Issues with notebook execution on OSX (too many open files)

Edit: this is the upstream issue jupyter/nbclient#58 The current quick fix is to downgrade to nbclient v0.2

---

Describe the bug

A book I’ve successfully built many times started failing to build in the past few days without my changing the source files.

To Reproduce

Steps to reproduce the behavior:

1. Clone the book from this repo.
2. Install the latest jupyter-book from pip install jupyter-book.
3. Run jupyter-book build .
4. See error below.

  File "/anaconda3/lib/python3.7/selectors.py", line 511, in __init__
OSError: [Errno 24] Too many open files
Traceback (most recent call last):
  File "/anaconda3/lib/python3.7/site-packages/jupyter_book/sphinx.py", line 224, in build_sphinx
  File "/anaconda3/lib/python3.7/site-packages/sphinx/application.py", line 349, in build
  File "/anaconda3/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 299, in build_update
  File "/anaconda3/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 311, in build
  File "/anaconda3/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 418, in read
  File "/anaconda3/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 439, in _read_serial
  File "/anaconda3/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 479, in read_doc
  File "/anaconda3/lib/python3.7/site-packages/sphinx/io.py", line 316, in read_doc
  File "/anaconda3/lib/python3.7/site-packages/docutils/core.py", line 217, in publish
  File "/anaconda3/lib/python3.7/site-packages/sphinx/io.py", line 130, in read
  File "/anaconda3/lib/python3.7/site-packages/docutils/readers/__init__.py", line 77, in parse
  File "/anaconda3/lib/python3.7/site-packages/myst_nb/parser.py", line 65, in parse
  File "/anaconda3/lib/python3.7/site-packages/myst_nb/cache.py", line 147, in add_notebook_outputs
  File "/anaconda3/lib/python3.7/site-packages/nbclient/client.py", line 878, in execute
  File "/anaconda3/lib/python3.7/site-packages/nbclient/util.py", line 37, in wrapped
  File "/anaconda3/lib/python3.7/asyncio/base_events.py", line 584, in run_until_complete
  File "/anaconda3/lib/python3.7/site-packages/nbclient/client.py", line 474, in async_execute
  File "/anaconda3/lib/python3.7/site-packages/async_generator/_util.py", line 34, in __aenter__
  File "/anaconda3/lib/python3.7/site-packages/nbclient/client.py", line 443, in async_setup_kernel
  File "/anaconda3/lib/python3.7/site-packages/nbclient/client.py", line 396, in async_start_new_kernel_client
  File "/anaconda3/lib/python3.7/site-packages/jupyter_client/client.py", line 116, in start_channels
  File "/anaconda3/lib/python3.7/site-packages/jupyter_client/asynchronous/client.py", line 97, in hb_channel
  File "/anaconda3/lib/python3.7/asyncio/events.py", line 762, in new_event_loop
  File "/anaconda3/lib/python3.7/asyncio/events.py", line 660, in new_event_loop
  File "/anaconda3/lib/python3.7/asyncio/unix_events.py", line 51, in __init__
  File "/anaconda3/lib/python3.7/asyncio/selector_events.py", line 52, in __init__
  File "/anaconda3/lib/python3.7/selectors.py", line 511, in __init__
OSError: [Errno 24] Too many open files

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/anaconda3/bin/jupyter-book", line 8, in <module>
  File "/anaconda3/lib/python3.7/site-packages/click/core.py", line 764, in __call__
  File "/anaconda3/lib/python3.7/site-packages/click/core.py", line 717, in main
  File "/anaconda3/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
  File "/anaconda3/lib/python3.7/site-packages/click/core.py", line 956, in invoke
  File "/anaconda3/lib/python3.7/site-packages/click/core.py", line 555, in invoke
  File "/anaconda3/lib/python3.7/site-packages/jupyter_book/commands/__init__.py", line 123, in build
  File "/anaconda3/lib/python3.7/site-packages/jupyter_book/sphinx.py", line 256, in build_sphinx
  File "/anaconda3/lib/python3.7/site-packages/sphinx/cmd/build.py", line 69, in handle_exception
  File "/anaconda3/lib/python3.7/site-packages/sphinx/util/__init__.py", line 255, in save_traceback
  File "/anaconda3/lib/python3.7/tempfile.py", line 340, in mkstemp
  File "/anaconda3/lib/python3.7/tempfile.py", line 258, in _mkstemp_inner
OSError: [Errno 24] Too many open files: '/var/folders/v3/8cncpb5d6wq_lmm7rg479mhc0000gq/T/sphinx-err-qng1i2ob.log'
Exception ignored in: <function BaseEventLoop.__del__ at 0x1063f48c8>
Traceback (most recent call last):
  File "/anaconda3/lib/python3.7/asyncio/base_events.py", line 625, in __del__
  File "/anaconda3/lib/python3.7/asyncio/unix_events.py", line 55, in close
  File "/anaconda3/lib/python3.7/asyncio/selector_events.py", line 86, in close
  File "/anaconda3/lib/python3.7/asyncio/selector_events.py", line 93, in _close_self_pipe
AttributeError: '_UnixSelectorEventLoop' object has no attribute '_ssock'

Expected behavior

Same successful building I’d had up until this point.

I’m very confused about why this began, because:

1. I can verify with git that none of my book’s source files has changed since the last successful build.
2. I uninstalled jupyter-book and reinstalled this morning, trying to test if #783 had been fixed, but then this happened.
3. I ran pip uninstall jupyter-book and pip install jupyer-book==0.7.3 to see if reverting could fix it, but alas, no.
4. I tried pip uninstall for jupyter-book, sphinx-book-theme, myst-nb, myst-parser, and jupyter-cache, then reinstall jupyter-book and still the same problem.

Environment

• Python Version 3.7.3
• Package versions or output of jupyter-book --version:

Jupyter Book: 0.7.4 (problem also occurs with 0.7.3, as mentioned above)
MyST-NB: 0.8.1
Sphinx Book Theme: 0.0.35
MyST-Parser: 0.8.1
Jupyter-Cache: 0.2.1

• Operating System: OS X 10.14.6

[nathancarter]

Wow, fast reply, thanks! I did pip install -I nbclient==0.2.0 and got a successful build again. Awesome!

[chrisjsewell]

no worries