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Update locket._LockFile implementation to avoid leaving open files #6122

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zanieb wants to merge 3 commits into from
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Update locket._LockFile implementation to avoid leaving open files #6122

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69138a4
Update `locket._LockFile` implementation to avoid leaving open files
zanieb Apr 13, 2022
aa72d74
Fix indent of release
zanieb Apr 13, 2022
a37b87e
Add check for missing file on release
zanieb Apr 13, 2022
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30 changes: 15 additions & 15 deletions distributed/locket.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,9 @@

from __future__ import annotations

import os
import threading
import warnings
import weakref
from time import sleep

Expand Down Expand Up @@ -154,26 +156,24 @@ def release(self):
class _LockFile:
def __init__(self, path):
self._path = path
self._file = None
self._thread_lock = threading.Lock()

def acquire(self, timeout=None, retry_period=None):
if self._file is None:
self._file = open(self._path, "wb")
if timeout is None and _lock_file_blocking_available:
_lock_file_blocking(self._file)
else:
_acquire_non_blocking(
acquire=lambda: _lock_file_non_blocking(self._file),
timeout=timeout,
retry_period=retry_period,
path=self._path,
)
with open(self._path, "wb") as fd:
if timeout is None and _lock_file_blocking_available:
_lock_file_blocking(fd)
else:
_acquire_non_blocking(
acquire=lambda: _lock_file_non_blocking(fd),
timeout=timeout,
retry_period=retry_period,
path=self._path,
)

def release(self):
_unlock_file(self._file)
self._file.close()
self._file = None
if os.path.exists(self._path):
with open(self._path, "wb") as fd:
_unlock_file(fd)
Comment on lines +174 to +176

@zanieb zanieb Apr 13, 2022 •
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This seems less than ideal, but if someone has already purged the worker directory this lock file is gone and we'll throw an exception here without checking if the path exists.

I originally included a warning but it is reraised as an error during Dask's test run and we'd have to ignore it or avoid calling release after the work space has been deleted.

Suggested change
if os.path.exists(self._path):
with open(self._path, "wb") as fd:
_unlock_file(fd)
if os.path.exists(self._path):
with open(self._path, "wb") as fd:
_unlock_file(fd)
else:
warnings.warn(f"Lock at {self._path!r} no longer exists and cannot be released.", stacklevel=2)



class _Locker:
Expand Down