uproot.daskframe Too many open files error

Traceback (most recent call last):
  File "daskframe_from_rootfile.py", line 38, in <module>
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/base.py", line 165, in compute
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/base.py", line 436, in compute
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/threaded.py", line 81, in get
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/local.py", line 486, in get_async
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/local.py", line 316, in reraise
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/local.py", line 222, in execute_task
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/core.py", line 118, in _execute_task
    args2 = [_execute_task(a, cache) for a in args]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/core.py", line 118, in <listcomp>
    args2 = [_execute_task(a, cache) for a in args]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/core.py", line 118, in _execute_task
    args2 = [_execute_task(a, cache) for a in args]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/core.py", line 118, in <listcomp>
    args2 = [_execute_task(a, cache) for a in args]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/core.py", line 119, in _execute_task
    return func(*args2)
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/dask/array/core.py", line 104, in getter
    c = a[b]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/awkward/array/chunked.py", line 428, in __getitem__
    chunk = self._chunks[chunkid][(slice(local_start, local_stop, step),)]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/awkward/array/virtual.py", line 369, in __getitem__
    return self.array[where]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/awkward/array/virtual.py", line 295, in array
    return self.materialize()
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/awkward/array/virtual.py", line 326, in materialize
    array = self._util_toarray(self._generator(*self._args, **self._kwargs), self.DEFAULTTYPE)
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/uproot/tree.py", line 1873, in __call__
    tree = self.trees[self.paths[pathi]] = uproot.rootio.open(self.paths[pathi])[self.treepath]
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/uproot/rootio.py", line 54, in open
    return ROOTDirectory.read(openfcn(path), **options)
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/uproot/rootio.py", line 51, in <lambda>
    openfcn = lambda path: MemmapSource(path, **kwargs)
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/uproot/source/memmap.py", line 21, in __init__
    self._source = numpy.memmap(self.path, dtype=numpy.uint8, mode="r")
  File "/gpfs/share/home/meliache/envs/analysistools/lib/python3.6/site-packages/numpy/core/memmap.py", line 264, in __new__
    mm = mmap.mmap(fid.fileno(), bytes, access=acc, offset=start)
OSError: [Errno 24] Too many open files