Native process-shared rwlock support for Python
Project Description
A reader-writer lock for Python that can (must, actually) be used for locking across multiple Python processes.
The rationale and initial implementation of the project can be found in the accompanying blog post.
Installation
This package is available on PyPi, so you can install the latest stable
release with a simple pip
call:
$ pip install prwlock
Usage
All you have to do is import the module and start using it. There is no need for initialization. Therefore, a code block such as the one below is enough to get an RWLock instance.
from prwlock import RWLock rwlock = RWLock()
The RWLock itself is pickleable and, therefore, can be passed around to child processes, such as in the code block below.
from __future__ import print_function import os import time from multiprocessing import Pool from prwlock import RWLock def f(rwlock): for i in range(2): print(os.getpid(), 'Acquiring read lock') rwlock.acquire_read() print(os.getpid(), 'Sleeping for a while') time.sleep(1) print(os.getpid(), 'Releasing lock') rwlock.release() time.sleep(.1) r = RWLock() children = 20 pool = Pool(processes=children) for child in range(children): pool.apply_async(f, [r])
Context Managers
prwlock
also supports context managers using the with
syntax. The code
block below displays one possible way of using it.
from prwlock import RWLock # First you instantiate the lock rwlock = RWLock() # Now you can lock it in read or in write mode with rwlock.reader_lock(): # If this executes, then reader lock access has been acquired print('Reading data') # Likewise, you can lock in writer mode with: with rwlock.writer_lock(): print('Writing data')
Contributors
Changes
- 0.4.0: Added context-management support using the
with
syntax; - 0.3.0: Completed the API’s implementation. Namely:
- Added support for immediate failure when locks cannot be obtained;
- Added timeouts for obtaining the locks.
- 0.2.0: Added support for RWLocks on Windows XP and above. Changed the API so
that the lock can be imported as
from prwlock import RWLock
, instead of the slightly awkwardfrom prwlock.prwlock import RWLock
method. - 0.1.1: Fixed the value of the
PTHREAD_PROCESS_SHARED
constant for Mac OS X. Also added a check to prevent double destruction of the underlying lock on Mac OS X. - 0.1.0: Initial release
Download files
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Filename, size & hash SHA256 hash help | File type | Python version | Upload date |
---|---|---|---|
prwlock-0.4.0-py2-none-any.whl (15.5 kB) Copy SHA256 hash SHA256 | Wheel | py2 | Oct 18, 2016 |
prwlock-0.4.0-py3-none-any.whl (15.5 kB) Copy SHA256 hash SHA256 | Wheel | py3 | Oct 18, 2016 |
prwlock-0.4.0.tar.gz (10.4 kB) Copy SHA256 hash SHA256 | Source | None | Oct 18, 2016 |