prwlock 0.1.0

Native process-shared rwlock support for Python

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.

Usage

There is no need for initialization. Therefore, a code block such as the one below is enough to get an RWLock instance.

from prwlock.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.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])