Ggtcf

I have the following code:

def handle_empty_directories(dir):
 if os.path.exists(dir):
 shouter.shout("%s exists" % dir)
 else:
 shouter.shout("%s doesn't exists" % dir)
 entries = os.listdir(dir)
 if entries == []:
 open(os.path.join(dir, Commiter.hed_file), "w").close()
 else:
 if (len(entries) > 1) and (Commiter.hed_file in entries):
 os.remove(os.path.join(dir, Commiter.hed_file))
 for entry in entries:
 if entry not in Commiter.hed_ignore:
 full_entry = os.path.join(dir, entry)
 if (os.path.isdir(full_entry)):
 Commiter.handle_empty_directories(full_entry)

Occasionally, the call to os.listdir(dir) fails with FileNotFoundError even though the os.path.exists(dir) call says it exists:

08:57:56 - C:r2g-wdsport-6.0.5SBSSBSLightbincomibmArtifactTechnologyABSArtifactBroker exists
Traceback (most recent call last):
 File "migration.py", line 169, in <module>
 migrate()
 File "migration.py", line 80, in migrate
 rtc.acceptchangesintoworkspace(rtc.getchangeentriestoaccept(changeentries, history))
 File "c:UsersGeoffAlexanderDocumentsNirvanaRTC2Gitgit-repositoriesrtc2git-migration-toolrtcFunctions.py", line 304, in acceptchangesintoworkspace
 Commiter.handle_empty_directories(os.getcwd())
 File "c:UsersGeoffAlexanderDocumentsNirvanaRTC2Gitgit-repositoriesrtc2git-migration-toolgitFunctions.py", line 126, in handle_empty_directories
 Commiter.handle_empty_directories(full_entry)
 File "c:UsersGeoffAlexanderDocumentsNirvanaRTC2Gitgit-repositoriesrtc2git-migration-toolgitFunctions.py", line 126, in handle_empty_directories
 Commiter.handle_empty_directories(full_entry)
 File "c:UsersGeoffAlexanderDocumentsNirvanaRTC2Gitgit-repositoriesrtc2git-migration-toolgitFunctions.py", line 126, in handle_empty_directories
 Commiter.handle_empty_directories(full_entry)
 [Previous line repeated 6 more times]
 File "c:UsersGeoffAlexanderDocumentsNirvanaRTC2Gitgit-repositoriesrtc2git-migration-toolgitFunctions.py", line 116, in handle_empty_directories
 entries = os.listdir(dir)
FileNotFoundError: [WinError 3] The system cannot find the path specified: 'C:\r2g-wd\sport-6.0.5\SBS\SBS\Light\bin\com\ibm\ArtifactTechnology\ABS\ArtifactBroker'

How can this happen? I'm running Python 3.7.2 64-bit on Windows 10.

This is most likely a race condition. There is a period of time between testing if a directory exists, and then doing something to it, in which it can be deleted by another process.

The usual way to avoid this is to just try the action, and be ready for it to fail, e.g.:

try:
 os.listdir(x)
except FileNotFoundError:
 # log and stop here