jupyter_client\.venv\Lib\site-packages\pluggy\_manager.py:120: in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
        firstresult = False
        hook_name  = 'pytest_runtest_call'
        kwargs     = {'item': <TestCaseFunction test_start_parallel_thread_kernels>}
        methods    = [<HookImpl plugin_name='runner', plugin=<module '_pytest.runner' from 'c:\\code\\jupyter_client\\.venv\\Lib\\site-pack...nraisableexception' from 'c:\\code\\jupyter_client\\.venv\\Lib\\site-packages\\_pytest\\unraisableexception.py'>>, ...]
        self       = <_pytest.config.PytestPluginManager object at 0x0000013B7AD034D0>
c:\code\jupyter_client\.venv\Lib\site-packages\_pytest\threadexception.py:87: in pytest_runtest_call
    yield from thread_exception_runtest_hook()
c:\code\jupyter_client\.venv\Lib\site-packages\_pytest\threadexception.py:63: in thread_exception_runtest_hook
    yield
        cm         = <_pytest.threadexception.catch_threading_exception object at 0x0000013B018048F0>
c:\code\jupyter_client\.venv\Lib\site-packages\_pytest\unraisableexception.py:90: in pytest_runtest_call
    yield from unraisable_exception_runtest_hook()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    def unraisable_exception_runtest_hook() -> Generator[None, None, None]:
        with catch_unraisable_exception() as cm:
            try:
                yield
            finally:
                if cm.unraisable:
                    if cm.unraisable.err_msg is not None:
                        err_msg = cm.unraisable.err_msg
                    else:
                        err_msg = "Exception ignored in"
                    msg = f"{err_msg}: {cm.unraisable.object!r}\n\n"
                    msg += "".join(
                        traceback.format_exception(
                            cm.unraisable.exc_type,
                            cm.unraisable.exc_value,
                            cm.unraisable.exc_traceback,
                        )
                    )
>                   warnings.warn(pytest.PytestUnraisableExceptionWarning(msg))
E                   pytest.PytestUnraisableExceptionWarning: Exception ignored in: <socket.socket fd=-1, family=2, type=1, proto=0>
E                   
E                   Traceback (most recent call last):
E                     File "c:\code\jupyter_client\.venv\Lib\site-packages\traitlets\traitlets.py", line 632, in get
E                       value = obj._trait_values[self.name]
E                               ~~~~~~~~~~~~~~~~~^^^^^^^^^^^
E                   KeyError: 'kernel_spec_manager'
E                   
E                   During handling of the above exception, another exception occurred:
E                   
E                   Traceback (most recent call last):
E                     File "c:\code\jupyter_client\.venv\Lib\site-packages\traitlets\config\configurable.py", line 179, in _load_config
E                       with self.hold_trait_notifications():
E                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
E                   ResourceWarning: unclosed <socket.socket fd=2124, family=2, type=1, proto=0, laddr=('127.0.0.1', 59458), raddr=('127.0.0.1', 59459)>

cm         = <_pytest.unraisableexception.catch_unraisable_exception object at 0x0000013B018055B0>
err_msg    = 'Exception ignored in'
msg        = 'Exception ignored in: <socket.socket fd=-1, family=2, type=1, proto=0>\n\nTraceback (most recent call last):\n  File ...losed <socket.socket fd=2124, family=2, type=1, proto=0, laddr=(\'127.0.0.1\', 59458), raddr=(\'127.0.0.1\', 59459)>\n'

c:\code\jupyter_client\.venv\Lib\site-packages\_pytest\unraisableexception.py:80: PytestUnraisableExceptionWarning

[minrk]

I've almost got the CI back into a healthy state in #1076 then I'll come back here. I think this looks great!