Error Deleting Cache

At PyData NYC Sprints we ran into this bug using filecache.

---------------------------------------------------------------------------
PermissionError                           Traceback (most recent call last)
<ipython-input-9-d2fe724ed575> in <module>
----> 1 stocks.hvplot.line(x='Date', y='High')

c:\users\afrowell\documents\sage3iss\science\pydata2019\holoviz\hvplot\hvplot\plotting\core.py in line(self, x, y, **kwds)
    146         HoloViews object: Object representing the requested visualization
    147         """
--> 148         return self(x, y, kind='line', **kwds)
    149 
    150     def step(self, x=None, y=None, where='mid', **kwds):

c:\users\afrowell\documents\sage3iss\science\pydata2019\holoviz\hvplot\hvplot\plotting\core.py in __call__(self, x, y, kind, **kwds)
     70                 return pn.panel(plot, **panel_dict)
     71 
---> 72         return self._get_converter(x, y, kind, **kwds)(kind, x, y)
     73 
     74     def _get_converter(self, x=None, y=None, kind=None, **kwds):

c:\users\afrowell\documents\sage3iss\science\pydata2019\holoviz\hvplot\hvplot\plotting\core.py in _get_converter(self, x, y, kind, **kwds)
     78         kind = kind or params.pop('kind', None)
     79         return HoloViewsConverter(
---> 80             self._data, x, y, kind=kind, **params
     81         )
     82 

c:\users\afrowell\documents\sage3iss\science\pydata2019\holoviz\hvplot\hvplot\converter.py in __init__(self, data, x, y, kind, by, use_index, group_label, value_label, backlog, persist, use_dask, crs, fields, groupby, dynamic, grid, legend, rot, title, xlim, ylim, clim, symmetric, logx, logy, loglog, hover, subplots, label, invert, stacked, colorbar, fontsize, datashade, rasterize, row, col, figsize, debug, framewise, aggregator, projection, global_extent, geo, precompute, flip_xaxis, flip_yaxis, dynspread, hover_cols, x_sampling, y_sampling, project, tools, attr_labels, coastline, tiles, sort_date, check_symmetric_max, **kwds)
    309         self._process_data(kind, data, x, y, by, groupby, row, col,
    310                            use_dask, persist, backlog, label, value_label,
--> 311                            hover_cols, attr_labels, kwds)
    312 
    313         self.value_label = value_label

c:\users\afrowell\documents\sage3iss\science\pydata2019\holoviz\hvplot\hvplot\converter.py in _process_data(self, kind, data, x, y, by, groupby, row, col, use_dask, persist, backlog, label, value_label, hover_cols, attr_labels, kwds)
    543             data = data.to_frame()
    544         if is_intake(data):
--> 545             data = process_intake(data, use_dask or persist)
    546 
    547         if groupby is not None and not isinstance(groupby, list):

c:\users\afrowell\documents\sage3iss\science\pydata2019\holoviz\hvplot\hvplot\util.py in process_intake(data, use_dask)
    269         data = data.to_dask()
    270     else:
--> 271         data = data.read()
    272     return data
    273 

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\intake\source\csv.py in read(self)
    141     def read(self):
    142         self._get_schema()
--> 143         return self._dataframe.compute()
    144 
    145     def to_dask(self):

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\base.py in compute(self, **kwargs)
    163         dask.base.compute
    164         """
--> 165         (result,) = compute(self, traverse=False, **kwargs)
    166         return result
    167 

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\base.py in compute(*args, **kwargs)
    434     keys = [x.__dask_keys__() for x in collections]
    435     postcomputes = [x.__dask_postcompute__() for x in collections]
--> 436     results = schedule(dsk, keys, **kwargs)
    437     return repack([f(r, *a) for r, (f, a) in zip(results, postcomputes)])
    438 

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\threaded.py in get(dsk, result, cache, num_workers, pool, **kwargs)
     78         get_id=_thread_get_id,
     79         pack_exception=pack_exception,
---> 80         **kwargs
     81     )
     82 

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\local.py in get_async(apply_async, num_workers, dsk, result, cache, get_id, rerun_exceptions_locally, pack_exception, raise_exception, callbacks, dumps, loads, **kwargs)
    484                         _execute_task(task, data)  # Re-execute locally
    485                     else:
--> 486                         raise_exception(exc, tb)
    487                 res, worker_id = loads(res_info)
    488                 state["cache"][key] = res

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\local.py in reraise(exc, tb)
    314     if exc.__traceback__ is not tb:
    315         raise exc.with_traceback(tb)
--> 316     raise exc
    317 
    318 

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\local.py in execute_task(key, task_info, dumps, loads, get_id, pack_exception)
    220     try:
    221         task, data = loads(task_info)
--> 222         result = _execute_task(task, data)
    223         id = get_id()
    224         result = dumps((result, id))

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in _execute_task(arg, cache, dsk)
    117         func, args = arg[0], arg[1:]
    118         args2 = [_execute_task(a, cache) for a in args]
--> 119         return func(*args2)
    120     elif not ishashable(arg):
    121         return arg

