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
460254571,MDU6SXNzdWU0NjAyNTQ1NzE=,3041,nc file locked by xarray after (double) da.compute() call,31093031,open,0,,,5,2019-06-25T07:19:35Z,2021-07-21T14:29:57Z,,NONE,,,,"Hi,
I've recently started to use dask.array to compute and load only chunks of a huge dataset for the development of [Parcels](https://github.com/OceanParcels/parcels). I've run into an issue of locked netcdf files while running multiple tests using py.test, and I think my bug should be related to the reduced issue that I reproduce hereinafter:

#### Problem Description
```
import numpy as np
import xarray as xr
import dask.array as da

def create_ds():
    temp = 15 + 8 * np.random.randn(2, 2)
    precip = 10 * np.random.rand(2, 2)
    lon = [[-99.83, -99.32], [-99.79, -99.23]]
    lat = [[42.25, 42.21], [42.63, 42.59]]
    ds = xr.Dataset({'temperature': (['x', 'y'],  temp),
                     'precipitation': (['x', 'y'], precip)},
                      coords={'lon': (['x', 'y'], lon),
                              'lat': (['x', 'y'], lat)})
    ds.to_netcdf('test.nc')

def dask_op():
    ds = xr.open_dataset('test.nc')
    temp = da.from_array(ds.temperature, chunks='auto')
    temp.compute()
    temp.compute()

create_ds()
dask_op()
dset = xr.Dataset()
dset.to_netcdf('test.nc')
```

####  Output
The last line of the mini-code crashes since `test.nc` is still locked.
Of course the problem can be circumvented by closing the dataset after last call to `temp.compute`, but this operation is not necessary if `temp.compute()` is called only once?

#### Working and not working alternatives
If I replace the 2 `temp.compute()` lines by either:
```
temp.compute()
```
or 
```
temp.compute()
temp.compute()
ds.close
```
The code passes, but with those blocks:
```
temp.compute()
temp.compute()
```
or 
```
ds.close
temp.compute()
temp.compute()
ds.close
```
it doesn't.

This issue was also posted on [dask](https://github.com/dask/dask/issues/4966), where I was advised to also ask for help here.
Any hint about the reason for this issue? Thanks!

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