A thread-safe disk based persistent queue in Python.
Project description
This project is based on the achievements of python-pqueue and queuelib
The goals is to achieve following requirements:
Disk-based: each queued item should be stored in disk in case of any crash.
Thread-safe: can be used by multi-threaded producers and multi-threaded consumers.
Recoverable: Items can be read after process restart.
Green-compatible: It can be used in greenlet or eventlet environment.
While queuelib and python-pqueue cannot fulfil all of above. After some try, I found it’s hard to achieve based on their current implementation without huge code change. this is the motivation to start this project.
persist-queue use pickle object serialization module to support object instances. To support customized objects, please refer to Pickling and unpickling extension types(Python2) and Pickling Class Instances(Python3)
Requirements
Python 2.7 or Python 3.x.
Full support for Linux.
Windows support (with Caution).
Installation
from pypi
pip install persist-queuefrom source code
git clone https://github.com/peter-wangxu/persist-queue
cd persist-queue
python setup.py installExamples
>>> from persistqueue import Queue
>>> q = Queue("mypath")
>>> q.put('a')
>>> q.put('b')
>>> q.put('c')
>>> q.get()
'a'
>>> q.task_done()Close the python console, and then we restart the queue from the same path,
>>> from persistqueue import Queue
>>> q = Queue('mypath')
>>> q.get()
'b'
>>> q.task_done()example usage with multi-thread(referred from github project python-pqueue):
from persistqueue import Queue
q = Queue()
def worker():
while True:
item = q.get()
do_work(item)
q.task_done()
for i in range(num_worker_threads):
t = Thread(target=worker)
t.daemon = True
t.start()
for item in source():
q.put(item)
q.join() # block until all tasks are doneTests
persist-queue use tox to trigger tests.
to trigger tests based on python2.7/python3.x, use:
tox -e py27tox -e py34tox -e py35tox -e py36to trigger pep8 check, use:
tox -e pep8pyenv is usually a helpful tool to manage multiple versions of Python.
Caution
Currently, the atomic operation is not supported on Windows due to the limitation of Python’s os.rename, That’s saying, the data in queue could be in unreadable state when an incidential failure occurs during Queue.task_done. DO NOT PUT ANY CRITICAL DATA ON QUEUE WHEN RUNNING ON WINDOWS.
Contribution
Simply fork this repo and send PR for your code change(also tests to cover your change), remember to give a title and description of your PR. I am willing to enhance this project with you :).
License
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