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Last active December 8, 2022 08:05
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Simple python file locking context manager example on linux using python stdlib's `fcntl.flock`
import logging
import fcntl
from contextlib import contextmanager
def locked_open(filename, mode='r'):
"""locked_open(filename, mode='r') -> <open file object>
Context manager that on entry opens the path `filename`, using `mode`
(default: `r`), and applies an advisory write lock on the file which
is released when leaving the context. Yields the open file object for
use within the context.
Note: advisory locking implies that all calls to open the file using
this same api will block for both read and write until the lock is
acquired. Locking this way will not prevent the file from access using
any other api/method.
with open(filename, mode) as fd:
fcntl.flock(fd, fcntl.LOCK_EX)
logging.debug('acquired lock on %s', filename)
yield fd
# raw_input('press enter to release lock ')
logging.debug('releasing lock on %s', filename)
fcntl.flock(fd, fcntl.LOCK_UN)
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Typos: contexlib/contexmanager => contextlib/contextmanager

Nice gist!

cheers, thanks for reporting that !

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