id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
1115878145,I_kwDOAMm_X85CgvMB,6198,[Bug]: Off-main-thread import fails,266544,closed,0,,,1,2022-01-27T07:45:02Z,2022-01-27T17:14:54Z,2022-01-27T17:14:54Z,NONE,,,,"### What happened?

Initial import of xarray fails if it happens in a non-main thread.


### What did you expect to happen?

Import succeeding on any thread

### Minimal Complete Verifiable Example

```python
import threading
def import_xarray():
    import xarray
thread = threading.Thread(target=import_xarray)
thread.start()
thread.join()
# -> RuntimeError: There is no current event loop in thread 'Thread-1'.
```


### Relevant log output

```
  File ""/opt/conda/lib/python3.9/site-packages/xarray/__init__.py"", line 1, in <module>
    from . import testing, tutorial, ufuncs
  File ""/opt/conda/lib/python3.9/site-packages/xarray/tutorial.py"", line 13, in <module>
    from .backends.api import open_dataset as _open_dataset
  File ""/opt/conda/lib/python3.9/site-packages/xarray/backends/__init__.py"", line 6, in <module>
    from .cfgrib_ import CfGribDataStore
  File ""/opt/conda/lib/python3.9/site-packages/xarray/backends/cfgrib_.py"", line 16, in <module>
    from .locks import SerializableLock, ensure_lock
  File ""/opt/conda/lib/python3.9/site-packages/xarray/backends/locks.py"", line 13, in <module>
    from dask.distributed import Lock as DistributedLock
  File ""/opt/conda/lib/python3.9/site-packages/dask/distributed.py"", line 11, in <module>
    from distributed import *
  File ""/opt/conda/lib/python3.9/site-packages/distributed/__init__.py"", line 7, in <module>
    from .actor import Actor, ActorFuture
  File ""/opt/conda/lib/python3.9/site-packages/distributed/actor.py"", line 5, in <module>
    from .client import Future
  File ""/opt/conda/lib/python3.9/site-packages/distributed/client.py"", line 59, in <module>
    from .batched import BatchedSend
  File ""/opt/conda/lib/python3.9/site-packages/distributed/batched.py"", line 10, in <module>
    from .core import CommClosedError
  File ""/opt/conda/lib/python3.9/site-packages/distributed/core.py"", line 28, in <module>
    from .comm import (
  File ""/opt/conda/lib/python3.9/site-packages/distributed/comm/__init__.py"", line 25, in <module>
    _register_transports()
  File ""/opt/conda/lib/python3.9/site-packages/distributed/comm/__init__.py"", line 17, in _register_transports
    from . import inproc, tcp, ws
  File ""/opt/conda/lib/python3.9/site-packages/distributed/comm/tcp.py"", line 387, in <module>
    class BaseTCPConnector(Connector, RequireEncryptionMixin):
  File ""/opt/conda/lib/python3.9/site-packages/distributed/comm/tcp.py"", line 389, in BaseTCPConnector
    _resolver = netutil.ExecutorResolver(close_executor=False, executor=_executor)
  File ""/opt/conda/lib/python3.9/site-packages/tornado/util.py"", line 288, in __new__
    instance.initialize(*args, **init_kwargs)
  File ""/opt/conda/lib/python3.9/site-packages/tornado/netutil.py"", line 427, in initialize
    self.io_loop = IOLoop.current()
  File ""/opt/conda/lib/python3.9/site-packages/tornado/ioloop.py"", line 263, in current
    loop = asyncio.get_event_loop()
  File ""/opt/conda/lib/python3.9/asyncio/events.py"", line 642, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'ThreadPoolExecutor-0_0'.
```


### Anything else we need to know?

This happens with version 0.20.2 from conda-forge. It does not happen with version 0.17.0 that I run locally. This may be related to a change in xarray's dependencies rather than xarray itself.

 (I see **dask**, **distributed**, **tornado**, **asyncio** in the stack trace, but it's impossible for me to decide which of these are ""at fault"").

### Environment

Failing environment is a fresh Docker image with xarray installed from conda-forge.

A previous non-failing Docker image was built in December. I don't have this image anymore, so I can't check versions there.","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/6198/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue