`asyncio.get_event_loop` raises error instead of spawning new loop when no loop is running.

[anonymousx97]

>>> import uvloop, asyncio
>>> asyncio.get_event_loop()
<_UnixSelectorEventLoop running=False closed=False debug=False>
>>> uvloop.install()
>>> asyncio.get_event_loop()
Traceback (most recent call last):
  File "<python-input-4>", line 1, in <module>
    asyncio.get_event_loop()
    ~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/local/lib/python3.13/site-packages/uvloop/__init__.py", line 206, in get_event_loop
    raise RuntimeError(
    ...<2 lines>...
    )
RuntimeError: There is no current event loop in thread 'MainThread'.
>>>

As you can see in the snippet above when run on un-patched asyncio it's returning a new loop. But uvloop raises error because of the method override which was not there in previous version inheriting the original new loop spawning function.

[MarSoft]

Got this issue with aiohttp.GunicornUVLoopWebWorker after updating uvloop to 0.22.1. Note that uvloop==0.21.0 does work properly, and uvloop==0.22.1 does not. For now added the following to my requirements.txt: uvloop!=0.22.1 — I hope the issue will be fixed in the next version.

[fantix]

Roger; I'm looking into this

[andylin-hao]

Same issue here. It looks like 0.22.x's EventLoopPolicy overrides its base class asyncio.events.BaseDefaultEventLoopPolicy's get_event_loop function, and removes the creating new loop behavior.

[danielbasso]

Same here; uvicorn couldn't start. The thing took a while to figure out because it started to happen without code/image changes:

Traceback (most recent call last):
  File "/usr/local/bin/uvicorn", line 7, in <module>
    sys.exit(main())
             ^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/uvicorn/main.py", line 362, in main
    run(**kwargs)
  File "/usr/local/lib/python3.11/site-packages/uvicorn/main.py", line 386, in run
    server.run()
  File "/usr/local/lib/python3.11/site-packages/uvicorn/server.py", line 48, in run
    loop = asyncio.get_event_loop()
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/uvloop/__init__.py", line 206, in get_event_loop
    raise RuntimeError(
RuntimeError: There is no current event loop in thread 'MainThread'.

[DiegoD94]

Same here, multiple project, including sglang and verl is impacted

[alex-darrow]

Same here.

mlserver[mlflow]==1.7.0 failed to start

2025-10-29 13:49:42,186 [mlserver.parallel] INFO - New worker with PID 89 on default inference pool is now ready.
Process Worker-20:
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/multiprocessing/process.py", line 314, in _bootstrap
    self.run()
  File "/usr/local/lib/python3.11/site-packages/mlserver/parallel/worker.py", line 70, in run
    self._ignore_signals()
  File "/usr/local/lib/python3.11/site-packages/mlserver/parallel/worker.py", line 81, in _ignore_signals
    loop = asyncio.get_event_loop()
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/uvloop/__init__.py", line 206, in get_event_loop
    raise RuntimeError(
RuntimeError: There is no current event loop in thread 'MainThread'.
Process Worker-19:
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/multiprocessing/process.py", line 314, in _bootstrap
    self.run()
  File "/usr/local/lib/python3.11/site-packages/mlserver/parallel/worker.py", line 70, in run
    self._ignore_signals()
  File "/usr/local/lib/python3.11/site-packages/mlserver/parallel/worker.py", line 81, in _ignore_signals
    loop = asyncio.get_event_loop()
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/uvloop/__init__.py", line 206, in get_event_loop
    raise RuntimeError(
RuntimeError: There is no current event loop in thread 'MainThread'.
Process Worker-16:

kubectl exec -n kserve 5f9885f6d9-wzg6d -- pip list | grep -E "(uvloop|mlserver)"
Defaulted container "kserve-container" out of: kserve-container, storage-initializer (init)
mlserver                                 1.7.1
mlserver-mlflow                          1.7.1
uvloop                                   0.22.1