DispatcherMiddleware throws LifespanTimeoutError

[danielniccoli]

When using the DispatcherMiddleware with two ASGI-Lifespan capable app, it throws a LifespanTimeoutError. When running each of the apps individually without the dispatcher, ASGI-Lifespan is active and working. This leads me to believe that there may be an issue with the DispatcherMiddleware.

The complete traceback is:

  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/asyncio/tasks.py", line 507, in wait_for
    return await fut
           ^^^^^^^^^
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/asyncio/locks.py", line 213, in wait
    await fut
asyncio.exceptions.CancelledError

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

Traceback (most recent call last):
  File "/code/hypercornlitestarissue/.venv/lib/python3.13/site-packages/hypercorn/asyncio/lifespan.py", line 94, in wait_for_startup
    await asyncio.wait_for(self.startup.wait(), timeout=self.config.startup_timeout)
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/asyncio/tasks.py", line 506, in wait_for
    async with timeouts.timeout(timeout):
               ~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/asyncio/timeouts.py", line 116, in __aexit__
    raise TimeoutError from exc_val
TimeoutError

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

Traceback (most recent call last):
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/multiprocessing/process.py", line 313, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/code/hypercornlitestarissue/.venv/lib/python3.13/site-packages/hypercorn/asyncio/run.py", line 196, in asyncio_worker
    _run(
    ~~~~^
        partial(worker_serve, app, config, sockets=sockets),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        debug=config.debug,
        ^^^^^^^^^^^^^^^^^^^
        shutdown_trigger=shutdown_trigger,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/code/hypercornlitestarissue/.venv/lib/python3.13/site-packages/hypercorn/asyncio/run.py", line 234, in _run
    runner.run(main(shutdown_trigger=shutdown_trigger))
    ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/root/.local/share/uv/python/cpython-3.13.6-linux-x86_64-gnu/lib/python3.13/asyncio/base_events.py", line 725, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/code/hypercornlitestarissue/.venv/lib/python3.13/site-packages/hypercorn/asyncio/run.py", line 84, in worker_serve
    await lifespan.wait_for_startup()
  File "/code/hypercornlitestarissue/.venv/lib/python3.13/site-packages/hypercorn/asyncio/lifespan.py", line 96, in wait_for_startup
    raise LifespanTimeoutError("startup") from error
hypercorn.utils.LifespanTimeoutError: Timeout whilst awaiting startup. Your application may not support the ASGI Lifespan protocol correctly, alternatively the startup_timeout configuration is incorrect.

You can find a reproducible project here: https://github.com/danielniccoli/hypercornlitestarissue