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\optimization.py in __call__(self, *args)
    974         if not len(args) == len(self.inkeys):
    975             raise ValueError("Expected %d args, got %d" % (len(self.inkeys), len(args)))
--> 976         return core.get(self.dsk, self.outkey, dict(zip(self.inkeys, args)))
    977 
    978     def __reduce__(self):

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in get(dsk, out, cache)
    147     for key in toposort(dsk):
    148         task = dsk[key]
--> 149         result = _execute_task(task, cache)
    150         cache[key] = result
    151     result = _execute_task(out, cache)

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in _execute_task(arg, cache, dsk)
    116     elif istask(arg):
    117         func, args = arg[0], arg[1:]
--> 118         args2 = [_execute_task(a, cache) for a in args]
    119         return func(*args2)
    120     elif not ishashable(arg):

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in <listcomp>(.0)
    116     elif istask(arg):
    117         func, args = arg[0], arg[1:]
--> 118         args2 = [_execute_task(a, cache) for a in args]
    119         return func(*args2)
    120     elif not ishashable(arg):

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in _execute_task(arg, cache, dsk)
    116     elif istask(arg):
    117         func, args = arg[0], arg[1:]
--> 118         args2 = [_execute_task(a, cache) for a in args]
    119         return func(*args2)
    120     elif not ishashable(arg):

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in <listcomp>(.0)
    116     elif istask(arg):
    117         func, args = arg[0], arg[1:]
--> 118         args2 = [_execute_task(a, cache) for a in args]
    119         return func(*args2)
    120     elif not ishashable(arg):

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in _execute_task(arg, cache, dsk)
    113     """
    114     if isinstance(arg, list):
--> 115         return [_execute_task(a, cache) for a in arg]
    116     elif istask(arg):
    117         func, args = arg[0], arg[1:]

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in <listcomp>(.0)
    113     """
    114     if isinstance(arg, list):
--> 115         return [_execute_task(a, cache) for a in arg]
    116     elif istask(arg):
    117         func, args = arg[0], arg[1:]

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\core.py in _execute_task(arg, cache, dsk)
    117         func, args = arg[0], arg[1:]
    118         args2 = [_execute_task(a, cache) for a in args]
--> 119         return func(*args2)
    120     elif not ishashable(arg):
    121         return arg

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\dask\bytes\core.py in read_block_from_file(lazy_file, off, bs, delimiter)
    179 
    180 def read_block_from_file(lazy_file, off, bs, delimiter):
--> 181     with copy.copy(lazy_file) as f:
    182         if off == 0 and bs is None:
    183             return f.read()

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\core.py in __enter__(self)
     86         mode = self.mode.replace("t", "").replace("b", "") + "b"
     87 
---> 88         f = self.fs.open(self.path, mode=mode)
     89 
     90         self.fobjects = [f]

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\implementations\cached.py in <lambda>(*args, **kw)
    259             # all the methods defined in this class. Note `open` here, since
    260             # it calls `_open`, but is actually in superclass
--> 261             return lambda *args, **kw: getattr(type(self), item)(self, *args, **kw)
    262         if item == "__class__":
    263             return type(self)

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\spec.py in open(self, path, mode, block_size, **kwargs)
    706             ac = kwargs.pop("autocommit", not self._intrans)
    707             f = self._open(
--> 708                 path, mode=mode, block_size=block_size, autocommit=ac, **kwargs
    709             )
    710             if not ac:

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\implementations\cached.py in <lambda>(*args, **kw)
    259             # all the methods defined in this class. Note `open` here, since
    260             # it calls `_open`, but is actually in superclass
--> 261             return lambda *args, **kw: getattr(type(self), item)(self, *args, **kw)
    262         if item == "__class__":
    263             return type(self)

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\implementations\cached.py in _open(self, path, mode, **kwargs)
    344                 # this only applies to HTTP, should instead use streaming
    345                 f2.write(f.read())
--> 346         self.save_cache()
    347         return self._open(path, mode)

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\implementations\cached.py in <lambda>(*args, **kw)
    259             # all the methods defined in this class. Note `open` here, since
    260             # it calls `_open`, but is actually in superclass
--> 261             return lambda *args, **kw: getattr(type(self), item)(self, *args, **kw)
    262         if item == "__class__":
    263             return type(self)

c:\users\afrowell\.conda\envs\hvplotpip\lib\site-packages\fsspec\implementations\cached.py in save_cache(self)
    138         if os.path.exists(fn):
    139             os.remove(fn)
--> 140         os.rename(fn + ".temp", fn)
    141 
    142     def _check_cache(self):

PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'c:/users/afrowell/documents/sage3iss/science/pydata2019/holoviz/hvplot/hvplot/../examples//data/cache\\cache.temp' -> 'c:/users/afrowell/documents/sage3iss/science/pydata2019/holoviz/hvplot/hvplot/../examples//data/cache\\cache'

Start in fsspec/implementations/cached.py, following the save_cache path shown in the traceback and its cache.temp-to-cache rename. Reproduce the failure on Windows with the reported cache usage, then verify that cache updates no longer raise PermissionError when the file is still in use.