From ae2fc277991f1717463f80aa98c57fd1f7718a87 Mon Sep 17 00:00:00 2001
From: Ronny Pfannschmidt <ronny.pfannschmidt@redhat.com>
Date: Wed, 24 Oct 2018 07:45:53 +0200
Subject: [PATCH] handle test folder cleanup being unable to create a cleanup
 lock

---
 changelog/4181.bugfix.rst |  1 +
 src/_pytest/pathlib.py    | 14 ++++++++++----
 testing/test_tmpdir.py    |  9 ++++++++-
 3 files changed, 19 insertions(+), 5 deletions(-)
 create mode 100644 changelog/4181.bugfix.rst

diff --git a/changelog/4181.bugfix.rst b/changelog/4181.bugfix.rst
new file mode 100644
index 000000000..668f8ba1e
--- /dev/null
+++ b/changelog/4181.bugfix.rst
@@ -0,0 +1 @@
+Handle race condition between creation and deletion of temporary folders.
diff --git a/src/_pytest/pathlib.py b/src/_pytest/pathlib.py
index 081fce904..85db5d674 100644
--- a/src/_pytest/pathlib.py
+++ b/src/_pytest/pathlib.py
@@ -182,9 +182,15 @@ def register_cleanup_lock_removal(lock_path, register=atexit.register):
     return register(cleanup_on_exit)
 
 
-def delete_a_numbered_dir(path):
-    """removes a numbered directory"""
-    create_cleanup_lock(path)
+def maybe_delete_a_numbered_dir(path):
+    """removes a numbered directory if its lock can be obtained"""
+    try:
+        create_cleanup_lock(path)
+    except (OSError, EnvironmentError):
+        #  known races:
+        #  * other process did a cleanup at the same time
+        #  * deletable folder was found
+        return
     parent = path.parent
 
     garbage = parent.joinpath("garbage-{}".format(uuid.uuid4()))
@@ -214,7 +220,7 @@ def ensure_deletable(path, consider_lock_dead_if_created_before):
 def try_cleanup(path, consider_lock_dead_if_created_before):
     """tries to cleanup a folder if we can ensure its deletable"""
     if ensure_deletable(path, consider_lock_dead_if_created_before):
-        delete_a_numbered_dir(path)
+        maybe_delete_a_numbered_dir(path)
 
 
 def cleanup_candidates(root, prefix, keep):
diff --git a/testing/test_tmpdir.py b/testing/test_tmpdir.py
index 3c413e7c2..c033c2143 100644
--- a/testing/test_tmpdir.py
+++ b/testing/test_tmpdir.py
@@ -4,6 +4,7 @@ import sys
 import six
 
 import pytest
+from _pytest import pathlib
 from _pytest.pathlib import Path
 
 
@@ -284,11 +285,17 @@ class TestNumberedDir(object):
         rmtree(adir, force=True)
         assert not adir.exists()
 
-    def test_cleanup_symlink(self, tmp_path):
+    def test_cleanup_ignores_symlink(self, tmp_path):
         the_symlink = tmp_path / (self.PREFIX + "current")
         attempt_symlink_to(the_symlink, tmp_path / (self.PREFIX + "5"))
         self._do_cleanup(tmp_path)
 
+    def test_removal_accepts_lock(self, tmp_path):
+        folder = pathlib.make_numbered_dir(root=tmp_path, prefix=self.PREFIX)
+        pathlib.create_cleanup_lock(folder)
+        pathlib.maybe_delete_a_numbered_dir(folder)
+        assert folder.is_dir()
+
 
 def attempt_symlink_to(path, to_path):
     """Try to make a symlink from "path" to "to_path", skipping in case this platform