OSError('[Errno 24] Too many open files') with pytest 3.3.0

After upgrading to pytest 3.3.0 (previously on 3.2.5), my unitests using pytest and GitPython are failing with:

Cmd('git') not found due to: OSError('[Errno 24] Too many open files')

More precisely, all of my tests pass up to a certain number (I don’t have the exact number right now), and then all the following tests start failing due to that error.

Unfortunately, I cannot share the code and tests (private projects).

Here’s a partial pip list, after removing a set of private packages:

amqp (1.4.9)
anyjson (0.3.3)
APScheduler (3.2.0)
asn1crypto (0.23.0)
attrs (17.3.0)
backports.shutil-get-terminal-size (1.0.0)
beautifulsoup4 (4.6.0)
billiard (3.3.0.23)
celery (3.1.18)
celery-with-redis (3.0)
certifi (2017.11.5)
cffi (1.11.2)
chardet (3.0.4)
check-manifest (0.36)
CherryPy (3.8.2)
click (6.7)
colander (1.0)
colorama (0.3.9)
cornice (1.0.0)
coverage (4.4.2)
cryptography (2.1.3)
decorator (4.1.2)
devpi-client (2.3.0)
devpi-common (3.2.0)
enum34 (1.0.4)
fastavro (0.14.11)
funcsigs (1.0.2)
functools32 (3.2.3.post2)
future (0.14.3)
futures (3.0.5)
gitdb2 (2.0.3)
GitPython (2.1.7)
graphviz (0.8.1)
hiredis (0.2.0)
idna (2.6)
ipaddress (1.0.18)
ipdb (0.10.3)
ipython (5.5.0)
ipython-genutils (0.2.0)
iso8601 (0.1.12)
Jinja2 (2.10)
jsonschema (2.6.0)
kafka-python (0.9.5)
kazoo (2.2.1)
kombu (3.0.37)
lxml (3.4.4)
MarkupSafe (1.0)
MiniMock (1.2.8)
mock (1.0.1)
msgpack-python (0.4.6)
MySQL-python (1.2.5)
nose (1.3.7)
nose-parameterized (0.3.5)
objgraph (3.1.2)
PasteDeploy (1.5.2)
pathlib2 (2.3.0)
pbr (1.10.0)
pickleshare (0.7.4)
pip (9.0.1)
pkginfo (1.4.1)
pluggy (0.6.0)
plumbum (1.6.4)
prompt-toolkit (1.0.15)
psutil (3.1.1)
py (1.5.2)
pycparser (2.18)
pycrypto (2.6.1)
pycurl (7.19.5.1)
PyDispatcher (2.0.5)
Pygments (2.2.0)
pymongo (3.5.1)
pyOpenSSL (17.4.0)
pypiwin32 (219)
pyramid (1.5.8)
pyreadline (2.0)
pytest (3.3.0)
pytest-mock (1.6.3)
python-dateutil (2.4.2)
python-memcached (1.57)
python-memcached-stats (0.1)
pytz (2017.3)
PyYAML (3.11)
pyzmq (14.7.0)
redis (2.10.6)
repoze.lru (0.6)
requests (2.18.4)
scandir (1.6)
setuptools (28.8.0)
setuptools-scm (1.15.6)
simplegeneric (0.8.1)
simplejson (3.8.2)
six (1.11.0)
smmap2 (2.0.3)
SQLAlchemy (1.0.8)
sqlalchemy-migrate (0.11.0)
sqlparse (0.2.4)
statsd (3.2.1)
stevedore (1.20.1)
tabulate (0.7.7)
Tempita (0.5.2)
tox (2.9.1)
traitlets (4.3.2)
translationstring (1.3)
tzlocal (1.4)
urllib3 (1.22)
validators (0.10.1)
venusian (1.1.0)
virtualenv (15.1.0)
waitress (1.1.0)
wcwidth (0.1.7)
web.py (0.37)
WebOb (1.7.4)
WebTest (2.0.29)
wheel (0.29.0)
win-unicode-console (0.5)
wincertstore (0.2)
wrapt (1.10.11)
xmltodict (0.11.0)
zope.deprecation (4.3.0)
zope.interface (4.4.3)

What I can tell is that those tests perform a lot of “git clone” operation into temp directories made using the tmpdir and tmpdir_factory fixtures. The only peculiar thing I can think of about my use case is that I have some fixtures from the “per test” level using “session” level fixtures.

Here’s an almost identical copy of the conftest.py:

import os

import git
import pytest

@pytest.fixture(scope="session")
def remote_repo(tmpdir_factory):
    tmpdir = tmpdir_factory.mktemp('repos')
    tmpdir.chdir()
    os.mkdir('remote')

    # Repo init (on master by default)
    repo = git.Repo.init('remote')
    # I simplified/obfuscated a part of the git operation here.
    # lots of repo operation like making commits, creating branch and making tag...
    repo.index.commit('master 1st commit')
    repo.index.commit('master 2nd commit')
    master = repo.heads.master

    master.checkout()
    releases_1_0 = repo.create_head('releases/1.0')
    releases_1_0.checkout()
    repo.index.commit('releases 1.0 1st commit')
    repo.index.commit('releases 1.0 2nd commit')
    repo.create_tag('v1.0.0', message='v1.0.0')

    master.checkout()
    merge_base = repo.merge_base(master, releases_1_0)
    repo.index.merge_tree(releases_1_0, base=merge_base)
    repo.index.commit('1st Merge releases/1.0 into master',
                      parent_commits=(master.commit, releases_1_0.commit))

    master.checkout()
    repo.index.commit('master 3rd commit')
    repo.index.commit('master 4th commit')

    return repo


@pytest.fixture(scope="session")
def _local_repo(remote_repo):
    return remote_repo.clone(os.path.abspath('./local'))


@pytest.fixture()
def local_repo_per_session(_local_repo):
    os.chdir(_local_repo.working_dir)
    return _local_repo


@pytest.fixture()
def local_repo_per_test(tmpdir, remote_repo):
    clone = remote_repo.clone(str(tmpdir.join('./local')))
    os.chdir(clone.working_dir)
    return clone

And then I have tests using local_repo_per_session or local_repo_per_test depending on if the test is only doing reads, or if it will change the repo given by the fixture.

It feels as if the file handler for per-test level fixtures aren’t closed properly anymore, but that’s only my guess.

You can ask for more details about the tests, I’ll try to give as much information as I can / am allowed to.

Pytest version: 3.3.0 Python: 2.7 (32 bits version) OS: Windows 7/10

• Include a detailed description of the bug or suggestion
• pip list of the virtual environment you are using
• pytest and operating system versions
• Minimal example if possible

[tonybaloney]

Thank you for this well documented issue, I stumbled across the same thing 👍 @nicoddemus

[vphilippon]

Thanks for the quick reply, I’ll check this tomorrow morning (EST)