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Description:

fasteners 0.19

Fasteners

Cross-platform locks for threads and processes.
🔩 Install
pip install fasteners

🔩 Usage
Lock for processes has the same API as the
threading.Lock
for threads:
import fasteners
import threading

lock = threading.Lock() # for threads
lock = fasteners.InterProcessLock('path/to/lock.file') # for processes

with lock:
... # exclusive access

# or alternatively

lock.acquire()
... # exclusive access
lock.release()

Reader Writer lock has a similar API, which is the same for threads or processes:
import fasteners

rw_lock = fasteners.ReaderWriterLock() # for threads
rw_lock = fasteners.InterProcessReaderWriterLock('path/to/lock.file') # for processes

with rw_lock.write_lock():
... # write access

with rw_lock.read_lock():
... # read access

# or alternatively

rw_lock.acquire_read_lock()
... # read access
rw_lock.release_read_lock()

rw_lock.acquire_write_lock()
... # write access
rw_lock.release_write_lock()

🔩 Overview
Python standard library provides a lock for threads (both a reentrant one, and a
non-reentrant one, see below). Fasteners extends this, and provides a lock for
processes, as well as Reader Writer locks for both threads and processes.
Definitions of terms used in this overview can be found in the
glossary.
The specifics of the locks are as follows:
Process locks
The fasteners.InterProcessLock uses fcntl on Unix-like systems and
msvc _locking on Windows.
As a result, if used cross-platform it guarantees an intersection of their features:

lock
reentrant
mandatory

fcntl
✘
✘

_locking
✔
✔

fasteners.InterProcessLock
✘
✘

The fasteners.InterProcessReaderWriterLock also uses fcntl on Unix-like systems and
LockFileEx on Windows. Their
features are as follows:

lock
reentrant
mandatory
upgradable
preference

fcntl
✘
✘
✔
reader

LockFileEx
✔
✔
✘
reader

fasteners.InterProcessReaderWriterLock
✘
✘
✘
reader

Thread locks
Fasteners does not provide a simple thread lock, but for the sake of comparison note that the threading module
provides both a reentrant and non-reentrant locks:

lock
reentrant
mandatory

threading.Lock
✘
✘

threading.RLock
✔
✘

The fasteners.ReaderWriterLock at the moment is as follows:

lock
reentrant
mandatory
upgradable
preference

fasteners.ReaderWriterLock
✔
✘
✘
writer

If your threads are created by some other means than the standard library threading
module (for example eventlet), you may need to provide the corresponding thread
identification and synchronisation functions to the ReaderWriterLock.