aioprocessing 2.0.1

Description:

aioprocessing 2.0.1

aioprocessing

aioprocessing provides asynchronous, asyncio compatible, coroutine
versions of many blocking instance methods on objects in the multiprocessing
library. To use dill for universal pickling, install using pip install aioprocessing[dill]. Here's an example demonstrating the aioprocessing versions of
Event, Queue, and Lock:
import time
import asyncio
import aioprocessing


def func(queue, event, lock, items):
""" Demo worker function.

This worker function runs in its own process, and uses
normal blocking calls to aioprocessing objects, exactly
the way you would use oridinary multiprocessing objects.

"""
with lock:
event.set()
for item in items:
time.sleep(3)
queue.put(item+5)
queue.close()


async def example(queue, event, lock):
l = [1,2,3,4,5]
p = aioprocessing.AioProcess(target=func, args=(queue, event, lock, l))
p.start()
while True:
result = await queue.coro_get()
if result is None:
break
print("Got result {}".format(result))
await p.coro_join()

async def example2(queue, event, lock):
await event.coro_wait()
async with lock:
await queue.coro_put(78)
await queue.coro_put(None) # Shut down the worker

if __name__ == "__main__":
loop = asyncio.get_event_loop()
queue = aioprocessing.AioQueue()
lock = aioprocessing.AioLock()
event = aioprocessing.AioEvent()
tasks = [
asyncio.ensure_future(example(queue, event, lock)),
asyncio.ensure_future(example2(queue, event, lock)),
]
loop.run_until_complete(asyncio.wait(tasks))
loop.close()

The aioprocessing objects can be used just like their multiprocessing
equivalents - as they are in func above - but they can also be
seamlessly used inside of asyncio coroutines, without ever blocking
the event loop.
What's new
v2.0.1

Fixed a bug that kept the AioBarrier and AioEvent proxies returned from AioManager instances from working. Thanks to Giorgos Apostolopoulos for the fix.

v2.0.0

Add support for universal pickling using dill, installable with pip install aioprocessing[dill]. The library will now attempt to import multiprocess, falling back to stdlib multiprocessing. Force stdlib behaviour by setting a non-empty environment variable AIOPROCESSING_DILL_DISABLED=1. This can be used to avoid errors when attempting to combine aioprocessing[dill] with stdlib multiprocessing based objects like concurrent.futures.ProcessPoolExecutor.

How does it work?
In most cases, this library makes blocking calls to multiprocessing methods
asynchronous by executing the call in a ThreadPoolExecutor, using
asyncio.run_in_executor().
It does not re-implement multiprocessing using asynchronous I/O. This means
there is extra overhead added when you use aioprocessing objects instead of
multiprocessing objects, because each one is generally introducing a
ThreadPoolExecutor containing at least one threading.Thread. It also means
that all the normal risks you get when you mix threads with fork apply here, too
(See http://bugs.python.org/issue6721 for more info).
The one exception to this is aioprocessing.AioPool, which makes use of the
existing callback and error_callback keyword arguments in the various
Pool.*_async methods to run them as asyncio coroutines. Note that
multiprocessing.Pool is actually using threads internally, so the thread/fork
mixing caveat still applies.
Each multiprocessing class is replaced by an equivalent aioprocessing class,
distinguished by the Aio prefix. So, Pool becomes AioPool, etc. All methods
that could block on I/O also have a coroutine version that can be used with asyncio. For example, multiprocessing.Lock.acquire() can be replaced with aioprocessing.AioLock.coro_acquire(). You can pass an asyncio EventLoop object to any coro_* method using the loop keyword argument. For example, lock.coro_acquire(loop=my_loop).
Note that you can also use the aioprocessing synchronization primitives as replacements
for their equivalent threading primitives, in single-process, multi-threaded programs
that use asyncio.
What parts of multiprocessing are supported?
Most of them! All methods that could do blocking I/O in the following objects
have equivalent versions in aioprocessing that extend the multiprocessing
versions by adding coroutine versions of all the blocking methods.

Pool
Process
Pipe
Lock
RLock
Semaphore
BoundedSemaphore
Event
Condition
Barrier
connection.Connection
connection.Listener
connection.Client
Queue
JoinableQueue
SimpleQueue
All managers.SyncManager Proxy versions of the items above (SyncManager.Queue, SyncManager.Lock(), etc.).

What versions of Python are compatible?
aioprocessing will work out of the box on Python 3.5+.
Gotchas
Keep in mind that, while the API exposes coroutines for interacting with
multiprocessing APIs, internally they are almost always being delegated
to a ThreadPoolExecutor, this means the caveats that apply with using
ThreadPoolExecutor with asyncio apply: namely, you won't be able to
cancel any of the coroutines, because the work being done in the worker
thread can't be interrupted.